Bradley A. Fritz

Intraoperative Electroencephalogram Suppression Predicts Postoperative Delirium.

BACKGROUND:Postoperative delirium is a common complication associated with increased morbidity and mortality, longer hospital stays, and greater health care expenditures. Intraoperative electroencephalogram (EEG) slowing has been associated previously with postoperative delirium, but the relationship between intraoperative EEG suppression and postoperative delirium has not been investigated. METHODS:In this observational cohort study, 727 adult patients who received general anesthesia with planned intensive care unit admission were included. Duration of intraoperative EEG suppression was recorded from a frontal EEG channel (FP1 to F7). Delirium was assessed twice daily on postoperative days 1 through 5 with the Confusion Assessment Method for the intensive care unit. Thirty days after surgery, quality of life, functional independence, and cognitive ability were measured using the Veterans RAND 12-item survey, the Barthel index, and the PROMIS Applied Cognition-Abilities-Short Form 4a survey. RESULTS:Postoperative delirium was observed in 162 (26%) of 619 patients assessed. When we compared patients with no EEG suppression with those divided into quartiles based on duration of EEG suppression, patients with more suppression were more likely to experience delirium (&khgr;2(4) = 25, P < 0.0001). This effect remained significant after we adjusted for potential confounders (odds ratio for log(EEG suppression) 1.22 [99% confidence interval, 1.06–1.40, P = 0.0002] per 1-minute increase in suppression). EEG suppression may have been associated with reduced functional independence (Spearman partial correlation coefficient −0.15, P = 0.02) but not with changes in quality of life or cognitive ability. Predictors of EEG suppression included greater end-tidal volatile anesthetic concentration and lower intraoperative opioid dose. CONCLUSIONS:EEG suppression is an independent risk factor for postoperative delirium. Future studies should investigate whether anesthesia titration to minimize EEG suppression decreases the incidence of postoperative delirium. This is a substudy of the Systematic Assessment and Targeted Improvement of Services Following Yearlong Surgical Outcomes Surveys (SATISFY-SOS) surgical outcomes registry (NCT02032030).

Intraoperative ketamine for prevention of postoperative delirium or pain after major surgery in older adults: an international, multicentre, double-blind, randomised clinical trial

Background Delirium and pain are common and serious postoperative complications. Subanaesthetic ketamine is often administered intraoperatively for postoperative analgesia and to spare postoperative opioids. Some evidence also suggests that ketamine prevents delirium. The primary purpose of this trial was to evaluate the effectiveness of ketamine in preventing postoperative delirium in older adults after major surgery. Secondary outcomes, viewed as strongly related to delirium, were postoperative pain and opioid consumption. Methods This was a multicentre, international, randomised trial that enrolled adults older than 60 undergoing major cardiac and noncardiac surgery under general anaesthesia. Participants were enrolled prior to surgery and gave written informed consent. We used a computer-generated randomisation sequence. Patients at study sites were randomised to one of three study groups in blocks of 15 to receive intraoperative administration of (i) placebo (intravenous normal saline), (ii) low dose ketamine (0.5 mg/kg) or (iii) high dose ketamine (1 mg/kg). Study drug was administered following induction of anaesthesia, prior to surgical incision. Participants, clinicians, and investigators were all masked to group assignment. Delirium and pain were assessed twice daily in the first three postoperative days using the Confusion Assessment Method and Visual Analog Scale, respectively. Postoperative opioid use was recorded, and hallucinations and nightmares were assessed. Analyses were performed by intention-to-treat and adverse events were evaluated. The Prevention of Delirium and Complications Associated with Surgical Treatments [PODCAST] trial is registered in clinicaltrials.gov; NCT01690988 Findings Between February 6, 2014 and June 26, 2016, 1360 patients assessed and 672 were randomised, with 222 in the placebo group, 227 in the low dose ketamine group, and 223 in the high dose ketamine group. There was no difference in postoperative delirium incidence between those in the combined ketamine groups and those who received placebo (19.45% vs. 19.82%, respectively; absolute difference, 0.36%; 95% CI, −6.07% to 7.38%; p=0.92). There were no significant differences among the three groups in maximum pain scores (p=0.88) or median opioid consumption (p=0.47) over time. There were more postoperative hallucinations (p=0.01) and nightmares (p=0.03) with escalating doses of ketamine. Adverse events (cardiovascular, renal, infectious, gastrointestinal, bleeding), whether viewed individually (P value for each >0.40) or collectively (82/222 [36.9%] in placebo group, 90/227 [39.6%] in low dose ketamine group, 91/223 in high dose ketamine group [40.8%]; P=0.69), did not differ significantly across the three groups. Interpretation The administration of a single subanaesthetic dose of ketamine to older adults during major surgery did not show evidence of reducing postoperative delirium, pain, or opioid consumption, and might cause harm by inducing negative experiences. Given current evidence and guidelines related to ketamine and postoperative analgesia, the unexpected secondary findings regarding pain and opioid consumption warrant replication or refutation in subsequent research. Funding The funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The principal investigators (MSA and GAM) had full access to all the data in the study and had final responsibility for the decision to submit for publication.

