The definition of cerebral perfusion pressure (CPP) secondary insults in severe traumatic brain injury remains unclear. The purpose of the present study is to visualize the association of intensity and duration of episodes below or above CPP thresholds and outcome. The analysis was based on prospectively collected minute-by-minute intracranial pressure (ICP) and blood pressure data and outcome from 259 adult patients. The relationship of episodes of CPP below or above a certain threshold for certain duration with the 6-month Glasgow Outcome Score was visualized separately for episodes of active or deficient autoregulation (AR). In adults ≤65 years, an almost exponential transition curve separates the episodes of CPP associated with better outcomes from the episodes of low CPP associated with worse outcomes, indicating that lower CPP could only be tolerated for a brief time. Analysis of episodes of high CPP again showed a time-intensity dependent association with outcome. When combining the two plots, a safe CPP zone between 60 and 70 mm Hg could be delineated—however, only for AR active insults. The AR status predominantly affected the transition curve for insults of low CPP. Episodes with ICP >25 mm Hg were associated with poor outcome regardless of CPP. In the present study, the CPP pressure-time burden associated with poor outcome was visualized. A safe zone between 60 and 70 mm Hg could be identified for adults ≤65 years, provided AR was active and ICP was ≤25 mm Hg. Deficient AR reduces the tolerability for low CPP. In Europe, the overall incidence of fatal and hospitalized TBI is 262/100,000/year.1 An estimated 43.3% of hospitalized patients with TBI in the United States experience long-term disability.2 The management of severe TBI focuses on avoiding additional ischemic damage from preventable or reversible secondary insults. Intracranial hypertension has long been identified as an insult associated with poorer outcomes.3–5 Therefore, it is recommended that intracranial pressure (ICP) be monitored in salvageable patients with severe TBI and to treat patients with ICP above 22 mm Hg.6 It is evident that “22” is not a magical number, and it was recently demonstrated by our group that the relation between ICP level and outcome is not only time dependent, but that ICP tolerability also depends on age and pressure autoregulation (AR) capacity.7T8 This capacity for “pressure AR” can be deficient after TBI.9 Moreover, with intact AR, low CPP can induce a vasodilatory cascade resulting in raised ICP.While the relation between ICP and outcome is still rather straightforward, however, guidelines on blood pressure management in severe TBI seem more difficult to produce. Cerebral perfusion pressure (CPP) is the driving force of cerebral blood flow, expressed as the difference between the mean arterial blood pressure (MAP) and ICP. Within a certain range of CPP, the cerebral vasculature has the ability to maintain constant cerebral blood flow, which is—among others—based on alterations in basal tone and subsequent diameter changes of pial arterioles.10 to formulate the recommendation that CPP in severe TBI situations should be kept above 70 mm Hg. This concept, however, could not be demonstrated to produce better outcomes in a randomized controlled trial.11 At the same time the Lund concept, which emphasized avoidance of the use of vasopressors and accepted CPP down to 50 mm Hg for adults, did not result in poorer outcomes.12 An explanation for this apparent paradox was sought mainly in the dynamic, and hence more complex, behavior of pressure AR capacity or deficiency after TBI.14The latter phenomenon led Rosner and associates14 or Low frequency Autoregulation Index (LAx)15 has enabled the identification of CPP ranges in which AR is more active,15–17 and in retrospective series, higher percentages of time of actual CPP contained within these zones were associated with better outcomes.18 At present, pressure reactivity monitoring is predominantly performed in centers with a research interest in severe TBI.Real-time monitoring of cerebrovascular pressure reactivity through parameters such as the Pressure Reactivity Index (PRx)6 For a parameter subject to variability such as CPP, however, it may be helpful to the clinician to have more insight into the burden on outcome of CPP insults in terms of severity and duration.In the latest version of the Brain Trauma Foundation guidelines, the chapter on CPP thresholds is limited to a level IIB recommendation that the CPP value to target lies within the range of 60 to 70 mm Hg.The aim of the present study is to assess the effect of CPP insults, according to varying definitions of intensity and duration, on functional outcome at six months based on prospective data from continuously monitored adult patients with severe TBI. In addition, the impact of ICP, cerebrovascular AR, age, and decompressive craniectomy (DC) on the capacity to tolerate the CPP insults is investigated.19 a multicenter data collection between March 2003 and July 2005 . The Multi-Centre Research Ethics Committee for Scotland MREC/02/0/9 granted the use of these data for scientific purposes on February 14, 2002.• There were 164 patients included from the Brain-IT database,• The data of the remaining 95 adult patients were collected from four centers: 38 from the San Gerardo Hospital in Monza, Italy, between March 2010 and April 2013; 25 from the University Hospitals, Leuven, Belgium, between September 2010 and September 2013; 20 from the University Hospital, Antwerp, Belgium, between May 2010 and June 2013; and 12 from the University Hospital, Tübingen, Germany, between February and December 2009. Local Ethical Committee approval to use the anonymized data for this analysis was obtained in all centers.The study population consisted of 259 patients with severe TBI aged 16 years and older:19 For the later cohort, data were recorded through the centers' Patient Data Management System, in minute-by-minute resolution in Leuven, Tübingen, and Monza, and in second-by-second resolution in Antwerp. For the Antwerp patients, the median value per minute was used in this analysis. Minute-by-minute signals from all data sets were reviewed independently by two senior clinicians in Leuven , and obvious artifacts at visual inspection of data traces were removed.Data collection included baseline risk factors , admission pupil reactivity), and minute-by-minute ICP and MAP monitoring data. Monitoring data were recorded in minute-by-minute resolution through specifically designed “BrainIT data collection software” for the BrainIT study.Finally, a correction of the CPP values for arterial blood pressure transducer height was made based on the information that was obtained on the height of the arterial blood pressure transducer and of the head of the bed. For patients in whom the transducer was at cardiac atrium level and who received nursing care with the head of the bed elevated at 30 degrees, 10 mm Hg was subtracted from the registered CPP. This was the case in 101/259 patients (39.0%).n = 179), patients >65 years who did not undergo DC (n = 35), and patients ≤65 years who underwent DC (n = 37). The details of the three groups are presented in To investigate the effect of DC and old age on the capacity to tolerate CPP insults, the analyses were performed separately for three groups: patients ≤65 years who did not undergo DC .7 was applied in the current analysis investigating the relationship between CPP and outcome. For CPP, two types of insults are defined: insults characterized by CPP dropping below a certain pressure value for a certain duration of time as well as insults characterized by CPP exceeding a certain pressure value for a certain duration of time. Hence, the visualization was performed separately for insults of low CPP and insults of high CPP. The Pearson correlation coefficient between the number of insults of a certain intensity and duration and GOS was expressed by a graded color code: negative correlations in red (−1 in dark red) and positive correlations in blue (+1 in dark blue). The contour for zero correlation was highlighted in black and defined as the “transition curve.” For more details about the visualization method, we refer to Güiza and coworkers.7 Analytic routines were programmed in Matlab® .The method developed in our group for visualizing the univariate association between insult and outcome and that was used for assessing the pressure and time burden of intracranial hypertension in Güiza and colleagues15 The LAx was calculated at every minute during the monitoring period and average LAx for every CPP insult period, which allowed for discriminating CPP insults associated with “active” AR (if average LAx <0) or “passive” AR (if average LAx ≥0). Hence, the relationship between CPP insults and outcome was visualized separately considering active or passive episodes exclusively.The LAx, expressing cerebrovascular pressure reactivity as an indicator of pressure AR, is calculated as the moving median of the correlation coefficients between ICP and MAP for the past time intervals of 3, 5, 10, 20, 30, 60, and 90 min, using minute-by-minute resolution data.7The relationship between CPP insults and outcome was visualized separately for CPP insults associated with average ICP ≤25 mm Hg and for CPP insults associated with average ICP >25 mm Hg to examine the relative effect of ICP and CPP insults on outcome. The value of 25 mm Hg was chosen as the discriminator because ICP above 25 mm Hg was associated with poor outcome independent of the insult duration in our ICP article.21 The percentage of monitoring time spent in the red zone was based on a new calculation, in which for each patient, for every minute of monitoring it was checked whether this minute fulfilled criteria of belonging to one or more of the several episodes negatively associated with outcome . The time in the red zone was then divided by the total monitoring time of that patient.Multivariate logistic regression models for death were calculated to investigate the independent association of the cumulative dose of CPP insult burden with outcome. Therefore, the percentage of total monitoring time each patient had CPP insults associated with worse GOS  was used as an independent variable, together with the IMPACT model core variables age, pupils, and admission Glasgow motor score.22 To assess whether CPP policy confounded the current analysis, the median of the patients' median CPP was calculated per center. For the two centers that contributed data to the cohort before and after 2007, the median was calculated separately for the patients of both periods. Next, the visualization method was applied separately for centers with a median CPP below and above 70 mm Hg to assess its validity independent of CPP policy.The database contains patients treated before and after the publication of the third revision of the Brain Trauma Foundation guidelines in 2007, in which the recommendation to aim at CPP higher than 70 mm Hg was abandoned.n = 179), the visualization of the association between GOS and the intensity and duration of CPP insults is shown in For adults ≤65 years who did not undergo DC . In active episodes, there was a pronounced shift to the left of the transition curve for low CPP, while the transition curve for high CPP slightly shifted to the right, resulting in a zone between 60 and 70 mm Hg in which CPP was associated with better outcome up to 360 min. In passive episodes, the transition curve for high CPP remained fairly constant, but the transition curve for low CPP showed a pronounced shift to the right, resulting in the finding that no CPP value was associated with good outcome for longer than 90 min.In n = 35), no transition curves could be discerned, outcomes being overall poor (see ftp.liebertpub.com). In adults ≤65 years who underwent a DC (n = 37), no meaningful transition curves could be identified either (see ftp.liebertpub.com). The percentage of monitoring time with active AR was 44.5% for the adults ≤65 years without DC and 38.2% for the elderly without DC.As for elderly persons >65 years without DC (ftp.liebertpub.com).Nine centers had a median of patients' median CPP below 70 mm Hg and 11 above 70 mm Hg . When thp = 0.04, ftp.liebertpub.com).In the multivariate analysis, the percentage of monitoring time each adult spent in the red zone (based on the transition curves of the active adults ≤65 years without DC) was an independent predictor of mortality  plateau regardless of MAP in the Lassen representation.8 has been criticized as an oversimplification and more importantly because it was based on a disputable methodology of grouping populations from different studies.24 From physiological research, AR emerges as a complex feedback mechanism with overlapping and interacting pathways, including intrinsic vasomotor mechanisms, peripheral autonomic vasomotor regulations, and central intrinsic neural pathways. The actual intra-individual range of effective AR is thought to be as narrow as approximately 10 mm Hg.25 Also, AR would seem to be better at buffering increases versus decreases of MAP,27 which is inverse to our observation that AR had the most pronounced effect on the “tolerance curve” for low CPP. Noteworthy, the effect of AR on the transition curve for low CPP in the present analysis concerns a wider pressure range than the effect of AR on the