Computer simulation analysis of blood donor queueing problems.

A computer simulation model was used to study work flow and queueing problems in blood collection. Donor scheduling strategies, such as stream and block arrivals, were compared with random arrival at a constant hourly rate. Controlling donor queueing required keeping donor arrivals from exceeding the system capacity, rather than using any one type of scheduling strategy. However, widely uneven arrivals compared to even arrivals at the same input level caused protracted queueing. Because men have a shorter average phlebotomy processing time, time can be saved in some situations by scheduling mostly men at the beginning of a drive. Nursing utilization appears optimal at donor arrival rates at or near system capacity. Techniques may be available to modify the collection system to ameliorate or prevent queueing when donor arrivals appear to be excessive.