Hospitals Reducing Delays – Through Improved Surgical Scheduling
By Maged Dessouky, David Belson and Randolph Hall
Managing length of stay (LOS) is one of the most vexing challenges for any hospital. Though patients do need minimum stays for recovery and monitoring, LOS is sometimes too long because patients are forced to wait for surgeries. As a result, patients suffer and hospitals incur “denied days” – an insurer’s rejection of reimbursement because the stay is not medically necessary.
A research team at the University of Southern California, consisting of the authors and graduate students Pavankumar Murali and Bo Zhang, is addressing the LOS problem at the Los Angeles County General Hospital by targeting surgical scheduling and operations through process modeling, process improvement, optimization and simulation. We focus here on the last two steps: optimization and simulation.
Operating rooms are a scarce resource that must be properly allocated among a set of specialties. Each surgical specialty (cardiac, ortho, neuro, etc.) wants its share of the available time. A common hospital surgery scheduling method is “block scheduling” where operating rooms are assigned weekly among each specialty and then the specialty selects among its patients to fill up its allotted block time. The planned weekly block times are a result of compromises among the competing demands.
A reduction of patient waiting times could be accomplished by accurately balancing the room allocation blocks with amount of demand for surgeries from each specialty. In the past, allocation decisions were the result of many factors. For example, since this is a teaching hospital, each specialty requested sufficient time to provide learning experiences for its medical students.
Surgery demand could be forecast based on the past frequency of surgeries by specialty. The average length of surgeries follows a consistent distribution. The surgeries within each specialty include inpatients who occupy a hospital bed until served, outpatients who are scheduled in advance and “red blanket” emergency patients who must be served immediately by preempting the existing schedule. All three of these subcategories follow a consistent pattern that we could use for allocating blocks.
Based on the demand pattern, we formulated a finite-horizon integer programming (IP) model that determines a weekly operating room allocation template that maximizes patient service. A number of patient type priorities (e.g., emergency over inpatient) and clinical constraints (e.g., minimum number of hours allocated to each specialty) are included in the formulation. The solution from the optimization model is entered into a computer simulation that captures the randomness of the processes (e.g., surgery time, demand, arrival time) and no-show rate of the outpatients) and non-linearties. Our models were created in conjunction with nurses, anesthesiologists and surgeons to assure the relevance of the system to their practice.
Results have been significant. The answers from our approach provide daily plans that reduce patient waiting and assure that the correct surgical team and surgery suite is available when needed.
Maged Dessouky is a professor and David Belson is a senior research associate and lecturer in the Daniel J. Epstein Department of Industrial and Systems Engineering in the Viterbi School of Engineering at the University of Southern California. Randolph Hall is vice provost for research advancement at USC.
An efficient and busy operating room is the economic engine that allows most hospitals to remain financially viable. In addition to sophisticated block scheduling and forecasting models, OR throughput can be dramatically improved by optimizing the many sub processes that impact OR flow.
Patient flow management and communication technology and processes are invaluable in ensuring that the right surgeon, team, equipment and instruments are available as schedules vary. Accurate preference cards ensure that once a surgery has begun, a delay will not occur due to lack of appropriate instruments. Effective instrument management systems ensure accurate instrument tray preparation and effective preventive maintenance. Integrated billing systems minimize nursing time required for administrative activities. Parallel processing strategies allow induction and recovery to occur outside of the OR, thereby significantly reducing the amount of time the room is used for nonoperative activity.
For more information, and a case study outlining an effective operating room transformation project, please visit my website.