Cerebral Tissue Oxygen Saturation Research Articles

A Pilot Randomized Controlled Study of Mild Hypercapnia During Cardiac Surgery With Cardiopulmonary Bypass

To test whether targeted therapeutic mild hypercapnia (TTMH) would attenuate cerebral oxygen desaturation detected using near-infrared spectroscopy during cardiac surgery requiring cardiopulmonary bypass (CPB). Randomized controlled trials. Operating rooms and intensive care unit of tertiary hospital. The study comprised 30 patients undergoing cardiac surgery with CPB. Patients were randomly assigned to receive either standard carbon dioxide management (normocapnia) or TTMH (target arterial carbon dioxide partial pressure between 50 and 55 mmHg) throughout the intraoperative period and postoperatively until the onset of spontaneous ventilation. Relevant biochemical and hemodynamic variables were measured, and cerebral tissue oxygen saturation (SctO2) was monitored with near-infrared spectroscopy. Patients were followed-up with neuropsychological testing. Patient demographics between groups were compared using the Fisher exact and Mann-Whitney tests, and SctO2 between groups was compared using repeated measures analysis of variance. The median patient age was 67 years (interquartile range [IQR] 62-72 y), and the median EuroSCORE II was 1.1. The median CPB time was 106 minutes. The mean intraoperative arterial carbon dioxide partial pressure for each patient was significantly higher with TTMH (52.1 mmHg [IQR 49.9-53.9 mmHg] v 40.8 mmHg [IQR 38.7-41.7 mmHg]; p < 0.001) as was pulmonary artery pressure (23.9 mmHg [IQR 22.4-25.3 mmHg] v 18.5 mmHg [IQR 14.8-20.7 mmHg]; p = 0.004). There was no difference in mean percentage change in SctO2 during CPB in the control group for both hemispheres (left: -6.7% v -2.3%; p = 0.110; right: -7.9% v -1.0%; p = 0.120). Compliance with neuropsychological test protocols was poor. However, the proportion of patients with drops in test score >20% was similar between groups in all tests. TTMH did not increase SctO2 appreciably during CPB but increased pulmonary artery pressures before and after CPB. These findings do not support further investigation of TTMH as a means of improving SctO2 during and after cardiac surgery requiring CPB.

Neonatal cardiopulmonary transition in an ovine model of congenital diaphragmatic hernia

ObjectiveInfants with a congenital diaphragmatic hernia (CDH) are at high risk of developing pulmonary hypertension after birth, but little is known of their physiological transition at birth. We aimed to...

Lack of Variability in Cerebral Oximetry Tendency in Infants with Severe Hypoxic-Ischemic Encephalopathy Under Hypothermia.

Cerebral oximetry using near-infrared spectroscopy (NIRS) provides continuous, noninvasive assessment of the degree of hemoglobin saturation of the brain tissue. Previous studies suggest that high values of regional cerebral tissue oxygen saturation (rScO2) during the first days in neonates with significant hypoxic-ischemic encephalopathy (HIE) are correlated with an adverse neurological outcome. However, the results are not consistent among the studies. To examine the correlation of rScO2 values and their variability over time with HIE severity, amplitude integrated electroencephalography (aEEG) background and seizure activity, neuron-specific enolase levels in cerebrospinal fluid, magnetic resonance imaging (MRI) findings, and neurological outcome. Retrospective study that included all consecutive infants with moderate-to-severe HIE born at ≥35 weeks gestational age admitted between January 2011 and December 2014. NIRS monitoring was initiated at admission and maintained during therapeutic hypothermia up to 12 hours after rewarming. To analyze rScO2, different periods (0-6, 6-24, 24-48, 48-72, and 72-100 hours of life) and three ranges (<55%, 55-90%, >90%) were considered. Variability in each patient was considered ≤5% when changes in rScO2 values in all periods were ≤5%. Twenty-three newborns were included. Infants who suffered from severe HIE, seizures, abnormal aEEG background, altered MRI or death, and abnormal outcome had rScO2 values >90% and with less variability (≤5%). rScO2 values >90% and a lack of variability over time in infants with HIE during cooling provide useful information about the severity of neurological status.

Predicting postoperative delirium and postoperative cognitive decline with combined intraoperative electroencephalogram monitoring and cerebral near-infrared spectroscopy in patients undergoing cardiac interventions.

