Hospital's instability wedges.

In this study, we define a hospital congestion episode as a situation where the number of new patients needing admission is greater than the number of available beds in the hospital, and investigate the likelihood that the current day's midnight occupancy will exceed any specified threshold level. We demonstrate that this measure of risk exhibits a characteristic sensitivity phenomenon that we have named as hospital's instability wedge. In particular, it is seen that frequently even small changes in the numbers of patients admitted or discharged can dramatically change the risk of exceeding the threshold, thereby changing the risk of subsequent congestion episodes. While this finding captures a salient difficulty of operating a modern public hospital, it also opens up an opportunity for monitoring and alleviating the above defined risk with only small changes in admission, discharge, and cancellation rates. A case study with recent patient journey data from Flinders Medical Centre in South Australia is presented.