To the Editor,We would like to commend Moussa et al. for their work recently published in Critical Care  in whichAlthough we think, as the authors, that the harmful effect of hyperoxemia in these very sick patients exposed to ischemia and reperfusion is probable, we would like to discuss some possible confounding factors.aO2 is determined by both SvO2, hemoglobin concentration, native lung function, inspired oxygen fraction on ventilator (FIO2), positive end expiratory pressure, sweep gas oxygen fraction (FSO2), and the balance between native cardiac function and ECMO blood flow. The later determines the mixing zone location, i.e., the zone in the aorta where the blood ejected from the heart and oxygenated by the lungs meets the blood ejected and oxygenated by the ECMO [POSTO2) can rise to 500 mmHg. Then, hyperoxemic patients might be those for whom right arm PaO2 is mainly determined by the ECMO when the mixing zone is in the aortic arch close to the brachiocephalic trunk. Such situation might occur in case of high ECMO blood flow and severe cardiac failure, which could lead per se to a poor prognosis.First, the association between right arm hyperoxemia and prognosis reported in observational studies might be impacted by the native cardiac function. Indeed, during femoro-femoral VA-ECMO, the right arm PaO2 on admission. Although they did not find any association, we cannot rule out that mean daily peak PaO2, absolute peak PaO2, and overall mean PaO2 could be associated with ECMO blood flow. It could be also of interest to test the association between right arm PaO2 and surrogates of native cardiac function, such as pulse pressure or end tidal CO2 [To explore this possibility, the authors have tested the interaction between ECMO blood flow and right arm Pidal CO2 .IO2” corresponds to the inspired oxygen fraction on the ventilator, or to the FSO2 set on the ECMO. It could be of interest to precise both FIO2 and FSO2. If “FIO2” actually corresponds to FSO2, we can hypothesize that PPOSTO2 was higher in non-survivors than in survivors, which potentially has resulted in more reperfusion injury of intra-abdominal organs mediated by radical oxygen species [Another way to support the causality link between hyperoxemia and poor prognosis is to demonstrate that exposition to oxygen is different between survivors and non-survivors. In Table 2, it is unclear if the “F species .aO2 reflect different oxygen exposure. Indeed, overall mean PaO2 is mathematically linked to the number of ABG sampled. If several ABG analyses are performed during a short period of hyperoxemia, overall mean PaO2 could overestimate oxygen exposure. Assuming that the most severe patients have more frequent ABG analysis, we cannot exclude that overall mean PaO2 could overestimate oxygen exposure in most severe patients. Then, it could be of interest to determine the relation between 28-day mortality and time-weighted PaO2 [aO2.Finally, the number of arterial blood gas (ABG) analysis performed during the 48 first hours of VA-ECMO support might be an interesting data to show to ensure that different overall mean Pted PaO2 , a metriBeyond these points of discussion, Moussa et al. have to be congratulated for their work which adds rationale for the two ongoing randomized trials on oxygen management during VA-ECMO support . Dear Dr Winiszewski,We would like to thank Dr Winiszewski and colleagues for their comments that raises one of the major question regarding the management of peripheral veno-arterial ECMO (VA-ECMO)—“What are the determinants of arterial oxygenation in patients receiving VA-ECMO support?”. Numerous studies have attempted to answer this question, but data are limited for VA-ECMO patients and are even more limited when only patients in cardiogenic shock are considered (excluding eCPR). Retrograde arterial blood flow and mixed blood flow zone phenomena exist only in the VA-ECMO settings, which do not allow extrapolation of data from VV to VA-ECMO.2 measured at the right arm level are the blood flow delivered by the VA-ECMO and the sweep gas oxygen fraction. None of the ventilator parameters  were associated with right arm PaO2. Furthermore, this study demonstrated that during the initial phase of VA-ECMO support, the impact of the native heart function could be neglected and was not related to PaO2. Indeed, the participation of the native cardiac function on the PaO2 is modulated by the level of VA-ECMO assistance. The greater the level of VA-ECMO support, the lower the contribution of the native cardiac function. However, we usually observe during the initial phase of refractory cardiogenic shock a collapsed native heart function and a high level of VA-ECMO support , which suppresses the influence of the native heart on PaO2. This may also explain why pulse pressure, which is largely determined by the native heart function, is not associated with right arm PaO2. Thus, at the start of VA-ECMO support, an elevated right arm PaO2 may often reflect hyperoxemia throughout the body. Because our study focused on the early period of VA-ECMO support, we believe that we have avoided these confounding factors.Andrei and colleagues  recently2 may better reflect the time of exposure to hyperoxemia than two time points over a 24-h period, but this remain difficult to use in clinical practice. All patients underwent arterial blood gases according to the local centers' “standard of care”, so that we can assume that a quite similar number of PaO2 measurements were obtained in each patient.We agree that the time-weighted PaOThis method is far from perfect, but it is clinically relevant and close to what is reported in previous studies evaluating hyperoxemia .In summary, despite these limitations that were already discussed  and base


Goal: To provide a Multiple Emergency Ventilator (MEV) as backup in case of shortage of ICU ventilators and for use in camp hospitals. Methods: MEV provides the same oxygen mixture and peak inspiratory pressure (PIP) to 10 patients. These specifications were fixed: i) gas supply and plugs to double-limb intubation sets compatible to existing systems; ii) fluid-dynamics with no pressure drop and almost complete patients’ uncoupling; iii) individual monitoring of inspiratory and expiratory pressures and flows and control of their timing; iv) easy stocking, transport, installation with self-supporting pipes. Results: A Bell-Jar System (BJS) design permitted to safely fix PIP based on Archimedes’ law. The main distribution line was based on 2” stainless steel pipes assuring the required mechanical properties and over-dimensioned for fluidics. The Windkessel of the BJS and pipeline dead-volumes is 75.65 L and in the worst case of the instantaneous demand of 5 L by 10 patients (0.5 L each) shows an adiabatic PIP drop limited to –6.18%, confirming the needed uncoupling. Consequently, patients’ asynchrony is permitted as needed by pressure-controlled volume-guaranteed and assisted-ventilation. Conclusions: Although MEV is proposed as a backup system, its features may cover the whole set of ventilation modes required by ICU ventilation. I.As The COVID-19 pandemic was growing fast also the need for ICU ventilators stepped on. Unforeseen efforts were dedicated by research and industry to increase the number of ventilators and also to multiply the number of patients assisted by a single one by some adaptation at the patients’ end. However, medical societies and regulatory agencies in the US The Multiple Emergency Ventilator (MEV) proposed here was conceived on a totally different principle. Indeed, the mere adaptation of formerly existent equipment suffers from the intrinsic flow limitation of single patient ventilators and also is prone to uncontrolled flow partition to the two or more patients with different and unpredictable respiratory system properties. The cited regulations MEV strength resides in being purposely designed and dimensioned to safely assist 10 patients by positive pressure ventilation with oxygen mixture, concentrating and simplifying the major pressure control issues into a single common element, which was identified in a water sealed bell-jar system (BJS). In this way the peak inspiratory pressure (PIP) is intrinsically limited at (or slightly below) the BJS pressure, which in turn is intrinsically fixed by Archimedes’ law. High simplification of the single patient lines is permitted by the common pressure drive and by the distribution system allowing a full uncoupling among patients assisted in parallel. This feature was enhanced by the high over-dimensioning of the distribution pipe (2”), which also allows the wanted mechanical properties needed in an emergency environment: easy storing and assembling, self-supporting and support to all the related devices .It is due stating that MEV is proposed as a backup choice in emergency conditions, while single patient ventilators firmly remain the first option. Nonetheless, the recently passed COVID-19 peak has shown how the limits to cover the rising phase of crisis can be rapidly reached, even in western Countries. Also, new crises can be foreseen in this pandemic if vision is dutifully enlarged to developing Countries and to emergency conditions Indeed, the parallel option is to maintain huge reserves of ventilators with current design II.In the first few days of work, the backbone of MEV was conceived with maximum simplification and functions limited to pressure-controlled ventilation, to be deployed to assist severely dyspneic patients waiting for a fully equipped ICU bed, potentially for several hours, given the rising load of these departments. Soon, we understood that the intrinsic volume buffering of MEV (see Results) permitted a decoupling of patients’ lines sufficient to permit higher level asynchronous functions such as assisted ventilation on each patient's demand. The enhanced version, here presented, is referred to as MEVplus in our internal open report A.S1)2 concentration (FiO2) necessarily equal for all patients, though adaptable to average needs.Inflow OS2)PIP necessarily equal to all patients, yet easily adaptable.S3)Adoption of an intrinsically safe physical principle determining PIP against accidental barotrauma.S4)Robust and simple design of the core element (BJS).S5)2-compatible elements.Dimensioning of gas supply and distribution for up to 10 patients; all by OS6)Negligible dynamic pressure drops in the common distribution line.S7)Self-supporting gas distribution system , giving an easy mounted support to all devices.S8)Easy stocking, transport, installation, and maintenance.S9)Flexible layout, fitting to any ambient shape.S10)Individual expiration lines with adaptable PEEP device.S11)Plug of standard double-limb intubation sets.S12)Personalized ventilation timing, with a negligible pressure drop in the worst case of a simultaneous inspiration by all patients.S13)Wide range of ventilation modes, from controlled to assisted ventilation.S14)Adoption of off-the-shelf components, whenever possible.The driving design specifications are listed below and referred next  in Results.In addition, prevention of cross infections by viral and bacterial agents is a core issue. MEV countermeasures are: i) each patient connected to a standard disposable ventilator circuit; ii) individual inspiration and expiration lines, the latter separated from the distribution system; iii) a nonreturn valve at both the inspiration and expiration ends; iv) easy dismantling of both lines for sanitization. No segmentation is conversely foreseen for the common 2” line; hence, the absence of back contamination via the inspiratory line should be attentively checked on the future prototype tests.B.Interdisciplinary cooperation coordinated by a Biomedical Engineer (G.B.) and to an Intensive Care MD (A.Z.). CAD of special parts was on two Mechanical Engineers . System fluid-dynamics and intrinsic safety feature were on a Bio-Mechanical Engineer (G.B.F.). System and control simulations were carried out by an Automation Engineer . Focus onto the potential compliance with ICU