Patients undergoing complex spine surgery present with multilevel spinal involvement, advanced age, and multiple comorbidities. Surgery is associated with significant blood loss and remarkable hemodynamic changes. The present study aimed to investigate the accuracy and trending ability of a non-invasive continuous method to monitor hemoglobin (SpHb) concentrations using a Radical-7™ Pulse CO-Oximeter in complex spine surgery.Forty-nine patients who underwent complex spine surgery were enrolled in this prospective observational study. Multiple time points were established for data collection throughout the operation. Simultaneous SpHb–total hemoglobin (tHb) paired data were recorded for analyses. Linear regression analysis, Bland–Altman plot, four-quadrant plot, and Critchley polar plot were used to assess the accuracy and trending ability of the monitor.n = 200) and PI values < 1.0 (n = 72). The correction coefficients (r) between SpHb and tHb were 0.6946 and 0.6861 in the groups with PI values ≥1.0 and < 1.0, respectively (P < 0000.1). In the ≥1.0 group, the mean bias was − 0.21 g/dL and the percentage error (PE) was 15.85%, whereas in the < 1.0 group, the mean bias was − 0.04 g/dL and the PE was 17.42%. Four-quadrant plot revealed a concordance rate of 85.11%, whereas the Critchley polar plot showed a concordance rate of 67.21%.A total of 272 pairs of SpHb-tHb data were available and were divided into two groups based on the perfusion index (PI): PI values ≥1.0 (The present study demonstrates the acceptable accuracy of the Radical-7™ Pulse CO-Oximeter even with a low PI. However, the trending ability was limited and unsatisfactory. Total hemoglobin (tHb) concentration continues to be the reference or threshold for administering packed red blood cells in clinical practice . In someThe Masimo Radical-7™ Pulse CO-Oximeter  is a commercially available device to monitor hemoglobin concentration, providing a real-time, continuous, non-invasive measurement during various major surgeries and in critical populations under intensive care. Using multi-wavelength spectrophotometric detection, this device analyzes the different optical densities passing through the tissue. In interpretation of the digital signal, the immediate and continuous hemoglobin (SpHb) concentration may become one of the parts of monitors and offer the physicians a reference point in decision-making.Complex spine surgery procedures have increasingly been performed over the past few decades , 7, withThis study was approved by the Institutional Review Board of Chang Gung Medical Foundation in Taiwan (registration number: 201701229B0). Informed consent was obtained from all the voluntary participants after the details of the study were explained by the study investigators. Overall, 50 patients scheduled to undergo spine surgery at the Chang Gung Memorial Hospital in Taiwan, between August 2017 and January 2018, were enrolled in this prospective study. Patients who were aged < 20 years; those who exhibited an inability to use the upper extremities for monitoring; those who were diagnosed with preoperative arrhythmia, peripheral vascular diseases, hematologic diseases; and those who refused to provide consent were excluded. The criteria for complex or complicated spine surgery were as follows: the involvement of ≥3 levels of the lumbar spine segment; estimated blood loss of > 500 mL or a prediction of blood transfusion; and an estimated period of ≥4 h for the complete procedure. Most patients underwent posterior spinal fusion with the instrumentation of implants. Indications for the surgical procedure included spinal stenosis, debridement, scoliosis correction, and instrumentation revision.2, 30–40 mmHg; and end expiratory pressure, 5 cmH2O. Following the induction of anesthesia and tracheal intubation, a 20-gauge catheter was implanted into the radial artery as an arterial line to monitor the perioperative blood pressure and to withdraw the blood sample for measurement of hemoglobin concentration. The adhesive sensor  was wrapped onto the index finger of the patient and connected to the Radical-7™ Pulse CO-Oximeter to continuously monitor the SpHb value. After the completion of arterial line implantation, the blood pressure cuff was removed. To eliminate optical interference, the sensor was set to the hand without the arterial line, intravenous line, and pulse oximeter. The sensor was covered with opaque tape for protection from the ambient streams of light. The blood sample was analyzed in the operation room within 5 min after withdrawn from the radial arterial line. A blood gas analyzer  was adopted in the operation room of our institution. The analyzer calibration was routinely performed according to the manufacturer’s instructions.On arrival at the operation room, all patients were regularly monitored using a thermometer, electrocardiograph, pulse oximetry, and non-invasive blood pressure cuff. General anesthesia was performed in all patients using a standardized protocol. The induction anesthetics included propofol (1.5–2 mg/kg), fentanyl (1–2 mcg/kg), and cisatracurium (0.2 mg/kg) to facilitate tracheal intubation . The mechanical ventilator was adjusted as follows: tidal volume, 6–8 mL/kg; respirator rate, 8–16 breaths per min; end-tidal COSeveral time points were established for data collection. The SpHb values were recorded for every blood sample (tHb) obtained, and the paired data were recorded during the following time points: immediately after the induction of anesthesia; at the start of the surgical procedure; every 1 hour thereafter; at the end of the operation or when the patient had arrived at the post-anesthesia room; and before leaving the post-anesthesia room. The anesthesiologists were blinded to the recorded data, and the study investigators were not involved in anesthesia management during the operation. The anesthesiologists were responsible for the perioperative fluid supplement and blood transfusion as well as for controlling the stability of the vital signs. The SpHb values from the Radical-7™ Pulse CO-Oximeter monitor did not influence the decision-making during the whole procedure.Descriptive data including the basic patient demographic data, total surgery/anesthesia time and the number of spine levels involved were recorded. In addition, the amount of intravenous fluids, including crystalloids and blood products, were recorded.The demographic and clinical data were summarized as descriptive statistics. Patient characteristics are expressed as mean value ± standard deviation (SD). For analysis of the correlations between paired SpHb and tHb values, the linear regression analysis was applied. To assess the accuracy of SpHb, Bland–Altman analysis was performed, and the results were reported as the mean bias ±1.96 SD. The mean bias was calculated as the average difference between SpHb–tHb pairs. Limits of agreement (LoA) were calculated as the mean bias ±1.96 SD. The percentage error in this study was calculated with the LoA divided by the mean hemoglobin data {100 × [LOA/ (mean SpHb + mean tHb)/2]}. Although several studies have excluded data with low perfusion values , 23, 24,Trending ability was assessed in addition to the accuracy analysis. We used the four-quadrant plot and Critchley polar plot methods to test the magnitude and directionality of the change in hemoglobin concentration. The central exclusion zones were set as 1.0 (g/dL) in both statistical methods to minimize the interference of analysis. Following the exclusion of the data in the central zones, the concordance rate was defined as the proportion of the total number of the points in the same direction of changes in tHb and SpHb to the total number of points on the four-quadrant plot. In the Critchley polar plot, the concordance rate was defined as the percentage of points within the ±30° radial zone to the total number of points on the polar plot.P value of < 0.05 was considered significant for all analyses.Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 22.0  and R 3.2.0 statistical software . A n = 49) was 65.53 ± 11.87 years. Based on the American Society of Anesthesiologists (ASA) classification, most cases were class 3 (85.7%), whereas the remaining were class 2 (14.3%). Estimated blood loss was 766.33 ± 564.71 mL (ranging from 100 to 2600 mL) and intravenous crystalloid supplement was 1474.49 ± 510.63 mL (450 to 3650 mL). The amount of blood products transfused during the surgery was as follows: packed red blood cells, 2.94 ± 2.35 units; and fresh frozen plasma, 2.33 ± 2.29 units. Mean surgical duration was 217.8 ± 68.4 min and the mean total anesthesia time was 264.43 ± 66.6 min. The number of spinal levels involved ranged from 3 to 13.Of the 50 patients initially enrolled in the study, one was excluded due to failure of the arterial line during the surgery, resulting in a total of 49 patients who were included in the final analysis. Patient demographic characteristics and perioperative data are shown in Table n = 200) and PI values < 1.0 (n = 72). The hemoglobin concentrations ranged from 8.9 to 16.8 g/dL (SpHb) and 9.3 to 16.6 g/dL (tHb). Linear regression analysis indicated correlations between SpHb and tHb values with a correction coefficient (r) of 0.6946 in the ≥1.0 group .Overall, 272 pairs of SpHb–tHb data were obtained and were divided into two groups based on the perfusion index (PI): PI values ≥1.0 . The central exclusion zone was applied at ±1.0 g/dL to rule out the pairs of data with minimal consecutive difference in both plots. The concordance rate was 85.11% in the four-quadrant plot Fig.  and 67.2The accurate and rapid measurement of hemoglobin concentration is crucial during the decision-making process for fluid and transfusion therapy in complicated surgical procedures. Several articles have discussed the accuracy of Radical-7™ Pulse CO-Oximeter –18; howeIn the present study, we investigated patients undergoing complex spine surgery and presenting with the characteristic features of multilevel spinal involvement, prolonged operation time, significant blood loss, and remarkable hemodynamic changes. In addition, the intervention of fluid supplements, transfusion of blood products, and the use of vasopressors to perioperatively maintain the hemodynamic stability are common in these patients. Moreover, patients receiving complex spine surgery are mostly older in age, and may suffer from multiple comorbidities; therefore, the risks involved with anesthesia and surgery are increased in these patients. Our patient demographic data are compatible with this population, revealing a mean age of 65.53 ± 11.87 years with 85.7% of the participants belonging to the ASA class 3 category.The values of perfusion index (PI) indicate the quality of recorded SpHb on the Radical-7™ Pulse CO-Oximeter monitor. Miller et al.  have repThe results of the current study may not be satisfactory in terms of testing the trending ability. According to the study by Critchley et al., a concordance rate of > 92% is considered as good and acceptable for evaluation of the trending ability , 26. In Prone position is acquired in the posterior approach spine surgery to assess the dorsal side of the body. Increased intra-abdominal pressure in prone position contributes to subsequent physiological changes such as decreased cardiac index, inferior vena caval obstruction, and pulmonary ventilation/perfusion distribution . It is rIn the present prospective observational study, we did not analyze the effect of Radical-7™ Pulse CO-Oximeter on transfusion therapy. From our perspective, we consider that the ability of this monitor to reduce over- and under-transfusion during surgery. Awada et al. have reported that fewer blood products were transfused and a shorter duration of delayed transfusion was observed in SpHb-guided group . AnotherSeveral factors influence the peripheral blood perfusion such as use of vasopressors, body temperature, and severe anemia. The present study has some limitations. First, we did not encounter cases with significant hypothermia (body temperature < 35 °C) or severe anemia (Hb < 7 g/dL) or that of patients using vasopressors; so we were unable to test the accuracy of SpHb in such groups. Besides, although the SpHb sensor was covered to avoid optical interference, environment light pollution may be of concern in the accuracy of results. Furthermore, we did not compare the cost efficiency of the SpHb monitor with standard laboratory analysis, which may be of importance in several institutions worldwide. A larger sample size including diverse patient populations is recommended. Although we had divided the PI values into two groups for statistical analyses, the relation between PI and the monitor accuracy remains interesting and several levels of PI in different groups may be considered for analysis. As mentioned above, several factors can pose a challenge and further studies investigating these factors are required in future.The traditional central laboratory analysis is time consuming and may not be available in some institutions, although the incorporation of point-of-care satellite laboratory stations in operating rooms has gained popularity. In addition, it is potentially risky for clinicians who may be injured or infected during withdrawal of blood samples every day. The Masimo Radical-7™ Pulse CO-Oximeter is a non-invasive, immediate, and consecutive method that perioperatively provides the hemoglobin concentrations of the patients. The use of non-invasive monitoring techniques is popular in clinical practice in the current era; nevertheless, this study does not advocate it as a replacement of the traditional methods of measurement. On the contrary, laboratory analyses continue to remain as the gold standard for the accumulation of accurate data. It is rational to check the laboratory values at critical time points when significant intraoperative events occur  or when remarkable variations in the monitor data are noted . The use of the monitoring device in conjunction with laboratory analysis may prove helpful in clinical practice.In conclusion, the present study demonstrates the acceptable accuracy of the Masimo Radical-7™ Pulse CO-Oximeter in measuring the hemoglobin concentration even under low perfusion index levels. Although the trending ability of this monitor is limited and unsatisfactory, it may be used as a reference for making decisions with regard to transfusion therapy for complex spine surgery.


