Decrease In Cerebral Oxygenation Research Articles

A Quantitative Assessment of Cerebral Hemodynamic Perturbations Associated with Long R-R Intervals in Atrial Fibrillation: A Pilot-Case-Based Experience.

Background and Objectives: Atrial fibrillation (AF) results in systemic hemodynamic perturbations which impact cerebral circulation, possibly contributing to the development of dementia. However, evidence documenting effects in cerebral perfusion is scarce. The aim of this study is to provide a quantitative characterization of the magnitude and time course of the cerebral hemodynamic response to the short hypotensive events associated with long R-R intervals, as detected by near-infrared spectroscopy (NIRS). Materials and Methods: Cerebral NIRS signals and arterial blood pressure were continuously recorded along with an electrocardiogram in twelve patients with AF undergoing elective electrical cardioversion (ECV). The top 0.5-2.5% longest R-R intervals during AF were identified in each patient and used as triggers to carry out the triggered averaging of hemodynamic signals. The average curves were then characterized in terms of the latency, magnitude, and duration of the observed effects, and the possible occurrence of an overshoot was also investigated. Results: The triggered averages revealed that long R-R intervals produced a significant drop in diastolic blood pressure (-13.7 ± 6.1 mmHg) associated with an immediate drop in cerebral blood volume (THI: -0.92 ± 0.46%, lasting 1.9 ± 0.8 s), followed by a longer-lasting decrease in cerebral oxygenation (TOI: -0.79 ± 0.37%, lasting 5.2 ± 0.9 s, p < 0.01). The recovery of the TOI was generally followed by an overshoot (+1.06 ± 0.12%). These effects were progressively attenuated in response to R-R intervals of a shorter duration. Conclusions: Long R-R intervals cause a detectable and consistent cerebral hemodynamic response which concerns both cerebral blood volume and oxygenation and outlasts the duration of the systemic perturbation. These effects are compatible with the activation of dynamic autoregulatory mechanisms in response to the hypotensive stimulus.

Cocoa flavanols protect cognitive function, cerebral oxygenation, and mental fatigue during severe hypoxia.

We tested the hypothesis that ingestion of cocoa flavanols would improve cognition during acute hypoxia equivalent to 5,500 m altitude (partial pressure of end-tidal oxygen = 45 mmHg). Using placebo-controlled double-blind trials, 12 participants ingested 15 mg·kg-1 of cocoa flavanols 90 min before completing cognitive tasks during normoxia and either poikilocapnic or isocapnic hypoxia (partial pressure of end-tidal carbon dioxide uncontrolled or maintained at the baseline value, respectively). Cerebral oxygenation was measured using functional near-infrared spectroscopy. Overall cognition was impaired by poikilocapnic hypoxia (main effect of hypoxia, P = 0.008). Cocoa flavanols improved a measure of overall cognitive performance by 4% compared with placebo (effect of flavanols, P = 0.033) during hypoxia, indicating a change in performance from "low average" to "average." The hypoxia-induced decrease in cerebral oxygenation was two-fold greater with placebo than with cocoa flavanols (effect of flavanols, P = 0.005). Subjective fatigue was increased by 900% with placebo compared with flavanols during poikilocapnic hypoxia (effect of flavanols, P = 0.004). Overall cognition was impaired by isocapnic hypoxia (effect of hypoxia, P = 0.001) but was not improved by cocoa flavanols (mean improvement = 1%; effect of flavanols, P = 0.72). Reaction time was impaired by 8% with flavanols during normoxia and further impaired by 11% during isocapnic hypoxia (effect of flavanols, P = 0.01). Our findings are the first to show that flavanol-mediated improvements in cognition and mood during normoxia persist during severe oxygen deprivation, conferring a neuroprotective effect.NEW & NOTEWORTHY We show for the first time that cocoa flavanols exert a neuroprotective effect during severe hypoxia. Following acute cocoa flavanol ingestion, we observed improvements in cognition, cerebral oxygenation, and subjective fatigue during normoxia and severe poikilocapnic hypoxia. Cocoa flavanols did not improve cognition during severe isocapnic hypoxia, suggesting a possible interaction with carbon dioxide.

