Scheduling Medical Operations

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Scheduling Medical Operations

• 7th International Workshop on Human Factors in
  Planning, Scheduling and Control in Manufacturing
  
• Groningen, June 13-15, 2005
• By Philip Ruttle

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Backround - Motivation
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Reported number of patients waiting for elective
treatment, quarterly, March 1993 to December 2002
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Expenditure under the Waiting List Initiative,
1993 to 2002(strategic workaround send patients
elsewhere)
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Waiting Times for Elective Surgeries
Current Situation wait for more than 3 in 4
patients is gt 4 months
The Aspired Target none gt 4 months!
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Problems on the Ground Experienced by Surgeons

• Example
• Salient context
• Coronary by-pass operations
• Situation
• Surgical team gowned up
• Theatre ready
• Problem No patient
• Consequence Operation cancelled
• Why?
• No porter available
• Occurrence one of many issues of annoyance
• something must be done can someone look into
  this
• potential opportunity

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Operations Scheduler Activity Goals?
How do you improve one without NEGATIVELY
affecting the others? Assumption Currently focus
is on trade-offs Aspiration improve on all
fronts. (Improve on Pareto Optimality)
Constraints
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Work Plan Personal Criteria

• To be novel
• To be useful
• To be field-based
• To add to knowledge at conceptual/abstract level
• To be valid

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Work Plan Line of Attack
2 Pronged Approach
Long term Interfacing/supporting
process Abstraction Frameworks General Application
to support system design Future processes/future
system?

• Short term
• Attention to the tangible
• Process intervention at physical level
• Build interest
• Low Hanging Fruit
• Limited conceptual depth?

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Plan (Short-Term)

• Speculative

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Plan (Short-Term)

• Observe suggest process control (queue
  discipline?) intervention
• Who, What, When, Where, How, Why.
• Current process structure
• Constraints
• First conventional
• deepen
• Process Times (measurable ?)
• Setups/ changeovers (measurable ?)
• Associated Variability
• TOC packaging after
• identify spare capacity/queue control
  intervention? (emergent from TOC observations)
• Why? - Tangible gains build interest/cooperation
  
• Karvonen, S., et al., Productivity improvement
  in heart surgery - a case study on care process
  development. Production Planning Control, 2004,
  Vol. 15, 238

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Who, What, When, Where, How.

• Gain Basic Knowledge of the Process
• Is an Entry Level Analysis
• Technical ordering
• Production Flow Analysis
• Locus of decision/activation
• Who currently does it (actors)
• Where
• Timing
• When/how often
• Conditions under which taken
• Situations/pressures
• Limitations/ constraints
• Data (and quality)
• Objectives of activities
• Process physics

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Data Collection

• existing records where available
• activity sampling
• structured interviews
• critical incident technique

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Process Times

• Whats the underlying distribution?
• Gamma
• Seung-Chul, K., et al., Flexible bed allocation
  and performance in the intensive care unit.
  Journal of Operations Management, 2000, Vol.
  18(4), 427.
• Lognormal
• Spangler, W., et al., Estimating Procedure Times
  for Surgeries by Determining Location Parameters
  for the Lognormal Model. Health Care Management
  Science, 2004, Vol. 7(2), 97.
• Conclusion Are definitely Skewed
• Few very short
• Many in central region
• Few very long
• Many questions not answered
• Eg how much variation lies on a predicted value
• Possibilities for reducing error ranges

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Process Times

• How do you Predict it
• Factors to Consider
• The procedure
• The Surgeon
• Training
• What are its Constituent Parts
• Set-up
• Preparation
• Anaesthesia
• Operation
• Recovery

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Variability

• Variability underlies WIP Hopp and Spearman,
  Factory Physics
• i.e. patient queues
• Demand Uncertainties
• Process Times
• Predicted vs. Actual
• Analogy reverse manufacturing /disassembly
• Changeover Time
• Shingo, Non-stock Production
• Monden, The Toyota Production System
• Variability as a Source of Waste (7 forms of
  waste etc )
• Smooth Flow
• as a Virtuous Circle
• How Achievable? more in the aspiration than in
  reality?
• Neglected?
• Variety Urgency

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Flow (TOC)

• Patient flow
• What are the Resources
• What are the activity Sequences
• What are their volumes and capacities
• Which are Constraining
• Are they Static/Dynamic
• Discrete/continuous

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Setups

• Magnitude
• Potential for capacity-making
• Structure
• Set-up
• Preparation
• Are Setups Sequence Dependant?
• What Causes the Dependancy
• Can Setup Time be Reduced?
• What Parts are External and Internal

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Longer Term

• highly speculative

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Karvonen et al (2004)

• Very specific opportunity for research
  collaboration
• Mix of socio and technical
• Cross-dept
• TOC (search)
• Process flow (PFA / Burbidge)
• Bottleneck
• Process Opportunity to make use of spare
  safety-stock capacity
• Solution
• Subordinate to this to the givens
• Two-queue
• Improve system
• Organisation change
• Tangible Result
• Dramatic improvement in queue length
• improvement in patient health outcomes not
  measurable
• This was their outcome path specific to them

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• Missing-
• Human decision-making process

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Longer Term

• Work Needs interpretational frameworks -
  conceptual

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Work Domain Analysis (Goals and Players)
(Higgins/Vicente-Rasmussen)
Whole Parts
Purpose Physical
Abstraction Hierarchy
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McKay 7-step process
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Plan (Long-Term)Follow this route (Higgins)
Decision Ladder Activate Observe Identify Interpre
t Evaluate Task Process Implement
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• Open for ideas