ICP transition curve in Güiza and associates.7The Lassen representation of the cerebrovascular AR as a CBF plateau for MAP between 60 and 150 mm Hg29 In active AR, a safe CPP zone between 60 and 70 mm Hg for up to 6 h is depicted in the current study. How this safe zone looks like for longer periods cannot be concluded from the present study. Variability of blood pressure and ICP in real life, as in the present study, however, may question the relevance of this issue. The safe zone is congruent with the AR stable CBF plateau concept, but a dynamic component is added—i.e., the actual range of safe CPP is wider than 60 to 70 mm Hg, but outside the 60 to 70 mm Hg, it is time dependent.In several studies, it has been reported that the impairment of AR in TBI is a dynamic phenomenon.16–18 First, there is a different perspective. The optimal CPP method searches for CPP values associated with active AR (based on PRx or LAx) and then finds a relationship with outcome. The current study investigated the relationship between CPP and outcome and then looked at the influence of AR (using LAx). Second, associations with favorable outcome can be found far outside the 60 to 70 mm Hg range, but then they are time dependent. The optimal CPP method, within the scope of the CPP range the patient has been in, will pick up time-dependent CPP zones associated with active AR in this wider range. Future studies, both clinical studies as well as validation studies of clinical tools in animal AR models, will be required to refine our understanding of AR and optimal CPP. What can be concluded from the current article and our ICP article7 is that active AR improves the tolerability for insults of high ICP and low CPP. Consequently, it is likely beneficial to bring the patient with TBI in a state of active AR.This is not in conflict with the literature on optimal CPP.7 That the impact of high ICP on outcome overrules the effect of CPP, however, should not be interpreted as if the management of CPP is unimportant during episodes of high ICP. It may well be that, more than the pressure level itself, high ICP reflects the global seriousness of the patient's condition, and hence is reflected in its profound relationship with poor outcome.Insults of CPP <50 mm Hg were hardly tolerated, and ICP >25 mm Hg was associated with poor outcome regardless of CPP. The latter two findings were also demonstrated in Güiza and coworkers.ftp.liebertpub.com). Fifth, artifacts in the monitoring data were manually removed by two clinical experts, and we cannot exclude that some artifacts went unnoticed. Sixth, although the results seemed robust, we cannot exclude an influence from confounders that were not analyzed. Also, it should be kept in mind that this analysis reports on correlative and not necessarily causative relationships. Seventh, AR was considered as active (LAx negative) or passive (LAx positive), while in reality it does not behave as an on-off phenomenon, and the threshold of “0” is debatable. Moreover, it should be taken into account that LAx produces a rough estimation of changes of AR capacity over longer periods, with lower resolution than the actual phenomenon. Finally, LAx may behave noisy when only considered in short time intervals, which should be taken into account when interpreting the influence of AR on the very short CPP insult periods.The current study inevitably has limitations. First, the sample size remains relatively small. Second, the data incorporate therapeutic influences, which cannot be removed. As we have shown, however, CPP policies did not affect the CPP/outcome transition curves. Third, although efforts were made to correct for the height at which arterial blood pressure was zeroed, some degree of uncertainty cannot be excluded. When we analyzed the data without correction, however, the influence on the graphs was minimal and the interpretation remained similar. Fourth, longer-staying patients have a proportionally higher representation in the total monitoring time. To rule out bias from this phenomenon, the visualization plots were recalculated using daily averages of the number of insults. The graphs remained unchanged  monitoring tools.


To establish the independent association between blood pressure (BP) and retinal vascular caliber, especially the retinal venular caliber, in a population of 12-year-old Chinese children.0 fundus images of the right eyes. Retinal vascular caliber was measured using a computer-based program (IVAN). BP was measured using an automated sphygmomanometer .We have examined 1501 students in the 7th grade with mean age of 12.7 years. A non-mydriatic fundus camera  was used to capture 45P for trend< 0.05). Each 10-mmHg increase in BP was associated with narrowing of the retinal arterioles by 3.00 μm (multivariable-adjusted P < 0.001), and the results were consist in three BP measurements. The association between BP measures and retinal venular caliber did not persist after adjusting for fellow arteriolar caliber. And there was no significant interaction between BP and sex, age, BMI, and birth status.The mean retinal arteriolar caliber was 145.3 μm  and the mean venular caliber was 212.7 μm . After controlling for age, sex, axial length, BMI, waist, spherical equivalent, birth weight, gestational age and fellow retinal vessel caliber, children in the highest quartile of BP had significantly narrower retinal arteriolar caliber than those with lower quartiles (In a large population of adolescent Chinese children, higher BP was found to be associated with narrower retinal arterioles, but not with retinal venules. Sex and other confounding factors had no effect on the relationship of BP and retinal vessel diameter. Major component of the circulatory system is composed of the microcirculation, which plays an important role in maintaining cardiovascular health. There is a widespread influence of blood pressure (BP) on the structure and function of microcirculation system. Early in the late nineteenth century, Marcus Gunn had put forward the statement that there were associations between microvascular abnormalities and cardiovascular diseases .The retina is a unique structure of the eyes, where the in vivo microcirculation can be directly visualized and monitored non-invasively. Retinal microcirculation shares the same anatomic architecture and physiological feature with other terminal organs elsewhere in the body . These cDespite increasing data on the risk prediction of retinal vascular caliber measurement in different population-based studies, there had been still some controversial opinions on association between retinal vascular changes and BP, especially for the retinal venular changes. Understanding the impacts of BP and changes to the retinal microvasculature in persons with different background is an important aspect of the study on microcirculation disease. Children are generally free of many systemic conditions and eye diseases  that could bring about confounding effects on observed associations. High BP in children and adolescents is more and more common in western countries , and BP In this study, we investigated the independent association between blood pressure measures and changes to the retinal microvasculature in a relatively large population of 12-year-old Chinese children. This study also assessed the potential modifying influences of age, BMI, birth parameters, especially sex, on the associations between BP and retinal vessel caliber.The Anyang Childhood Eye Study (ACES) is a school-based cohort study designed to observe the occurrence and development of myopia as well as other diseases in school children living in Anyang urban area, Henan Province, Central China. Detailed methodology of the study has been previously described . In brie0 fundus images centering on optic disc and macular area of children’s right eyes by a well-trained operator [The children were examined at health examination station of the Anyang Eye Hosptial. A non-mydriatic fundus camera  was used to capture 45operator . ChildreAccording to a standardized protocol described previously , the comBlood pressure of children was measured in a seated position after 5 min of rest using an automated sphygmomanometer  with appropriate cuff size . Systolic and diastolic blood pressure  readings were taken. Two readings were taken 5 min apart and averaged for analysis. Mean arterial blood pressure (MABP) was computed as 2/3 of the diastolic plus 1/3 of the systolic value.2 (kg/m2). Waist circumference was measured with a tape measure and was defined as the narrowest part of the student’s trunk. Birth information including gestational weeks, birth weight and birth length were collected by administrating questionnaires to the participating students’ parents.Any abnormality of anterior segment  was observed and recorded using a slit-lamp . Cycloplegic spherical equivalent refraction was measured using an autorefractor  with three readings taken and averaged. An optical coherence biometry  was applied to evaluate the optical axial length (AL) value along the visual axis , with five repeated measurements taken and averaged. Height and weight were measured using an automatic and professional integrated set. Body mass index (BMI) was calculated as weight/heightP value was defined as < 0.05.SAS  was used to perform statistical analysis. BP was categorized into quartiles as well as being analyzed as a continuous variable (i.e. each 10 mmHg increase). The retinal arteriolar, venular calibers, and arteriolar to venular ratio (AVR) were compared across blood pressure quartiles based on three models, Model 1 was analyzed without any adjustment, Model 2 adjusted for multivariate variables  and then Model 3 adjusted additionally for fellow retinal vessel diameter. The test of trend was determined by regarding quartiles of BP as continuous ordinal variables. Multiple linear regressions were used to estimate the absolute changes in retinal arteriolar and venular caliber for a 10-mmHg increase in SBP, DBP, and MABP. Potential modifiers were examined in stratified analyses of age, sex, BMI, and birth parameters. All probabilities quoted are two-sided, and a significant Table P < 0.01), with a mean difference of 6–7 μm between the highest and lowest quartiles, and the results were consistent for three BP measurements. As for retinal venular diameter, in Model 1, children with higher BP had significantly narrower CRVE (P < 0.001 for trend for three BP measurements), and in Model 2, only children with higher SBP were found to have narrower CRVE than those with lower SBP (P = 0.038 for trend), however, this association did not persist after adjusting for fellow vessel caliber. In Model 1 and Model 2, children with higher BP quartiles had consistently and significantly narrower AVR (P < 0.001 for trend), and the results were consistent for three BP measurements.Table P < 0.001) and CRVE decreased by 1.47–2.69 μm (P < 0.001). In model 3 adjusted for fellow vessel caliber additionally, each 10-mmHg increase in BP was associated with 2.34–3.47 μm decrease in retinal arteriolar caliber (P < 0.001), but no significant change in CRVE (p > 0.42) was observed. AVR decreased by 0.010 to 0.014 for every 10-mmHg increase in BP in Model 1, Further adjustment for age, gender, axial length, BMI, waist, spherical equivalent, birth weight and gestational age had no impact on the magnitude of this effect (AVR reduction 0.007 to 0.012).Table Subgroup analysis stratified by potential effect modifiers was presented in Tables P < 0.001) and 2.73–3.89 μm (P < 0.001) decrease in CRAE for boys and girls respectively, and in model 3, the decrease of CRAE reduced to 2.57–3.81 μm (P < 0.001) and 2.12–3.12 μm (P < 0.001) for boys and girls respectively (Table P < 0.05) decrease for boys and 2.15–2.76 μm (P < 0.05) decrease for girls in model 2, but when CRAE was additionally adjusted in model 2, there is no significant association between BP and CRVE in either boys nor girls, which was consistent in three BP measurements , but was only of borderline significance among boys , after analyzing a population-based sample of 3248 children in National Health and Nutrition Examination Survey (NHANES) III (1988–1994) and 8388 children in continuous NHANES (1999–2008), aged 8 to 17 years [First, at present, there were some epidemiological studies on adolescent BP, but these studies had not reached the uniform conclusion related to the gender difference. Some studies showed a higher frequency of elevated BP in males than in females in children population based research , but the17 years . The femSecond, in the SCES, with regard to the mechanism underlying the conclusion that higher blood pressure was associated with wider retinal venules in boys, the author deduced that maybe it was because sex hormones had an protective effect on the retinal circulation, as a proportion of girls would have commenced puberty. But it was interesting that Zou found that in 76,869 Chinese girls, the rate of high blood pressure in menstruation group from 11 to 13 years was significant higher than that in the same age group of non-menstruation . SimilarP < 0.0001). Obesity might influence the change of blood pressure by some mechanisms such as glomerular and tubular effects, and some of these mechanisms are sex dependent [Third, the prevalence of child obesity is increasing rapidly worldwide, and the BMI may play an active role in