Lung-protective ventilation and prolonged prone positioning (PP) are presented as essential in treating acute respiratory distress syndrome (ARDS). The optimal respirator mode, however, remains controversial. Pressure-supported spontaneous breathing (PS) during ARDS provides several advantages, but is difficult to achieve during PP because of respiratory depression as a side effect of sedative drugs. This study was designed to evaluate the feasibility and safety of PS during PP in ARDS patients sedated with inhaled sevoflurane.Overall, we have observed 4339 h of prone positioning in 62 patients who had a median of four prone episodes during treatment. Within 3948 h (91%), patients were successfully brought into a pressure-supported spontaneous breathing mode. The median duration of each prone episode was 17 h (IQR 3). Median duration of pressure-supported spontaneous breathing per episode was 16 h (IQR 5). Just one self-extubation occurred during 276 episodes of PP.Pressure-supported spontaneous breathing during prolonged prone positioning in intubated ARDS patients with or without ECMO can be achieved during volatile sedation with sevoflurane. This finding may provide a basis upon which to question the latest dogma in ARDS treatment. Our concept must be further investigated and compared to controlled ventilation with regard to driving pressure, lung-protective parameters, muscle weakness and mortality before it can be routinely applied. Adherence to a bundle of respirator settings termed “lung-protective ventilation” , 2 and pcontrolled ventilatory mode during PP under deep intravenous sedation [supported spontaneous breathing has not been systemically evaluated so far due to the dilemma between sedation necessary to tolerate PP and sedative-induced depression of respiratory genesis [In recent trials, patients were mechanically ventilated in a sedation , 4, 22.  genesis , 23, 24. genesis . It also genesis . Inhaled genesis .We hypothesized that pressure-supported spontaneous breathing during PP would be feasible during volatile sedation with sevoflurane. In this retrospective observational trial, we evaluated a cohort of patients with moderate or severe ARDS. The primary endpoint was length of PS in hours related to the PP duration. Secondary outcome parameter was the incidence of sedation-related unexpected events.2O) were treated according to a standardized departmental protocol  or those who only revealed side positioning or incomplete PP (130°) were also excluded from analysis.® Infinity® V500 respirator, it is mandatory to continuously measure the inspiratory and expiratory sevoflurane concentration. With this setting, inhalative sedation has proven to be safe for ICU sedation and is covered by national guidelines [Sedation was established via inhaled sevoflurane  applied continuously with the AnaConDa™ System . Target xMAC  was 0.4–0.6, resulting in an endtidal concentration between 0.5 and 1.3 Vol % depending on sex and age. Exhaled sevoflurane was measured with a “Vamos” monitor system . Volatiles are not yet licensed to sedate ICU patients; therefore, this indication is off-label use. When connecting an AnaConDa™ to Dräger Evitaidelines .Sedation target during PP was a calm patient without pronounced or potentially harmful body movement concordant with preserved sufficient spontaneous breathing (pH > 7.2). Limited by the difficulty to accurately assess the Richmond Agitation and Sedation Scale (RASS)  in PP, tPatients also received basic analgesia with opioids, mainly gastric-retarded morphine or oxycodone. Especially during the start of the study period, patients received continuously infused sufentanil instead. Intravenous piritramid, a low-potent opioid, was additionally applied as nurse-controlled analgesia (NCA). As the visual analogue scale (VAS) cannot be applied in pronely positioned sedated patients, criteria for opioid application were symptoms of stress or pain like tachypnea, tachycardia, sweating, body motion, etc.2) was set aiming for an arterial oxygen partial pressure (paO2) of ≥ 60 mmHg. Patients were converted to the pressure-supported spontaneous breathing (PS) mode “SPN-CPAP/PS” (spontaneous-continuous positive airway pressure/pressure support) at the Evita® Infinity® V500 respirator . Criteria for reconverting to PCV were respiratory acidosis with blood pH < 7.2. Respirator settings were switched to the pressure-controlled ventilation (PCV) mode “PC-BIPAP” (pressure control biphasic positive airway pressure); opioid application was reduced and when patients started breathing spontaneously, the respirator again was switched to SPN-CPAP/PS mode. If spontaneous breathing could not be established promptly and accumulated opioids were the most likely reason, naloxone was administered in 0.04 mg steps in line with the responsible nurse’s discretion. Basic opioid therapy was then reduced. Nurses were advised to aim for tidal volumes of ≤ 8 ml/kg predicted body weight [Positive end expiratory pressure was set at between 12 and 16 mbar. Inspiratory fraction of oxygen . Reports on the patients’ condition were documented every 8th hour by both nurses and intensivists in the electronic chart. Every shift report was screened with special regard to unexpected events, especially harmful body motion, self-extubation or hemodynamic instability for this analysis.®  to calculate the median and inter quartile range (IQR).Data were collected in Microsoft Excel sheets . Statistical analysis was performed with GraphPad InStatFor details on patient selection, please see Fig. Cohort characteristics are listed in Table Three patients in PP already presented RASS values of − 5; thus, prescribed sevoflurane was not applied in line with the responsible nurse’s discretion. Two patients with only “mild” ARDS had been intubated before for other reasons and were brought to PP because respiratory function would probably worsen in due course.).Overall, 4339 h of prone positioning have been observed. Within 3948 h (91%), patients were switched successfully to a pressure-supported spontaneous breathing mode . Median duration of pressure-supported spontaneous breathing per episode was 16 h (IQR 5). Results are listed in Table As presented in Fig. Unexpected events related to prone positioning or inhaled sedation are listed in Table Three circulatory arrests have been observed in temporary but not clearly in causal connection with prone positioning and sevoflurane-sedation:One patient (number 051) suffered from septic shock with abdominal focus. Because of multiorgan failure und underlying morbidities, this patient had been considered ECMO-unsuitable. He was turned to prone positioning as ultima ratio because of severe hypoxia. Despite mildly improved oxygenation, he died of uncontrolled lactic acidosis.One patient (number 097) connected to venovenous ECMO developed severe septic shock and acute renal failure following pneumonia. Due to metabolic acidosis and increased serum potassium, he presented with ventricular tachycardia and severe hypotension and was successfully resuscitated after turning to supine position but died from septic shock in the following hours.One patient (number 101) developed right heart failure. He was turned back and resuscitation was started. After returning to spontaneous circulation continuously infused epinephrine and inhaled nitric oxide were started. Unfortunately, the patient died the next day.This observational feasibility trial is the first to systemically evaluate inhaled sedation with sevoflurane for PP in combination with PS. Conversion to PS succeeded in 91% of the cumulative hours of PP. During 276 episodes with over 4000 h of PP, no related fatal event occurred. With a median RASS value of − 4.5, a sufficient sedation depth was achieved in 59 (95%) out of 62 patients with a combination of sevoflurane and opioids.The finding that PS during PP in intubated ARDS patients is safely achievable during volatile sedation with sevoflurane forms the basis from which to question the current dogma in ARDS treatment. On the other hand, this approach inherits the risk of hyperinflation due to increased respiratory effort. This concept must therefore be investigated in comparison with controlled ventilation in terms of driving pressure, lung-protective parameters, muscle weakness and mortality before it can be routinely applied.There is still no convincing evidence for what constitutes the optimal respirator mode to achieve lung-protective parameters and to decrease driving pressure in ARDS . In the Crotti et al.  found thThere are various possible advantages of PS during ARDS: Muscle activation may help prevent diaphragm atrophy  and actiThe main concern associated with spontaneous breathing during ARDS is the increase in transpulmonary pressure with consecutive spatial hyperinflation. This effect seems to mainly threaten the ventral areas of the lung during supine position. Stabilizing the chest wall’s anterior through the patient’s bodyweight in PP alleviates this theoretical harm during PS , 18, 49.2, paCO2, pH, inflammation, body temperature, agitation, etc.) described elsewhere [1), we chose arbitrary thresholds of > 60 mmHg for paO2 and pH > 7.2, respectively, to establish FiO2 and pressure support. The analgosedation regimen based mainly on varying the endtidal sevoflurane concentration and opioid application does not specifically address all the aforementioned parameters. During over 90% of cumulative hours of PS during PP, however, it really worked in clinical practice even in patients with blood pH values below 7.2.The genesis of respiration and the respiratory drive are controlled by complex feedback loops and dependent on various parameters . One of them (No 67) was put into PP because pulmonary function was rapidly worsening and severe ARDS developed in due course. The other patient (No 78) was extubated after the first PP episode, and treatment was continued with noninvasive ventilation. Ten patients had been diagnosed with severe ARDS in primary hospitals and were then connected to ECMO by our outreach team and referred to our ICU. The 47% mortality in our cohort is therefore comparable or even lower than expected when compared to epidemiological data [Mortality was not an endpoint of this study. Most of the patients at ICU admission had severe (55%) or moderate (42%) ARDS. Two intubated patients were admitted to ICU with “mild” ARDS Table . One of cal data .This “proof-of-principle” trial’s main drawback is its retrospective design. A control group would have been desirable. The use of inhaled anesthetics requires deep understanding of malignant hyperthermia, and dantrolene must be at hand. While absorbers and gas exhaustion systems keep the ambient air load minimal, the global warming potential of sevoflurane is enormous . The AnaPressure-supported spontaneous breathing in patients undergoing prone positioning in ARDS is feasible and safe during inhaled sedation with sevoflurane—a concept that challenges current state-of-the-art ARDS therapy. Research should now focus on comparing controlled and pressure-supported spontaneous ventilator settings during PP and the effects on driving pressure, lung-protective parameters, muscle weakness and mortality in a larger cohort. These investigations are essential before the PS approach during PP can be routinely recommended.


