Multicenter Perioperative Outcomes Group Research Articles

Determinants and practice variability of oxygen administration during surgery in the U.S., a retrospective cohort study.

The best approaches to supplemental oxygen administration during surgery remain unclear, which may contribute to variation in practice. We aimed to assess determinants of oxygen administration and its variability during surgery. Using multivariable linear mixed-effects regression, we measured the associations between intraoperative fraction of inspired oxygen and patient, procedure, medical center, anesthesiologist, and in-room anesthesia provider factors in surgical cases of 120 minutes or longer in adult patients who received general anesthesia with tracheal intubation and were admitted to the hospital after surgery between January 2016 and January 2019 at 42 medical centers across the U.S. participating in the Multicenter Perioperative Outcomes Group data registry. The sample included 367,841 cases (median [25 th, 75 th] age, 59 [47, 69] years; 51.1% women; 26.1% treated with nitrous oxide) managed by 3,836 anesthesiologists and 15,381 in-room anesthesia providers. Median (25 th, 75 th) fraction of inspired oxygen was 0.55 (0.48, 0.61), with 6.9% of cases <0.40 and 8.7% >0.90. Numerous patient and procedure factors were statistically associated with increased inspired oxygen, notably advanced ASA classification, heart disease, emergency surgery, and cardiac surgery, but most factors had little clinical significance (<1% inspired oxygen change). Overall, patient factors only explained 3.5% (95% CI, 3.5 to 3.5) of the variability in oxygen administration and procedure factors 4.4% (4.2 to 4.6). Anesthesiologist explained 7.7% (7.2 to 8.2) of the variability in oxygen administration, in-room anesthesia provider 8.1% (7.8 to 8.4), medical center 23.3% (22.4 to 24.2), and 53.0% (95% CI, 52.4 to 53.6) was unexplained. Among adults undergoing surgery with anesthesia and tracheal intubation, supplemental oxygen administration was variable and appeared arbitrary. Most patient and procedure factors had statistical but minor clinical associations with oxygen administration. Medical center and anesthesia provider explained significantly more variability in oxygen administration than patient or procedure factors.

Reduce intraoperative albumin utilisation in cardiac surgical patients: a quality improvement initiative

BackgroundAlbumin continues to be used routinely by cardiac anaesthesiologists perioperatively despite lack of evidence for improved outcomes. The Multicenter Perioperative Outcomes Group (MPOG) data ranked our institution as one of...

Variability in Intraoperative Opioid and Nonopioid Utilization During Intracranial Surgery: A Multicenter, Retrospective Cohort Study.

Key goals during intracranial surgery are to facilitate rapid emergence and extubation for early neurologic evaluation. Longer-acting opioids are often avoided or administered at subtherapeutic doses due to their perceived risk of sedation and delayed emergence. However, inadequate analgesia and increased postoperative pain are common after intracranial surgery. In this multicenter study, we describe variability in opioid and nonopioid administration patterns in patients undergoing intracranial surgery. This was a multicenter, retrospective observational cohort study using the Multicenter Perioperative Outcomes Group database. Opioid and nonopioid practice patterns in 31,217 cases undergoing intracranial surgery across 11 institutions in the United States are described. Across all 11 institutions, total median [interquartile range] oral morphine equivalents, normalized to weight and anesthesia duration was 0.17 (0.08 to 0.3) mg.kg.min-1. There was a 7-fold difference in oral morphine equivalents between the lowest (0.05 [0.02 to 0.13] mg.kg.min-1) and highest (0.36 [0.18 to 0.54] mg.kg.min-1) prescribing institutions. Patients undergoing supratentorial surgery had higher normalized oral morphine equivalents compared with those having infratentorial surgery [0.17 [0.08-0.31] vs. 0.15 [0.07-0.27] mg/kg/min-1; P<0.001); however, this difference is clinically small. Nonopioid analgesics were not administered in 20% to 96.8% of cases across institutions. This study found wide variability for both opioid and nonopioid utilization at an institutional level. Future work on practitioner-level opioid and nonopioid use and its impact on outcomes after intracranial surgery should be conducted.

