Search

Background: Postoperative delirium is common among older patients and preoperative identification of high-risk patients is widely recommended. The aim of this study was to assess whether preoperative cognitive performance using brief screening tools or regional cerebral oxygen saturation (Scto2) was associated with the development of postoperative delirium in older Portuguese patients undergoing elective surgery., Methods: Prospective observational cohort study where preoperative cognitive screening tools (Mini-Cog, Mini-Mental State Examination, verbal fluency) and Scto2 (INVOS 5100C; Medtronic, Ireland) were assessed in 238 patients ≥65 years old undergoing elective surgery between July 2017 and May 2019 at a tertiary academic center in Portugal. The primary outcome was postoperative delirium detected by the 3D-Confusion Assessment Method. Data were analyzed by univariate analysis and multivariable logistic regression., Results: Delirium was identified in 53 patients (22%); 162 patients (68%) had completed only 4 years of education. On multivariable analysis, probable cognitive impairment tested by the Mini-Cog (odds ratio [OR] = 1.57; 95% confidence interval [CI], 0.70-3.53; corrected P value >.999), by the Mini-Mental State Examination (OR = 2.75; 95% CI, 1.23-6.13; corrected P value = .052), and by the animal verbal fluency test (OR = 1.24; 95% CI, 0.49-3.16; corrected P value >.999) were not significantly associated with the development of postoperative delirium. In contrast, lower preoperative Scto2 (OR = 1.08; 95% CI, 1.02-1.14; corrected P value = .024 for each point decrease in Scto2) was associated with postoperative delirium., Conclusions: We did not find enough evidence to suggest that poor preoperative cognitive performance was significantly associated with the development of postoperative delirium in an older Portuguese surgical population with an overall low level of formal education, but rather that preoperative Scto2 may be helpful in identifying patients at risk for delirium., Competing Interests: Conflicts of Interest: See Disclosures at the end of the article., (Copyright © 2020 International Anesthesia Research Society.)

Background: Preexisting cognitive impairment is emerging as a predictor of poor postoperative outcomes in seniors. We hypothesized that preoperative cognitive screening can be performed in a busy preadmission evaluation center and that cognitive impairment is prevalent in elective geriatric surgical patients., Methods: We approached 311 patients aged 65 years and older presenting for preoperative evaluation before elective surgery in a prospective, observational, single-center study. Forty-eight patients were ineligible, and 63 declined. The remaining 200 were randomly assigned to the Mini-Cog (N =100) or Clock-in-the-Box [CIB; N = 100)] test. Study staff administered the test in a quiet room, and 2 investigators scored the tests independently. Probable cognitive impairment was defined as a Mini-Cog ≤ 2 or a CIB ≤ 5., Results: The age of consenting patients was 73.7 ± 6.4 (mean ± SD) years. There were no significant differences between patients randomly assigned to the Mini-Cog and CIB test in age, weight, gender, education, ASA physical status, or Charlston Index. Overall, 23% of patients met criteria for probable cognitive impairment, and prevalence was virtually identical regardless of the test used; 22% screened with the Mini-Cog and 23% screened with the CIB scored as having probable cognitive impairment (P = 1.0 by χ analysis). Both tests had good interrater reliability (Krippendroff α = 0.86 [0.72-0.93] for Mini-Cog and 1 for CIB)., Conclusions: Preoperative cognitive screening is feasible in most geriatric elective surgical patients and reveals a substantial prevalence of probable cognitive impairment in this population.

