Improving operating room (OR) efficiency has become a high priority for many surgical units. Managing, planning, organizing, leading and controlling are distinct, interrelated and simultaneous functions of management essential for the smooth running of an OR complex. Management of the OR is intricate because of the variety of procedures and clinical perception of patients, the diverse nature of the staff, as well as the interaction between people and processes in other parts of the hospital. Probably the most troublesome problem in the OR concerns the scheduling of cases [1,2]. Surgeons have office duties and operate electively as well as dealing with emergency cases; thus, they would much prefer to work to a predictable OR schedule. Both anaesthetists and surgeons need time to visit and evaluate their patients for the following day. Therefore, both specialities have a vested interest in finishing their duties in the OR before other hospital services become unavailable (e.g. clinical laboratories, radiology and organ function test units).
The following deficiencies were the reason for conducting the study in five ORs of the Clinic for Gynaecology at the University Hospital, Zurich, Switzerland. First, the surgical programme regularly lasted until quite late in the afternoon such that the attending gynaecologists could not resume their work afterwards in the ward on time. Second, the turnaround time between any two sequential operations was considered as unduly long because there were insufficient anaesthesia staff available to perform any overlapping induction of anaesthesia. 'Overlapping' in this context relates to commencing the induction of anaesthesia of a patient before the preceding case has finished. Third, it was not always possible to conform to the regulations for the agreed working time of staff. It was assumed that by increasing the existing complement of the anaesthesia team - of two senior anaesthetists, two residents and three anaesthesia nurses - by one additional physician and one nurse, the efficiency in the OR would be improved because overlapping induction of anaesthesia could be undertaken [3,4]. To test this hypothesis, a multidisciplinary team collected procedural times and subsequently measured the impact of this approach. The aim was to investigate the change in the overall efficiency of the OR in terms of financial benefits and the decrease of time spent in the OR by physicians and nurses at a university hospital.
The study was conducted at the Department of Gynaecology of the University Hospital Zurich, Switzerland, which is a tertiary referral centre. The investigation was designed as a prospective, non-randomized, interrupted time-series analysis in three distinct observational periods: (a) a baseline over 3.5 months, (b) a 2.5 month intervention phase in which anaesthesia staffing was increased by one attending physician and one nurse and (c) a subsequent 2 months under baseline conditions again. A specifically designed data set was collected from OR staff, anaesthesia personnel and surgeons using a structured questionnaire designed in the commercially available Teleform® computer program (SPSS v.10.0®; SPSS Inc., Chicago, IL, USA). The time intervals assessed were defined as: operation time, i.e. the time from skin incision to the last surgical stitch; anaesthesia time, i.e. the time from induction of anaesthesia to tracheal extubation; turnover time, i.e. the time from the moment the patient leaves the OR until the next patient enters it (this time was documented between subsequent cases); and cumulative occupancy of the OR, i.e. the time from the moment when the first patient enters to when the last patient in the session leaves the OR.
All gynaecological surgery, which occurred during the regular OR working time from 7:00 a.m. to 4:00 p.m., Monday to Friday, was included. A response rate of 96% was achieved by ensuring that the questionnaires from all participants were completed on a daily basis and transferred immediately to the analysing centre. Although no formal validation analysis was conducted, the information from the data sets was double-checked and was of good quality.
Cost data were calculated for the five most frequent kinds of operation from the database. They were obtained by taking a relative value-based hospital tariff code for physician and nursing services provided by the hospital administration. OR costs were assessed based on charge surrogates, originating from the financial accounting system of the hospital. Efficiency was defined as the number of operative procedures per unit time.
Data were presented for continuous variables as the mean and confidence intervals (CI). Assessment of univariate associations were performed as follows: Pearson's correlation coefficients were calculated for continuous independent variables; a t-test and ANOVA were used for categorical independent variables. P ≤ 0.05 was taken as the level of two-tailed significance.
During the observational period of 8 months, timing data were collected from 1282 operations, divided over the three periods. The following variables were influenced by the intervention and changed significantly: mean turnover time decreased by 13 min (95% CI: 9; 17) or from 65 to 53 min per operation (P = 0.0001). Using a conservative estimate of two cases per OR per day, 26 min day−1, were saved in each OR during the intervention period. Moreover, occupancy in the OR was increased by 59 min (95% CI: 50; 68) or from 4:28 to 5:27 h day−1 (P = 0.005). Thirty additional operations could be performed during the intervention period of 2.5 months compared with the baseline period; this represents an increase of 43%, but the number returned to baseline in the third phase. The surgeons began their work in the ward 35 min (95% CI: 30; 40) later than previously and under the final baseline conditions. Their total overtime increased from 22:36 to 139:50 h during the intervention period.
