Perioperative management and circadian rhythm of surgery time jointly influence delayed PACU discharge in elderly patients after general anesthesia: a case-control study of 1469 cases

To investigate the independent influencing factors for delayed discharge from the post-anesthesia care unit (PACU) in elderly patients undergoing non-cardiac surgery under general anesthesia, encompassing preoperative status, intraoperative management, and innovative circadian rhythm dimensions, to provide references for optimizing perioperative management.

This study adopted a retrospective case-control design. A total of 1469 elderly patients (aged≥60 years) who underwent noncardiac surgery under general anesthesia and were admitted to the PACU for recovery at our department between January 2021 and December 2023 were enrolled. Based on whether the time from PACU admission to achieving a modified Aldrete score≥9 exceeded 120 min, patients were divided into a delayed group (n=709) and a non-delayed group (n=760). Data on demographic characteristics, preoperative comorbidities, American Society of Anesthesiologists (ASA) physical status classification, intraoperative management indicators, postoperative monitoring indicators, PACU admission-related indicators and surgery/PACU admission time rhythm data were collected via the Hospital Inpatient Management System and the Anesthesia Clinical Information System. Univariate comparisons of various indicators between the 2 groups were performed using the Chi-square test or binary logistic regression. Subsequently, variables with P<0.05 in the univariate analysis were included in a binary logistic stepwise regression model to analyze the independent factors influencing delayed PACU discharge.

Univariate analysis showed that the delayed group had significantly higher rates of male sex, ASA class Ⅲ-Ⅳ, preoperative respiratory disease, intraoperative use of vasoactive drugs and colloids, total intraoperative fluid intake and output, intraoperative blood loss, postoperative use of intravenous and nerve block analgesia, surgery and anesthesia duration, and body temperature upon PACU admission compared to the non-delayed group (P<0.05). Conversely, the delayed group had a significantly lower rate of using the neuromuscular reversal agent neostigmine and lower postoperative hemoglobin levels (P<0.05). Regarding circadian rhythm, significant differences were found between the 2 groups in the distribution of surgery start time and PACU admission time (P<0.001). Multivariate analysis revealed that preoperative respiratory disease (β =0.616, P<0.001), ASA class Ⅲ-Ⅳ (β =0.501, P=0.002), intraoperative colloid use (β =0.626, P<0.001), increased total intraoperative fluid intake (β=0.001, P<0.001), surgery initiation during the Si period (9:00-11:00) (β=0.353, P=0.005), and PACU admission during the Shen period (15:00-17:00) (β=0.660, P<0.001) were independent risk factors for delayed discharge. In contrast, the use of the neuromuscular reversal agent neostigmine (β =-0.327, P=0.007) and PACU admission during the Xu period (19:00-21:00) (β=-0.468, P=0.042) were independent protective factors.

Delayed discharge from the PACU after general anesthesia in elderly patients is jointly influenced by multiple factors, including preoperative patient status, intraoperative management, recovery-phase interventions, and surgical timing rhythm. Implementing individualized anesthesia and fluid management for high-risk elderly patients, using neuromuscular reversal agents, and considering the time rhythm effects in surgical scheduling and PACU resource allocation may reduce the incidence of delayed PACU discharge after general anesthesia.