Patients undergoing major abdominal surgery received restrictive or liberal intravenous fluids during surgery and up to 24 hours thereafter. The restrictive regimen did not improve disability-free ...survival and resulted in increased acute kidney injury.
Abstract
Background
The relative contributions of intraoperative and postoperative hypotension to perioperative morbidity remain unclear. We determined the association between hypotension and a ...composite of 30-day myocardial infarction and death over three periods: (1) intraoperative, (2) remaining day of surgery, and (3) during the initial four postoperative days.
Methods
This was a substudy of POISE-2, a 10,010-patient factorial-randomized trial of aspirin and clonidine for prevention of myocardial infarction. Clinically important hypotension was defined as systolic blood pressure less than 90 mmHg requiring treatment. Minutes of hypotension was the exposure variable intraoperatively and for the remaining day of surgery, whereas hypotension status was treated as binary variable for postoperative days 1 to 4. We estimated the average relative effect of hypotension across components of the composite using a distinct effect generalized estimating model, adjusting for hypotension during earlier periods.
Results
Among 9,765 patients, 42% experienced hypotension, 590 (6.0%) had an infarction, and 116 (1.2%) died within 30 days of surgery. Intraoperatively, the estimated average relative effect across myocardial infarction and mortality was 1.08 (98.3% CI, 1.03, 1.12; P < 0.001) per 10-min increase in hypotension duration. For the remaining day of surgery, the odds ratio was 1.03 (98.3% CI, 1.01, 1.05; P < 0.001) per 10-min increase in hypotension duration. The average relative effect odds ratio was 2.83 (98.3% CI, 1.26, 6.35; P = 0.002) in patients with hypotension during the subsequent four days of hospitalization.
Conclusions
Clinically important hypotension—a potentially modifiable exposure—was significantly associated with a composite of myocardial infarction and death during each of three perioperative periods, even after adjustment for previous hypotension.
Summary Background Nitrous oxide is commonly used in general anaesthesia but concerns exist that it might increase perioperative cardiovascular risk. We aimed to gather evidence to establish whether ...nitrous oxide affects perioperative cardiovascular risk. Methods We did an international, randomised, assessor-blinded trial in patients aged at least 45 years with known or suspected coronary artery disease having major non-cardiac surgery. Patients were randomly assigned via automated telephone service, stratified by site, to receive a general anaesthetic with or without nitrous oxide. Attending anaesthetists were aware of patients' group assignments, but patients and assessors were not. The primary outcome measure was a composite of death and cardiovascular complications (non-fatal myocardial infarction, stroke, pulmonary embolism, or cardiac arrest) within 30 days of surgery. Our modified intention-to-treat population included all patients randomly assigned to groups and undergoing induction of general anaesthesia for surgery. This trial is registered at ClinicalTrials.gov , number NCT00430989. Findings Of 10 102 eligible patients, we enrolled 7112 patients between May 30, 2008, and Sept 28, 2013. 3543 were assigned to receive nitrous oxide and 3569 were assigned not to receive nitrous oxide. 3483 patients receiving nitrous oxide and 3509 not receiving nitrous oxide were assessed for the primary outcome. The primary outcome occurred in 283 (8%) patients receiving nitrous oxide and in 296 (8%) patients not receiving nitrous oxide (relative risk 0·96, 95% CI 0·83–1·12; p=0·64). Surgical site infection occurred in 321 (9%) patients assigned to nitrous oxide, and in 311 (9%) patients in the no-nitrous oxide group (p=0·61), and severe nausea and vomiting occurred in 506 patients (15%) assigned to nitrous oxide and 378 patients (11%) not assigned to nitrous oxide (p<0·0001). Interpretation Our findings support the safety profile of nitrous oxide use in major non-cardiac surgery. Nitrous oxide did not increase the risk of death and cardiovascular complications or surgical-site infection, the emetogenic effect of nitrous oxide can be controlled with antiemetic prophylaxis, and a desired effect of reduced volatile agent use was shown. Funding Australian National Health and Medical Research Council; Australian and New Zealand College of Anaesthetists; Heart and Stroke Foundation of Quebec, Heart and Stroke Foundation of Ontario, Canada; General Research Fund of the Research Grant Council, Hong Kong Special Administrative Region, China.
When anesthesia is titrated using bispectral index (BIS) monitoring, patients generally receive lower doses of hypnotic drugs. Intraoperative hypotension and organ toxicity might be avoided if lower ...doses of anesthetics are administered, but whether this translates into a reduction in serious morbidity or mortality remains controversial. The B-Aware Trial randomly allocated 2463 patients at high risk of awareness to BIS-guided anesthesia or routine care. We tested the hypothesis that the risks of death, myocardial infarction (MI), and stroke would be lower in patients allocated to BIS-guided management than in those allocated to routine care.
The medical records of all patients who had not died within 30 days of surgery were reviewed. The date and cause of death and occurrence of MI or stroke were recorded. A telephone interview was then conducted with all surviving patients. The primary end point of the study was survival.