The most frequent operations were: termination of pregnancy, abdominal hysterectomy, hysteroscopy, mastectomy and biopsy excisions of the breast (Table 1). The costs for these operations separate patients with basic insurance from those who had supplemental insurance (Table 2). During the intervention period, the hospital charges for the most frequent gynaecological operations showed a profit that exceeded the expenditure for the additional anaesthesia personnel (Table 3).
The most important finding was that during the intervention period, the efficiency of the OR activity, defined as operations per unit time, increased considerably. This was reflected by 42% more operations being performed and a steep increase in income of €178 200 - an increase of 63%. The main determinant of this change is the number of operations performed due to shortening of the turnover time and intensified scheduling of the OR programme.
Although previous studies have defined OR procedural times , examined OR utilization and efficiency [4,6-8], or examined OR scheduling methodology to optimize efficiency [2,9,10], no prospective data were available that evaluated the impact of an increase in anaesthesia staffing. Turnover time decreased in the study because overlapping anaesthesia induction using a separate induction room was undertaken. However, this only became possible by augmenting the anaesthesia team with one physician and one nurse during the intervention period. Melnik and colleagues  reported that the interval between cases varied between anaesthesiologists and implied that improving efficiency in the OR (i.e. avoiding late starts, motivating slow turnover anaesthesiologists, etc.) might lead to an overall reduction in costs. Reducing non-productive (i.e. non-patient care) time should result in increased efficiency in the OR, thus permitting the generalization of our findings to all ORs.
The additional expenditure incurred to employ these two extra staff members was far outweighed by the financial benefits that resulted. Since we realized that a shorter turnover time meant that more operations could be scheduled, the overall result was an increase in OR efficiency; however, this was offset by a later start for work in the clinical ward. Dexter and colleagues acknowledged that operating units that could accommodate more frequent turnovers per day produced savings and allowed more cases to be scheduled with regularity . Moreover, the increased number of operations performed generated more work in the clinic, so resulting in more overtime for all clinical participants. This state of affairs shows strikingly that the exploitation of a benefit, i.e. increased OR efficiency, must be clearly defined - whether it should be directed towards more income or more time for non-OR activities of those involved.
Because the data from the study were based on self-declaration (by the involved personnel), there is a risk of bias. Unfortunately, the available budget was insufficient to assign external observers, as has been recommended . Owing to the fact that reliable data on the real costs for each patient were difficult to determine, an alternative - of hospital charges - was used instead: this has also been the case in other studies on this subject [12,13]. Significant improvements in OR efficiency can be achieved, not only by an increase in staff, but also by better organization of the flow of work that is presented. Therefore, the multidisciplinary efforts of surgeons, anaesthesiologists and nurses, supervised and integrated by an OR manager, are necessary.
1. Hamilton DM, Breslawski S. Operating room scheduling. Factors to consider. AORN Journal
2. Zhou J, Dexter F. Method to assist in the scheduling of add-on surgical cases - upper prediction bounds for surgical case durations based on the log-normal distribution. Anesthesiology
3. Melnik H, Tessler MJ, Wahba RM. Anesthesiologists and the time interval between cases in cardiac surgery
. J Clin Anesth
4. Mazzei WJ. Operating room start times and turnover times in a university hospital. J Clin Anesth
5. Donham R, Mazzei W, Jones R. Glossary of times used for scheduling and monitoring of diagnostic and therapeutic procedures. Am J Anesth
6. Kanich DG, Byrd JR. How to increase efficiency in the operating room. Surg Clin North Am
7. Cantwell R, Mirza N, Short T. Continuous quality improvement efforts increase operating room efficiency. J Healthe Qual
8. Miliczki-Weimer D. A method of evaluating efficiency in the operating room. J Am Assoc Nurse Anesth
9. Dexter F, Macario A, Lubarsky DA, Burns DD. Statistical method to evaluate management strategies to decrease variability in operating room utilization: application of linear statistical modelling and Monte Carlo simulation to operating room management. Anesthesiology
10. Strum DP, Vargas LG, May JH. Surgical subspecialty block utilization and capacity planning: a minimal cost analysis model. Anesthesiology
11. Overdyk FJ, Harvey SC, Fishman RL, Shippey FSO. Successful strategies for improving operating room efficiency at academic institutions. Anesth Analg
12. Smith LR, Milano CA, Molter BS, et al.
Preoperative determinants of postoperative costs associated with coronary artery bypass graft surgery
13. Denton TA, Luevanos J, Matloff JM. Clinical and nonclinical predictors of the cost of coronary bypass surgery
: potential effects on health care delivery and reimbursement. Arch Int Med