Predictors of the development of cognitive impairment in patients undergoing pulmonary thromboendarterectomy

Aim: To study the clinical and functional features, as well as intra- and postoperative indicators of patients with chronic thromboembolic pulmonary hypertension (CTEPH) with the development of negative dynamics of cognitive status in the early postoperative period and to identify pathophysiological factors associated with this disorder.Material and Methods. The study included patients with CTEPH scheduled for pulmonary endarterectomy (PEA). The 1st group (38 people) consisted of patients with the development of negative dynamics of cognitive functions according to the MMSE scale in the early postoperative period, the 2nd group (91 people) – without negative dynamics of cognitive functions. Preoperative clinical, anamnestic data, intraoperative parameters, early postoperative complications and their relationship with the negative postoperative dynamics of cognitive status were analyzed.Results. The average age of patients in the general group was 54.1 (44.3–68.1) years. The 1st group was characterized by older age (p = 0.03), a prevalence of patients with diabetes mellitus (p = 0.02), arterial hypertension (p = 0.04), atherosclerosis of the brachiocephalic arteries ≤ 50% (p = 0.04) and higher level of Charlesson comorbidity index (p = 0.002) in comparison with the 2nd group. Intraoperative factors for the development of postoperative cognitive impairment were a longer circulatory arrest (CA) during PEA and a more pronounced decrease in cerebral oxygenation during CA. The 1st group of patients were characterized by a large number of complications, including pulmonary heart failure (p = 0.02), acute renal failure (p &lt; 0.001) and atrial fibrillation (p &lt; 0.001) in comparison with the 2nd group. The development of negative postoperative dynamics of cognitive status in CTEPH patients was associated with baseline reduced cognitive function – OR 2.3 (1.4–9.2 95% CI) (p = 0.01) and with the presence of three or more CA during PEA – OR 3.2 (1.1–12.7 95% CI) (p = 0.01).Conclusion. Independent factors for the development of negative postoperative dynamics of cognitive status in patients with CTEPH were baseline impairment of cognitive function (&lt; 20 points according to the MMSE scale), three or more CA during PEA, and the development of new-onset atrial fibrillation in the early postoperative period.

A cervical compartment syndrome impairs cerebral circulation in post-thyroidectomy hemorrhage: data from an animal model.

Post thyroidectomy hemorrhage is a potentially life-threatening complication. As the mechanism leading to hypoxemic brain damage and death is still unknown, our aim was to examine the underlaying pathophysiology in an animal model. A series of experiments was performed in our established model for post thyroidectomy hemorrhage in 6 pigs. First, post thyroidectomy hemorrhage was simulated with an artificial increase of cervical compartment pressure. Second, spontaneous bleeding into the cervical compartment was initiated. Primary outcome measure is the correlation between cerebral oxygenation and cervical compartment pressure. With an increase in cervical compartment pressure apnea could be detected in all experiments. A significant 24.2% (9.5-34.4%) decrease of cerebral oxygenation at time of apnea (47.0%; 38.0-65.0%) compared to baseline values (63.5%; 56.0-74.0%; P=0.043) occurred due increase of cervical compartment pressure concurrent with an impaired cerebral perfusion. Apnea occurred about 200 sec after a 10% decrease of cerebral oxygenation, but 35 sec before a 10% decrease of peripheral oxygenation. Spontaneous bleeding into the cervical compartment causes an increase of cervical compartment pressure reaching levels of the mean arterial blood pressure 56.0 (35.0-72.0) mmHg. Peripheral hypoxemia occurs with relevant delay in time after decrease of cerebral perfusion and cerebral hypoxemia, therefore cerebral hypoxemia seems to be causal for a central apnea. With this evidence of impaired cerebral perfusion and cerebral hypoxemia due to an increased cervical compartment pressure we can disprove the historic theory of tracheal collapse due to a compressive hematoma in post thyroidectomy hemorrhage. A cervical compartment syndrome seems to be causal, not only for brain hypoxemia but also an additional laryngo-pharyngeal mucosal edema.

Acute Effect of a Simultaneous Exercise and Cognitive Task on Executive Functions and Prefrontal Cortex Oxygenation in Healthy Older Adults.

The rapid increase in population aging and associated age-related cognitive decline requires identifying innovative and effective methods to prevent it. To manage this socio-economic challenge, physical, cognitive, and combined stimulations are proposed. The superiority of simultaneous training compared to passive control and physical training alone seems to be an efficient method, but very few studies assess the acute effect on executive function. This study aimed to investigate the acute effect of simultaneous physical and cognitive exercise on executive functions in healthy older adults, in comparison with either training alone. Seventeen healthy older adults performed three experimental conditions in randomized order: physical exercise, cognitive exercise, and simultaneous physical and cognitive exercise. The protocol involved a 30 min exercise duration at 60% of theoretical maximal heart rate or 30 min of cognitive exercise or both. Executive functions measured by the Stroop task and pre-frontal cortex oxygenation were assessed before and after the intervention. We found a main effect of time on executive function and all experimental condition seems to improve inhibition and flexibility scores (<0.05). We also found a decrease in cerebral oxygenation (Δ[HbO2]) in both hemispheres after each intervention in all cognitive performance assessed (p < 0.05). Simultaneous physical and cognitive exercise is as effective a method as either physical or cognitive exercise alone for improving executive function. The results of this study may have important clinical repercussions by allowing to optimize the interventions designed to maintain the cognitive health of older adults since simultaneous provide a time-efficient strategy to improve cognitive performance in older adults.