the result of association of blood pressure and CRVE. Although a lot of literatures showed that the BMI was higher among boys than that of girls , Cole TJependent . In the Forth, lack of regular moderate-to-vigorous intensity physical activity is a well-known risk factor for cardiovascular disease, increasingly amount of studies have been focusing on the relationship between physical activity and retinal microcirculation and cardiovascular diseases . PhysicaIn addition to the reasons analyzed above, the association between blood pressure and retinal venular caliber might be affected by other factors such as smoking status , geneticIn the past, researchers had generally attributed a lower arteriolar-to-venular ratio (AVR) to generalized arteriolar narrowing and suggested that this ratio may provide information that would predict incident cardiovascular diseases. But with the advent of semi-automatic examination, it makes it possible to measure arteries and veins in retinal fundus separately. Since 2004, Ikram  and otheOur results once again stressed the necessity of additional adjustment of concomitant vessels. We found a relationship between higher SBP and smaller CRVE, however, when CRAE was added to the final multivariate-adjusted model (model 3), the relationship between SBP and CRVE became nonsignificant, and further adjustment of the caliber of the CRVE diminished the reduction magnitude of CRAE when BP increased, suggesting the possibility of a confounding effect of fellow vessel caliber on this association. A significant association between narrower venular caliber and hypertension was initially reported in the Rotterdam Eye Study , but thiStrengths of this study include its random cluster sample of a large number of representative healthy schoolchildren. The samples were free of influences from systemic disease processes or eye diseases on retinal vessel measurements. We also used a previously validated standardized protocol of quantitative retinal imaging program for retinal vessel measurement. However, some potential limitations of our study demand consideration. First, the study design is cross-sectional and does not provide temporal information on the associations. Second, the possible selection bias giving rise from the exclusion of students by ineligibility and ungradable retinal photographs may play a part on the real association between BP and retinal vessel diameters. Finally, we failed to acquire further information from our samples such as smoking status, family history, blood lipid levels, blood glucose, which may have an impact on the results.In conclusion, this study shows that in population of 12-year-old Chinese children, increasing blood pressure was significantly associated with narrower retinal arteriolar caliber but not with retinal venular caliber, and possible confounding factors such as sex et al. had no effect on the relationship between BP and retinal vessel diameters. This finding provided further insight into the relationship of elevated BP on the microcirculation that occurs in early life. The association of wider retinal venular caliber and hypertension has not yet been consistently found, which should remain one of our highest research priorities.


Higher serum BDNF was an independent factor for greater reduction in pulse pressure . Using a receiver operating characteristic curve analysis, serum BDNF >20.6 ng/mL predicted a pulse pressure reduction after a one-hour rest . In conclusion, higher serum BDNF predicted greater recovery of pulse pressure after a one-hour rest in female nurses after night shift work.Night shift work is associated with cardiovascular disease and central nervous system disorders in female nurses. Brain-derived neurotrophic factor (BDNF) exerts protective effects on neural and endothelial functions. This study examined the association between serum BDNF levels and pulse pressure after rest in female nurses working night shifts. In this study, blood samples were collected for BDNF measurement after a night shift when nurses had been working night shifts for three continuous weeks. Blood pressure was assessed before and after a one-hour morning rest within a week of resuming the night shift after one month without any night shift work. The pulse pressure of nurses  was significantly reduced  after rest, and serum BDNF were significantly and inversely correlated with pulse pressure changes ( According to the data from 39 hospitals in Taiwan, approximately 40% of female nurses had performed night shifts for more than 10% of their total work time2. In other reports from the NHS I, night shift work was significantly associated with coronary heart disease and ischemic stroke in female nurses4. Night shift work was recently reported to be significantly associated with all-cause mortality and cardiovascular mortality in female nurses who were followed for 22 years5.Night shift work is inevitable for nurses caring for inpatients. Pooled data from the Nurses’ Health Study (NHS) I and NHS II show that approximately 60% of female nurses had experienced night shift work7. In one mouse study, the disturbance of circadian rhythms induced by exposure to light at night caused a depressive response8. Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, plays important roles in protecting neurons and synaptic activity9. A reduction in circulating BDNF level is associated with depressive symptoms12, and serum BDNF levels can reflect an improvement in depressive symptoms after lifestyle interventions14 or pharmacological treatments16.Rotating shift work is also associated with the central nervous system disorders17. In one recent cross-sectional study, lower circulating BDNF concentrations were reported to be associated with coronary artery disease18; in a prospective study, a lower BDNF concentration was reported to predict coronary heart disease and higher all-cause mortality19. Therefore, insufficient BDNF levels may play an important role in linking central nervous system disorders and arterial stiffness20.Notably, a low serum BDNF level is associated with forearm vascular resistance21, and a higher pulse pressure predicts a higher cardiovascular mortality rate23. According to studies that stratified by age, pulse pressure is a more powerful predictor of cardiovascular mortality in young subjects than in older subjects25. Furthermore, long-term reduction in pulse pressure is significantly associated with survival26. A short-term reduction in pulse pressure from peak exercise to rest is predictive of survival in subjects with normal myocardial perfusion imaging27, or after hemodialysis in patients with end-stage renal disease28.Pulse pressure, the difference between systolic and diastolic blood pressures, can reflect the severity of arterial stiffening30. According to Mathiassen et al.31 a delayed recovery of blood pressure increased by physical work was observed after a one-hour rest period. In the present study, we examined the relationship between serum BDNF levels and changes in pulse pressure after a one-hour rest period in female nurses working night shifts.Based on psychological stress, delayed recovery of systolic blood pressure after 45 minutes might predict the carotid intima-media thickness and hypertensionThis prospective observational study was conducted at Taichung Veterans General Hospital, Taiwan. The included subjects were female nursing staff members aged ≥20 years who worked in wards with a monthly rotating shift pattern. The exclusion criteria were (1) working night shifts at the time of the screening, (2) known diabetes mellitus, (3) established cardiovascular diseases, (4) current severe infection or inflammation, (5) a history of malignancy, (6) a history of psychological or mood disorder, (7) a history of substance or alcohol abuse, and (8) post-menopause or pregnancy. The study complied with the Declaration of Helsinki. All experimental protocols were approved by the Institutional Review Board of Taichung Veterans General Hospital and the written informed consent was obtained from all subjects. The methods were carried out in accordance with the approved guidelines.The aim of this study was to determine whether serum BDNF levels in female nurses who had worked a stable night shift predicted pulse pressure after a one-hour rest period when they rotated to the next night shift. The study subjects were screened when they were just before they rotated to night shift work for the following month. During the first night shift month, a three-week observation period confirmed that the subjects were performing their night shifts in a stable pattern. In the fourth week, the subjects were scheduled for a morning appointment after overnight fasting. Blood samples were collected to measure fasting glucose, insulin, lipid profile, serum creatinine, C-reactive protein (CRP) and BDNF levels after anthropometric measurements were obtained.After the first night shift month, the subjects underwent a wash-out period during which they did not perform night shift work for a month. The participants were scheduled for another morning visit during the first week of their rotation to a second month of night shift work after the one-month wash-out period. During this visit, blood pressure was measured at the right brachial artery, and the mean of two separate measurements with a interval of 1 min was recorded after the subjects had rested in a lying position for 10 minutes in the morning following the end of the night shift. Blood samples were not collected during this visit to avoid potential impacts of any invasive procedures on the blood pressure measurements. Then, the subjects were asked to take a nap on the same bed for one hour. After the nap, blood pressure was measured again.32. The estimated glomerular filtration rate (eGFR) was calculated as 186 × [serum creatinine (mg/dL)]−1.154 × [age (years)]−0.203 × 0.742 based on the Modification of Diet in Renal Disease (MDRD) equation33.Glucose levels were determined using an oxidase‒peroxidase method , and insulin levels were determined using a commercial immunoassay . Serum levels of creatinine and lipids were measured using commercial kits , and CRP levels were measured using an immunochemical assay with purified Duck IgY (∆Fc) antibodies . Serum human BDNF levels was measured using an enzyme immunoassay method . The intra‒ and inter‒ assay coefficients of variation for BDNF measurements were 4.1% and 9.0%, respectively. The sensitivity of the BDNF measurement was 0.02 ng/mL. The formula [fasting insulin (μU/mL) × fasting glucose (mmol/L)]/22.5 was used to calculate the homeostasis model assessment for insulin resistance (HOMA-IR) indext-test was used to detect significant differences between two groups. A paired t-test was used to detect significant differences in blood pressure before and after the one-hour rest. The correlation between serum BDNF levels and changes in the pulse pressure was determined using Pearson’s correlation coefficient. A multivariate linear regression analysis was used to assess the association between the changes in pulse pressure and serum BDNF levels. Statistical analyses were performed using SPSS version 22.0 software .Continuous variables are presented as the means ± standard deviations (SD). An independent samples A total of 53 female nurses were screened, of whom 48 completed the study assessments Fig. . Table 1According to the changes in pulse pressure after a one-hour rest, we divided the subjects into a pulse-pressure (P-P) reduction group n = 30) and a no P-P reduction group (n = 18). Table 0 and a nBased on the receiver operating characteristic (ROC) curve analysis, a cut-off value of 20.6 ng/mL for serum BDNF levels provided a sensitivity of 66.7% and specificity of 77.8% for differentiating a reduction in pulse pressure after a one-hour rest in nurses performing night shift work Fig. .Figure 434. Widening pulse pressure, resulting from a surge of systolic pressure against a non-compromised arterial wall followed by a low diastolic pressure, reflects the severity of arterial stiffness35. Arterial stiffness may involve not only the extracellular destruction of the vessel wall37, but also dysfunction of vascular smooth muscle cells38. Tropomyosin-related kinase receptor B (TrKB), a high-affinity receptor for BDNF, is expressed in the vascular smooth muscles40. Inactivation of the BDNF-TrkB signaling pathway in vascular smooth muscle cells may impair coronary vascular integrity and function41. Following treatment with empagliflozin, a sodium glucose co-transporter 2 inhibitor, higher BDNF expression was associated with the reduction of coronary arterial fibrosis in a diabetic mouse model42.The main finding in our study was that higher levels of serum BDNF levels in female nurses during night shift work predicted a greater reduction in pulse pressure after a short morning rest when rotating back to night shift work. Arterial stiffening describes the loss of the arterial wall’s elastic capacity to buffer the blood flow from ventricular ejection43. Increased arterial stiffness with decreased vascular activity, estimated using the reactive hyperemia index, has been found in subjects currently performing night shift work when compared with those not currently working night shifts44. Although the high blood pressure experienced during the work period normally decreases after a rest period, a delayed recovery