Preoperative respiratory functional patterns and time to hospital discharge

Introduction: Preoperative respiratory functional patterns may influence in-hospital outcomes beyond respiratory complications. Objective: To analyze the association between preoperative respiratory functional patterns and time to hospital discharge in patients undergoing non-cardiac surgery. Method: This was a secondary analytical study including 6,245 patients undergoing non-cardiac surgery under general anesthesia. Preoperative respiratory classification was analyzed as normal, obstructive, or spirometric pattern compatible with restriction, the latter not implying confirmed true pulmonary restriction. The outcome was time to hospital discharge, expressed in days. The association was evaluated using accelerated failure time models with a log-normal distribution, reporting time ratios adjusted for age, sex, BMI, ASA classification, and emergency surgery. An extended model including surgical variables and sensitivity analyses using discharge time in hours and length of stay winsorized at the 99th percentile was performed as robustness assessments. Results: The obstructive respiratory pattern showed no difference in time to discharge compared with the normal pattern. The spirometric pattern compatible with restriction was associated with a significant prolongation of hospitalization (TR: 1.27; 95% CI: 1.16-1.39). In the extended model adjusted for surgical variables, this association remained consistent (TR: 1.23; 95% CI: 1.16-1.32). Older age, male sex, higher ASA classification, and emergency surgery were associated with longer length of stay. Conclusions: Preoperative respiratory functional classification, particularly the spirometric pattern compatible with restriction, may provide useful information for anticipating in-hospital outcomes in non-cardiac surgery.