Discrete Event Simulation Of Outpatient Flow In A...

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Discrete Event Simulation Of Outpatient Flow In A Phlebotomy Clinic INFORMS, 11/15/2016 Elizabeth Olin Ajaay Chandrasekaran Amy Cohn Carolina Typaldos

Transcript of Discrete Event Simulation Of Outpatient Flow In A...

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Discrete Event Simulation Of

Outpatient Flow In A Phlebotomy

Clinic

INFORMS, 11/15/2016

Elizabeth Olin Ajaay Chandrasekaran

Amy Cohn Carolina Typaldos

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Agenda

• Background: UMCCC / Phlebotomy Department

• Approach: Discrete Event Simulation

• Analysis: What-if Scenarios

• Future Work

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BACKGROUND

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UMHS Comprehensive Cancer Center

• Home to 17 multidisciplinary and 10 specialty clinics, organized by cancer type

• In 2015, over 50% of outpatient visits in the UMCCC resulted in chemotherapy infusion treatments:

– 97,147 outpatient visits

– 58,419 infusion treatments

• High outpatient demand for infusion causes:

– Process congestion

– Increased patient waiting times

– Overworked staff

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UMHS Comprehensive Cancer Center

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Patient

Arrives

Chemotherapy/

Infusion Clinic

Pharmacy

Drug

Preparation

Patient

Discharged Phlebotomy Labs Collected

Information Flow

Material Flow

Patient Flow

Lab Processing

• Patient visit to Cancer Center

– Often long, multi-step process

– Can take anywhere from 30 min to 8 hrs

– Requires multi department coordination

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Potential Delays at Infusion

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Patient

Arrives

Chemotherapy/

Infusion Clinic

Pharmacy

Drug

Preparation

Patient

Discharged Phlebotomy Labs Collected

Information Flow

Material Flow

Patient Flow

Lab Processing

DELAY

DELAY

DELAY

• Patient is late

• No infusion chairs are available

• Infusion drugs are unavailable

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Potential Delays at Clinic

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Patient

Arrives

Chemotherapy/

Infusion Clinic

Pharmacy

Drug

Preparation

Patient

Discharged Phlebotomy Labs Collected

Information Flow

Material Flow

Patient Flow

Lab Processing

DELAY

DELAY

DELAY

• Patient is late

• Clinicians are unavailable

• Patient blood draw results are not ready

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• Phlebotomist not available (check-in and/or draw)

• Chair not available

• Orders not ready

Potential Delays at Phlebotomy

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Patient

Arrives

Chemotherapy/

Infusion Clinic

Pharmacy

Drug

Preparation

Patient

Discharged Phlebotomy Labs Collected

Information Flow

Material Flow

Patient Flow

Lab Processing

DELAY

DELAY

DELAY

DELAY

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Patient

Arrives

Chemotherapy/

Infusion Clinic

Pharmacy

Drug

Preparation

Patient

Discharged Phlebotomy Labs Collected

Information Flow

Material Flow

Patient Flow

Lab Processing

Problem Statement

DELAY DELAY

DELAY DELAY DELAY

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Delays in phlebotomy can ripple through the system

DELAY

DELAY

DELAY

DELAY

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Our Goal

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Improve Phlebotomy process efficiency

and reduce patient wait times

to reduce overarching system delays

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Patient

Arrives

Chemotherapy

/ Infusion Clinic

Pharmacy

Drug

Preparation

Patient

Discharg

ed

Phlebotomy Labs Collected

Lab

Processing

Phlebotomy

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Phlebotomy

Patient

Arrives

Waiting

Area

Check-In

- Generally 2-3

Phlebotomists

Blood Draw

- Draws by port or

vein access

- Generally 5-6

Phlebotomists

Lab

Processing

Clinic

• Nearly all patients enter the system through phlebotomy

• Multi-step/ multi-wait process increased patient waits

• Blood drawn for labs needed:

– By provider before clinic appointment to assess patient

– By pharmacy to initiate drug preparation

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Phlebotomy

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• Large Waiting Room

• 3 Check-In Stations

• 9 Blood Draw Chairs

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Phlebotomy

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• Large Waiting Room

• 3 Check-In Stations

• 9 Blood Draw Chairs

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APPROACH

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Discrete Event Simulation

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• Computer Simulation Tool:

– Visualize and analyze current operations

– Test and measure the impact of different “what if" scenarios without having to carry them out

– Manipulate input parameters to observe effect on various metrics

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Discrete Event Simulation

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• User-specified

number of

iterations • 1 iteration = 1

simulated

“day”

• Based on • MiChart data

• Collected

data

• Expert

opinion

• Hospital

regulations

• Summary

statistics

• Metrics for

patients and

phlebotomists • Wait times

• Utilizations

Read Parameters

Run

Simulation Generate

Results

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Simulation Design

• Developed in C++

• Three (3) main event types, each corresponding to an availability queue:

– Patient Available for Check-In

– Patient Available for Blood Draw

– Phlebotomist Available

• As events occur, they are either completed or added to one of the availability queues

• Event Queue

– Events are created and added to queue during simulation

– Events in the queue complete in order (priority queue)

– While there are still events in the queue, continue completing them

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Base Case

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0

10

20

30

40

Pat

ien

t A

rriv

al R

ate

/ h

r.

Time of Day

Patient and Staff Volumes by Time of Day

Patient Arrival Rate

• Patient arrival distributions representing current uneven volumes

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Base Case

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0123456

0

10

20

30

40

Nu

mb

er

of

Ph

leb

oto

mis

ts

wo

rkin

g

Pat

ien

t A

rriv

al R

ate

/ h

r.

Time of Day

Patient and Staff Volumes by Time of Day

Draw Phlebotomists

Check-In Phlebotomists

Patient Arrival Rate

• Patient arrival distributions representing current uneven volumes

• Staffing levels based on current schedule (tailored to accommodate varying patient volumes)

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Base Case

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Mean Wait Time (m:ss)

Check-In Draw Total

Base

Case 2:52 8:21 11:14

0

1

2

3

4

5

6

0

5

10

15

20

25

30

35

40

Nu

mb

er

of

Ph

leb

oto

mis

ts

wo

rkin

g

Pat

ien

t A

rriv

al R

ate

/ h

r.

Time of Day

Service Times

Description Mean (Standard

Deviation)

Check-In 3.25 min (1.23 min)

Blood Draw 10 min (4 min)

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ANALYSIS

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What-if Analysis

• See system sensitivity to variations in input parameters

• Variable parameters:

– Patient arrival rates and volumes

– Staffing Decisions (Number of phlebotomists/ task allocation)

– Service Times

– Etc.

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What-if Analysis: Ideal Case

• Leveling system variability

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Scenario

Mean Wait Time (m:ss)

Check-In Draw Total

Base Case 2:52 8:21 11:14

Level Patient Arrivals 2:47 6:18 8:03

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What-if Analysis: Ideal Case

• Leveling system variability

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Scenario

Mean Wait Time (m:ss)

Check-In Draw Total

Base Case 2:52 8:21 11:14

Level Patient Arrivals 2:47 6:18 8:03

Level Arrivals & Adjust Staffing (20 arrivals/hr & 2 Check-in, 5 Draw all day) 1:18 1:28 2:47

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What-if Analysis: Patient Volume Increase

• UMCCC experiences consistent growth

– Can current capacity handle increase volume?

