Cerebral Tissue Oxygenation Research Articles

Supine versus Prone Position during Delayed Cord Clamping in Infants ≥36 Weeks: A Randomized Trial.

There is no recommendation in the literature on optimal positioning of the newborn immediately at birth during delayed cord clamping. To evaluate if prone positioning on the mother's chest at birth during delayed cord clamping leads to a higher hematocrit at 30 hours of life compared to supine positioning. A randomized unblinded trial comparing prone and supine position of the newborn before umbilical cord clamping. Healthy newborns ≥36 weeks gestational age and born vaginally with cephalic presentation were included. The newborn was randomized to prone or supine position. Umbilical cord clamping was delayed in both groups to 1 minute after birth. The primary outcome was hematocrit at 30 hours of life. As a secondary outcome, cerebral tissue oxygenation (CrSO2) values were compared between both groups by near infrared spectroscopy. There was no difference in hematocrit at 30 hours of life between supine and prone positions with a mean at 52 and 53.1, respectively, mean difference -1.1 (95% confidence interval:-2.7, 0.5), p = 0.17. Newborns in supine and prone positions had comparable level of CrSO2 at 30 hours of life with a mean at 84.1 and 82.2, respectively, mean difference 1.9 (-0.2, 4.0), p = 0.07. There was no correlation between hematocrit and CrSO2 at 30 hours of life (r = 0.14). There was no difference between prone and supine positioning immediately after birth during delayed cord clamping on hematocrit at 30 hours of life. In the absence of clear findings, further studies with assessment of the effect of position on breastfeeding success in the case room, on maternal satisfaction and outcome beyond 30 hours are needed to make adequate recommendations on positioning. · Delayed cord clamping at 60 seconds is recommended at birth, but optimal positioning is unknown.. · A randomized trial was conducted to compare hematocrit at 36 hours of life of prone versus supine position.. · No difference in hematocrit was found in prone versus supine position during delayed cord clamping..

Association of intraoperative cerebral and somatic tissue oxygen saturation with postoperative acute kidney injury in adult patients undergoing multiple valve surgery

BackgroundThe association between tissue oxygenation with postoperative acute kidney injury (AKI) in adult patients undergoing multiple valve surgery has not been specifically studied.MethodsIn this prospective exploratory cohort study, 99 patients were enrolled. The left forehead, the left forearm, the left upper thigh, and the left renal region tissue oxygen saturation using near-infrared spectroscopy were monitored. The association between each threshold and AKI was assessed. The relative and absolute thresholds were < 70%, < 75%, < 80%, < 85%, < 90%, < 95%, and < 100% baseline, and baseline-standard deviation (SD), -1.5 SD, -2 SD, -2.5 SD, and -3 SD. Multivariate logistic regression analysis was adopted to explore the association.ResultsAKI occurred in 53 (54%) patients. The absolute value-based SrrO2 thresholds associated with AKI were baseline-3 SD (odds ratio [OR], 4.629; 95% confidence interval [CI], 1.238–17.314; P = 0.023) and baseline-2.5 SD (OR, 2.842; 95% CI, 1.025–7.881; P = 0.045) after adjusting for the potential confounders, those are renal region tissue oxygen saturation of 55% and 60%, but not statistically significant after correcting for multiple testing (corrected P = 0.114 and 0.179, respectively).ConclusionThe SrrO2 desaturation, defined as < baseline – 2.5 SD or < baseline – 3 SD, may be associated with AKI. The thresholds need to be verified in future large-scale studies.Trial registrationsThe study was registered at ClinicalTrials.gov, first trial registration: 26/10/2017, identifier: NCT03323203.

Ambulatory Monitoring of Cerebrovascular Responses to Upright Posture and Walking in Older Adults With Heart Failure

BackgroundInsufficient cardiac output in individuals with heart failure (HF) limits daily functioning and reduces quality of life. Although lower cerebral perfusion, secondary to limitations in cardiac output, has been observed during moderate-intensity efforts, individuals with HF also may be at risk for lower perfusion during even low-intensity ambulatory activities. MethodsWe determined whether HF is associated with an altered cerebrovascular response to low-intensity activities representative of typical challenges of daily living. In this study, we monitored central hemodynamics and middle cerebral artery blood velocity (MCAv) and cerebral tissue oxygenation (near-infrared spectroscopy) in 10 individuals with HF (aged 78 ± 4 years; left ventricular ejection fraction 20%-61%) and 13 similar-aged controls (79 ± 8 years; 52%–73%) during 3 randomized transitions, as follows: (i) supine-to-standing; (ii) sitting-to-slow-paced over-ground walking; and (iii) sitting-to-normal-paced over-ground walking. ResultsThroughout supine, sitting, standing, and both walking conditions, individuals with HF had lower cardiac index and cerebral tissue oxygenation than controls (P < 0.05), and MCAv was lower across the range of blood pressure in HF patients (P = 0.051) and during walking only (P = 0.011). Individuals with HF had an attenuated increase in stroke volume index and cardiac index during normal-paced walking, compared to controls (P < 0.01). ConclusionsThe indices of cerebral perfusion from MCAv and cerebral oxygenation were lower during ambulatory activities in individuals with HF; however, relationships between MCAv and blood pressure were not different between those with HF and controls, indicating no difference in static cerebral autoregulation.