of the high blood pressure during rest periods is more common in female nurses working night shifts than in those working day shifts45. High blood pressure may be the result of circadian disruption when rotating to night shift work. Kubo et al.46 also reported a reduction in the coronary flow reserve of the left anterior descending artery in female nurses the morning after working a night shift.Night shift work interrupts the circadian rhythm and may impair vascular functions controlled by autonomic activity47; however, the change in circulating BDNF was not reported. In the present study, coffee-consumption frequency did not significantly affect the serum BDNF (21.5 ± 5.3 ng/mL in the subjects who consumed coffee <1 time per month vs. 21.7 ± 7.5 ng/mL in the subjects who consumed coffee ≥1 time per month). Although the intake of a single-dose of coffee fruit extract was also reported to increase the circulating BDNF levels of healthy subjects within 120 min48, serum BDNF was assessed in a fasting state in the present study. This may explain why coffee consumption was not associated with serum BDNF levels in the present study. In contrast, it has been reported that arterial stiffness might be induced by either acute or chronic coffee consumption51. Souza et al.52 also reported that a single dose of coffee might increase post-exercise systolic blood pressure. The impact of coffee consumption on pulse pressure recovery after rest following a night shift should be further investigated.Regular coffee consumption increases BDNF expression in the in the mouse hippocampus53, the impact of shift work on mental health has been reported to differ between genders54. Therefore, our findings in female nurses cannot be applied men. In addition, our findings cannot be applied to postmenopausal women since a lower circulating BDNF concentration has been observed in postmenopausal females than in young females56. Second, menstrual cycle information was not recorded for analysis in the present study. An increase in circulating BDNF during the luteal phase compared with the follicular phase has been reported in woman with normal menstrual cycles57. Additionally, Dunne et al.58 reported lower blood pressure during the luteal phase than during the in follicular phase, and Mills et al.59 reported a difference in blood-pressure recovery after stress between the luteal phase and follicular phase. Therefore, the menstrual cycle could be a confounding factor in studies of young females. Third, we did not measure the serum BDNF levels when blood pressure was assessed because of the relationship between BDNF and vascular functions consistently reported in previous studies62. Fourth, the change in diastolic blood pressure was not statistically significant after rest. We did not further examine the underlying causes of differences in recovery between systolic and diastolic blood pressures. Finally, we did not explore the mechanism linking BDNF and pulse-pressure recovery after night shift work; moreover, we did not assess the long-term cardiovascular outcomes in subjects with high pulse pressures after a one-hour rest period.We collected serum BDNF data in the morning after a night shift when the participants had worked the night shift for three weeks, and we measured the morning blood pressure after a night shift in female nurses who had rotated to a new series of night shifts within one week of the rotation. We found that high morning serum BDNF levels during stable night shift work could predict the quick recovery of a widening pulse pressure after a one-hour rest in the female nurses who were beginning a new night-shift schedule. However, the present study had certain limitations. First, the study only included young female nurses. Despite the delayed recovery of blood pressure in men performing night shift workIn conclusion, the serum BDNF concentration measured during a stable period of night shift work predicted a reduction in pulse pressure in female nurses after one hour of rest when they were rotating to a new period of night shifts. These findings may indicate a possible modulatory effect of circulating BDNF on the recovery of pulse pressure in female nurses after they have worked rotating night shifts. Further studies are necessary to investigate the underlying mechanisms linking serum BDNF during night shift work to the long-term cardiovascular prognosis.


Sickle cell disease (SCD) is the most common inherited disorder worldwide, with the highest burden in sub-Saharan Africa. The natural history of SCD is characterized by periods of steady state interspersed by acute episodes. The acute anemic crises may be transient and are precipitated by treatable factors like infections, nutritional deficiencies, and sequestration. Anemia is almost always present, although it occurs at different levels of severity.This paper describes the protocol of a cross-sectional study to determine the prevalence of severe anemia and associated factors among sickle cell patients hospitalized at the Muhimbili National Hospital.t-test will be used for numerical variables. Regression models for severe anemia against explanatory and confounding variables will be run, and results will be presented as adjusted odds ratio with 95% confidence intervals. A P value of <.05 will be considered significant.This is an ongoing, descriptive, cross-sectional, hospital-based study among individuals with SCD, admitted to the Muhimbili National Hospital in Dares Salaam, Tanzania. A minimum sample size of 369 was calculated based on the previous prevalence of hospitalizations due to severe anemia (20%) in the same cohort. We are using a piloted standardized case report form to document clinical and laboratory parameters following informed consent. Data analysis will be performed using Stata software. Severe anemia is defined as Hb<5g/dL. Chi-square or Fisher’s exact test will be used to ascertain association between categorical variables, and Enrolment commenced in January 2015 and concluded in September 2016. Complete data analysis will begin in February 2018. The study results are expected to be published in May 2018.This protocol paper will provide a useful and practical model for conducting cross-sectional studies in hospitalized patients that cover a wide ranging of clinical and laboratory variables. Sickle cell disease (SCD) is the most common inherited disorder worldwide with the highest burden in sub-Saharan Africa . It is ap=.001]) has been shown to be an independent predictor of death [Anemia is a condition in which the number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body’s physiological needs. These needs vary with a person’s age, sex, residential elevation above sea level , smoking behavior, and different stages of pregnancy . The Worof death . Similarof death .The major contributors of severe anemia in SCD in Africa are not known. Studies on African children on this topic have reported an association with bacteraemia, malaria, hookworm, HIV, as well as deficiency in vitamins A, B12 and glucose-6-phosphatase dehydrogenase -11,12. NBlood transfusion is almost always used to manage severe anemia in SCD . There aAlthough the burden and factors associated with severe anemia have been described in children and pregnant women in sub-Saharan Africa ,11,30,31This is a hospital-based, descriptive, cross-sectional study among SCD individuals hospitalized at the Muhimbili National Hospital (MNH). MNH is the national referral hospital in collaboration with Muhimbili University of Health and Allied Sciences, which is the oldest and largest biomedical university in Tanzania. Muhimbili is located in Dar es Salaam on the eastern coast of Tanzania.The study population consists of individuals with SCD who are already registered in the Muhimbili Sickle Cohort (MSC) and are hospitalized at MNH. The MSC has enrolled 5430 individuals with SCD between 2004 and March 2016. Of these 51.5% and 48.5% are male and female, respectively. The majority (65%) are below the age of 18 years. In this study, we enrolled hospitalized patients who consented and fulfilled inclusion criteria during the 21-monthstudy period (January 2015 to September 2016).The sample size for this study was estimated to be 369 patients and it was based on the finite population of 800 SCD cases . This sample has a power of 80% to detect the prevalence of severe anemia of 20% with a 4% margin of error and confidence interval of 95%.The following inclusion and exclusion criteria were used:Inclusion criteriaConfirmed SCD; HbSS by High Performance Liquid Chromatography or Hemoglobin ElectrophoresisEnrolled in the MSCHospitalization at MNH during the study periodExclusion criteriaIndividuals on hydroxyureaBlood transfusion in the past 4 weeksReadmission within the past 4 weeksThe enrolment procedure is illustrated in A general examination was performed that included a record of temperature, weight, blood pressure, peripheral oxygen saturation, pulse, and respiratory rate. Detailed clinical history and physical examination were undertaken to determine the events leading to hospitalization. The study procedures were explained to the patients as well. Details of tests to be performed and samples needed were given to the patients by the study clinician. HIV pretesting counseling was done to all eligible patients. Consent was sought after all the information had been given to the patients.Confirmed SCD individuals admitted and enrolled were managed according to the standardized guidelines on the management of SCD. Additional investigations were requested depending on clinical indications. Clinical outcomes and laboratory results  of everyTen milliliters of blood was collected from all participants under aseptic technique. Of these, 2 mL of blood was collected in a tube with ethylenediamine tetraacetic acid (EDTA) anticoagulant, 2 red tops (serum separator) were filled with 2 mL of blood each, and 4 mL was taken for blood culture. Samples for blood culture were collected in commercially prepared BacTec bottles. In addition, stool and urine samples were collected in empty sterile bottles. All samples were labelled with patients' name, SCD identification number and a special ID number created for the purposes of this study.Of the EDTA sample, 5µl was used to perform a malaria rapid test (RDT). The remaining sample was used to perform a full blood count. This includes a peripheral blood cell count, both total and differential white cell count, as well as red blood cell indices. These tests were performed immediately after sample collection.For the serum separated samples, clinical chemistry analysis as well as micronutrient analysis  were performed on the batched serum samples after enrolment had concluded.Venous blood in a EDTA tube or capillary blood sample via puncture of a finger was required for the malaria test. The malaria device Pf (HRP2) Ag RDT was used and 5µl of blood was applied to the sample using a pipette or micropipette. 60 µl of assay buffer solution (2 drops of the bottle type) was put into the A well. Results were read in 20 minutes. Correction for white cell count was conducted for counting parasite density in thick films. If the test could not be performed immediately, the blood was stored at 2-8˚C for 3 days. All test components were performed at room temperature.Quality control was used to assure that the malaria Pf cassette test was working properly and that the results being generated are correct. If no lines were visible, or if no control line (C) formed, whether or not a sample line (T) appeared, the assay was deemed invalid and was repeated with a new sample and cassette.Thick films for malaria diagnosis was prepared from the blood sample at the time of collection or from the EDTA bottle in the laboratory.Outcome variable: hemoglobin levels Independent variablesSociodemographic characteristicsEthnicityResidencyAge as continuous and as categorical variable (<18 or ≥18 years)Sex Symptoms and signsPallor Jaundice , if yes 2 saturation-continuous, hypoxia OEnlarged spleen , size (continuous)Enlarged liver , size (continuous)Past medical historyAdmissions in the past 12 months , frequency Blood transfusion in the past 12 months , frequency (continuous), units (continuous)Pain in the past 12 months , frequency (continuous)Stroke in the past 12 months History of heart failure Laboratory variables ; see Hematological: full blood count and reticulocyte countParasitology: malaria and hookwormMicrobiology: bacteraemia and HIV infectionBiochemistry: liver and renal function tests, lactate dehydrogenase, C reactive protein, serum folate, vitamin B12, vitamin A and serum iron studiesThick films were stained using Giemsa staining and examined by microscopy for the presence of malaria parasites using standard methods. The number of parasites (trophozoites) was counted against 200 white blood cells. A slide was reported negative for malaria parasites after at least 100 high-powered microscopic fields were examined. Counting malaria parasites against 200 white blood cells may have resulted in underestimating malaria density as the white cell count in SCD patients tends to be higher due to inflammation and hematology analyzers counting nucleated red blood cells as neutrophils and small lymphocytes. Therefore, ideally, the white cell count should be corrected and “normal” reference values for SCD and non-SCD individuals be calculated and used..The quality assurance process involved the following: all positive slides were read by a second person. If there were discrepancies between the two readings, then a third person was asked to intervene. For the negative slides, one out of every ten slides was read by a second person .Fresh stool was collected in a clean container to test for hookworm infection. A portion of fresh stool was taken with a spatula or wooden applicator and placed in a test tube, and then the test tube was filled with normal saline. The mixture was mixed well and centrifuged for 5 min at 3000 rpm . The supernatant was discarded and with help of a Pasteur pipette, the deposit (stool) was extracted and a small drop was placed on a slide. The deposit on the slide was covered by the cover slip and immediately observed for the hookworm ova under the microscope at 10x magnification. The counting was performed 20 minutes after collection. This method allows for other egg species to be identified We ensured that samples were collected in a clean container so as to avoid any false positive results. A picture of hookworm ova was available to make sure of correct diagnosis.The Sysmex XT2000i–Hematology automated analyzer was used to obtain the full blood count. The machine gives a wide range of hematological indices such as white blood cell count, reticulocyte count, hemoglobin levels and platelet count. 