Studies have associated electroencephalogram (EEG) suppression with postoperative delirium (POD) and postoperative cognitive decline (POCD). Otherwise, improving cerebral tissue oxygen saturation (rScO2) seems beneficial. No study has evaluated the impact of EEG suppression and decreased rScO2 on the incidence of POD and POCD when the intraoperative management of patients is performed with a depth-of-anesthesia (DOA) monitor and a cerebral oximetry. In this prospective study patients undergoing cardiac interventions were monitored with the NeuroSENSE® DOA monitor and bilateral cerebral oximetry. An algorithm was used to optimize cerebral oxygenation. EEG suppression was presented as total area under the curve (AUC) of suppression ratio (SR) > 0s (AUCEEGSR>0s). Cerebral desaturation was defined as AUC of 25% drop of oximetry values as compared to baseline. POD was evaluated by the chart review method. POCD was defined as a Z-score ≤ 2 based on Mini Mental State Examination at baseline and day 5 or if the patient reported any cognitive decline at 3 and at 6 months postoperatively. Among the 1616 patients, 1513 underwent normothermic surgery and were further analyzed. POD and POCD were respectively evaluated in 1504 and 1350 patients of whom 303 (20%) and 270 (20%) were respectively diagnosed positive. Having experienced high magnitudes of EEG suppression (fourth quartile of AUCEEGSR>0s) was significantly associated with POD (OR = 2.247; 95% CI = 1.414-3.571; P = 0.001). Low rScO2 at the end of surgery was statistically associated with POCD (OR = 0.981; 95% CI = 0.965-0.997; P = 0.018). The results of our study show that the degree of intraoperative EEG suppression on one hand, and low rScO2 at the end of procedure on the other hand, are associated with respectively POD and POCD in patients undergoing cardiac interventions.

Effects of blood transfusion on regional tissue oxygenation in preterm newborns are dependent on the degree of anaemia.

Most of the preterm infants are transfused at least once during their stay in the neonatal intensive care unit (NICU). The aims of this study were to demonstrate if packed red blood cell (pRBC) transfusion modulates regional (cerebral, abdominal, renal) tissue oxygen saturation measured by near-infrared spectroscopy (NIRS) and to demonstrate if we can use NIRS to guide transfusion decisions in neonates. A multi-probe NIRS device was applied to anaemic preterm infants of gestational age <33 weeks for 30-60 min before and 24 h after pRBC transfusion. We evaluated the results separately in the subgroup with a pre-transfusion haemoglobin (Hb) < 8 g/dL. Cerebral, abdominal and renal tissue oxygen saturation (rSO2 ) and abdominal/cerebral, abdominal/renal and renal/cerebral rSO2 ratios before and 24 h after transfusion were compared. There was no significant difference in cerebral rSO2 and abdominal/renal rSO2 ratios before and 24 h after transfusion, but abdominal and renal rSO2 and abdominal/cerebral and renal/cerebral rSO2 ratios at the 24th h following transfusion increased significantly. This increase was observed in the subgroup with pre-transfusion Hb < 8 g/dL. Although statistically significant, the increase in renal oxygenation was within the limits of variability. The increase in tissue oxygenation in abdominal region after pRBC transfusion suggests decreased tissue oxygenation of intestines during severe anaemia despite cerebral oxygenation being maintained at that particular Hb level. The impact of the increase on renal oxygenation with pRBC transfusion is unclear and might need further investigation. Increase in abdominal rSO2 may cause reperfusion injury, oxidative damage and trigger necrotising enterocolitis.

Modern technology-derived normative values for cerebral tissue oxygen saturation in adults.