Effect of electroacupuncture pretreatment on ferroptosis in neurons of rats with cerebral ischemia-reperfusion injury

To observe the effect of electroacupuncture（EA）preconditioning on ferroptosis in rats with cerebral ischemia-reperfusion injury （CIRI）, so as to explore the neuroprotective mechanism of EA preconditioning. Male SD rats were randomly divided into sham operation, model, EA, inhibitor and inducer groups with 20 rats in each group. The CIRI model was established by modified Zea Longa occlusion of the middle cerebral artery. Before modeling, EA treatment （2 Hz/15 Hz, 1-2 mA） was applied to "Baihui"（GV20）, "Fengfu"（GV16） and "Dazhui"（GV14） for rats of the EA group, 20 min a day for 7 consecutive days. Rats of the inhibitor group were intraperitoneally injected with ferristatin-1（25 mg/kg）at a slow and uniform rate. Rats of the inducer group were intraperitoneally injected with Erastin（100 mg/kg） after 7 days of EA preconditioning, once every 2 h for a total of 4 times. The CIRI models were prepared 2 d later after the above interventions finished by thread-occlusion. The degree of neurological impairment was evaluated by modified Zea Longa score. The percentage of infarct size was calculated by TTC staining. The ultrastructure of neurons in hippocampus was observed by transmission electron microscope. The contents of ferrous ion （Fe2+）, malondialdehyde （MDA） and glutathione （GSH） in cerebral tissue and reactive oxygen species （ROS） in serum were determined by biochemical method. The changes of mitochondrial membrane potential in rats brain tissues were detected by flow cytometry. The mRNA and protein expression levels of glutathione peroxidase 4 （GPX4）, acyl-CoA synthetase long-chain family member 4 （ACSL4）, transferrin receptor （TFRC）, 15-lipoxygenase （15-LOX） and cyclooxygenase-2 （COX-2） in the ischemic hippocampal region of CIRI rats were detected by real-time quantitative PCR and Western blot, respectively. Compared with the sham operation group, the neurological impairment score, the percentage of cerebral infarction area, the contents of MDA and Fe2+ in cerebral tissue as well as ROS in serum, the protein and mRNA expression levels of ACSL4, TFRC, 15-LOX, COX-2 in hippocampal tissue were increased （P<0.01）, while the content of GSH in cerebral tissue, the protein and mRNA expression levels of GPX4 in hippocampal tissue were decreased （P<0.01）, and mitochondria in brain tissue were significantly damaged （P<0.01） in the model group. Compared with the model group, the above indexes were all reversed （P<0.05, P<0.01） in the EA group and inhibitor group. Compared with the EA group, the neurological impairment score, the percentage of cerebral infarction area, the contents of MDA and Fe2+ in cerebral tissue as well as ROS in serum, the protein and mRNA expression le-vels of ACSL4, TFRC, 15-LOX, COX-2 in hippocampal tissue were increased （P<0.05, P<0.01）, while the content of GSH in cerebral tissue, the protein and mRNA expression levels of GPX4 in hippocampal tissue were decreased （P<0.01, P<0.05）, and mitochondria in brain tissue were significantly damaged （P<0.05） in the inducer group. EA preconditioning has neuroprotective effect on CIRI rats, which may be related to inhibiting ACSL4/TFRC/15-LOX/COX-2 expression and increasing GSH/GPX4 expression.

Relationship between cerebral oxygenation, cardiac output, and blood pressure during transitional period in extremely low gestational age neonates.

To describe the relationship between cerebral oxygenation, cardiac output, arterial blood pressure (BP), and cerebral blood flow velocity in extremely low gestational age neonates (ELGANs) during transition. This study comprises secondary analyses from a prospective observational study conducted at a tertiary Neonatal Intensive Care Unit. Recruited ELGANs underwent cerebral saturation (CrSO2) monitoring and serial echocardiography during 72 h from birth. Correlative analyses of CrSO2 and cerebral fractional tissue oxygen extraction (CFTOE) with left (LVO) and right ventricular output (RVO), superior vena cava (SVC) flow, middle cerebral artery blood flow mean velocity (MCA.MV), systolic (SBP), diastolic (DBP), and mean (MBP) BP were conducted. Fifty ELGANs with median (range) gestational age of 25.9 (23.1-27.9) weeks were recruited. Echocardiography was performed sequentially at a median (range) age 5.0 (3.8-6.6), 17.3 (15.4-19.4), 31.0 (27.0-34.1), and 53.7 (49.3-58.3) hours. RVO, LVO, CrSO2, and SBP increased over time but no changes in MBP, DBP, CFTOE, MCA.MV or SVC flow were noted. A weak correlation was identified between CrSO2 and SBP (r2 = 0.11, p = 0.047) and MBP (r2 = 0.12, p = 0.04) at 17.3 (15.4-19.4) hours. No correlation of either CrSO2 or CFTOE with any measures of blood flow was identified. There is a weak correlation between measures of cardiac output, BP, and MCA.MV with both CrSO2 and CFTOE in ELGANs during transition. Whether this finding suggests intact cerebral autoregulation requires prospective evaluation in a cohort of sick ELGANs.

