waste not; want not - pharmacyadvisor.com · usmp/mg1/14-0227 6/14 lean based on toyota production...
TRANSCRIPT
Waste Not; Want NotUtilizing Lean Concepts to Reduce IV Waste
USMP/MG1/14-0227 6/14
Utilizing Lean Concepts to Reduce IV Waste
Frank M. McCloy, R.Ph.
Sterile Products Supervisor
East Jefferson General Hospital
Metairie, Louisiana
Donna Carbajal, RN, RRT, MBA
Supervisor, Clinical Excellence
USMP/MG1/14-0227 6/14
We Welcome Your Questions
� You can submit questions throughout the webinar
using the form on your screen.
� If you experience any technical issues during the
webinar, please use the help button shown on your
screen.
� Download a PDF handout of the presentation on the
PharmacyAdvisor.com web page where you clicked
to join today’s webinar.
2
USMP/MG1/14-0227 6/14
Disclosure
� The content of this presentation was created by the
presenters and does not necessarily reflect the views
of Baxter Healthcare Corporation.
� Our speakers have accepted an honorarium from
Baxter for this presentation.
3
USMP/MG1/14-0227 6/14
About Our Speaker
Frank M. McCloy, R.Ph.
� Frank McCloy is the Sterile Products Supervisor at East Jefferson General Hospital
(EJGH), a 435-bed hospital in Metairie, Louisiana.
� At EJGH, he is responsible for a $7.8 million sterile products budget. He is also in
charge of the MD Anderson chemotherapy inpatient/outpatient pharmacy and
USP 797 IV compliance.
� He has 20+ years of hospital pharmacy management experience.
� He has a record of accomplishment in operations management, inventory
management, clinical program development, emergency preparedness, Joint
Commission standards, USP 797 implementation, quality improvement methods,
staff development and team building, pharmacy turnarounds/start-ups, project
management, and cost control.
4
USMP/MG1/14-0227 6/14
About Our Speaker
Donna Carbajal, RN, RRT, MBA
� Donna Carbajal is the Supervisor of Clinical Excellence and the Quality and
Organizational Effectiveness Specialist at East Jefferson General Hospital (EJGH) in
Metairie, Louisiana.
� At EJGH, her responsibilities include accountability for organizational wide
direction and facilitation of performance assessment, reassessment, development
and implementation of the Quality/Performance Improvement program in
accordance with all regulatory requirements.
� She is involved in a number of quality and organizational activities at EJGH,
including: FMEA, RCA, and performance improvement facilitation; JCAHO, CMS,
and DHH preparation, survey facilitation, & remediation; patient and system
tracers for regulatory compliance; peer review & medical staff committee support;
incident review & sentinel event determination; and leadership, medical staff,
board quality & lean performance improvement presentations and
action plans.
5
USMP/MG1/14-0227 6/14
Panelists
Frank McCloy and Donna Carbajal will be joined during the question and
answer session by their colleagues on the EJGH LEAN Management Team:
Charlotte Williams, CPT
Certified Pharmacy Technician
East Jefferson General Hospital
Metairie, Louisiana
Hai M. Nguyen, PharmD
Dept. of Pharmacy
East Jefferson General Hospital
Metairie, Louisiana
6
USMP/MG1/14-0227 6/14
Objectives
� Enhance IV room productivity and reduce IV waste
while improving medication delivery to the nursing
units.
� Demonstrate strategies resulting in a significant
decrease in medication requests.
� Identify changes in the IV drug delivery preparation
and delivery process that resulted in IV drug cost
savings.
7
USMP/MG1/14-0227 6/14
If you keep on doing what you have
always done,
You will keep on getting what you’ve
always got.
