Factors associated with postanesthesia care unit length of stay in adult patients undergoing elective surgery: A prospective observational cohort study

Postanesthesia care unit (PACU) length of stay (LOS) is a key determinant of perioperative patient flow and resource utilization, yet the factors that prolong it remain incompletely defined. This study aimed to identify perioperative factors associated with PACU LOS in adult patients undergoing elective surgery. This prospective observational cohort study was conducted in a tertiary care hospital over a 6-month period. A total of 409 adult patients who underwent elective surgery under general anesthesia, spinal anesthesia, or peripheral nerve block were included. Demographic characteristics, American Society of Anesthesiologists physical status, anesthetic technique and agents, surgical category and grade, anesthesia duration, PACU vital signs, body temperature, pain scores, postoperative nausea and vomiting, shivering and rescue analgesia were recorded. PACU LOS was defined as the time from PACU admission until a modified Aldrete score of 9 or higher was achieved. Univariate associations were assessed with nonparametric tests, and independent predictors were identified using a gamma generalized linear model with a log link. The median PACU LOS was 45 minutes (interquartile range, 45–50). In univariate analyses, PACU LOS was associated with anesthesia duration ( ρ = 0.158, P = .001), surgical grade ( P = .002), anesthetic technique ( P = .021; shorter stay after peripheral nerve block), pain score at PACU admission ( ρ = 0.110, P = .026), rescue analgesia ( P = .027), and postoperative shivering ( P < .001), but not with demographic characteristics, American Society of Anesthesiologists physical status, anesthetic agents, surgical category, body temperature, or postoperative nausea and vomiting. In the multivariable model, major surgery (vs minor surgery; ratio of means 1.13, 95% confidence interval [CI] 1.03–1.23), anesthesia duration (1.06 per hour, 95% CI 1.04–1.08), and postoperative shivering (1.07, 95% CI 1.03–1.12) were independently associated with longer PACU LOS, whereas the associations of peripheral nerve block and admission pain score did not persist after adjustment. Surgical grade, anesthesia duration, and postoperative shivering were independent predictors of PACU LOS, whereas patient characteristics and the choice of anesthetic agent were not. Although their absolute effects were modest, prevention of postoperative shivering may represent a practical, modifiable target for improving PACU efficiency.