Comparison of different near-infrared spectroscopic cerebral oxygenation indices with central venous and jugular venous oxygenation saturation in children

BACKGROUND: We compared two different near-infrared spectrophotometers: cerebral tissue oxygenation index (TOI) measured by NIRO 200 and regional cerebral oxygenation index (rSO(2)) measured by INVOS 5100 with venous oxygen saturation in the jugular bulb (SjO(2)) and central SvO(2) from the superior caval vein (SVC) during elective cardiac catheterization in children. METHODS: A prospective observational clinical study in 31 children with congenital heart defects in a catheterization laboratory was undertaken. TOI was compared with SjO(2) in the left jugular bulb and with SvO(2). rSO(2) was compared with SjO(2) from the right jugular bulb and SvO(2). Linear regression analysis and Pearson's correlation coefficient were calculated and Bland-Altman analyses were performed. RESULTS: Cerebral TOI and SjO(2) were significantly correlated (r = 0.56, P < 0.0001), as well as TOI and SvO(2) with r = 0.74 (P < 0.0001). Bland-Altman plots showed a mean bias of -4.3% with limits of agreement of 15.7% and -24.3% for TOI and SjO(2) and a mean bias of -4.9% with limits of agreement of 10.3% and -20.1% for TOI and SvO(2). Cerebral rSO(2) and SjO(2) showed a significant correlation (r = 0.83, P < 0.0001) and rSO(2) and SvO(2) showed excellent correlation with r = 0.93 (P < 0.0001). Bland-Altman plots showed a mean bias of -5.2% with limits of agreement of between 8.4% and -18.8% for rSO(2) and SjO(2) and a mean bias of 5.6% with limits of agreement of 13.4% and -2.2% for rSO(2) and SvO(2). CONCLUSIONS: Both near-infrared spectroscopy devices demonstrate a significant correlation with SjO(2) and SvO(2) values; nevertheless both devices demonstrate a substantial bias of the measurements to both SjO(2) and SvO(2).     

A comparison of the INVOS 4100 and the NIRO 300 near-infrared spectrophotometers

We determined whether two different devices for measuring near-infrared spectroscopy (NIRS)---the INVOS 4100 and the NIRO 300---produce similar cerebral oxygenation data during the CO(2) challenge test. Nineteen patients anesthetized with sevoflurane, 67% nitrous oxide in oxygen, and fentanyl were studied. A series of measurements of regional cerebral oxygen saturation (rSO(2)), measured by the INVOS 4100, and tissue oxygen index (TOI), measured by the NIRO 300, were performed in the following conditions: 1) normocapnia (PaCO(2), 35--45 mm Hg); 2) hypocapnia (PaCO(2), 25--35 mm Hg); 3) normocapnia; and 4) hypercapnia (PaCO(2), 45--55 mm Hg). Hemodynamic variables, including arterial blood gases and cerebral blood flow velocity, were measured at the same time with transcranial Doppler. The values and percentage changes of rSO(2) and TOI were compared by using regression analysis and Bland and Altman analysis. The rSO(2) showed a significant positive correlation with TOI (r = 0.58, P < 0.01). The percentage change of rSO(2) also showed a significant positive correlation with the percentage change of TOI during the CO(2) challenge (r = 0.85, P < 0.01). Bland and Altman analysis revealed a bias of -0.5% with 2 SD of 15.6% when comparing the rSO(2) value with the TOI value, and it showed a bias of -3.4% with 2 SD of 15.2% when comparing the percentage change of rSO(2) with the percentage change of TOI, indicating unacceptable disagreement of these data. These results indicate that cerebral oxygen saturation and its relative change during the CO(2) challenge may vary depending on the type of NIRS used. Because the measurement technique and algorithm were different in each device, we should carefully consider the clinical application of the values produced by NIRS. IMPLICATIONS: Near-infrared spectroscopy (NIRS) has been proposed as a noninvasive clinical method for assessing cerebral oxygenation. The acceptable reliability and validity of NIRS values have not been established despite their widespread use. The INVOS 4100 and the NIRO 300 can display cerebral oxygen saturation as regional cerebral oxygen saturation and tissue oxygenation index, but they produce differing results.     