clinical standards (to be tested and approved in the future development of MEV) was kept (A.P. and A.Z.).C.The model for system simulations was implemented in the Modelica language R = 6÷18 cmH20/(L/s) and lung compliance in the range C = 0.03÷0.06 L/cmH20. The equivalent of the series of patient valves and pressure/flow measurement tools was simulated by a single valve flow coefficient vK=1.8 m3/h. The flow-dynamics of all distribution elements were modelled accounting for adiabatic compressibility (with coefficient γ = 1.4 for diatomic gas at room temperature) and friction effects, see Results. Tidal volumes ranging from 0.3 to 0.5 L were obtained, with RR ranging from 14 to 30 acts/min, depending on the patient conditions. Appropriate duty cycles were set to obtain the desired tidal volumes.The main body results present only the not recommended, most critical case of synchronous inspiration by 10 patients with non-restricted lung capacities to challenge decoupling capabilities (S12). Patients with different clinical conditions are considered, with airways resistance in the range III.iO2 as well as medical gas conditioning (S1) was not part of the project. Plug was assumed to standard medical gas lines  and gas conditioning.FA.2 mixture distribution, its mechanical support, and the main controls. The core supply element (S2-S5) is the water sealed BJS, detailed in 2, which requires a bell-mass of 28 kg to provide the nominal PIP = 24 cmH2O. By subtracting the movable weights  in order to assure visual check of the water seal levels and hence of PIP.2O , plus 1 cmH2O margin to the safety gas escape. Accordingly, a 24 cm level gap is shown between the internal water-seal level and the higher external one . Importantly, higher pressure values would result in a water-sealing loss, with the BJS O2 bubbling outside, thus assuring intrinsic safety and protection against barotrauma. Rising the operative range  to 30 cmH2O implies increasing the BJS height dimensions by 6 cm.The dynamic range was fixed to ±10 liters (L), thus ±8.6 cm. The redundant BJS dead volume (59 L) was reduced by the central sealed element  to 15.27 L. The narrower cylinder at the sealed element top creates a water-trap preventing accidental water leakage to the core connector (blue).B.Distribution , S5-S9 wThe common gas supply to the BJS was dimensioned to 4 L/s maximum, which permits sufficient supply even in the case of the accidental detachment of a patient. For ergonomic reasons, the recommended installation is: i) female end of any element upstream; ii) the 20 cm T-element at the right bed-side, hence upstream to the 200 cm element. Additional connector and special elements are foreseen for the 2” distribution: short connectors with manual shutter to exclude the downstream distribution limb for maintenance; several sizes of linear elements ; bows (90° and 45°); 20 cm element with water trap. Finally, a central cross element splits the inflow to three orthogonal lines which may be shut or active thus permitting the several layouts shown in C.As said in the previous Par., the inspiration line is screwed  to a T-shaped element of the main line. It includes the series: i) inspiration/expiration switch valve, ii) flowmeter (not shown), iii) pressure meter (not shown), iv) one-way valve (not shown), and v) a standard 22 mm connector to the patient's intubation set.Each independent expiration line (S10) is gripped (not connected) to the 2” pipe, at the right end of the 200 cm. It includes the series of: i) 22 mm plug to the intubation set, ii) one-way valve, iii) pressure meter, iv) flow-meter, v) switch valve, and vi) a standard adaptable PEEP element. It is recommended to collect the expired air by a vent line, properly dimensioned not to add overpressures to PEEP.Plugging to standard double-limb patient sets (S11) imposed to have no element common to the inspiration and the expiration line; accordingly, inspiration/expiration change by a single three-way valve was forbidden. Thus, the two mentioned switch valves were inserted to be opened and closed in counterphase , the worst case is the synchronous inspiration of 10 patients summarized below. Even more severe is an instantaneous adiabatic expansion. Though purely theoretical, it permits to set a lower bound to PIP drops, independent from patients resistive and capacitive features and the dynamic compensation by the BJS. We start from the system dead-volume of 75.92 L summing up: i) the 15.27 L of BJS dead volume; ii) the 10 L from BJS set-point to its minimum level; iii) 50.65 L of the 2” distribution system (25 m times 2.03 L/m). An adiabatic expansion (γ = 1.4) of 5 L (0.5 L per patient) to 80.92 L gave a pressure drop from 24 to 22.52 cmHA more realistic simulation of the synchronous worst case, including all the fluid-dynamic elements, is here summarized (see SM-C for details). During inspiration, lung volume curves reach their 0.5 L target in less than 0.75 s, with the farthest patient receiving 8% less volume, which could be easily compensated by slightly increasing the duty cycle.2O after 30 ms from the valve opening, and gets back to 24 cmH2O within 100 ms. Patient #10 supply pressure drops to 18.5 cm H2O after 40 ms, recovering to 22.5 cmH2O after 100 ms, and then recovering the full PIP by the end of the inspiration act. The efficiency of the BJS pressure stabilization was demonstrated by a bell-level drop limited to –3.5 cm, safely away from the –8.6 cm lower bound.Transient pressure dips at the inspiratory line inlets are also limited. Patient #1 supply pressure reaches a minimum of 19.5 cmHThe above noticeable results permitted to consider the advanced and adaptable ventilation modes (S13) needed during the whole course of invasive ventilation, starting with controlled and ending with assisted modes IV.A.primum non nocere . The described design features also allow quick placement in almost any indoor or room or outdoor camp hospital mounting robust pieces, all passive, robust to transport or long stockage. Off-the shelf components As depicted by the graphical abstracts, in a pandemic crisis the need of ICU beds may rapidly rise, as unfortunately demonstrated by COVID-19. Facing a lack of ventilators, MEV may, at least temporarily, cover this necessity. Its intrinsically safe low-pressure distribution system avoids compromises as to patients’ safety: After one year since the COVID-19 pandemic burst, its spread-out has been by far more dramatic than it could be envisaged starting this work. So far, focus has been on urgent issues such as infection spread prevention, collection of the currently available equipment, and, most importantly, the availability of trained intensive care personnel as well as therapies and vaccines. Conversely, the development of new ventilation technologies, even auxiliary ones as MEV, has been seemingly too slow to face the recent pandemic phases. Despite eminent and early issued indications of risk The proposed MEV aims at overcoming the limits of ventilator sharing: i) power and flow under-dimensioned on a single patient basis; ii) extensive fluid-dynamic coupling; iii) identical ventilation mode and timing; iv) shared ventilation monitoring and limitations in individual alarming; v) high cross contamination risks. Fixed PIP and FiO2 are, conversely, common limits of both the MEV and shared ventilator approaches, while PEEP can be individually adapted in both systems. However, a novel device as MEV will have to undergo all the necessary development phases: engineering, technological transfer, validation, and approval for medical use. So, authors are stressing that the presented results are just a promising starting point. The major result of patients’ uncoupling is also easing the foreseen monitoring and control features as summarized in SM-A.MEV was dimensioned for 10 patients mainly to have a group suited to the surveillance by a single medical staff member (nurse or MD). However, MEV dimensioning could be easily adapted, given its mechanical and monitoring modularity. Layout flexibility permits the best positioning of bed rows watching the individual monitors. The pressure and flow sensors on both the inspiratory and expiratory lines permit all the alarming options of common ventilators, the main of which would alert about tidal volume out of the set range.B.The oversizing of the main pipe section and dead-volume were imposed by the mechanical and ease-of-handling features. Nonetheless, they also permitted the favorable fluid-dynamic response shown in the results for the worst case of the farthest patient  when inspiration was started in synchrony with the 9 ones, upstream and with demanding tidal volume and respiratory rate (RR) settings. The theoretical lower bound of PIP drop (instantaneous adiabatic expansion) limited to –6.18% provided a general result, independent from cycle timing and pulmonary patients’ features. This permits to conclude that the asynchronous modes discussed in the next Par. and SM-A are feasible under general operative conditions.C.The main functional goal was to reach independently personalized controlled and assisted mechanical ventilation. This includes, single patient adaptation of the individually set tidal volume, PEEP, inspiration/expiration duty cycle, and single patient adaptation of RR.As to pressure-controlled, volume-guaranteed mode, the physician will be allowed to input on the bed touchscreen the aimed tidal volume. The system will slowly  adapt the inspiration/expiration duty cycle from the nominal value  within the admitted range (1:1–1:3), keeping alarm until the set tidal-volume is reached.Assisted-ventilation will be triggered by patient determined pressure/flow values. Briefly, i) a pressure drop in the inflow sensor will trigger the inspiration valve opening; ii) inflow equals to a predetermined percentage of the maximum peak of inflow or the reaching of a predetermined maximum inspiration time will trigger the switch to expiration. Alarm to be given if any of the above phase timed out or if the preset tidal volume and/or flow/min was not reached.The main feature of ventilation strategies imposed by a fixed PIP permits the sole adaptation of time settings, mainly the duty-cycle. This obviously limits the applicable pressure-volume cycles, compared to those settable in a full ventilator. However, this limit is in favor to maximum safety against barotrauma.2 and PIP common to all patients are foreseen to significantly constrain MEV application protocols. High FiO2 levels  can be considered in the first days of severe pneumonia treatment, starting with pressure-controlled, volume guaranteed mode and ending with assisted ventilation. However, the availability of ventilators would suggest moving recovering patients to standard treatment, as soon as possible. The same would be necessary for very severe patients to whom a fixed PIP could be not applicable. In case of extreme shortage, the only solution could be moving the recovering patients to a MEV delivering lower FiO2 levels . Technical solutions with personalized O2 mixtures could be easily conceived; however, the crisis contexts for which MEV is proposed suggest to attentively consider the tradeoffs between higher flexibility and instrumentation essentiality. In summary, the MEV backup is hopefully addressed to partial substitution of missing ventilators.Limits due to FiOV.The proposed MEV system was conceived at the highest peak of pandemic increasing rate in Northern Italy to overcome limits of adaptations of ICU ventilators to two or more patients and to provide a backup option to the lack of full ventilators, which are the first option. In this short presentation, the feasibility of the proposed system was shown, highlighting points of strengths relevant to robustness, intrinsic safety, and flexibility of each single patient ventilation mode. Intrinsic limits relevant to a common inspiration pressure and oxygen concentration can be foreseen as sufficiently compensated by the high gain in the equipment simplicity and sensibly lower costs.