Postoperative recovery with bispectral index versus anesthetic concentration-guided protocols

Background:Use of the bispectral index (BIS) monitor has been suggested to decrease excessive anesthetic drug administration, leading to improved recovery from general anesthesia. The purpose of this substudy of the B-Unawareand BAG-RECALL trials was to assess whether a BIS-based anesthetic protocol was superior to an end-tidal anesthetic concentration–based protocol in decreasing recovery time and postoperative complications. Methods:Patients at high risk for awareness were randomized to either BIS-guided or end-tidal anesthetic concentration–guided general anesthesia in the original trials. Outcomes included time to postanesthesia care unit discharge readiness, time to achieve a postoperative Aldrete score of 9–10, intensive care unit length of stay, postoperative nausea and vomiting, and severe postoperative pain. Univariate Cox regression and chi-square tests were used for statistical analyses. Results:The BIS cohort was not superior in time to postanesthesia care unit discharge readiness (hazard ratio, 1.0; 95% CI, 1.0–1.1; n = 2,949), time to achieve an Aldrete score of 9–10 (hazard ratio, 1.2; 95% CI, 1.0–1.4; n = 706), intensive care unit length of stay (hazard ratio, 1.0; 95% CI, 0.9–1.1; n = 2,074), incidence of postoperative nausea and vomiting (absolute risk reduction, −0.5%; 95% CI, −5.8 to 4.8%; n = 789), or incidence of severe postoperative pain (absolute risk reduction, 4.4%; 95% CI, −2.3 to 11.1%; n = 759). Conclusions:In patients at high risk for awareness, the BIS-guided protocol is not superior to an anesthetic concentration–guided protocol in time needed for postoperative recovery or in the incidences of common postoperative complications.

The Prevention of Delirium and Complications Associated with Surgical Treatments (PODCAST) study: protocol for an international multicentre randomised controlled trial

