EMERGENCY SERVICE:A

GENERALIZED FLEXIBLE

SIMULATION MODEL

Paola FACCHIN Department of Paediatrics, University of Padova, Italy

Giorgio ROMANIN JACUR Department of Management and Engineering, University of Padova, Italy

AIRO 2003

EMERGENCY SERVICE 1

Any emergency service:

• is devoted to supply first aid to outpatients

• may alternatively serve:

– a hospital or a group of hospitals,

– a department or a group of departments,

according either to pathologies (e.g.,

obstetrics, surgery) or to types of patients

(e.g., neonatology, paediatrics)

EMERGENCY SERVICE 2

Any emergency service is characterized by:

• high variability of patient arrivals, depending on:

– time (different intervals of the day, week, year)

– randomness (e.g., accidents, weather,

epidemics)

• hard requirements for:

– quick (sometimes immediate) response, also in

case of congestion

EMERGENCY SERVICE 3

Any emergency service shall be correctly designed

and managed for what concerns:

• structures (major treatment rooms, minor treatment

rooms, beds)

• technological resources (specifical instruments)

• human resources (doctors,nurses, engineers and

related working rules, turns of duty, etc.)

in order to supply a high quality service at minimum

cost

EMERGENCY SERVICE 4

Discrete simulation may be a useful tool:

• in the design phase, to find the right dimension of

employed structures and resources

• in the working phase, to analyze, check and

possibly adapt the system behaviour

Discrete simulation requires to:

• build up a model with the right level of detail

• implement it in a friendly language

PAPER CONTRIBUTION

• We build up a generalized flexible model, able to

correctly describe many existing emergency

services, by adjusting fundamental parameters

• We implement it by specialized software Micro

Saint, which presents a good compromise

between abstraction level and user friendliness,

and therefore may be easily employed both by

those who adapt the general model to the

particular application and those who utilize the

application for design or management

ARRIVALS

ARRIVALS

TRIAGE

QUEUE

QUEUE

QUEUE

QUEUE

SERVICE

SERVICE

SERVICE

SERVICE

EXTERNAL

SERVICE EXTERNAL

ARRIVALS QUEUE

RESOURCES:

DOCTORS

NURSES

INSTRUMENTS

OUT

OUT

EXTERNALS

EMERGENCY SERVICE GENERAL MODEL (LOW DETAIL)

ARRIVALS 1ARRIVALS 1

ARRIVALS 2ARRIVALS 2

TRIAGE

QUEUE

QUEUE

QUEUE

QUEUE

SERVICE

SERVICE

SERVICE

SERVICE

EXTERNAL

SERVICE EXTERNAL

ARRIVALS QUEUE

RESOURCES:

DOCTORS

NURSES

INSTRUMENTS

OUT

OUT

EXTERNALS

EMERGENCY SERVICE MODEL ARRIVALS

EMERGENCY SERVICE MODEL ARRIVALS

“Average arrivals”:• random independent• time dependent mean• groupable in classes (to be defined now)

“Special arrivals” (e.g., epidemics, extraordinary weather):• randomness to be defined according to the particular case• time dependency to be defined according to the particular case “Pseudo arrivals”:• change of orders (deterministically at every duty change)• other

ARRIVALS

ARRIVALS

TRIAGETRIAGE

QUEUE

QUEUE

QUEUE

QUEUE

SERVICE

SERVICE

SERVICE

SERVICE

EXTERNAL

SERVICE EXTERNAL

ARRIVALS QUEUE

RESOURCES:

DOCTORS

NURSES

INSTRUMENTS

OUT

OUT

EXTERNALS

EMERGENCY SERVICE ARRIVAL SELECTION (TRIAGE)

EMERGENCY SERVICE ARRIVAL SELECTION (TRIAGE)

All arrivals are selected by the same unique filter (triage) which is ruled by specialized nurses

The selection is based on the presented life parameters (predefined and universal) which determine the immediate life danger