AcumenTM hypotension prediction index guidance for prevention and treatment of hypotension in noncardiac surgery: a prospective, single-arm, multicenter trial

BackgroundIntraoperative hypotension is common during noncardiac surgery and is associated with postoperative myocardial infarction, acute kidney injury, stroke, and severe infection. The Hypotension Prediction Index software is an algorithm based on arterial waveform analysis that alerts clinicians of the patient’s likelihood of experiencing a future hypotensive event, defined as mean arterial pressure < 65 mmHg for at least 1 min.MethodsTwo analyses included (1) a prospective, single-arm trial, with continuous blood pressure measurements from study monitors, compared to a historical comparison cohort. (2) A post hoc analysis of a subset of trial participants versus a propensity score-weighted contemporaneous comparison group, using external data from the Multicenter Perioperative Outcomes Group (MPOG). The trial included 485 subjects in 11 sites; 406 were in the final effectiveness analysis. The post hoc analysis included 457 trial participants and 15,796 comparison patients. Patients were eligible if aged 18 years or older, American Society of Anesthesiologists (ASA) physical status 3 or 4, and scheduled for moderate- to high-risk noncardiac surgery expected to last at least 3 h. Measurements: minutes of mean arterial pressure (MAP) below 65 mmHg and area under MAP < 65 mmHg.ResultsAnalysis 1: Trial subjects (n = 406) experienced a mean of 9 ± 13 min of MAP below 65 mmHg, compared with the MPOG historical control mean of 25 ± 41 min, a 65% reduction (p < 0.001). Subjects with at least one episode of hypotension (n = 293) had a mean of 12 ± 14 min of MAP below 65 mmHg compared with the MPOG historical control mean of 28 ± 43 min, a 58% reduction (p< 0.001). Analysis 2: In the post hoc inverse probability treatment weighting model, patients in the trial demonstrated a 35% reduction in minutes of hypotension compared to a contemporaneous comparison group [exponentiated coefficient: − 0.35 (95%CI − 0.43, − 0.27); p < 0.001].ConclusionsThe use of prediction software for blood pressure management was associated with a clinically meaningful reduction in the duration of intraoperative hypotension. Further studies must investigate whether predictive algorithms to prevent hypotension can reduce adverse outcomes.Trial registrationClinical trial number: NCT03805217. Registry URL: https://clinicaltrials.gov/ct2/show/NCT03805217. Principal investigator: Xiaodong Bao, MD, PhD. Date of registration: January 15, 2019.

The Association of Guideline-Directed Prophylaxis With Postoperative Nausea and Vomiting in Adult Patients: A Single-Center, Retrospective Cohort Study.

Consensus guidelines for postoperative nausea and vomiting (PONV) prophylaxis recommend a risk-based approach in which the number of antiemetics administered is based on a preoperative estimate of PONV risk. These guidelines have been adapted by the Multicenter Perioperative Outcomes Group (MPOG) to serve as measures of clinician and hospital compliance with guideline-recommended care. However, the impact of this approach on clinical outcomes is not known. We performed a single-center, retrospective study of adult patients undergoing general anesthesia from 2018 to 2021. Risk factors for PONV were defined using MPOG definitions: female sex, history of PONV or motion sickness, nonsmoker, inhaled anesthesia >60 minutes, high-risk procedure (cholecystectomy, laparoscopic, gynecologic), and age <50 years. Adequate prophylaxis was defined using the MPOG PONV-05 metric: at least 2 agents for patients with 1 to 2 risk factors and at least 3 agents for patients with 3+ risk factors. PONV was defined as documented PONV or receipt of rescue antiemetics. To estimate the association between adequate prophylaxis and PONV, we used Bayesian binomial models with overlap propensity score weighting. We included 76,703 cases (43% receiving adequate prophylaxis) with PONV occurring in 19%. In unadjusted and unweighted comparison, adequate prophylaxis was associated with increased incidence of PONV: median odds ratio 1.21 (95% credible interval [1.16-1.25]). However, after propensity score weighting and multivariable adjustment, adequate prophylaxis was associated with reduced relative and absolute risk for PONV: weighted marginal median odds ratio 0.90 [0.84-0.98] and absolute risk reduction (ARR) 1.6% [0.6%-2.6%]. There was evidence for a differential effect of adequate prophylaxis across the guideline-defined risk spectrum, with benefit seen in patients with 1 to 5 risk factors (conditional probabilities of benefit >0.81), but not in those at high predicted risk. Patient-specific, covariate-adjusted ARR was heterogeneous, with a median patient-specific conditional probability of benefit of 0.84 (95% credible interval, 0.73-0.90). Guideline-directed PONV prophylaxis is associated with a modest reduction in PONV, although this effect is small and heterogeneous on the absolute scale. We found evidence for a differential association between adequate prophylaxis and PONV across the guideline-defined risk spectrum, with diminution in patients at very high predicted preoperative risk. While patient-specific benefit was heterogenous, most patients had reasonably high predicted probabilities of absolute benefit from a guideline-directed strategy. Further assessment of these associations in a multicenter setting, with more robust investigation of risk prediction methods will allow for better understanding of the optimal approach to PONV prophylaxis.

