David B. Glick

Prevention of Intraoperative Awareness in a High-Risk Surgical Population

BACKGROUND Unintended intraoperative awareness, which occurs when general anesthesia is not achieved or maintained, affects up to 1% of patients at high risk for this complication. We tested the hypothesis that a protocol incorporating the electroencephalogram-derived bispectral index (BIS) is superior to a protocol incorporating standard monitoring of end-tidal anesthetic-agent concentration (ETAC) for the prevention of awareness. METHODS We conducted a prospective, randomized, evaluator-blinded trial at three medical centers. We randomly assigned 6041 patients at high risk for awareness to BIS-guided anesthesia (with an audible alert if the BIS value was <40 or >60, on a scale of 0 to 100, with 0 indicating the suppression of detectable brain electrical activity and 100 indicating the awake state) or ETAC-guided anesthesia (with an audible alert if the ETAC was <0.7 or >1.3 minimum alveolar concentration). In addition to audible alerts, the protocols included structured education and checklists. Superiority of the BIS protocol was assessed with the use of a one-sided Fishers exact test. RESULTS A total of 7 of 2861 patients (0.24%) in the BIS group, as compared with 2 of 2852 (0.07%) in the ETAC group, who were interviewed postoperatively had definite intraoperative awareness (a difference of 0.17 percentage points; 95% confidence interval [CI], -0.03 to 0.38; P=0.98). Thus, the superiority of the BIS protocol was not demonstrated. A total of 19 cases of definite or possible intraoperative awareness (0.66%) occurred in the BIS group, as compared with 8 (0.28%) in the ETAC group (a difference of 0.38 percentage points; 95% CI, 0.03 to 0.74; P=0.99), with the superiority of the BIS protocol again not demonstrated. There was no difference between the groups with respect to the amount of anesthesia administered or the rate of major postoperative adverse outcomes. CONCLUSIONS The superiority of the BIS protocol was not established; contrary to expectations, fewer patients in the ETAC group than in the BIS group experienced awareness. (Funded by the Foundation for Anesthesia Education and Research and others; BAG-RECALL ClinicalTrials.gov number, NCT00682825.).

Corneal abrasion in hysterectomy and prostatectomy: role of laparoscopic and robotic assistance.

Background: Radical prostatectomy (RP) is most commonly performed laparoscopically with a robot (robotic-assisted laparoscopic radical prostatectomy, R/PROST). Hysterectomy, which may be open hysterectomy (O/HYST) or laparoscopic hysterectomy (L/HYST), has been increasingly frequently done via robot (R/HYST). Small case series suggest increased corneal abrasions (CAs) with less invasive techniques. Methods: The authors identified RP (166,942), O/HYST (583,298), or L/HYST (216,890) discharges with CA in the Nationwide Inpatient Sample (2000–2011). For 2009–2011, they determined odds ratios (ORs) and 95% confidence intervals (CIs) for CA, in R/PROST, non-R/PROST, L/HYST, O/HYST, and R/HYST. Uni- and multivariate models studied CA risk depending on surgical procedure, age, race, year, chronic illness, and malignancy. Results: In 2000–2011, 0.18% RP, 0.13% L/HYST, and 0.03% O/HYST sustained CA. Compared with 17,554 non-R/PROSTs (34 abrasions, 0.19%) in 2009–2011, OR was not significantly higher in 28,521 R/PROSTs (99, 0.35%; OR 1.508; CI 0.987 to 2.302; P < 0.057). CA significantly increased in L/HYST (70/51,323; 0.136%) versus O/HYST (70/191,199; 0.037%; OR 3.821; CI 2.594 to 5.630; P < 0.0001), further increasing in R/HYST (63/21, 213; 0.297%; OR 6.505; CI 4.323 to 9.788; P < 0.0001). For hysterectomy, risk of CA increased with age (OR 1.020; CI 1.007 to 1.034; P < 0.003) and number of chronic conditions (OR 1.139; CI 1.065 to 1.219; P < 0.0001). CA risk was likewise elevated in R/HYST with number of chronic conditions. Being African American significantly decreased CA risk in R/PROST and in R/HYST or L/HYST. Conclusions: L/HYST increased CA nearly four-fold, and R/HYST approximately 6.5-fold versus O/HYST. Identifiable preoperative factors are associated with either increased risk (age, chronic conditions) or decreased risk (race).