-Anonymous
8
USMP/MG1/14-0227 6/14
� Things you should know about Lean:
• Automation shouldn’t be the first answer
• Lean takes a systems approach
• Lean is team based
• Lean is a system for the absolute elimination of waste1
9
Lean
1. Thun J, et al. Int J Prod Res. 2010;48:7089-7106.
USMP/MG1/14-0227 6/14
Lean
� Based on Toyota Production System2
� Identification and elimination of WASTE in a process2
� Got its name from MIT (James Womack)3
� Improves Quality, Cost, Delivery, Safety, Morale2
� Increases process capacity2
� Reduces defects2
� Results in a stable, reliable, repeatable, predictable process2
10
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
3. Lean People. Lean Enterprise Institute. www.lean.org
USMP/MG1/14-0227 6/14
Lean
� Lean focuses on:
• Reducing the 7 wastes1
• Improving process flow2
• Increasing process speed2
11
1. Thun J, et al. Int J Prod Res. 2010;48:7089-7106.
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
USMP/MG1/14-0227 6/14
Lean
� Lean is about fixing the SYSTEM and transforming the CULTURE
� Lean is about FLOW
� Lean is about people, not just about improvement tools
� Lean is about YOUR expectations, what YOU are willing to tolerate
in terms of Quality, Cost, Delivery, Safety, Morale
� Processes rarely get better on their own
� Successful processes have rules, standards, and absolutes
� To solve a problem you have to admit you have one
� Problems need to be quantitatively defined and their corrective
action quantitatively tracked
12
USMP/MG1/14-0227 6/14
Lean: Key Elements
� Standard work2
• The process of delivering care
o Automation with a human touch
o Make problems obvious
o Immediate problem resolution
� User friendly
• Provide the patient or staff what is needed, when it’s needed, in
the quantity needed, on time, every time, 24/7/365
� Unobstructed throughput4
• Eliminating process constraints to increase throughput
13
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047
4. Oakley J. Quality. 2008;47:58-61.
USMP/MG1/14-0227 6/14
A Lean Organization
14
Standard Work User-Friendliness Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .
USMP/MG1/14-0227 6/14
A Lean Organization
15
Jidoka6
Making
Problems
Obvious
Standard Work User-Friendliness Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .
USMP/MG1/14-0227 6/14
A Lean Organization
16
Jidoka6
Making
Problems
Obvious
Standard Work User-Friendliness
Kaizen2
Continuous
Improvement
Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .
USMP/MG1/14-0227 6/14
A Lean Organization
17
Jidoka6
Making
Problems
Obvious
Standard Work User-Friendliness
Kaizen2
Continuous
Improvement
Respect2
For
People
Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .
USMP/MG1/14-0227 6/14
A Lean Organization
18
Jidoka6
Making
Problems
Obvious
Standard Work User-Friendliness
Kaizen2
Continuous
Improvement
Heijunka5
Just in Time
Respect2
For
People
Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .Pharmacy Advisor is a trademark of Baxter International Inc.
USMP/MG1/14-0227 6/14
A Lean Organization
19
Jidoka6
Making
Problems
Obvious
Value Stream Focus
Standard Work User-Friendliness
Kaizen2
Continuous
Improvement
Heijunka5
Just in Time
Respect2
For
People
Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .
USMP/MG1/14-0227 6/14
A Lean Organization
20
Jidoka6
Making
Problems
Obvious
Value Stream Focus
Lean Organization
Standard Work User-Friendliness
Kaizen2
Continuous
Improvement
Heijunka5
Just in Time
Respect2
For
People
Unobstructed Throughput
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
5. Huttmeir A, et al. Int J Production Economics. 2009;118:501-507.
6. Tamura T, et al. Int J Production Res. 2011;49:4299-4315 .
USMP/MG1/14-0227 6/14
Respect for People
� Foster a culture that enhances individual creativity
and teamwork, while honoring mutual trust and
respect between staff and management
� Acknowledge staff are the experts
� Include staff in Lean events
� Teach all staff to solve problems
21
USMP/MG1/14-0227 6/14
Unobstructed Throughput
22
4. Oakley J. Quality 2008;47:58-61.
ED ORInpatient
Unit
USMP/MG1/14-0227 6/14
Unobstructed Throughput
23
ED ORInpatient
UnitWaste Waste
4. Oakley J. Quality 2008;47:58-61.
USMP/MG1/14-0227 6/14
Unobstructed Throughput
24
ED ORInpatient
Unit
4. Oakley J. Quality 2008;47:58-61.
USMP/MG1/14-0227 6/14
Unobstructed Throughput
25
ED
OR
Inp
atie
nt
Un
it
4. Oakley J. Quality 2008;47:58-61.
USMP/MG1/14-0227 6/1426
Continuous Flow
Unobstructed Throughput
4. Oakley J. Quality 2008;47:58-61.
USMP/MG1/14-0227 6/14
Waste (Muda)2
� Waste is any activity that:
• The customer isn’t willing to pay for
• Doesn’t positively change the form, fit, or function of the
product or service (Value Added)
� Remember:
• If you don’t have time to do it right, when will you have
time to do it over?
27
2. Hintzen BL, et al. Am J Health-Sys Pharm. 2009;66:2042-2047.
USMP/MG1/14-0227 6/1428
1. Thun J, et al. Int J Prod Res. 2010;48:7089-7106.
USMP/MG1/14-0227 6/14
The Lean Process
29
Step 1
Identify Customer Value
USMP/MG1/14-0227 6/14
The Lean Process
30
Step 1
Identify Customer Value
Step 2
Map the Process
(Value Stream or
Process Map)
USMP/MG1/14-0227 6/14
The Lean Process
31
Step 1
Identify Customer Value
Step 2
Map the Process
(Value Stream or
Process Map)
Step 3
Determine capacity & customer demand
USMP/MG1/14-0227 6/14
The Lean Process
32
Step 1
Identify Customer Value
Step 2
Map the Process
(Value Stream or
Process Map)
Step 3
Determine capacity & customer demand
Step 4Identify & Eliminate
Waste
USMP/MG1/14-0227 6/14
The Lean Process
33
Step 1
Identify Customer Value
Step 2
Map the Process
(Value Stream or
Process Map)
Step 3
Determine capacity & customer demand
Step 4Identify & Eliminate
Waste
Step 5
Adjust flow to customer demand
Eliminate disruption and abnormalities
USMP/MG1/14-0227 6/14
The Lean Process
34
Step 1
Identify Customer Value
Step 2
Map the Process
(Value Stream or
Process Map)
Step 3
Determine capacity & customer demand
Step 4Identify & Eliminate
Waste
Step 5
Adjust flow to customer demand
Eliminate disruption and abnormalities
Step 6
Improve flow
and continuously
improve
Lean Organization
USMP/MG1/14-0227 6/1435
Pharmacy Kaizen
USMP/MG1/14-0227 6/14
Sense of Urgency
� Pharmacy costs as a percentage of hospital
expenditures increasing
� Waste reduction and financial stewardship of
pharmacy resources a priority
� Pharmacy leadership in a position to optimize
medication management by reducing non-value
added process steps thereby positively impacting the
hospital’s budget
36
USMP/MG1/14-0227 6/14
Problem Statement
� A month-long study
estimated annual IV
waste costs at $750,000
� Opportunities related to:
• rework
• over processing
• batching
• lack of standard work
• unnecessary motion
37
USMP/MG1/14-0227 6/14
Key Issues Identified
� Piggybacks and large volume batched in 12hr time frames
� 400 drugs/month wasted
� Expired NS and D5W 50 and 100 ml bags wasted due to lack of
use prior to expiration date when stocked in each nursing
units’ Pyxis dispensing cabinet
� Lack of point of care medication preparation resulting in
waste due to expired piggybacks not utilized within
established timeframe
38
USMP/MG1/14-0227 6/14
Key Issues Identified
� Over 200 medication requests a day from nursing due to lack
of standard work related to communication and IV delivery to
nursing units