Factors Associated With Decision to Use and Dosing of Sugammadex in Children: A Retrospective Cross-Sectional Observational Study.

Sugammadex was initially approved for reversal of neuromuscular blockade in adults in the United States in 2015. Limited data suggest sugammadex is widely used in pediatric anesthesia practice however the factors influencing use are not known. We explore patient, surgical, and institutional factors associated with the decision to use sugammadex versus neostigmine or no reversal, and the decision to use 2 mg/kg vs 4 mg/kg dosing. Using data from the Multicenter Perioperative Outcomes Group (MPOG) database, an EHR-derived registry, we conducted a retrospective cross-sectional study. Eligible cases were performed between January 1, 2016 and December 31, 2020, for children 0 to 17 years at US hospitals. Cases involved general anesthesia with endotracheal intubation and administration of rocuronium or vecuronium. Using generalized linear mixed models with institution and anesthesiologist-specific random intercepts, we measured the importance of a variety of patient, clinician, institution, anesthetic, and surgical risk factors in the decision to use sugammadex versus neostigmine, and the decision to use a 2 mg/kg vs 4 mg/kg dose. We then used intraclass correlation statistics to evaluate the proportion of variance contributed by institution and anesthesiologist specifically. There were 97,654 eligible anesthetics across 30 institutions. Of these 47.1% received sugammadex, 43.1% received neostigmine, and 9.8% received no reversal agent. Variability in the choice to use sugammadex was attributable primarily to institution (40.4%) and attending anesthesiologist (27.1%). Factors associated with sugammadex use (compared to neostigmine) include time from first institutional use of sugammadex (odds ratio [OR], 1.08, 95% confidence interval [CI], 1.08-1.09, per month, P < .001), younger patient age groups (0-27 days OR, 2.59 [2.00-3.34], P < .001; 28 days-1 year OR, 2.72 [2.16-3.43], P < .001 vs 12-17 years), increased American Society of Anesthesiologists [ASA] physical status (ASA III: OR, 1.32 [1.23-1.42], P < .001 ASA IV OR, 1.71 [1.46-2.00], P < .001 vs ASA I), neuromuscular disease (OR, 1.14 (1.04-1.26], P = .006), cardiac surgery (OR, 1.76 [1.40-2.22], P < .001), dose of neuromuscular blockade within the hour before reversal (>2 ED95s/kg OR, 4.58 (4.14-5.07], P < .001 vs none), and shorter case duration (case duration <60 minutes OR, 2.06 [1.75-2.43], P < .001 vs >300 minutes). Variation in sugammadex use was primarily explained by institution and attending anesthesiologist. Patient factors associated with the decision to use sugammadex included younger age, higher doses of neuromuscular blocking agents, and increased medical complexity.

Hypoxemia in School Age Children Undergoing One-Lung Ventilation: A Retrospective Cohort Study from the Multicenter Perioperative Outcomes Group (MPOG).

