An Analysis of Anesthesia Induction Dosing in Female Older Adults

Abstract

Background/Objectives In the context of an aging surgical population, appropriate anesthetic induction dose adjustments for the older adult remain poorly defined. In the present study, we describe the prevalence of excess induction agent dose in reference to US Food and Drug Administration (FDA) guidance and seek to investigate the possible association of such excess dose with postinduction hypotension and postoperative acute kidney injury (AKI). Study Design A retrospective observational study was conducted in a large tertiary teaching hospital in accordance with our a priori analytic protocol as registered on ClinicalTrials.gov (NCT03699696). For inclusion, patients had to be 65 years or older and to have received general anesthesia with propofol induction for gynecologic oncology surgery between December 1, 2014 and July 8, 2018. Descriptive variables of the patients, machine-captured perioperative vital signs, induction anesthetic, and vasopressor/inotrope administrations were recorded. Main Outcome Measures A total of 541 female patients met inclusion criteria. The mean (standard deviation) age of the cohort was 72.20 (5.93) years. Regarding the primary outcome, 65.43% (354 patients, 95% confidence interval 61.2-69.4) of the cohort received more than the FDA recommended 1-1.5 mg/kg induction dose for patients of advanced age undergoing general anesthesia. Results The percentage of patients receiving doses in excess of the FDA guidance remained substantial across all age groups, but decreased progressively with increasing 5-year age intervals (from 74% among those aged 65-69 years to 44% among those aged > 80 years). Excess propofol dose in the present cohort was not associated with our a priori definition of postinduction hypotension. Regarding AKI, among the 30 patients suffering this outcome, it occurred less often in patients who received higher propofol doses (4.1% [9/217] vs. 15.3% [21/138], p < 0.001), a result that may have been confounded by differential rates of missingness. Conclusions Older adults commonly receive propofol induction doses in excess of the FDA guidance. The immediate hemodynamic effects of these doses on postinduction hypotension were not seen in the present cohort, suggesting that propofol dose adjustments may serve as a marker of physicians' judgments as to the frailty of patients. The relevance of the AKI association is difficult to interpret due to the non-differential missingness of AKI data between the two groups.