Transcutaneously measured near-infrared spectroscopic liver tissue oxygenation does not correlate with hepatic venous oxygenation in children

PURPOSE: To compare transcutaneous near-infrared spectroscopic (NIRS) measured liver tissue oxygenation with hepatic vein oxygen saturation (SvhO2) in children undergoing cardiac catheterization. METHODS: A NIRS optode (containing an emitter and a receiver of near-infrared light) was placed directly below the right costal arch above the palpable liver in 40 children aged 0.02 to 7.28 yr (median: 1.8 yr). Spatially resolved spectroscopic measured tissue oxygenation index (TOI) was recorded using the NIRO-300. Paired blood samples from the hepatic vein were taken under radiological control for determination of SvhO2 in a co-oxymeter. TOI values were compared with hepatic vein oxygenation, with simultaneously obtained arterial oxygen saturation (SaO2), inferior vena cava SO2 and hemoglobin concentration using simple linear and multi-regression analysis. RESULTS: TOI values ranged from 35% to 73% (58.6 +/- 8.4%); SvhO2 from 32% to 80% (58.4 +/- 14.4%), and arterial SO2 from 54% to 100% (90.0 +/- 11.4%). TOI and hepatic vein oxygen saturation failed to correlate (r = 0.052/P = 0.752). A regression model containing arterial saturation (Delta R2 = 0.177) and the ratio of pulmonary to systemic resistance (Delta R2 = 0.095) explained 27.3% of the observed variance in TOI. In this model, hepatic vein oxygen saturation was no longer significant; explaining only 3.4% of the variance. No other variable retained a significant association. CONCLUSION: Transcutaneously measured NIRS tissue oxygenation with an optode placed over the palpable liver does not correlate with SvhO2. The value is dominated by non-hepatic variables such as arterial saturation and vascular resistances.     

Cerebral near-infrared spectroscopy in adult patients after cardiac surgery is not useful for monitoring absolute values but may reflect trends in venous oxygenation under clinical conditions

OBJECTIVE: Cerebral near-infrared spectroscopy (NIRS) was evaluated for use in monitoring global oxygenation in adult patients after cardiac surgery. DESIGN: Prospective, randomized clinical monitoring study. SETTING: Intensive care unit for cardiac surgery; university hospital. PARTICIPANTS: The study included 35 patients scheduled for cardiac surgery with insertion of a pulmonary artery catheter; patients with known cerebral-vascular perfusion disturbances were excluded. INTERVENTIONS: Noninvasive cerebral NIRS oxygen saturation (rSO(2)) and conventional intensive care monitoring parameters were assessed. MEASUREMENTS AND MAIN RESULTS: Simple regression analysis was used to assess the correlation of rSO(2) to hemodynamic parameters. There was fair-to-moderate intersubject correlation to hemoglobin concentration (r = 0.45, p < 0.0001) and mixed venous oxygen saturation (SmvO(2)) (r = 0.33, p < 0.0001). Sensitivity and specificity of rSO(2) to detect substantial (>or=1 standard deviation) changes in mixed venous oxygen saturation were 94% and 81%, respectively. CONCLUSIONS: Cerebral NIRS in adult patients might not be the tool to replace mixed venous oxygen monitoring. Further work has to be done to assess its potential to reflect intraindividual trends.     

Transcranial regional cerebral oxygen saturation monitoring during carotid endarterectomy as a predictor of postoperative hyperperfusion

OBJECTIVE: Hyperperfusion syndrome is a rare but potentially devastating complication that can occur after carotid endarterectomy (CEA). The purpose of this study was to determine whether intraoperative transcranial regional cerebral oxygen saturation (rSO(2)) monitoring via near-infrared spectroscopy could be reliably used to identify patients at risk for post-CEA hyperperfusion. METHODS: rSO(2) was intraoperatively monitored for 50 patients undergoing CEA for treatment of ipsilateral internal carotid artery stenosis (>/=70%). Cerebral blood flow (CBF) was also assessed, with single-photon emission computed tomography, before and immediately after CEA. RESULTS: Post-CEA hyperperfusion (CBF increase of >/=100%, compared with preoperative values) was observed for six patients. A significant linear correlation was observed between the rSO(2) increases immediately after declamping of the internal carotid artery and the CBF increases immediately after CEA (r(2) = 0.247, P = 0.0002). The sensitivity and specificity of the rSO(2) increases for detection of post-CEA hyperperfusion were 100 and 86.4%, respectively, with a cutoff point of 5%. A strong linear correlation was observed between the rSO(2) increases at the end of the procedure and the CBF increases immediately after CEA (r(2) = 0.822, P < 0.0001). Both the sensitivity and the specificity of the rSO(2) increases for detection of post-CEA hyperperfusion were 100% with a cutoff point of 10%. Hyperperfusion syndrome developed for one patient with post-CEA hyperperfusion, but intracerebral hemorrhage did not occur. CONCLUSION: Intraoperative rSO(2) monitoring can reliably identify patients at risk for hyperperfusion after CEA.     