Modern near-infrared spectroscopy technology is increasingly adopted to measure cerebral tissue oxygen saturation. However, the normal range of cerebral tissue oxygen saturation in adults with such technology is unknown. We sought to measure cerebral tissue oxygen saturation in healthy volunteers using the novel O3 Regional Oximetry® device (Masimo Corporation, Irvine, CA, USA) and assess its relationship with key physical and haemodynamic characteristics. For ≥5 minutes, we continuously recorded cerebral tissue oxygen saturation, pulse oximetry, cardiac index and mean arterial pressure. We assessed for differences in cerebral tissue oxygen saturation between hemispheres, sex, skin type, comorbidity or smoking status, and for associations between cerebral tissue oxygen saturation and age, height, weight, SpO2and haemodynamic parameters. We recorded >32,000 observations in 98 volunteers aged 22 to 60 years, including 41 (42%) males. One-fifth had one or more co morbidities ( n=22, 22.5%), one-tenth were either current or former-smokers ( n=13, 13%), and most had a Fitzpatrick skin type of 3 or lower ( n=84, 86%). The mean combined average cerebral tissue oxygen saturation was 67.6% (95% confidence interval 66.8%-68.6%). We found statistically significant differences in cerebral tissue oxygen saturation according to hemisphere and an association between cerebral tissue oxygen saturation and mean arterial pressure and cardiac index. The combined average cerebral tissue oxygen saturation in 98 healthy volunteers was 67.6% with a narrow confidence interval and no combined average cerebral tissue oxygen saturation was below 56%. We also observed statistically significant yet quantitatively small cerebral tissue oxygen saturation differences between hemispheres, and an association between cerebral tissue oxygen saturation and mean arterial pressure and cardiac index.

Abstract 159: Epinephrine Increases Cerebral Perfusion and Oxygenation in a Pre-Clinical Model of Pediatric In-Hospital Cardiac Arrest

Introduction: Despite controversies, epinephrine remains a mainstay of CPR. Recent animal studies have suggested that epinephrine may decrease cerebral blood flow (CBF) and cerebral oxygenation, possibly potentiating neurological injury during CPR. We investigated the cerebrovascular effects of intravenous epinephrine in a swine model of pediatric in-hospital cardiac arrest. Hypothesis: Epinephrine will increase CBF and cerebral oxygenation during CPR. Methods: One-month old piglets (n=20, 8-10kg) underwent asphyxia for 7 minutes, VF, and CPR according to AHA guidelines for 10-20 minutes. Epinephrine boluses (20 mcg/kg) were administered at minutes 2, 6, 10, and 14 of CPR. Invasive (laser Doppler) and noninvasive (diffuse optical) continuous measurements of CBF and oxygenation were recorded. Wilcoxon Rank-Sum test was used to compare measurements 15 seconds prior to epinephrine doses to sequential measurements at 1-minute intervals following epinephrine; data are described as median [IQR]. Results: Compared to pre-epinephrine values, CBF was most significantly increased one minute after the first dose of epinephrine (noninvasive: +37.7% [6.1, 79]; invasive: +24% [-0.3, 118], p&lt;0.004 for both) and returned to baseline by 3 minutes post-epinephrine. Cerebral tissue oxygenation was also most significantly increased one-minute after the first dose of epinephrine (noninvasive: +25.2% [9.0, 45]; invasive: +160% [30.3, 428], p&lt;0.001 for both) and remained elevated 4 minutes post-epinephrine. Effects were also significant one minute following the second dose on CBF (noninvasive: +11.5% [4.5, 29]; invasive: +9.5% [0.6, 19, p&lt;0.03 for both) and on cerebral tissue oxygenation (noninvasive: +12.3% [1.6, 19]; invasive: +17.8% [-2.3,34, p&lt;0.037 for both). There was no significant effect on any parameter following the third and fourth doses. Conclusions: In a swine model of pediatric in-hospital cardiac arrest, bolus-dosed epinephrine increases CBF and cerebral tissue oxygen saturation. These effects are only significant following the first two doses. Our findings are underscore the importance of further research to elucidate the transient pharmacodynamics of epinephrine to optimize both survival and neurological outcomes.

A prospective, observational study of cerebrovascular autoregulation and its association with delirium following cardiac surgery.

