A model for understanding the impacts of demand and capacity on waiting time to enter a congested recovery room.
BACKGROUND
When a recovery room is fully occupied, patients frequently wait in the operating room after emerging from anesthesia. The frequency and duration of such delays depend on operating room case volume, average recovery time, and recovery room capacity.


METHODS
The authors developed a simple yet nontrivial queueing model to predict the dynamics among the operating and recovery rooms as a function of the number of recovery beds, surgery case volume, recovery time, and other parameters. They hypothesized that the model could predict the observed distribution of patients in recovery and on waitlists, and they used statistical goodness-of-fit methods to test this hypothesis against data from their hospital. Numerical simulations and a survey were used to better understand the applicability of the model assumptions in other hospitals.


RESULTS
Statistical tests cannot reject the prediction, and the model assumptions and predictions are in agreement with data. The survey and simulations suggest that the model is likely to be applicable at other hospitals. Small changes in capacity, such as addition of three beds (roughly 10% of capacity) are predicted to reduce waiting for recovery beds by approximately 60%. Conversely, even modest caseload increases could dramatically increase waiting.


CONCLUSIONS
A key managerial insight is that there is a sensitive relationship among caseload and number of recovery beds and the magnitude of recovery congestion. This is typical in highly utilized systems. The queueing approach is useful because it enables the investigation of future scenarios for which historical data are not directly applicable.
Schoenmeyr
Tor
T
Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA 02114, USA.
Dunn
Peter F
PF
Gamarnik
David
D
Levi
Retsef
R
Berger
David L
DL
Daily
Bethany J
BJ
Levine
Wilton C
WC
Sandberg
Warren S
WS
D000465:Algorithms; D003198:Computer Simulation; D006801:Humans; D017146:Models, Organizational; D009873:Operating Rooms / Q000458:organization & administration; D016134:Organizational Policy; D011997:Recovery Room / Q000458:organization & administration*; D013598:Systems Theory; D014850:Waiting Lists