Near-infrared spectroscopic cerebral oxygenation reading in neonates and infants is associated with central venous oxygen saturation

BACKGROUND: The aim of the study was to elucidate easily determinable laboratory and vital parameters in clinical practice to explain variability of near-infrared spectroscopic cerebral oxygenation readings in critically ill newborns and infants using the NIRO 300 spectrometer. METHODS: Near-infrared spectroscopy (NIRS) cerebral tissue oxygenation index (cTOI) was measured on the forehead of critically ill neonates and infants with existing arterial and/or central venous access. We recorded patient characteristics and simultaneously determined sedation state, hemodynamic, respiratory and laboratory data, such as arterial blood gas analysis, electrolytes, hemoglobin and arterial lactate concentration, blood glucose and central venous oxygen saturation. Data were compared using linear, multiple and forward stepwise regression analysis (P < 0.05). RESULTS: A total of 155 neonates and infants aged from 0 to 365 days (median 12 days) were studied. cerebral tissue oxygenation index (cTOI) values ranged from 32.1 to 91.0% (60.5 +/- 11.5%). Simple linear regression analysis revealed significant associations between cTOI and arterial oxygen saturation (r = 0.254, P = 0.001), transcutaneously measured arterial oxygen saturation (r = 0.320, P < or = 0.0001), central venous oxygen saturation (r = 0.489, P < 0.0001), arteriovenous oxygen extraction (r = 0.445, P < 0.0001) and presence of a cardiac shunt (r = 0.250, P = 0.024). Multiple regression analysis and forward stepwise regression revealed two independent, significant predictors for cTOI, namely SvO2 (P < 0.0001) and presence or absence of a cardiac shunt (P = 0.003). SvO2 alone explained 23.9% of the variability of cTOI. The addition of the variable 'cardiac shunt' improved the model to 33%. CONCLUSIONS: Based on our study results cerebral tissue oxygenation readings by the NIRO 300 near-infrared spectrometer is influenced by central venous oxygen saturation, which partially explains intersubject variability of NIRS cerebral oxygenation readings.     

MELD predictive value of alterations of brain perfusion during liver transplantation

INTRODUCTION: The systemic circulation of patients with liver failure is characterized by low vascular resistance and a compensatorily increased cardiac output. In addition, some patients show functional loss of the autoregulation system for cerebral blood flow, creating enhanced risk during orthotopic liver transplantation (OLT), a possible cause of the high incidence of central nervous system complications after OLT. PATIENTS AND METHODS: Sixteen consecutive patients undergoing OLT were enrolled and characterized by the Child-Pugh (CTP), the MELD, and the HCC-adjusted-MELD score before surgery. OLT was performed with the "piggyback" technique. Brain perfusion and oxygenation was monitored by NIRO300 by Hamamatsu. This instrument detects concentration changes in oxygenated hemoglobin (DeltaHbO(2)), deoxygenated hemoglobin (DeltaHHb), and total volume of hemoglobin (DeltaHbT). It also calculates the tissue oxygenation index (TOI), namely HbO(2)/HbT expressed as a percentage, and the tissue hemoglobin index (THI). RESULTS: The lowest levels of brain perfusion were recorded at the washout, DeltaHbO(2) = -13.95 (-20/-5.3) micromol L(-1) and TOI = 51.5 (35.2/70.7)%, while immediately after, at reperfusion, the highest peaks were observed: DeltaHbO(2) was 0.16 (16.9/13) micromol L(-1); DeltaHbT was 1.1 (22.3/11.8) mumol L(-1); and TOI was 73.6 (78.1/65.3)%. CONCLUSIONS: Patients with more severe liver deficiency scores showed higher levels of brain perfusion and oxygenation during surgery. Both the MELD and the CTP score predict alterations in brain perfusion.     