This aim of this prospective observational cohort study was to evaluate any association between postoperatively impaired cerebrovascular autoregulation and the onset of delirium following cardiac surgery. Previous studies have shown that impaired intra-operative cerebrovascular autoregulation during cardiopulmonary bypass is associated with delirium. However, postoperative changes in cerebrovascular autoregulation and its association with delirium have not been investigated. One-hundred and eight consecutive adult cardiac surgical patients without baseline cognitive dysfunction or aphasia were included in the study. Cerebrovascular autoregulation was assessed by the Pearson correlation between near-infrared spectroscopy-derived cerebral tissue oxygen saturation and mean arterial pressure to derive the tissue oximetry index. Cerebrovascular autoregulation was monitored for a minimum of 90min on postoperative day 0 and postoperative day 1. Delirium was assessed throughout intensive care unit admission using the confusion assessment method for the intensive care unit. We observed delirium in 24 of the 108 patients studied. The mean (SD) tissue oximetry index was higher in delirious patients on postoperative day 0 compared with non-delirious patients; 0.270 (0.199) vs. 0.180 (0.142), p=0.044, but not on postoperative day 1; 0.130 (0.160) vs. 0.150 (0.130), p=0.543. All patients showed improvement in tissue oximetry index on postoperative day 1 compared with postoperative day 0. Logistic regression analysis demonstrated tissue oximetry index on postoperative day 0 to be independently associated with delirium; odds ratio 1.05 (95%CI 1.01-1.10), p=0.043. In conclusion, we found an association between impaired cerebrovascular autoregulation, measured by near-infrared spectroscopy, and delirium in the early postoperative period.

Vasopressor Infusion After Subarachnoid Hemorrhage Does Not Increase Regional Cerebral Tissue Oxygenation.

Vasopressors are commonly used after aneurysmal subarachnoid hemorrhage (aSAH) to sustain cerebral pressure gradients. Yet, the relationship between vasopressors and the degree of cerebral microcirculatory support achieved remains unclear. This study aimed to explore the changes in cerebral and peripheral regional tissue oxygen saturation (rSO2) as well as blood pressure (BP) before and after vasopressor infusion in patients with aSAH. Continuous noninvasive cerebral and peripheral rSO2 was obtained using near-infrared spectroscopy for up to 14 days after aSAH. Within-subject differences in rSO2 before and after the commencement of vasopressor infusion were analyzed controlling for Hunt and Hess grade and vasospasm. Of 45 patients with continuous rSO2 monitoring, 19 (42%) received vasopressor infusion (all 19 on norepinephrine, plus epinephrine in 2 patients, phenylephrine in 4 patients, and vasopressin in 2 patients). In these 19 patients, their vasopressor infusion times were associated with higher BP (systolic [b = 15.1], diastolic [b = 7.3], and mean [b = 10.1]; P = .001) but lower cerebral rSO2 (left cerebral rSO2 decreased by 4.4% [b = -4.4, P < .0001]; right cerebral rSO2 decreased by 5.5% [b = -5.5, P = .0002]). Despite elevation in systemic BP during vasopressor infusion times, cerebral rSO2 was concurrently diminished. These findings warrant further investigation for the effect of induced hypertension on cerebral microcirculation.

RELATIONSHIPS BETWEEN NEAR-INFRARED SPECTROSCOPY, PREDUCTAL PERFUSION INDEX AND CARDIAC OUTPUTS IN EXTREMELY PRETERM INFANTS IN THE FIRST 72 HOURS OF LIFE

Abstract BACKGROUND Assessment of hemodynamics during the transitional period in preterm infants is challenging. OBJECTIVES We aimed to describe the relationship between cerebral regional tissue oxygenation saturation (CrSO2), preductal perfusion index (PI), echocardiographic and clinical parameters in extremely preterm infants in their first 72 hours of life. DESIGN/METHODS This single center prospective observational study was conducted in the level 3 neonatal intensive care unit of Sainte-Justine Hospital between July 2015 and May 2016. Twenty newborns born at &lt;28 weeks of gestation were continuously monitored with CrSO2 and preductal PI as well as cardiac outputs measured at 6, 24, 48 and 72 hours of life. Data were assessed for normality and Pearson correlation statistics were performed. Serial data were tested using a one-way ANOVA with repeated measures and Bonferroni adjustment. The level of significance was set to 0.05 RESULTS Median gestational age and birth weight were 25.0 weeks (24–26) and 750 g (655–920) respectively. Table 1 describes the measures over the 72 hours of the study period. CrSO2 and preductal PI were weakly correlated with mean blood pressure, PaCO2, lactates and haemoglobin. Fifteen patients had at least one episode of low left and/or right ventricular output (RVO) measured and showed strong correlation between CrSO2 and superior vena cava (SVC) flow at H6 (r=0.74) and H24 (r=0.86) and between PI and RVO at H6 (r=0.68) and H24 (r=0.92). Five patients had low SVC flowat H6 and showed strong correlation between PI and RVO (r=0.98). CONCLUSION CrSO2 and preductal PI were weakly correlated with clinical parameters in the preterm infants. However, CrSO2 and PI showed stronger correlation with RVO and SVC flow during low cardiac output states.