Autonomic control of blood pressure (BP) and heart rate (HR) is crucial during bleeding and hemorrhagic shock (HS) to compensate for hypotension and hypoxia. Previous works have observed that at the point of hemodynamic decompensation a marked suppression of BP and HR variability occurs, leading to irreversible shock. We hypothesized that recovery of the autonomic control may be decisive for effective resuscitation, along with restoration of mean BP. We computed cardiovascular indexes of baroreflex sensitivity and BP and HR variability by analyzing hemodynamic recordings collected from five pigs during a protocol of severe hemorrhage and resuscitation; three pigs were sham-treated controls. Moreover, we assessed the effects of severe hemorrhage on heart functionality by integrating the hemodynamic findings with measures of plasma high-sensitivity cardiac troponin T and metabolite concentrations in left ventricular (LV) tissue. Resuscitation was performed with fluids and norepinephrine and then by reinfusion of shed blood. After first resuscitation, mean BP reached the target value, but cardiovascular indexes were not fully restored, hinting at a partial recovery of the autonomic mechanisms. Moreover, cardiac troponins were still elevated, suggesting a persistent myocardial sufferance. After blood reinfusion all the indexes returned to baseline. In the harvested heart, LV metabolic profile confirmed the acute stress condition sensed by the cardiomyocytes. Variability indexes and baroreflex trends can be valuable tools to evaluate the severity of HS, and they may represent a more useful end point for resuscitation in combination with standard measures such as mean values and biological measures.NEW & NOTEWORTHY Autonomic control of blood pressure was highly impaired during hemorrhagic shock, and it was not completely recovered after resuscitation despite global restoration of mean pressures. Moreover, a persistent myocardial sufferance emerged from measured cardiac troponin T and metabolite concentrations of left ventricular tissue. We highlight the importance of combining global mean values and biological markers with measures of variability and autonomic control for a better characterization of the effectiveness of the resuscitation strategy. Hemorrhage and unresolved hemorrhagic shock (HS) still represent the leading cause of mortality after trauma in both civilian and military settings, with the majority of deaths occurring because of the inability to control bleeding and to effectively resuscitate hemorrhage patients , 67.Therefore, much effort has been spent on investigation of the fundamental underlying pathophysiology of HS in order to develop innovative approaches or to discover new biological parameters capable of detecting the severity of blood loss, controlling bleeding, and guiding resuscitation.HS is a form of hypovolemic shock in which an acute reduction in central blood volume causes organ hypoperfusion and consequently an inadequate oxygen supply at the cellular level. Clinical signs of this condition are severe hypotension and hypoxia, pronounced tachycardia and tachypnea, diffused coagulopathy, hypothermia, and metabolic acidosis .During progressive hemorrhage, physiological compensatory mechanisms are usually elicited in trying to maintain homeostasis. Indeed, the cardiovascular system activates physiological responses with the aim of maintaining cerebral oxygenation and blood supply to central organs; for example, neuroendocrine-mediated modifications of peripheral vascular resistance cause a redistribution of fluids that leads to nonuniform regional blood loss. Other compensatory mechanisms consist of an increase in heart rate (HR) and myocardial contractility to increase cardiac output (CO) .The role of the sympathetic autonomic nervous system (ANS) has been demonstrated to be crucial during bleeding to prevent collapse through reflex tachycardia and peripheral vasoconstriction , 24, 60.Standards of resuscitation for prehospital hemorrhagic trauma patients include administration of fluids to stabilize BP and vascular volume before blood transfusion and surgical repair. However, after the replacement of blood loss the consequent restoration of CO and ABP does not accurately reflect the effectiveness of treatment , 58. In For this reason, resuscitation science has tried to identify other surrogates able to assess cardiocirculatory status and tissue perfusion so as to better depict shock severity and response to treatment  , 59.In this study, we analyzed the cardiovascular signals recorded during a protocol of severe hemorrhage and resuscitation with the aim of characterizing the compensatory response to hypovolemia and fluid repletion in terms of autonomic-mediated changes in BP variability and HR variability (HRV).Furthermore, hemorrhage is known to induce a sort of myocardial injury , and theFor these reasons, we assessed the effects of severe hemorrhage on heart functionality and cardiac tissue by integrating the hemodynamic findings with measurements of plasma high-sensitivity cardiac troponin T (hs-cTnT) and metabolite concentrations in left ventricular (LV) tissue.−1·h−1), midazolam (2–4 mg·kg−1·h−1), and sufentanil (0.3 μg·kg−1·h−1). Animals were mechanically ventilated with a tidal volume of 10 ml/kg−1 and inspired O2 fraction of 0.21 during baseline and 0.3 during and after the shock phase; respiratory frequency was adjusted to maintain the end-tidal partial pressure of CO2 (Pco2) values in the range 35–40 mmHg. A 7-Fr catheter was placed in the descending aorta from the left femoral artery for blood sample collection. Another Millar Mikro-Tip pressure catheter was inserted in the right femoral artery for continuous monitoring of ABP. Continuous acquisition of central venous pressure in the right atrium, pulmonary arterial pressure, and CO through thermodilution technique was obtained by means of an endovascular pentalumen 7-Fr catheter placed in the pulmonary artery from the right femoral vein. Continuous monitoring of LV pressure and volume was achieved by means of a Millar Mikro-Tip pressure catheter inserted in the LV cavity from the right carotid artery. Finally, a 14-Fr catheter was placed in the abdominal artery from the left femoral artery for blood withdrawal during the induction of shock, and a 14-Fr catheter was inserted in the left femoral vein for the successive blood reinfusion. The study was reviewed and approved by the Institutional Review Board and the governmental institution .Nine male pigs (36 ± 2 kg) received anesthesia by intramuscular injection of ketamine (20 mg/kg), completed by ear vein injection of propofol (2 mg/kg) and sufentanil (0.3 μg/kg) and then maintained over the whole experiment with continuous intravenous administration of propofol (1–3 mg·kg1) HS and resuscitation (n = 6) and 2) sham-treated control (n = 3). Bleeding was induced by withdrawal of blood from the left femoral artery with a peristaltic pump at a rate of 20 ml/min over an interval of 60 min, until mean arterial pressure (MAP) reached values of 40 ± 5 mmHg. The hypoxic state with the consequent metabolic alteration was confirmed by serial blood lactate measurements. After 2 h of the shock condition, animals were resuscitated with a two-step procedure. Initially, fluid  and vasopressor (norepinephrine) were administered to restore MAP of at least 60 mmHg and a pulse pressure variation < 12%. Then, shed blood was reinfused with the aid of a peristaltic pump over an interval of 30 min. After 1 h of observation, animals were euthanized by intravenous injection of Tanax (1 ml/10 kg) and heart biopsies from the LV were taken for histological, biochemical, and omics analyses.After baseline measurements, animals were randomized to one of two study groups: For sham-treated animals the preparation was identical, but they did not undergo bleeding, fluid resuscitation, or blood reinfusion. One of six HS animals was excluded because of elevated blood pressure at baseline (MAP of 130 mmHg).Animals were studied at four relevant time points: at baseline (T1), after the development of HS (T2), after fluid and vasopressor resuscitation (T3), and after blood reinfusion (T4).At each time point a bolus of phenylephrine (3 μg/kg) and a bolus of epinephrine (10 μg) were intravenously administered to elicit the response of the ANS. Arterial and venous blood samples were collected for blood gas analysis and laboratory analyses . Plasma hs-cTnT was measured in a central laboratory by electrochemiluminescence immunoassay using commercial reagents .After death, a thoracotomy was immediately performed, the heart was exposed, and the LV anterior free wall opposite to septum 1 cm below mitral valve level was removed and collected. Samples of 50–60 mg comprising the entire thickness of the muscle (endocardium to epicardium) were rinsed with protease inhibitor solution and stored at −80°C.co2 in arterial blood (mmHg), partial pressure of O2 in arterial blood , base excess (mEq/l), hs-cTnT (ng/ml), oxygen saturation (%), hematocrit (%), and LV ejection fraction .Clinical variables collected at each time point were the following: CO (l/min), temperature (°C), urine output (ml), arterial pH, lactate (mmol/l), Ptmax) was derived on a beat-to-beat basis from the LVP recording, and it was taken as an indirect measure of heart contractility. Temporal relationships were maintained among the time series: given R(i) as the R peak of the current beat, RRI(i) designated the difference between R(i + 1) and R(i), SAP(i) follows R(i) and is followed by DAP(i), dP/dt(i) is the slope of the upstroke right after R(i), and RAP(i) is the averaged RAP values within RRI(i). Finally, an adaptive filter was applied to the data to remove outliers and irregularities , LV pressure (LVP), and right atrial pressure (RAP) were continuously recorded during the experiment. At each time point stationary segments of 7-min length on average were selected. R-R intervals (RRI) and HR time series were extracted from the ECG waveform by means of the ECG Analysis Module available for LabChart software; time series of systolic (SAP), diastolic (DAP) and mean (MAP) arterial pressure were obtained from the ABP waveform with specific algorithms , 74. Bealarities . Each seAll the indexes obtained for these series were averaged and considered for successive statistical comparisons.tmax, and RAP series.We computed the mean value of SAP, DAP, MAP, RRI, dP/dSpectral indexes obtained from power spectra included low-frequency  power distribution, total power (TP), which represents the total area under the spectrum and is a measure of the overall variability of the series, and LF%, which represents the relative power in the LF band and is computed as LF/(TP − VLF)%, where VLF is the very low-frequency component (0–0.04 Hz).i) cannot immediately affect SAP(i), a one-beat delay was considered for the FF relationship. Granger causality from SAP to RRI and vice versa was verified before computation of the gains , the standard deviation of successive differences between adjacent RRI (SDSD), and the standard deviation of the overall RRI time series (SD) . MoreoveTo better investigate the different mechanisms of peripheral resistance control, we implemented a multi-input single-output causal black-box model for the prediction and spectral decomposition of DAP beat-to-beat fluctuations from variability signals of SAP, RAP, and RRI. The methodological principles underlying multivariate linear black-box modeling have been exhaustively illustrated elsewhere . Assuminhrr(1), for physiological reasons. Granger causality among the cardiovascular time series was verified before computation of the model  represents the black-box model for the arterial baroreflex mediated sympathetic control of vasomotor tone.SAP → DAP (DAP •rap) represents the black-box model of vasomotor tone control related to the cardiopulmonary baroreflex; we assumed that RAP oscillations are representative of pressure oscillations sensed by cardiopulmonary baroreceptors.RAP → DAP (DAP •rr) represents the mechanical effect of diastolic runoff.RRI → DAP (DAPnoise) includes all the remaining sources of variability not measured, such as the influence of DAP past values, the autoregulation-mediated control of peripheral resistance, possible errors, or noise.The residual error  and then assessed the ratio of LF power of DAPsap, DAPrap, or DAPrr components over total LF power DAP , respectively.To quantify the amount of DAP variability explained by each component, a spectral decomposition was performed. In particular, we performed spectral analysis of the model component series  tandem mass spectrometry (MS/MS) assay  was applied to metabolomics analysis. The assay quantifies 188 metabolites from five analyte groups: acylcarnitines, amino acids, biogenic amines, hexoses (sum of hexoses), phosphatidylcholines, and sphingomyelins. The method combines derivatization and extraction of analytes with the selective MS detection using multiple reaction monitoring pairs. Samples were analyzed with an LC/MS  method  followed by flow injection analysis-MS . Methodological details and data preprocessing have been extensively reported in our previous articles  separately at each time point, whereas we used the Friedman test to assess significant changes among time points within the same group of animals. Significance was considered at P < 0.05.We adopted the Mann-Whitney tmax) and lactate compared with sham-treated animals  suggested that the severity of shock was not sufficient to induce a concurrent acute heart failure.tmax, even if less marked. Baroreflex FB gain was reduced at T2 and T3 (significantly at T2) and recovered at T4; the opposite trend was observed for FF gain.tmax during bolus injection. Both MAP and HR variations in response to phenylephrine and dP/dtmax variation in response to epinephrine were greatly reduced with respect to baseline at the end of the shock period  was predominant with respect to the other mechanisms in each phase of the experiment  and the portion of DAP variability regulated by the cardiopulmonary baroreflex (LF DAPrap/LF DAP) presented a u-shaped trend: they decreased during the shock period, remained lower than baseline after resuscitation, and recovered to baseline values after blood reinfusion.As regards the DAP model, the portion of DAP variability mediated by the arterial baroreflex mechanism . Only 11 metabolites significantly changed concentrations between sham-treated and HS pigs in LV tissue . LV tissThe trends of vital signs and lactate confirmed the hypovolemic shock associated with a hyperdynamic cardiovascular response , Table 1Changes in LF oscillations of BP can be related to changes in the outflow of the sympathetic nervous system, and spectral analysis of BP has been proven to be a powerful tool for identification of the different cardiovascular control mechanisms that regulate BP , 66. FroMany hypotheses have been formulated in the past years, trying to explain this phenomenon. Some literature supports the concept that an “empty heart” might contribute to cardiac receptor stimulation, resulting in the activation of cardiac vagal afferents and subsequent sympathetic depression , 62, 64.The available data and the results of our study do not fully support one of the above mechanisms. However, the hypothesis of prolonged brain ischemia-mediated sympathetic depression can be excluded since the shock condition was not prolonged for long and all animals recovered after blood reinfusion. Interestingly, after resuscitation with fluid and vasopressor (T3) the level of LF power did not recover to baseline value despite the animals reaching the target MAP values, and CO was higher than baseline . TherefoAs regards the cardiac baroreflex sensitivity (BRS) we observed a significant decrease of sensitivity during shock (BRS FB gain) that persisted even after the resuscitation maneuvers at T3 . A dynamInterestingly, the opposite trend was observed for the feedforward gain (BRS FF gain), or runoff effect, which was higher compared with baseline both in shock (T2) and after fluid and vasopressor resuscitation (T3). This may be due to a markedly high HR.sap) significantly increased with respect to baseline, passing from ~30% to 80% in all animals. The other components  decreased at T2 and T3 with respect to baseline  LVEF returned to baseline value, but only after blood reinfusion (T4) did both CO and dP/dThese results suggest that the shock insult did not impair cardiac contractility. The main reason for this result could be the short period of shock before initiation of treatments. Indeed, in our study shock was maintained up to 2 h after confirmation of lactate increase, while in previous experimental studies of HS the onset of myocardial depression was usually observed between 2 and 5 h after insult , 55. In Nevertheless, plasma hs-cTnT increased significantly in shocked animals, remained high after fluid resuscitation, and finally returned to baseline values after blood reinfusion. The severity and the kinetics of troponin release do not support the hypothesis of an acute coronary syndrome , 31; indAnother possible explanation of the increase in hs-cTnT could be the mechanical stress on the LV wall in the condition of elevated myocardial contractility and low filling volume, which causes sarcomere disruption in a highly susceptible spot  . UnfortuAs regards metabolomics findings, only a small subset of the measured metabolites were differently abundant in LV tissue between HS and sham treatment . A distuConcomitantly, raised plasmalogen levels such as PCasC38:0 and PCec42:3, which act as endogenous antioxidants , may proTogether these findings converge toward a plausible adaptation of the LV metabolic asset to cope with the insult. Such change in the metabolic asset might also be viewed as a key mechanism for either membrane structural rearrangement or damage to cardiomyocytes  and migh−), an oxidizing agent associated with cell damage, decreased myocardial contractility, and congestive heart failure  formation. In heart, alterations of the arginine-NO pathway have been reported in chronic heart failure . NO synt failure .The main limitation of this study is the small sample size. Moreover, the short time between T2 (shock), T3 (resuscitation), and T4 (blood reinfusion) could have attenuated the effects of shock in the physiological and metabolic responses. Finally, the unavailability of direct measures of autonomic outflow, such as muscle or cardiac sympathetic nerve activity, did not permit more than speculation about the compensatory mechanisms that are activated or suppressed during shock and resuscitation.The results of this study suggest that BP variability, HRV, and baroreflex trends can be valuable tools to evaluate the severity of HS and they may represent a more useful end point for resuscitation, in combination with standard measurements such as mean values and biological measurements. In fact, they can add important insights into the recovery of the autonomic mechanisms of BP and HR regulation, which are fundamental for the recovery of organ dysfunction in shocked subjects. In this study, for example, resuscitation with fluid and vasopressor was effective in restoring circulating volume, CO, and mean BP, but indexes of autonomic functionality revealed that ANS control was not fully recovered. Interestingly, the high concentrations of cardiac troponin and a dysregulated metabolism in the LV tissue after resuscitation are signs of a stress condition induced by shock not resolved by the resuscitation maneuver.This study was supported by the European Union FP7 Health Programme, ShockOmics Project, Grant No. 602706.No conflicts of interest, financial or otherwise, are declared by the authors.G. Baselli and M.F. conceived and designed research; G. Babini and G.R. performed experiments; M.C., R.P., L.B., and M.F. analyzed data; M.C., G. Babini, G.R., R.P., and M.F. interpreted results of experiments; M.C. prepared figures; M.C. drafted manuscript; M.C., G. Babini, G.R., R.P., and M.F. edited and revised manuscript; M.C., G. Babini, G. Baselli, G.R., R.P., L.B., and M.F. approved final version of manuscript.Supplemental TableSupplemental Table: Dataset of all measured metabolites concentration - .xlsx (237 KB)


During a mean follow-up period of 41.9 months, 87 developed end-stage kidney disease (ESKD). The incidence rates of ESKD were comparable between the patients treated and untreated with urate-lowering agents. The Kaplan-Meier analysis indicated that kidney survival was also comparable between them. In the multivariate analysis, heart failure and low eGFR were the significant prognostic factors for kidney survival. However, pharmacologic urate-lowering therapy was not predictive of kidney survival. The overall GFR decline rate was also comparable between the groups (P = 0.13). The efficacy of pharmacologic urate-lowering therapy in delaying CKD progression remains controversial. Therefore, further randomized controlled trials are needed to confirm its efficacy in attenuating kidney function deterioration in patients with stage 3–4 CKD.Because the serum uric acid level increases as the glomerular filtration rate (GFR) decreases, hyperuricemia is associated with chronic kidney disease (CKD). Although hyperuricemia is a risk factor for CKD progression, the causal role of uric acid remains controversial in patients with CKD and asymptomatic hyperuricemia. This study included 588 patients with stage 3–4 CKD and asymptomatic hyperuricemia. Using propensity score matching, 165 pairs treated and untreated with pharmacologic urate-lowering therapy were matched. Kaplan-Meier curves were constructed to determine the effect of urate-lowering agents on kidney survival. The prognostic value for kidney survival was ascertained using Cox regression analysis. The GFR changes over time between the patients treated and untreated with urate-lowering agents were assessed using a linear mixed model analysis. The mean age of the matched patients was 63.2 ± 12.7 years, and 52 (15.8%) patients had diabetic nephropathy. The mean estimated GFR (eGFR) and serum uric acid level were 36.7 mL/min/1.73 m Uric acid is the poorly soluble circulating end-product of purine metabolism in humans owing to the loss of uricase activity . It has Although hyperuricemia is strongly associated with the development of CKD, whether it plays a role in the deterioration of kidney function or is only a marker reflecting such deterioration remains controversial in patients with CKD. In this context, some epidemiologic studies showed no relationship between hyperuricemia and deterioration of kidney function , 13. On The objective of this long-term observational study is to explore the effect of pharmacologic urate-lowering therapy on the kidney function of patients with CKD and asymptomatic hyperuricemia via propensity score matching.This study was performed in accordance with the Declaration of Helsinki principles and approved by the Institutional Review Board (IRB) of Kangdong Sacred Heart Hospital (Ref. no. 2019-01-005). This was a retrospective medical record-based study, and the study subjects were de-identified. The IRB waived the need for written consent from the participants.2  age of ≥ 18 years; 2) estimated glomerular filtration rate (eGFR) of 15 to 60 mL/min/1.73 mequation ) for > 3The date of the first occurrence of a serum uric acid level of > 7 mg/dL was defined as the index date. The inclusion and exclusion criteria were applied on the basis of the index date. To evaluate the effect of long-term hyperuricemia on kidney function, the serum uric acid levels were also investigated during the follow-up period. To capture longitudinal changes in serum uric acid, the area under the serum uric acid level-time curve was calculated and adjusted on the basis of the total follow-up period . In otheAmong eligible patients followed-up in nephrology clinic at Kangdong Sacred Heart Hospital, the decision to treat with urate-lowering agents was made by nephrologists. Patients in treated group received urate-lowering agents from the index date. Urate-lowering agents were titrated or switched to other alternative drugs for reaching the target uric acid level (< 6 mg/dL).The initial study endpoint was the development of end-stage kidney disease (ESKD), defined as a condition needing maintenance dialysis or kidney transplantation. Meanwhile, the changes in the eGFR over time were evaluated according to whether the patients were treated with urate-lowering agents. In addition, subgroup analyses of