title: Prolonged surgery increases the likelihood of admission of scheduled ambulatory surgery patients.
abstract: OBJECTIVE
  To identify variables influencing the likelihood of unanticipated admission following scheduled ambulatory surgery.
  
  
  METHODS
  Retrospective case-controlled chart review study.
  
  
  METHODS
  A large academic tertiary care hospital.
  
  
  METHODS
  8,549 ASA physical status I, II, III, and IV patients who underwent scheduled ambulatory surgery in 1991.
  
  
  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 the 167 were surgical (43%), anesthetic (28%), and medical (17%) complications. Odds for admission following long surgery (of at least 60 minutes) were 7.5 times (p < 0.001) greater than following short surgery (under 60 minutes). Among long cases, independent variables influencing admission were: general anesthesia [odds ratio 20.8; 95% confidence interval (CI) 4.4 to 45.6], and monitored anesthesia care or regional anesthesia (combined odds ratio 8.3; 95% CI 1.7 to 40.8). ASA physical status and patient age did not significantly influence admission rate for long cases. For short cases, patients over 65 years (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 (odds ratio 3.1; 95% CI 1.0 to 10.1) independently influenced the likelihood of admission. Type of surgery and gender had no detectable effect on admission.
  
  
  CONCLUSIONS
  Surgery duration of 60 minutes or longer was the most important predictor of unanticipated admission following scheduled ambulatory surgery.
authors.affiliation: Department of Anesthesiology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Mingus
authors.forename: C A
authors.initials: CA
authors.lastname: Bodian
authors.forename: C N
authors.initials: CN
authors.lastname: Bradford
authors.forename: J B
authors.initials: JB
authors.lastname: Eisenkraft
mesh_terms: D000328:Adult; D000556:Ambulatory Surgical Procedures; D000758:Anesthesia / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010343:Patient Admission; D012044:Regression Analysis; D012189:Retrospective Studies; D013997:Time Factors