PROLONGED SURGERY INCREASES THE LIKELIHOOD OF ADMISSION OF SCHEDULED AMBULATORY SURGERY PATIENTS

Study Objective: To identify variables influencing the likelihood of u nanticipated admission following scheduled ambulatory surgery. Design: Retrospective case-controlled chart review study. Setting: A large ac ademic tertiary care hospital. Patients: 8,549 ASA physical status I, II, III, and IV patients who underwent scheduled ambulatory surgery in 1991. Measurements and Main Results: Of the 8,549 patients, 216 were admitted with complete medical record information available for 167 of the admitted patients. The most common reasons for admission among th e 167 were surgical (43%) anesthetic (28%), and medical (17%) complica tions. Odds for admission following long surgery (of at least 60 minut es) were 7.5 times (p < 0.001) greater than following short surgery (u nder 60 minutes). Among long cases, independent variables influencing admission were: general anesthesia [odds ratio 20.8; 95% confidence in terval (CI) 4.4 to 45.6], and monitored anesthesia care or regional an esthesia (combined odds ratio 8.3; 95% CI 1.7 to 40.8). ASA physical s tatus and patient age did not significantly influence admission rate f or long cases. For short cases, patients over 65 gears (odds ratio 5.6 ; 95% CI 2.6 to 12.0), ASA physical status III or IV (odds ratio 4.8; 95% CI 2.0 to 11.6), use of general anesthesia (odds ratio 4.7; 95% CI 1.5 to 14.2), and monitored anesthesia care or regional anesthesia (o dds ratio 3.1; 95% CI 1.0 to 10.1) independently influenced the likeli hood of admission. Type of surgery and gender had no detectable effect on admission. Conclusions: Surgery duration of 60 minutes or longer r uns the most important predictor of unanticipated admission following scheduled ambulatory surgery. (C) 1997 by Elsevier Science Inc.