In the whole group of 96 children, active renin concentration correlated positively with serum potassium and office and ambulatory systolic and diastolic blood pressures. Among children with hypertension, patients with isolated systolic hypertension had lower renin concentration than patients with systolic-diastolic hypertension . The active renin concentration did not differ between patients with isolated systolic hypertension and healthy children. In multivariate analysis, diastolic blood pressure Z-score  was the only predictor of active renin concentration in the studied children. We concluded that active renin concentration is positively associated with blood pressure and potassium in children, and diastolic blood pressure was the strongest predictor of renin level. Patients with isolated systolic hypertension may differ from patients with systolic-diastolic hypertension in less severe activation of the renin-angiotensin-aldosterone system.Our study aimed to assess active renin concentration in children with primary hypertension. Thus, we evaluated active renin concentration, clinical parameters, office and ambulatory blood pressure, and biochemical parameters in 51 untreated adolescents with primary hypertension (median: 14.4 [interquartile range—IQR: 13.8–16.8] years) and 45 healthy adolescents. Active renin concentration did not differ between patients with hypertension and healthy children (median: 28.5 [IQR: 21.9–45.2] vs. 24.9 [IQR: 16.8–34.3] [pg/mL],  Arterial hypertension stands among the most common chronic diseases affecting society. Its prevalence is estimated at 3–5% in pediatric individuals . PrimaryThe classic and probably the most studied pathophysiological pathway in hypertension, is the renin-angiotensin-aldosterone system (RAAS).Renin is an aspartyl protease with a molecular weight of 37 kDa, produced in many tissues and organs. Still, the primary source of plasma renin is the juxtaglomerular apparatus and the collecting tubule cells. Renin is produced as prorenin, an inactive precursor with 386 amino acids .The only known substrate of renin is angiotensinogen, from which the enzyme cleaves the 10-amino acid peptide angiotensin 1. In the classical RAAS axis, angiotensin one is converted by the angiotensin-converting enzyme (ACE) by removing two amino acids to angiotensin 2. Angiotensin II, a central player in the classical RAAS system, exerts biological actions by binding to its receptors . PhysiolIn clinical practice, the concentration of active renin or, requiring more restrictive sampling conditions, plasma renin activity, is most often determined. Single papers indicate that the measurement of active renin concentration is a specific marker of renin-angiotensin-aldosterone system activation, is more accurate at both low and high renin concentrations, and does not depend on angiotensinogen concentration ,8.Given the insufficient data in the pediatric population, our study aimed to evaluate the concentration of active renin in a population of untreated adolescents with primary hypertension and assess the relationship between active renin concentration, blood pressure, and selected clinical and biochemical parameters.p = 0.05, and an effect size of 0.55 should be 45 , body weight [kg] and body mass index (BMI), and were presented as Z-scores (SDS) .In all study participants, blood was collected after 2 h in an upright position in the morning (between 7 am and 10 am) after a 12-h fasting period according to our local protocol. All patients were evaluated in a euvolemic state on at least seven days of a normal sodium diet. Blood was allowed to clot, then promptly centrifuged under controlled conditions and frozen at −80 °C. Blood was thawed immediately before further analysis steps. The concentration of active renin [pg/mL] was determined by the ELISA (enzyme-linked immunosorbent assay) method  kit using a Biochrom Asys UVM 340 Scanning Microplate Reader .2], uric acid concentration [µmol/L], lipidogram: total, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol [mmol/L], and triglycerides [mmol/L], and serum sodium [mmol/L] and potassium [mmol/L]. In addition, we evaluated morning urinary albumin [g/L], sodium [mmol/L], potassium [mmol/L], and creatinine [mmol/L] with calculation of albumin-creatinine ratio [mg/g].Other parameters evaluated from peripheral blood included those assessed by standard local laboratory methods: morphology-based inflammatory parameters: neutrophil, lymphocyte, and platelet counts [1000/μL], mean platelet volume [fL], and calculated derivative indices: neutrophil-lymphocyte and platelet-lymphocyte ratio , serum creatinine concentration [µmol/L] used to calculate estimated glomerular filtration rate (eGFR)   and Z-scores both in the whole participants’ cohort and among patients with hypertension, but no such association. The relationship between blood pressure and renin in healthy individuals and hypertensive patients may differ. It may reflect the complex role of RAAS in the pathophysiology of primary hypertension. For example, no significant relation between components of RAAS and blood pressure was found in a Chinese cohort of pediatric patients with primary hypertension . On the Our results might suggest that renin-angiotensin-aldosterone system activation could be one of the driving forces of blood pressure elevation in the young. Of note, secondary forms of hypertension were excluded in all of our patients. Thus, there were no patients with typically renin-mediated hypertension  or low-renin hypertension .The significant difference in active renin concentration between untreated patients with isolated systolic hypertension and systolic-diastolic hypertension is a remarkable finding of this study. Isolated systolic hypertension has become a hot topic in pediatric and young adult hypertension in recent years. First, it is the predominant phenotype of hypertension in this age group. Second, increasing data indicate that these patients are significantly different from patients with systolic-diastolic hypertension. The isolated increase in systolic blood pressure in young individuals is not apparent. Postulated pathways include hyperkinetic circulation and high aortic elasticity leading to significant amplification of peripheral arterial pressure . And indTraditionally, activation of the renin-angiotensin-aldosterone system promotes renal tubular sodium reuptake and urinary potassium wasting. Both aldosterone and angiotensin II have their receptors on distal tubular cells influencing ion homeostasis . Thus, aKidney-independent activation of RAAS in adipose tissue has been proposed to link obesity and the risk of hypertension. Expression of virtually all components of RAAS has been demonstrated in adipocytes, and adipose-derived angiotensinogen is released into plasma, thus contributing to an increase in systemic blood pressure . ConversWe found no association between active renin concentration and BMI in our cohort. In the previously cited Shatat and Flynn cohort, plasma renin activity correlated positively with BMI . The difIt is essential to emphasize the limitations of this study. First, the study’s cross-sectional nature makes it impossible to infer causal relationships between renin and blood pressure levels. Second, we did not compare values of active renin concentration with the assay used in clinical practice—plasma renin activity or aldosterone levels—as most patients did not have this test done (the results were accessible only for eight hypertensive children)—in our center, they are not routinely performed in adolescents with stage I hypertension and the absence of end-organ damage. An important limitation of the study is the lack of data on urinary potassium excretion in most patients studied. In addition, we used local standards to analyze blood pressure, which may limit the relevance of our results to other pediatric populations. Finally, the study did not analyze end-organ damage or central blood pressure.Despite significant advances in knowledge regarding the pathogenesis of primary hypertension, the renin-angiotensin-aldosterone system remains at the heart of various pathophysiological concepts. Our results among children and adolescents with primary hypertension indicate that the concentration of active renin is positively associated with blood pressure elevation and serum potassium level. Interestingly, this study also revealed no increase in renin in patients with isolated systolic hypertension, and diastolic blood pressure was the only predictor of renin concentration in multivariate analysis. This finding might help to understand the differences between isolated systolic hypertension and systolic-diastolic hypertension in the young.


Traumatic Brain Injury (TBI) and stroke are major sources of death and disability worldwide. Acupuncture has been used as a supplemental therapy for patients with TBI and stroke. This study was aimed to evaluate the effects of acupuncture therapy for patients with TBI and stroke by radial pulse spectrum.22 patients (6 TBI and 16 stroke) were enrolled and underwent radial pressure wave measurement before and after acupuncture treatment at Dubi (ST-35), Zusanli (ST-36) and Jiexi (ST-41). The harmonic analysis of the radial pressure wave was calculated and transformed into Fourier series coefficients Cn, Pn and the variation coefficient CnCV.After acupuncture, systolic blood pressure, heart rate, and Glasgow Coma Scale changed very slightly. The harmonic index C4, C7, C9, C10, C3CV and C5CV had significant increases. (P < 0.05) After 3-week course acupuncture treatment, systolic blood pressure, C7, C8, C9, C10 and P10 had significant increases. (P < 0.05)Harmonic analysis of radial pulse waves may detect earlier circulatory system changes of acupuncture treatment before they were evident with other hemodynamic readings or scale.  •The pressure pulse spectrum of the radial pressure wave of patients with traumatic brain injury and ischemia stroke after acupuncture therapy may gradually change.•Harmonic analysis of the pressure pulse is a useful method to quantitatively study and quantify the efficacy of acupuncture treatment on traumatic brain injury and stroke patient.•Harmonic analysis may understand the underlying mechanisms of cardiovascular changes in patients with acupuncture treatment. TBITraumatic Brain InjuryCnThe nth harmonic proportionsCnCVThe variation coefficient of nth harmonic amplitudeGCSGlasgow Coma ScaleSBPSystolic blood pressureDBPDiastolic blood pressureHRHeart rate1,Traumatic Brain Injury (TBI) and stroke are major sources of death and disability worldwide. Complementary to conventional treatments such as surgery, medication, and rehabilitation, acupuncture is increasing a supplemental therapy for patients with TBI, ischemia stroke.The resonance theory provides a scientific explanation of the acupuncture effectAcupuncture research has been the focus of long-standing and persistent attacks by skeptics.22.1Patients with TBI and stroke were recruited from the Hualien Tzu Chi General Hospital in Taiwan from April to August in 2020. The cohort included 13 men (59%) and 9 women (41%), aged between 28 and 85. The study was conducted in accordance with the Helsinki Declaration and Good Clinical Practice Guidelines approved by the Hualien Tzu Chi General Hospital Institutional Review Board (IRB number: IRB108-200-B). Patients were hospitalized immediately after the injury (n = 6) or the stroke (n = 16) and on average received 3 weeks of treatment in the hospital.2.2The acupuncture treatments were at Dubi (ST-35), Zusanli (ST-36) and Jiexi (ST-41) according to the clinical experience of the specialist. As demonstrated in Radial pulse spectrum was non-invasively measured by a medical grade device . After completing the radial pulse wave measurement, blood pressures and heart rate were measured by an automatic blood pressure monitor  and GCS was evaluated by a physician.2.3The continuous pressure pulses were recorded for 12-s. The sampling rate of pressure data was 400 points per second. For example, with a heart rate of 100 beats per minute (1.67 Hz), the resolution of the sensor in the 10th phase is 0.262 radians. The pulse waveforms were transformed into the frequency domain. Heart beat is a repeated signal with period T, the pulse (P(t)) can be decomposed into harmonics as following:In this study, we focused on the change in the first ten harmonics and computed the harmonic proportions  instead of the amplitude . Cn was defined as Cn = An/A0, where A0 is the mean pulse pressure value. Pn was the nth phase of the harmonic. The variation coefficient of nth harmonic amplitude (CnCV) are defined in the supplementary , diastolic blood pressure (DBP), and heart rate (HR) are reported as mean ± standard deviation. Student's t-test was used for statistical comparisons. The level of statistical significance was set at P < 0.05.3Cn after (a) one acupuncture treatment and (b) a 3-week course of acupuncture treatment. This study provided a non-invasive measurement to evaluate the changes in the physiological and circulatory system of patients with TBI and stroke. Harmonic analysis of radial pulse wave has been found to characterize physiological meanings beyond blood pressure.The evidence provided from clinical and laboratory suggests that acupuncture induces multi-level regulation via complex mechanisms to explain the beneficial effects against cerebral ischemia and TBI.TBI and stroke are related diseases caused by cerebral ischemia from trauma or vascular obstruction. High-frequency harmonic indicators were found to be related to brain circulation. Changes in C6–C10 were observed after drinking tea to boost the brain circulation.CnCV represents the unstable state of the circulatory system, and changes in CnCV may also be used to evaluate the effect of treatment.After 3 weeks of acupuncture treatment, P10 increased significantly. Mathematically, the phase of the pulse spectrum represents the starting position of each harmonic. In our previous research, we found that the harmonic phase changes significantly when the organ is seriously injured.However, it is regrettable that real-time head blood flow information was not obtained for reference in this study. In future work, through real brain blood flow measurements such as laser Doppler, ultrasound, fMRI and nuclear imaging, it will be possible to clarify the effect of acupuncture on brain circulation in TBI and stroke patients and the relationship between each harmonic index and head circulation. In addition, although there was no immediate significant difference in GCS in this study, the hemodynamic mechanisms of the three GCS assessments-eye opening, verbal response, and motor response-could be investigated separately through harmonic analysis after accumulating enough patient data.4Harmonic analysis studies of the changes in the pulse wave in response to the acupuncture treatment using the self-comparison method. These findings confirm that harmonic analysis of the pressure pulse is a useful method to quantitatively study and quantify the efficacy of acupuncture treatment on TBI and stroke patient.10.13039/501100015640TJH, JKC, SHW. Funding acquisition: TJH, JKC.Conceptualization: TJH, HPC, TCW. Methodology: SHW, JKC. Software: SHW, GCW. Validation: TCW, TJH. Formal analysis: SHW, GCW, TCW. Investigation: JKC, WTT, SZL,TJH. Resources: JKC, SZL, TJH. Data curation: JKC, SHW. Writing – Original Draft: JKC, SHW. Writing – Review & Editing: TCW, TJH, HPC. Visualization: SHW. Supervision: TJH. Project administration: 10.13039/501100022298Hualien Tzu Chi Hospital (TCRD109-35)This research was supported by This research was reviewed and approved by the institutional review board of Hualien Tzu Chi Hospital (registration number IRB108-200-B). Informed consent was obtained from all participants.The data are not publicly available due to confidentiality under Taiwan law.The authors declare that they have no conflicts of interest.