Tissue oxygenation monitoring during major pediatric surgery using transcutaneous liver near infrared spectroscopy

BACKGROUND: The aim of the study was to compare liver tissue oxygenation determined by near infrared spectroscopy (NIRS) with central venous oxygen saturation (SvO(2)) and intestinal perfusion as measured by gastric intramucosal pH (pHi) in pediatric surgical patients. METHODS: Twenty children undergoing craniofacial surgery with expected major intraoperative blood loss were studied. NIRS tissue oxygenation index (TOI(Liver)) and pHi values were recorded. Arterial blood gas analysis and SvO(2) were assessed from periodically taken blood samples. Data are presented as ranges (median) and were compared using linear regression analysis. Sensitivity and specificity of the intra-individual changes in TOI(Liver) to predict falling SvO(2) or pHi values were calculated. RESULTS: Patients age ranged from 0.79 to 8.27 years (1.92 years). TOI(Liver) ranged from 41.5 to 77.4% (61.5%), gastric pHi from 7.13 to 7.60 (7.37) and SvO(2) from 51 to 86% (74%). Among patients only moderate correlation was found between TOI(Liver) and SvO(2) (r = 0.594, P < 0.0001) and gastric pH(i) (r = 0.502, P < 0.0001). Intra-individual measured TOI(Liver) values, however, demonstrated close correlation with SvO(2) values (r = 0.680 to 0.976) but a varying correlation with gastric pHi values (r = 0.055 to 0.972). Sensitivity/specificity of TOI(Liver) to predict decreasing SvO(2) or gastric pHi values were 76.4/73.4% and 67.4/62.7% respectively. CONCLUSIONS: TOI(Liver) provided a better trend monitor of central venous oxygen saturation than gastric intramucosal pH. Because of its limited sensitivity and specificity to indicate deterioration of SvO(2), liver tissue oxygenation measured by transcutaneous NIRS does not provide additional practical information for clinical management.     

Influence of patient variables and sensor location on regional cerebral oxygen saturation measured by INVOS 4100 near-infrared spectrophotometers

Cerebral oximeter based on near-infrared spectroscopy has been used as a continuous, noninvasive monitoring of regional cerebral oxygen saturation (rSO2). Although the absolute rSO2 values have a wide range of variability, the factors affecting a variability of rSO2 values have not been extensively investigated. The authors investigated the influence of patient variables and sensor location on rSO2 measured by the cerebral oximeter INVOS 4100 in 111 patients anesthetized with sevoflurane, fentanyl, and nitrous oxide in oxygen. The sensors for rSO2 measurements were applied on the right forehead (R), 1 cm lateral to R (R1), on the left forehead (L), 1 cm lateral to L (L1), and on the center of the forehead (C). The relationship between the rSO2 values and patient variables were also analyzed. Values of rSO2 at R1 and L1 were significantly lower than those at R and L, respectively. Values of rSO2 at C were significantly higher compared with those at other sites. There were no significant correlations between the rSO2 values and values of weight, height, and head size. Values of rSO2 were similar between males and females. A significant negative correlation between the rSO2 values and age and a positive correlation between the rSO2 values and hemoglobin concentration were observed. These data indicate that patient age, hemoglobin concentration at the measurement, and sensor location can affect rSO2 values.     

Measurement of cerebral oxygenation state in anaesthetized children using the INVOS 5100 cerebral oximeter

BACKGROUND: Near-infrared spectroscopy is a developing technique for monitoring cerebral oxygenation during anaesthesia. The aim of this study was to evaluate absolute values of cerebral oxygenation during stable anaesthesia conditions in otherwise healthy children using the recently introduced INVOS 5100 cerebral oximeter with a paediatric and adult sensor and to compare them with values obtained from the NIRO 300 oximeter. METHODS: Thirty paediatric surgical patients (aged 0.23-15.97 years) were studied during general anaesthesia with tracheal intubation and controlled ventilation. Comparative measurements of cerebral oxygenation were performed on the forehead with two probes within 10 min under stable cardiorespiratory and anaesthesia conditions. Cerebral oxygenation values (rSO2) obtained from the paediatric and adult INVOS 5100 sensors were compared with the tissue oxygenation index (TOI) obtained from the NIRO 300 cerebral oximeter using 4- and 5-cm emitter-detector separation. RESULTS: Cerebral rSO2 values and the TOI values both showed a large range of cerebral oxygenation in the children studied (rSO2: 59-95%, TOI: 48-85%). Cerebral rSO2 values measured by the INVOS 5100, particularly with the paediatric sensor, were significantly higher than the TOI values obtained from the NIRO 300 (P < 0.0001). Agreement between the INVOS and NIRO oximeter was poor. CONCLUSION: The large range and the poor agreement of cerebral oxygenation values between the two oximeters makes it difficult to define a normal value. Cerebral oxygenation readings by these monitors, based on one single point measurement during anaesthesia, should be viewed with caution. Actually, there may be little indication for routine use of such monitoring during general anaesthesia.     

