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Changes in cerebral oxygenation based on intraoperative ventilation strategy.

ABSTRACT: Introduction:Cerebral oxygenation can be monitored clinically by cerebral oximetry (regional oxygen saturation, rSO2) using near-infrared spectroscopy (NIRS). Changes in rSO2 have been shown to precede changes in pulse oximetry, providing an early detection of clinical deterioration. Cerebral oximetry values may be affected by various factors, including changes in ventilation. The aim of this study was to evaluate the changes in rSO2 during intraoperative changes in mechanical ventilation. Patients and methods:Following the approval of the institutional review board (IRB), tissue and cerebral oxygenation were monitored intraoperatively using NIRS. Prior to anesthetic induction, the NIRS monitor was placed on the forehead and over the deltoid muscle to obtain baseline values. NIRS measurements were recorded each minute over a 5-min period during general anesthesia at four phases of ventilation: 1) normocarbia (35-40 mmHg) with a low fraction of inspired oxygen (FiO2) of 0.3; 2) hypocarbia (25-30 mmHg) and low FiO2 of 0.3; 3) hypocarbia and a high FiO2 of 0.6; and 4) normocarbia and a high FiO2. NIRS measurements during each phase were compared with sequential phases using paired t-tests. Results:The study cohort included 30 adolescents. Baseline cerebral and tissue oxygenation were 81% ± 9% and 87% ± 5%, respectively. During phase 1, cerebral rSO2 was 83% ± 8%, which decreased to 79% ± 8% in phase 2 (hypocarbia and low FiO2). Cerebral oxygenation partially recovered during phase 3 (81% ± 9%) with the increase in FiO2 and then returned to baseline during phase 4 (83% ± 8%). Each sequential change (e.g., phase 1 to phase 2) in cerebral oxygenation was statistically significant (p < 0.01). Tissue oxygenation remained at 87%-88% throughout the study. Conclusion:Cerebral oxygenation declined slightly during general anesthesia with the transition from normocarbia to hypocarbic conditions. The rSO2 decrease related to hypocarbia was easily reversed with a return to baseline values by the administration of supplemental oxygen (60% vs. 30%).

SUBMITTER: Dewhirst E

PROVIDER: S-EPMC6065577 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Changes in cerebral oxygenation based on intraoperative ventilation strategy.

Dewhirst Elisabeth E Walia Hina H Samora Walter P WP Beebe Allan C AC Klamar Jan E JE Tobias Joseph D JD

Medical devices (Auckland, N.Z.) 20180725

<h4>Introduction</h4>Cerebral oxygenation can be monitored clinically by cerebral oximetry (regional oxygen saturation, rSO<sub>2</sub>) using near-infrared spectroscopy (NIRS). Changes in rSO<sub>2</sub> have been shown to precede changes in pulse oximetry, providing an early detection of clinical deterioration. Cerebral oximetry values may be affected by various factors, including changes in ventilation. The aim of this study was to evaluate the changes in rSO<sub>2</sub> during intraoperative ...[more]

PMID: 30100768

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Project description:BackgroundGeneral anesthesia with neuromuscular blockade may facilitate total shoulder arthroplasty but appears to increase risk of cerebral oxygen desaturation. Cerebral desaturation is undesirable and is a proxy for risk of stroke.Purposes/questionsThis study tested the hypothesis that cerebral oxygen desaturation occurs frequently during general anesthesia with neuromuscular blockade and positive-pressure ventilation but does not occur with spontaneous ventilation. Correlations were sought among cerebral oxygen saturation, blood pressure, and cardiac index.MethodsWe designed a prospective, observational, cohort study to measure cerebral oxygenation in 25 patients during general anesthesia, both with and without positive-pressure ventilation. Patients undergoing elective shoulder arthroplasty in the sitting position received an arterial catheter, near-infrared spectroscopic measurement of cerebral oxygenation, and non-invasive cardiac output measurement. Moderate hypotension was allowed. Blood pressure was supported as needed with ephedrine or low-dose epinephrine (but avoiding phenylephrine). Hypercapnia (45 to 55 mmHg) was targeted during positive-pressure ventilation.ResultsNo cerebral oxygen desaturations occurred, regardless of ventilation mode. Under positive-pressure ventilation, the median (interquartile range: Q1, Q3) cerebral oxygenation was 110% of baseline (104, 113), the mean arterial pressure was 62% of baseline (59, 69), and the cardiac index was 82% of baseline (71, 104). Cerebral oxygenation did not correlate with blood pressure or cardiac index but had moderate correlation with end-tidal carbon dioxide. No strokes occurred.ConclusionsThere were no signs of inadequate brain perfusion during general anesthesia using paralytic agents. Positive-pressure ventilation with moderate hypotension in the sitting position does not endanger patients, in the context of moderate hypercapnia and hemodynamic support using ephedrine or epinephrine.