Belatacept (Bela) was developed to reduce nephrotoxicity and cardiovascular risk that are associated with the chronic use of Calcineurin inhibitors (CNIs) in kidney transplant recipients. The use of Bela with early steroid withdrawal (ESW) and simultaneous CNI avoidance has not been formally evaluated.At 3 months post-transplant, stable kidney transplant recipients with ESW on Tacrolimus (Tac) + mycophenolate (MPA) were randomized 1:1:1 to: 1) Bela+MPA, 2) Bela+low-dose Tac , or 3) continue Tac+MPA. All patients underwent surveillance graft biopsies at enrollment and then at 12, and 24 months post-transplant. Twenty-seven recipients were included; 9 underwent conversion to Bela+MPA, 8 to Bela+low-dose Tac and 10 continued Tac+MPA. Serial blood samples were collected for immune phenotyping and gene expression analyses.2 increase in eGFR compared to -0.38 mL/min/1.73 m2 in Tac+MPA, P= 0.243. One graft loss occurred in the Bela+MPA group. Immunophenotyping of peripheral blood monocyte count (PBMC) showed that CD28+CD4+ and CD28+CD8+ T cells were higher in Bela+MPA patients with acute rejection compared to patients without rejection, although the difference did not reach statistical significance.The Bela+MPA arm was closed early due to high rate of biopsy proven acute rejection (BPAR). The incidence of BPAR was 4/9 in Bela+MPA, 0/8 in Bela+low dose Tac and 2/10 in Tac+MPA, P= 0.087. The Bela+low-dose Tac regimen was associated with +8.8 mL/min/1.73 mOur data indicate that, in steroid free regimens, low-dose Tac maintenance is needed to prevent rejection when patients are converted to Bela, at least when the maneuver is done early after transplant. Since the development of calcineurin inhibitors (CNIs) in the 1980s, the rate of early acute rejection in kidney transplant recipients has dramatically declined leading to excellent short-term outcomes, but long-term graft survival has increased only slightly , 3. FurtBelatacept (Bela) was developed to improve long-term outcomes in kidney transplant patients by avoiding the toxic effects of CNIs. It is a human fusion protein composed of an Fc fragment of IgG1 immunoglobulin linked to the extracellular domain of CTLA-4, which blocks the CD80/CD86 costimulation signals during the interaction between antigen presenting cells and T cells, preventing their activation. It was shown to be noninferior to CNIs and associated with improved renal functions in a phase II study in adult kidney transplant recipients . The U.SIn all the above studies –12, patide novo studies demonstrated the nephroprotective effects of Bela in kidney transplant recipients, this was associated with increased rates of rejection within the first year post-transplant. Therefore, we aimed to assess the impact of early conversion from tacrolimus to Bela for maintenance immunosuppressive therapy at 3 months post-transplant in adult kidney transplant recipients. We used induction treatment with the lymphocyte depleting agent Alemtuzumab (anti-CD52 antibody) and a steroid free maintenance protocol. We evaluated the effect of this protocol on patient and allograft survival, incidence of rejection and renal graft function. Additionally, the study endpoints included the incidence of adverse events such as new-onset post-transplant diabetes mellitus, hyperlipidemia, infections, and malignancies. The study was designed as a prospective randomized trial with a 24-month follow-up duration.While both the BENEFIT and BENEFIT-EXT In this open-label (not blinded), single center, randomized study , kidney allograft recipients received maintenance immunosuppression with tacrolimus (Tac) and mycophenolate (MPA) for the first 3 months post-transplantation and then they were randomized 1:1:1 to undergo conversion to Bela with MPA, Bela with low dose Tac or continue on Tac with MPA. The Institutional Review Board (IRB) of Northwestern University, Chicago, IL, approved the study.Male and female kidney transplant recipients from living or deceased donors, older than 18 years, EBV seropositive were assessed for eligibility. All subjects needed to demonstrate ability to provide consent and comply with the study procedures. Patients were consented and randomized at 3 months post-transplant.EBV negative or unknown recipients and those with history of acute rejection within 3 months prior to randomization were excluded from the study. Other exclusion criteria included: pre-transplant donor-specific antibodies, presence of proteinuria >1 g/day or > 0.5 g/day if diabetic in two weeks prior to randomization, rejection on 3-month posttransplant screening biopsy, BK nephropathy on 3-month screening biopsy, positive pregnancy test at the time of randomization, history of previous transplant, history of human immunodeficiency virus (HIV), history of hepatitis C virus, end stage kidney disease (ESKD) secondary to primary focal segmental glomerulosclerosis (FSGS) and participation in an investigational drug or medical device study within 30 days or five drug half-lives, whichever was longer, prior to enrollment into this study.3). At 3 months post-transplantation, eligible patients who consented to participate in the study were randomized in a 1:1:1 ratio, using a computer-generated list and block randomization, to be converted to Bela with MPA, Bela with low dose Tac or continue with Tac with MPA. Tac was administered to target 12-hour trough level of 8-10 ng/mL during the first 3 months, 7-9 ng/mL from 4-6 months post transplantation and 6-8 ng/mL thereafter. The dose was modified for the second group (Bela with low dose Tac) to maintain a trough level of ≤ 5 ng/mL. Blood Tac trough levels were measured by LC-MS/MS method.All patients received induction with alemtuzumab as a single dose of 30 mg IV over 2 hours intraoperatively and methylprednisolone at 500 mg IV followed with rapid steroid elimination (Methylprednisolone 250 mg post-transplant day 1 and 125 mg post-transplant day 2). All patients were maintained on steroid free regimen with Tac and MPA. MPA was started at the dose of 1000 mg twice/day and adjusted as indicated for leukopenia (WBC<2000/mmde novo donor specific antibodies (DSA), and incidence of adverse events such as infections, malignancies, posttransplant diabetes mellitus and hyperlipidemia.The primary endpoint of the study was the change in the estimated GFR (eGFR), using MDRD equation, at 2 years posttransplant from the baseline at the time of conversion. The secondary endpoints included patient and renal allograft survival, incidence of biopsy proven acute rejection (BPAR), incidence of Data collected included immunosuppressive regimen used, recipient demographics such as age, gender, race, case of end-stage kidney disease, history of diabetes mellitus, hypertension, congestive heart failure, need for dialysis prior to transplant, panel reactive antibody level %, degree of HLA mismatch and donor characteristics (living vs. deceased). Posttransplant data included incidence of delayed graft function (DGF), rate of acute rejection, eGFR, patient survival, graft survival, DSA levels, incidence of diabetes, hyperlipidemia  post-conversion, infections, malignancies and proteinuria.To evaluate the impact of this immunosuppressive maintenance regimen on allograft histopathology, we obtained surveillance biopsies at baseline (time of conversion at 3 months post-transplantation), 12 months and 24 months post-transplantation.We isolated peripheral blood mononuclear cells (PBMC) from peripheral blood by Ficoll gradient and we stored them in liquid nitrogen for batched analysis. For multicolor flow cytometry analyses, we used the following monoclonal antibodies: from Becton Dickinson , CD3-FITC, CD3-PerCP-Cy5.5, CD4-APC-Cy7, CD8-BV510, CD45RO-FITC, CD45RA-APC, CD45RA-APC-Cy7, CD71-PE, IgD-PerCP-Cy5.5, CD25-APC-Cy7, CD138-BV421, CCR4-PE, CD27-PE, CD95-BV421, CD28-BV421, TIM3-BV421, CCR6-BV421, CCR7-AF700, CXCR3-PE, IL-2-PE, IL-17-BV786, and IFN-γ-PE-Cy7; from Biolegend , CD19-BV510, CD56-FITC, CD27-APC, CD127-FITC, CD57-PerCp-Cy5.5, PD-1-APC-Cy7, CXCR5-FITC, LAG3-APC, IL-10-PerCP-Cy5.5, and TNF-α-FITC. From eBioscience , CD4-PE-Cy7, CD21-PE, and CD24-APC-Cy7 were used. From Miltenyi Biotec , CD25-APC and anti-KLRG1-PE were used. From Beckman Coulter , CD38-PE-Cy7 was used.+, CD8+, and CD19+. Cells were fixed and permeabilized using Intracellular Fixation and Permeabilization Buffer Set (eBioscience) according to the manufacturer’s instructions.We performed intracellular staining for IL-2, IL-4, IL-17, IFN-g, and TNF-a together with extracellular markers for CD46 events) on a 3-laser FACSLyric flow cytometer (BD Biosciences) and analyzed with FlowJo® software.Data were acquired  laboratory  to generate Tuteva risk score results in order to assess the performance of the Verici Dx Tuteva test for the prediction of clinical and subclinical acute rejection (AR).The baseline data were summarized using descriptive statistics . ANOVA test or Wilcoxon rank sum test was used to compare continuous variables. Chi-square or Fisher exact tests was used to compare categorical variables. Patient survival, graft survival, and occurrence of rejections were estimated using Kaplan-Meier survival estimates, where the cumulative estimates of the three groups were compared using the Log-rank test. A mixed-effect model was used to compare the eGFR slopes over time between the three groups.® version 9.3.1 software package  at serial time points.Flow cytometry results were presented as mean and standard error of the mean. Comparisons of continuous variables between groups was performed by unpaired t-test. Comparisons across serial time-points within the same group was done by ANOVA. P < 0.05 was considered as statistically significant. Statistical analysis was performed using GraphpadPrismPatients were recruited from February 2015 to September 2018. Three hundred and ninety-five patients were screened for eligibility to participate in the study. Twenty-eight patients who met the enrollment criteria consented and were randomized. 2  in the Tac+MPA group compared to +8.8 ml/min/1.73 m2 ; P= 0.243, in the Bela+low dose Tac group, and -6.60 ml/min/1.73 m2 ; P= 497, in the Bela+MPA group  .Two patients developed There was no significant difference between the three groups in terms of rates of infection, BK viremia, CMV viremia, malignancy, leukopenia, hyperlipidemia and diabetes Table 2.We analyzed the histopathological data of patients who completed 24-month follow up period. There was no significant difference in interstitial fibrosis/tubular atrophy, glomerulosclerosis, arteriosclerosis, arteriolar hyalinosis and transplant glomerulopathy between the three groups at 3-, 12-, or, 24-month surveillance biopsies.