A Retrospective Observational Study of Anesthetic Induction Dosing Practices in Female Elderly Surgical Patients: Are We Overdosing Older Patients?

Background/Objectives: Despite guidelines suggesting a 25–50 % reduction in induction doses of intravenous anesthetic agents in the elderly (≥65 years), we hypothesized that practitioners were not sufficiently correcting drug administration for age, contributing to an increased incidence of hypotension in older patients undergoing general anesthesia. Study Design: We conducted a retrospective, observational study in a tertiary-care academic hospital. The study included 768 female patients undergoing gynecologic surgeries who received propofol-based induction of general anesthesia. Main Outcome Measures: Weight-adjusted anesthetic induction dosing, age-associated differences in dosing by ASA-PS (American Society of Anesthesiology—Physical Status), and hemodynamic outcomes between younger (18–64 years, n = 537) and older (≥65 years, n = 231) female patients were analyzed. Results: Older patients received lower doses of propofol and midazolam than younger patients (propofol: 2.037 ± 0.783 vs 2.322 ± 0.834 mg/kg, p < 0.001; midazolam: 0.013 ± 0.014 vs 0.023 ± 0.042 mg/kg, p < 0.001). However, practitioners still consistently exceeded the FDA recommended dose (1–1.5 mg/kg) of propofol for elderly patients. There was no significant difference in the doses of fentanyl administered between the two age groups (1.343 ± 0.744 vs 1.363 ± 0.763 μg/kg, p = 0.744), and doses of fentanyl in older patients exceeded the recommended dose (0.5–1.0 μg/kg). Corresponding to observed overdosing of induction agents, older patients experienced larger decreases in post-induction blood pressure and were more likely to receive vasopressor therapy. Conclusions: Anesthetic induction doses of fentanyl and propofol were not sufficiently corrected in older patients in accordance with recommendations. Significantly greater frequency of post-induction hypotension occurred amongst older patients. Quality improvement efforts may lead to improved outcomes in this vulnerable population.