2µl of nonclotted venous blood was collected in EDTA tubes (purple caps). The samples were arranged on the roller mixer ready to be tested. Alternatively, the sample was inverted gently end to end (approximately eight times) until the cell bottom of the tube was completely suspended.On the standard tools bar, the manual section was selected, the patient details were entered and the enter button was pressed. Then the sample vial was held to the needle in front of the start button, and the start button pressed. Once the analysis was done, the results were printed out and reviewed for any panic values, which were then reported to the clinician immediately. If the differential values were missing from the printed results, the sample was diluted in a ratio of 1:5 using the cell pack reagent and the percentage values obtained. After the sample had been analyzed, plasma and buffy coat were obtained and stored under –20°C. This was achieved by centrifuging the EDTA blood at 3000 rpm for 10 minutes, thereafter separating the plasma and buffy coat in graduated cryo-preservative tubes.The controls for Sysmex machine XT2000i were commercially prepared reagents in 3bottles. Tube one contained low ranges of the hematological indices, tube two for normal and tube three for high hematological values. The quality control procedure was performed before running the samples. The controls needed to be at room temperature before the quality control procedure. The sampler mode from the main menu screen was selected and the tubes were arranged on the sample loader tray with their barcode facing the red barcode light. Then the start button was clicked for the analyzer to start analyzing the controls. Once done, one researcher ensured that the controls had been run on the analyzer and that they were within the acceptable limits.Architect Kits was used for aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine, lactate dehydrogenase (LDH), vitamin B12, folate and C reactive protein (CRP). The Retinol Kit was used for retinol binding protein (vitamin A). The analyzer used was Architect Ci 4100, which includes the chemistry analyzer C4000  and the immunoassay analyzer i1000SR (for vitamin B12 and folate). Our samples were stored at –80ºC for a maximum of 90 days.The batched samples that have been collected throughout the study period will be assayed using a chemistry analyzer  for the following parameters: bilirubin ; LDH), iron studies , CRP, folate, AST, ALT, vitamin A (retinol) and vitamin B12. Quality assurance was done using commercially prepared reagents that are run on a daily basis with the readings documented following laboratory protocol.Blood cultures were processed using standard hospital laboratory procedures. Culture media were prepared in a microbiological laboratory and identification followed conventional techniques.Samples were drawn from patients, stored in the BacTec blood culture bottles, and inserted directly into the instrument as soon as possible to ensure performance efficacy. Before placing vials into the instrument, barcodes were scanned and placed in their assigned stations through the vial entry activity. When scanning barcodes, the vial was placed in the alignment block in front of the scanner with the barcode label facing the scanner. The vial was rotated slightly so that the scanner could read the label. A single beep indicated a successful (good) scan. Station assignments were calculated by the system software to balance the rotor. In order to maintain rotor balance, vials were introduced and placed where the system indicated.The vial was carefully pushed into the station. In order to ensure that the vial was fully seated in the station, the shoulders were pressed. The vials were not twisted or turned once they were placed in the stations. Vials were not removed except in the following conditions:Removal of positiveRemoval of negativeIdentification of anonymous vialsWhen microorganisms are present, they metabolize nutrients in the culture medium, releasing carbon dioxide, which reacts with a dye in the sensor. The dye modulates the amount of light that is absorbed by a fluorescent material in the sensor. The instrument’s photo detectors then measure the level of fluorescence, which corresponds to the amount of carbon dioxide released by any micro-organisms present. This measurement is interpreted by the system in accordance with the preprogrammed positivity parameters.Many positive cultures were detected in the first 24 hours after inoculation. Subculturing the positive cultures was done in blood agar, chocolate agar, MacConkey agar, and in other culture media as appropriate. Gram staining was performed for each positive vial. Preliminary antimicrobial susceptibility and identification procedures were performed from fluid in the culture vials.Ongoing negative vials were kept for 7 days before being discarded as negatives.Serum/whole blood samples were used for this test. The samples were centrifuged at 3000 rpm for 10 minutes. Thereafter, the serum was graduated 1.25 mL tubes for the HIV test. With whole blood samples, the blood was directly tested for HIV test. The test was performed according to the Tanzania National HIV Rapid Test Algorithm.All clinical and laboratory information was collected using a preformatted CRF that was designed specifically for this study. This was piloted for a period of 2 weeks and adjusted accordingly. The CRF was reviewed weekly for the first month of data collection to amend variables and improve the quality of data collected. Tools for collecting anthropometric measurements and vital signs were calibrated according to manufacturer’s specifications. All data will be linked to the MSC database, a Web-based system known as MySQL .Laboratory data is being collected from different sources. For hematology data, the results were printed from hematology analyzers. Results generated from all laboratories were photocopied and the copies were added to the patient’s case notes. The original copies of results were attached to the corresponding CRFs.Data verification and cleaning is ongoing following double entry, and inconsistencies are being corrected. Missing data, not obtained during the data collection period, will be collected during subsequent visits or by telephone.The CRFs are stored in filing cabinets and locked, with access only to personnel involved in the study and to a few key personnel who are authorized by the principal investigator. Data backup is done on a daily basis onto 2 storage devices and stored in 2 different physical locations.Data is double entered and validated in a software application developed using MySQL database and PHP, a server-side HTML scripting language.t-test or analysis of variance. These will be adjusted for age and sex. Logistic and linear regression models will be used in assessment of the risk factors for severe anemia for the binary and continuous variables, respectively, as well as for controlling for confounders.Descriptive statistics will be summarized using cross-tabulation and frequencies for categorical data. For continuous variables, measures of central tendencies will be used after checking for normality and transformation where necessary. All estimates will be presented with 95% confidence intervals. Proportions will be compared using Chi-square test of Fisher’s exact test for categorical variables, while continuous variables will be compared using p value <.10 will be included in the multivariate models. Linear and nonlinear relationship between response and explanatory variables as well as the interaction between the explanatory variables and how these change in relation to age groups and sex , will be explored during model fitting. Both forward and backward elimination methods will be used to decide which variables remain in the minimal model based on the likelihood ratio test. We will produce a single, final model combining both laboratory and clinical variables as this will be the best model predicting severe anemia. Data analysis will be performed using Stata software (version 11) and R (version 3.3.2).Modelling procedures will start with the univariate models where the response variable will be fitted against each explanatory variable. Only sets of explanatory variables with a p values look like after analysis. We will decide which clinical and laboratory variables are most important and should be included; these may be the most important factors from literature and/or have enough participants in comparison groups to allow for reasonable comparison.For univariate and multivariate analyses, it will depend on how the Ethical clearance to conduct the study has been obtained from the Muhimbili University of Health and Allied Sciences and Research and Publication Ethical Committee. A formal written informed consent in Swahili was used for eligible individuals. Nonconsenting patients and those who were not eligible for the study were attended to by the clinical team per SCD management guidelines. Personal, clinical and laboratory information is being kept with utmost confidentiality in keeping with the standards and procedures guiding the organization.Enrolment commenced in January 2015 and concluded in September 2016. During the study period, 513 SCD individuals were hospitalized, of these 387 (72.8%) fulfilled inclusion criteria and were enrolled. Final results of batched laboratory tests are expected in January 2018. Data analysis is expected to be done in February 2018. The study results will be published in a peer-reviewed journal.Severe anemia is the most common cause of SCD morbidity and mortality in Tanzania. Although the clinical and laboratory factors associated with severe anemia have been described in the general population of sub-Saharan Africa ,11,26,27Currently available data in the literature list possible causes of severe anemia in SCD cases. These include infections like malaria, bacteraemia and HIV infections as well as hookworm infestation -12,18. OThis protocol describes in detail participant enrolment, and clinical and laboratory procedures. The study involved collecting multiple clinical and laboratory variables during the hospitalization period. No data was collected outside the hospitalization period. Drawing from 12 years' experience in clinical longitudinal surveillance, this protocol will contribute significantly to building a basis for a single-center, multivariable clinical study. It will also contribute towards harmonized inpatient clinical and laboratory procedures. The methodology will ensure the validity and reliability of data on the prevalence of severe anemia and associated factors in hospitalized SCD individuals.This study has several limitations. First, its cross-sectional design precludes us from establishing a cause-effect relationship. There is also potential for patient recall bias, especially in establishing past medical history. In this instance patients were asked to recall events from 12 months prior to hospitalization. Second, although interventions, like the use of antibiotics and/or antimalarial drugs in the days prior to admission were recorded, we have no certain way of knowing if the information provided is accurate. MNH is a national referral hospital; most patients are referred from peripheral facilities where they would have received interventions. Third, in this study, we are using 3 different laboratories to carry out various tests. Although the standard operating procedures for laboratory procedures are present and enforced, we cannot entirely eliminate human errors. Fourth, by the fact that MNH is a tertiary institution, there is a simple selection bias. This methodology paper will provide a useful and practical model for conducting inpatient clinical cross-sectional studies that cover a wide range of clinical and laboratory variables. The results of this study will be published in a peer-reviewed journal and have a potential to guide the management of severe anemia in SCD in order to reduce associated morbidity and mortality.


