We did not reproduce the results of previous studies that reported a lower incidence of anesthesia awareness with BIS monitoring, and the use of the BIS protocol was not associated with reduced administration of volatile anesthetic gases. Anesthesia awareness occurred even when BIS values and ETAG concentrations were within the target ranges. Our findings do not support routine BIS monitoring as part of standard practice. (ClinicalTrials.gov number, NCT00281489 [ClinicalTrials.gov].).

Background Brief isoflurane anesthesia induces neuroapoptosis in the developing rodent brain, but susceptibility of nonhuman primates to the apoptogenic action of isoflurane has not been studied. Therefore, we exposed postnatal day 6 (P6) rhesus macaques to a surgical plane of isoflurane anesthesia for 5 h, and studied the brains 3 h later for histopathological changes. Method With the same intensity of physiological monitoring typical for human neonatal anesthesia, five P6 rhesus macaques were exposed for 5 h to isoflurane maintained between 0.7 and 1.5 end tidal Vol% (endotracheally intubated, mechanically ventilated), and five controls were exposed for 5 h to room air without further intervention. Three hours later, the brains were harvested and serially sectioned across the entire forebrain and midbrain, and stained immunohistochemically with antibodies to activated caspase-3 for detection and quantification of apoptotic neurons. Results Quantitative evaluation of brain sections revealed a median of 32.5 (range, 18.0 to 48.2) apoptotic cells per mm3 of brain tissue in the isoflurane group and only 2.5 (range, 1.9 to 3.8) in the control group (difference significant at p = 0.008). Apoptotic neuronal profiles were largely confined to the cerebral cortex. In the control brains, they were sparse and randomly distributed, whereas in the isoflurane brains they were abundant and preferentially concentrated in specific cortical layers and regions. Conclusion The developing nonhuman primate brain is sensitive to the apoptogenic action of isoflurane, and displays a 13-fold increase in neuroapoptosis after 5 h exposure to a surgical plane of isoflurane anesthesia.

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IMPORTANCE Intraoperative electroencephalogram (EEG) waveform suppression, often suggesting excessive general anesthesia, has been associated with postoperative delirium. OBJECTIVE To assess whether EEG-guided anesthetic administration decreases the incidence of postoperative delirium. DESIGN, SETTING, AND PARTICIPANTS Randomized clinical trial of 1232 adults aged 60 years and older undergoing major surgery and receiving general anesthesia at Barnes-Jewish Hospital in St INTERVENTIONS Patients were randomized 1:1 (stratified by cardiac vs noncardiac surgery and positive vs negative recent fall history) to receive EEG-guided anesthetic administration (n = 614) or usual anesthetic care (n = 618). MAIN OUTCOMES AND MEASURES The primary outcome was incident delirium during postoperative days 1 through 5. Intraoperative measures included anesthetic concentration, EEG suppression, and hypotension. Adverse events included undesirable intraoperative movement, intraoperative awareness with recall, postoperative nausea and vomiting, medical complications, and death. RESULTSOf the 1232 randomized patients (median age, 69 years [range, 60 to 95]; 563 women [45.7%]), 1213 (98.5%) were assessed for the primary outcome. Delirium during postoperative days 1 to 5 occurred in 157 of 604 patients (26.0%) in the guided group and 140 of 609 patients (23.0%) in the usual care group (difference, 3.0% [95% CI, −2.0% to 8.0%]; P = .22). Median end-tidal volatile anesthetic concentration was significantly lower in the guided group than the usual care group (0.69 vs 0.80 minimum alveolar concentration; difference, −0.11 [95% CI, −0.13 to −0.10), and median cumulative time with EEG suppression was significantly less (7 vs 13 minutes; difference, −6.0 [95% CI, −9.9 to −2.1]). There was no significant difference between groups in the median cumulative time with mean arterial pressure below 60 mm Hg (7 vs 7 minutes; difference, 0.0 [95% CI, −1.7 to 1.7]). Undesirable movement occurred in 137 patients (22.3%) in the guided and 95 (15.4%) in the usual care group. No patients reported intraoperative awareness. Postoperative nausea and vomiting was reported in 48 patients (7.8%) in the guided and 55 patients (8.9%) in the usual care group. Serious adverse events were reported in 124 patients (20.2%) in the guided and 130 (21.0%) in the usual care group. Within 30 days of surgery, 4 patients (0.65%) in the guided group and 19 (3.07%) in the usual care group died.CONCLUSIONS AND RELEVANCE Among older adults undergoing major surgery, EEG-guided anesthetic administration, compared with usual care, did not decrease the incidence of postoperative delirium. This finding does not support the use of EEG-guided anesthetic administration for this indication. 40. Muhlhofer WG, Zak R, Kamal T, et al. Burst-suppression ratio underestimates absolute duration of electroencephalogram suppression compared with visual analysis of intraoperative electroencephalogram.

To identify genetic determinants of hypoxic cell death, we screened for hypoxia-resistant (Hyp) mutants in Caenorhabditis elegans and found that specific reduction-of-function (rf) mutants of daf-2, an insulin/insulinlike growth factor (IGF) receptor (INR) homolog gene, were profoundly Hyp. The hypoxia resistance was acutely inducible just before hypoxic exposure and was mediated through an AKT-1/PDK-1/forkhead transcription factor pathway overlapping with but distinct from signaling pathways regulating life-span and stress resistance. Selective neuronal and muscle expression of daf-2(+) restored hypoxic death, and daf-2(rf) prevented hypoxia-induced muscle and neuronal cell death, which demonstrates a potential for INR modulation in prophylaxis against hypoxic injury of neurons and myocytes.