–We performed extensive immune phenotyping of PBMC collected from all the participants at 3 months (time of randomization), and at 6, 12, and 24 months posttransplant. At 3 months, none of the T cell subsets  were fully recovered after alemtuzumab depleting induction, but they did not significantly change across the three treatment groups during the follow-up period –3. Tren+ T cells have been associated with an increased risk of acute rejection in patients on Bela, but not on Tac, suggesting that these cells are resistant to Bela and may be implicated in the acute rejection episodes occurring after conversion from Tac  that is performed centrally in the Verici Dx laboratory in accordance with CLIA regulations. The Tuteva test AR risk score results of 21 participants demonstrated a negative predictive value of 91.67% , a positive predictive value of 70% , a sensitivity of 87.50% , a specificity of 78.57% , an accuracy of 81.82% , and an area under the receiver operating characteristic curve of 0.83 for predicting biopsy proven borderline rejection or acute renal allograft rejection. The prevalence of borderline changes/acute rejection in this group of participants was 36.36%.de novo DSA formation despite an early increase in acute rejections.Calcineurin inhibitor avoidance in kidney transplantation is challenging and has been associated with high rejection risk. Since its approval in 2011, Bela has allowed CNIA and resulted in reduced nephrotoxicity and 2 increase in the eGFR at 24 months post-transplantation. There were no early acute rejections, renal graft loss or development of de novo DSA in patients randomized to that treatment arm. Our findings confirm and expand the findings form the BENEFIT and BENEFIT-EXT trials. In contrast to those two studies, our study used 1) the lymphocyte depleting agent Alemtuzumab for induction along with early steroid withdrawal; 2) Tac, rather than CSA, which was used in BENEFIT and BENEFIT-EXT; and 3) our study included patients with high PRA, which were excluded in those trials.Our study of steroid-free kidney transplant recipients indicates that early conversion from Tac to Bela in combination with MPA is associated with a high rate of early acute cellular rejection (4/9), which led to early closure to enrollment to that arm of the study. On the other hand, our data showed that conversion to Bela + low-dose Tac  is an effective steroid-free maintenance immunosuppressive regimen and was associated with a +8.81 ml per minute per 1.73 mIn the Bela+MPA group there was one renal allograft loss, which was associated with early Banff 2A acute cellular rejection. Despite early treatment with anti-thymocyte globulin, steroids, and conversion to Tac+MPA, the allograft function did not recover, and the patient was initiated on hemodialysis 20 months post transplantation. The high rate of rejections probably impacted also the eGFR that was numerically lower in the Bela+MPA group at the end of the study.+ T cells in the circulation. This is consistent with the hypothesis that CD28+ effector memory T cells, capable of producing high levels of IL-2, are a biomarker for rejection risk in Bela patients  and a fair positive predictive value (70%) for predicting biopsy proven borderline changes/acute rejection. Further study of this newly available test in a larger cohort of patients is needed.Belatacept was well tolerated by our cohort, and there were no significant differences across the three groups in the incidence rates of infection, malignancy, neutropenia, hyperlipidemia, or diabetes, further supporting the safety of Bela regimens that include T-cell depletion induction therapy. There were no PTLD cases in our study of EBV seropositive patients, supporting the concept that PTLD does not represent a safety concern in EBV seropositive patients.There are a few caveats to consider when interpreting our study findings. First, the small sample size limited the power of our study and generalizability of our findings. The relatively short follow-up also reduced our chances to detect as statistically significant the different trends in eGFR across treatment arms, although serial surveillance graft biopsies did not reveal major differences. Due to the limited availability of Alemtuzumab in many countries, generalizability of our findings might be limited.In conclusion, our study evaluated the impact of early conversion of CNIs at 3 months to Bela in a steroid-free maintenance immunosuppressive therapy following induction with Alemtuzumab. Our findings indicate that early conversion to Bela helps reduce the required maintenance dose of CNI to a lower level that potentially improves renal allograft function without the development of early rejections. The findings also suggest that early conversion to Bela in combination with mycophenolate without steroids is associated with a high rate of early rejection and potentially lower renal allograft function or even allograft loss. Further evaluation of a Bela-based maintenance regimen in a larger cohort of kidney transplant recipients using a steroid-free regimen is needed to support these findings.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by the Institutional Review Board (IRB) of Northwestern University, Chicago, IL. The patients/participants provided their written informed consent to participate in this study.IT participated in the research design, data analysis and writing the paper. PH, FY, MS-B and AI participated in the writing of the paper. JL and MA participated in the performance of the research. PC and SB participated by immune phenotyping and proofreading the manuscript draft. LG was the principal investigator and the supervisor for this study. All authors contributed to the article and approved the submitted version.


Median ICG ingress at the proximal ureteral third was 14.00 (5.00–33.00) AU in patients with and 23.50 (4.00–117.00) AU in patients without complications . The proposed definition and grading of post-transplant ureterovesical anastomosis complications is intended to enable valid comparisons between studies. ICG Fluorescence angiography allows intraoperative quantitative assessment of ureteral microperfusion during kidney transplantation and is able to predict the incidence of ureterovesical anastomosis complications. Registration number: NCT-02775838.Ureteral stenosis and urinary leakage are relevant problems after kidney transplantation. A standardized definition of ureterovesical anastomosis complications after kidney transplantation has not yet been established. This study was designed to demonstrate the predictive power of quantitative indocyanine green (ICG) fluorescence angiography. This bicentric historic cohort study, conducted between November 2015 and December 2019, included 196 kidney transplantations. The associations between quantitative perfusion parameters of near-infrared fluorescence angiography with ICG and the occurrence of different grades of ureterovesical anastomosis complications in the context of donor, recipient, periprocedural, and postoperative characteristics were evaluated. Post-transplant ureterovesical anastomosis complications occurred in 18%. Complications were defined and graded into three categories. They were associated with the time on dialysis ( Most of the surgical transplant procedures are highly standardized and therefore comparable between different transplant centers, leading to relatively constant complication rates [Kidney transplantation has become the gold standard for the treatment of end-stage renal disease  and “Lich-Gregoir” (LG) . TaguchiAnother issue that can lead to complications of the ureteroneocystostomy is malperfusion of the ureter during the organ procurement. However, up to date no standardized method for the visualization of ureter perfusion during the transplant procedure has been implemented.Near-infrared fluorescence angiography with indocyanine green (ICG) is an emerging tool for intraoperative perfusion control after kidney transplantation. It has been demonstrated that delayed graft function after kidney transplantation can be predicted intraoperatively by applying this technique . A recenThe aim of this study was to identify risk factors for post-transplant ureterovesical anastomosis complications retrospectively on the basis of a new clinical definition of this complication, and to reevaluate the concept of ureteral malperfusion as a risk factor using the intraoperative findings of ICG fluorescence angiography for the assessment of the graft ureteral microperfusion.A bicentric historic cohort study was conducted including patients who had presented with end-stage renal disease and had underwent kidney transplantation. Deceased-donor and living-donor transplantations were included. All patients listed for kidney transplantation at two university hospitals between November 2015 and December 2019 were screened for study inclusion. In the absence of exclusion criteria, namely known allergy to iodine, ICG, contrast agents, severe hepatic dysfunction, pregnancy, hyperthyroidism, pulmonary hypertension, or allergic diathesis, patients were prospectively enrolled in the study (NCT-02775838) and the kidney allograft and transplant ureter perfusion analysis was conducted intraoperatively, as described below.A total number of 196 fluorescence videos were suitable for study inclusion into this study . The study was conducted in congruence with the Declaration of Helsinki and the Declaration of Istanbul and was approved by the ethics committees of the universities of Erlangen-Nuremberg and Mannheim ; all patients gave their written informed consent. The study adhered to the STARD guidelines [The standard techniques were used for preoperative diagnostics, organ procurement, and the transplantation procedure. The operative procedures were exclusively performed by surgeons with several years of experience in kidney transplantation. A transurethral catheter was placed into the bladder under sterile conditions. During bench dissection special care was taken to preserve the periureteral fat and blood vessels.Intraoperative ICG fluorescence angiography of the allograft was performed with the SPY Elite system  five minutes after reperfusion. A single bolus of ICG  was administered intravenously at a standardized dose of 0.02 mg/kg body weight . The assThe fluorescence angiography videos in a gray scale of 256 different shades were analyzed postoperatively regarding the change of fluorescence intensity over the time using the integrated SPY-Q analysis tool-kit . Four parameters of microperfusion are defined in the quantitative analysis by the SPY-Q software: “Ingress”, “Ingress Rate”, “Egress”, and “Egress Rate”. The analysis regarding cortical microperfusion of the kidney allograft and quantification has been described in prior studies ,16. QuanThe periprocedural transplant as well as patients characteristics were assessed. The ureter function was monitored up to one year after kidney transplantation. Therefore, all ureter revision procedures after allograft transplantation were recorded. According to clinical considerations, the type of ureteral complication was graded into three different categories (Grade A–C) as shown in Assuming a complication rate of about 20%, a power analysis provided that the sample size of 196 patients is sufficient to detect a medium effect regarding a quantitative variable with a power of 0.90.All statistical calculations were performed using SAS statistical software, release 9.4 . Quantitative variables are presented as mean values together with standard deviations or  as median values together with minimum and maximum. For qualitative factors, absolute and relative frequencies (percentages) are given. The comparison of two independent groups  was performed using the Fisher’s exact test for qualitative factors, the Cochran–Armitage trend test for ordinally scaled parameters, or the Mann–Whitney U test for quantitative variables, respectively. In order to compare more than two groups, the Kruskal–Wallis test was applied. For the comparison of the ureter thirds regarding ingress or ingress rate, the Friedman test was performed supplemented by Wilcoxon tests for two paired samples in case of a significant test result.In order to investigate the correlation between two quantitative variables of perfusion assessment, the Spearman correlation coefficient was assessed.Furthermore, logistic regression analyses were performed to identify parameters potentially associated with ureterovesical anastomosis complications. For each regression model, the AUC (area under the ROC curve) was calculated as a measure of goodness.p < 0.05 was considered to show a statistically significant test result.In general, In total, 196 patients were included in this historic cohort study (141 deceased-donor and 55 living-donor kidney transplantations). Mean recipient age was 54 (±14) years. The study included 132 male (67%) and 64 female (33%) patients. The median time on dialysis was 40 (0–171) months.Regarding vascularization, 142 kidney grafts were transplanted with