Patient mix optimisation and resource allocation : a case study in cardiothoracic surgery planning

Cardiothoracic surgery planning involves different resources such as operating theatre time, beds, IC beds and nursing staff. In practice the planning in the Thorax Centre focuses on optimal use of operating theatre time, though the performance of the Thorax Centre as a whole is often more limited by the capacity of the IC. For operating theatres a master surgical schedule is used to allocate operating theatre resources at tactical level for a longer period. Operational schedules at weekly level are derived from this master schedule. Within cardiothoracic surgery different categories of patients can be distinguished on behalf of their requirement of resources. The mix of patients is, therefore, an important decision variable for the Thorax Centre to manage the use of these resources. In the paper we will consider the planning problem to generate a master operation schedule that realises a given target of patient throughput and optimises an object function for the utilisation of resources. This problem can be mathematically approached by mixed integer programming. We will discuss the mathematical model developed for this planning problem, the implementation in a decision support model for tactical surgery planning, the results obtained and the way the model can help to broaden the focus of planning of cardiothoracic patients.