Clinical diagnosis of occlusal dysesthesia (OD), also referred to as phantom bite syndrome, is currently based on the absence of objective occlusal discrepancy despite the persistent complaint of uncomfortable bite sensation. We previously demonstrated that the subjective feeling of occlusal discomfort generated by artificial occlusal interference can be objectively evaluated using prefrontal hemodynamic activity in young healthy individuals. The aim of this study was to investigate whether dental patients with and without OD show distinct prefrontal activity during grinding behavior with an occlusal interference. Six dental patients with OD (OD group) and eight patients without OD (control group) grinded piled occlusal strips placed between their first molars and reported their perception and discomfort thresholds during continuous monitoring of prefrontal hemodynamic activity with a portable functional near‐infrared spectroscopy. Although patients without OD showed the typical hemodynamic pattern of increased oxyhemoglobin and reduced deoxyhemoglobin (HHb) concentration, those with OD showed persistent incremental increases of HHb concentration that began at the loading of occlusal strips on their molars before they executed grinding. The intensities of the task‐related HHb activities showed statistically significant differences between OD and control groups, particularly at channel 3, arranged over the left frontal pole cortex. When the discrimination criterion was set using the intensity values of channel 3 from both groups, the overall accuracy of the OD discrimination was 92.9%. Although physiological interpretation has yet to be elucidated, the task‐related response of an increase in HHb may be a useful neuronal signature to characterize dental patients with OD. Occlusal dysesthesia (OD)  and eight age‐matched dental patients without OD  participated in the experiment. Mean patient age and gender distribution conformed to those in a previous report of 37 cases  , and discomfort thresholds were 79.5 ± 9.6 and 76.0 ± 19.5 µm in control and OD groups, respectively (P = 0.865). There were no statistically significant differences in mean discrimination and discomfort thresholds between participant groups.Control and OD groups showed comparable occlusal vertical dimensions at perception and discomfort thresholds. Discrimination thresholds were 40.5 ± 6.0 and 32.0 ± 8.0 µm in control and OD groups (HRF(t) was defined from the loading of occlusal strips  and 4  and deoxyhemoglobin (HHb) concentration change responses in conditions without bite rise, with occlusal vertical dimension at perception, and with that at discomfort threshold were shown in Figure We calculated threshold values to discriminate the occurrence of OD using the regression coefficient values of channel 3, showing the highest statistical significance in group comparison. After determining the threshold value in each test and training data sets in the leave‐one‐out cross‐validation, the mean classification accuracy was 92.9%. The overall sensitivity, specificity, positive predictive value, and negative predictive values were 83.3%, 100%, 100%, and 88.9%, respectively.We measured prefrontal hemodynamic responses during grinding behavior with slight occlusal interference in dental patients with and without OD. Patients with OD showed a task‐related increase in HHb; however, those without OD showed a task‐related reduction in HHb. This suggests that prefrontal hemodynamic responses may be a potential marker for detecting patients with OD. In addition to high discrimination accuracy of OD patients in the regression analysis of HHb responses, this examination requires minimal stress to the patient, because the thickness of the occlusal interference does not exceed the individual discomfort threshold and the portable fNIRS system enables the patient to remain in the dental chair during examination. In addition to the previous studies  suggesting that this response is associated with top‐down cognitive control, preparing for the upcoming examination of occlusal vertical dimension, as opposed to bottom‐up perception processing based on ongoing motor/proprioceptive afferent information. The potential contamination of the motion artifact and the autonomic change in the cutaneous blood flow can be excluded because cortical HbO and HHb behaved differently, and the time course of the cutaneous blood flow response differed from those of the cortical. Alongside the fact that the HHb responses are less affected by systemic responses, such as breathing cycles and blood pressure changes (Kirilina et al., We observed a distinct pattern of HbO and HHb responses during the grinding task between patients with and without OD. Corresponding to our previous fNIRS study applying a similar bite rise paradigm to healthy young adult volunteers (Ono et al., The time course of the hemodynamic responses at discomfort threshold tended to show larger amplitudes compared with those in the other conditions in both participant groups, although the peak amplitudes were not statistically different among the conditions Fig. . The disIn addition to the averaged hemodynamic responses obtained through all bite rise conditions, we also examined discrimination accuracy using regression coefficient values from hemodynamic responses in the individual trial at no bite rise, discrimination threshold, and discomfort threshold. The best discrimination accuracy was obtained when we utilized the averaged hemodynamic responses. This suggests that averaging responses may be useful to suppress artifacts that are not time‐locked with the grinding task.There were several limitations to the current study. First, the sample size was small because of the relatively rare occurrence of OD. Accumulating more cases could help determine the general diagnostic criteria of OD via intensity of task‐dependent HHb responses. Second, measured cortical areas were limited to the anterior prefrontal region. The portable fNIRS system utilizes light‐emitting diodes as a light source, and therefore, we were unable to detect signals from cortical areas covered with hair, such as somatosensory cortices and DLPFCs, because of the absorption of near‐infrared light by black hair and hair roots in the Asian participants. Whole‐head fNIRS imaging using a system equipped with high‐power laser diodes as a light source should be utilized to investigate whether the increased HHb response in the FPC is associated with reallocation of blood flow. However, the FPC activity well characterized dental patients with and without OD and is therefore potentially useful for OD diagnosis. The comparable perception and discomfort thresholds between patients with and without OD found in the current study support a previous report (Baba et al., In conclusion, we propose a regression analysis of fNIRS signals during grinding behavior to diagnose OD. Our results suggest that HHb response coefficients from the left FPC are significantly different between patients with and without OD and are therefore potentially useful to discriminate the occurrence of OD.None declared.