� Lack of standardized location for delivery and pick up of
medications on nursing unit leading to duplication of IV remix
� Pharmacists are frustrated with multiple medication requests
from nursing
� Nurses are frustrated with delayed medication delivery
39
USMP/MG1/14-0227 6/14
Goals/Desired Outcomes
� Enhance IV room productivity
� Reduce IV waste while improving medication delivery to the
nursing units
� Metrics:
• Decrease medication requests by 25%
• Decrease IV waste by 30%
40
USMP/MG1/14-0227 6/14
The Team
� 4 Nurses from high usage units
� 2 Pharmacists
� 2 Pharmacy technicians
� Lean facilitator
41
USMP/MG1/14-0227 6/14
Project Preparation
� Team preparation for the project
• Team reviewed the medication request process from MD order
through delivery to nurse
• Representatives from four high volume medication request nursing
units and four pharmacy representatives were selected to participate
on team
• Facilitator conducted a 2-hr JIT education session on Lean for team
members on day 1 of the Kaizen
• Kaizen was conducted in 8-hr day intervals over 2 wks for a total of 40
hours (3 days the 1st week; 2 days the 2nd week)
• Established goals for the team
42
USMP/MG1/14-0227 6/14
Current State Medication Process
43
USMP/MG1/14-0227 6/14
Current State Supporting Documentation
44
IV Waste for 1 week Pharmacy Tech Steps
560 steps in 40 min. observation
USMP/MG1/14-0227 6/14
Current State Supporting Documentation
45
Gemba & Time Observation
USMP/MG1/14-0227 6/14
Future State Medication Process
46
USMP/MG1/14-0227 6/14
Developing the Future State
After conducting a walk
through and time
observation study of
Pharmacy Tech filling
medications, the team
used brainstorming to
develop desired future
state.
47
USMP/MG1/14-0227 6/14
Future State Supporting Documentation
� Established a timeline for implementing
recommendations and assignment/accountability for
each action item
� Gantt chart of action items with responsible party
48
USMP/MG1/14-0227 6/14
Expected Results
� Decrease medication requests by 25%
� Decrease IV waste by 30%
� Decrease return medications and associated
labor by 30%
� Improve medication storage
� Improve timeliness of medication delivery
49
USMP/MG1/14-0227 6/14
Sustainment
� Pharmacy will monitor:
• IV waste
• Medication Requests
� Nursing will monitor
• Compliance with medication storage, intake, and return
• Duplicate medication requests
50
USMP/MG1/14-0227 6/14
Reflection
� Project reflection
• Pharmacy and Nursing staff now appreciate the process steps
required to complete a medication request.
• Having Pharmacy and Nursing view each other’s processes
allowed collaboration to make changes for the better.
• Pharmacy and Nursing now have understanding of Lean
concepts and recognize waste in their processes.
� Self-reflection
• Collection of more baseline data prior to the meeting would
have benefitted the team’s productivity.
51
USMP/MG1/14-0227 6/14
Project Summary: A3
52
Background Recommentations
Current Situation
Implementation Plan
Analysis
Follow Up
Goal Results Report
Med requests delayed and/or duplicated
Why? System built to sort orders/requests by order time
Why? No sorting of new orders versus medication requests
Why? Allows duplicate med. requests.
Why? Pharmacist works queue for both new orders and medication requests by ordered time
Why? Pharmacist may not recognize med. request duplicated
IV waste high
Why? Orders changed after IV mixed
Why? IV batches are every 12hours
1) Post list of meds requiring med requests, longer mix times, and shorter expiration dates by nursing unit pyxis
2) Standardize nursing unit medication bins (one in and one out bin) located in pyxis room (exception: ICU central location but multiple
bins set up)
3) Paint 30 tube system cannisters blue to alert nursing to return to Pharm immediately
4) Implement hourly Main Pharm Tech rounding of IV Meds needing to be tubed to prevent delay
5) Implement IV Pharm Tech coordination w ith Main Pharm Tech to deliver NICU p.o. meds w hen NICU IV meds are delivered.
6) Implement sorting box in IV Med room to allow Pharm to track pending requests by time due.
7) Create tube system dow ntime code f or Pharmacy to alert Charge Nurses of 2 hr rounding implemented
8) Purchase Cardizem connector to allow nurses to mix medication on unit (reduce med. request and expired meds.)
9) Reposition 2E scanner closer to unit secretary w orkstation
10) Purchase IV piggyback (D5W, N/S 50 &100cc bags) to individually w rapped and move to nursing unit stock. Set up Par levels.
11) Decrease IV bulk and piggyback batch runs from 12 hr to 2 hour intervals to reduce IV w aste.
12) Create medication request queue for Pharm. Techs to expedite response to nsg med. req.
13) Install w ireless phones for Pharmacy Techs
14) Meet w ith Nsg Directors to agree on secure non-emergent bulk meds storage (locked bedside table draw )
15) Educate Nsg and Pharmacy on changes (use education flyer, EGG, unit meetings)
1) Round on nursing units & Pharmacy to review impact and compliance with changes.
2) Collect established metrics (below) to assess impact of changes and long term gains.
A 2009 week long study revealed we are wasting $750,000 in duplicate/expired/wasted IV medications. In addition, approx. 600 medication
requests per day are processed by the Pharmacists. Many requests are duplicates which creates delays leading to frustration for both the
nursing and pharmacy.
% CompDec Jan FebDescription#
3115 147 2821 4 15
75%Pasqua / ITMed. Req. Queue for Pharm Tech7
25%Pasqua/Nsg DirMeet /w Nsg re: locked bedside table 2.15.116
25%Scanlon / ITReposition 2E Scanner 2.15.115
25%McCloy/RadtkeIV Piggybacks as Nsg Floor Stock 2.4.114
100%PasquaCadizem connector 1.20.113
75%McCloy/TorresReduce IV batches to 2 hr intervals 2.15.112
100%RauschWireless phones for Pharm Tech 12.10.101
Who
Pharm Tech560 steps in 40 min. observation
IV Waste for 1 week
Standard work observation
Establishing standard work for nsg station meds in / out
Visual Signals: Blue tubes identifies Pharmacy tubes to be returned to Pharm
immediately to expedite delivery of meds to
nurses
USMP/MG1/14-0227 6/14
Improvements
� 400 most commonly used
drugs relocated closer to the
pharmacy technician
• Reduced steps and improved
fill time
� Batches reduced from 12 to
3 hours for all piggybacks
and LVPs
• Created more nimble
response to changes in orders
and patient discharges
• Resulted in reduced IV waste
53
560 steps in 40 minutes
USMP/MG1/14-0227 6/14
Improvements
� Quick connect device placed on nursing units’ supply
cart (Diltiazem, Vancomycin 1 g and Azithromycin) for
small IV infusions
• Rework reduction for pharmacists by eliminating the
duplicate requests from nursing to fill an order already
processed
• Nursing administration delays reduced due to minimization
of searching for a piggyback or requesting again from
pharmacy
54
USMP/MG1/14-0227 6/14
Improvements
� NS and D5W 50 & 100 ml bags stocked on nursing
supply cart as individually wrapped bags
• Added longer shelf life reducing waste due to expiration
of unwrapped bags prior to use
� Medication request queue created for
Pharmacy Tech
• Reduced redundant requests leading to potential
duplication by Pharmacist
• Allowed quicker response to nursing request
• Reduced workload for pharmacist
55
USMP/MG1/14-0227 6/14
Improvements
� Standardized pharmacy delivery and pick up
locations on nursing units
• Allowed quicker identification of delivered drugs
• Reduced duplicate medication requests
56
USMP/MG1/14-0227 6/14
Improvements
� Thirty tubes from tube
system painted blue
• Visual cue
• Enhanced prompt return
to Pharmacy
57
Visual Signals: Blue tube identifies
Pharmacy tubes to be returned to
Pharmacy immediately to expedite delivery
of meds to nurses.
USMP/MG1/14-0227 6/14
Improvements Continued Post Kaizen
� To reduce IV bags and tubing waste, a new process
was established for nurses to push IV ABX instead of
using an IV pump.