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Scenario

Mean Wait Time (mm:ss)

Check-In Draw Total

Base Case 2:52 8:21 11:14

+10%

Patient Volume 4:40 16:45 21:25

+20%

Patient Volume 7:24 28:45 36:10

+30%

Patient Volume 12:44 40:40 53:29

0

10

20

30

40

50

60

70

80

6:00 9:00 12:00 15:00

To

tal W

ait

(m

in)

Hour of Day

Average Total Wait by Time of Day

BaseCase

+10%

+20%

+30%

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Scenario (Assume Increased Volume Base Case: +20% Patient Volume)

Mean Wait Time (h:mm:ss)

Check-In Draw Total

No additional

Phlebotomist

Increased Volume Base Case:

+20% Patient Volume 7:24 28:45 36:10

- 1 Check-in Phlebotomist

+1 Draw Phlebotomist 1:47:15 5:32 1:42:43

1 Additional

Phlebotomist

+1 Draw Phlebotomist 7:32 6:29 14:01

+1 Check-in Phlebotomist 0:59 32:54 33:53

2 Additional

Phlebotomists

+1 Draw Phlebotomist

+1 Check-in Phlebotomist 0:58 10:35 11:34

What-if Analysis: Patient Volume Increase

• UMCCC experiences consistent growth

– Could staffing changes help accommodate?

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Conclusions

• Cancer Center patient visits can be long, multi-step processes

• Expected growth and bottlenecks in the current system necessitate process improvements

• Simulation techniques allow ‘what-if ’ analysis for improvements without impacting current system

• Results can

– Highlight issues

– Explore areas of potential improvement

– Support decisions for change implementation

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Future Work

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• Better representing reality (current state) with more accurate:

– Service time distributions

– Arrival rate data

– Non-instantaneous service transitions

– Phlebotomist roles

• Exploration of additional “what-if” scenarios

• Pilot study for implementation of improvements

• Additional applications (outside of Phlebotomy) of simulation design

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Acknowledgements

• Center for Healthcare Engineering and Patient Safety (CHEPS)

• Seth Bonder Foundation

• UMHS Comprehensive Cancer Center

• Research Collaborators

– CHEPS students and staff

– Cancer Center clinical collaborators and representatives (especially those from the Phlebotomy Department)

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QUESTIONS?

Thank you!

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CONTACT INFORMATION:

Elizabeth Olin – [email protected]

Amy Cohn – [email protected]

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Appendix

Service Times

Description Mean (Standard Deviation)

Check-In 3.25 min (1.23 min)

Blood Draw 10 min (4 min)

- 2015 PHLEBOTOMY TIME STUDIES

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Simulation Design

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Event Type Participant ID Time

PatientAvailCI 3948 7:03:42

PatientAvailCI 2084 7:06:12

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Simulation Design

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Event Type Participant ID Time

PatientAvailCI 3948 7:03:42

PatientAvailCI 2084 7:06:12

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Simulation Design

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Event Type Participant ID Time

PatientAvailCI 2084 7:06:12

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

3948 7:03:42

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Simulation Design

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Event Type Participant ID Time

PatientAvailCI 2084 7:06:12

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

3948 7:03:42

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Simulation Design

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Event Type Participant ID Time

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

3948 7:03:42

2084 7:06:12

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Simulation Design

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Event Type Participant ID Time

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

3948 7:03:42

2084 7:06:12

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Simulation Design

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Event Type Participant ID Time

PhlebAvail 0962 7:15:00

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

Event Queue

Participant ID Time

3948 7:03:42

2084 7:06:12

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Generate Service Time:

2 minutes 51 seconds

Clock

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Simulation Design

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Event Type Participant ID Time

PatientAvailCI 5541 7:16:09

PatientAvailCI 8737 7:20:33

PatientAvailBD 3948 7:17:51

PhlebAvail 0962 7:17:51

Event Queue

Participant ID Time

2084 7:06:12

PatientAvailCI

Queue Participant ID Time

PhlebAvail

Queue

Clock

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Appendix

• Phlebotomy – 253 patients per day

• Clinic (7 Total) – 311 patients per day

• Infusion – 123 patients per day

– 20% of infusion appointments are coupled

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Appendix

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• Staff Schedule