A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patients

BACKGROUND: Near-infrared spectroscopy (NIRS) is a noninvasive optical monitor of regional cerebral oxygen saturation (rSO2). The aim of this study was to validate the use of NIRS by cerebral oximetry in estimating invasively measured mixed venous oxygen saturation (SvO2) in pediatric postoperative cardiac surgery patients. METHODS: Twenty patients were enrolled following cardiac surgery with intraoperative placement of a pulmonary artery (PA) or superior vena cava (SVC) catheter. Five patients underwent complete biventricular repair--complete atrioventricular canal (n=3) and other (n=2). Fifteen patients with functional single ventricle underwent palliative procedures--bidirectional Glenn (n=11) and Fontan (n=4). Cerebral rSO2 was monitored via NIRS (INVOS 5100) during cardiac surgery and 6 h postoperatively. SvO2 was measured from blood samples obtained via an indwelling PA or SVC catheter and simultaneously correlated with rSO2 by NIRS at five time periods: in the operating room after weaning from cardiopulmonary bypass, after sternal closure, and in the CICU at 2, 4, and 6 h after admission. RESULTS: Each patient had five measurements (total=100 comparisons). SvO2 obtained via an indwelling PA or SVC catheter for all patients correlated with rSO2 obtained via NIRS: Pearson's correlation coefficient of 0.67 (P<0.0001) and linear regression of r2=0.45 (P<0.0001). Separate linear regression of the complete biventricular repairs demonstrated an r=0.71, r2=0.50 (P<0.0001). Bland-Altman analysis showed a bias of +3.3% with a precision of 16.6% for rSO2 as a predictor of SvO2 for all patients. Cerebral rSO2 was a more accurate predictor of SvO2 in the biventricular repair patients (bias -0.3, precision 11.8%), compared with the bidirectional Glenn and Fontan patients. CONCLUSIONS: Regional cerebral oximetry via NIRS correlates with SvO2 obtained via invasive monitoring. However, the wide limits of agreement suggest that it may not be possible to predict absolute values of SvO2 for any given patient based solely on the noninvasive measurement of rSO2. Near-infrared spectroscopy, using the INVOS 5100 cerebral oximeter, could potentially be used to indicate trends in SVO2, but more studies needs to be performed under varying clinical conditions.     

Effect of head elevation on intracranial pressure, cerebral perfusion pressure, and regional cerebral oxygen saturation in patients with cerebral hemorrhage

OBJECTIVE: To study the effects on cerebral dynamics and regional oxygenation (rSO2) of the semi-sitting position, with the head at either 30 degrees or 45 degrees, in surgery for cerebral hemorrhage. PATIENTS AND METHODS: We performed a prospective study of 10 patients undergoing surgery for cerebral hemorrhage under sedation and analgesia and with mechanical ventilation. Intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), and rSO2 measured using near-infrared spectroscopy were recorded with the head in the supine position (0 degrees) and elevated to an angle of 30 degrees and then 45 degrees, following a stabilization period of 5 minutes. RESULTS: Mean (SD) ICP values were significantly lower in both semi-sitting positions than in the supine position: 2.8 (1.4) mm Hg lower at 30 degrees and 4.4 (1.4) mm Hg lower at 45 degrees. Mean CPP values were fell slightly when the head was elevated to 30 degrees (3.5 [3.1] mm Hg, P=.048); a greater reduction was achieved when the head was elevated 45 degrees (7.1 [4.8] mm Hg, P<.01). The greatest reduction in mean MAP values also occurred with the head elevated to 45 degrees (11.8 [4.6] mm Hg, P<.001). Mean rSO2 values fell when the head was elevated to 30 degrees and 45 degrees; the greatest reduction occurred when the head was elevated to 45 degrees (7% [2%], P<.001). There was a moderate correlation between CPP values and changes in rSO2 (r2=0.45, P<.001). CONCLUSION: Head elevation significantly reduces ICP and CPP in patients with cerebral hemorrhage. Head elevation also reduces rSO2, to a greater or lesser extent depending on the degree to which the head is elevated.     