The median follow-up time was 4.1 (range: 0-6.5) years. Five hundred forty-eight patients (22.2%) had died since the index surgery, 220 patients (8.9%) had an MI, and 115 patients (4.7%) had a stroke. The risk of death in BIS patients was not significantly different than in routine care patients (hazard ratio = 0.86 95% confidence interval {CI}: 0.72-1.01; P = 0.07). However, propensity score analysis indicated that the hazard ratio for death in patients who recorded BIS values <40 for >5 min compared with other BIS-monitored patients was 1.41 (95% CI: 1.02-1.95; P = 0.039). In addition, the odds ratios for MI in patients who recorded BIS values <40 for >5 min compared with other BIS-monitored patients was 1.94 (95% CI: 1.12-3.35; P = 0.02) and the odds ratio for stroke was 3.23 (95% CI: 1.29-8.07; P = 0.01).
Monitoring with BIS and absence of BIS values <40 for >5 min were associated with improved survival and reduced morbidity in patients enrolled in the B-Aware Trial.
This is the first of 2 articles evaluating cardiac events in patients undergoing noncardiac surgery. In this article, we review the magnitude of the problem, the pathophysiology of these events, ...approaches to risk assessment and communication of risk. The number of patients undergoing noncardiac surgery worldwide is growing, and annually 500,000 to 900,000 of these patients experience perioperative cardiac death, nonfatal myocardial infarction (MI) or nonfatal cardiac arrest. Although the evidence is limited, a substantial proportion of fatal perioperative MIs may not share the same pathophysiology as nonoperative MIs. A clearer understanding of the pathophysiology is needed to direct future research evaluating prophylactic, acute and long-term interventions. Researchers have developed tools to facilitate the estimation of perioperative cardiac risk. Studies suggest that the Lee index is the most accurate generic perioperative cardiac risk index. The limitations of the studies evaluating the ability of noninvasive cardiac tests to predict perioperative cardiac risk reveals considerable uncertainty as to the role of these popular tests. Similarly, there is uncertainty as to the predictive accuracy of the American College of Cardiology/American Heart Association algorithm for cardiac risk assessment. Patients are likely to benefit from improved estimation and communication of cardiac risk because the majority of noncardiac surgeries are elective and accurate risk estimation is important to allow informed patient and physician decision-making.
The long-term consequences of an awareness episode vary. Some patients do not have any long-term disability, whereas others develop psychological problems that may be severe and persistent. In this ...study, we compared the incidence of posttraumatic stress disorder (PTSD) in patients with and without confirmed awareness who were randomized in the B-Aware Trial.
We used a matched cohort design, aiming to follow up the 13 patients with confirmed awareness. Each surviving awareness patient was matched with 4 controls for age, sex, surgery type, date of surgery, and hospital. A face-to-face interview was conducted with each awareness patient and matched controls using the Clinician Administered Posttraumatic Stress Disorder Scale.
Data collection for this study occurred between June 2006 and March 2007, with a median follow-up time of 5.3 yr (range, 4.3-5.7 yr). Six of the 13 confirmed awareness patients had died. Five of the 7 confirmed awareness patients (71%) and 3 of the 25 controls (12%) fulfilled the criteria for PTSD at the time of the interview (adjusted odds ratio = 13.3 95% confidence interval: 1.4-650; P = 0.02). The median onset time of symptoms was 14 days (range, 7-243 days) after surgery, and the median duration of symptoms was 4.7 yr (range, 4.4-5.6 yr).
PTSD was common and persistent in the confirmed awareness patients of the B-Aware Trial. Strategies to prevent awareness in patients under general anesthesia are justified.
Major bleeding in noncardiac surgery is common and associated with serious complications. The antifibrinolytic agent tranexamic acid (TXA) reduces bleeding and may reduce the risk of these ...complications. TXA also may have immunomodulatory effects that could reduce surgical site infection. Clinical trials of TXA in noncardiac surgery have been insufficiently powered to evaluate its efficacy and safety. Therefore, large randomised controlled trials of its use in noncardiac surgery are required. To ensure that future clinical trials are feasible and acceptable, we undertook a survey of Fellows of the Australian and New Zealand College of Anaesthetists (ANZCA). Our aims were to ascertain current patterns of TXA administration and to assess the acceptability of randomising patients to intravenous TXA or placebo. A 12-item survey was electronically mailed to 1001 ANZCA Fellows. Two hundred and eighty nine responses were received and analysed (response rate 29%). Ninety-eight percent of respondents had used intravenous TXA in noncardiac surgery; 67% give TXA routinely for lower limb arthroplasty, with smaller proportions giving TXA for spinal surgery (40%) and other major orthopaedic surgery (28%). Almost half (49%) give TXA routinely for major trauma surgery. Thirty-six percent indicated that they did not give TXA for major vascular, abdominal, pelvic or thoracic surgery. The majority administered TXA as a single, fixed dose. Fifty-seven percent agreed that there is uncertainty about the relative risks and benefits of perioperative TXA in noncardiac surgery and 87% agreed that large definitive trials determining the safety and efficacy of perioperative TXA in noncardiac surgery are required. These results indicate that for ANZCA Fellows the use of TXA in noncardiac surgery is highly variable, that there is uncertainty about the safety and efficacy of TXA, and that a large trial would be acceptable.
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