Background Protective ventilation may improve outcomes after major surgery. However, in the context of one-lung ventilation, such a strategy is incompletely defined. The authors hypothesized that a putative one-lung protective ventilation regimen would be independently associated with decreased odds of pulmonary complications after thoracic surgery. Methods The authors merged Society of Thoracic Surgeons Database and Multicenter Perioperative Outcomes Group intraoperative data for lung resection procedures using one-lung ventilation across five institutions from 2012 to 2016. They defined one-lung protective ventilation as the combination of both median tidal volume 5 ml/kg or lower predicted body weight and positive end-expiratory pressure 5 cm H2O or greater. The primary outcome was a composite of 30-day major postoperative pulmonary complications. Results A total of 3,232 cases were available for analysis. Tidal volumes decreased modestly during the study period (6.7 to 6.0 ml/kg; P < 0.001), and positive end-expiratory pressure increased from 4 to 5 cm H2O (P < 0.001). Despite increasing adoption of a “protective ventilation” strategy (5.7% in 2012 vs. 17.9% in 2016), the prevalence of pulmonary complications did not change significantly (11.4 to 15.7%; P = 0.147). In a propensity score matched cohort (381 matched pairs), protective ventilation (mean tidal volume 6.4 vs. 4.4 ml/kg) was not associated with a reduction in pulmonary complications (adjusted odds ratio, 0.86; 95% CI, 0.56 to 1.32). In an unmatched cohort, the authors were unable to define a specific alternative combination of positive end-expiratory pressure and tidal volume that was associated with decreased risk of pulmonary complications. Conclusions In this multicenter retrospective observational analysis of patients undergoing one-lung ventilation during thoracic surgery, the authors did not detect an independent association between a low tidal volume lung-protective ventilation regimen and a composite of postoperative pulmonary complications. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

BACKGROUND: The critical question of racial and gender diversity in pediatric anesthesia training programs has not been previously explored. The primary objective of this study was to evaluate trends by race/ethnicity and gender in pediatric anesthesiology fellowship training programs in the United States for the years 2000 to 2018. METHODS: Demographic data on pediatric anesthesiology fellows and anesthesiology residents were obtained from the self-reported data collected for the Journal of the American Medical Association’s annual report on Graduate Medical Education for the years 2000 to 2018. Diversity was assessed by calculating the proportions of trainees per year by gender and racial/ethnic groups in pediatric anesthesiology fellowship and anesthesiology residency programs. Logistic regression equations were developed to estimate the annual growth rate of each racial/ethnic groups. RESULTS: The number of pediatric anesthesiology fellows increased from 57 trainees in 2000–2001 to 202 in 2017–2018 at an average rate of 9 fellows per year (95% confidence interval [CI], 8–10). These increases were primarily due to white trainees (54.4%–63.4%) as the proportions of black (7.0%–4.5%), Asian (26.3%–21.3%), and other minority (12.3%–10.9%) trainees have remained low. The number of anesthesiology residents increased from 3950 trainees in 2000–2001 to 5940 in 2017–2018 at an average rate of 99 residents per year (95% CI, 88–111). Within all anesthesiology trainees, these increases were due to white trainees (55.7%–61.3%) as the proportion of black (5.0%–6.0%), Asian (25.8%–24.1%), and other minority trainees (8.2%–8.5%) has remained fairly constant over the time period. Despite the overall lower proportion of female anesthesiology residents (range: 27.0%–37.5%), a steady increase in the number of women in pediatric anesthesiology fellowship programs has reversed the gender imbalance in this population as of 2010. CONCLUSIONS: While historic gains have been made in gender diversity in pediatric anesthesiology, there is persistent underrepresentation of black and Hispanic trainees in pediatric anesthesiology. It appears that their low numbers in anesthesiology residency programs (the reservoir) may be partly responsible. Efforts to increase ethnic/racial diversity in pediatric anesthesiology fellowship and anesthesiology residency training programs are urgently needed.