The impact of central and obstructive respiratory events on cerebral oxygenation in adults with sleep disordered breathing

Obstructive sleep apnea (OSA) and central sleep apnea (CSA) are two main types of sleep disordered breathing (SDB). While the changes in cerebral hemodynamics triggered by OSA events have been well studied using near-infrared spectroscopy (NIRS), they are essentially unknown in CSA in adults. Therefore, in this study, we compared the changes in cerebral oxygenation between OSA and CSA events in adult patients using NIRS. Cerebral tissue oxygen saturation (StO2) in 13 severe SDB patients who had both CSA and OSA events was measured using frequency-domain NIRS. The changes in cerebral StO2 desaturation and blood volume (BV) in the first hour of natural sleep were compared between different types of respiratory events (i.e., 277 sleep hypopneas, 161 OSAs and 113 CSAs) with linear mixed-effect models controlling for confounders. All respiratory events occurred during non-rapid eye movement (NREM) sleep. We found that apnea events induced greater cerebral desaturations and BV fluctuations compared to hypopneas, but there was no difference between OSA and CSA. These results suggest that cerebral autoregulation in our patients are still capable to counteract the pathomechanisms of apneas, in particularly the negative intrathoracic pressure (ITP) caused by OSA events. Otherwise larger BV fluctuations in OSA compared to CSA should be observed due to the negative ITP that reduces cardiac stroke volume and leads to lower systematic blood supply. Our study suggests that OSA and CSA may have similar impact on cerebral oxygenation during NREM sleep in adult patients with SDB.

Association of cerebral metabolic rate following therapeutic hypothermia with 18-month neurodevelopmental outcomes after neonatal hypoxic ischemic encephalopathy.

Therapeutic hypothermia (TH) is standard of care for moderate to severe neonatal hypoxic ischemic encephalopathy (HIE) but many survivors still suffer lifelong disabilities and benefits of TH for mild HIE are under active debate. Development of objective diagnostics, with sensitivity to mild HIE, are needed to select, guide, and assess response to treatment. The objective of this study was to determine if cerebral oxygen metabolism (CMRO2) in the days after TH is associated with 18-month neurodevelopmental outcomes as the first step in evaluating CMRO2's potential as a diagnostic for HIE. Secondary objectives were to compare associations with clinical exams and characterise the relationship between CMRO2 and temperature during TH. This was a prospective, multicentre, observational, cohort study of neonates clinically diagnosed with HIE and treated with TH recruited from the tertiary neonatal intensive care units (NICUs) of Boston Children's Hospital, Brigham and Women's Hospital, and Beth Israel Deaconess Medical Center between December 2015 and October 2019 with follow-up to 18 months. In total, 329 neonates ≥34 weeks gestational age admitted with perinatal asphyxia and suspected HIE were identified. 179 were approached, 103 enrolled, 73 received TH, and 64 were included. CMRO2 was measured at the NICU bedside by frequency-domain near-infrared and diffuse correlation spectroscopies (FDNIRS-DCS) during the late phases of hypothermia (C), rewarming (RW) and after return to normothermia (NT). Additional variables were body temperature and clinical neonatal encephalopathy (NE) scores, as well as findings from magnetic resonance imaging (MRI) and spectroscopy (MRS). Primary outcome was the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) at 18 months, normed (SD) to 100 (15). Data quality for 58 neonates was sufficient for analysis. CMRO2 changed by 14.4% per °C (95% CI, 14.2-14.6) relative to its baseline at NT while cerebral tissue oxygen extraction fraction (cFTOE) changed by only 2.2% per °C (95% CI, 2.1-2.4) for net changes from C to NT of 91% and 8%, respectively. Follow-up data for 2 were incomplete, 33 declined and 1 died, leaving 22 participants (mean [SD] postnatal age, 19.1 [1.2] month; 11 female) with mild to moderate HIE (median [IQR] NE score, 4 [3-6]) and 21 (95%) with BSID-III scores >85at 18 months. CMRO2 at NT was positively associated with cognitive and motor composite scores (β (SE)=4.49 (1.55) and 2.77 (1.00) BSID-III points per 10-10moL/dl×mm2/s, P=0.009 and P=0.01 respectively; linear regression); none of the other measures were associated with the neurodevelopmental outcomes. Point of care measures of CMRO2 in the NICU during C and RW showed dramatic changes and potential to assess individual response to TH. CMRO2 following TH outperformed conventional clinical evaluations (NE score, cFTOE, and MRI/MRS) at predicting cognitive and motor outcomes at 18 months for mild to moderate HIE, providing a promising objective, physiologically-based diagnostic for HIE. This clinical study was funded by an NIH grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, United States (R01HD076258).

