Managing Variation,
Understanding the Effects of
Carve-out, Scheduling and Flow
How do we manage variation in
demand?
• Delay
• Forced booking
• Carved out capacity
Carve-out can be…
2 week wait
Urgent
Soon
Routine
Urgent follow-up
Routine follow-up
Secretary
Post-op
Number of
appointment
types
Huge
Number of doctors
Thousands of combinations
It is impossible to
balance the queues
The size of
the carve out
Flexi-sig
urgent x x x x x x x x x
soon
x x x x x x x x x
routine x x x x x x x x x
x x x x
x x x x
soon
routine x x x x
Colonoscopy urgent
OGD
ERCP
Number of
specialists
x x
x x
x x
urgent x x x x x x x x x
soon
x x x x x x x x x
routine x x x x x x x x x
Number of
appointment
types
x
73 queues
Queue type A
Queue type B
Server
Server
Server
Server
Server
Server
Server
Server
Is all carve-out bad?
• Capacity for urgent cases (prioritisation of
patients)
• Subspecialisation
• The issue is not to eliminate all carve-out, but
rather to eliminate unnecessary carve-out and
reduce the impact of carve-out we can’t
eliminate
Terms
Carve-out
When the flow of one group of patients is improved
at one bottleneck at the expense of another group of
patients
Streaming or segmentation
Separation of the process of care along the whole
pathway for one group of patients to improve overall
flow but not at the expense of other groups of
patients
Analogy of segmentation and flow:
traffic flow on motorway
Slow lane
50 mph
Middle lane
70 mph
Fast lane
90 mph
All vehicles keep to same speed in allocated lane
and all progress according to their need
What happens when lorry moves into
middle lane at 55 mph?
Slow lane
50 mph
Middle lane
70 mph
Fast lane
90 mph
• backlog of traffic • flow rates compromised • few needs met
• actual consequences are not seen at point of bottleneck
When is it carve-out?
• When ring-fencing resources for one group
reduces resource available for another group
• How can we tell whether the problem is carveout or capacity?
Demand exceeds capacity
Numbers
waiting will
go up
>
If Demand
400
350
30
25
300
20
250
200
Activity or Capacity
15
150
10
100
5
50
0
0
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Waiting
times will
go up
Carve out and churn
Number
waiting is
constant
over time
=
If Demand
250
30
25
urgent
200
Activity
20
150
15
100
10
50
routine
5
0
0
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
But waiting
times may not
be
“Skimming off the froth”
Variation and carve-out
• Variation helps cause the waiting list
• Carve out makes it worse
• So what are we to do?
Match capacity and demand!
• Set the maximum waiting time to the time
the most urgent referral can afford to wait
– Do today’s work today
– Do this week’s work this week
– Do this month’s work this month
What do we want to achieve?
• Maximise Throughput
Bypatients
keepingwith
every
• Treat the maximum number of
the
minimum amount of waitingmachine and person
working flat out
Wrong
• How?
Utilisation = efficiency
Sweat the
assets!
Flow
• We need to optimise the whole process - not
each individual step
• Don’t maximise utilisation, maximise throughput
• Manage the flow
How long does a scan take?