Orthostatic Resiliency During Successive Hypoxic, Hypoxic Orthostatic Challenge: Successful vs. Unsuccessful Cardiovascular and Oxygenation Strategies.

Introduction: Rapid environmental changes, such as successive hypoxic-hypoxic orthostatic challenges (SHHOC) occur in the aerospace environment, and the ability to remain orthostatically resilient (OR) relies upon orchestration of physiological counter-responses. Counter-responses adjusting for hypoxia may conflict with orthostatic responses, and a misorchestration can lead to orthostatic intolerance (OI). The goal of this study was to pinpoint specific cardiovascular and oxygenation factors associated with OR during a simulated SHHOC.Methods: Thirty one men underwent a simulated SHHOC consisting of baseline (P0), normobaric hypoxia (Fi02 = 12%, P1), and max 60 s of hypoxic lower body negative pressure (LBNP, P2). Alongside anthropometric variables, non-invasive cardiovascular, central and peripheral tissue oxygenation parameters, were recorded. OI was defined as hemodynamic collapse during SHHOC. Comparison of anthropometric, cardiovascular, and oxygenation parameters between OR and OI was performed via Student’s t-test. Within groups, a repeated measures ANOVA test with Holm-Sidak post hoc test was performed. Performance diagnostics were performed to assess factors associated with OR/OI (sensitivity, specificity, positive predictive value PPV, and odd’s ratio OR).Results: Only 9/31 were OR, and 22/31 were OI. OR had significantly greater body mass index (BMI), weight, peripheral Sp02, longer R-R Interval (RRI) and lower heart rate (HR) at P0. During P1 OR exhibited significantly higher cardiac index (CI), stroke volume index (SVI), and lower systemic vascular resistance index (SVRI) than OI. Both groups exhibited a significant decrease in cerebral oxygenation (TOIc) with an increase in cerebral deoxygenated hemoglobin (dHbc), while the OI group showed a significant decrease in cerebral oxygenated hemoglobin (02Hbc) and peripheral oxygenation (TOIp) with an increase in peripheral deoxygenated hemoglobin (dHbp). During P2, OR maintained significantly greater CI, systolic, mean, and diastolic pressure (SAP, MAP, DAP), with a shortened RRI compared to the OI group, while central and peripheral oxygenation were not different. Body weight and BMI both showed high sensitivity (0.95), low specificity (0.33), a PPV of 0.78, with an OR of 0.92, and 0.61. P0 RRI showed a sensitivity of 0.95, specificity of 0.22, PPV 0.75, and OR of 0.99. Delta SVI had the highest performance diagnostics during P1 (sensitivity 0.91, specificity 0.44, PPV 0.79, and OR 0.8). Delta SAP had the highest overall performance diagnostics for P2 (sensitivity 0.95, specificity 0.67, PPV 0.87, and OR 0.9).Discussion: Maintaining OR during SHHOC is reliant upon greater BMI, body weight, longer RRI, and lower HR at baseline, while increasing CI and SVI, minimizing peripheral 02 utilization and decreasing SVRI during hypoxia. During hypoxic LBNP, the ability to remain OR is dependent upon maintaining SAP, via CI increases rather than SVRI. Cerebral oxygenation parameters, beyond 02Hbc during P1 did not differ between groups, suggesting that the during acute hypoxia, an increase in cerebral 02 consumption, coupled with increased peripheral 02 utilization does seem to play a role in OI risk during SHHOC. However, cardiovascular factors such as SVI are of more value in assessing OR/OI risk. The results can be used to implement effective aerospace crew physiological monitoring strategies.

Detecting mild cognitive impairment by quantifying oculometric features during variable cognitive workload: The novel rapid Oculo‐Cognitive Addition Test