Risk factors of left ventricular hypertrophy in non-dialysis dependent end-stage renal disease patients

Objective To investigate the risk factors of left ventricular hypertrophy (LVH) in non-dialysis dependent end-stage renal disease (ESRD) patients. Methods ESRD patients in the First Affiliated Hospital of Sun Yat-sen University from Jan to July 2019 were enrolled. Demographic data of patients were collected and biochemical parameters were measured. Hydration status index (extracellular water/total body water, ECW/TBW) was measured by bioelectrical impedance analysis (BIA), and LVH was diagnosed by echocardiography. Patients were divided into LVH group and non-LVH group according to LVH diagnostic criteria, and the incidence of LVH in ESRD non-dialysis patients was calculated. Logistic regression was used to analyze the risk factors of LVH. Results A total of 105 non-dialysis dependent ESRD patients aged (47.03±12.56) years (21-78 years) were enrolled in present study, among whom 74 patients (70.5%) had LVH. Compared to non-LVH group, patients in LVH group had higher proportion of diabetes and calcium antagonist used, higher value of ECW/TBW and ECW/Height, higher level of night systolic pressure, and were older (all P＜0.05). Spearman correlation analysis showed LVH was positively correlated to diabetes (r=0.345, P＜0.001), night systolic pressure (r=0.286, P＜0.001), night diastolic pressure (r=0.251, P=0.012), calcium antagonist used (r=0.381, P=0.013), ECW/TBW (r=0.383, P=0.005), ECW/Height (r=0.298, P=0.003), 24 h sodium urinary excretion (r=0.257, P=0.025), brain natriuretic peptide (r=0.315, P=0.005) and hemoglobin (r=0.307, P=0.018), and negatively correlated to 24 h potassium urinary excretion (r=-0.248, P=0.023). Logistic regression showed that increased night diastolic pressure (OR=2.036, 95%CI 1.144-3.623, P=0.016) and ECW/TBW (OR=1.232, 95%CI 1.025-1.523, P=0.014）were the independent risk factors of LVH after adjusting for gender, age, diabetes, nocturnal blood pressure, antihypertensive drugs used, ECW/TBW, urinary sodium excretion and hemoglobin. Conclusions LVH is common in non-dialysis dependent ESRD patients. Over hydration and high night diastolic blood pressure are the independent risk factors of LVH in non-dialysis dependent ESRD patients.     

Four-side near-infrared spectroscopy measured in a paediatric population during surgery for congenital heart disease

In this study we monitored renal, hepatic and muscular oxygen saturations by near-infrared spectroscopy and we evaluated the correlation with variables that could affect tissue oxygenation in 16 paediatric patients during surgical heart procedure. We considered the following phases: 1) basal time (after induction of anaesthesia and before median sternotomy), 2) before starting cardiopulmonary bypass, 3) 15 min after starting it, 4) at half time, 5) 15 min before the end, 6) at the end, 7) 15 min after the end, and 8) 10 min before paediatric intensive care unit admission. Heart rate, mean arterial pressure, peripheral oxygen saturation, serum lactate, haemoglobin, blood gas analysis, and rectal temperature were registered. We found a decrease of all monitored regional saturations (rSO(2)) (cerebral P = 0.006, hepatic P = 0.005) before starting the bypass. After this time, cerebral saturation gradually increased without reaching the basal value; renal and liver saturations increased after starting bypass; muscular rSO(2) increased in the second half (P = 0.005). A statistically significative inverse correlation between cerebral rSO(2) and pH was observed. In conclusion, during paediatric heart surgery a vulnerable period was identified. We underline the necessity to monitor this phase.     

Predictors and relationships of serum 25 hydroxyvitamin D concentration with bone turnover markers, bone mineral density, and vitamin D receptor genotype in Emirati women

