Do Patients With Mental Illness Undergoing Office-Based Sedation Require an Increased Propofol Dosage?

Background: Providers report needing higher sedative doses to achieve adequate sedation in patients with mental illnesses. These claims, however, have not been thoroughly assessed.

Purpose: The purpose of the study was to measure the association between mental illness and the propofol dosage necessary to achieve a satisfactory level of anesthesia.

Study design, setting, sample: The study consisted of a single-center, retrospective cohort consisting of patients treated by oral and maxillofacial surgery at the University of Cincinnati Medical Center in 2020. The study was comprised of subjects 15 or older who were American Society of Anesthesiologists (ASA) classification I or II. Subjects under 15 or ASA III or higher were excluded from the study.

Predictor variable: The predictor variable was the presence or absence of mental illness.

Main outcome variable(s): The primary outcome was the total dose of propofol, measured as the total amount of propofol administered divided by the patient's weight in kilograms divided by the length of the procedure in minutes (mg/kg/min). The secondary outcome was the Richmond Agitation-Sedation Scale (RASS) score achieved during sedation.

Covariates: Sex, race, ethnicity, age, weight, body mass index, ASA score, prior tobacco use, marijuana use, use of adjunct midazolam, fentanyl, and ketamine during the procedure, and type of procedure served as covariates.

Analyses: Test statistics were calculated using the Wilcoxon rank-sum test, Kruskal-Wallis test, Spearman rank correlation test, and χ² test for bivariate analyses. Linear and logistic regression models were used to estimate association while controlling for confounding. P values ≤ .05 were considered statistically significant.

Results: The study sample was 409 subjects (36.92% male, mean age 28.27 ± 12.20 years). In bivariate analysis, mental illness did not show any association with propofol dose (mean dose with mental illness 150.85 ± 143.97 mg/kg/min, mean dose without mental illness 116.54 ± 104.16, P = .08) or RASS score (sufficiently sedated with mental illness 63.38%, sufficiently sedated without mental illness 58.80%, P = .36). After adjusting for all previously mentioned covariates, mental illness was statistically associated with propofol dose (P < .01). Adjusting for covariates, only sex had a statistically significant association with the RASS score (P < .05).

Conclusion and relevance: The findings suggest that a patient's mental illness may influence the amount of sedative required to achieve satisfactory anesthesia.