Insights into Neonatal Cerebral Autoregulation by Blood Pressure Monitoring and Cerebral Tissue Oxygenation: A Qualitative Systematic Review.

The aim of this qualitative systematic review was to identify publications on blood pressure monitoring in combination with cerebral tissue oxygenation monitoring during the first week after birth focusing on cerebral autoregulation. A systematic search was performed on PubMed. The following search terms were used: infants/newborn/neonates, blood pressure/systolic/diastolic/mean/MAP/SAP/DAP, near-infrared spectroscopy, oxygenation/saturation/oxygen, and brain/cerebral. Additional studies were identified by a manual search of references in the retrieved studies and reviews. Only human studies were included. Thirty-one studies focused on preterm neonates, while five included preterm and term neonates. In stable term neonates, intact cerebral autoregulation was shown by combining cerebral tissue oxygenation and blood pressure during immediate transition, while impaired autoregulation was observed in preterm neonates with respiratory support. Within the first 24 h, stable preterm neonates had reduced cerebral tissue oxygenation with intact cerebral autoregulation, while sick neonates showed a higher prevalence of impaired autoregulation. Further cardio-circulatory treatment had a limited effect on cerebral autoregulation. Impaired autoregulation, with dependency on blood pressure and cerebral tissue oxygenation, increased the risk of intraventricular hemorrhage and abnormal neurodevelopmental outcomes. Integrating blood pressure monitoring with cerebral tissue oxygenation measurements has the potential to improve treatment decisions and optimizes neurodevelopmental outcomes in high-risk neonates.

Differences between Hepatic and Cerebral Regional Tissue Oxygen Saturation at the Onset of Intradialytic Hypotension.

Intradialytic hypotension (IDH) is a critical pathological condition associated with all-cause mortality in patients undergoing hemodialysis (HD). However, few studies have investigated IDH-related changes in hepatic and cerebral regional tissue oxygen saturation (rSO2). This study investigated IDH-induced changes in hepatic and cerebral rSO2. Hepatic and cerebral rSO2 during HD were measured using an INVOS 5100C oxygen saturation monitor, and their percentage (%) changes during the development of IDH were analyzed. Ninety-one patients undergoing HD were investigated, including twenty with IDH. In patients with IDH, % changes in hepatic and cerebral rSO2 decreased at the onset of IDH. Additionally, the % change in hepatic rSO2 was significantly larger than that in cerebral rSO2 (p < 0.001). In patients without IDH, no significant differences were found between the % changes in hepatic and cerebral rSO2 at the time of the lowest systolic blood pressure during HD. Multivariable linear regression analysis showed that the difference between the % changes in cerebral and hepatic rSO2 was significantly associated with the development of IDH (p < 0.001) and the ultrafiltration rate (p = 0.010). Hepatic and cerebral rSO2 significantly decreased during the development of IDH, and hepatic rSO2 was more significantly decreased than cerebral rSO2 at the onset of IDH.

The Diagnostic Value of Near-Infrared Spectroscopy to Predict Delayed Cerebral Ischemia and Unfavorable Outcome After Subarachnoid Hemorrhage

Near-infrared spectroscopy (NIRS) is a noninvasive tool to monitor cerebral regional oxygen saturation. Impairment of microvascular circulation with subsequent cerebral hypoxia during delayed cerebral ischemia (DCI) is associated with poor functional outcome after subarachnoid hemorrhage (SAH). Therefore, NIRS could be useful to predict the risk for DCI and functional outcome. However, only limited data are available on NIRS regional cerebral tissue oxygen saturation (rSO2) distribution in SAH. The aim of this study was to compare the distribution of NIRS rSO2 values in patients with nontraumatic SAH with the occurrence of DCI and functional outcome at 2 months. In addition, the predictive value of NIRS rSO2 was compared with the previously validated SAFIRE grade (derived from Size of the aneurysm, Age, FIsher grade, World Federation of Neurosurgical Societies after REsuscitation). In this study, the rSO2 distribution of patients with and without DCI after SAH was compared. The optimal cutoff points to predict DCI and outcome were assessed, and its predictive value was compared with the SAFIRE grade. Of 41 patients, 12 developed DCI, and 9 had unfavorable outcome at 60 days. Prediction of DCI with NIRS had an area under the curve of 0.77 (95% confidence interval 0.62-0.92; P= 0.0028) with an optimal cutoff point of 65% (sensitivity 1.00; specificity 0.45). Prediction of favorable outcome with NIRS had an area under the curve of 0.86 (95% confidence interval 0.74-0.98; P= 0.0003) with an optimal cutoff point of 63% (sensitivity 1.00; specificity 0.63). Regression analysis showed that NIRS rSO2 score is complementary to the SAFIRE grade. NIRS rSO2 monitoring in patients with SAH may improve prediction of DCI and clinical outcome after SAH.