Background: Scholarly activity is expected of program directors of Accreditation Council for Graduate Medical Education (ACGME)-accredited residency training programs. Anesthesiology residency programs are cited more often than surgical programs for deficiencies in academic productivity. We hypothesized that this may in part reflect differences in scholarly activity between program directors of anesthesiology and surgical trainings programs. To test the hypothesis, we examined the career track record of current program directors of ACGME-accredited anesthesiology and surgical residency programs at the same institutions using PubMed citations and funding from the National Institutes of Health (NIH) as metrics of scholarly activity., Methods: Between November 1, 2011 and December 31, 2011, we obtained data from publicly available Web sites on program directors at 127 institutions that had ACGME-accredited programs in both anesthesiology and surgery. Information gathered on each individual included year of board certification, year first appointed program director, academic rank, history of NIH grant funding, and number of PubMed citations. We also calculated the h-index for a randomly selected subset of 25 institution-matched program directors., Results: There were no differences between the groups in number of years since board certification (P = 0.42), academic rank (P = 0.38), or years as a program director (P = 0.22). However, program directors in anesthesiology had less prior or current NIH funding (P = 0.002), fewer total and education-related PubMed citations (both P < 0.001), and a lower h-index (P = 0.001) than surgery program directors. Multivariate analysis revealed that the publication rate for anesthesiology program directors was 43% (95% confidence interval, 0.31-0.58) that of the corresponding program directors of surgical residency programs, holding other variables constant., Conclusions: Program directors of anesthesiology residency programs have considerably less scholarly activity in terms of peer-reviewed publications and federal research funding than directors of surgical residency programs. As such, this study provides further evidence for a systemic weakness in the scholarly fabric of academic anesthesiology., Competing Interests: Name: Deborah J. Culley, MD Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript Attestation: Deborah J. Culley has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files Conflicts of Interest: Deborah J. Culley received honoraria from American Board of Anesthesiology Dr. Culley is a Director of the American Board of Anesthesiology and a member of the ACGME Anesthesiology RRC Name: Brenda G. Fahy, MD Contribution: This author helped design the study, conduct the study, and write the manuscript Attestation: Brenda G. Fahy has seen the original study data and approved the final manuscript Conflicts of Interest: Brenda G. Fahy received honoraria from American Board of Anesthesiology Dr. Fahy is a Director of the American Board of Anesthesiology and a member of the ACGME Anesthesiology RRC. Name: Zhongcong Xie, MD, PhD Contribution: This author helped write the manuscript Attestation: Zhongcong Xie has seen the original study data and approved the final manuscript Conflicts of Interest: The author has no conflicts of interest to declare. Name: Robert Lekowski, MD Contribution: This author helped conduct the study and write the manuscript Attestation: Robert Lekowski has seen the original study data and approved the final manuscript Conflicts of Interest: The author has no conflicts of interest to declare. Name: Sascha Buetler, MD, PhD Contribution: This author helped conduct the study and write the manuscript Attestation: Sascha Buetler has seen the original study data and approved the final manuscript Conflicts of Interest: The author has no conflicts of interest to declare. Name: Xiaoxia Liu, MS Contribution: This author helped with statistical support and rewriting of the manuscript Attestation: Xiaoxia Liu has seen the original study data and approved the final manuscript Conflicts of Interest: The author has no conflicts of interest to declare. Name: Neal H. Cohen, MD Contribution: This author helped design the study and write the manuscript Attestation: Neal H. Cohen has seen the original study data and approved the final manuscript Conflicts of Interest: Neal H. Cohen Former Chairman of the ACGME Anesthesiology RRC. Name: Gregory Crosby, MD Contribution: This author helped design the study, analyze the data, and write the manuscript Attestation: Gregory Crosby has seen the original study data, reviewed the analysis of the data, and approved the final manuscript Conflicts of Interest: The author has no conflicts of interest to declare.

In order to review the current status of the potential relationship between anesthesia and Alzheimer's disease, a group of scientists recently met in Philadelphia for a full day of presentations and discussions. This special article represents a consensus view on the possible link between Alzheimer's disease and anesthesia and the steps required to test this more definitively.