• Multiple queues
• Multiple slot types
»
»
»
»
arthrogram
thorax with contrast
spine
thorax
• Eliminate the carve-out
Build new CT templates
Prepare
patient
Scan
patient
Get off
scanner
Report
Films
Type
Report
20 minutes - “Quickie”
Prepare
patient
Scan
patient
Scan
patient
Contrast
40 minutes - “Longie”
Get off
scanner
Report
Films
Type
Report
Monitor progress
CT Demand/Activity/Capacity and Backlog
700
600
500
capacity
400
300
200
demand
b acklog
activity
March
February
January
December
November
October
100
0
Matrix Allocation: Step 1
Draw a matrix
Condition 1
Condition 2
Condition 3
Condition 4
Condition 5
Consultant FF
Consultant EE
Consultant DD
Consultant CC
Consultant BB
Consultant AA
Condition 6
Step 2
Fill in the matrix
x
x
Condition 4
x x
x x x
Consultant FF
x x x x x x
Consultant EE
Condition 6
Consultant AA
Condition 5
consultant
x x x
Consultant DD
Condition 3
x
Consultant CC
Condition 2
x
Consultant BB
Condition 1
Ensure all
conditions have at
least one
Step 3
Establish clinical care groups
x
x
Condition 4
x x
ccg 1
ccg 2
x x x
Consultant FF
x x x x x x
Consultant EE
Condition 6
Consultant AA
Condition 5
x x x
Consultant DD
Condition 3
x
Consultant CC
Condition 2
x
Consultant BB
Condition 1
Consultant FF
Consultant EE
Consultant DD
Consultant CC
Consultant BB
Consultant AA
Patient with
condition 4
Step 3
Allocate patients
Clinical care
group 4
40
35
30
25
20
15
10
5
0
70
Ophthalmology Outpatient Waiting List
vs List for patients booked in turn
60
50
Actual Outpatient Waiting List
40
30
20
10
0
44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10
Wait (weeks)
8
6
4
2
0
Number
Booked in Turn
Scheduling
You cannot schedule your way out
of a capacity problem...
What doesn’t scheduling do?
• Solve problems of a mismatch of capacity
and demand
• Deal with unusual events
Define capacity and demand:
Demand:
200 patients
per month
Capacity:
180 patients
per month
Backlog:
350
patients
Activity:
160 patients
per month
Scheduling will not
resolve this problem
The solutions:
• Increase Capacity to match Demand
• Decrease Demand to match Capacity
• There are no other options!
Define capacity and demand:
Demand:
200 patients
per month
Capacity:
240 patients
per month
Backlog:
350
patients
Activity:
160 patients
per month
But it might solve
this one...
An example of scheduling the bottleneck
Flexi-sigmoidoscopy
Prepare bowel
Prepare
patient
Write
notes
Scope
Patient
Nurse
Endoscopist
Recover balance
Identify the
- number of people
- number of rooms
- pieces of equipment available
2 loos for preparation
1 theatre for scoping
1 nurse for preparation
1 scoper for scoping and writing notes
4 recovery chairs for recovering balance
Line up the templates
Wasted time
Only 4 patients done
Only 1
endoscopist, so
Only 2 loos, so
cannot start 2nd
cannot start the
patient till
third patient until
endoscopist free
a loo is free!
endoscopist
can’t start
till late
What is the constraint? (defining capacity)
What is the bottleneck? (current limit on activity)
What solutions can you suggest?
• Add another endoscopy suite
Add more toilets
Get patients to do the bowel prep at
home
J
Fix the loos and set new templates…
11 patients done in
the same time!
Appointment times
set so that the endoscopist
starts
on time the template
Schedule
around the constraint
What are the risks?
• Some patients will not come fully prepared
• They will have to be rescheduled to another day or
at the end of the clinic
• Do not schedule to 100% utilisation of the scarcest
resource
• Do you want to fly in a plane that is scheduled to
use 99% of the available fuel to get to its
destination?
• Remember that capacity is 80% of the fluctuation
in demand
The road to ruin:
Capacity plans and contracts
based on average past activity
Fail to account for
variation in demand
Fail to deliver
required activity
Income less
than expected
+
Fail to account for
variation in capacity
Guarantee waiting
times beyond emergency
and elective targets
Increased
variations
in capacity
Reduces
effective
capacity
Increase staff overtime
& waiting list initiatives
Increased costs
Cost cutting
initiatives
The road to financial health
Capacity planning and contracts
based on variation in demand
Required activity
guaranteed
No waiting beyond
emergency or
elective targets
Income guaranteed
Costs controlled
Staff capacity to reduce
variation in capacity
increases
productivity