1. Queue, Demand, Capacity, Variation and Flow
Essential measures for clinicians and managers

3. The queue
Queues occur where demand has not been dealt with resulting in a backlog of work.
The main reasons why queues develop is the mismatch between the variation in demand and capacity at specific times

4. The queue The NHS is a classic queue system
We place patients in queues all the time
some patients are in multiple queues

5. The queue
Every time the demands exceeds the capacity a queue is formed but
Whenever capacity exceeds demand the extra capacity is lost or it is filled from the queue – often at short notice
Filling slots at short notice can lead to longer waiting times and distort clinical priorities

6. Managing the queue - using evidence based tools
Ensure an element of patient choice in the booking process
Use referral information services or referral management services
Ensure waiting list data is accurate
Reduce unnecessary “carve out”

7. Managing the queue
Take unnamed referrals –refer to a service not a clinician
Pool referrals
Pool waiting lists
See people in clinical and date order

9. Defining demand, capacity activity and queue
Demand on the services is all the requests or referrals into the service from all sources
Capacity is all of the resources required to do the work and includes staff and equipment
Activity is the work done, it is the throughput of the system
Backlog is the demand which has not been dealt with – the queue or waiting list

10. Demand and capacity definitions:
Waiting list, queue
= what we should have done
Demand
= All requests
for a service =
what we should do
Capacity
= what we could do
Activity
= what we did

11. Measuring demand, capacity activity and queue
Why is it important to understand the four measures of demand, capacity, activity and queue?
To identify the bottleneck or constraint in the care process
To increase capacity at the stage of the process where it will create the greatest outcome
To reduce inappropriate demand to the constraint
To redesign services or plan services

12. Measuring demand, capacity, activity and queue
Must be measured in the same units of time for the same period i.e. hourly, over a 24 hour period, weekly or monthly
It is not possible to compare two or more items unless they are measured in the same unit of time
It is important to compare the four measures on a single graph

13. Measure demand
Multiply the number of patients referred from all sources by the time taken in minutes to process a patient
Understand your demand – what it is (shape) and where it comes from (source)

14. Manage demand Right person, right place, right time
Understand and manage activity and capacity to meet changes in demand i.e. seasonal variation

15. Measure capacity
Multiply the number of pieces of equipment by the time available in minutes available to the people with the necessary skills to use it

16. Measure activity
Multiply the number of patients processed by the time in minutes it took to process each patient

17. Measure the backlog or queue
Multiply the number of patients waiting by the time it will take in minutes to process a patient

18. Compare the four measures
Convert the data on demand, capacity, activity and backlog or queue onto a common line graph

19. If av. Demand = av. Capacity, variation mismatch = queue
time
Demand
Capacity
Can’t pass
unused capacity
forward

21. Understanding flow
In the NHS flow is the movement of patients, information or equipment between departments, staff groups or organisations as part of their pathway of care
Whilst process mapping looks at care processes from the patients perspective, flow analysis looks at the care process from a unit or departmental perspective

22. Flow modelling
Supports service improvement – at specific bottlenecks or constraints, in specific clinical areas, or across whole health systems
This tool will not tell you what should change – process mapping helps with identifying that
Flow modelling will show how well scarce resources are being used and how much room there is for improvement

23. How to build the flow model
Define the patient group to be analysed and define the start and end points of the flow map
In straightforward care processes a process map and process times will provide sufficient information to examine patient flow
The Unscheduled Care Collaborative made extensive use of flow mapping and modelling

24. Understanding variation
Why is it important to understand variation
Because the mismatch between the variation in demand and capacity is one of the main reasons that queues occur in the NHS

26. What variability? GP Number of patients Number of problems
Investigations
Length of appointments

27. What variability? Outpatients Number of referrals Number of staff
Investigations needed
Length of consultation

28. What variability? Ward -Length of pre-admission stay
-Length of post-op stay
-Intensity of nursing required
-Staffing levels

29. Variability Theatre Number of cases Length of cases Anaesthetic time
Recovery time
Turnaround time

30. Bed availability - an example of the
problem of variation
ADMISSION
IN-PATIENT STAY
DISCHARGE
Variation in patient pathways and processes.
E.g. in Length of Stay
Variation in Discharge - By time of day
- By day of week
- Seasonal variations
Variation in Admission Patterns - particularly for Elective Care

31. ADMISSION IN-PATIENT STAY DISCHARGE
“We always bring
our hips in on Tuesday !”
ADMISSION
IN-PATIENT STAY
DISCHARGE
Variation in Admission Patterns - particularly for Elective Care
Variation in Discharge - By time of day
- By day of week
- Seasonal variations
Variation in patient pathways and processes.
E.g. in Length of Stay

33. Understanding demand and capacity by hour of the day

37. Analysing variation Statistical Process Control Two types of variation
Common cause – that which is natural and to be expected
Special cause – which produces unusual or unexpected variation

38. Statistical process control
Two basic charts
The run chart – a line graph – an ideal method of comparing sets of data
The control chart – also run charts but with two distinct differences i.e.

40. Any questions?