Risk factors for hypoxemia in school age children undergoing one-lung ventilation remain poorly understood. We hypothesize that certain modifiable and non-modifiable factors may be associated with increased risk of hypoxemia in school age children undergoing one-lung ventilation and thoracic surgery. The Multicenter Perioperative Outcomes Group database was queried for children 4 to 17 years of age undergoing one-lung ventilation. Patients undergoing vascular or cardiac procedures were excluded. The original cohort was divided into two cohorts: 4-9 and 10-17 years of age inclusive. All records were reviewed electronically for the primary outcome of hypoxemia during one-lung ventilation defined as an oxygen saturation (SpO2)<90% for≥3 minutes continuously and severe hypoxemia, SpO2<90% for ≥5 minutes. Potential modifiable and non-modifiable risk factors associated with these outcomes were evaluated using separate multivariable least absolute shrinkage and selection operator regression analyses for each cohort. Covariates evaluated included: age, extremes of weight, American Society of Anesthesiologists Physical Status≥3, duration of one-lung ventilation, preoperative SpO2<98%, approach to one lung ventilation, right operative side, video assisted thoracoscopic surgery, lower tidal volume ventilation defined as tidal volume≤6ml/kg + positive end expiratory pressure ≥ 4cmH2O >80% of the duration of one-lung ventilation, and procedure type. The prevalence of hypoxemia in the 4-9 and 10-17 year old cohorts was 24/228 (10.5%, 95%CI[6.5%-14.5%]) and 76/1012 (7.5%, 95%CI[5.9%-9.1%]) respectively. The prevalence of severe hypoxemia in both cohorts was 14/228 (6.1%, 95%CI[3.0%-9.3%]) and 47/1012 (4.6%, 95%CI[3.3%-5.8%]). Initial SpO2<98% was associated with hypoxemia in the 4-9 year old cohort, OR 4.20 [95%CI(1.61 - 6.29)]. Initial SpO2<98%, OR 2.76[95%CI(1.69-4.48)], extremes of weight, OR 2.18[95%CI(1.29-3.61)], right sided cases, OR 2.33[95%CI(1.41-3.92)], were associated with an increased risk of hypoxemia in the older cohort. Increasing age (1 year increment), OR 0.88[95%CI(0.80-0.97)] was associated with a decreased risk of hypoxemia. An initial room air oxygen saturation <98% was associated with an increased risk of hypoxemia in all children 4-17 years of age. Extremes of weight, right sided cases, and decreasing age were associated with an increased risk of hypoxemia in children 10-17 years of age.

The Association of Guideline-Directed Prophylaxis with Postoperative Nausea and Vomiting in Pediatric Patients: A Single-Center, Retrospective Cohort Study.

Guidelines for postoperative nausea and vomiting (PONV) prophylaxis in pediatric patients recommend escalation of the number of antiemetics based on a preoperative estimate of PONV risk. These recommendations have been translated into performance metrics, most notably by the Multicenter Perioperative Outcomes Group (MPOG), used at over 25 children's hospitals. The impact of this approach on clinical outcomes is not known. We performed a single-center, retrospective study of pediatric general anesthetic cases from 2018 to 2021. PONV risk factors were defined using MPOG definitions: age ≥3 years, volatile use ≥30 minutes, PONV history, long-acting opioids, female ≥12 years, and high-risk procedure. Adequate prophylaxis was defined using the MPOG PONV-04 metric: 1 agent for 1 risk factor, 2 agents for 2 risk factors, and 3 agents for 3+ risk factors. PONV was defined as documented postoperative nausea/emesis or administration of a rescue antiemetic. Given the nonrandomized allocation of adequate prophylaxis, we used Bayesian binomial models with propensity score weighting. A total of 14,747 cases were included, with PONV in 11% (9% adequate prophylaxis versus 12% inadequate). Overall, there was evidence for reduced incidence of PONV with adequate prophylaxis: weighted median odds ratio 0.82 (95% credible interval, 0.66-1.02; probability of benefit, 0.97) and weighted marginal absolute risk reduction 1.3% (-0.1% to 3.1%). In unweighted estimates, there was an interaction between sum of risk factors and the association of adequate prophylaxis with PONV, with reduced incidence in patients with 1 to 2 risk factors (probability of benefit 0.96 and 0.95) but increased incidence in patients with 3+ risk factors receiving adequate prophylaxis (probability of benefit 0, 0.01, and 0.03 for 3, 4, and 5 risk factors). This was attenuated by weighting, with persistent benefit in 1 to 2 risk factors (probability of benefit 0.90 and 0.94) but equalization of risk in 3+ risk factors. Guideline-directed PONV prophylaxis is inconsistently associated with incidence of PONV across the guideline-defined risk spectrum. This phenomenon, and its attenuation with weighting, is consistent with 2 points: dichotomous risk-factor summation ignores differential effects of individual components, and prognostic information might exist beyond these risk factors. PONV risk at a given sum of risk factors is not homogeneous, but rather is determined by the unique composition of risk factors and other prognostic attributes. These differences appear to have been identified by clinicians, prompting use of more antiemetics. Even after accounting for these differences, however, addition of a third agent did not further reduce risk.

