Room Utilization

The scarcest resources in a surgery center are the operating rooms themselves. Surgeons are always itching to operate, patients want their elective cases done, and you can hire more anesthesiologists and nurses. But rooms are a fixed resource. That's why room utilization is such an important concept in operating room management. After you determine how long each room is going to be open for, you have to fill those rooms with cases. If those cases finish early, the room is under-utilized, and staff expecting to work will have nothing to do. If those cases finish late, the room is over-utilized, and you have to pay overtime and deal with staff morale. So the optimal utilization of rooms is a big deal.

Predicting utilization is really, really hard. Different specialties and different cases have varying levels of predictability. For example, a seasoned cataract surgeon can probably get her utilization optimized fairly easily. A general surgeon who only does large bowel resections will have trouble. Not only are bigger cases more variable in their timing, but they are also harder to slot into block time. That is, if a general surgeon is allocated 8 hours of block time in an operating room but has a 6 hour case, if he does not find a 2 hour case, he will under-utilize the room.

Predictability is important as well. A surgeon may vary on how long he takes to do a specific operation, and different surgeons will vary on how long they take to do that operation. Furthermore, this distribution of case duration is not a normal distribution on a bell curve; rather, most cases will cluster together but the average duration will be pulled up by a few outliers of very difficult or complicated surgeries (such as laparoscopic procedures that have to open). Other problems with this view of OR management is that utilization doesn't necessarily correlate with revenue; a cardiac surgeon may underutilize his block time but make a lot of money for the hospital; utilization shouldn't be a surrogate for optimization of profit.

The problem with utilization is that in order to optimize it, we might want to take away block time from a surgeon who is underutilizing his room and give it to a surgeon who is overutilizing it. This might encourage slow surgeons to remain slow, hoping to get more time, and fast surgeons to slow down, afraid they will lose their time. They may also alter their predictions of case durations; by predicting that they will be faster, they can book more cases. Optimizing utilization means we have to have the data to predict how long a case will take; however, there are thousands of different surgeries, and unless a particular procedure is done frequently (like cataracts or cystoscopy), there will be a lot of unknowns with infrequent surgeries.

All of these variables come into play in real life operating room management, and my two weeks as the ambulatory surgery scheduler gave me a glimpse into this strange world. In medicine, everything revolves around the patient, but in management, everything revolves around efficiency and money.