a single-artery supply, 45 grafts had 2 and 4 grafts had 3 arteries. In 17 grafts there was a separate upper pole and in 12 grafts there was a separate lower pole artery. The majority of organs was drained by a single vein. Eight organs had two and one organ had three veins. All of the kidneys had a single ureter. The median operating time was 172 (64–433) minutes. The median cold ischemia time was 566 (0–1680) minutes and the median warm ischemia time was 28 (12–121) minutes.Post-transplant ureterovesical anastomosis complications occurred in 36 patients (18%). Most of the patients with ureterovesical anastomosis complications were classified as grade A , i.e., they could be treated conservatively by prolonged retrograde ureteric stenting. A complication grade B, that required nonsurgical antegrade endourologic intervention, occurred in 2 patients (6%) and a complication grade C requiring invasive surgical treatment developed in 12 patients (33%).p = 0.0025), the type of donation (p = 0.0404), and the number of postoperative dialysis sessions (p = 0.0173). The length of cold ischemia time was not significantly associated with the occurrence of overall complications (p = 0.0991).The subgroups of patients with any grade of ureterovesical anastomosis complication (grade A–C) and without complications (grade 0) are compared in p < 0.0001). Pairwise comparison between the thirds also yielded significant differences .A representative example of quantitative intraoperative ureteral microperfusion during kidney transplantation is presented in Median ICG ingress of the renal allografts was 156.00 (8.00–253.00) AU, ingress rate was 28.90 (0.10–78.90) AU. Regarding the two poles of the kidney, ingress at the upper pole was 130 (5.00–254.00) AU, at the lower pole was 125.00 (2.00–254.00) AU. Ingress rate at the upper pole was 23.10 (0–89.00) AU, and at the lower pole it was 21.00 (0–81.10) AU.p < 0.0001).ICG ingress and ingress rate at the proximal ureter correlated significantly positive with the equivalent perfusion parameters of the whole kidney and the three different parts of the kidney . NotablyBoth parameters of ureteral and kidney perfusion assessment characterizing inflow  showed significant differences between the subgroup of patients with any grade of ureterovesical anastomosis complication (grade A–C) and without complications (grade 0), as presented in The outflow parameters  generally show larger ranges and they did not always differ significantly between both groups, particularly regarding the middle and distal parts of the ureter. An example of a pattern of reduced intraoperative ureteral microperfusion in a patient with postoperative complications is shown in p = 0.8387) as well as ingress rate (p = 0.7035).The median ingress at the proximal ureter in Grade A ureterovesical anastomosis complications was 14.00 (5.00–25.00) AU. In Grade B it was 21.50 (10.00–33.00) AU and in grade C it was 14.00 (9.00–29.00) AU. There was no significant difference between the groups regarding ingress (p = 0.0243), but not for ingress rate (2.00 (0.20–4.50) vs. 3.05 (0.10–23.80), p = 0.0945). At the middle and distal third of the ureter, there was no significant difference for ingress or for ingress rate.Comparing the perfusion at the proximal ureter in grade C ureterovesical anastomosis complications with the remaining patients , a significant difference was detected for median ingress (14 (9.00–29.00) AU vs. 22 (4.00–117.00) AU, p = 0.0016), operation time (p = 0.0144), URp ingress (p = 0.0243), cold ischemia time (p = 0.0409), URp ingress rate (p = 0.0945), URp egress (p = 0.0939), URm ingress (p = 0.0763), and URd ingress (p = 0.0628).Univariable logistic regression analysis revealed an association of the following parameters with grade C post-transplant ureterovesical anastomosis complications: months on dialysis (p = 0.0256) for the prediction of grade C complications.Multiple logistic regression analysis  revealed only cold ischemia time being significantly associated with grade C complications. The ROC analysis of the parameter “cold ischemia time” yielded an optimum cutoff value of 792 min, with a sensitivity of 67% and a specificity of 77% , the surgical technique for ureteral implant (only the LG method was applied), and the influence of the preoperative bladder volume capacity (not assessed consistently). Further studies are recommended to provide prospective validation of the definition and assess the influence of all potential risk factors. The ROC analysis performed here showed a good AUC and significant The proposed standardized definition of post-transplant ureterovesical anastomosis complications should unify the reporting of this complication while enabling comparison with the results from different studies. Moreover, this study demonstrates that ICG fluorescence angiography can safely be applied for objective intraoperative documentation of the quality of ureteral microperfusion during kidney transplantation. This is the first study providing threshold values for ICG ingress at the proximal ureteral third and the lower pole of the kidney for predicting ureterovesical anastomosis complications. These findings can be used for intraoperative quality control, for decision-making, and for individual postoperative risk stratification potentially improving the postoperative management of patients after kidney transplantation.


The secondary aim was to determine whether CBF and CDO2 were associated with clinical outcome.The primary aim was to determine to what extent continuously monitored neurointensive care unit (neuro-ICU) targets predict cerebral blood flow (CBF) and delivery of oxygen , pressure reactivity index, cerebral perfusion pressure (CPP), optimal CPP, and body temperature were assessed in association with the Xe-CT. The acute phase was divided into early phase (day 1–3) and vasospasm phase (day 4–14).In this observational study, patients with aneurysmal subarachnoid hemorrhage treated at the neuro-ICU in Uppsala, Sweden, from 2012 to 2020 with at least one xenon-enhanced computed tomography (Xe-CT) obtained within the first 14 days post ictus were included. CBF was measured with the Xe-CT and CDO2 for medians of 15% and 30%, respectively, of the cortical brain areas in each patient. In multiple regressions, higher body temperature was associated with higher CBF and CDO2 in the early phase. In a similar regression for the vasospasm phase, younger age and longer pulse transit time  correlated with higher CBF and CDO2, whereas lower hematocrit only correlated with higher CBF but not with CDO2. ICP, CPP, and pressure reactivity index exhibited no independent association with CBF and CDO2. R2 of these regressions were below 0.3. Lower CBF and CDO2 in the early phase correlated with poor outcome, but this only held true for CDO2 in multiple regressions.Of 148 patients, 27 had underwent a Xe-CT only in the early phase, 74 only in the vasospasm phase, and 47 patients in both phases. The patients exhibited cerebral hypoperfusion and poor CDO2. Still, cerebral hypoperfusion and low CDO2 were common and low CDO2 was associated with poor outcome. Xe-CT imaging could be useful to help detect secondary brain injury not evident by high ICP and low CPP.Systemic and cerebral physiological variables exhibited a modest association with CBF and CDOThe online version contains supplementary material available at 10.1007/s12028-022-01496-1. Neuro-ICU management is based on monitoring and optimizing CBF and CDO2 surrogates. Specifically, mean arterial blood pressure (MAP) and intracranial pressure (ICP) together constitute the cerebral perfusion pressure (CPP) (CPP = MAP − ICP)  2–4) and median Fisher grade was 4 (IQR 3–4). The aneurysm was located in the anterior circulation in 125 (84%) cases and in the posterior circulation in 23 (16%) cases. One hundred twenty-two (82%) patients were treated for their aneurysm with endovascular embolization, 23 (16%) with clipping, 1 with both embolization and clipping, and 2 received no treatment. Fifty-two (35%) patients developed DIND and received HHH-therapy. Ten (7%) patients required thiopental, and 15 (10%) decompressive craniectomy due to high ICP. After 1 year, median GOS-E was 3 (IQR 3–5), 36 (26%) had a favorable recovery, and 23 (16%) were deceased.2 was around 5 mL O2/100 g/min, and the percent of poor and severe CDO2 were 30% and 3%, respectively.The clinical and physiological data during the Xe-CT in the early phase and the vasospasm phase are described in Table 2 and a lower body temperature. A higher percent of critical hypoperfusion was associated with higher PRx. A lower CDO2 was associated with older age, lower body temperature, and lower pCO2. A higher percent of brain areas with poor CDO2 was also associated with older age and lower body temperature, whereas a higher burden of severe CDO2 only correlated with lower body temperature.In the early phase .A significant association between the CBF indices and CDO2 in the early phase was independently associated with favorable outcome after adjustment for age and WFNS grade , similar, but slightly weaker associations were found for CPPopt/PRx and CBF and CDO2. Third, the study group was highly selected to be patients in a bad clinical situation, who were intubated and with specific requirements on the monitoring for inclusion in the study. This, together with the limited number of individuals could explain why some tests did not reach statistical significance. Fourth, reduced CBF may be explained a reduction in energy metabolic demand by, e.g., concurrent brain injury, hypothermia and sedation rather than ischemia. However, the burden of hypoperfusion and critical hypoperfusion was calculated as the percent of cortical brain areas with CBF < 20 mL/100 g/min and CBF < 10 mL/100 g/min, respectively. These measures rather reflect the proportion of focal hypoperfusion rather than global changes related to sedation, etc. Fifth, including the patients treated with DIND may have influenced the overall results but excluding the patients with DIND from the univariate correlation analyses did not affect the associations. Sixth, DIND was diagnosed based on clinical ground by experienced clinicians, although it was possible that false positives and negatives (silent brain infarctions) occurred to some extent. Seventh, ABP was measured at heart level which overestimates CPP to some extent when the head of the bed is elevated but this did not affect the calculation of ∆CPPopt because it is the difference between CPP and CPPopt. The results may have been confounded by that a smaller group of patients receiving HHH therapy was placed in supine position but the results did not change when those patients were excluded from the analysis.First, the associations between systemic and cerebral physiological variables and CBF and CDOOlder patients with increased SVR were at increased risk of low CBF and oxygen delivery. A lower hematocrit correlated with higher CBF but not with increased oxygen delivery, which suggests a limited beneficial cerebral effect from hemodilution. Higher body temperature was associated with increased CBF and oxygen delivery but was more likely a consequence of increased energy metabolic demand. ICP, CPP, and pressure reactivity only had modest associations with CBF and oxygen delivery. Cerebral hypoperfusion and poor oxygen delivery were still common, which indicates that common neurointensive care variables were poor surrogates of these targets, and this corroborates the indication for multimodality monitoring, including CBF imaging, to better detect the development of secondary brain injury.Supplementary file1 (DOCX 71 kb)Supplementary file2 (DOCX 331 kb)Supplementary file3 (DOCX 252 kb)Supplementary file4 (DOCX 337 kb)Supplementary file5 (DOCX 262 kb)Supplementary file6 (DOCX 12 kb)Below is the link to the electronic supplementary material.