Introduction Postoperative delirium is one of the most common complications of major surgery, affecting 10–70% of surgical patients 60 years and older. Delirium is an acute change in cognition that manifests as poor attention and illogical thinking and is associated with longer intensive care unit (ICU) and hospital stay, long-lasting cognitive deterioration and increased mortality. Ketamine has been used as an anaesthetic drug for over 50 years and has an established safety record. Recent research suggests that, in addition to preventing acute postoperative pain, a subanaesthetic dose of intraoperative ketamine could decrease the incidence of postoperative delirium as well as other neurological and psychiatric outcomes. However, these proposed benefits of ketamine have not been tested in a large clinical trial. Methods The Prevention of Delirium and Complications Associated with Surgical Treatments (PODCAST) study is an international, multicentre, randomised controlled trial. 600 cardiac and major non-cardiac surgery patients will be randomised to receive ketamine (0.5 or 1 mg/kg) or placebo following anaesthetic induction and prior to surgical incision. For the primary outcome, blinded observers will assess delirium on the day of surgery (postoperative day 0) and twice daily from postoperative days 1–3 using the Confusion Assessment Method or the Confusion Assessment Method for the ICU. For the secondary outcomes, blinded observers will estimate pain using the Behavioral Pain Scale or the Behavioral Pain Scale for Non-Intubated Patients and patient self-report. Ethics and dissemination The PODCAST trial has been approved by the ethics boards of five participating institutions; approval is ongoing at other sites. Recruitment began in February 2014 and will continue until the end of 2016. Dissemination plans include presentations at scientific conferences, scientific publications, stakeholder engagement and popular media. Registration details The study is registered at clinicaltrials.gov, NCT01690988 (last updated March 2014). The PODCAST trial is being conducted under the auspices of the Neurological Outcomes Network for Surgery (NEURONS). Trial registration number NCT01690988 (last updated December 2013).

Protocol for the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) study: a pragmatic, randomised clinical trial

Introduction Postoperative delirium, arbitrarily defined as occurring within 5 days of surgery, affects up to 50% of patients older than 60 after a major operation. This geriatric syndrome is associated with longer intensive care unit and hospital stay, readmission, persistent cognitive deterioration and mortality. No effective preventive methods have been identified, but preliminary evidence suggests that EEG monitoring during general anaesthesia, by facilitating reduced anaesthetic exposure and EEG suppression, might decrease incident postoperative delirium. This study hypothesises that EEG-guidance of anaesthetic administration prevents postoperative delirium and downstream sequelae, including falls and decreased quality of life. Methods and analysis This is a 1232 patient, block-randomised, double-blinded, comparative effectiveness trial. Patients older than 60, undergoing volatile agent-based general anaesthesia for major surgery, are eligible. Patients are randomised to 1 of 2 anaesthetic approaches. One group receives general anaesthesia with clinicians blinded to EEG monitoring. The other group receives EEG-guidance of anaesthetic agent administration. The outcomes of postoperative delirium (≤5 days), falls at 1 and 12 months and health-related quality of life at 1 and 12 months will be compared between groups. Postoperative delirium is assessed with the confusion assessment method, falls with ProFaNE consensus questions and quality of life with the Veterans RAND 12-item Health Survey. The intention-to-treat principle will be followed for all analyses. Differences between groups will be presented with 95% CIs and will be considered statistically significant at a two-sided p<0.05. Ethics and dissemination Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES) is approved by the ethics board at Washington University. Recruitment began in January 2015. Dissemination plans include presentations at scientific conferences, scientific publications, internet-based educational materials and mass media. Trial registration number NCT02241655; Pre-results.

Amnesia of the Operating Room in the B-Unaware and BAG-RECALL Clinical Trials.