The selection assignes a colour code, according to immediate life danger, and related urgency:red code, aid shall be immediate, any wait may cause deathyellow code, aid shall not be delayed more than some minutes, wait may increase severitygreen code, aid may be delayed, a limited wait (tenth of minutes) is permitted without dangerwhite code, no life danger, any wait cannot cause damage

PATIENT ROUTING AND SUPPLIED SERVICES

According to the assigned colour code the patient is characterized by:• different routing• different treatments• different resources utilized• different service time• different priority and possible preemption in the queues, in particular for external services, if required

ARRIVALS

ARRIVALS

TRIAGETRIAGE

QUEUEQUEUE

QUEUE

QUEUE

QUEUE

SERVICESERVICE

SERVICE

SERVICE

SERVICE

EXTERNAL EXTERNAL SERVICESERVICE

EXTERNAL

ARRIVALS QUEUEQUEUE

RESOURCES:RESOURCES:

DOCTORS

NURSES

INSTRUMENTS

OUT

OUT

EXTERNALS

PATIENT ROUTING AND SUPPLIED SERVICES

RESOURCES AT DISPOSITION

DOCTORS• duty chief = responsible of the service• (possible) assistant(s) on duty• available within minutes (e.g., ten, twenty)• working in external services

NURSES• triage nurses• nurses on duty

STRUCTURES AND INSTRUMENTATION• Major treatment room(s)• Minor treatment room(s)• Special instruments

MODEL IMPLEMENTATION BY SW MICRO SAINTMicro Saint is based on task network modelling

MODEL IMPLEMENTATION BY SW MICRO SAINTNetwork is easily built up by a CAD method

MODEL IMPLEMENTATION BY SW MICRO SAINTMain elements of networks are tasks, decisions and queues

MODEL IMPLEMENTATION BY SW MICRO SAINTExample of task description

MODEL IMPLEMENTATION BY SW MICRO SAINTExample of description of a decision

MODEL IMPLEMENTATION BY SW MICRO SAINTExample of queue description

MICRO SAINT MODEL NETWORK

MICRO SAINT MODEL NETWORK: ARRIVALS AND TRIAGE

MICRO SAINT MODEL NETWORK: EXTERNAL SERVICES

MICRO SAINT MODEL NETWORK: RED CODE

MICRO SAINT MODEL NETWORK: YELLOW CODE

MICRO SAINT MODEL NETWORK: GREEN CODE

MICRO SAINT MODEL NETWORK: WHITE CODE

MICRO SAINT MODEL NETWORK: DATA DEFINITION

ARRIVALS are ruled by all time dependency parametersTRIAGE chooses different routing for every patient groupPATIENT ROUTING defines access to resources and to external services and related priorities (and preemption)RESOURCES WHICH MAY BE SEIZED, PRIORITY AND PREEMPTION are different for the various patient groupsEXTERNAL SERVICE UTILIZATION are ruled by time dependency and different priority for the patientsHUMAN RESOURCE PRESENCE is ruled by turns of duty

ALL ABOVE PARAMETERS ARE ADJUSTED IN ORDER TO CORRECTLY DESCRIBE THE ACTUAL STUDIED SERVICE

MICRO SAINT MODEL NETWORK: SIMULATION RESULTS ABOUT A QUEUE

MICRO SAINT MODEL NETWORK: SIMULATION RESULTS

Results report:flow times queues parametersresource utilization

They may be supplied referred to:single groups whole performance

CONCLUSIONS

The presented model has been tested on an actual

service

It is sufficiently detailedsufficiently detailed and extremely flexibleflexible,

therefore it may be easily employed to simulate

different emergency services

It is a useful managing instrumentmanaging instrument to improve the

service performance, as it permits to detect all

possible critical points and consequently to suggest

suitable correcting actions

The presented model has been tested on an actual

service

It is sufficiently detailedsufficiently detailed and extremely flexibleflexible,

therefore it may be easily employed to simulate

different emergency services

It is a useful managing instrumentmanaging instrument to improve the

service performance, as it permits to detect all

possible critical points and consequently to suggest

suitable correcting actions