Post anaesthesia care unit discharge: a clinical scoring system versus traditional time-based criteria

This prospective cohort analysis compared the efficiency of time-based discharge criteria (Group 1) to a modified clinical scoring system (Group 2), incorporating the assessment of pain and temperature, in the post anaesthesia care unit (PACU). Two consecutive series of patients (n = 292) were assessed following general anaesthesia for various surgical procedures. The time taken for patients to satisfy their respective discharge criteria was recorded as PACU length of stay (LOS). Patient group and other factors that may have influenced PACU-LOS were examined using time-to-event analysis. The raw PACU-LOS was not shown to be different between the two groups (log rank test, P = 0.12). Covariate adjusted estimates were used to compare the two discharge criteria and also to identify other factors influencing PACU-LOS. The Cox regression model was poorly specified and a log-logistic accelerated failure time model was found to be the most parsimonious predictive model. Predictors of decreased PACU-LOS were the treatment group (Group 2 versus Group 1) and the covariate recording anaesthetic airway choice (no endotracheal tube (ETT) versus ETT). Surgical time, as a linear function, intra- and postoperative opioid administration, as well as postoperative antiemetic use were predictors of increased PACU-LOS. Patient age, gender, urgency of surgery, and ASA classification were not predictive of PACU-LOS. Using covariate adjusted estimates, the new PACU discharge criteria, based on the Aldrete's scoring system, was associated with a significantly reduced PACU-LOS in comparison with time-based criteria.