Cardiometabolic disease and obesity patterns differentially predict acute kidney injury after total joint replacement: a retrospective analysis

BackgroundAcute kidney injury (AKI) is a frequent yet understudied postoperative total joint arthroplasty complication. This study aimed to describe cardiometabolic disease co-occurrence using latent class analysis, and associated postoperative AKI risk. MethodsThis retrospective analysis examined patients ≥18 years old undergoing primary total knee or hip arthroplasties within the US Multicenter Perioperative Outcomes Group of hospitals from 2008 to 2019. AKI was defined using modified Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Latent classes were constructed from eight cardiometabolic diseases including hypertension, diabetes, and coronary artery disease, excluding obesity. A mixed-effects logistic regression model was constructed for the outcome of any AKI and the exposure of interaction between latent class and obesity status adjusting for preoperative and intraoperative covariates. ResultsOf 81 639 cases, 4007 (4.9%) developed AKI. Patients with AKI were more commonly older and non-Hispanic Black, with more significant comorbidity. A latent class model selected three groups of cardiometabolic patterning, labelled ‘hypertension only’ (n=37 223), ‘metabolic syndrome (MetS)’ (n=36 503), and ‘MetS+cardiovascular disease (CVD)’ (n=7913). After adjustment, latent class/obesity interaction groups had differential risk of AKI compared with those in ‘hypertension only’/non-obese. Those ‘hypertension only’/obese had 1.7-fold increased odds of AKI (95% confidence interval [CI]: 1.5–2.0). Compared with ‘hypertension only’/non-obese, those ‘MetS+CVD’/obese had the highest odds of AKI (odds ratio 3.1, 95% CI: 2.6–3.7), whereas ‘MetS+CVD’/non-obese had 2.2 times the odds of AKI (95% CI: 1.8–2.7; model area under the curve 0.76). ConclusionsThe risk of postoperative AKI varies widely between patients. The current study suggests that the co-occurrence of metabolic conditions (diabetes mellitus, hypertension), with or without obesity, is a more important risk factor for acute kidney injury than individual comorbid diseases.

Carbon Dioxide, Blood Pressure, and Stroke: Reply.

Carbon Dioxide, Blood Pressure, and Stroke: Reply.

Hyperoxemia During Cardiac Surgery Is Associated With Postoperative Pulmonary Complications.

Retrospective cohort study. We analyzed intraoperative data from five hospitals within the Multicenter Perioperative Outcomes Group between January 1, 2014, and December 31, 2019. We assessed intraoperative oxygenation of adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). Hyperoxemia pre and post CPB was quantified as the area under the curve (AUC) of Fio2 above 0.21 in minutes when the corresponding peripheral oxygen saturation was greater than 92% measured by pulse oximetry. We quantified hyperoxemia during CPB as the AUC of Pao2 greater than 200 mm Hg measured by arterial blood gas. We analyzed the association of hyperoxemia during all phases of cardiac surgery with the frequency of postoperative pulmonary complications within 30 days, including acute respiratory insufficiency or failure, acute respiratory distress syndrome, need for reintubation, and pneumonia. Twenty-one thousand six hundred thirty-two cardiac surgical patients. None. During 21,632 distinct cardiac surgery cases, 96.4% of patients spent at least 1 minute in hyperoxemia (99.1% pre-CPB, 98.5% intra-CPB, and 96.4% post-CPB). Increasing exposure to hyperoxemia was associated with an increased risk of postoperative pulmonary complications throughout three distinct surgical periods. During CPB, increasing exposure to hyperoxemia was associated with an increased odds of developing postoperative pulmonary complications (p < 0.001) in a linear manner. Hyperoxemia before CPB (p < 0.001) and after CPB (p = 0.02) were associated with increased odds of developing postoperative pulmonary complications in a U-shaped relationship. Hyperoxemia occurs almost universally during cardiac surgery. Exposure to hyperoxemia assessed continuously as an AUC during the intraoperative period, but particularly during CPB, was associated with an increased incidence of postoperative pulmonary complications.