A large arteriovenous fistula steals a considerable part of systemic blood flow during veno-arterial extracorporeal circulation support in a porcine model.

Background: Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is one of the most frequently used mechanical circulatory support devices. Distribution of extracorporeal membrane oxygenation flow depends (similarly as the cardiac output distribution) on regional vascular resistance. Arteriovenous fistulas (AVFs), used frequently as hemodialysis access, represent a low-resistant circuit which steals part of the systemic perfusion. We tested the hypothesis that the presence of a large Arteriovenous fistulas significantly changes organ perfusion during a partial and a full Veno-arterial extracorporeal membrane oxygenation support. Methods: The protocol was performed on domestic female pigs held under general anesthesia. Cannulas for Veno-arterial extracorporeal membrane oxygenation were inserted into femoral artery and vein. The Arteriovenous fistulas was created using another two high-diameter extracorporeal membrane oxygenation cannulas inserted in the contralateral femoral artery and vein. Catheters, flow probes, flow wires and other sensors were placed for continuous monitoring of haemodynamics and organ perfusion. A stepwise increase in extracorporeal membrane oxygenation flow was considered under beating heart and ventricular fibrillation (VF) with closed and opened Arteriovenous fistulas. Results: Opening of a large Arteriovenous fistulas (blood flow ranging from 1.1 to 2.2L/min) resulted in decrease of effective systemic blood flow by 17%-30% (p < 0.01 for all steps). This led to a significant decrease of carotid artery flow (ranging from 13% to 25% after Arteriovenous fistulas opening) following VF and under partial extracorporeal membrane oxygenation support. Cerebral tissue oxygenation measured by near infrared spectroscopy also decreased significantly in all steps. These changes occurred even with maintained perfusion pressure. Changes in coronary artery flow were driven by changes in the native cardiac output. Conclusion: A large arteriovenous fistula can completely counteract Veno-arterial extracorporeal membrane oxygenation support unless maximal extracorporeal membrane oxygenation flow is applied. Cerebral blood flow and oxygenation are mainly compromised by the effect of the Arteriovenous fistulas. These effects could influence brain function in patients with Arteriovenous fistulas on Veno-arterial extracorporeal membrane oxygenation.

Fluctuations in Oxygen Saturation during Synchronized Nasal Intermittent Positive Pressure Ventilation and Nasal High-Frequency Oscillatory Ventilation in Very Low Birth Weight Infants: A Randomized Crossover Trial

Background: Very low birth weight (VLBW) infants on noninvasive ventilation (NIV) experience frequent fluctuations in oxygen saturation (SpO₂) that are associated with an increased risk for mortality and severe morbidities. Methods: In this randomized crossover trial, VLBW infants (n = 22) born 22+3 to 28+0 weeks on NIV with supplemental oxygen were allocated on two consecutive days in random order to synchronized nasal intermittent positive pressure ventilation (sNIPPV) and nasal high-frequency oscillatory ventilation (nHFOV) for 8 h. nHFOV and sNIPPV were set to equivalent mean airway pressure and transcutaneous pCO₂. Primary outcome was the time spent within the SpO₂ target (88–95%). Results: During sNIPPV, VLBW infants spent significantly more time within the SpO₂ target (59.9%) than during nHFOV (54.6%). The proportion of time spent in hypoxemia (22.3% vs. 27.1%) and the mean fraction of supplemental oxygen (FiO₂) (29.4% vs. 32.8%) were significantly reduced during sNIPPV, while the respiratory rate (50.1 vs. 42.6) was significantly higher. Mean SpO₂, SpO₂ above the target, number of prolonged (>1 min) and severe (SpO₂ <80%) hypoxemic episodes, parameters of cerebral tissue oxygenation using NIRS, number of FiO₂ adjustments, heart rate, number of bradycardias, abdominal distension and transcutaneous pCO₂ did not differ between both interventions. Conclusions: In VLBW infants with frequent fluctuations in SpO₂, sNIPPV is more efficient than nHFOV to retain the SpO₂ target and to reduce FiO₂ exposure. These results demand more detailed investigations into cumulative oxygen toxicities during different modes of NIV over the weaning period, particularly with regard to consequences for long-term outcomes.

