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Tom LAcey

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Health Care

Lean Six Sigma in a Health Care Environment

Cutting clinical contamination

Published: Wednesday, October 14, 2009 - 05:00

In 2005, according to a BBC News report at the time, operating rooms all over the United Kingdom were thrown into chaos and operations canceled due to broken, missing, or dirty surgical instruments. The Royal College of Surgeons called for a national audit of decontamination units, following a report in the April 2008 Clinical Services Journal on surgery being canceled due to instruments being returned with visible blood and bone contamination. A report from the United Kingdom’s National Health Service (NHS) decontamination program revealed that 1,765 operations were called off at the last minute in 2005 and 2006 because of instrument problems.

This was a high-profile problem for the NHS and was taken very seriously, particularly because an audit eight years ago highlighted the need to upgrade and modernize decontamination facilities. Many hospitals have entered into contracts with commercial sterilization services, while others, such as the New Royal Infirmary in Edinburgh, have an in-house unit.

The HSDU at the New Royal Infirmary before (left) and after (right) Six Sigma process improvement


The hospital sterilization and disinfection unit (HSDU) at the New Royal Infirmary is one of the busiest in the United Kingdom, processing more than 7 million reusable instruments each year. It employs more than 100 staff operating 24 hours per day, 365 days per year, and has been in operation since 2002.

The process is, in theory, straightforward. Surgical devices and instruments are returned from 30 sites across Lothian, stripped, washed, disinfected, reassembled in the clean room, sterilized, and returned to the surgeries. However, even a small speck on an instrument may lead to rejection by a surgeon who is concerned about the risk it may pose to patients. In 2005, the number of incidents of contaminated trays being returned to the HSDU reached chronic proportions. The level of risk was measured using failure mode and effects analysis and more advanced Bayesian analysis models, and was assessed as high. Although the staff at the HSDU were working to improve the situation, they were essentially fire-fighting, working overtime and reworking trays as fast as possible. The problem just seemed to continue.

A proposal was put forward to resolve this problem using Six Sigma. There were many examples of where the same techniques had been successfully employed in industry and there was no reason to assume they would not work in the NHS. The advantage that Six Sigma had over other improvement tools was the emphasis on ensuring senior management commitment up front, allowing maximum staff participation, and statistical analysis where required. The plan was put forward to the director of operations, Jane Todd, and the HSDU manager, Alexa Pilch. Their response was immediate and positive—although Six Sigma had never been used in the unit, events seemed to require a new approach to problem resolution.


There were a number of factors to consider:

Reducing the risk—How could we bring down the number of clinical risks?

Demand pressure—Typically the HSDU could handle 350 trays per day, but frequently there were in excess of 850 trays in the unit. How could the unit afford to deal with contamination issues when it was under such pressure for throughput?

Conventional wisdom—Management felt that there was little chance of taking time out to indulge in a new "fad." How could this mind set be changed?

Budget—There were no funds available to tackle this problem. How could it be overcome utilizing only the existing (overstretched) resources?


Six key success factors were identified up front:

  1. Senior management involvement from the start
  2. Get the right people on board
  3. Set clear achievable objectives
  4. Keep it simple
  5. Determination to achieve the objectives
  6. To resolve the problem, be positive


Using Six Sigma

Six Sigma is a management philosophy aimed at improving effectiveness and efficiency. Other quality initiatives focus on quality tools, but Six Sigma relies on the active involvement of all staff and especially management. This focus on staff involvement was the key factor in ensuring a successful outcome for the project.

A specific challenge with this project was how to achieve success using the key Six Sigma technique of define, measure, analyze, improve, control (DMAIC) in the HSDU, where no continuous improvement approaches had previously been used. The decision was taken early on to keep the project as simple as possible. The key practical stages are outlined below.

Setting the objectives

Setting objectives was a crucial first step to achieving success; projects so often fail because they are poorly defined, the scope is not manageable, or the targets are too ambitious. Several weeks were allocated to this aspect, involving the 16 key operating rooms and senior management at each stage. Quality surveys were conducted using Likert scaling and project targets were discussed and agreed with senior management before the initiative began. These are outlined below:

  • Clinical risk reports—decrease from six to zero per month within a year
  • Contamination complaints—decrease from 118 to four per month within a year
  • Rewash (rework) activity—decrease from 250 to 50 per month within a year
  • Process sigma—achieve Six Sigma status within two years


Selecting the team

Selecting the right team was identified as the second critical step. First, a project coordinator was appointed, Chris Hodkinson, who had been working in the HSDU for several years and had first-hand knowledge of the problem and the processes. Although he had no experience of quality techniques, he possessed the skill set needed for the project. The next challenge was to allow Hodkinson to stop working in the process department and focus solely on driving the project. Again, senior management commitment was crucial as there was a risk in taking people away from processing.

The remaining team members were carefully selected from each shift to ensure good coverage of the 24-hour operations. They then worked on the project as required.

Team training

Intensive training in the basics of DMAIC was undertaken over a period of two months. Again training was on a “need-to-know” basis, as the intention was not to create a set of Six Sigma experts. Basic quality tools covered how to define the problem: process mapping, data collection, survey techniques, fault tree, Pareto charting, simple control charting, and sequential sampling.

Process mapping (see image below) was particularly critical to the success of the project. Detailed process maps were created and used to identify the potential sources of the contamination problems. It was also a superb method for getting maximum participation from the team members and focused problem identification.

Example of process mapping

Stakeholder analysis

A stakeholder was defined as anyone affected by the solutions arising as a result of the project. Stakeholder groups included operating rooms, senior management, HSDU management, and staff were surveyed and each group's commitment to the project was assessed. The key results from this analysis allowed us to assess the level of senior management buy-in and identify where the main resistance would come from early on. This allowed us to greatly increase our chances of success.

The majority of the stakeholders were very much in favor of the project quality surveys. Likert scaling with nonparametric analysis to ensure statistically significant findings was conducted to confirm their commitment to its success.

One of the major concerns highlighted during the stakeholder analysis was valuable time and resources being taken away from the “real” work of getting trays out of the HSDU. However, most staff were fully supportive of the project, which was confirmed by formal and informal meetings. They were very receptive to any improvements that would make their life easier and reduce daily stress levels, but the importance of support from senior management simply cannot be overemphasized.


The following table demonstrates the results achieved in the unit. Not all of our targets were achieved within the time frame specified.

Key targets and results

(to be achieved by Feb 2007)

Feb 2006

Feb 2007

March 2008

Clinical risk events
(Target: 0)




Contamination complaints
(Target: 4)




(Target: 50)




Process sigma
(Target: 6 by 2008)




The key target was the reduction of risk due to contaminated trays, and this was achieved. With hindsight, secondary targets were too ambitious but even so were eventually achieved. Future projects will take into account the need to set realistic secondary targets in the unit, but the graph below clearly indicates the positive gains that the unit achieved. The old “chronic” level of contamination was overcome and, more importantly, maintained.

Number of contaminated trays per month

The future

Based on the success achieved in this project, the director of operations, Jane Todd, has allowed further training and implementation of lean methodologies. The next areas to be addressed included missing equipment and devices requiring repair.

A kaizen approach initially involving 12 staff was used and training in February 2008 involving new staff members was well received.


About The Author

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Tom LAcey

Tom Lacey is the head of quality at the New Royal Infirmary HSDU in Edinburgh.