eGFR decline slopes were conducted for sex, age, diabetes, CKD stage, heart failure, proteinuria, and serum uric acid level.http://cran.r-progect.org/). The Kolmogorov-Smirnov test was used to analyze the normality of parameter distribution for continuous variables. Continuous variables were expressed as means ± standard deviations or medians (interquartile ranges) and categorical variables as numbers (percentages). Propensity score matching was performed using the MatchIt package in R and variables collected at the index date. Patients with the nearest propensity scores in the two groups (patients treated and untreated with urate-lowering agents) were matched using a 1:1 scheme without replacement using a greedy algorithm. Greedy algorithm is a simple, intuitive algorithm that is used in optimization problems. The algorithm makes the optimal choice at each step as it attempts to find the overall optimal way to solve the entire problem. Propensity score matching allowed the comparison of outcomes between individuals with a similar likelihood. Differences between the two groups were assessed using the t-test, Wilcoxon’s rank sum test, and chi-squared test. Standardized mean differences were also estimated to evaluate the pre-match and post-match imbalance. Kidney survival curves were generated using the Kaplan-Meier method, and between-group survival was compared using the log-rank test. The prognostic values for kidney survival were analyzed by performing Cox regression analysis. The slope of the decline in kidney function over time was calculated using a linear regression analysis of the serial eGFR for each patient. The changes in the eGFR over time were compared between the two groups using a linear mixed model analysis. In this analysis, the patients treated and untreated with urate-lowering agents and follow-up period were treated as fixed effects, and each patient was treated as a random effect such that each subject had a unique intercept and slope. All probabilities were two-tailed, and the level of significance was set at 0.05.Statistical analyses were performed using the SPSS 19.0  and R version 3.5.1  patients.The baseline characteristics of the patients treated and untreated with urate-lowering agents are shown in Ninety patients were prescribed with allopurinol as the urate-lowering agent. The starting dose of allopurinol ranged from 50 mg/day to 100 mg/day, with 100 mg/day being the most common . The maintenance dose of allopurinol was 100 mg in 65 patients, 200 mg in 23 patients, and 300 mg in two patients. Thirty-four patients switched to febuxostat with a maintenance dose of 40 mg/day. The reason for discontinuation of allopurinol was inefficacy or presence of side effects. Meanwhile, 75 patients were prescribed with febuxostat. The starting dose of febuxostat ranged from 20 mg/day to 40 mg/day, with 20 mg/day being the most common . The maintenance dose of febuxostat was 40 mg in 71 patients and 80 mg in four patients.P < 0.001) and actual serum uric acid level  were significantly lower in the patients treated with urate-lowering agents than in those untreated with such. Among the patients treated with urate-lowering agents, the percentage of those whose serum uric acid levels decreased to 6.0 mg/dL during the first 3 months was 98.2%.The baseline serum uric acid levels were comparable between the patients treated and untreated with urate-lowering agents. However, the final serum uric acid level . The Kaplan-Meier analysis indicated that kidney survival was also comparable between them .The eGFR during the follow-up period is shown in The subgroup analysis of the eGFR decline slope was conducted according to sex, age, heart failure, diabetes, proteinuria, CKD stage, and serum uric acid level. It revealed no significant difference between the patients treated and untreated with urate-lowering agents .We evaluated the efficacy of urate-lowering agents in attenuating the deterioration of kidney function and effects on the associated clinical factors in patients with stage 3–4 CKD and asymptomatic hyperuricemia. Although clinical factors, such as diabetes, proteinuria, heart failure, and baseline eGFR, affect the deterioration of kidney function, there was no significant difference in kidney survival between the patients treated and untreated with urate-lowering agents. In addition, the subgroup analysis of the eGFR decline slope according to sex, age, heart failure, diabetes, proteinuria, CKD stage, and serum uric acid level revealed no significant difference between them.There is accumulating evidence that hyperuricemia has a causal relationship with the deterioration of kidney function –12; howeIt is well known that certain clinical factors, such as diabetes, proteinuria, heart failure, and baseline eGFR, could exacerbate the eGFR decline rate in patients with CKD –31. In oXanthine oxidase inhibitors with either allopurinol or febuxostat are recommended as the first-line pharmacologic urate-lowering agents . AllopurOur study has certain limitations. First, the study was an uncontrolled retrospective study. However, propensity score matching was used to reduce any bias owing to confounding variables commonly found in uncontrolled data. In addition, in most patients treated with urate-lowering agents, the uric acid levels were consistently maintained at < 6.0 mg/dL for a long period. Second, only a small number of patients were enrolled in this study. Therefore, the interpretation of the subgroup analysis findings may be limited. Third, different agents  were prescribed as the urate-lowering agents in our study.In conclusion, considering the side effects of urate-lowering agents in patients with CKD, there is a need to establish their efficacy according to certain pathologic conditions in patients with stage 2–3 CKD. Therefore, a large-scale prospective trial is needed to confirm such.S1 FigULT, urate-lowering therapy.(TIF)Click here for additional data file.


It has long been believed that kidney function is linked to brain activity. Clinical studies demonstrate that patients with chronic kidney disease (CKD) are more prone to cognitive impairment and Alzheimer’s disease (AD), and the degree of cognitive impairment is closely related to CKD progression and renal failure. Moreover, the fact that cognitive function in CKD patients is significantly improved after successful kidney transplantation reveals a linkage between CKD and AD. However, the mechanisms behind this linkage are unclear. The physiological function of the kidney is to maintain the stability of the internal environment, including the cerebrovascular circulation, whereas abnormal kidney function often leads to ischemia and hypoxia. Many CKD patients experience chronic hypoxia, and many urinary toxins accumulate after renal function is impaired. In this mini review, we will propose a novel perspective on the association between AD and CKD and the connection between the kidney and brain. In traditional medicine, it is believed that the kidney is the congenital foundation of the human body, and it produces and stores an “essence.” The kidney was believed to play an important role in governing water, the vascular system, the heart, growth and the brain in ancient China, as shown in Figure p < 0.001)  for at least 3 months  . CKD is 3 months . Patient3 months . The low3 months . Moreove3 months . Further3 months .The kidney is the organ with the highest blood flow in the human body, as calculated by the blood flow per gram of organ. The high blood flow rate of the kidney far exceeds the needs of its own metabolism. In a sense, we understand that the kidney is an organ composed of large numbers of blood vessels that help maintain the stability of its internal environment. The blood flow through the kidneys is very fast, approximately 1200 mL per minute in a resting, healthy, normal adult, which is approximately 20–25% of the total cardiac output; moreover, the blood running through the kidneys is filtered and reabsorbed to excrete metabolic waste from the body and maintain the stability of the internal environment  .The oxygen consumption of the human brain is approximately 1/5 that of the whole body, and the amount of blood reaching the human brain is approximately 15% of the total cardiac output. The cerebral cortex is very sensitive to ischemia and hypoxia of the cerebral blood circulation . Normal 1 or CKD2 have mild renal injury, patients with CKD3 or CKD4 have moderate to severe renal injury, and stage CKD5 is end-stage renal disease (ESRD) or renal failure, requiring dialysis. CKD promotes the progression of AD  . The accThe elevation of plasma Hcy (serum homocysteine) is a strong risk factor of AD and vascular disease . There iThe massive accumulation of urinary toxins can directly act on multiple organs in the body through blood flow. For example, there is a large accumulation of parathyroid hormone (PTH) in the blood when patients have renal dysfunction. PTH can pass through the blood-brain barrier, and one study found that the PTH2 receptor was widely distributed in the central nervous system . It has The urinary toxin aluminum can also pass through the blood-brain barrier and act on brain tissue. Aluminum is involved in metabolic processes and redox reactions in the central nervous system, and the level of aluminum in serum is a risk factor for AD . The accCognitive function abnormalities are characteristic of hemodialysis patients, and hemodialysis patients have more cerebral atrophy, partly caused by cerebral ischemia during dialysis . PatientThe risks of cognitive impairment in AD patients with CKD are significantly higher than those in patients without CKD , not onlThere are many common characteristics between the pathogenesis of AD and that of CKD, including vascular dysfunction or degeneration , aging , hyperteAt present, diagnosis of AD is mainly determined by physicians’ subjective experience and neuropsychological tests . UnfortuThe traditional pathological hallmarks in the AD brain are neuron/synapse loss and the presence of large numbers of senile plaques and neurofibrillary tangles in the cerebral cortex and hippocampus. Aβ protein is a major component of senile plaques and can be secreted directly into cerebrospinal fluid (CSF) by neurons .Interestingly, it was also found that serum Aβ levels were significantly higher in CKD patients , possibl5)  .Serum homocysteine (Hcy) is a sulfur-containing amino acid . As mentProteinuria and eGFR are common indicators for renal function . Protein2)], and the GFR is the amount of fluid produced by the two kidneys per unit of time. The GFR is currently calculated by the endogenous marker creatinine in the clinic. Creatinine is excreted by renal tubules and is not metabolized by the kidneys. In patients with CKD, excretion of creatinine by renal tubules is lower, the GFR is lower, and the serum concentration of creatinine is higher.Glomerular filtration function is expressed by the GFR, [mL/(min 1.73 mProteinuria and eGFR are closely related to cognitive decline . One stuErythropoietin (EPO) is mainly produced in the kidney ; EPO proA large cohort study with 3591 subjects found that CKD patients were more likely to exhibit cognitive decline. However, after adjusting for hemoglobin concentration, this link became weak or disappeared , suggestThe concentration of cystatin C is mainly determined by the GFR because the kidney is the only organ that cleanses cystatin C . ResearcThe levels of cystatin C in the plasma of AD patients were lower than those in the age-matched control group . It is uUremic toxins have been among the most studied factors leading to uremia since 1840 when P.A. Piorry and D.I. Heritier proposed the concept of uremia . It has summary, numerous epidemiological studies demonstrate that there is a high incidence of cognitive impairment or AD-like dementia in CKD patients of all ages. This discovery highlights a new direction for the diagnosis and potential treatment of both CKD and AD. Vascular injury and the direct neurotoxicity of uremic toxins caused by renal dysfunction are the most reasonable mechanisms of the effects of CKD in AD patients. We might obtain unexpected results if we focus our attention on changes occurring in both the brain and the kidneys in further studies in the prevention