BACKGROUND:Patient memories of the operating room (OR) may serve as the informational basis for assessing satisfaction with individual anesthesiologists. Furthermore, the provision of clinically important information may assume that perioperative memories are retained. Studies assessing the extent of perioperative amnesia and factors associated with perioperative amnesia are sparse. Therefore, we assessed patient amnesia of the OR and of the preoperative holding area in hospitals where midazolam is typically administered in the preoperative holding area and evaluated whether midazolam dose administered in the preoperative holding area and patient age were associated with amnesia of the OR before induction of anesthesia. METHODS:This was a retrospective study among 7750 adult patients who had general anesthesia and participated in the B-Unaware and Bispectral Index or Anesthetic Gas to Reduce Explicit Recall (BAG-RECALL) clinical trials. The last location the patient remembered before induction of anesthesia and the first location they remembered after induction of anesthesia were determined through a modified Brice questionnaire administered over the phone 30 days postoperatively. Regarding the preoperative period, patients were excluded if their last memory was unclear with respect to location before induction of anesthesia or if they were recruited at Winnipeg, where midazolam was typically first administered in the OR. Midazolam dose (mg/kg) administered in the preoperative holding area was divided into quartiles. Poisson regression models were used to calculate age- and multivariable-adjusted odds ratios (95% confidence intervals [CIs]) for the association between midazolam dose and amnesia of the OR before induction of anesthesia. RESULTS:Of the 5339 patients included, 59.5% (95% CI, 58.2–60.9) of patients had amnesia of the OR before induction of anesthesia. In addition, 44.1% (95% CI, 42.8–45.7) last remembered the preoperative holding area, and 15.4% (95% CI, 14.4–16.4) only had preoperative memories before the holding area. The percentages of patients with amnesia of the OR before induction of anesthesia differed according to age groups: 50.7% (95% CI, 47.7%–53.7%) in patients aged 18 to 47 years versus 70.0% (95% CI, 67.0%–72.9%) in patients aged 73 to 99 years. Patients in the highest midazolam quartile had an adjusted prevalence ratio of 1.31 (95% CI, 1.22–1.42) for amnesia of the OR compared with those who did not receive midazolam. CONCLUSIONS:In hospitals where patients typically receive midazolam in the preoperative holding area, the majority of patients do not remember the OR, and a clinically relevant number of patients does not remember the preoperative holding area. If additional studies produce results indicating that a substantial proportion of patients has amnesia of the anesthesiologist, these findings would argue against the validity of assessing patient satisfaction with individual anesthesiologists providing exclusively OR care in such hospitals. Furthermore, if additional studies yield findings suggesting patient amnesia of the preoperative holding area, these results would suggest reconsideration of providing clinically important information only in the preoperative holding area. Older age and midazolam-induced anterograde amnesia are probably associated with impaired perioperative memories.

Convergent Validity of Three Methods for Measuring Postoperative Complications

Background:Anesthesiologists need tools to accurately track postoperative outcomes. The accuracy of patient report in identifying a wide variety of postoperative complications after diverse surgical procedures has not previously been investigated. Methods:In this cohort study, 1,578 adult surgical patients completed a survey at least 30 days after their procedure asking if they had experienced any of 18 complications while in the hospital after surgery. Patient responses were compared to the results of an automated electronic chart review and (for a random subset of 750 patients) to a manual chart review. Results from automated chart review were also compared to those from manual chart review. Forty-two randomly selected patients were contacted by telephone to explore reasons for discrepancies between patient report and manual chart review. Results:Comparisons between patient report, automated chart review, and manual chart review demonstrated poor-to-moderate positive agreement (range, 0 to 58%) and excellent negative agreement (range, 82 to 100%). Discordance between patient report and manual chart review was frequently explicable by patients reporting events that happened outside the time period of interest. Conclusions:Patient report can provide information about subjective experiences or events that happen after hospital discharge, but often yields different results from chart review for specific in-hospital complications. Effective in-hospital communication with patients and thoughtful survey design may increase the quality of patient-reported complication data.

Intraoperative electroencephalogram suppression at lower volatile anaesthetic concentrations predicts postoperative delirium occurring in the intensive care unit