Near-Infrared Cerebral Oximetry to Predict Outcome After Pediatric Cardiac Surgery: A Prospective Observational Study.

To assess whether near-infrared cerebral tissue oxygen saturation, measured with the FORESIGHT cerebral oximeter (CAS Medical Systems, Branford, CT) predicts PICU length of stay, duration of invasive mechanical ventilation, and mortality in critically ill children after pediatric cardiac surgery. Single-center prospective, observational study. Twelve-bed PICU of a tertiary academic hospital. Critically ill children and infants with congenital heart disease, younger than 12 years old, admitted to the PICU between October 2012 and November 2015. Children were monitored with the FORESIGHT cerebral oximeter from PICU admission until they were weaned off mechanical ventilation. Clinicians were blinded to cerebral tissue oxygen saturation data. None. Primary outcome was the predictive value of the first 24 hours of postoperative cerebral tissue oxygen saturation for duration of PICU stay (median [95% CI], 4 d [3-8 d]) and duration of mechanical ventilation (median [95% CI], 111.3 hr (69.3-190.4 hr]). We calculated predictors on the first 24 hours of cerebral tissue oxygen saturation monitoring. The association of each individual cerebral tissue oxygen saturation predictor and of a combination of predictors were assessed using univariable and multivariable bootstrap analyses, adjusting for age, weight, gender, Pediatric Index of Mortality 2, Risk Adjustment in Congenital Heart Surgery 1, cyanotic heart defect, and time prior to cerebral tissue oxygen saturation monitoring. The most important risk factors associated with worst outcomes were an increased SD of a smoothed cerebral tissue oxygen saturation signal and an elevated cerebral tissue oxygen saturation desaturation score. Increased SD of a smoothed cerebral tissue oxygen saturation signal and increased depth and duration of desaturation below the 50% saturation threshold were associated with longer PICU and hospital stays and with longer duration of mechanical ventilation after pediatric cardiac surgery.

Cerebral desaturation in heart failure: Potential prognostic value and physiologic basis.

Cerebral tissue oxygen saturation (SctO2) reflects cerebral perfusion and tissue oxygen consumption, which decline in some patients with heart failure with reduced ejection fraction (HFrEF) or stroke, especially during exercise. Its physiologic basis and clinical significance remain unclear. We aimed to investigate the association of SctO2 with oxygen transport physiology and known prognostic factors during both rest and exercise in patients with HFrEF or stroke. Thirty-four HFrEF patients, 26 stroke patients, and 17 healthy controls performed an incremental cardiopulmonary exercise test using a bicycle ergometer. Integrated near-infrared spectroscopy and automatic gas analysis were used to measure cerebral tissue oxygenation and cardiac and ventilatory parameters. We found that SctO2 (rest; peak) were significantly lower in the HFrEF (66.3±13.3%; 63.4±13.8%,) than in the stroke (72.1±4.2%; 72.7±4.5%) and control (73.1±2.8%; 72±3.2%) groups. In the HFrEF group, SctO2 at rest (SctO2rest) and peak SctO2 (SctO2peak) were linearly correlated with brain natriuretic peptide (BNP), peak oxygen consumption (), and oxygen uptake efficiency slope (r between -0.561 and 0.677, p < 0.001). Stepwise linear regression showed that SctO2rest was determined by partial pressure of end-tidal carbon dioxide at rest (PETCO2rest), hemoglobin, and mean arterial pressure at rest (MAPrest) (adjusted R = 0.681, p < 0.05), while SctO2peak was mainly affected by peak carbon dioxide production () (adjusted R = 0.653, p < 0.05) in patients with HFrEF. In conclusion, the study delineates the relationship of cerebral saturation and parameters associated with oxygen delivery. Moreover, SctO2peak and SctO2rest are correlated with some well-recognized prognostic factors in HFrEF, suggesting its potential prognostic value.

