On the risk of premature transfer from coronary care units

When a coronary care unit becomes full, an existing patient will be transferred out of intensive care and into a general medical or surgical ward in order to make room for the next arrival. The patient transferred may have suffered a heart attack and still be at risk whilst the next patient admitted may subsequently be diagnosed to have nothing more serious than indigestion. Queueing theory is used to develop a model which predicts the proportion of patients from each diagnostic or risk category that would be prematurely transferred as a function of the size of the unit, number of risk categories, mean arrival rates, and length of stay. A case study is used to demonstrate how the model parameters have been estimated and the operating characteristics determined for a particular unit.