Glomerular filtration rate (GFR) measurement is a key tool for determining the degree of chronic kidney disease. The assessment of GFR is even more challenging in children than in adults with more variables in the equation than race and sex. Monitoring the progress of the kidney disease can therefore be difficult as in the initial stages of a decline in kidney function, there are no clinical signs. Due to children’s growth and development, changes in muscle mass and growth impair GFR estimation based solely on serum creatinine values. More invasive methods of GFR measurement are more reliable, but techniques using ionising agents, requiring large volume blood samples or timed voiding, have limited application in children. This paper reviews the methods of measuring and determining glomerular filtration rate and kidney function in children. Chronic kidney disease (CKD) is a growing problem in adults, but it is also important in children, although it occurs significantly less often. Research estimates the prevalence to be 74.7 cases per million children . Childre2 [In children under two years of age, adult CKD rates are not used, as normal GFR values are lower than 60 mL/min/1.73 mIn the present article, an overview of the possible methods of GFR measurement for children and useful techniques in clinical practice are presented. In addition, the problems regarding this basic method in children are emphasised.GFR is currently the best estimate of kidney function. It reflects the excretory function of the kidneys, which is the sum of the GFR of all nephrons. GFR may decrease due to reduced blood flow or fewer functioning nephrons. With single or multiple determinations, the degree of kidney damage is determined; it is defined as acute or chronic, and the rate of progression of the kidney disease is determined .GFR is influenced by the ultrafiltration pressure in the glomerular capillaries, capillary permeability and capillary surface area. Changes in any of these also result in a change in GFR .The total GFR consists of the GFR of all individual nephrons. The reduced rate of the GFR in all nephrons at the same time is the result of a decrease in blood flow through the kidneys when the effective circulating volume is reduced . The cause can also be a disturbance in the outflow of urine due to a bilateral blockage of the flow of urine, e.g., in congenital urinary tract defects such as posterior urethral valves. In intrinsic kidney disease, the cause of the decrease in GFR is the deterioration of nephrons. When individual nephrons are damaged, initially the GFR and tubular resorption in the remaining healthy nephrons increase, so the overall decrease in the GFR is not proportional to the loss of kidney tissue, and the GFR may initially be normal despite kidney damage. As nephrons continue to deteriorate, the GFR also decreases. Because the kidneys have a large functional reserve, clinical signs and symptoms of uraemia appear only when the GFR is reduced to 5–10 mL/min .Clearance is divided into kidney clearance and plasma clearance. The first is based on the measurement and calculation of the amount of filtered substance through the kidneys, which is why a constant concentration in the blood is required and, thus, more measurements from the urine. Plasma clearance is based on a single entry of a substance into the plasma and measurement of the concentration after a certain time, with which the elimination curve is measured and the excretion through the kidneys is calculated .The most common method for measuring GFR relies on the concept of renal clearance . In a he the GFR .In plasma clearance, a known amount (M) of an exogenous substance is injected intravenously, and by measuring the concentration in the blood after a certain period of time, the amount of the substance that has been excreted is calculated. GFR is defined as the ratio between the rate of secretion of a substance and the concentration of secretion in time (t): After a certain time, all the injected substance is excreted, so the amount of substance is equal to the area under the curve on the graph showing the concentration in the blood over time . The low2 of the body surface. Calculation of GFR shows that children reach the GFR of adults at 6–24 months of age [The normal value of GFR in adults is about 125 mL/min . To comps of age .In adults, the BSA value is calculated according to the Du Bois formula :BSA(m2)=BSA in children and adolescents can be calculated according to the equation of Haycock et al. :BSA(m2)=In paediatric clinical practice, the Mosteller formula is most often used :BSA(m2)=51chromium-ethylenediaminetetraacetic acid (51Cr-EDTA), 125iodine-iotalatamate, 99Tc-diethylenetriaminoacetic acid (99mTc-DMSA) or non-radioactive inulin and iohexol [If non-glomerular excretion is negligible for the substance used, the clearance of the substance is equal to GFR. We can measure clearances of endogenous substances, such as creatinine, and exogenous substances, which are injected into a vein for this purpose, such as radioisotopes  iohexol .Creatinine clearance has established itself as a measure of GFR mainly due to the determination of creatinine, which is one of the oldest and most common laboratory tests. The determination is also easier than the measurement of the clearance of exogenous substances, and is more affordable. Creatinine is an endogenous product of creatine and phosphocreatine metabolism in muscles and reflects muscle mass. The concentration of creatinine in the blood is fairly constant. Creatinine is filtered in the glomeruli and secreted in the proximal tubules. Non-glomerular excretion is negligible in healthy individuals, but in patients with advanced CKD, this proportion may be higher resulting in falsely higher GFR values. Cimetidine can be added for research purposes, as it occupies the receptors for creatinine in the tubules and prevents tubular secretion .For the examination, a 24-h urine collection and the plasma creatinine value, as well as the subject’s weight and height, are required. If the examination is carried out in children who cannot hold urine, a urinary catheter must be inserted.Renal clearance of inulin is the gold standard for determining the GFR in children and adults. Inulin does not bind to plasma proteins and is freely filtered through the glomerular membrane. The classic form of measurement of inulin clearance requires an intravenous injection of an initial dose of inulin followed by a steady 2- to 3-h infusion of inulin to achieve a constant plasma concentration for the required 45 min . Urine iThis method of measurement is still the gold standard for determining GFR, but it is technically very demanding. In addition, not all laboratories are equipped to measure the concentration of inulin, and the procedure is expensive .in) can also be determined by taking blood and determining the serum concentration of inulin (Sin) after establishing the equilibrium state of inulin in the plasma, taking into account the speed (H) and concentration of inulin in the infusion (Iin) [in—mL/min; Iin—mg/mL; Sin—mg/mL; H—mL/min.The plasma clearance of inulin (Con (Iin) : Cin=IinBy determining the plasma clearance of inulin, the procedure is somewhat simplified, as urine collection is not required. Swinkels et al. tried the latter in children with a single administration of inulin and as little blood sampling as possible. With blood sampling, we determine the elimination curve, which can be divided according to the two-space model into the distribution phase, when inulin is distributed from the intravascular to the interstitial space, and the elimination phase, when the concentration in the blood decreases at the expense of renal excretion . They foIohexol is a nonionic contrast agent with low osmolarity. It is used intravenously in much higher doses for radiological diagnosis and interventions even in the presence of kidney disease, as it is not absorbed, metabolised or excreted by the kidneys. The molecular weight of iohexol is 821 Da and it is a cheap and standardised preparation that has been used in medicine for a long time. Caution is required only in patients who are allergic to iodine. To measure GFR with iohexol, plasma clearance of the substance is used . It is e51Cr-EDTA measurement. Sufficient time must elapse from intake to estimation of GFR using a unicompartmental model, especially in low GFR or preterm infants [In the initial research, Schwartz et al. showed that the GFR measurement with iohexol is effective after a single dose of iohexol with nine blood samples taken at 10, 20, 30, 60, 120, 180, 240 and 360 min . They alThere is currently no standardised procedure for measuring GFR with iohexol. However, there are several studies of measurements using different protocols and different numbers of samples in children; in some, it was also compared with renal creatinine clearance ,25,26,27Several studies and commentaries have been published regarding the use of iohexol as a means of measuring GFR in children, confirming its usefulness in determining the degree of CKD. Currently, there are discussions regarding the standardisation of the method and the number and method of sampling for all children with CKD .51Cr-EDTA is 0.6 mSv and the radiation with 99mTc-DMSA is 0.05 mSv in an adult. Recently, they have been less available in Europe [These radioactive molecules have been used for a relatively long time to determine GFR. EDTA and DMSA are similar binding molecules that carry a radioactive element suitable for measurement. They bind poorly to plasma proteins and are mostly filtered through the kidneys. At appropriate doses, the radiation with n Europe . Renal cn Europe .After the intravenous injection of the radiopharmaceutical, several blood samples are taken, and by measuring the radioactivity of the sample over time, the curve of its elimination rate is determined. The slope of the curve depends on the clearance of the radiopharmaceutical. Radiopharmaceuticals for determining GFR and effective plasma flow through the renal parenchyma are labelled with different radioisotopes; so, with nuclear medicine methods, both measurements can be performed simultaneously, and the filtration fraction (FF) calculated. FF is defined as the ratio between GFR and effective plasma flow through the renal parenchyma. Normally, it is 0.20–0.30 .The GFR estimate is based on a calculation using an endogenous marker such as creatinine or cystatin C. The calculations are based on population calculations and can be quite complex, but it is important that the method for the determination of the marker is the same as provided for the equation. In the past, the classic Jaffe reaction was mostly used to determine creatinine, but the result was affected by the presence of many substances . However, with modifications of the method, its specificity has increased. Isotope dilution mass spectrometry has been adopted worldwide as the reference (definitive) method for determining serum creatinine. For better comparability between laboratories, an international standard for creatinine—SRM 967, prepared in 2004—enables traceability to this standard and is followed by most manufacturers of laboratory