Relationship between cerebral oxygen saturation and hemodynamics under different end-tidal carbon dioxide partial pressure in children with ventricular septal defect

Objective To study the relationship between regional cerebral tissue oxygen saturation (rScO2) and hemodynamic parameters under different end-tidal carbon dioxide partial pressure (PetCO2) levels during anesthesia induction period in children undergoing ventricular septal defect(VSD) repair. Methods A total of 25 patients aged from 2 to 37 months (median 6 months) were enrolled, who received selective VSD repair at Beijing Anzhen Hospital from April to May 2017.After admission, anesthesia induction and intubation, invasive radial artery pressure were established routinely and hemodynamic device-MostCare was used, Fore-Sight was used to monitor rScO2 of the right frontal brain.By means of adjusting mechanical ventilation parameter, PetCO2 was maintained at 30 (T1), 35 (T2), 40 (T2), 45 (T3) mmHg(1 mmHg=0.133 kPa) in sequence.Pulse oxygen saturation (SpO2), heart rate (HR), systolic pressure (SysP), difference between dicrotic pressure(DicP) and diastolic pressure(DiaP) (Pdic-a), stroke volume index (SVI), cardiac index (CI), systemic vascular resistance index (SVRI), and pulse pressure variation (PPV) were recorded at T1, T2, T3 and T4. Results (1) Comparison among groups: rScO2 at T4, T3, T2 and T1 were(80.5±4.0)%, (78.2±4.6)%, (74.4±5.7)%, (70.8±6.5)%, respectively, rScO2 at T2, T3 and T4 were higher than that at T1, and the differences were statistically significant (all P 0.05). Conclusions During anesthesia induction in ventricular septal defect children, rScO2 increases significantly with the increase in PetCO2.When PetCO2 is at 30 and 35 mmHg, rScO2 is mainly affected by hemodynamics.When PetCO2 is at 40 and 45 mmHg, rScO2 is mainly affected by PetCO2, but less affected by hemodynamics. Key words: Congenital heart disease; Cerebral oxygen saturation; Hemodynamics; End-tidal carbon dioxide

Compression stockings reduce the incidence of hypotension but not that of cerebral desaturation events in the beach-chair position: a randomized controlled trial.

BackgroundThe beach-chair position (BCP) results in decreases in venous return, cardiac output, and cerebral perfusion pressure. In this randomized, prospective study, we investigated whether applying thigh-high compression stockings affected the maintenance of regional cerebral tissue oxygen saturation (rSO2) in the BCP.MethodsPatients undergoing orthopedic surgery in the BCP under general anesthesia were included and assigned randomly to the control or the compression stocking group. Appropriately sized thigh-high compression stockings were applied to the patients in the stockings group. All patients were tilted, up to 45°, throughout the operation. Non-invasive blood pressure, invasive arterial blood pressure zeroed at the external auditory meatus, and rSO2 were recorded.ResultsData were analyzed from 19 patients per group. In the BCP, the values of rSO2 and blood pressure decreased significantly compared with those at baseline, with no significant difference between the groups. The incidences of cerebral desaturation events (CDEs) were similar between the groups; however, that of hypotension was significantly lower in the compression stocking group. During 36 CDEs, the levels of rSO2 and blood pressure decreased significantly compared with those at baseline in both groups. No significant correlation was found between rSO2 and blood pressure.ConclusionsThigh-high compression stockings reduced the incidence of hypotension but not that of CDEs. Our results suggest that other factors, beyond hypotension itself, contribute to CDEs and in other words, efforts just to reduce the incidence of hypotension may not mainly contribute to a reduction of CDEs occurrence in the BCP under general anesthesia.

Influential factors of cerebral oxygen saturation in pediatric cardiovascular surgery

To determine the intervention measures for the decrease of cerebral tissue oxygen saturation during anesthesia for the congenital heart disease in children. Methods: Twenty-eight children with cardiac surgery were enrolled. Anesthesia was deepened with propofol (3 mg/kg) intravenous injection. The data of cerebral tissue oxygen saturation(SctO2), mean arterial pressure (MAP), HR, bispectral index (BIS), arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), hemoglobin (Hb) and middle cerebral artery (MCA) mean flow velocity (Vm) at different points were collected after intravenous injection of propofol at 3 mg/kg. The changes of SctO2 and the influential factors were analyzed. Results: SctO2 decreased by 4.99% after deepen anesthesia, with 95% CI 4.33% to 5.65% (P>0.05). There was no significant differince in MAP, PaO2, PaCO2, and Hb between the time points after deepen anesthesia and the baseline (P>0.05). MCA Vm decreased obviously after deepen anesthesia for 1, 5, 10 min (P<0.05). The decrease in MAP, HR, PaCO2 and MCA Vm is positively correlated with the decrease in SctO2. Conclusion: The decrease of MAP, HR, PaCO2, and MCA Vm is the risk factor for SctO2. To avoid the decrease, it needs to maintain the stability of SctO2 and prevent neurological complications.

