Propofol Use in the Elderly Population: Prevalence of Overdose and Association With 30-Day Mortality

Abstract

Purpose: Geriatric patients are more sensitive to the anesthetic effects of propofol and its adverse effects, such as hypotension, than is the general population; thus, a reduced dose (1-1.5 mg/kg) is recommended for the induction of anesthesia. The extent to which clinicians follow established dosing guidelines has not been well described. Therefore, we investigated the prevalence of propofol overdose in the elderly population to determine whether propofol overdose occurs and is associated with increased hypotension and 30-day mortality.

Methods: In this retrospective study in patients who received propofol for the induction of general anesthesia, data on demographic characteristics, preoperative medications, intraoperative management, and 30-day mortality were collected. The dose of propofol used for the induction of anesthesia and the median blood pressure in the pre- and immediate postinduction periods were determined. Hypotension was defined as either: (1) a decrease in mean arterial pressure (MAP) of >40% concurrent with a MAP of <70 mm Hg; or (2) a MAP of <60 mm Hg.

Findings: A total of 17,540 patients were included in the analysis; 4033 (23.0%) were aged >65 years. The median (interquartile range) propofol dose in the group aged >65 years was 1.8 (1.4-2.2) mg/kg, above the recommended dose, in comparison to 2.2 (1.9-2.5) mg/kg in younger patients. On multivariate analysis, increased propofol dose was associated with increased postinduction hypotension, especially in patients over 70 years of age, but not 30-day mortality.

Implications: Older patients received greater-than-recommended doses of propofol for induction, which may have led to significant dose-dependent hypotension. Despite this finding, the dose of propofol for induction was not independently associated with a greater 30-day mortality rate. More education regarding geriatric concerns is needed for encouraging anesthesiologists to tailor the plan for anesthesia in geriatric patients. However, overall postsurgical mortality is a function of preoperative risk and type surgical procedure.

Keywords: 30-day mortality; elderly; hypotension; propofol overdose.

Figure 1

Scatterplot showing the relationship between age and propofol-induction dose (mg/kg). Dose of propofol decreases as age increases, but not as much as published guidelines would recommend. The dark line is a smoothed curve generated using the penalized B-spline method (PROC SGCATTER, SAS; SAS Institute Inc, Cary, North Carolina).

Figure 2

Odds ratios (95% CI) of postinduction hypotension per increase in dose of propofol used for induction (mg/kg), stratified by decade over 60 years of age. The steeper slopes seen in older age groups suggest that these groups are more susceptible than are younger groups to hypotension with greater doses of propofol.