Preoperative Clinic Visits Reduce Operating Room Cancellations and Delays

Background: Anesthesiologist-directed preoperative medicine clinics are used to prepare patients for the administration of anesthesia and surgery. Studies have shown that such a clinic reduces preoperative testing and consults, but few studies have examined the impact of the clinic on the day of surgery. The authors tested whether a visit to an anesthesia preoperative medicine clinic (APMC) would reduce day-of-surgery case cancellations and/or case delays. Methods: The authors conducted a retrospective chart review of all surgical cases during a 6-month period at the University of Chicago Hospitals. Case cancellations and rates of first-start case delay over the 6-month period were cross-referenced with a database of APMC attendees in both the general operating rooms and the same-day surgery suite. The impact of a clinic visit on case cancellation and delay in both sites were analyzed separately. Results: A total of 6,524 eligible cases were included. In the same-day surgery suite, 98 of 1,164 (8.4%) APMC-evaluated patients were cancelled, as compared with 366 of 2,252 (16.2%) in the non-APMC group (P < 0.001). In the general operating rooms, 87 of 1,631 (5.3%) APMC-evaluated patients were cancelled, as compared with 192 of 1,477 (13.0%) patients without a clinic visit (P < 0.001). For both operating areas, APMC patients had a significantly earlier room entry time than patients not evaluated in the APMC. Conclusions: An evaluation in the APMC can significantly impact case cancellations and delays on the day of surgery.

A Novel Classification Instrument for Intraoperative Awareness Events

BACKGROUND: Intraoperative awareness with explicit recall occurs in approximately 1–2 cases per 1000. Given the rarity of the event, a better understanding of awareness and its sequelae will likely require the compilation of data from numerous studies. As such, a standard description and expression of awareness events would be of value. METHODS: We developed a novel classification instrument for intraoperative awareness events: Class 0: no awareness; Class 1: isolated auditory perceptions; Class 2: tactile perceptions (e.g., surgical manipulation or endotracheal tube); Class 3: pain; Class 4: paralysis (e.g., feeling one cannot move, speak, or breathe); and Class 5: paralysis and pain. An additional designation of “D” for distress was also included for patient reports of fear, anxiety, suffocation, sense of doom, sense of impending death, or other explicit descriptions. We reviewed 15 studies of the incidence of awareness that provided specific information about awareness reports. Five anesthesiologists at three institutions who developed the categories independently classified the events. An additional 20 individuals (attending anesthesiologists, anesthesiology residents, nurse anesthetists, medical students, and ancillary staff) not involved in the development of the categories also independently classified the events. Fleisss kappa statistic was used to evaluate inter-observer agreement. RESULTS: One hundred fifty-one cases of intraoperative awareness in adults were identified as valid for analysis. The overall kappa value was 0.851 (0.847–0.856, 95% confidence interval) for the basic Classes 1–5. Including additional designations of emotional distress, the overall kappa value was 0.779 (0.776–0.783, 95% confidence interval). CONCLUSION: We report a novel classification instrument for intraoperative awareness events that has excellent inter-observer agreement and that may facilitate the study of intraoperative awareness.

Increased Risk of Intraoperative Awareness in Patients with a History of Awareness

Background:Patients with a history of intraoperative awareness with explicit recall (AWR) are hypothesized to be at higher risk for AWR than the general surgical population. In this study, the authors assessed whether patients with a history of AWR (1) are actually at higher risk for AWR; (2) receive different anesthetic management; and (3) are relatively resistant to the hypnotic actions of volatile anesthetics. Methods:Patients with a history of AWR and matched controls from three randomized clinical trials investigating prevention of AWR were compared for relative risk of AWR. Anesthetic management was compared with the use of the Hotelling’s T2 statistic. A linear mixed model, including previously identified covariates, assessed the effects of a history of AWR on the relationship between end-tidal anesthetic concentration and bispectral index. Results:The incidence of AWR was 1.7% (4 of 241) in patients with a history of AWR and 0.3% (4 of 1,205) in control patients (relative risk = 5.0; 95% CI, 1.3–19.9). Anesthetic management did not differ between cohorts, but there was a significant effect of a history of AWR on the end-tidal anesthetic concentration versus bispectral index relationship. Conclusions:Surgical patients with a history of AWR are five times more likely to experience AWR than similar patients without a history of AWR. Further consideration should be given to modifying perioperative care and postoperative evaluation of patients with a history of AWR.

Protocol for the BAG-RECALL clinical trial: a prospective, multi-center, randomized, controlled trial to determine whether a bispectral index-guided protocol is superior to an anesthesia gas-guided protocol in reducing intraoperative awareness with explicit recall in high risk surgical patients