BACKGROUND: Surgical patients are vulnerable to opioid dependency and related risks. Clinical-translational data suggest that caffeine may enhance postoperative analgesia. This trial tested the hypothesis that intraoperative caffeine would reduce postoperative opioid consumption. The secondary objective was to assess whether caffeine improves neuropsychological recovery postoperatively. METHODS: This was a single-center, randomized, placebo-controlled trial. Participants, clinicians, research teams, and data analysts were all blinded to the intervention. Adult (≥18 years old) surgical patients (n = 65) presenting for laparoscopic colorectal and gastrointestinal surgery were randomized to an intravenous caffeine citrate infusion (200 mg) or dextrose 5% in water (40 mL) during surgical closure. The primary outcome was cumulative opioid consumption through postoperative day 3. Secondary outcomes included subjective pain reporting, observer-reported pain, delirium, Trail Making Test performance, depression and anxiety screens, and affect scores. Adverse events were reported, and hemodynamic profiles were also compared between the groups. RESULTS: Sixty patients were included in the final analysis, with 30 randomized to each group. The median (interquartile range) cumulative opioid consumption (oral morphine equivalents, milligrams) was 77 mg (33–182 mg) for caffeine and 51 mg (15–117 mg) for placebo (estimated difference, 55 mg; 95% confidence interval [CI], −9 to 118; P = .092). After post hoc adjustment for baseline imbalances, caffeine was associated with increased opioid consumption (87 mg; 95% CI, 26–148; P = .005). There were otherwise no differences in prespecified pain or neuropsychological outcomes between the groups. No major adverse events were reported in relation to caffeine, and no major hemodynamic perturbations were observed with caffeine administration. CONCLUSIONS: Caffeine appears unlikely to reduce early postoperative opioid consumption. Caffeine otherwise appears well tolerated during anesthetic emergence.

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Background Neurophysiologic complexity in the cortex has been shown to reflect changes in the level of consciousness in adults but remains incompletely understood in the developing brain. This study aimed to address changes in cortical complexity related to age and anesthetic state transitions. This study tested the hypotheses that cortical complexity would (1) increase with developmental age and (2) decrease during general anesthesia. Methods This was a single-center, prospective, cross-sectional study of healthy (American Society of Anesthesiologists physical status I or II) children (n = 50) of age 8 to 16 undergoing surgery with general anesthesia at Michigan Medicine. This age range was chosen because it reflects a period of substantial brain network maturation. Whole scalp (16-channel), wireless electroencephalographic data were collected from the preoperative period through the recovery of consciousness. Cortical complexity was measured using the Lempel–Ziv algorithm and analyzed during the baseline, premedication, maintenance of general anesthesia, and clinical recovery periods. The effect of spectral power on Lempel–Ziv complexity was analyzed by comparing the original complexity value with those of surrogate time series generated through phase randomization that preserves power spectrum. Results Baseline spatiotemporal Lempel–Ziv complexity increased with age (yr; slope [95% CI], 0.010 [0.004, 0.016]; P < 0.001); when normalized to account for spectral power, there was no significant age effect on cortical complexity (0.001 [–0.004, 0.005]; P = 0.737). General anesthesia was associated with a significant decrease in spatiotemporal complexity (median [25th, 75th]; baseline, 0.660 [0.620, 0.690] vs. maintenance, 0.459 [0.402, 0.527]; P < 0.001), and spatiotemporal complexity exceeded baseline levels during postoperative recovery (0.704 [0.642, 0.745]; P = 0.009). When normalized, there was a similar reduction in complexity during general anesthesia (baseline, 0.913 [0.887, 0.923] vs. maintenance 0.851 [0.823, 0.877]; P < 0.001), but complexity remained significantly reduced during recovery (0.873 [0.840, 0.902], P < 0.001). Conclusions Cortical complexity increased with developmental age and decreased during general anesthesia. This association remained significant when controlling for spectral changes during anesthetic-induced perturbations in consciousness but not with developmental age. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Background: While postoperative myocardial injury remains a major driver of morbidity and mortality, the ability to accurately identify patients at risk remains limited despite decades of clinical research. The role of genetic information in predicting myocardial injury after noncardiac surgery (MINS) remains unknown and requires large scale electronic health record and genomic data sets. Methods: In this retrospective observational study of adult patients undergoing noncardiac surgery, we defined MINS as new troponin elevation within 30 days following surgery. To determine the incremental value of polygenic risk score (PRS) for coronary artery disease, we added the score to 3 models of MINS risk: revised cardiac risk index, a model comprised entirely of preoperative variables, and a model with combined preoperative plus intraoperative variables. We assessed performance without and with PRSs via area under the receiver operating characteristic curve and net reclassification index. Results: Among 90 053 procedures across 40 498 genotyped individuals, we observed 429 cases with MINS (0.5%). PRS for coronary artery disease was independently associated with MINS for each multivariable model created (odds ratio=1.12 [95% CI, 1.02–1.24], P =0.023 in the revised cardiac risk index-based model; odds ratio, 1.19 [95% CI, 1.07–1.31], P =0.001 in the preoperative model; and odds ratio, 1.17 [95% CI, 1.06–1.30], P =0.003 in the preoperative plus intraoperative model). The addition of clinical risk factors improved model discrimination. When PRS was included with preoperative and preoperative plus intraoperative models, up to 3.6% of procedures were shifted into a new outcome classification. Conclusions: The addition of a PRS does not significantly improve discrimination but remains independently associated with MINS and improves goodness of fit. As genetic analysis becomes more common, clinicians will have an opportunity to use polygenic risk to predict perioperative complications. Further studies are necessary to determine if PRSs can inform MINS surveillance.