Background: We have previously demonstrated that aged rats have persistent impairment of spatial memory after sedation with nitrous oxide or general anesthesia with isoflurane-nitrous oxide. Propofol has different receptor mechanisms of action and a favorable short-term recovery profile, and it has been proposed that propofol is devoid of enduring effects on cognitive performance. No studies have investigated this question in aged subjects, however, so we designed an experiment to examine the long-term effects of propofol anesthesia on spatial working memory., Methods: Eighteen-mo-old rats were randomized to 2 h of 100% oxygen-propofol anesthesia (n=11) or to a control group that breathed 100% oxygen (n=10). Propofol was administered by continuous infusion via a tail vein catheter. Rats breathed spontaneously and rectal temperature was maintained. Mean arterial blood pressure was measured noninvasively and a venous blood gas was obtained just before discontinuation of propofol. After a 2-day recovery, spatial working memory was assessed for 14 days using a 12-arm radial maze. The number of total errors, number of correct choices to first error, and time to complete the maze was recorded and analyzed using a repeated measure analysis of variance (ANOVA), with P<0.05 being considered statistically significant., Results: The average propofol infusion rate was 0.6+/-0.1 mg.kg (-1).min(-1), a rate corresponding to a 50% effective concentration dose in adult rats. Mean arterial blood pressure during anesthesia was 100+/-2 mm Hg and venous blood gases remained in the normal range. There was no difference between the control and previously anesthetized rats on any measure of radial arm maze performance, indicating propofol anesthesia produces no lasting impairment in spatial working memory in aged rats., Conclusions: In aged rats, propofol anesthesia is devoid of the persistent memory effects observed with other general anesthetics in this model. Thus, while it appears that the state of general anesthesia is neither necessary nor sufficient for development of postanesthetic memory impairment, the choice of anesthetics may play a role in late cognitive outcome in the aged.

Background: Nitrous oxide is a commonly used anesthetic that inhibits the activity of methionine synthase, an enzyme involved in methylation reactions and DNA synthesis and repair. This inhibition triggers vacuole formation and degeneration of neurons in areas of the developing and mature brain that are important for spatial memory, raising the possibility that nitrous oxide might have sustained effects on learning., Methods: To test this possibility, we randomized 18-month-old Fischer 344 rats (n = 13 per group) to 4 h of 70% nitrous oxide + 30% oxygen or 70% nitrogen + 30% oxygen (control) and assessed memory using a 12-arm radial maze for 14 days beginning 2 days after nitrous oxide inhalation. In separate, identically treated groups of rats, we measured methionine synthase activity in the cortex and liver at the end of nitrous oxide exposure and 2 days later (n = 3 rats per group per time point) using a standard assay., Results: Liver and cortical methionine synthase was inhibited during nitrous oxide inhalation (6% and 23% of control in liver and cortex, respectively; P < 0.01). Liver enzyme activity remained depressed 2 days later, whereas cortical enzyme activity recovered. There was no difference in error rate between control and nitrous oxide treated rats. However, those exposed to nitrous oxide took more time to complete the maze and made fewer correct choices before first error (P < 0.05)., Conclusions: Sedation with 70% nitrous oxide profoundly, but transiently, reduces the activity of cortical methionine synthase but produces lasting impairment in spatial working memory in aged rats.

A recent clinical study demonstrated that deep anesthesia, as measured by Bispectral index monitoring, was associated with increased 1-yr mortality among middle-aged and elderly surgical patients. We have previously demonstrated impaired cognitive performance in aged rats for weeks after general anesthesia with 1.2% isoflurane-70% nitrous oxide-30% oxygen. However, the effects of 2 h of anesthesia with 1.2% isoflurane-70% nitrous oxide-30% oxygen on rodent life expectancy are unknown and may have confounded our results. Accordingly, we designed this study to determine if general anesthesia alters life expectancy in aged rats. Sixteen 22-mo-old Fischer 344 rats were randomized to anesthesia for 2 h with 1.2% isoflurane-70% nitrous oxide-30% oxygen or a control group that received 30% oxygen (n = 8 per group). Rats recovered in an enriched oxygen environment and then were placed in their home cage under routine conditions. The number of days between anesthesia administration and death were recorded and Kaplan-Meier survival curves generated and compared statistically using the log-rank test and bootstrap method. There was no difference in long-term survival between the control and anesthesia groups. Hence, general anesthesia with 1.2% isoflurane-70% nitrous oxide-30% oxygen does not reduce life expectancy in aged Fischer 344 rats.