equipment. Only based on traceability to the standard can the serum creatinine concentration values of a certain laboratory be “trusted.” As an optional working method, laboratories were advised to use an enzyme reaction, which is specific but more expensive; hence, the modified Jaffe reaction, which is adequate in the case of traceability to the standard, is still mainly used. Such an agreement was also adopted in Slovenia and has been gradually implemented in practice since 2009 [2 of body surface area.The Cockcroft–Gault (CG) equation was based on a 1973 study of 249 men with a measured creatinine clearance of 30–130 mL/min. It is used to estimate creatinine clearance (Clcreat), but not GFR. When using this equation, age, sex, body weight and serum creatinine (S-creatinine) concentration are considered. For women who were not included in the research, a correction factor was introduced based on the fact that in women, due to their lower body weight, the production of creatinine in the body is 15% lower than in men.The equation systematically overestimates GFR and additionally overestimates GFR in vegetarians, obese and oedematous patients and people on low-protein diets. GFR is underestimated in young people and patients with CKD . Because2. It was originally intended for the Jaffe method of creatinine determination, so in 2005 the factor was updated from 186 to 175 [2; serum creatinine (Screatine)—μmol/L); age—years.This equation is a by-product of a large 1999 study on the impact of diet on CKD, which included 1628 patients. In addition to the creatinine value, it also considers the subject’s gender, age and ethnicity. The eGFR is expressed for an average body surface of 1.73 m6 to 175 .eGFR=17The equation is often used for adults and is less accurate in younger patients and in patients who do not have CKD, such as younger patients with type 1 diabetes and potential kidney donors .2 are as accurate as eGFR MDRD, but above this range, eGFR CKD-EPI is more accurate. Using the CKD-EPI equation, compared to the MDRD equation, the proportion of people with eGFR < 60 mL/min/1.73 m2 is reduced by 10%, especially in those under 60 years of age, and thus as many as 35% fewer people have eGFR < 60 mL/min/1.73 m2. Recently, therefore, instead of the MDRD equation, the CKD-EPI equation [The CKD-EPI equation was created in 2009 and is based on the same variables as the MDRD equation but is more complex. The study included CKD patients, diabetic patients, kidney transplant patients and healthy people, improving the accuracy of the GFR estimation in these human populations. When determining eGFR CKD-EPI, eGFR values below 60 mL/min/1.73 mequation .2 and includes the factor k, which depends on age and is 0.33 for prematurely born children up to 1 year of age, and 0.44 for full-term children. From one to thirteen years, the factor is 0.55 for both sexes, and for adolescents, it is 0.70 for men and 0.55 for women [2; body height—cm; serum creatinine (Screat)—μmol/L.This equation, which is also used in children, includes body height, which is used to predict muscle mass and thus also estimates creatinine excretion from muscles. The value of eGFR is given in mL/min/1.73 mThe equation was designed to estimate GFR in children and is therefore the most widely used bedside equation for estimating GFR in children. Due to its reliance on serum creatinine, it is quite inaccurate in children with a low muscle mass, and is also significantly affected by protein intake. Compared with GFR measured with iohexol, this equation was found to overestimate GFR .2; body height—m; serum creatinine (Screat) (μmol/L); serum concentration of urea (Surea)—mg/dL; serum concentration of cystatin C (ScistC)—mg/L.Based on a more recent CKiD study, an updated Schwartz equation was constructed in 2009, which also considers the enzymatic method of determining creatinine and, in addition to serum creatinine, includes the serum value of urea, cystatin C and gender :eGFR=39.Since the latter is much more complicated, it was converted into a bedside equation for the sake of simplification:2 and probably even at a GFR above 90 mL/min/1.73 m2. Since the calculation was performed on a group of children with GFR up to 75 mL/min/1.73 m2, when calculating with these equations, >75 mL/min/1.73 m2 are given as higher values.The CKiD equation compared to the measured GFR with iohexol correlated with R = 0.85, and the mean error was −1.60 mL/min. The bedside version of the equation correlated with the measured GFR with a coefficient of R = 0.84 with a mean error of 1.75 mL/min. Both equations give very accurate GFR estimates in the range of 15–75 mL/min/1.73 m2; body height—m; serum creatinine (Screat)—μmol/L; serum concentration of urea (Surea)—mg/dL; serum concentration of cystatin C (ScistC)—mg/L.In 2012, the equation was corrected for the nephelometric method of measuring cystatin C :eGFR=39.Cystatin C is a protein from the group of cysteine protease inhibitors. It is produced in all nucleated cells at a constant rate and has a low molecular weight. It is found mainly in extracellular fluids, i.e., in blood, cerebrospinal fluid and seminal fluid. It is filtered in the glomeruli, and is not secreted in the tubules, but is completely resorbed and degraded in the proximal tubules. Therefore, it no longer passes into the bloodstream and is thus a suitable endogenous marker for GFR assessment. Unlike serum creatinine, cystatin C is not affected by age, sex, muscle mass, body composition, inflammatory processes or diet .In the absence of renal disease, the serum concentration of cystatin C is increased in patients with liver disease, thyroid disease and during treatment with glucocorticoids . Since iSeveral equations have been published to estimate GFR using the cystatin C level, and in some equations already mentioned, the serum cystatin C level is used together with the serum creatinine level to estimate GFR:CKiD-2012, Schwartz et al. : eGFR=70Zapitelli et al. : eGFR=75Filler et al. : eGFR=91Units: serum level of cystatin C (ScistC)—mg/L.According to the above equations, it is clear that in all cases, it is a mathematical derivation of the measured GFRs. The estimated GFR using cystatin C is more accurate than using creatinine in children younger than two years. The equations also differ due to the different times of formation and therefore there is no standardised determination of cystatin C .A study was conducted to assess GFR in newborns, which also takes ultrasound-measured kidney volume into account :eGFR = [The basic characteristics of children is their growth and development, therefore not all the described methods are appropriate in every age.Neonates, especially preterms, are unique in their physiological changes. Normal variations of serum creatinine and cystatin C should be considered. At birth, serum creatinine is elevated due to its placental passage during pregnancy, and does not properly reflect GFR. Therefore, serum creatinine does not present the best marker for GFR estimation after birth; however, its level might be useful in observing its dynamics—an additional rise or failure to fall appropriately might indicate an acute kidney injury, to which neonates are especially prone to . On the After that, the decision on the form of determination of GFR is based on the clinical state of the patient. Guidelines recommend the use of the creatinine-based updated Schwartz formula in children , which u2. It has been hypothesised that this is the consequence of the lower reabsorption capacity of the nephron for beta-trace protein. It also has a large molecular size, and it does not cross conventional haemodialysis membranes, which makes it a useful marker of residual renal function in dialysis patients [Along with creatinine and cystatin C, other endogenous molecules are being researched. The measurement of an endogenous marker is preferred due to the less invasive and demanding procedure along with endogenous markers being always accessible in contrast to some exogenous markers, such as inulin. Thus, research into beta-trace protein and beta-2 microglobulin as endogenous markers of kidney function has increased. Beta-trace protein is synthesised mainly in the central nervous system and forms one of the principal constituents of the cerebrospinal fluid, where its concentration is the highest. Some of the protein also originates from the kidneys, genital organs and heart; it is subsequently metabolised by the liver and eliminated almost exclusively via the kidneys. It has been found to be an early marker of impaired kidney function with urinary excretion inversely related to GFR. It was increased when the GFR fell below 90 mL/min1.73 mpatients . Beta-2-microglobulin on the other hand is a small protein found on the surface membrane of nearly all nucleated cells. It is shed during membrane turnover and can be detected in various fluids with the highest concentrations in serum and synovial fluid. It is reabsorbed and catabolised in the proximal tubules. Elevated urine concentrations are indicative of tubular dysfunction, and are also linked to viral infections, inflammation and various types of malignancy. It does not cross the placental barrier and can therefore be used as a parameter of foetal renal function. Otherwise, it is unclear whether the determination of its concentration adds significant benefit in the paediatric population . Other novel biomarkers of tubular injury, including neutrophil gelatinase-associated lipocalin (known as NGAL), kidney injury molecule-1, liver-type fatty acid binding protein, N-acetyl-β-(D)-glucosaminidase, interleukin-18 and urinary epidermal growth factor ,44,45, wIn addition, we hope that research will also continue in the fields of accurate, child-friendly GFR determination and early renal risk detection.The value of GFR can be accurately determined by measuring GFR with exogenous substances, which are the gold standard. Recently, radioactive markers have been increasingly replaced by the non-ionising marker iohexol. In the clinical context, it is important to utilise a method that has good accuracy but is not too burdensome for patients of all ages. In our practice, we obtained diametrically different results of GFR estimation from creatinine or by measuring creatinine clearance from 24-h urine collection. In patients with persistent discrepancies in GFR measurements with CKD, we measured iohexol clearance. In our hospital, the GFR value is determined with iohexol in both children and adults, mostly with five blood samples, but protocols with a smaller number of samples are being developed. The measurement of GFR with iohexol is a welcome innovation in our clinic to assist in the assessment of the progression of CKD. The assessment of GFR based on the serum creatinine level has already been implemented in the laboratory system, and reference values are considered when determining serum cystatin C. Accurate determination with exogenous markers is especially important for assessing the progression of CKD in children, which, as a rule, does not show other clinical signs in the early stages. Further assessment of other potential, possibly endogenous markers of kidney function is needed.