AbstractBackgroundThe need exists for a device that can rapidly and accurately assess mild cognitive impairment (MCI). Because the link between oculometrics and cognition is well‐documented, the Oculo‐Cognitive Addition Test (OCAT) was developed which tracks users’ eye movements as they complete a simple mental addition test.MethodOCAT consisted of 12 trials of summing three consecutive single‐digit numbers, shown separately on three consecutive screens (Figure 1). The first, second, and third screen in each trial corresponded to low, medium, and high cognitive workload. Using an infinity‐loop pattern of 24 symmetrical positions, eye movements were captured systematically in horizontal, vertical, and diagonal directions (Figure 2).MCI was simulated by exposing subjects to 5 minutes of hypoxic gas mixture (8% O2 + balance N2). 20 subjects completed OCAT in baseline (i.e. normal room air), hypoxic, and post‐baseline (i.e. 20 minutes of room air) conditions. Raw scan‐paths were collected with an eye‐tracking device. Oculometrics pertaining to fixations and saccades were extracted. Statistical significance was assessed using repeated measures ANOVA. Effect size and clinical significance was evaluated using computed Cohen’s d.ResultOCAT completion time significantly increased from baseline to hypoxia, which corresponded to a significant decrease in cerebral oxygenation from baseline to hypoxia (Figure 3). From baseline to hypoxia, saccadic latency significantly increased while saccadic velocity significantly decreased in the diagonal direction, however, results in the horizontal and vertical directions were not significant (Figure 4). Fixation time significantly increased from baseline to hypoxia in medium and high cognitive workload, but did not significantly change in low cognitive workload (Figure 5). From baseline to hypoxia, fixation size did not significantly change in any cognitive workload, however, the fluctuation in fixation size significantly increased in medium cognitive workload. From baseline to hypoxia, fixation area significantly increased in low and high cognitive workload, but did not significantly change in medium cognitive workload.ConclusionOCAT can detect subtle changes in oculometrics that correlate with MCI. This study provides rationale for providing varying degrees of cognitive load to elucidate subtle changes in oculometrics that may otherwise go undetected in neurocognitive tests that do not increase cognitive load.

Effects of hypothermia, hypoxia, and hypercapnia on brain oxygenation and hemodynamic parameters during simulated avalanche burial: a porcine study.

Avalanche patients who are completely buried but still able to breathe are exposed to hypothermia, hypoxia, and hypercapnia (triple H syndrome). Little is known about how these pathological changes affect brain physiology. The study aim was to investigate the effect of hypothermia, hypoxia, and hypercapnia on brain oxygenation and systemic and cerebral hemodynamics. Anesthetized pigs were surface cooled to 28°C. Fraction of inspiratory oxygen ([Formula: see text]) was reduced to 17% and hypercapnia induced. Hemodynamic parameters and blood gas values were monitored. Cerebral measurements included cerebral perfusion pressure (CPP), brain tissue oxygen tension ([Formula: see text]), cerebral venous oxygen saturation ([Formula: see text]), and regional cerebral oxygen saturation (rSo2). Tests were interrupted when hemodynamic instability occurred or 60 min after hypercapnia induction. ANOVA for repeated measures was used to compare values across phases. There was no clinically relevant reduction in cerebral oxygenation ([Formula: see text], [Formula: see text], rSo2) during hypothermia and initial [Formula: see text] reduction. Hypercapnia was associated with an increase in pulmonary resistance followed by a decrease in cardiac output and CPP, resulting in hemodynamic instability and cerebral desaturation (decrease in [Formula: see text], [Formula: see text], rSo2). Hypercapnia may be the main cause of cardiovascular instability, which seems to be the major trigger for a decrease in cerebral oxygenation in triple H syndrome despite severe hypothermia.NEW & NOTEWORTHY Avalanche patients who are completely buried but still able to breathe are exposed to hypothermia, hypoxia, and hypercapnia (triple H syndrome). In a porcine model, there was no clinically relevant reduction in cerebral oxygenation during hypothermia and initial reduction of fraction of inspiratory oxygen ([Formula: see text]), as observed during hypercapnia. Hypercapnia may be the main cause of cardiovascular instability, which seems to be the major trigger for a decrease in cerebral oxygenation in triple H syndrome despite severe hypothermia.

Application of near-infrared spectroscopy in extremely and very low birth weight infants for red blood cells transfusion

Near-infrared spectroscopy (NIRS), or cerebral oximetry, is a non-invasive method for assessing the oxidative status (saturation of hemoglobin with oxygen) mainly in the blood of cerebral venous vessels, which is increasingly used in clinical practice, in particular in neonatology. This method allows us to evaluate not only tissue perfusion, but also to determine the differences between the indicators of cerebral and peripheral oxygenation. Few studies have described improvements in tissue oxygenation indicators determined by NIRS after red blood cells transfusion in premature newborns. In our study we registered the oximetry indicators before and after red blood cells transfusion in extremely and very low birth weight infants (n = 55). This clinical study was approved by the Biomedical Research Ethics Committee (Protocol No. 19 dated 17 November 2016) and the Scientific Council of the Kulakov National Medical Research Center for Obstetrics, Gynecology and Perinatology of Ministry of Healthcare of the Russian Federation (Protocol No. 19 dated 29 November 2016). Our study demonstrated a statistically significant increase in CrSO2 , SrSO2 , RrSO2 and SCOR and a decrease in C-FTOE, S-FTOE after a blood transfusion. The study also showed that a decrease in NIRS values (SCOR ≤ 0.76, C-FTOE ≥ 0.29, CrSO2 ≤ 64%, SrSO2 ≤ 54%, and RrSO2 ≤ 56%) can serve as an additional non-invasive measure of anemia and its progression; it helps detect a decrease in cerebral oxygenation at an early, preclinical stage of disease, and can also be used as an additional indicator of the need for red blood cell transfusions.