PEMENUHAN KEBUTUHAN OKSIGENASI DENGAN PEMBERIAN POSISI HEAD UP 30˚ PADA PASIEN STROKE

Stroke as cerebrovascular damage, is a loss of brain function caused by cessation or reduced blood supply to an area of the brain, resulting in local or global neurological dysfunction. Substandard blood flow in stroke patients can lead to hemodynamic abnormalities, where hemodynamic conditions affect the distribution of oxygen throughout the body, affect heart function and reduce oxygen saturation so that stroke is an emergency case and requires fast and appropriate help. Purpose: of this study was to determine how to fulfill the need for oxygenation by giving a 30˚ head up position in stroke patients. Method: used is a literature study or literature review using articles/journals in the form of fulfilling oxygen needs by giving a 30˚ head up position in stroke patients. Results: showed that there was a significant increase in oxygen saturation levels after the 30˚ head up position in stroke patients. Conclusion :of this study is that one of the interventions that can be carried out in fulfilling oxygenation in stroke patients is giving a 30 head up position with a head elevation or 30˚ head up position that can facilitate increased cerebral blood flow and maximize cerebral tissue oxygenation

The oxygen reactivity index indicates disturbed local perfusion regulation after aneurysmal subarachnoid hemorrhage: an observational cohort study

BackgroundCerebral autoregulation (CA) can be impaired in patients with delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The Pressure Reactivity Index (PRx, correlation of blood pressure and intracranial pressure) and Oxygen Reactivity Index (ORx, correlation of cerebral perfusion pressure and brain tissue oxygenation, PbtO2) are both believed to estimate CA. We hypothesized that CA could be poorer in hypoperfused territories during DCI and that ORx and PRx may not be equally effective in detecting such local variances.MethodsORx and PRx were compared daily in 76 patients with aSAH with or without DCI until the time of DCI diagnosis. The ICP/PbtO2-probes of DCI patients were retrospectively stratified by being in or outside areas of hypoperfusion via CT perfusion image, resulting in three groups: DCI + /probe + (DCI patients, probe located inside the hypoperfused area), DCI + /probe− (probe outside the hypoperfused area), DCI− (no DCI).ResultsPRx and ORx were not correlated (r = − 0.01, p = 0.56). Mean ORx but not PRx was highest when the probe was located in a hypoperfused area (ORx DCI + /probe + 0.28 ± 0.13 vs. DCI + /probe− 0.18 ± 0.15, p < 0.05; PRx DCI + /probe + 0.12 ± 0.17 vs. DCI + /probe− 0.06 ± 0.20, p = 0.35). PRx detected poorer autoregulation during the early phase with relatively higher ICP (days 1–3 after hemorrhage) but did not differentiate the three groups on the following days when ICP was lower on average. ORx was higher in the DCI + /probe + group than in the other two groups from day 3 onward. ORx and PRx did not differ between patients with DCI, whose probe was located elsewhere, and patients without DCI (ORx DCI + /probe− 0.18 ± 0.15 vs. DCI− 0.20 ± 0.14; p = 0.50; PRx DCI + /probe− 0.06 ± 0.20 vs. DCI− 0.08 ± 0.17, p = 0.35).ConclusionsPRx and ORx are not interchangeable measures of autoregulation, as they likely measure different homeostatic mechanisms. PRx represents the classical cerebrovascular reactivity and might be better suited to detect disturbed autoregulation during phases with moderately elevated ICP. Autoregulation may be poorer in territories affected by DCI. These local perfusion disturbances leading up to DCI may be more readily detected by ORx than PRx. Further research should investigate their robustness to detect DCI and to serve as a basis for autoregulation-targeted treatment after aSAH.

A short session of maternal hyperoxygenation ameliorates the cerebral oxygenation difference between fetuses with and without congenital heart defects

ObjectivesTo assess if a 10 min session of maternal hyperoxygenation increases cerebral tissue oxygenation as measured by magnetic resonance imaging (MRI) T2* in fetuses with and without congenital heart defects (CHDs). Study designAt mean gestational ages of 32 (early) and 37 (late), we measured fetal cerebral T2* before and during the last minutes of a 10 min maternal hyperoxygenation (oxygen 10 l/min, Hudson non-rebreathing mask) in 22 fetuses without CHDs and 11 fetuses with CHDs using a 1.5 Tesla Philips scanner with a breath-hold, multi-echo, gradient-echo sequence. ResultsDuring maternal hyperoxygenation equilibrium, the mean fetal cerebral T2* values in CHD fetuses seemingly normalized and were comparable to those in fetuses without CHD breathing ambient air. Hyperoxygenation T2* was 160 ms (CI 149–170) early and 123 ms (CI 112–134) late in fetuses with CHD and ambient air T2* was 158 ms (CI 152 to 164) early and 126 ms (CI 120–131) late in fetuses without CHD, (p=0.97). Lower ambient air cerebral T2* z-score at the late-stage scan was correlated with lower head circumference z-scores at birth. ConclusionOur findings suggest that fetal cerebral oxygenation in CHD fetuses can reach normal values during a short session of maternal hyperoxygenation. This supports the hypothesis that tissue hypoxia can influence brain development in fetuses with CHD. However, since side effects of fetal hyperoxygenation have been described, it remains to be determined if chronic maternal hyperoxygenation has a positive impact on the fetal brain in CHDs.

