Cumulative duration of "triple low" state of low blood pressure, low bispectral index, and low minimum alveolar concentration of volatile anesthesia is not associated with increased mortality

Abstract

BACKGROUND: Mortality after noncardiac surgery has been associated with the "triple low state," a combination of low mean arterial blood pressure (<75 mmHg), low bispectral index (<45), and low minimum alveolar concentration of volatile anesthesia (<0.70). The authors set out to determine whether duration of a triple low state and aggregate risk associated with individual diagnostic and procedure codes are independently associated with perioperative and intermediate-term mortality. METHODS: The authors studied 16,263 patients (53 ± 16 yr) who underwent noncardiac surgery at Duke University Medical Center between January 2006 and December 2009. Multivariable logistic and Cox regression analyses were used to determine whether perioperative factors were independently associated with perioperative and intermediate-term all-cause mortality. RESULTS: The 30-day mortality rate was 0.8%. There were statistically significant associations between 30-day mortality and various perioperative risk factors including age, American Society of Anesthesiologists Physical Status, emergency surgery, higher Cleveland Clinic Risk Index score, and year of surgery. Cumulative duration of triple low state was not associated with 30-day mortality (multivariable odds ratio, 0.99; 95% CI, 0.92 to 1.07). The clinical risk factors for 30-day mortality remained predictors of intermediate-term mortality, whereas cumulative duration of triple low was not associated with intermediate-term mortality (multivariable hazard ratio, 0.98; 95% CI, 0.97 to 1.01). The multivariable logistic regression (c-index = 0.932) and Cox regression (c-index = 0.860) models showed excellent discriminative abilities. CONCLUSION: The authors found no association between cumulative duration of triple low state and perioperative or intermediate-term mortality in noncardiac surgery patients. Copyright © 2014, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins.