Abstract
Emergency department over-crowding has been a growing problem throughout the world. This paper presents a practical approach to estimate the waiting times for multi-class patients and apply the approach to reduce the waiting time for high priority patients. Patient flows with different levels of acuity are formulated based on the priority queue models. It derives explicit expressions of the wait time for the Markov queue and uses the concept of isomorphism to approximate the wait time in the general queue. Numerical results with simulation experiments are reported to display the accuracy of the approach. A case study from an emergency department indicates that the proposed approach can efficiently prioritize patient flows in decreasing waiting times. The queuing models have two features. First, the approximation applies to the general priority queues and reduces to the exact results of the Markov priority queue. Second, the models requires no iterative algorithm.