Brain hypoxia, neurocognitive impairment, and quality of life in people post-COVID-19

ObjectiveSystemic hypoxia occurs in COVID-19 infection; however, it is unknown if cerebral hypoxia occurs in convalescent individuals. We have evidence from other conditions associated with central nervous system inflammation that hypoxia may occur in the brain. If so, hypoxia could reduce the quality of life and brain function. This study was undertaken to assess if brain hypoxia occurs in individuals after recovery from acute COVID-19 infection and if this hypoxia is associated with neurocognitive impairment and reduced quality of life.MethodsUsing frequency-domain near-infrared spectroscopy (fdNIRS), we measured cerebral tissue oxygen saturation (StO2) (a measure of hypoxia) in participants who had contracted COVID-19 at least 8 weeks prior to the study visit and healthy controls. We also conducted neuropsychological assessments and health-related quality of life assessments, fatigue, and depression.ResultsFifty-six percent of the post-COVID-19 participants self-reported having persistent symptoms (from a list of 18), with the most reported symptom being fatigue and brain fog. There was a gradation in the decrease of oxyhemoglobin between controls, and normoxic and hypoxic post-COVID-19 groups (31.7 ± 8.3 μM, 27.8 ± 7.0 μM and 21.1 ± 7.2 μM, respectively, p = 0.028, p = 0.005, and p = 0.081). We detected that 24% of convalescent individuals’ post-COVID-19 infection had reduced StO2 in the brain and that this relates to reduced neurological function and quality of life.InterpretationWe believe that the hypoxia reported here will have health consequences for these individuals, and this is reflected in the correlation of hypoxia with greater symptomology. With the fdNIRS technology, combined with neuropsychological assessment, we may be able to identify individuals at risk of hypoxia-related symptomology and target individuals that are likely to respond to treatments aimed at improving cerebral oxygenation.

Position Head Up Towards Reduction of Blood Pressure in Non-Hemoragic Stroke Patients in The Inpatient Room of Harapan Insan Sendawar Hospital

Introduction: position Head up 30º is a position given to stroke patients to improve blood flow to the heart. brain and maximize cerebral tissue oxygenation. Objective: This study aims to determine the effect of head up 30º to decrease blood pressure in non-hemorrhagic stroke patients. Methods: research quasi-experimental approach pre and post without control. The population is 32 people. The sample is 15 people using accidental sampling technique. The research site is in HIS Hospital. The instruments used are SOP, sphygmomanometer, and observation sheet. Collecting data obtained from primary data. Data were analyzed bivariately using paired sample t statistic test. Results and Discussion: The results of the statistical test paired t sample p value are 0.000 &lt;0.05, which means Ha is accepted that there is an effect of giving a head-up to the decrease in blood pressure of stroke patients in the inpatient room at Harapan Insan Sendawar Hospital. Conclusion: There is an effect of giving a head up on the blood pressure of stroke patients at Harapan Insan Sendawar Hospital. It is recommended for the hospital to intervene in a head up in stroke patients

PREHOSPITAL PLASMA IS NONINFERIOR TO WHOLE BLOOD FOR RESTORATION OF CEREBRAL OXYGENATION IN A RHESUS MACAQUE MODEL OF TRAUMATIC SHOCK AND HEMORRHAGE.

Introduction: Traumatic shock and hemorrhage (TSH) is a leading cause of preventable death in military and civilian populations. Using a TSH model, we compared plasma with whole blood (WB) as prehospital interventions, evaluating restoration of cerebral tissue oxygen saturation (CrSO 2 ), systemic hemodynamics, colloid osmotic pressure (COP) and arterial lactate, hypothesizing plasma would function in a noninferior capacity to WB, despite dilution of hemoglobin (Hgb). Methods: Ten anesthetized male rhesus macaques underwent TSH before randomization to receive a bolus of O(-) WB or AB(+) plasma at T0. At T60, injury repair and shed blood (SB) to maintain MAP > 65 mm Hg began, simulating hospital arrival. Hematologic data and vital signs were analyzed via t test and two-way repeated measures ANOVA, data presented as mean ± SD, significance = P < 0.05. Results: There were no significant group differences for shock time, SB volume, or hospital SB. At T0, MAP and CrSO 2 significantly declined from baseline, though not between groups, normalizing to baseline by T10. Colloid osmotic pressure declined significantly in each group from baseline at T0 but restored by T30, despite significant differences in Hgb (WB 11.7 ± 1.5 vs. plasma 6.2 ± 0.8 g/dL). Peak lactate at T30 was significantly higher than baseline in both groups (WB 6.6 ± 4.9 vs. plasma 5.7 ± 1.6 mmol/L) declining equivalently by T60. Conclusions: Plasma restored hemodynamic support and CrSO 2 , in a capacity not inferior to WB, despite absence of additional Hgb supplementation. This was substantiated via return of physiologic COP levels, restoring oxygen delivery to microcirculation, demonstrating the complexity of restoring oxygenation from TSH beyond simply increasing oxygen carrying capacity.

Preterm infants variability in cerebral near-infrared spectroscopy measurements in the first 72-h after birth.