and treatment of CKD and AD.YaS and ZL contributed to drafting and revising this manuscript. YoS and HZ designed and revised this manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Methods: We measured forehead ΔtHb, ΔHbO2, and ΔdeoxyHb in response to HOB elevation (30°) within 72 h (first measurement) and 7–10 days (second measurement) after AIS onset using time-resolved near-infrared spectroscopy. Results: We enrolled 30 participants  with a first AIS. There were no significant differences in ΔtHb, ΔHbO2, or ΔdeoxyHb measurements on the infarct or contra-infarct side. At the first measurement, ΔtHb, ΔHbO2, and ΔdeoxyHb measured on the contra-infarct side did not correlate with those measured on the infarct side: ΔtHb ; ΔHbO2 ; ΔdeoxyHb . Notably, at the second measurement, correlation coefficients of ΔtHb and ΔHbO2 between the contra-infarct and infarct sides were statistically significant: ΔtHb ; ΔHbO2 ; ΔdeoxyHb . Conclusion: Although changes in cerebral oxygenation in response to HOB elevation had a laterality difference between hemispheres within 72 h of AIS onset, the difference had decreased, at least partially, 7–10 days after AIS onset.Background: Cerebral oxygenation monitoring provides important information for optimizing individualized management in patients with acute ischemic stroke (AIS). Although changes in cerebral oxygenation are known to occur in response to head-of-bed (HOB) elevation within 72 h after onset, changes in cerebral oxygenation during stroke recovery are unclear. We compared changes in total- (tHb), oxygenated- (HbO Acute ischemic stroke (AIS) is a significant cause of permanent disability . Early r2), and deoxygenated-hemoglobin (deoxyHb) concentrations in response to head-of-bed (HOB) elevation between the infarct and contra-infarct sides have never been assessed, leaving the changes in cerebral oxygenation during stroke recovery not well understood. In the current exploratory study, we therefore aim to compare the changes in tHb (ΔtHb), HbO2 (ΔHbO2), and deoxyHb (ΔdeoxyHb) in response to HOB manipulation between the timeframes within 72 h and 7–10 days after AIS onset.Near-infrared spectroscopy (NIRS) noninvasively measures hemoglobin (Hb) levels in the brain . CompareThis study was designed as a single-center exploratory study to compare the changes in cerebral oxygenation in response to HOB manipulation between different time points in AIS patients, and it was conducted at Seirei Mikatahara General Hospital, Hamamatsu, Japan. Study participants were consecutively recruited from among acute cerebral infarction patients hospitalized at our hospital from September 2016 to March 2017. Eligible patients were those having a first-ever ischemic stroke and who had been hospitalized within 24 h of symptoms onset. Main exclusion criteria were a patient with infratentorial stroke; a history of cerebral disease ; orthostatic hypotension; taking antihypertensive agents after hospitalization; or unable to participate in this study ; unable to follow verbal instructions).http://www.umin.ac.jp/ctr/index.htm. Unique identifier: UMIN 000022904).This study protocol complied with the Helsinki Declaration. The institutional research review board of Seirei Mikatahara General Hospital and Hamamatsu University School of Medicine approved the study (Approved number 16-15 and 16-001). Written informed consent was provided by all participants. The study was registered at the UMIN Clinical Trials Registry , because the farther the distance, the weaker the light reaching the reception probe. One study reporting simultaneous measurements with TRS-10 and PET found that TRS-10 measurements with irradiation and reception probes 3 cm apart significantly correlated with PET measurements around gray matter [We used a single-channel, time-resolved NIRS system  to measure bilateral forehead cerebral  hemoglobin concentration. The temporal profile obtained from TRS-10 measurement was fitted with that obtained from the theoretical solution of the photon diffusion equation (DE) , becausey matter . We ther2, and deoxyHb within 72 h (first measurement) and 7–10 days (second measurement) after AIS onset. After placing probes on the forehead, the participant laid on his/her back. Data were collected every 10 s for 5 min at each HOB angle  sequentially. At each HOB angle, the mean tHb, HbO2, and deoxyHb values were calculated after discarding data obtained during the first minute, because it took 15 s to change the HOB position of the bed. Because the TRS-10 system has a single channel, two consecutive measurements were conducted in each participant. We first measured forehead tHb, HbO2, and deoxyHb on the contra-infarct side and then on the infarct side. Systemic blood pressure and heart rate were also measured for 1 min in each position using an automatic hemodynamometer .Based on previous studies ,22,23,242, and deoxyHb were compared with the baseline (HOB 0°). These measurement values at HOB 30° were compared with those at HOB 0° using the Wilcoxon signed-rank test. Correlations between the infarct and contra-infarct sides for each measurement were assessed using Spearman’s rank correlation coefficient. The significance of the difference between the two correlation coefficients was evaluated using the Fisher r-to-z transformation. p < 0.05 was regarded as indicating statistical significance. All statistical analyses were performed using PASW Statistics version 18.0.0  and Microsoft Excel 2016 .Values are expressed as means ± standard deviations (SD) or medians (interquartile range)  of the indicated numbers or proportions (%). Changes in systemic blood pressure, heart rate, tHb, HbOAltogether, 32 AIS patients met the inclusion criteria and were enrolled. Two participants died before the second measurements and were excluded from the analyses. The participants’ characteristics are shown in p = 0.74), DBP (p = 0.87), heart rate (p = 0.94); second measurement: SBP (p = 0.83), DBP (p = 0.94), heart rate (p = 0.30).2 and deoxyHb , infarct side ; ΔHbO2: contra-infarct side , infarct side ). Although correlation coefficients in the contra-infarct side seemed to indicate a stronger relation than those in the infarct side, there were no statistically significant differences for ΔtHb or ΔHbO2 ; ΔHbO2 ), ΔdeoxyHb did not show a significant correlation between the first and second measurements ; infarct side ).2, and ΔdeoxyHb in response to HOB elevation between the infarct and contra-infarct sides. At the first measurement, ΔtHb, ΔHbO2, and ΔdeoxyHb measured on the contra-infarct side did not correlate with those on the infarct side , ΔHbO2 ; ΔdeoxyHb ) ; ΔHbO2 ; ΔdeoxyHb ) ( 0.221)) A–C. Nota 0.054)) D–F.2, and ΔdeoxyHb also did not change in response to HOB elevation, although large interindividual variabilities were observed. (2) ΔtHb and ΔHbO2 in response to HOB elevation measured within 72 h of AIS onset showed significant correlations with those measured 7–10 days after AIS onset in both hemispheres. (3) Although ΔtHb, ΔHbO2, and ΔdeoxyHb measured on the infarct side did not correlate with those measured on the contra-infarct side within 72 h of AIS onset, the correlation coefficients of these NIRS parameters were significantly correlated between the hemispheres 7–10 days after AIS onset. We believe that this is the first study to assess the effect of gradual HOB manipulation (from 0° to 30°) of forehead hemoglobin concentration in AIS patients, revealed by two measurements using NIRS. There were three main findings of this investigation. (1) The HOB elevation from 0° to 30° did not affect systemic blood pressure or heart rate. ΔtHb, ΔHbO2, and deoxyHb concentrations for either hemisphere over two measurements. However, as shown in 2, and deoxyHb showed large differences among individuals. Approximately half of our study patients showed increased cerebral hemoglobin concentrations  in response to HOB elevation for either hemisphere over the two measurements. This paradoxical response phenomenon was in line with previous reports that evaluated the effect of head-position changes on cerebral oxygenation in AIS patients [2, and ΔdeoxyHb concentrations did not change in response to HOB elevation.It is known that CBF velocity (CBFV) and the total cerebral Hb concentration are reduced in head-up position of healthy subjects and chronic ischemic stroke patients. Furthermore, decreases in CBVF and cerebral Hb concentration could be affected by a drop in systemic blood pressure ,25,26,27patients ,17. Sevepatients ,28,29,302, and ΔdeoxyHb concentrations in response to HOB elevation between the infarct and contra-infarct sides had not been reported prior to this study. Thus, we seem to be the first to show that the ΔtHb and ΔHbO2 measurements within 72 h of AIS onset significantly correlated with those 7–10 days after AIS onset for either hemisphere. Notably, although the ΔtHb, ΔHbO2, and ΔdeoxyHb, in response to HOB elevation, did not show a significant correlation between hemispheres within 72 h of AIS onset, correlations of the ΔtHb, ΔHbO2, and ΔdeoxyHb 7–10 days after onset were statistically significant. Although we could not clarify the mechanism of this alteration, various possible explanations are assumed. Changes in cerebral oxygenation variables in response to HOB manipulation reflected CBF volume change. It could be related with gravitational force acting on passively contacted brain vessels in the ischemic territory [2, and ΔdeoxyHb on the infarct side in response to HOB elevation could not be denied because we did not monitor the ICP in our participants. Development of collateral circulation also affected the changes in ΔtHb, ΔHbO2, and ΔdeoxyHb on the infarct side in response to HOB elevation. Our study participants received magnetic resonance angiography (MRA) at the time of admission and 7–10 days after stroke onset. MRA often cannot provide information about the collateral circulation of AIS patients in clinical settings because of motion artifacts and its spatial resolution, whereas recent development of MRA can detect collateral circulation in research settings [2 correlates with cerebral capillary oxygen saturation [Correlations of ΔtHb, ΔHbOerritory . It is aerritory ,32,33. Ierritory . Althougsettings ,36. Furtsettings ,38. Convsettings , and measettings ,41. Recesettings ,43,44,45turation ,46,47,48turation ,24,49. Tturation . Thus, w2) or partial pressure of carbon dioxide (pCO2). It is known that CBF is influenced by CO2, and hypercapnia dilates cerebral arteries and arterioles and increased blood flow, whereas hypocapnia causes vasoconstriction and decreased blood flow [2 from 40 mmHg to 35 mg in elder subjects [2 could also affect NIRS metrics. Fourth, we did not assess cerebral autoregulation or differences in the CBV responses among NIRS and other modalities . Thus, we could not offer reasons why a statistically significant correlation of changes in cerebral oxygenation parameters between each hemisphere in response to HOB manipulation was found at 7–10 days after AIS onset but not within 72 h.This study has several limitations. The monitored systemic blood pressure and heart rate were not beat-to-beat measurements. Thus, we could not detect a transient drop in blood pressure in response to HOB manipulation. Lam et al. reported that the blood pressure may show a steep drop in response to gradual changes in head position (supine to 30°), although a blood pressure decline was observed in the head-up state . Furtherood flow ,52. Indesubjects . TherefoHOB manipulation from 0° to 30° did not affect cohort-averaged hemodynamic parameters. The cohort-averaged cerebral oxygenation parameters also did not change in response to HOB elevation, although large interindividual cerebral oxygenation changes were seen. Although changes in cerebral oxygenation in response to HOB elevation had a laterality difference between the hemispheres within 72 h of AIS onset, the difference decreased, at least partially, 7–10 days after AIS onset, and this could have suggested a sign of cerebral blood flow recovery. These findings suggest that HOB 30° within 72 h might not always be a preferred head position in AIS patients. Further studies are needed to establish the safety and efficacy of NIRS-guided neurological rehabilitation in AIS in the future.