BackgroundAwareness with explicit recall of intra-operative events is a rare and distressing complication that may lead to severe psychological symptoms. Candidate depth of anesthesia monitors have been developed, partly with the aim of preventing this complication. Despite conflicting results from clinical trials and the lack of incisive validation, such monitors have enjoyed widespread clinical adoption, in particular the bispectral index. The American Society of Anesthesiologists has called for adequately powered and rigorously designed clinical trials to determine whether the use of such monitors decreases the incidence of awareness in various settings. The aim of this study is to determine with increased precision whether incorporating the bispectral index into a structured general anesthesia protocol decreases the incidence of awareness with explicit recall among a subset of surgical patients at increased risk for awareness and scheduled to receive an inhalation gas-based general anesthetic.Methods/DesignBAG-RECALL is a multi-center, randomized, controlled clinical trial, in which 6,000 patients are being assigned to bispectral index-guided anesthesia (target range, 40 to 60) or end-tidal anesthetic gas-guided anesthesia (target range, 0.7 to 1.3 age-adjusted minimum alveolar concentration). Postoperatively, patients are being assessed for explicit recall at two intervals (0 to 72 hours, and 30 days after extubation). The primary outcome of the trial is awareness with explicit recall. Secondary outcomes include postoperative mortality, psychological symptoms, intensive care and hospital length of stay, average anesthetic gas administration, postoperative pain and nausea and vomiting, duration of stay in the recovery area, intra-operative dreaming, and postoperative delirium.DiscussionThis trial has been designed to complement two other clinical trials: B-Unaware and MACS (ClinicalTrials.gov numbers, NCT00281489 and NCT00689091). With the large patient numbers and complementary rigorous designs, it is envisaged that pre-specified meta-analyses will address some of the outstanding controversies and questions relating to processed electroencephalography monitoring.Trial registrationClinicalTrials.gov Identifier: NCT00682825

The effect of propofol-remifentanil anesthesia on selected seizure quality indices in electroconvulsive therapy

BACKGROUND Use of a short-acting opiate to potentiate anesthetic induction agents has been shown to increase seizure duration in electroconvulsive therapy (ECT), but little is known of the effect of this combination on indices of seizure quality. OBJECTIVE To determine whether anesthetic modality affects commonly provided indices of seizure quality. METHODS Twenty-five subjects were given propofol 2 mg/kg body weight for their first ECT session, at which time seizure threshold was titrated. Subjects thereafter alternated between that anesthetic regimen or propofol 0.5 mg/kg plus remifentanil 1 mcg/kg. Linear mixed models with random subject effect, adjusting for electrode placement, electrical charge, and number of treatments, were fit to estimate effect of anesthesia on seizure duration and several standard seizure quality indices (average seizure energy, time to peak electroencephalography (EEG) power, maximum sustained power, interhemispheric coherence, early and midictal EEG amplitude, and maximum sustained interhemispheric EEG coherence). RESULTS Propofol-remifentanil anesthesia significantly lengthened seizure duration and was associated with longer time to reach maximal EEG power and coherence as well as maximal degree of interhemispheric EEG coherence. No effect was seen on early ictal amplitude or average seizure energy index. CONCLUSIONS Propofol-remifentanil anesthesia prolongs seizure duration and has a significant effect on some, but not all, measures of seizure quality. This effect may be of some benefit in cases where adequate seizures are otherwise difficult to elicit. Varying anesthetic technique may allow more precise investigation of the relationships between and relative impacts of commonly used seizure quality indices on clinical outcomes and ECT-related cognitive side effects.

The relationship between competition and quality in procedural cardiac care.

BACKGROUND:Anesthesiologists are frequently involved in efforts to meet perioperative quality metrics. The degree to which hospitals compete on publicly reported quality measures, however, is unclear. We hypothesized that hospitals in more competitive environments would be more likely to compete on quality and thus perform better on such measures. To test our hypothesis, we studied the relationship between competition and quality in hospitals providing procedural cardiac care and participating in a national quality database. METHODS:For hospitals performing heart valve surgery (HVS) and delivering acute myocardial infarction (AMI) care in the Hospital Compare database, we assessed the degree of intrahospital competition using both geographical radius and federally defined metropolitan statistical area (MSA) to determine the degree of intrahospital competition. For each hospital, we then correlated the degree of competition with quality measure performance, mortality, patient volume, and per-patient Medicare costs for both HVS and AMI. RESULTS:Six hundred fifty-three hospitals met inclusion criteria for HVS and 1898 hospitals for AMI care. We found that for both definitions of competition, hospitals facing greater competition did not demonstrate better quality measure performance for either HVS or AMI. For both diagnoses, competition by number of hospitals correlated positively with cost: partial correlation coefficients = 0.40 (0.42 for MSA) (P < 0.001) for HVS and 0.52 (0.47 for MSA) (P < 0.001) for AMI. CONCLUSIONS:An analysis of the Hospital Compare database found that competition among hospitals correlated overall with increased Medicare costs but did not predict better scores on publicly reported quality metrics. Our results suggest that hospitals do not compete meaningfully on publicly reported quality metrics or costs.

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.

Volitional delay of self-reported outcomes: Insights from a case of intraoperative awareness with explicit recall

Intraoperative awareness with explicit recall (AWR) is a self-reported outcome of interest in clinical practice, quality assurance initiatives, and clinical trials. Combining structured postoperative interviews with a preoperative description of AWR is assumed to ensure prompt patient disclosure. We describe a volitionally delayed reporting of AWR because of the perceived unimportance of nondistressing awareness experiences, despite preoperative education and 2 postoperative interviews. This delay had implications for a major randomized controlled trial on AWR. Volitionally delayed self-reported outcomes may affect statistical comparisons in clinical trials and quality assurance initiatives, and delay the treatment of subsequent sequelae in clinical practice. This limitation should be considered, even when using structured outcome assessment and preoperative education.