OBJECTIVES: To determine factors influencing serum 25 hydroxyvitamin D (25OHD) concentration and relationships between serum 25OHD concentration, bone turnover markers, bone mineral density (BMD), and vitamin D receptor (VDR) genotype in Emirati women. METHODS: Serum 25OHD, parathyroid hormone (PTH), osteocalcin (OC), vitamin D binding protein (VDBP), and urinary deoxypyrdinoline (UDPD) concentrations and VDR genotype were determined in Emirati women volunteers who were participating in a study aiming at establishing a reference database for BMD. RESULTS: Serum 25OHD concentration in the 259 women volunteers was 25.3 +/- 10.8 nmol/l (mean +/- SD), and all had vitamin D deficiency (25OHD <80 nmol/l). Mean serum 25OHD was highest in April (29.2 +/- 13.0 nmol/l), which marks the end of the short and cooler winter season, and lowest in August (18.2 +/- 5.9 nmol/l). No significant difference in 25OHD concentration was noted among Emirati women wearing different dress styles, but the mean serum 25OHD was significantly lower in comparison with non-Arab Caucasian women volunteers who dressed in a Western style (P < 0.001). Serum 25OHD correlated positively with age (r = 0.2), number of pregnancies (r = 0.16), dietary vitamin D intake (r = 0.15), serum calcium (r = 0.14), phosphorus (r = 0.14), VDBP (r = 0.15), and urinary calcium/creatinine (r = 0.2), and inversely with PTH (r = -0.22), OC (r = -0.13), and UDPD/creatinine (r = -0.15); P < 0.05 for all correlations. Multiple linear regression analysis showed that age, dietary vitamin D intake, multivitamin intake, and cooler season were independent positive predictors of serum 25OHD concentration (R(2) = 0.18). The frequencies of VDR genotypes were 36% GG, 44.1% AG, and 19.9% AA. Allele frequencies were 58% for G allele and 42% for A allele and were in Hardy-Weinberg equilibrium (x(2) = 1.44; P > 0.1). There was no statistically significant influence of VDR genotype on bone turnover or BMD. CONCLUSIONS: Vitamin D deficiency is highly prevalent in Emirati women and appears largely attributable to insufficient sunlight exposure. It is associated with increased bone turnover. VDR genotype does not appear to influence bone turnover markers or BMD in Emirati women.     

维持性血液透析患者血氨基末端脑钠肽前体水平与肾性贫血的相关性

目的探讨维持性血液透析(MHD)患者发生肾性贫血的危险因素,分析其与血氨基末端脑钠肽前体(NT⁃proBNP)的相关关系。方法选取2018年8月至2018年11月期间在复旦大学附属华山医院接受MHD 3个月以上、病情稳定的患者为研究对象。按照血红蛋白(Hb)水平分为贫血组和非贫血组。回顾性收集患者一般资料、观察期内实验室检查及透析相关资料。Pearson相关分析法分析贫血指标与透析相关指标、血NT⁃proBNP水平的相关性;逐步多元线性回归法分析MHD患者发生贫血的危险因素。结果共160例MHD患者入选本研究,年龄(63.11±11.35)岁,男79例(49.4%),女81例(50.6%)。患者透析龄(118.01±82.32)个月,血红蛋白(110.09±13.48)g/L,NT⁃proBNP水平中位数为3985 ng/L。贫血组73例(45.6%),非贫血组87例(54.4%),贫血组血NT⁃proBNP水平显著高于非贫血组(t=-3.714,P<0.001)。MHD患者血红蛋白水平与每周透析时间(r=0.228)和血白蛋白(r=0.349)呈正相关,与血NT⁃proBNP水平呈负相关(r=-0.318);血细胞比容与每周透析时间(r=0.283)、血清钙(r=0.317)、血磷(r=0.264)、白蛋白(r=0.513)呈正相关(均P<0.05)。逐步多元线性回归分析结果显示,低血白蛋白、高NT⁃proBNP水平是MHD患者发生肾性贫血的独立危险因素。结论MHD患者NT⁃proBNP水平升高与血红蛋白水平降低相关,低血白蛋白、高NT⁃proBNP是MHD患者发生贫血的危险因素。提示肾性贫血的治疗需要考虑改善营养不良和高容量等因素。     

An evaluation of bilateral monitoring of cerebral oxygen saturation during pediatric cardiac surgery

Cerebral oximetry is a technique that enables monitoring of regional cerebral oxygenation during cardiac surgery. In this study, we evaluated differences in bi-hemispheric measurement of cerebral oxygen saturation using near-infrared spectroscopy in 62 infants undergoing biventricular repair without aortic arch reconstruction. Left and right regional cerebral oxygen saturation index (rSO2i) were recorded continuously after the induction of anesthesia, and data were analyzed at 12 time points. Baseline rSO2i measurements were left 65 +/- 13 and right 66 +/- 13 (P = 0.17). Mean left and right rSO2i measurements were similar (< or =2 percentage points/absolute scale units) before, during, and after cardiopulmonary bypass, irrespective of the use of deep hypothermic circulatory arrest. Further longitudinal neurological outcome studies are required to determine whether uni- or bi-hemispheric monitoring is required in this patient population.     