Obesity, systemic arterial hypertension (SAH) and obstructive sleep apnea(OSA) are closely related. Up to 70% of patients with OSA may beasymptomatic, and there is evidence that these patients have cardiovasculardisease, especially nocturnal SAH.The aim of this study was to evaluate 24-hour blood pressure circadianvariation in asymptomatic, obese individuals with moderate-to-severe OSA andcompare it with that in individuals with mild OSA or without OSA.2), with casual blood pressure < 140/90 mmHg andwithout comorbidities were recruited. Eighty-one patients underwent clinicaland anthropometric assessment, ambulatory blood pressure monitoring (ABPM),and Watch-PAT. Participants were divided into two groups, based on theapnea-hypopnea index (AHI): group 1, with AHI < 15 events/hour, and group2 with AHI ≥ 15 events/hour.Eighty-six obese subjects aged between 30 and 55 years , highersystolic and diastolic blood pressure measured by the 24-h ABPM , and higher nocturnal diastolicpressure load .Moreover, there was a positive correlation between nocturnal diastolic bloodpressure and AHI .Asymptomatic obese subjects with moderate-to-severe OSA have higher systolicand diastolic blood pressure at 24 hours compared with those with absent /mild OSA, despite normal casual blood pressure between the groups. Theseresults indicate that ABPM may be useful in the evaluation of asymptomaticobese patients with moderate-to-severe OSA. However, according to theclassic study Sleep Health Study, many OSA patients are asymptomatic, as 70% ofpatients with mild apnea and 9% of those with severe apnea wereasymptomatic.6A recent systematic review estimated that the prevalence of OSA is higher among men,and ranges from 9 and 38% in the general population.2 Obese patients have higherprevalence of OSA and SAH7 and theassociation of obesity with SAH may cause target-organ injury and cardiovascularevents.9 Studies have demonstrated that OSA patients haveless nocturnal blood pressure (BP) dipping and nocturnal hypertension.11 Most of these reports have included hypertensive patientswith previous diagnosis of OSA. A previous study suggested a higher prevalence ofmasked hypertension (MH) in patients with OSA.8 However, little is known about the 24-hour BP behavior inobese individuals with OSA and normal casual BP. The aim of this study was to assess24-hour BP circadian variation in obese, asymptomatic subjects withmoderate-to-severe OSA compared with subjects with mild OSA or without OSA.OSA is mostly related to obesity and systemic arterial hypertension (SAH).2, normal casual BP (BP < 140/90 mmHg), and absence ofcomorbidities, and regular follow-up. Exclusion criteria were history ofarterial hypertension or treatment for this condition, diabetes mellitus,pulmonary disease, Parkinson disease, previous therapy with continuous positiveairway pressure (CPAP), and previous diagnosis of OSA.In the period from January to December 2014, individuals attending the internalmedicine outpatient clinic of Piquet Carneiro Polyclinic of Rio de Janeiro StateUniversity (UERJ) were invited to participate in the study. Inclusion criteriawere age between 30 and 55 years, body mass index (BMI) between 30 and 39.9kg/mPlataformaBrasil/CAAE: 03489612.1.0000.52590), and informed consent wasobtained from all participants.The study was approved by the local ethics committee was performed, with a maximum interval of one-week between the visits.12 Height was measured using the vertical rod attached tothe same scale, with patients standing straight and heels together. Body massindex (BMI) was then calculated, by dividing body weight (kg) by height(m2). Circumferences were measured using an inextensible,graduated measuring tape.13Neck circumference (NC) was at the level of cricoid cartilage; waistcircumference (WC) was measured at the midpoint between the lower rib and theiliac crest at the end of expiratory phase of respiration. Hip circumference wasmeasured at the femoral trochanters.14 All measures were taken in cm and at the nearest 0.5cm.Body weight was measured with participants standing at the center of theplatform, wearing light clothes and barefoot, using a Filizola® digitalscale with maximum capacity of 180 kg.15 Beforethe measurement, participants remained seated for 30 minutes and refrained fromcoffee and smoking. Three measurements were taken with a one-minute intervalbetween them, and the mean of these three measurements was defined as casualBP.Casual BP was measured using an electronic device  and a cuff with adequate size, according topatient’s arm circumference, following the Brazilian Guidelines onHypertension.Venous blood samples were collected after an overnight fasting (12 hours) fordetermination of total cholesterol, HDL-cholesterol, triglycerides and glucoselevels. HDL-cholesterol levels were calculated by the Friedewald formula.16 Watch-PAT provides an algorithm able todifferentiate between sleep and awake state every 30 seconds, and to calculatethe respiratory disturbance index (RDI) using the total sleep time rather thanthe total recording time at rest. The actigraphy algorithm provides an accuratemeasure of sleep and wake states in normal subjects and patients with OSA. Thissimple method for evaluation of sleep total time is a useful tool to accuratelyquantify OSA in the home environment.17The diagnosis of OSA was determined by a home, portable monitoring device, theWatch-PAT, which indirectly detects apnea-hypopnea events by identifyingsympathetic activities related to these events. After the test, results areautomatically read and analyzed by a computer program.18 Theanalysis algorithm uses four functions to detect different parameters includingthe apnea-hypopnea index (AHI), RDI, oxygen desaturation index (ODI), theminimum, mean and maximum oxygen saturation and sleep stages.16The American Academy of Sleep Medicine recognizes the Watch-PAT device as auseful alternative for the diagnosis of OSA, since it allows a manual orautomatic edition of the scores obtained. Besides, there are not many technicalfailures with the use of the Watch-PAT at home.Patients were divided into two groups based on the AHI: group 1 with an AHI <15 events/hour and group 2 with an AHI ≥ 15 events/hour, aiming toseparate patients with moderate/severe OSA (group 2) from those without OSA (AHI< 5 events/hour) or mild OSA (AHI = 5-14 events/hour).19 Thereadings were taken every 20 minutes during the day and every 30 minutes atnight. During the monitoring period, subjects recorded the awake and sleepperiods to calculate mean BP during these periods. Patients were instructed toavoid sleeping for more than one hour during the day. The ABPM was consideredadequate if 70% of the measures were successfully obtained. The percentage ofnocturnal BP decrease for systolic and diastolic pressures was calculated as themean of diurnal BP minus the mean nocturnal BP, multiplied by 100 and divided bythe mean diurnal BP. BP load was considered abnormal when more than 30% of thevalid BP readings in the ABPM were above the normal limits. MH was defined as acasual BP lower than 140/90 mmHg and 24-hour BP higher than 130/80 mmHg in theABPM, and/or awake BP greater than 135/85 mmHg and or sleep BP greater than120/70 mmHg.11Twenty-four-hour ABPM was performed using the Spacelabs 90207 monitor . The cuff, with a size appropriate for the patient’s armcircumference, was placed on the non-dominant upper-arm. This monitor isvalidated by the British Hypertension Society and by the Brazilian Society ofCardiology.2) and expressed as percentage offrequency distribution. Correlations were assessed by the Pearson correlationtest. Sample size was estimated based on previous studies on 24-hour systolic BPin similar populations.9Assuming a level of significance of 5% and a standard deviation of 8 mmHg, 23patients in each group would have a power of 80% to detect a difference of 5mmHg in 24-hour systolic BP between the groups.Data were analyzed by the Statistical Package for Social Sciences (SPSS) version18.0 , and the results expressed as mean ±standard deviation. Continuous variable showed a normal distribution accordingto the Kolmogorov-Smirnov test. The unpaired Student's t test was used tocompare the mean between the groups. Categorical variables were compared usingthe chi-square test , and group 2 was composed of 26 (32%) individuals.A total of 86 participants were selected. However, 3 patients had arterialhypertension during the first visit, and 2 subjects refused to perform the ABPM.Therefore, full examination was performed in 81 patients. Mean age was 42 ± 6years, and mean BMI was 33.8 ± 3.0 kg/mDespite similar mean age in both groups, male sex was predominant in group 2 . Also, aSystolic and diastolic casual BPs were similar between the groups. Nevertheless,group 2 had higher diurnal and nocturnal BP levels in the ABPM, and higher nocturnaldiastolic BP load . Also in20The findings of the present study showed that asymptomatic, obese subjects withmoderate/severe OSA had higher 24-hour BP than subjects without OSA and/or with mildOSA. In addition, nocturnal diastolic BP was correlated with AHI. The mainmechanisms of increased BP in patients with OSA are increased sympathetic activity,renin-angiotensin system dysfunction, endothelial dysfunction, hypoxemia, anddisruption of normal sleep. These changes lead to increased peripheral vascularresistance and a predominantly diastolic hypertension.7 In the presentstudy, the percentage of patients with moderate/severe OSA was similar to thosereported in previous reports.23 In the Wisconsin study,approximately 9% of men and 4% of women aged between 30 and 60 years had AHI≥ 15 events/hour.24 In asimilar study, approximately 13% of men and 9% of women had moderate/severe OSA (AHI≥ 15 events/hour).25 Inthis study, we also observed a higher number of men than women in the group ofmoderate/severe OSA.26In obese individuals, the prevalence of OSA is higher than in non-obesesubjects.28 in the SleepHeart Health Study,6 whichevaluated 6,120 individuals in a hospital population, BMI was an independent riskfactor for OSA, with an odds ratio of 1.55-1.60. In the present study, we did notfind an association between BMI and OSA, which may be explained by the small samplesize and narrower range of BMI for the inclusion criteria (BMI ≥ 40kg/m2 was excluded). Besides, increased visceral adiposity may bemore important in OSA physiopathology than overall obesity.The relationship between BMI and OSA is controversial. Although such correlation wasnot found in two previous studies,27Similar results were found in a study comparing individuals with different degree ofsnoring, indicating a significant difference in WHR between the groups.29The anthropometric parameters NC and WHR could be used to identify individuals athigh risk for OSA. In a study with 192 patients suspected of OSA, WHR was associatedwith moderate-to-severe OSA.30 In the present study, both NC andWHR were significantly higher in patients with moderate/severe OSA, despite similarBMI and WC between the groups. This finding corroborates previous studies,suggesting that both NC and WHR could be routinely assessed in obese outpatients, toidentify those patients at higher risk for OSA.With respect to NC, a study on 129 individuals suspected of OSA reported that thisanthropometric parameter was an independent risk factor for OSA.31 Besides, analysis of BP circadian rhythm by the ABPM mayreveal other prognostic information, such as increased prevalence of MH andincreased nocturnal BP. The identification of patients with MH is important in dailyclinical practice, since previous studies suggested that these patients have moretarget-organ injuries, including microalbuminuria and left ventricularhypertrophy.33 Furthermore, a meta-analysis ofseven studies and 11,502 patients reported that MH patients have twice the risk ofcardiovascular death than normal BP subjects.34 The prevalence of MH in the general population varies from16 to 24%.33 However, in OSApatients, these values may be even higher: two previous studies reported aprevalence of nearly 30% of MH in OSA patients.9 In accordance withthese studies, the present study showed a slightly higher percentage of MH in themoderate/severe OSA group.The current study also found that subjects with moderate-to-severe OSA had highersystolic and diastolic BP in the ABPM. According to cross-sectional studies on OSA,hypertension is more prevalent in OSA patients, even after controlling forconfounding factors, such as age and obesity.35 Increased nocturnal BP may be associated withincreased inflammatory markers, which may explain the increased risk forcardiovascular complications.36Previous studies have suggested a relationship between OSA and nocturnalhypertension. The authors suggest that increased adrenergic activity, hypoxemia, andsleep disruption could explain the increased nocturnal hypertension in patients withOSA.38 In the first study, 84% ofpatients with mild to moderate OSA were considered “non-dippers” .11 In the secondstudy, the authors observed nocturnal arterial hypertension and absence of nocturnalBP dipping in OSA patients, in addition to a significant correlation betweennocturnal arterial hypertension, absence of nocturnal dipping and AHI.39 In our study, higher values of BPin the ABPM, and increased nocturnal diastolic pressure load were found in patientswith moderate/severe OSA. Also, there was a correlation between nocturnal diastolicBP and AHI. However, no significant difference in nocturnal dipping was foundbetween the groups.Two studies showed a relationship between OSA and nocturnal diastolichypertension.40 Second, the higher prevalence of men in the group withhigher AHI may have influenced the anthropometric results. Third, the crosssectional design of the study does not allow us to conclude a causal relationshipbetween OSA and arterial hypertension. However, the use of ABPM permitted themeasurements of nocturnal BP, and the identification of MH and nocturnal arterialhypertension. This study has some limitations. First, OSA was diagnosed by a portable monitorrather than polissonography, which is the gold-standard diagnostic method.Nevertheless, studies on validation of the Watch-PAT equipment showed similarresults between measures taken by this system and those obtained bypolissonography.Asymptomatic obese individuals with moderate/severe OSA have higher 24-hour systolicand diastolic BP in comparison with those with absent/mild OSA, despite normalcasual BP. These results indicate that the ABPM may be useful in the assessment ofasymptomatic obese patients with moderate-to-severe OSA. Prospective studies areneeded to confirm this hypothesis.