� Sterile water needed as a nursing unit stock supply
for IV medication dilution.
58
USMP/MG1/14-0227 6/14
Kanban & Push vs Pull1
59
� Kanban literally means
“visual card”
� Kanban is a card,
labeled container,
computer order, or
other device used to
signal that more
products are needed
� It creates a pull rather
than a push system
� It uses Just in Time
ordering to minimize
stock outs
1. Thun J, et al. Int J Prod Res. 2010;48:7089-7106
USMP/MG1/14-0227 6/14
Current State
� Using IV piggyback and
IV pump sets to deliver
antibiotics in IV
piggyback bags
� Wasting IV piggyback
antibiotics due to delay
in administration or
delay in getting d/c to
pharmacy
60
Waste
USMP/MG1/14-0227 6/14
Future State
� RNs now pushing IV
medications, when
appropriate, eliminating
wasted IV bags and tubing.
� Sterile water now stocked on
each nurses station in a
Kanban system to prevent
stock outs. Nurses put
Kanban card in pharmacy
return box for restocking.
61
USMP/MG1/14-0227 6/14
Two Bin Kanban
� Two bin Kanban
• Calculate par levels, reorder quantity, & reorder time
• Stock enough supplies to meet demand
� Standard Work
• Pull supplies from top bin first
• When top bin empty, replace with bottom bin
• Place Kanban card in Pharmacy return box
• Pharmacy tech picks up Kanban card & restocks
62
USMP/MG1/14-0227 6/14
Responsibility
63
Action Due Date % Complete Person
Restocking
Kanban
Daily 100% Pharm.
Tech
Monitoring
Compliance
Biweekly 100% Pharm IV
Supervisor
USMP/MG1/14-0227 6/14
Results
� March 2011:
• 71% reduction in medication requests and a 41% reduction
in IV waste were realized
� Since then:
• IV waste decreased from $62,500/month to $4000/month,
a savings of $58,500/month
• Mainly attributed to the reduction in IV batches from
twelve to three hours
• Utilization of quick connect adaptors allowing nurses
access to medications using just in time philosophy
64
USMP/MG1/14-0227 6/14
Results
� The shared understanding of the process between
pharmacy and nursing has led to:
• Improved communication
• Teamwork as departmental silos are broken down to
improve the medication process flow
65
USMP/MG1/14-0227 6/14
Results
� Annualized 2011 IV waste
• $48,000/year
• 94% improvement when compared to the 2008 IV waste of
$750,000/year:
Annual savings of $702,000
66
USMP/MG1/14-0227 6/14
We Welcome Your Questions
� You can submit questions throughout the webinar
using the form on your screen
� If you experience any technical issues during the
webinar, please use the help button shown on your
screen
� The views and opinions expressed during the
question and answer session are those of the
individual presenters and should not be attributed to
Baxter
67
USMP/MG1/14-0227 6/14
References
1. Thun J, Druke M, Grubner A. Empowering Kanban through TPS-principles–an
empirical analysis of the Toyota Production System. Int J Prod Res. 2010;48:7089-
7106.
2. Hintzen BL, Knoer SJ, Van Dyke CJ, Milavitz BS. Effect of lean process improvement
techniques on a university hospital inpatient pharmacy. Am J Health-Sys Pharm.
2009;66:2042-2047.
3. Lean people. Lean Enterprise Institute. Available at:
www.lean.org/WhoWeAre/LeanPerson.cfm?LeanPersonId=1. Accessed May 15,
2012.
4. Oakley J. Increasing throughput with lean concepts. Quality. 2008;47:58-61.
5. Huttmeir A, de Treville S, van Ackere A, Monnier L, Prenninger J. Trading off between
heijunka and just-in-sequence. Int J Production Economics. 2009;118:501-507.
6. Tamura T, Okumura T, Singh Dhakar T, Ohno K. Optimal production sequencing
problem to minimise line stoppage time in a mixed-model assembly
line. Int J Prod Res. 2011;49:4299-4315.
68