Discussion Questions
What is activity utilization at every step in the process? What is the direct labor utilization?
How is variability affecting capacity at the clinic? How can variability be controlled?
Where is the bottleneck in the process?
What are the capacity constraints at the clinic?
What is the economic cost of wait times?
What recommendations would you make and why?
THE CLINIC
The Paediatric Orthopaedic Clinic is a treatment centre that is jointly managed by the
Children’s Hospital of Western Ontario and the Division of Surgery, both a part of the
London Health Sciences Centre. The clinic operated from 8:30 a.m. to 1:00 p.m. and
accepted only patients only with prior appointments. On a typical day, 80 patients pass
through the clinic; 40 per cent are new patients and 60 per cent are follow-up patients.
Exhibit TN-1 summarizes this patient mix.
The process flow involves four major steps: front desk, radiology department, return to
clinic and finally the examination room. Exhibit TN-2 portrays these steps as a process
flow diagram. The diagram shows the activities involved in these steps, patient splits and
information flow (i.e. front office versus back office).
PROCESS PERFORMANCE METRICS
Activity Utilization
If each activity is considered in isolation, we estimate activity utilization as time required
for each activity divided by total time available for that activity.
Activity Utilization = Time required / Time available
Exhibit TN-3 summarizes the activity utilization at each of the four steps.
Front Desk
Two activities are carried out at the front desk. The first activity, registration, has three
clerks who work for 180 minutes each; thus, the total time available is 540 minutes. The
time required per patient is five minutes, and the total number of patients that can be
registered in a given session duration is 108 patients (i.e. 540 5). With 80 patients per
session, activity utilization is 80 108 = 74 per cent.
Three nurses handle the second activity, verification of documents, at the front desk. The
total time available for the three nurses is 765 minutes per session with each nurse working
255 minutes (i.e. 8:30 a.m. to 12:45 p.m.). The time required for verification is 11 minutes
per new patient and five minutes per follow-up patient respectively.
Radiology Department
Three activities are performed in the radiology department. First, six technicians operate
X-rays machines for imaging. Given that only two-thirds of the radiology department’s
time is available for the paediatric clinic, the total available time is 960 minutes, i.e., 2/3 6
240. On average, an image takes 11 minutes each (including periodic adjustment for a
different type of X-ray) for new patients, nine for follow-up. With 32 new patients and 48
follow-up patients, the total required time is 784 minutes. Thus, utilization is 82 per cent.
The second activity, X-ray development, is an automated activity that requires seven
minutes. Because the X-ray equipment could simultaneously take new images and develop
earlier images, again the total time
available is 960 minutes. Of this time, only 560 minutes is needed, yielding a utilization of
58 per cent.
Three radiologists perform the third activity, X-ray diagnostics. A radiologist takes about
five minutes to review and annotate the image for a new patient. As with the X-ray
equipment, only two-thirds of the radiologists’ time is available for the clinic’s patients.
Hence, the total time available is 480 minutes, i.e., 2/3 3 240. Of this available time, only
352 minutes is needed, giving a utilization of 73 per cent.
Return to Clinic
An additional nurse directed patients, at two minutes per patient, yielding a total of 160
minutes. As the nurse was available for 255 minutes, the utilization was 63 per cent.
Examination Room
The examination room encompassed two main activities: medical examination and cast
application/removal. The surgeon examined all new patients (seven minutes per patient)
and about 30 per cent of the follow-up patients (four minutes per patient), which translated
into 282 minutes. However, the total time available was only 255 minutes, which indicates
that the surgeon was overloaded, with a utilization of 110 per cent. In contrast, only one
senior resident examined the remaining 70 per cent of follow-up patients (seven minutes
per patient). So for this individual, the utilization is only 92 per cent, i.e., 0.7 48 7 255.
Overall Utilization for Direct Labor
From Exhibit TN-3, we aggregate the activities that involve direct labor (all activities
except automated X- ray development). The total time available for direct labor activity is
4,470 minutes, and the total time available is 3,365 minutes. Therefore, overall utilization
of direct labor was 75 per cent.
Bottleneck
Two options can be used to identify a bottleneck based on utilization: any activity or
operation with utilization exceeding 100 per cent (i.e. The Goal); or the activity with the
highest utilization. Only the surgeon has utilization in excess of 100 per cent.
Throughput Time
Throughput time is the total time (i.e. activity + wait time) for a patient to move through
the entire process. To determine the throughput time for new patients, the reported time by
patients (processing time and wait times) can be aggregated across all steps (see case
Exhibit 3). Thus, the average throughput time for new patients is 129 minutes, and for
follow-up patients is 119 minutes. Therefore, overall throughput time is 123 minutes, i.e.,
0.4129 + 0.6119.
Proportion of Wait Times in Each Activity
From case Exhibit 3, we know the total time (i.e. wait + activity) that a patient spends at
