Schedule the short procedure first to improve OR efficiency

AORN Journal, Oct, 2003 by Philip Lebowitz

Imagine an OR suite in, which the patients on each ORs schedule always are prepared and available for their surgical procedures at the exact time that the preceding procedure ends. In this idealized vision, there is no down time because of late surgeons or patients, and ORs function at a high level of efficiency. Such a back-to-the-future scenario resembles OR suites of the 1960s and earlier, when surgical patients were admitted preoperatively and OR procedures were scheduled "to follow."

To satisfy their customers (ie, surgeons and patients), today's OR managers face a greater OR scheduling challenge than their counterparts encountered in the previous generation. Scheduling surgery "to follow" is impractical because full-service hospitals schedule approximately 70% of surgery as ambulatory or same-day procedures. Staff members instruct patients to come to the hospital at a specific time and to expect a "reasonable" wait as they are readied for their surgery. Surgeons coordinate their activities to reserve a specific block of the day according to the hours that their surgical procedures are scheduled. Consequently, OR scheduling today is time-oriented and time-specific.

DETERMINANTS OF OPTIMAL OR SCHEDULING

Using regression analysis, one study concluded that for any procedure, the surgeon's speed predominates among all variables in determining procedure duration. (1) Consequently, to make the most accurate predictions about procedure start times, many OR managers use computer programs that take historical information about procedure durations for specific combinations of surgeon and procedure to predict each scheduled procedure's duration and to derive accurate start times. Several problems exist with this approach.

First, except for highly specialized facilities (eg, an ophthalmic surgery center), busy hospitals perform such a variety of surgical procedures that obtaining sufficient historical data to derive reliable predictive procedure durations for most surgeon/procedure combinations is impossible. One study's finding uderlines the scope of the problem. In 74% of tertiary surgical suite procedures presented for scheduling at Stanford University Hospital & Clinics, the scheduling program could not reference nine of more previous procedures of the same type performed by the same surgeon during the preceding year. The corresponding number for ambulatory surgery center procedures was 61%. In fact, there were no previous procedures available for comparison in 37% of tertiary surgical suite procedures and 28% of ambulatory surgery center procedures. (2)

Even if OR managers use any surgeon's procedure duration as a surrogate for a specific surgeon's performance of a given procedure, sufficient data on lacking. A study found, for example, that 36% of ambulatory surgical procedures were performed less frequently than once per facility per year. Further, the study's authors estimated that nationally, surgeons schedule al-most 100,000 current procedural terminology (CPT) codes, alone or in combination--far beyond the experience of any one hospital. They concluded that to provide reliable historical data for nearly all procedures, OR managers would need pooled data from millions of procedures. (3)

The second problem involves the inherent variability in procedure durations. Even when reliable historical information is available about a specific surgeon/procedure computerized scheduling systems typically determine the mean value to predict the next procedure's duration. The dispersion of durations around the mean dictates, however, that when procedures are normally distributed, they last either longer or shorter than the mean in roughly equal frequency of occurrence. The greater the number of previous procedures of a given type, the more accurately a computer program can predict the duration of the next procedure of that type. Procedures that last a shorter time than predicted might result hi wasted time unless the patient and surgeon can be mobilized earlier than planned or another procedure can be interposed. Procedures that last longer than predicted cause both the surgeon and patient to wait.

STRATEGIES FOR SUCCESS

For OR managers whose ORs are fully staffed and who want to keep their ORs operating optimally, several strategies are logical outcomes of these research findings. The first strategy, good logistics management, emanates from an OR manager's obligation to prevent shortfalls in personnel or equipment from limiting the rate of flow in OR activity. Good logistics management provides

* adequate overall staffing numbers,

* an appropriate assortment of skills to accommodate the array of scheduled surgical procedures,

* all required equipment and supplies readied in usable condition by the time each procedure has been scheduled,

* procedures scheduled at times that required equipment is available and not being used by another surgeon. (4) If all these logistical needs are met,

OR managers can implement a second strategy--sequencing a series of elective procedures by a given surgeon on a given day so that the time patients have to wait at the surgical suite is minimized. Limiting uncertainty improves on-time performance. Scheduling specific surgeon/procedure combinations for which reliable historical data is lacking can be imprecise, so OR managers can more efficiently meet this goal by sequencing such procedures after commonly performed surgeon/procedure combinations for which good data exist.