Hemodynamic Changes During Rewarming Phase of Whole-Body Hypothermia Therapy in Neonates with Hypoxic-Ischemic Encephalopathy

To delineate the systemic and cerebral hemodynamic response to incremental increases in core temperature during the rewarming phase of therapeutic hypothermia in neonatal hypoxic-ischemic encephalopathy (HIE). Continuous hemodynamic data, including heart rate (HR), mean arterial blood pressure (MBP), cardiac output by electrical velocimetry (COEV), arterial oxygen saturation, and renal (RrSO2) and cerebral (CrSO2) regional tissue oxygen saturation, were collected from 4 hours before the start of rewarming to 1 hour after the completion of rewarming. Serial echocardiography and transcranial Doppler were performed at 3 hours and 1 hour before the start of rewarming (T-3 and T-1; "baseline") and at 2, 4, and 7 hours after the start of rewarming (T+2, T+4, and T+7; "rewarming") to determine Cardiac output by echocardiography (COecho), stroke volume, fractional shortening, and middle cerebral artery (MCA) flow velocity indices. Repeated-measures analysis of variance was used for statistical analysis. Twenty infants with HIE were enrolled (mean gestational age, 38.8 ± 2 weeks; mean birth weight, 3346 ± 695 g). During rewarming, HR, COecho, and COEV increased from baseline to T+7, and MBP decreased. Despite an increase in fractional shortening, stroke volume remained unchanged. RrSO2 increased, and renal fractional oxygen extraction (FOE) decreased. MCA peak systolic flow velocity increased. There were no changes in CrSO2 or cerebral FOE. In neonates with HIE, CO significantly increases throughout rewarming. This is due to an increase in HR rather than stroke volume and is associated with an increase in renal blood flow. The lack of change in cerebral tissue oxygen saturation and extraction, in conjunction with an increase in MCA peak systolic velocity, suggests that cerebral flow metabolism coupling remained intact during rewarming.

Red Blood Cell Transfusions Affect Intestinal and Cerebral Oxygenation Differently in Preterm Infants with and without Subsequent Necrotizing Enterocolitis.

To assess intestinal and cerebral oxygenation during and after red blood cell (RBC) transfusions in preterms with or without subsequent transfusion-associated necrotizing enterocolitis (TANEC). In preterms of < 32 weeks' gestational age, we measured intestinal and cerebral regional tissue oxygen saturation (rintSO2, rcSO2) and their variabilities using near-infrared spectroscopy during and after transfusions. We compared eight infants who developed TANEC 6 to 48 hours after RBC transfusions with 16 controls. In TANEC infants, rcSO2 was lower during and after RBC transfusions than in controls, median (interquartile range) 55% (50-62) versus 72% (65-75), p < 0.01. There were no differences regarding rintSO2. Individual rintSO2 and rcSO2 ranges were smaller after transfusions in TANEC infants, 28% (9-36) versus 49% (40-65), p < 0.01, and 17% (14-33) versus 36% (26-57), p = 0.01, as was short-term rintSO2 variability. For each 10% higher rcSO2, the risk of developing TANEC decreased (odds ratio 0.09; 95% confidence interval 0.01-0.63). The smaller the rintSO2 range after transfusion, the higher the risk of developing TANEC. In preterm infants lower rcSO2, but not rintSO2, values during and after RBC transfusions are associated with TANEC. Lower rintSO2 and rcSO2 variabilities after RBC transfusions may represent a diminished capacity for vascular adaptation, possibly leading to TANEC.

RGB camera-based imaging of cerebral tissue oxygen saturation, hemoglobin concentration, and hemodynamic spontaneous low-frequency oscillations in rat brain following induction of cortical spreading depression.

