Introduction: Efficient operating room time use is important in modern medicine, as delays in patient arrival, anesthesia induction, surgical positioning, and recovery in the operating room all increase OR time not spent operating. In this study we sought to determine what factors increase anesthetized, non-operative time, and how significantly by utilizing a database of over 5,000 consecutive neurosurgical spine cases at our institution.

Methods: Surgical records were searched in a retrospective fashion to identify all spine surgeries performed between January 2010 and July 2012. Anesthetized, non-operative time was calculated from the anesthesia record, and was compared to both patient and procedure characteristics to determine any significant relationships

Results: There were 5515 surgical cases with a mean age of 60.5, mean BMI of 29.7 and 3226 (58%) were male. There were 1176 (21%) fusion cases, and level of pathology was predominantly lumbar (4010 cases, 73%). Fusion cases had a significantly longer total anesthetized, non-operative time when compared to non-fusion cases (Fusion – 98 minutes vs. Non-fusion – 76 minutes, mean difference – 22 minutes, p<0.0001). Significant factors affecting anesthetized, non-operative time in non-fusion cases include age greater than 65 (mean difference – 5 minutes, p<0.0001), ASA grade, and BMI (<25 – 72 +/- 1.2 minutes vs. 25-29 - 74 +/- 0.6 minutes vs. 30-39 - 79 +/- 0.6 minutes vs. 40+ - 87 +/- 1.8 minutes, p<0.0001). Age, ASA grade and BMI all maintained significance on multivariate analysis. Similarly, for fusion operations, age >65 was significantly associated with increased non-operative time (mean difference – 6 minutes, p<0.01), increasing ASA (mean difference 9 minutes, p<0.0001) and increasing BMI. Age, ASA grade and BMI all maintained significance on multivariate analysis.

Conclusions: Patient and surgical factors, such as age, ASA grade, BMI, level of pathology and surgical approach have noticeable effects on anesthetized, non-operative times in spine surgery.

Patient Care: This research will improve patient care by identifying areas for improvement in operating room time utlilization and identifying patient/procedure specific factors that influence non-operative time. This could lead to interventions whereby specific patients are listed as "high efficiency" patients, receiving complex access and monitoring in the pre-operative area rather than waiting to perform all of these procedures after anesthetic induction

Learning Objectives: By the conclusion of this session, participants should be able to 1) Identify patient specific factors that increase anesthetized, non-operative time in spine surgery, 2) Identify procedure specific factors that increase this time and 3) Identify areas for improvement and incrased efficiency within the OR patient flow

References: 1. Babineau TJ, Becker J, Gibbons G, Sentovich S, Hess D, Robertson S, et al: The "cost" of operative training for surgical residents. Archives of surgery 139:366-369; discussion 369-370, 2004 2. Bridges M, Diamond DL: The financial impact of teaching surgical residents in the operating room. American journal of surgery 177:28-32, 1999 3. Davis EA, Escobar A, Ehrenwerth J, Watrous GA, Fisch GS, Kain ZN, et al: Resident teaching versus the operating room schedule: an independent observer-based study of 1558 cases. Anesthesia and analgesia 103:932-937, 2006 4. Delaney CL, Davis N, Tamblyn P: Audit of the utilization of time in an orthopaedic trauma theatre. ANZ journal of surgery 80:217-222, 2010 5. Eappen S, Flanagan H, Bhattacharyya N: Introduction of anesthesia resident trainees to the operating room does not lead to changes in anesthesia-controlled times for efficiency measures. Anesthesiology 101:1210-1214, 2004 6. Kauvar DS, Braswell A, Brown BD, Harnisch M: Influence of resident and attending surgeon seniority on operative performance in laparoscopic cholecystectomy. The Journal of surgical research 132:159-163, 2006 7. Koenig T, Neumann C, Ocker T, Kramer S, Spies C, Schuster M: Estimating the time needed for induction of anaesthesia and its importance in balancing anaesthetists' and surgeons' waiting times around the start of surgery. Anaesthesia 66:556-562, 2011 8. Kougias P, Tiwari V, Barshes NR, Bechara CF, Lowery B, Pisimisis G, et al: Modeling anesthetic times. Predictors and implications for short-term outcomes. The Journal of surgical research 180:1-7, 2013 9. Schuster M, Kotjan T, Fiege M, Goetz AE: Influence of resident training on anaesthesia induction times. British journal of anaesthesia 101:640-647, 2008 10. Schuster M, Standl T, Wagner JA, Berger J, Reimann H, Am Esch JS: Effect of different cost drivers on cost per anesthesia minute in different anesthesia subspecialties. Anesthesiology 101:1435-1443, 2004 11. Shabtai M, Rosin D, Zmora O, Munz Y, Scarlat A, Shabtai EL, et al: The impact of a resident's seniority on operative time and length of hospital stay for laparoscopic appendectomy: outcomes used to measure the resident's laparoscopic skills. Surgical endoscopy 18:1328-1330, 2004 12. Tyler DC, Pasquariello CA, Chen CH: Determining optimum operating room utilization. Anesthesia and analgesia 96:1114-1121, table of contents, 2003 13. Wang WN, Melkonian MG, Marshall R, Haluck RS: Postgraduate year does not influence operating time in laparoscopic cholecystectomy. The Journal of surgical research 101:1-3, 2001