Association of Anesthesiologist Staffing Ratio with Surgical Patient Morbidity and Mortality

Article| January 2023 Association of Anesthesiologist Staffing Ratio with Surgical Patient Morbidity and Mortality Amr E. Abouleish, MD, MBA, FASA Amr E. Abouleish, MD, MBA, FASA Search for other works by this author on: This Site PubMed Google Scholar ASA Monitor January 2023, Vol. 87, 28. https://doi.org/10.1097/01.ASM.0000911780.00940.57 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Search Site Citation Amr E. Abouleish; Association of Anesthesiologist Staffing Ratio with Surgical Patient Morbidity and Mortality. ASA Monitor 2023; 87:28 doi: https://doi.org/10.1097/01.ASM.0000911780.00940.57 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll PublicationsASA Monitor Search Advanced Search Topics: morbidity, mortality, personnel staffing and scheduling, surgical procedures, operative In the wake of news coverage and studies examining surgeons with overlapping surgical procedures and patient outcomes, Burns et al. examined anesthesiologists covering overlapping anesthesia cases and the staffing ratio impact on patient outcomes in this retrospective, matched cohort study of major noncardiac inpatient surgical procedures done in 23 U.S. academic and private hospitals (JAMA Surg 2022;157:807-15). The study used the Multicenter Perioperative Outcomes Group (MPOG) database, which is populated directly from the electronic medical records, including anesthesia records (asamonitor.pub/3ftbeZt). Only cases where the anesthesiologist working with one to four nurse anesthetists at same time were included. (Cases where an anesthesiology resident was in the case >25% of time were excluded.) Propensity score-matching methods were applied. Staffing ratio was based on the anesthesiologist in the staffing grid of the electronic record. The staffing ratio was a weighted average of the staffing ratios throughout the anesthesia case... You do not currently have access to this content.

Intraoperative Use of Albumin in Major Noncardiac Surgery: Incidence, Variability, and Association With Outcomes.

The impact of albumin use during major surgery is unknown, and a dearth of evidence governing its use in major noncardiac surgery has long precluded its standardization in clinical guidelines. In this study, we investigate institutional variation in albumin use among medical centers in the United States during major noncardiac surgery and explore the association of intraoperative albumin administration with important postoperative outcomes. The study is an observational retrospective cohort analysis performed among 54 U.S. hospitals in the Multicenter Perioperative Outcomes Group and includes adult patients who underwent major noncardiac surgery under general anesthesia between January 2014 and June 2020. The primary endpoint was the incidence of albumin administration. Secondary endpoints are acute kidney injury (AKI), net-positive fluid balance, pulmonary complications, and 30-day mortality. Albumin-exposed and albumin-unexposed cases were compared within a propensity score-matched cohort to evaluate associations of albumin use with outcomes. Among 614,215 major surgeries, predominantly iso-oncotic albumin was administered in 15.3% of cases and featured significant inter-institutional variability in use patterns. Cases receiving intraoperative albumin involved patients of higher American Society of Anesthesiologists physical status and featured larger infused crystalloid volumes, greater blood loss, and vasopressor use. Overall, albumin was most often administered at high-volume surgery centers with academic affiliation, and within a propensity score-matched cohort (n=153,218), the use of albumin was associated with AKI (aOR 1.24, 95% CI 1.20-1.28, P <0.001), severe AKI (aOR 1.45, 95% CI 1.34-1.56, P <0.001), net-positive fluid balance (aOR 1.18, 95% CI 1.16-1.20, P <0.001), pulmonary complications (aOR 1.56, 95% CI 1.30-1.86, P <0.001), and 30-day all-cause mortality (aOR 1.37, 95% CI 1.26-1.49, P <0.001). Intravenous albumin is commonly administered among noncardiac surgeries with significant inter-institutional variability in use in the United States. Albumin administration was associated with an increased risk of postoperative complications.

