Figure 3.

Multiphase healthcare system sequencing tasks leading to an open- loop system as uncontrollable queues develop. The green areas show the acceptable mean waiting times for patients. The red areas depicts unacceptable mean waiting times. The arrows represent patient flows. At the first workstation, both variable and uncertain inter-arrival and process times develop. When patients are finished at this first workstation, they enter the next queue, and this continues. The result is that the uncertainty and variety at the workstation are without control and are not communicated to the subsequent workstations. Without integrated control, the queues can even amplify. For the sequencing of tasks, care pathways need integrated control [21].