Page 464 - Design for Six Sigma for Service (Six SIGMA Operational Methods)

422 Chapter Twelve

Blockage Starved
Constraint process step
Figure 12.7 Symptoms of a Constraint

referral, appointment making, joining the waiting lists, and discharge in this
mock system are all steps where large numbers of patients can be processed
within a given time. The outpatient consultation and the follow-up visit are
lower-volume steps where fewer patients are dealt with in the same period of
time. The lowest throughput of all, however, is at the surgery stage. This is the
step that constitutes the bottleneck or constraint in this fictitious patient
pathway. No matter how many more patients are being dealt with at any of the
other stages, the process cannot be speeded up so long as the surgery stage
remains incapable of increasing its throughput.

No matter how hard clinicians and managers in this particular example try to
improve throughput elsewhere in the system, they will never succeed in driving
down waiting lists if the surgery stage remains incapable of processing more
patients in a given time. In fact, any efforts to improve matters could actually
lead to bigger waiting lists for surgery.

12.3.2 Decide How to Exploit the Identified Constraint

Once you have found where the constraint is, you should decide what to do
with it. First, you may have to do more investigation on what kind of con-
straint it is. Is it a policy, resource, or material constraint? The following are
some ideas of how to deal with the constraint:
• If it is a policy constraint, find a better way to do the job, such as was
illustrated in Example 12.2.
• Increase the capacity of the constraint.
• Ensure well-trained and cross-trained employees are available to
operate and maintain this constraint.

Appointment Outpatient Add to Follow-up
GP referral Surgery Discharge
made visit waiting list visit
100 100 50 150 15 60 140
Theoretical numbers of patients that can be processed at each step
Figure 12.8 A Constraint in a Hospital