P < 0.001), while there were no gender differences in the bias between PPV and SVV. The Nexfin monitor adequately reflects alterations in PPV and SVV during a provoked fluid shift, but the level of agreement between PPV and SVV was low. The SVV tended to be superior over PPV or Eadyn in predicting fluid responsiveness in our population.Nexfin beat-to-beat arterial blood pressure monitoring enables continuous assessment of hemodynamic indices like cardiac index (CI), pulse pressure variation (PPV) and stroke volume variation (SVV) in the perioperative setting. In this study we investigated whether Nexfin adequately reflects alterations in these hemodynamic parameters during a provoked fluid shift in anesthetized and mechanically ventilated patients. The study included 54 patients undergoing non-thoracic surgery with positive pressure mechanical ventilation. The provoked fluid shift comprised 15° Trendelenburg positioning, and fluid responsiveness was defined as a concomitant increase in stroke volume (SV) >10 %. Nexfin blood pressure measurements were performed during supine steady state, Trendelenburg and supine repositioning. Hemodynamic parameters included arterial blood pressure (MAP), CI, PPV and SVV. Trendelenburg positioning did not affect MAP or CI, but induced a decrease in PPV and SVV by 3.3 ± 2.8 and 3.4 ± 2.7 %, respectively. PPV and SVV returned back to baseline values after repositioning of the patient to baseline. Bland–Altman analysis of SVV and PPV showed a bias of −0.3 ± 3.0 % with limits of agreement ranging from −5.6 to 6.2 %. The SVV was more superior in predicting fluid responsiveness (AUC 0.728) than the PVV (AUC 0.636), respectively. The median bias between PPV and SVV was different for patients younger [−1.5 % (−3 to 0)] or older [+2 % (0–4.75)] than 55 years ( Pulse pressure variation (PPV) and stroke volume variation (SVV) are increasingly used to monitor hemodynamic changes and guide fluid management in non-cardiac surgery or during intensive care unit admission in mechanically ventilated patients , 2. In p® or CNAP-500®, facilitates monitoring of these indices in patients without an indication for an intra-arterial line , arterial systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure MAP, heart rate (HR), pulse pressure (PP), pulse pressure variation (PPV), stroke volume variation (SVV), stroke volume (SV) or cardiac index (CI), Patients were categorized according to age (<55 or ≥55 years) or gender. Dynamic arterial elastance  and lowest (PPmin) pulse pressure divided by the mean of PPmax and PPmin (PPV (%) = 100 × (PPmax − PPmin)/((PPmax + PPmin)/2)). Stroke volume variation (SVV) was defined as the relative variation between the highest (SVmax) and lowest (SVmin) stroke volume divided by the mean of SVmax and SVmin (SVV (%) = 100 × (SVmax − SVmin)/((SVmax + SVmin)/2)). Changes in hemodynamic parameters upon Trendelenburg positioning (TB start) when compared to steady state values were analyzed using a paired T test. The decrease in PPV and SVV upon Trendelenburg positioning was assessed using repeated measures ANOVA (RM).Nexfin CC data were extracted using Frame Inspector  and analyzed using SPSS Statistics version 17.0 . Results are expressed as mean ± SD or median with interquartile range. Mean hemodynamic values were calculated over a period of 30 s recorded during the initial steady state (baseline) and at four consecutive time frames of 15 s during the first minute in Trendelenburg position and in the neutral supine position following Trendelenburg. Pulse pressure variation (PPV) was defined as the relative variation between the highest  curve. The relative increase in stroke volume was determined from baseline values and the highest value during Trendelenburg positioning. The predictive value of PPV or SVV was expressed as the area under the curve (AUC) with 95 % confidence intervals. The AUC’s for the SVV and PPV were compared using the method described by DeLong et al. . A Mann–2. We observed no technical failure of the Nexfin device, and retrieved a non-invasive arterial blood pressure waveform in all included patients. After anesthesia induction and endotracheal intubation, baseline hemodynamic parameters estimated 98 ± 16 mmHg (SBP), 62 ± 9 mmHg (DBP), 76 ± 12 mmHg (MAP), 78 ± 13 beats per min (heart rate) and 3.1 ± 0.7 l m−2 min−1 (CI).The study included 54 patients  with an average age of 45 ± 16 years and body mass index of 25.5 ± 3.6 kg/mP < 0.001), and remained unaltered throughout the rest of the study period. Both pulse pressure variation  and stroke volume variation  significantly decreased upon Trendelenburg positioning , and returned to baseline values after repositioning to supine steady state. While Trendelenburg positioning slightly increased stroke volume  when compared to steady state values, cardiac index remained unaltered (panel F). The number of patients with a decrease in SVV or PPV of 3 % or more after 15° Trendelenburg positioning estimated 59 and 56 %, respectively. During Trendelenburg positioning, SVV and PPV decreased by 3.4 ± 2.7 and 3.3 ± 2.8 %, respectively.Trendelenburg positioning did not induce a change in mean arterial pressure Fig. , panel AP = 0.079). Fluid responsiveness was equally present in the group of patients with an Eadyn < 0.89 or Eadyn > 0.89 . Subdivision of patients according to Eadyn showed a slight improvement in the AUC for the predictive value of PPV and SVV for fluid responsiveness in subjects with an Eadyn < 0.89 .Overall, 11 out of 54 patients responded to the fluid challenge as defined by a minimal rise in stroke volume of 10 % during Trendelenburg positioning. The SVV and PPV decreased by 3.7 ± 3.0 and 3.8 ± 3.8 % in case of fluid responsiveness, and 3.3 ± 2.6 and 3.2 ± 2.6 % in patients who did not respond to a fluid challenge, respectively. Figure P < 0.001). The PPV–SVV difference was similar among male and female patients (panel B). There was a very small correlation between body surface area and the difference between PPV and SVV .Figure P < 0.001; repeated measures analysis). The Eadyn was further subdivided in values higher or lower than 0.89. In patients with a steady state Eadyn < 0.89 , the MAP and CI increased in 52.9 and 29.4 % of all subjects, respectively, after Trendelenburg positioning. For patients with an Eadyn ≥ 0.89 , the MAP and CI increased in 40.5 and 40.5 % of the cases, respectively, after Trendelenburg positioning.The dynamic arterial elastance expressed as the PPV/SVV ratio during Trendelenburg positioning and repositioning for patients younger and older than 55 years is shown in Fig. This study shows that the Nexfin non-invasive arterial blood pressure monitor reflects a mild provoked fluid shift after Trendelenburg positioning in mechanically ventilated patients by alterations in the pulse pressure variation (PPV) and stroke volume variation (SVV), while the mean arterial pressure (MAP) and cardiac index (CI) were not sensitive enough to reflect this fluid challenge. While PPV is directly derived from non-invasive arterial blood pressure measurements, the Nexfin SVV is calculated based on the Nexfin CO-trek algorithm, which requires input of patient demographics. The baseline SVV tended to be superior over PPV in predicting fluid responsiveness in our population. Our findings indicate that the PPV and SVV are of additional value to static indices for clinical determination of fluid shifts in anesthetized patients.In accordance to our study, Rex et al.  investigContinuous arterial blood pressure monitoring was used for evaluation of ventilation-induced changes in pulse pressure and stroke volume. While the PPV is directly derived from the blood pressure signal, evaluation of the SVV requires an additional algorithm based on pulse contour analysis from arterial blood pressure waveforms . It mighNexfin cardiac index values have proven to be unreliable in studies in critically ill patients, since they included patients with potentially confounding factors due to abnormal vascular tone, peripheral hypoperfusion due to septic shock, or cardiac stunning –26. The dyn can be used in the decision to administer fluids or vasopressors as previously suggested [dyn is different in younger and older subjects. These findings should be considered in light of the assumption that all included patients had a normal preload reserve, which is a prerequisite for Eadyn measurements. An adequate preload reserve is defined as a normal distensibility of the left ventricle, and is most likely to be normal in our study population that consisted of subjects without diabetes mellitus or cardiovascular diseases. Besides, the proposed Eadyn threshold for determination of blood pressure sensitivity to fluid loading seemed unreliable in the current population, although we have to emphasize that vasopressor effects were not evaluated in this study.We investigated whether the Eauggested . We howeWe used a tidal volume of 8 ml/kg or more, with a positive end expiratory pressure of 5 mmHg in patients with a closed thorax and without arrhythmias in order to reliably measure PPV and SVV . TrendelIn conclusion, we show that Nexfin PPV and SVV reflect changes in the filling state of the patient, and are more sensitive to these fluid changes than mean arterial pressure and cardiac index. In the context of its non-invasive nature, Nexfin may therefore be of clinical value during monitoring of patients subjected to intraoperative fluid shifts. However, there is an age-dependent difference in PPV and SVV, which may be of influence on the choice for the right dynamic indicator for fluid responsiveness.