Effect of hyperextension of the neck (rose position) on cerebral blood oxygenation in patients who underwent cleft palate reconstructive surgery: prospective cohort study using near-infrared spectroscopy

ObjectivesTo facilitate the best approach during cleft palate surgery, children are positioned with hyperextension of the neck. Extensive head extension may induce intraoperative cerebral ischemia if collateral flow is insufficient. To evaluate and monitor the effect of cerebral blood flow on cerebral tissue oxygenation, near-infrared spectroscopy has proved to be a valuable method. The aim of this study was to evaluate and quantify whether hyperextension affects the cerebral tissue oxygenation in children during cleft palate surgery.Materials and methodsThis prospective study included children (ASA 1 and 2) under the age of 3 years old who underwent cleft palate repair at the Wilhelmina Children’s Hospital, in The Netherlands. Data were collected for date of birth, cleft type, date of cleft repair, and physiological parameters (MAP, saturation, heart rate, expiratory CO2 and O2, temperature, and cerebral blood oxygenation) during surgery. The cerebral blood oxygenation was measured with NIRS.ResultsThirty-four children were included in this study. The majority of the population was male (61.8%, n = 21). The mixed model analyses showed a significant drop at time of Rose position of − 4.25 (69–74 95% CI; p < 0.001) and − 4.39 (69–74 95% CI; p < 0.001). Postoperatively, none of the children displayed any neurological disturbance.ConclusionThis study suggests that hyperextension of the head during cleft palate surgery leads to a significant decrease in cerebral oxygenation. Severe cerebral desaturation events during surgery were uncommon and do not seem to be of clinical relevance in ASA 1 and 2 children.Clinical relevanceThere was a significant drop in cerebral oxygenation after positioning however it is not clear whether this drop is truly significant physiologically in ASA 1 and 2 patients.

Effects of continuous positive airway pressure treatment on mood, cognition, and quality of life in patients with obstructive sleep apnea

Background Obstructive sleep apnea (OSA)-hypopnea syndrome is characterized by breathing cessation with temporary decrease in cerebral oxygenation that may lead to poor concentration up to cognitive impairment and mood problems. Continuous positive airway pressure (CPAP) is essential for treating OSA-hypopnea syndrome, but its role remains debatable. This current work was designed to evaluate the effect of CPAP therapy on neuropsychiatric complications of OSA including mood disorders (depression and anxiety), neurocognitive disorders, and sleep-related quality of life (QoL). Patients and methods A total of 113 newly diagnosed patients with OSA were followed up after receiving CPAP treatment for 3 months, by assessment of Epworth Sleepiness Scale, Functional Outcome of Sleep Questionnaire, Hospital Anxiety and Depression Scale (HADS), and neurocognitive assessment by Montreal Cognitive Assessment (MoCA) scale. Results After 3 months on CPAP, patients with OSA achieved improvement in sleep symptoms, Epworth Sleepiness Scale, Functional Outcome of Sleep Questionnaire-10 (P Conclusion A remarkable improvement was evident in sleep-related QoL, depression, anxiety, and some domains of cognitive function, after using CPAP treatment among complaint patients with OSA. Depression, anxiety, and cognitive dysfunction are the prevalent neuropsychiatric complications of OSA and have to be assessed in all patients with OSA. Minimal oxygen saturation was the most striking risk factor correlated with sleep-related QoL and all the studied parameters of neuropsychiatric disorders.

Decrease in Cerebral Oxygen Saturation During the 6-Minute Walk Test in Pediatric Pulmonary Arterial Hypertension.