Cerebral near-infrared spectroscopy is a non-invasive tool used to measure regional cerebral tissue oxygenation (rScO2) initially validated in adult and pediatric populations. Preterm neonates, vulnerable to neurologic injury, are attractive candidates for NIRS monitoring; however, normative data and the brain regions measured by the current technology have not yet been established for this population. This study's aim was to analyze continuous rScO2 readings within the first 6-72 h after birth in 60 neonates without intracerebral hemorrhage born at ≤1250 g and/or ≤30 weeks' gestational age (GA) to better understand the role of head circumference (HC) and brain regions measured. Using a standardized brain MRI atlas, we determined that rScO2 in infants with smaller HCs likely measures the ventricular spaces. GA is linearly correlated, and HC is non-linearly correlated, with rScO2 readings. For HC, we infer that rScO2 is lower in infants with smaller HCs due to measuring the ventricular spaces, with values increasing in the smallest HCs as the deep cerebral structures are reached. Clinicians should be aware that in preterm infants with small HCs, rScO2 displayed may reflect readings from the ventricular spaces and deep cerebral tissue. Clinicians should be aware that in preterm infants with small head circumferences, cerebral near-infrared spectroscopy readings of rScO2 displayed may reflect readings from the ventricular spaces and deep cerebral tissue. This highlights the importance of rigorously re-validating technologies before extrapolating them to different populations. Standard rScO2 trajectories should only be established after determining whether the mathematical models used in NIRS equipment are appropriate in premature infants and the brain region(s) NIRS sensors captures in this population, including the influence of both gestational age and head circumference.

Induced Blood Flow Oscillations at 0.1 Hz Protects Oxygenation of Severely Ischemic Tissue

Background: Early interventions that improve vital organ perfusion will reduce the number of lives lost from blood loss injuries. We have shown that generating 10 second (~0.1 Hz) fluctuations or “oscillations” in arterial pressure and blood flow during simulated hemorrhage protects cerebral tissue oxygenation. Lower body negative pressure (LBNP) was used to both simulate hemorrhage, and induce the hemodynamic oscillations in these previous studies. However, the magnitude of cerebral tissue ischemia is limited to 20-30% with LBNP due to the onset of pre-syncopal symptoms. To examine the effect of 0.1 Hz hemodynamic oscillations on blood flow delivery and tissue oxygenation of severely ischemic tissues, we developed a limb ischemia model. Hypothesis: Oscillatory arterial pressure and blood flow will attenuate reductions in brachial artery blood flow and forearm tissue oxygenation in a severely ischemic limb. Methods: Nine healthy human subjects (5M, 4F; 27.2 ± 4.1 y) completed two experimental protocols separated by ≥48 h. In both conditions, ischemia of the forearm was induced with a pneumatic cuff on the upper arm to decrease brachial artery (BA) blood velocity by ~70-80% from baseline. In the oscillation condition (OSC), 0.1 Hz oscillations in mean arterial pressure (MAP) and BA blood flow were then induced by inflating and deflating bilateral thigh cuffs every 10 seconds (0.1 Hz) throughout the forearm ischemia period. In the control condition (CON), the thigh cuffs were in place, but were inactive throughout the forearm ischemia period. BA blood flow was measured via duplex ultrasound, forearm muscle tissue oxygenation (SmO2) was measured via near infrared spectroscopy, and arterial pressure was measured via finger photoplethysmography. Results: The magnitude of forearm ischemia, indexed by the reduction in BA blood velocity, was matched between protocols (CON: -75.2 ± 8.4 % vs. OSC: -78.3 ± 7.8 %, p=0.20). Power spectral density of 0.1 Hz oscillations in MAP (CON: 19.4 ± 22.8 mmHg2 vs. OSC: 716.8 ± 514.6 mmHg2; p&lt;0.001) and BA blood velocity (CON: 0.7 ± 1.0 cm/s2 vs. OSC: 10.6 ± 7.1 cm/s2, p=0.02) were greater with oscillatory thigh cuff compression compared with the control condition. While oscillatory thigh cuff compression during forearm ischemia had no effect on absolute MAP (CON: 94.3 ± 6.6 mmHg vs. OSC: 94.4 ± 10.8 mmHg, p=0.99), BA blood flow (CON: 9.7 ± 5.8 ml/min vs. OSC: 9.5 ± 7.3 ml/min, p=0.82), or BA conductance (CON: 0.10 ± 0.06 ml/min/mmHg vs. OSC: 0.09 ± 0.06 ml/min/mmHg, p=0.39), the reduction in SmO2 was attenuated (CON: -38.7 ± 8.3 % vs. OSC: -28.4 ± 9.7 %; p=0.04). These data provide further evidence for the use of 0.1 Hz hemodynamic oscillations as a therapeutic intervention for conditions associated with severe vital organ ischemia such as hemorrhage, stroke, myocardial infarction, and sepsis. National Institutes of Health/National Institute on Aging T32 Ruth Kirschstein Institutional National Research Service Award (T32AG020494); American Heart Association Transformational Project Award (19TPA34910073) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.