Valuable information about cardiovascular system can be derived from the shape ofaortic pulse wave being the result of reciprocal interaction between heart andvasculature. Pressure profiles in ascending aorta were obtained from peripheralwaveforms recorded non-invasively  before,during and after hemodialysis sessions performed after 3-day and 2-dayinterdialytic intervals in 35 anuric, prevalent hemodialysis patients. Fluidstatus was assessed by Body Composition Monitor  and online hematocrit monitoring device . Systolic pressure and ejection duration decreased duringdialysis. Augmentation index remained stable at 30 ± 13% throughout hemodialysissession despite the decrease of augmented pressure and pulse height.Subendocardial viability ratio (SEVR) determined after 3-day and 2-dayinterdialytic intervals increased during the sessions by 43.8 ± 26.6% and 26.1 ±25.4%, respectively. Hemodialysis performed after 3-day and 2-day interdialyticperiods reduced significantly overhydration by 2.4 ± 1.0 L and 1.8 ± 1.2 L andblood volume by 16.3 ± 9.7% and 13.7 ± 8.9%, respectively. Intradialyticincrease of SEVR correlated with ultrafiltration rate , reduction in overhydration  and bloodvolume drop . The strong correlation between thedecrease of overhydration during hemodialysis and increase in SEVR confirmedthat careful fluid management is crucial for proper cardiac function.Hemodialysis affected cardiovascular system with the parameters derived frompulse-wave-analysis  being significantly different at the end of dialysis from thosebefore the session. Combination of pulse-wave-analysis with the monitoring ofoverhydration provides a new insight into the impact of hemodialysis oncardiovascular system. The relationship between chronic kidney disease (CKD) and cardiovascular disease isbidirectional ,2. CardiWith every heartbeat the left ventricle generates pulse (pressure) wave that travelsthrough the arterial tree. Multiple bifurcation points, variable vessel diameter,presence of a plaque, and varying wall elasticity affect the arterial pressurewaveform. ,9. The sCardiovascular system of a standard hemodialysis patient is under the constantinfluence of many non-physiological factors. During 2–3 days of interdialytic periodpatient gains 2–3 L of water that is quickly removed during 4-hour hemodialysistypically performed 3 times per week. Blood flow in extracorporeal circuit duringhemodialysis and non-physiologic connection of the vessels of arteriovenous fistulaalso affect the cardiovascular system. Blood volume and blood pressure decreaseduring hemodialysis. Hemodialysis is a lifesaving treatment, but at the same time itexerts a considerable load on the cardiovascular system.The purpose of this study was to assess the impact of different phases ofhemodialysis on cardiovascular system by the analysis of pulse wave recorded before,during and after hemodialysis. Parameters derived from the aortic pressure waveformwere related to the changes in overhydration and blood volume duringhemodialysis.The study has been conducted according to the principles expressed in theDeclaration of Helsinki, was approved by the Bioethical Committee at the MedicalUniversity of Lublin (Poland) and written informed consent was obtained fromeach patient.2, 2),ultrafiltration coefficient (mL/h x mmHg) and sterilization method were:polysulfone based, 1.8, 59, inline steam in 12 patients; polysulfone based, 1.6,16, inline steam in 6 patients; polyethersulfone composition, 1.7, 18, Gamma-rayin 6 patients; polysulfone based, 2.1, 17, Gamma-ray in 4 patients; polysulfonebased, 1.6, 6.4, ethylene oxide in 4 patients; and polyamix, 2.1, 15, steamin 3 patients, respectively. The average flow of blood and dialysis fluid was287.3 ± 47.4 mL/min (range 180–380 mL/min) and 500 mL/min, respectively. Allpatients had arteriovenous fistulas.Two standard bicarbonate hemodialysis sessions (duration 240.2 ± 13.4 min) weremonitored in 35 anuric, prevalent hemodialysis patients  was chosen. Measurements withinsufficient quality (‘operator index’ ≤ 74) were excludedaccording to the producer’s indication. All recordings were performed by onetrained clinician in the non-fistula arm. The radial pulse wave was calibratedto the blood pressure measured oscillometrically at brachial artery . The aortic pulse pressure waveform was derivedfrom the recorded peripheral waveform using the generalized transfer functionthrough the built-in device software, Pulse wave shape in radial artery was recorded using applanation tonometry before the start, after the start, beforethe end, and after the end of two hemodialysis sessions performed after 3- and2-day interdialytic intervals in patients in restful state, Augmentation index was determined as augmented pressure (AP) over pressure height(PH), AI = AP/PH·100% with PH being the difference between aortic systolic (SBP)and diastolic (DBP) pressures (PH = SBP–DBP), Ejection duration (ED) is the time from the start of the pulse to the closure ofthe aortic valve that determines the end of systole. Ejection duration togetherwith diastolic time (DD) constitute the period, which is the inverse of heartrate (HR), SEVR–subendocardial viability ratio–was defined as diastolic time index (DTI)over tension time index (TTI): SEVR = DTI/TTI with DTI = meanDBP·DD·HR and TTI =meanSBP·ED·HR, where meanDBP and meanSBP are average aortic pressures duringdiastole and systole, respectively. Geometrically, SEVR can be determined as thediastolic area over systolic area of aortic pulse pressure, Fluid status was assessed by whole-body bioimpedance . Overhydration, extracellular,intracellular and total body water (being the sum of extra- and intra-cellularvolumes) were measured before and after each hemodialysis session .Relative changes of blood volume were measured by online monitor  during both hemodialysis sessions after 3-day and 2-dayinterdialytic periods. The volume of blood (BV) at the end of dialysis wascalculated using an anthropometric formula  [The data are presented as mean ± standard deviation (SD) and statisticalsignificance was set at the level of p-value < 0.05, unless otherwiseindicated. Statistical dependence between variables was tested using Spearman’scorrelation coefficient (R). Multiple comparisons were investigated byWittkowski test followed by multiple pairwise comparison analysis based onadjusted Scheffe’s procedure. Wittkowski test is a Friedman-type statistics forconsistent multiple comparisons for unbalanced designs with missing data . In our SBP) of 9.7%, aortic end systolic pressure (ESP) of11%, pressure at the inflection point (IP) of 11.8%, and estimated ejectionduration (ED) of 13.6%, Hemodialysis did not affect the heart rate which had a stable average value of 69± 12 beats/min. No hemodialysis-related changes were detected in brachial andaortic diastolic blood pressures with averages 73.7 ± 13.2 mmHg and 74.5 ± 13.2mmHg, respectively, The augmented pressure (AP) and pulse height (PH) decreased during hemodialysisby 34.4 ± 53.2% and 26.4 ± 24.5%, respectively Figs  and 3, bSEVR determined after 3-day and 2-day interdialytic intervals increased duringthe session by 43.8 ± 26.6% and 26.1 ± 25.4%, respectively  and dropped afterhemodialysis by 13.9 ± 10.1% and 10.1 ± 12.3%; nevertheless, it wassignificantly higher than before the start of dialysis, The set ultrafiltration volumes were 2.96 ± 0.73 L and 2.35 ± 0.97 L forhemodialysis sessions carried out after 3-day and 2-day interdialytic intervals, what corresponded to ultrafiltration rates of 12.33 ± 2.94mL/min and 9.73 ± 3.85 mL/min, respectively. Hemodialysis performed after 3-dayand 2-day interdialytic periods reduced overhydration by 2.4 ± 1.0 L and 1.8 ±1.2 L , respectively, as assessed by body compositionmonitor; and blood volume decreased by 16.3 ± 9.7% and 13.7 ± 8.9% , respectively, Changes of SEVR correlated negatively with changes in overhydration  when considering difference between values after vs. beforehemodialysis, The pulse wave analysis (PWA) technique is a non-invasive and useful tool toinvestigate the cardiovascular state. The accuracy of the PWA estimated aortic bloodpressure was validated but also questioned by some studies ,33–37. OWe observed the most pronounced changes in PWA-derived parameters when comparingmeasurements performed before the start and before the end of hemodialysis session.This behavior is clearly visible in SEVR value, which was the smallest beforehemodialysis with the highest value before hemodialysis termination, We did not observe the statistically significant differences between the patientparameters measured after 3-day vs. 2-day breaks (except for weight), although thechange in numerical values were in agreement with intuitive expectation, Hemodialysis affected myocardial perfusion assessed by SEVR–subendocardial viabilityratio–that is considered an estimate of subendocardial oxygen supply related tooxygen demand ,24,42. PTwo recent studies showed, however, a decrease in myocardial perfusion duringhemodialysis ,46. MyocWhy SEVR increases considerably during dialysis? SEVR is the ratio of diastolic timeindex, DTI, and tension time index, TTI, see SBP) and ejection duration (ED)decreased, whereas diastolic duration (DD) increased and period (1/HR) remainedunchanged. Augmentation index (AI) did not change during the session. Intradialyticincrease in SEVR–subendocardial viability ratio–correlated with ultrafiltrationrate, the reduction in overhydration (OH) and blood volume (BV). During hemodialysissession we traced and discussed components of SEVR showing significant decrease ofthe tension time index (TTI—the area under the curve of aortic pressure duringsystole) and stable value of diastolic time index (DTI–the area of aortic pressureduring diastole). The estimation of SEVR from the aortic waveform is of importancefor clinical monitoring of patients as an unfavorable imbalance between oxygensupply and demand may reduce heart perfusion below a critical value. A limitation ofour study is the lack of comparison between SEVR and its components with analternative method able to assess myocardium during hemodialysis. Several essentialparameters derived from pulse wave registered shortly before the end of hemodialysiswere considerably different from those before the session, however, after the end ofhemodialysis the cardiovascular system had tendency to return towards thepre-dialysis state. Pulse wave analysis combined with the monitoring of body fluidhave the potential to be a diagnostic tool to assess the impact of hemodialysis onthe cardiovascular system.In conclusion, the profile of pressure wave in aorta is the result ofventricular-arterial interaction and is a reliable source of information aboutcardiovascular system. This study is the first to provide the comprehensive analysisof parameters derived from pulse-wave-analysis and their changes caused byhemodialysis treatment. We show the significant decrease of systolic (SBP), endsystolic (ESP), augmented pressures (AP) and pulse height (PH) during hemodialysis.Time of the systolic pressure peak (tS1 Table(DOCX)Click here for additional data file.