This observational study aimed to investigate the relationship between regional cerebral oxygen saturation (rSO2) during the 6-minute walk test (6-MWT) and the demographic/clinical features of patients with pulmonary arterial hypertension (PAH). Cerebral oxygenation was evaluated during the 6-MWT in 20 pediatric patients with PAH aged ≥ 7years [13 male, 7 female; median age 12.25 (range 7-18) years]. In all patients, regional cerebral oxygen saturation (rSO2), arterial oxygen saturation (SpO2), and heart rate (HR) were measured using near-infrared spectroscopy (NIRS) for 2min before the test, during the 6-MWT test, and 2min after the test. The relationship between the changes in rSO2, heart rate, and SpO2 values and clinical and laboratory features was compared statistically. The mean pulmonary arterial pressure (mPAP) was 77 (range 25-126) mmHg, and the median 6-minute walk distance (6-MWD) was 427.5 (300-570) m. The changes in rSO2 measurements ranged between 3.41 and 21.8%, and 70% of the patients had a greater than 10% decrease in rSO2 during the test compared with baseline. Eight patients showed a decrease in rSO2 without SpO2 changes. The present study demonstrated a significant decrease in cerebral oxygenation in pediatric patients with PAH during the 6-MWT. We hypothesized that using a combination of the 6-MWT and regional cerebral oxygenation monitoring in pediatric patients with PAH in order to evaluate exercise capacity, as a reflection of reduced daily activities, would provide more precise predictive values than the 6-MWT alone.

Cerebral Oxygenation During Neonatal Intubation-Ancillary Study of the Prettineo-Study.

Purpose: This study aimed to describe cerebral Near InfraRed Spectroscopy (NIRS) profiles during neonatal intubation using two different premedication regimens.Methods: Neonates requiring non-emergency intubation were enrolled in an ancillary study, conducted in two French Neonatal Intensive Care Units participating in a larger on-going multicenter, double blind, randomized, controlled trial. Patients were randomly assigned to the “atropine-propofol” (Prop) group or the “atropine-atracurium-sufentanil” (SufTrac) group. Regional cerebral oxygen saturation (rScO2), pulse oxymetry (SpO2), mean arterial blood pressure (MABP), and transcutaneous partial pressure of carbon dioxide (TcPCO2) were collected at 9 predefined time points from 1 min before to 60 min after the first drug injection. The two primary outcomes were a decrease in rScO2 value >20% from baseline and a decrease in fractional cerebral tissue oxygen extraction (FTOE) value >10% from baseline, at any time point. Secondary outcomes included physiological parameters changes over time and correlations between mean arterial blood pressure, and FTOE at different time points. Descriptive results were obtained and exploratory statistical analyses were performed for 24 included patients.Results: rScO2 decreased in 5/11 (46%) infants from the Prop group and 10/13 (77%) from the SufTrac group (p = 0.11); FTOE decreased in 10/11 (91%) infants from the Prop group, and 12/13 (92%) from the SufTrac group (p = 0.90). rScO2 values decreased over time in both groups, whereas FTOE's pattern appeared more stable. SpO2 and transcutaneous TcPCO2 seemed more preserved in the Prop group while MABP seemed more preserved in the SufTrac group. No important correlation was observed between MABP and FTOE (r = 0.08 to 0.12 across the time points).Conclusion: Our results suggest a frequent decrease in cerebral oxygenation without obvious impairment in cerebral autoregulation during neonatal intubation with premedication. This study confirms the feasibility and the informative value of cerebral NIRS monitoring in this setting.Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02700893.

Cerebral oxygenation associated with INSURE versus LISA procedures in surfactant-deficient newborn piglet RDS model.

BackgroundNasal continuous‐positive airway pressure (nCPAP) with the INSURE (INtubation‐SURfactant‐Extubation) or LISA (Less‐Invasive Surfactant Administration) procedures are increasingly being chosen as the initial treatment for neonates with surfactant deficiency. Our objective was to compare the effects on cerebral oxygenation of different methods for surfactant administration: INSURE and LISA, using a nasogastric tube (NT) or a LISAcath® catheter, in spontaneously breathing SF‐deficient newborn piglets.MethodsEighteen newborn piglets with SF‐deficient lung injury produced by repetitive bronchoalveolar lavages were randomly assigned to INSURE, LISA‐NT, or LISAcath® groups. We assessed pulmonary (gas exchange, lung mechanics, lung histology) and hemodynamic (mean arterial blood pressure, heart rate) changes, cerebral oxygenation (cTOI) and cerebral fractional tissue extraction (cFTOE), with near‐infrared spectroscopy, carotid blood flow and brain histology.ResultsSF‐deficient piglets developed respiratory distress (FiO2 = 1, pH <7.2, PaCO2 >70 mmHg, PaO2 <70 mmHg, Cdyn <0.5 mL/cmH2O/kg). Rapid improvements in pulmonary status were observed in all surfactant‐treated groups without hemodynamic alterations. In the INSURE group, a transient decrease in cTOI occurred during and immediately after surfactant administration, while cTOI only decreased during surfactant administration in the LISA‐NT group and did not change significantly in the LISAcath® group. Brain injury scores were low in all surfactant‐treated groups.ConclusionIn spontaneously breathing SF‐deficient newborn piglets, short‐lasting decreases in cerebral oxygenation are associated with surfactant administration by the INSURE method or LISA using an NT, while no cerebral oxygenation changes occurred with LISA using a LISAcath®. Notably, none of treatments studied seems to have a negative impact on the neonatal brain.

