When comparing on-time starts between institutions, it is important to note that “start time” is often defined differently. Wheels-in time, prep/position time, and incision time each have been used as the defining event for a start time. However, a standard definition must be used for comparative metrics. Historically, the standard has been wheels-in time. However, this does not align with the primary purpose of an OR or capture periods of costly delays that often occur after the patient crosses the OR threshold. Incision time includes variables such as prep and positioning that are often difficult to account for in planning for a standard start time. Prep/position time is the time that all components of the OR converge: anesthesiology has completed induction, OR nursing is prepared, and the surgical team is ready. For this reason, prep/position time sets timing expectations for each component of the OR team.

OR efficiency relates to how well OR resources are utilized in completing the actual caseload and can be translated to costs using simple formulae. Underutilized time is the amount of allocated time not used to perform OR workload, while over-utilized time exists when OR workload exceeds allocated time, resulting in overtime or other premium costs. Over-utilized time costs between 1.5 and 2 times underutilized time. Therefore, a goal for the OR manager must be to reduce over-utilized time. The cost of these inefficiencies can be calculated as follows:

An effective OR manager has the authority to manage these inefficiencies by shifting caseload into gaps that develop in the schedule. This idle time often represents the bulk of inefficiency in the OR with attempts to managed this time difficult due to conflict with surgeons from changes in anticipated surgical start times. However, in an environment of limited OR personnel resources, shifting caseload to reduce idle time can reduce over-utilized time and reduce the queues that can develop with restriction of resources later in the day.