We have previously demonstrated that general anesthesia with 1.2% isoflurane-70% nitrous oxide impairs acquisition of a radial arm maze task in both young and aged rats when testing begins 2 days after anesthesia and in aged rats when testing begins 2 wk later. We designed this study to examine whether postanesthesia learning impairment is persistent in young rats. Six-month-old rats were randomized to anesthesia for 2 h with 1.2% isoflurane-70% nitrous oxide, 1.8% isoflurane, or a control group that received 30% oxygen (n = 10 per group). Rats recovered for 2 wk and were then tested daily on a radial arm maze for 14 days. There were no differences between the controls and anesthesia groups in number of correct choices to first error or time to complete the maze. There was no main effect of group in terms of total number of errors (P > 0.05) but the group by day interaction was significant (P < 0.05), reflecting improved performance in the 1.2% isoflurane-70% nitrous oxide group relative to controls during the later days of testing (P < 0.005). Hence, in adult rats, previous general anesthesia is not associated with impaired learning 2 wk later. In fact, previous 1.2% isoflurane-70% nitrous oxide improves maze performance 2 wk later.

Aged rats are impaired on a spatial memory task for at least 24-48 h after isoflurane-nitrous oxide anesthesia. In this study, we tested how long the impairment lasts and investigated the role of nitrous oxide. Eighteen-month-old rats were randomized to anesthesia for 2 h with 1.2% isoflurane with or without 70% nitrous oxide or a control group (30% oxygen). Two weeks later, rats were tested daily for 14 days on a 12-arm radial maze. The number of correct choices to first error, total errors, and time to complete the maze were recorded. Rats anesthetized with 1.2% isoflurane with 70% nitrous oxide made fewer correct choices before first error (P < or = 0.05). Trends toward similar results were noted for error rate and time to complete the maze, but these did not achieve statistical significance. Post hoc analysis comparing all anesthetized rats to controls demonstrated that anesthetized rats made fewer correct choices to first error (P < or = 0.05) and took longer to complete the maze (P

Unlabelled: Studies demonstrate lasting cognitive impairment in elderly persons after anesthesia and surgery. We tested the hypothesis that general anesthesia contributes to this cognitive impairment. Six- and 18-mo-old Fischer 344 rats were trained in a 12-arm radial arm maze and were then randomized to anesthesia for 2 h with 1.2% isoflurane/70% nitrous oxide/30% oxygen or a control treatment consisting of 30% oxygen. Rats recovered for 24 h and then were tested daily on the radial arm maze for 8 wk. Performance of young control rats was stable throughout the experiment. In contrast, aged control rats improved their performance as measured by time to complete the maze but not by error rate. After anesthesia, time to complete the maze did not change in young rats, but error rate decreased (P < 0.05 at 1 and 3 wk), indicating improved performance. In contrast, previously anesthetized aged rats failed to improve with repeated testing and took longer to complete the maze than aged control rats (P < 0.05 at 1 and 3 wk). These data demonstrate that general anesthesia with isoflurane and nitrous oxide improves the memory performance on an established spatial memory task in young rats, but in aged rats it attenuates the improvement in performance that otherwise occurs with repeated testing. Therefore, isoflurane and nitrous oxide anesthesia produces a sustained learning impairment in aged rats., Implications: This study demonstrates that general anesthesia with isoflurane and nitrous oxide improves spatial memory in young rats but impairs it in aged rats for at least 3 wk, indicating that it can influence memory for much longer than previously recognized and may adversely affect memory processes in the aged.