ECF) excess is an independent predictor of cardiovascular morbidity in patients undergoing dialysis. This study aimed to investigate the relationship between ECF status, which is affected by renal function, and coronary artery calcification (CAC), which is a marker of cardiovascular disease, in patients with chronic kidney disease (CKD).Extracellular fluid  were analyzed for the association between ECF status and CAC. ECF status was defined as extracellular water‐to‐total body water ratio (ECW/TBW) measured using bioelectrical impedance analysis. ECF excess was defined as ECW/TBW ≥0.390 or ≥0.400 depending on its severity. To define CAC, Agatston coronary artery calcium scores were measured. A total coronary artery calcium score of ≥400 was defined as CAC. The CKD stages were defined according to estimated glomerular filtration rate calculated using the CKD Epidemiology Collaboration equation. ECW/TBW and the proportion of ECF excess increased with progressing CKD stages. Multivariable logistic regression analyses showed that ECW/TBW was independently associated with CAC . The adjusted R2 for predicting higher coronary artery calcium scores and CAC significantly improved after ECW/TBW was added to conventional factors. This association was further confirmed by net reclassification and integrated discriminant improvements, sensitivity analysis, and subgroup analysis.A total of 1741 patients at all stages of pre‐dialysis ECF status is independently associated with a high risk of CAC in patients with CKD.URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02003781. Extracellular fluid status deteriorated with declining renal function and was independently associated with a high risk of coronary artery calcification in patients with chronic kidney disease.Our large‐scale study is the first to identify extracellular fluid excess as a nontraditional factor associated with coronary artery calcification in patients at all stages of chronic kidney disease.Extracellular fluid status may be a contributing factor to the development of coronary artery calcification in patients with chronic kidney disease.Our study provides a basis for further investigations to determine the direct effect of extracellular fluid status on the pathogenesis of coronary artery calcification.An increasing number of studies have demonstrated that cardiovascular disease is the primary cause of morbidity and mortality in chronic kidney disease (CKD).Extracellular fluid (ECF) excess is a common condition in patients with advanced CKD and undergoing dialysis, and previous studies have shown that ECF excess is associated with all‐cause mortality and cardiovascular morbidity.The clinical assessment of ECF status is relatively difficult because the physical signs of edema are of limited value in diagnosing excess intravascular volume and tissue hydration status.Thus, we conducted this cross‐sectional study to investigate the association between exacerbated ECF status, which occurs with renal function deterioration, and coronary artery calcification (CAC), which is an indicator of cardiovascular disease, in patients at all stages of CKD.The authors declare that all supporting data are available within the article and its online supplementary files.This study was conducted in accordance with the Declaration of Helsinki, and the study protocol was approved by the institutional review board at Yonsei University Health System Clinical Trial Center. All patients provided written informed consent before entering the study .https://clinicaltrials.gov/NCT02003781 (Cardiovascular and Metabolic Diseases Etiology Research Center‐High Risk Cohort) study of the Yonsei University Health System between November 2013 and May 2017. CMERC‐HI is an ongoing, nationwide, and prospective cohort study that included patients at a high risk for cardiovascular disease at the Yonsei University Health System, designed to establish an individualized preventive strategy for cardiovascular and cerebrovascular diseases. The following participants were eligible for inclusion in CMERC‐HI: patients with a high risk for hypertension, namely, hypertensive patients with an estimated glomerular filtration rate (eGFR) of ≥60 mL/min per 1.73 m2 and target organ damage, or hypertensive patients with eGFR <60 mL/min per 1.73 m2; diabetic patients with a random urine albumin‐to‐creatinine ratio of ≥30 mg/g; patients with end‐stage renal disease undergoing dialysis; relatives of patients who have acute myocardial infarction and who were younger than 55 years (for men) or 65 years (for women); patients with asymptomatic atherosclerotic cardiovascular disease ; patients aged >40 years with rheumatic arthritis and taking methotrexate and steroid; patients with atrial fibrillation with CHA2DS2‐VASc score ≥1; and kidney transplant recipients who underwent transplantation >3 months previously. The exclusion criteria were as follows: acute myocardial infarction history  or acute coronary syndrome (unstable angina), symptomatic peripheral artery disease, symptomatic heart failure, life expectancy <6 months or severe noncardiovascular disease , and pregnancy or breastfeeding.The subjects were selected from the CMERC‐HI, registration number for study on From the total of 2367 patients enrolled in the CMERC‐HI study, we further excluded patients with end‐stage renal disease undergoing dialysis or kidney transplantation, those without BIA data, and those without coronary artery calcium scores (CACSs). Finally, a total of 1741 patients were analyzed for our study  at the time of enrollment. A direct segmental multifrequency BIA method was used with a tetra‐polar 8‐point tactile electrode system, with 30 impedance measurements obtained using 6 frequencies. High‐frequency current passes through the total body water (TBW), whereas low‐frequency current cannot penetrate cell membranes and thus flows exclusively through the extracellular water (ECW). On the basis of a fluid model with these resistances, the ECW, intracellular water, and TBW were calculated. According to the concept that excess ECW results in edema, ECF status was defined as the ECW‐to‐TBW ratio (ECW/TBW), and ECF excess was classified as follows: mild overhydrated state (ECW/TBW 0.390–0.399) and moderate to severe overhydrated state (ECW/TBW ≥0.400) .All examinations were performed with a 320‐row computed tomography system  with subjects in the supine position on a table, and images were acquired during a single breath hold, to allow image reconstruction in a single cardiac phase. Dual scanograms were used for planning the examination and determining the anatomical range. To obtain the CACSs, a nonenhanced prospective ECG‐gated scan was performed with the following parameters: rotation time, 275 ms; slice collimation, 0.5 mm; slice width, 3.0 mm; tube voltage, 100 kV; and automatic tube current modulation. Images were analyzed in a core workstation with dedicated software . Agatston calcium scores were calculated to quantify the extent of CAC. A total CACS of ≥400 was defined as CAC.Clinical data and laboratory parameters were collected at the time of cohort enrollment. Diabetes mellitus was defined as a history of diabetes mellitus, use of antidiabetic medications, or fasting plasma glucose levels >126 mg/dL; hypertension was defined as a self‐reported history of hypertension, a history of antihypertensive medication use, or a blood pressure of 140/90 mm Hg or higher at the time of visit; and cardiovascular disease was defined as a composite of coronary occlusive disease, ischemic heart disease, congestive heart failure, atrial fibrillation, atherosclerosis, and cerebrovascular disease. Medications including antihypertensive and antidiabetic drugs and diuretics were investigated based on prescriptions at the time of enrollment. Height, weight, body mass index, and anthropometric data were measured. Moreover, 24‐hour ambulatory blood pressure monitoring was performed using a Takeda TM‐2430 instrument . The pulse pressure measured with 24‐hour ambulatory blood pressure monitoring was used in this analysis. Lipid profile components and glucose levels were measured in blood samples obtained after a 12‐hour fast. The eGFR was calculated according to the CKD Epidemiology Collaboration equation based on serum creatinine level.2 test was used for categorical variables. Mantel–Haenszel linear‐by‐linear association method and Jonckheere–Terpstra test were used for analyzing trends. A linear regression analysis was used to identify factors associated with ECF status. To evaluate the independent association of ECF status with CAC, a logistic regression analysis was performed. Factors significantly associated with CAC in the univariate logistic regression analysis (P<0.05) were included preferentially in the multivariable logistic analysis. Also, factors independently associated with ECW/TBW in multivariable linear regression analysis were considered as covariates in multivariable logistic analysis. Factors such as serum calcium and phosphate levels and hypertension history were also included in the multivariable model because of its established significance with CAC despite the lack of statistical significance in our results.Continuous variables were expressed as the mean and SD or median with interquartile ranges, and categorical data were presented as counts with percentages. The normality of distribution was ascertained with the Kolmogorov–Smirnov test, Shapiro–Wilk test, and histogram analysis, and skewed continuous parameters were logarithmically transformed before use in parametric procedures. To compare among several groups, analysis of variance with Bonferroni correction or the Kruskal–Wallis test was used for continuous variables, and the χAll analyses were performed with SPSS statistical software version 23.0 , GraphPad Prism version 5.0 , and R language  including the smoothHR, pspline, pROC, and PredictABLE packages.P for trend <0.001). As CKD progressed, the proportion of patients with ECF excess tended to increase, and the same tendency was observed in patients with mild‐to‐severe overhydrated status (ECW/TBW ≥0.390) and those with moderate‐to‐severe overhydrated status (ECW/TBW ≥0.400)  Figure B.2. The mean ECW/TBW was 0.386, and the values according to groups were 0.374, 0.382, 0.388, and 0.400 (first to fourth quartile). The median CACS was 22.0 (0.0–189.3), and 14.4% patients had CAC. Exacerbating ECF status, expressed in quartile range, was significantly associated with CACSs and the percentage of CAC. Baseline characteristics according to CKD stage are shown in Table Table In multivariable linear regression to assess the association of ECW/TBW with variables that were significantly correlated with ECW/TBW in univariable linear regression analysis Table , CACS waP<0.001). Cubic spline plots showed that the risk of CAC increased steadily with exacerbating ECF status   Figure .P=0.004; continuous NRI=0.571, P<0.001) and IDI   Table . This fiP<0.001).For sensitivity analyses, we further analyzed the association between ECF and CACSs as well as the presence of CAC. In univariate and multivariate analyses, ECF status was statistically significantly associated with log‐transformed CACSs (model 3 in Table P<0.001)  Table .P=0.003) and the group with diabetes mellitus with albuminuria . In the group with cardiovascular disease, ECF status was also associated with CAC, but not statistically significantly , and supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT and Future Planning (NRF‐2015R1A2A2A01007346).None.Table S1. Baseline Characteristics According to CKD StagesTable S2. Univariate Linear Regression Analysis of Variables Associated With Extracellular Fluid StatusTable S3. Univariable Logistic Regression Analyses for Presence of Coronary Artery Calcification*Table S4. Reclassification Improvement for Presence of Coronary Artery Calcification* by Extracellular Fluid StatusTable S5. Unadjusted and Adjusted Linear Regression Analyses of Extracellular Fluid Status for the Coronary Artery Calcium Scores*Table S6. Association of ECF Status for the Presence of Coronary Artery Calcification* After Additional Adjustment of NT‐proBNPTable S7. Subgroup AnalysisTable S8. Unadjusted and Adjusted Odds Ratios of Extracellular Fluid Status for the Presence of Coronary Artery Calcification* Stratified by the Severity of Chronic Kidney DiseaseTable S9. Association of ECF Status for the Presence of Coronary Artery Calcification* Depending on Diuretic UseClick here for additional data file.