Purpose Intraoperative hypoglycemia can result in devastating neurologic injury if not promptly diagnosed and treated. Few studies have defined risk factors for intraoperative hypoglycemia. The authors sought to characterize children with intraoperative hypoglycemia and determine independent risk factors. Methods This retrospective observational singleinstitution study included all patients \ 18 yr of age undergoing an anesthetic from January 1 2012 to December 31 2016. The primary outcome was blood glucose \ 3.3 mmolÁL-1 (60 mgÁdl-1). Data collected included patient characteristics, comorbidities, and intraoperative factors. A multivariable logistic regression model was used to identify independent predictors of intraoperative hypoglycemia. Results Blood glucose was measured in 7,715 of 73,592 cases with 271 (3.5%) having a glucose \ 3.3 mmolÁL-1 (60 mgÁdl-1). Young age, weight for age \ 5th percentile, developmental delay, presence of a gastric or jejunal tube, and abdominal surgery were identified as independent predictors for intraoperative hypoglycemia. Eighty percent of hypoglycemia cases occurred in children \ three years of age and in children \ 15 kg. Conclusion Young age, weight for age \ 5th percentile, developmental delay, having a gastric or jejunal tube, and abdominal surgery were independent risk factors for intraoperative hypoglycemia in children. Frequent

Background The relationship between intraoperative physiology and postoperative stroke is incompletely understood. Preliminary data suggest that either hypo- or hypercapnia coupled with reduced cerebrovascular inflow (e.g., due to hypotension) can lead to ischemia. This study tested the hypothesis that the combination of intraoperative hypotension and either hypo- or hypercarbia is associated with postoperative ischemic stroke. Methods We conducted a retrospective, case-control study via the Multicenter Perioperative Outcomes Group. Non-cardiac, non-intracranial, and non-major vascular surgical cases (age ≥18 years) were extracted from five major academic centers between January 2004 and December 2015. Ischemic stroke cases were identified via manual chart review and matched to controls (1:4). Time and reduction below key mean arterial blood pressure thresholds (<55 mmHg, <60 mmHg, <65 mmHg) and outside of specific end-tidal carbon dioxide thresholds (≤30 mmHg, ≤35 mmHg, ≥45 mmHg) were calculated based on total area under the curve. The association between stroke and total area under the curve values was then tested while adjusting for relevant confounders. Results In total, 1,244,881 cases were analyzed. Among the cases that screened positive for stroke (n=1,702), 126 were confirmed and successfully matched with 500 corresponding controls. Total area under the curve was significantly associated with stroke for all thresholds tested, with the strongest combination observed with MAP <55 mmHg (adjusted odds ratio per 10 mmHg-min, 1.17 [95% confidence interval, 1.10 – 1.23], p<0.0001) and end-tidal carbon dioxide ≥45 mmHg (adjusted odds ratio per 10 mmHg-min, 1.11 [95% confidence interval, 1.10 – 1.11], p<0.0001). There was no interaction effect observed between blood pressure and carbon dioxide. Conclusion Intraoperative hypotension and carbon dioxide dysregulation may each independently increase postoperative stroke risk.