Correction: Monitoring cerebral oxygenation of the immature brain: a neuroprotective strategy?

The original version of this article contained an error in the legend of Fig.3, which incorrectly read:Figure3. a The patterns of arterial saturation (SaO2; orange), and rScO2 (blue) and mean arterial blood pressure (MABP; red) of an extremely preterm infant on postnatal day 1. The initial rScO2 values were very low (red box). These low values seemed to be associated with PaCO2 values below 30 mmHg (brown squares; starting at 24 mmHg. SaO2 and MABPs values were always normal. When PaCO2 values increased above values of 30 mmHg (brown arrow) the rScO2 increased and eventually normalized. b The patterns of rScO2 (blue) and mean arterial blood pressure (MABP; red) of a very preterm girl, starting on postnatal day 1, was especially marked by a steep decrease in cerebral oxygenation (rScO2;red box) to very low values (<40%). Echocardiographic investigation early on postnatal day 2 revealed a hemodynamically significant ductus arteriosus. Subsequent ductal closure with indomethacin (2 courses) was followed by normalization of cerebral oxygenation. c The patterns of heart rate (HR), arterial saturation (SaO2) and rScO2 (red box) in a preterm neonate.with severe anemia. The rather low rScO2 recovered following packed red blood cell transfusion (courtesy Prof. Gunnar Naulaers, UZ Leuven).This has been corrected in both the PDF and HTML versions of the article.

P4428Near-infrared spectroscopy demonstrated a heart rate-dependent decrease in cerebral oxygenation during paroxysmal supraventricular tachycardia as well as ventricular tachycardia

P4428Near-infrared spectroscopy demonstrated a heart rate-dependent decrease in cerebral oxygenation during paroxysmal supraventricular tachycardia as well as ventricular tachycardia

Changes in Cerebral Oxygenation in Preterm Infants With Progressive Posthemorrhagic Ventricular Dilatation

BackgroundOptimal timing of intervention in neonatal progressive posthemorrhagic hydrocephalus is often a difficult decision. Unchecked hydrocephalus can lead to irreversible brain injury through impaired perfusion, while placement of a shunt is not without long-term morbidity. The purpose of this study was to assess the use of near-infrared spectroscopy to measure changes in regional cerebral oxygen saturation as an indicator of cerebral perfusion in infants with progressive posthemorrhagic ventricular dilatation. MethodsNear-infrared spectroscopy was used to measure regional cerebral oxygen saturation for more than a one-hour period in infants within 24 hours of cranial ultrasound. Simultaneous pulse oximetry was recorded and oxygen extraction was calculated. Ventricular size was measured by ultrasound using the frontal-occipital horn ratio and compared with average oxygen saturation and oxygen extraction. Statistical analysis was done using the Spearman rank test and analysis of variance. ResultsVentricular measurements were made in 20 very low birth weight premature infants with periventricular-intraventricular hemorrhage and 12 infants with normal ultrasound scans. Ventricular dilatation was associated with lower cerebral oxygen saturation and higher oxygen extraction (P < 0.001). Progressive ventricular dilatation was inversely related to changes in cerebral oxygen saturation (P < 0.001). ConclusionsProgressive posthemorrhagic ventricular dilatation is associated with a significant decrease in cerebral oxygenation and increase in oxygen extraction suggesting a decrease in cerebral perfusion. Near-infrared spectroscopy could potentially provide additional clinical information to assist in determining optimal timing of surgical intervention in preterm infants with progressive ventricular enlargement.

The effect of dexmedetomidine on cerebral perfusion and oxygenation in healthy piglets with normal and lowered blood pressure anaesthetized with propofol-remifentanil total intravenous anaesthesia