Oxygen administration during surgery and postoperative organ injury: observational cohort study

ObjectiveTo examine whether supraphysiological oxygen administration during surgery is associated with lower or higher postoperative kidney, heart, and lung injury.DesignObservational cohort study.Setting42 medical centers across the United States participating in...

Time-of-day dependent effects of midazolam administration on myocardial injury in non-cardiac surgery.

Animal studies have shown that midazolam can increase vulnerability to cardiac ischemia, potentially via circadian-mediated mechanisms. We hypothesized that perioperative midazolam administration is associated with an increased incidence of myocardial injury in patients undergoing non-cardiac surgery (MINS) and that circadian biology may underlie this relationship. We analyzed intraoperative data from the Multicenter Perioperative Outcomes Group for the occurrence of MINS across 50 institutions from 2014 to 2019. The primary outcome was the occurrence of MINS. MINS was defined as having at least one troponin-I lab value ≥0.03 ng/ml from anesthesia start to 72 h after anesthesia end. To account for bias, propensity scores and inverse probability of treatment weighting were applied. A total of 1,773,118 cases were available for analysis. Of these subjects, 951,345 (53.7%) received midazolam perioperatively, and 16,404 (0.93%) met criteria for perioperative MINS. There was no association between perioperative midazolam administration and risk of MINS in the study population as a whole (odds ratio (OR) 0.98, confidence interval (CI) [0.94, 1.01]). However, we found a strong association between midazolam administration and risk of MINS when surgery occurred overnight (OR 3.52, CI [3.10, 4.00]) or when surgery occurred in ASA 1 or 2 patients (OR 1.25, CI [1.13, 1.39]). Perioperative midazolam administration may not pose a significant risk for MINS occurrence. However, midazolam administration at night and in healthier patients could increase MINS, which warrants further clinical investigation with an emphasis on circadian biology.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Demonstration and Performance Evaluation of Two Novel Algorithms for Removing Artifacts From Automated Intraoperative Temperature Data Sets: Multicenter, Observational, Retrospective Study.

BackgroundThe automated acquisition of intraoperative patient temperature data via temperature probes leads to the possibility of producing a number of artifacts related to probe positioning that may impact these probes’ utility for observational research.ObjectiveWe sought to compare the performance of two de novo algorithms for filtering such artifacts.MethodsIn this observational retrospective study, the intraoperative temperature data of adults who received general anesthesia for noncardiac surgery were extracted from the Multicenter Perioperative Outcomes Group registry. Two algorithms were developed and then compared to the reference standard—anesthesiologists’ manual artifact detection process. Algorithm 1 (a slope-based algorithm) was based on the linear curve fit of 3 adjacent temperature data points. Algorithm 2 (an interval-based algorithm) assessed for time gaps between contiguous temperature recordings. Sensitivity and specificity values for artifact detection were calculated for each algorithm, as were mean temperatures and areas under the curve for hypothermia (temperatures below 36 °C) for each patient, after artifact removal via each methodology.ResultsA total of 27,683 temperature readings from 200 anesthetic records were analyzed. The overall agreement among the anesthesiologists was 92.1%. Both algorithms had high specificity but moderate sensitivity (specificity: 99.02% for algorithm 1 vs 99.54% for algorithm 2; sensitivity: 49.13% for algorithm 1 vs 37.72% for algorithm 2; F-score: 0.65 for algorithm 1 vs 0.55 for algorithm 2). The areas under the curve for time × hypothermic temperature and the mean temperatures recorded for each case after artifact removal were similar between the algorithms and the anesthesiologists.ConclusionsThe tested algorithms provide an automated way to filter intraoperative temperature artifacts that closely approximates manual sorting by anesthesiologists. Our study provides evidence demonstrating the efficacy of highly generalizable artifact reduction algorithms that can be readily used by observational studies that rely on automated intraoperative data acquisition.