Project description:ObjectiveTo evaluate the effects of intraoperative protective ventilation on major postoperative respiratory complications and to define safe intraoperative mechanical ventilator settings that do not translate into an increased risk of postoperative respiratory complications.DesignHospital based registry study.SettingAcademic tertiary care hospital and two affiliated community hospitals in Massachusetts, United States.Participants69,265 consecutively enrolled patients over the age of 18 who underwent a non-cardiac surgical procedure between January 2007 and August 2014 and required general anesthesia with endotracheal intubation.InterventionsProtective ventilation, defined as a median positive end expiratory pressure (PEEP) of 5 cmH2O or more, a median tidal volume of less than 10 mL/kg of predicted body weight, and a median plateau pressure of less than 30 cmH2O.Main outcome measureComposite outcome of major respiratory complications, including pulmonary edema, respiratory failure, pneumonia, and re-intubation.ResultsOf the 69,265 enrolled patients 34,800 (50.2%) received protective ventilation and 34,465 (49.8%) received non-protective ventilation intraoperatively. Protective ventilation was associated with a decreased risk of postoperative respiratory complications in multivariable regression (adjusted odds ratio 0.90, 95% confidence interval 0.82 to 0.98, P=0.013). The results were similar in the propensity score matched cohort (odds ratio 0.89, 95% confidence interval 0.83 to 0.97, P=0.004). A PEEP of 5 cmH2O and median plateau pressures of 16 cmH2O or less were associated with the lowest risk of postoperative respiratory complications.ConclusionsIntraoperative protective ventilation was associated with a decreased risk of postoperative respiratory complications. A PEEP of 5 cmH2O and a plateau pressure of 16 cmH2O or less were identified as protective mechanical ventilator settings. These findings suggest that protective thresholds differ for intraoperative ventilation in patients with normal lungs compared with those used for patients with acute lung injury.

Project description:BACKGROUND:Postoperative neurocognitive dysfunction induced by anesthetics, particularly in elderly patients with impaired oxygenation, is a common complication of surgery and is eliciting increased interest in clinical practice. To investigate the effects of anesthetics on neurocognition, we compared the effects of propofol versus sevoflurane on cerebral oxygenation and cognitive outcome in patients with impaired cerebral oxygenation undergoing general anesthesia. METHODS:Sixty-three patients with impaired cerebral oxygenation (jugular venous bulb oxygen saturation [SjvO2] <50%) or cerebral blood flow/cerebral metabolic rate of oxygen ([CBF/CMRO2] ?15%) undergoing elective abdominal surgery were randomly allocated into propofol group (group P) or sevoflurane group (group S). The clinical parameters and jugular venous bulb blood gas analysis were monitored throughout the surgical procedure. Cognitive function was assessed with the mini-mental state examination and Montreal Cognitive Assessment at day 1 and day 7 following surgery. S100? protein in plasma was measured using enzyme-linked immunosorbent assay. RESULTS:The SjvO2 increased during anesthesia induction and surgery when compared to baseline but had no significant difference between group P and group S. When compared to baseline, the CBF/CMRO2 was increased only at the end of surgery and extubation in group P; however, the CBF/CMRO2 in group S was increased during anesthesia induction at 1 hour, 2 hours, end of surgery, and extubation. Furthermore, the CBF/CMRO2 in group S was significantly higher than that in group P during anesthesia induction at 1 hour, 2 hours, and end of surgery. S100? protein did not significantly change at extubation and 1 day after surgery in both groups when compared to baseline. There was no significant difference in mini-mental state examination and Montreal Cognitive Assessment scores between group P and group S at all time points. CONCLUSION:Sevoflurane showed similar effects in postoperative neurocognitive function as propofol but could improve cerebral oxygenation in patients with impaired cerebral oxygenation.

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Changes in cerebral oxygenation based on intraoperative ventilation strategy.

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Changes in cerebral oxygenation based on intraoperative ventilation strategy.

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