Background Postoperative delirium is a common complication associated with increased morbidity and mortality. A recently‐reported association between intraoperative electroencephalogram suppression and postoperative delirium might be mediated in some patients by a heightened sensitivity to volatile anaesthetics. Methods This retrospective cohort study included 618 elective surgery patients with planned intensive care unit admission, who also received intraoperative electroencephalogram monitoring and had delirium assessments documented in the medical record. Sensitivity to volatile anaesthetics was assessed using a mixed effects model predicting the likelihood of electroencephalogram suppression at each time point based on the current end‐tidal anaesthetic concentration. Patients with a random intercept above the population median (electroencephalogram suppression at lower anaesthetic concentrations) were classified as having heightened sensitivity to volatile anaesthetics. Delirium was defined as a positive Confusion Assessment Method for the Intensive Care Unit assessment anytime in the first five postoperative days. Results Postoperative delirium was observed in 162 of 618 patients (26%). Patients who experienced electroencephalogram suppression at lower volatile anaesthetic concentrations had a higher incidence of postoperative delirium [109/309 (35%)] than other patients [53/309 (17%)] [unadjusted odds ratio 2.63; 95% confidence interval (CI), 1.81–3.84, P<0.001]. This association remained significant after adjusting for patient characteristics, surgical variables, and duration of electroencephalogram suppression (adjusted odds ratio 2.13; 95% CI 1.24–3.65, P=0.006). Conclusions These data support the hypothesis that patients with electroencephalogram suppression at lower volatile anaesthetic concentrations have an increased incidence of postoperative delirium. Such patients appear to exhibit a phenotype of anaesthetic sensitivity, which might predispose them to adverse cognitive outcomes.

Using machine learning techniques to develop forecasting algorithms for postoperative complications: Protocol for a retrospective study

Introduction Mortality and morbidity following surgery are pressing public health concerns in the USA. Traditional prediction models for postoperative adverse outcomes demonstrate good discrimination at the population level, but the ability to forecast an individual patient’s trajectory in real time remains poor. We propose to apply machine learning techniques to perioperative time-series data to develop algorithms for predicting adverse perioperative outcomes. Methods and analysis This study will include all adult patients who had surgery at our tertiary care hospital over a 4-year period. Patient history, laboratory values, minute-by-minute intraoperative vital signs and medications administered will be extracted from the electronic medical record. Outcomes will include in-hospital mortality, postoperative acute kidney injury and postoperative respiratory failure. Forecasting algorithms for each of these outcomes will be constructed using density-based logistic regression after employing a Nadaraya-Watson kernel density estimator. Time-series variables will be analysed using first and second-order feature extraction, shapelet methods and convolutional neural networks. The algorithms will be validated through measurement of precision and recall. Ethics and dissemination This study has been approved by the Human Research Protection Office at Washington University in St Louis. The successful development of these forecasting algorithms will allow perioperative healthcare clinicians to predict more accurately an individual patient’s risk for specific adverse perioperative outcomes in real time. Knowledge of a patient’s dynamic risk profile may allow clinicians to make targeted changes in the care plan that will alter the patient’s outcome trajectory. This hypothesis will be tested in a future randomised controlled trial.

Study protocol for the Anesthesiology Control Tower—Feedback Alerts to Supplement Treatments (ACTFAST-3) trial: a pilot randomized controlled trial in intraoperative telemedicine

Background: Each year, over 300 million people undergo surgical procedures worldwide. Despite efforts to improve outcomes, postoperative morbidity and mortality are common. Many patients experience complications as a result of either medical error or failure to adhere to established clinical practice guidelines. This protocol describes a clinical trial comparing a telemedicine-based decision support system, the Anesthesiology Control Tower (ACT), with enhanced standard intraoperative care. Methods: This study is a pragmatic, comparative effectiveness trial that will randomize approximately 12,000 adult surgical patients on an operating room (OR) level to a control or to an intervention group. All OR clinicians will have access to decision support software within the OR as a part of enhanced standard intraoperative care. The ACT will monitor patients in both groups and will provide additional support to the clinicians assigned to intervention ORs. Primary outcomes include blood glucose management and temperature management. Secondary outcomes will include surrogate, clinical, and economic outcomes, such as incidence of intraoperative hypotension, postoperative respiratory compromise, acute kidney injury, delirium, and volatile anesthetic utilization. Ethics and dissemination: The ACTFAST-3 study has been approved by the Human Resource Protection Office (HRPO) at Washington University in St. Louis and is registered at clinicaltrials.gov ( NCT02830126). Recruitment for this protocol began in April 2017 and will end in December 2018. Dissemination of the findings of this study will occur via presentations at academic conferences, journal publications, and educational materials.