To evaluate cerebral hemodynamics and spontaneous low-frequency oscillations (SLFOs) of cerebral blood flow in rat brain, we investigated an imaging method using a digital RGB camera. In this method, the RGB values were converted into tristimulus values in the CIE (Commission Internationale de l'Eclairage) XYZ color space, which is compatible with the common RGB working spaces. Monte Carlo simulation for light transport in tissue was then used to specify the relationship among the tristimulus XYZ values and the concentrations of oxygenated hemoglobin (CHbO), deoxygenated hemoglobin (CHbR), and total hemoglobin (CHbT) and cerebral tissue oxygen saturation (StO2). Applying the fast Fourier transform to each pixel of the sequential images of CHbT along the timeline, SLFOs of cerebral blood volume were visualized as a spatial map of power spectral density (PSD) at specific frequencies related to vasomotion. To confirm the feasibility of this method, we performed in vivo experiments using exposed rat brain during a cortical spreading depression (CSD) evoked by topical application of KCl. Cerebral hemodynamic responses to CSD such as initial hypoperfusion, profound hyperemia, and post-CSD oligemia and hypoxemia were successfully visualized with this method. At the transition to the hyperemia phase from hypoperfusion, CHbO and StO2 were significantly increased, which implied vasodilatation in arterioles and increased cerebral blood volume in response to CSD. In the wake of the hyperemic phase, CHbO and CHbT were significantly reduced to 25 ± 12% and 3.5 ± 1% of baseline, respectively, suggesting long-lasting vasoconstriction after CSD. In this persistent oligemia, StO2 significantly dropped to at most 23 ± 12% of the level before CSD, indicating long-lasting hypoxemia. The PSD value of SLFOs in CHbT for arteriole regions during CSD was significantly reduced to 28 ± 20% of baseline with respect to the pre-CSD level, which was correlated with the reduction in StO2. The results showed the possibility of RGB camera-based diffuse reflectance spectroscopy imaging for evaluating cerebral hemodynamics and SLFOs under normal and pathologic conditions.

Correlations between near-infrared spectroscopy, perfusion index, and cardiac outputs in extremely preterm infants in the first 72h of life.

CrSO2 and preductal PI are strongly correlated with cardiac output during low cardiac output states. What is Known: • Perfusion index and near-infrared spectroscopy are non-invasive tools to evaluate haemodynamics in preterm infants. • Pre- and postductal perfusion indexes strongly correlate with left ventricular output in term infants, and near-infrared spectroscopy has been validated to assess cerebral oxygenation in term and preterm infants. What is New: • Cerebral regional tissue oxygen saturation and preductal perfusion index were strongly correlated with cardiac output during low cardiac output states. • The strength of the correlation between cerebral regional tissue oxygen saturation, preductal perfusion index, and cardiac output varied in the first 72h of life, reflecting the complexity of the transitional physiology.

Physiology, intervention, and outcome: three critical questions about cerebral tissue oxygen saturation monitoring.

The balance between cerebral tissue oxygen consumption and supply can be continuously assessed by cerebral tissue oxygen saturation (SctO2) monitor. A construct consisting of three sequential questions, targeting the physiology monitored, the intervention implemented, and the outcomes affected, is proposed to critically appraise this monitor. The impact of the SctO2-guided care on patient outcome was examined through a systematic literature search and meta-analysis. We concluded that the physiology monitored by SctO2 is robust and dynamic, fragile (prone to derangement), and adversely consequential when deranged. The inter-individual variability of SctO2 measurement advocates for an intervention threshold based on a relative, not absolute, change. The intra-individual variability has multiple determinants which is the foundation of intervention. A variety of therapeutic options are available; however, none are 100% efficacious in treating cerebral dys-oxygenation. The therapeutic efficacy likely depends on both an appropriate differential diagnosis and the functional status of the regulatory mechanisms of cerebral blood flow. Meta-analysis based on five randomized controlled trials suggested a reduced incidence of early postoperative cognitive decline after major surgeries (RR= 0.53; 95% CI: 0.33-0.87; I2 =82%; P=0.01). However, its effects on other neurocognitive outcomes remain unclear. These results need to be interpreted with caution due to the high risks of bias. Quality RCTs based on improved intervention protocols and standardized outcome assessment are warranted in the future.