BackgroundDuring anaesthesia and surgery, in particular neurosurgery, preservation of cerebral perfusion and oxygenation (CPO) is essential for normal postoperative brain function. The isolated effects on CPO of either individual anaesthetic drugs or entire anaesthetic protocols are of importance in both clinical and research settings. Total intravenous anaesthesia (TIVA) with propofol and remifentanil is widely used in human neuroanaesthesia. In addition, dexmedetomidine is receiving increasing attention as an anaesthetic adjuvant in neurosurgical, intensive care, and paediatric patients. Despite the extensive use of pigs as animal models in neuroscience and the increasing use of both propofol-remifentanil and dexmedetomidine, very little is known about their combined effect on CPO in pigs with uninjured brains. This study investigates the effect of dexmedetomidine on CPO in piglets with normal and lowered blood pressure during background anaesthesia with propofol-remifentanil TIVA. Sixteen healthy female Danish pigs (crossbreeds of Danish Landrace, Yorkshire and Duroc, 25–34 kg) were used. Three animals were subsequently excluded. The animals were randomly allocated into one of two groups with either normal blood pressure (NBP, n = 6) or with induced low blood pressure (LBP, n = 7). Both groups were subjected to the same experimental protocol. Intravenous propofol induction was performed without premedication. Anaesthesia was maintained with propofol-remifentanil TIVA, and later supplemented with continuous infusion of dexmedetomidine. Assessments of cerebral perfusion obtained by laser speckle contrast imaging (LSCI) were related to cerebral oxygenation measures (PbrO2) obtained by an intracerebral Clark-type Licox probe.ResultsAddition of dexmedetomidine resulted in a 32% reduction in median PbrO2 values for the LBP group (P = 0.03), but no significant changes in PbrO2 were observed for the NBP group. No significant changes in LSCI readings were observed in either group between any time points, despite a 28% decrease in the LBP group following dexmedetomidine administration. Caval block resulted in a significant (P = 0.02) reduction in median MAP from 68 mmHg (range 63–85) at PCB to 58 mmHg (range 53–63) in the LBP group, but no significant differences in either PbrO2 or LSCI were observed due to this intervention (P = 0.6 and P = 0.3 respectively).ConclusionsAddition of dexmedetomidine to propofol-remifentanil TIVA resulted in a significant decrease in cerebral oxygenation (PbrO2) measurements in piglets with lowered blood pressure. Cerebral perfusion (LSCI) did not decrease significantly in this group. In piglets with normal blood pressure, no significant changes in cerebral perfusion or oxygenation were seen in response to addition of dexmedetomidine to the background anaesthesia.

Bedside Monitoring of Cerebral Energy State During Cardiac Surgery—A Novel Approach Utilizing Intravenous Microdialysis

This study investigated whether the lactate-to-pyruvate (LP) ratio obtained by microdialysis (MD) of the cerebral venous outflow reflected a derangement of global cerebral energy state during cardiopulmonary bypass (CPB). Interventional, prospective, randomized study. Single-center, university teaching hospital. The study included 10 patients undergoing primary, elective coronary artery bypass grafting. Patients were randomized blindly to low mean arterial pressure (MAP) (40-60 mmHg; n = 5) or high MAP (60-80 mmHg; n = 5) during CPB. The MD catheters were positioned in a retrograde direction into the jugular bulb, and a reference catheter was inserted into the brachial artery. The correlations among LP ratio, MAP, data obtained from bifrontal near-infrared spectroscopy (NIRS), and postoperative neurologic outcome measures were assessed. The correlated difference between pooled LP ratio (low and high MAP) of the jugular venous and the arterial blood was significant (LParterial 17 [15-20] v LPvenous 26 [23-27]; p = 0.0001). No cerebral desaturations (decrease in rSO2>20% from baseline) were observed in either group during CPB. In each group, 50% of the patients showed significant cognitive decline (mini-mental state examination, 3 points) 2 days after surgery. The LP ratio of cerebral venous blood increased significantly during CPB, indicating compromised cerebral oxidative metabolism. Conventional monitoring of rSO2 by NIRS did not show a corresponding decrease in cerebral oxygenation. As the patients exhibited decreased cognitive functions after CPB, increases in jugular venous LP ratio may be a sensitive indicator of impending cerebral damage.

Cerebral oxygenation during changes in vascular resistance and flow in patients on cardiopulmonary bypass - a physiological proof of concept study.

Despite a rise in blood pressure, cerebral oxygenation decreases following phenylephrine administration, and we hypothesised that phenylephrine reduces cerebral oxygenation by activating cerebral α1 receptors. We studied patients on cardiopulmonary bypass during constant flow. Phenylephrine raised mean arterial pressure (α1 -mediated) from mean (SD) 69 (8) mmHg to 79 (8) mmHg; p = 0.001, and vasopressin raised mean arterial pressure (V1 mediated) from 69 (8) mmHg to 83 (6) mmHg; p = 0.001. Both drugs elicited a comparable decrease in cerebral oxygenation from 61 (7)% to 60 (7)%; p = 0.023 and 61 (8)% to 59 (8)%; p = 0.022, respectively. This implies that after phenylephrine or vasopressin administration, cerebral oxygenation declines as a result of cerebral vasoconstriction, due to either both cerebral α1 and V1 receptors being equipotentially activated or to an intrinsic myogenic mechanism of cerebral vasculature in reaction to blood pressure elevation.