Cerebral oxygen balance is impaired during repair of aortic coarctation in infants and children

OBJECTIVE: During repair of aortic coarctation through a left thoracotomy without cardiopulmonary bypass, clamping the proximal transverse aortic arch occludes antegrade flow to the left carotid and vertebral arteries. It is assumed that flow through the right carotid and vertebral arteries is adequate for cerebral perfusion. The study objective is to determine whether aortic occlusion impairs left hemispheric cerebral oxygen balance measured by near-infrared spectroscopy. METHODS: In 18 children having repair of aortic coarctation, we measured the maximum change and integral for hemoglobin D (difference of oxyhemoglobin and deoxyhemoglobin), total oxygenation index, and the redox state of cytochrome aa3. Thirteen subjects had recordings from the left hemisphere to test the hypothesis that aortic occlusion impairs left hemispheric oxygen balance. Five subjects had recordings from the right hemisphere for comparison. RESULTS: After aortic clamping, a significant decrease in hemoglobin D was observed in recordings from the left hemisphere compared with those from the right hemisphere (P = .03, maximum change in hemoglobin D). Total oxygenation index and cytochrome aa3 were generally preserved. There was an inverse linear relationship for the change in hemoglobin D during clamp application and after removal (Spearman rho = -0.74), with increased hemoglobin D after clamp removal in those subjects with the greatest decrease of hemoglobin D during arch occlusion. Linear regression analysis identified nitroprusside administration as significantly associated with a decrease in hemoglobin D (P < .001). CONCLUSIONS: Significant impairment in left hemispheric cerebral oxygen balance was identified during arch clamping. The neurodevelopmental significance of impaired cerebral oxygen balance detected by near-infrared spectroscopy during aortic coarctation repair remains to be elucidated.     

Local haemodynamic changes during carotid endarterectomy--the influence on cerebral oxygenation.

OBJECTIVES: To characterize carotid bifurcation haemodynamics and cerebral oxygenation during clamping and at reperfusion after carotid endarterectomy (CEA). MATERIALS AND METHODS: Sixty-two patients with a symptomatic high-grade stenosis of the internal carotid artery (ICA), who underwent CEA under general anaesthesia, were studied prospectively. Measurements of stump-pressure, volume flow (transit time flowmetry) and changes in cerebral oxygenation (near-infrared spectroscopy (NIRS)) were performed. Selective shunting was based on stump pressure only. RESULTS: Stump pressure correlated with both ICA flow before clamping (r=0.45; p=0.03) and changes in cerebral oxygenation (rSO2) during clamping (r=0.61; p=0.002), the latter was reversed by shunt placement. ICA flow before clamping also correlated with changes in rSO2 during clamping (r=0.41; p=0.01). CONCLUSION: Measurements with transit time flowmetry and cerebral oximetry are technically easy and help to determine the need for selective shunting during CEA. High ICA flow before clamping in combination with a low stump pressure usually indicates the need for a shunt. Volume flow measurements may also be useful in the quality assessment of the CEA.     

The influence of positioning on spectroscopic measurements of brain oxygenation

This study was designed to evaluate the influence of body position during neurosurgical and cerebrovascular operations on regional cerebral oxygen saturation (rSO2). Awake volunteers (group I; n = 14), anesthetized patients (group II; n = 48) undergoing lumbar discectomy, and 12 patients undergoing carotid endarterectomy (group III) with internal carotid artery (ICA) stenosis were studied. Anesthesia in the patient groups was performed with sevoflurane (1.1 Vol% insp.) in N2O2/O2 mixture (FiO2 0.4) rSO2 was monitored with a INVOS 4100 cerebral oxymeter (Somanetics Corporation, Troy, MI). Measurements were done in all groups in supine position with head turned to the right and left side. Furthermore, in groups I and II, rSO2 was measured in right lateral, left lateral, prone, or sitting position. In each position the parameters were registered at three times (1, 3, and 5 min after taking up the position). In the healthy volunteers, the mean rSO2 values of both hemispheres were 71.3 +/- 5.0%. No significant changes of rSO2 were found interhemispherical and upon turning the head to both sides or positioning to the prone and both lateral positions. After assuming the sitting position, the decrease of rSO2 was not significant. In group II, rSO2 decreased significantly in the sitting position. In group III, baseline readings for rSO2 obtained from the side of ICA stenosis were significantly lower, compared to the contralateral side. After turning the head to the ipsilateral side, this difference diminished. In contrast, turning the head toward the contralateral side, the rSO2 difference remained nearly constant, both values decreasing constantly throughout the observation period. In conclusion, after different positioning maneuvers awake and under anesthesia, alterations of rSO2 can be registrated by near-infrared spectroscopy (NIRS).