Science, Medicine, and the Anesthesiologist

Science, Medicine, and the Anesthesiologist

Carbon Dioxide, Blood Pressure, and Perioperative Stroke: A Retrospective Case-Control Study.

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. We conducted a retrospective, case-control study via the Multicenter Perioperative Outcomes Group. Noncardiac, nonintracranial, and nonmajor vascular surgical cases (18 yr or older) 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 (less than 55 mmHg, less than 60 mmHg, less than 65 mmHg) and outside of specific end-tidal carbon dioxide thresholds (30 mmHg or less, 35 mmHg or less, 45 mmHg or greater) 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. 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 mean arterial pressure less than 55 mmHg (adjusted odds ratio per 10 mmHg-min, 1.17 [95% CI, 1.10 to 1.23], P < 0.0001) and end-tidal carbon dioxide 45 mmHg or greater (adjusted odds ratio per 10 mmHg-min, 1.11 [95% CI, 1.10 to 1.11], P < 0.0001). There was no interaction effect observed between blood pressure and carbon dioxide. Intraoperative hypotension and carbon dioxide dysregulation may each independently increase postoperative stroke risk.

Association of Anesthesiologist Staffing Ratio With Surgical Patient Morbidity and Mortality

Recent studies have investigated the effect of overlapping surgeon responsibilities or nurse to patient staffing ratios on patient outcomes, but the association of overlapping anesthesiologist responsibilities with patient outcomes remains unexplored to our knowledge. To examine the association between different levels of anesthesiologist staffing ratios and surgical patient morbidity and mortality. A retrospective, matched cohort study consisting of major noncardiac inpatient surgical procedures performed from January 1, 2010, to October 31, 2017, was conducted in 23 US academic and private hospitals. A total of 866 453 adult patients (aged ≥18 years) undergoing major inpatient surgery within the Multicenter Perioperative Outcomes Group electronic health record registry were included. Anesthesiologist sign-in and sign-out times were used to calculate a continuous time-weighted average staffing ratio variable for each operation. Propensity score-matching methods were applied to create balanced sample groups with respect to patient-, operative-, and hospital-level confounders and resulted in 4 groups based on anesthesiologist staffing ratio. Groups consisted of patients receiving care from an anesthesiologist covering 1 operation (group 1), more than 1 to no more than 2 overlapping operations (group 1-2), more than 2 to no more than 3 overlapping operations (group 2-3), and more than 3 to no more than 4 overlapping operations (group 3-4). Data analysis was performed from October 2019 to October 2021. Undergoing a major inpatient surgical operation that involved an anesthesiologist providing care for up to 4 overlapping operations. The primary composite outcome was 30-day mortality and 6 major surgical morbidities (cardiac, respiratory, gastrointestinal, urinary, bleeding, and infectious complications) derived from International Classification of Diseases, Ninth Revision and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision discharge diagnosis codes. In all, 578 815 adult patients (mean [SD] age, 55.7 [16.2] years; 55.1% female) were analyzed. After matching operations according to anesthesiologist staffing ratio, 48 555 patients were in group 1; 247 057, group 1-2; 216 193, group 2-3; and 67 010, group 3-4. Increasing anesthesiologist coverage responsibilities was associated with an increase in risk-adjusted surgical patient morbidity and mortality. Compared with patients in group 1-2, those in group 2-3 had a 4% relative increase in risk-adjusted mortality and morbidity (5.06% vs 5.25%; adjusted odds ratio [AOR], 1.04; 95% CI, 1.01-1.08; P = .02) and those in group 3-4 had a 14% increase in risk-adjusted mortality and morbidity (5.06% vs 5.75%; AOR, 1.15; 95% CI, 1.09-1.21; P < .001). This study's findings suggest that increasing overlapping coverage by anesthesiologists is associated with increased surgical patient morbidity and mortality. Therefore, the potential effects of staffing ratios in perioperative team models should be considered in clinical coverage efforts.