Mathematical Modeling To Define Optimum Operating Room Staffing Needs For Trauma Centers - Research Review

AORN Journal,  Feb, 2002  by Victoria Steelman

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MATHEMATICAL MODELING TO DEFINE OPTIMUM OPERATING ROOM STAFFING NEEDS FOR TRAUMA CENTERS C E Lucas et al Journal of the American College of Surgeons Vol 192 (May 2001) 559-565

Staffing the night shift has long been a problem for both perioperative staff nurses and managers. Staff nurses often consider this shift undesirable because it interferes with their personal lives. Managers consider it difficult to find qualified nurses to work this shift. Trauma procedures performed on this shift often are more variable than those performed on the day shift, and staff member leaders are not present to assist with complex decision making. There also may be periods of time when no procedures are being performed, thus nurses are paid for down time. One alternative that may be more cost-effective is to have nurses on call and available in minutes if an emergency arises. Recognizing these financial implications, in 1999, the American College of Surgeons (ACS) committee on trauma redefined the optimal resources needed to provide care to injured patients. Level two trauma centers may be verified by using on-call teams rather than staffing the OR at all times. This change was made with the caveat that a performance improvement process be in place to support the safety of this alternative.

Methodology. Using queuing theories and simulations, researchers at Wayne State University, Detroit, examined the issue of staffing the night shift with a call team versus having that team available in house. Data were collected for 72 designated trauma centers, including 37 level one trauma centers, 28 level two centers, four level three centers, and three pediatric trauma centers. Initial data were collected from the ACS committee on trauma database, including type of center, level of center, and number of admissions. Data regarding the number of patients undergoing surgery and total number of procedures performed between 11 PM and 7 AM were collected during 12 consecutive months. This data includes

* the hour that the procedure began,

* day of week and month of admission,

* time from arrival at the center to the beginning of the procedure,

* type of injury (ie, blunt versus penetrating), and surgical service.

* Researchers developed annual histograms of arrival times and ratios of admissions to procedures performed on the night shift. The possibility that a patient would need surgery within 30 minutes of arrival was calculated and correlated with the annual admission rate and type of injury. Researchers then used a simulation method to determine the probability that there would be two patients requiring surgery at the same time. A mathematical model was used to generate 1,000 simulations so researchers could determine the likelihood that one on-call team would be activated and a second would be needed.

Results. Annual admission rates varied by level of trauma center. Level one trauma centers averaged 1,477 admissions; level two averaged 802; level three averaged 481; and pediatric trauma centers averaged 731. A total of 946 procedures were performed on the night shift, and this number was associated with the number of admissions to each center (P < .001); thus, the higher the number of admissions, the higher the number of procedures performed on the night shift. The types of procedures included general surgery (39%), orthopedic (33%), neurosurgery (8%), another specialty (9%), and multiple services (10%). The time from admission to procedure was within 30 minutes for 12.1% of patients. The probability of a procedure starting within 30 minutes of arrival varied with the number of admissions and the ratio of penetrating versus blunt injuries. The likely number of procedures starting between 11 PM and 7 AM was 19 for 500 annual admissions, 26 for 750 annual admissions, and 34 for 1,000 annual admissions. The probability of two ORs being occupied simultaneously was 0.14 for centers admitting 500 patients and 0.24 for centers admitting 1,000 patients.

Discussion. The researchers conclude that for trauma centers experiencing a high volume of admissions, it is necessary to staff the night shift with more than one OR team. For centers experiencing a low volume of admissions, however, the number of procedures performed on the night shift is low and the probability of running two ORs at the same time is extremely low. The researchers contend that trauma centers with fewer than six procedures on the night shift annually might consider conserving resources by using a call team instead of a second team. They also acknowledge the importance of tracking this practice through a quality management program.

Perioperative Implications. This study is valuable because it addresses a very important perioperative question--when is it appropriate to use a call team rather than a team working the entire shift? With financial pressure on health care organizations and the imminent crisis of fewer perioperative nurses, it is imperative that managers consider alternatives to current practice. One logical alternative is to use a call team. The strength of this study lies in sound mathematical modeling and the inclusion of 72 different trauma centers. This allows the findings to be generalized to trauma centers. As the researchers concluded, using a call team saves labor costs associated with staffing that shift; however, the research itself provides incentive for further research that clearly is needed.