Impact of LEAN principles in the Emergency Department

March 2013

Impact of LEAN principles in the Emergency Department

Search Strategy: Pubmed search for “Emergency department” AND “LEAN” and (“patient flow” or “throughput” or “patient satisfaction” or “quality improvement”) ( The search results in 16 articles, of which 4 are chosen for being the most relevant.

As you are about to start a Friday evening shift in EM 1, you are greeted by the all too familiar sights and sounds of an overcrowded emergency department. There are 8 boarding psychiatric patients awaiting transfers, a line of EMS arrivals attempting to navigate their way into the department, a waiting room with 50 patients, three patients sitting in the hallway, four patients in the “MRI Room” and a wandering patient that keeps offering lottery numbers to anyone who will listen. After taking a deep breath, you sit down to prepare for sign out. Before you are even able to write down the first patient name, your charge nurse approaches and asks if any patients can go to observation, the dispo lounge, the hallway, a closet or anywhere else that is not an examination room.

After discussing the lack of inpatient beds with the departing team, you begin to wonder aloud if there are any strategies that could be adopted that would improve the patient flow through the emergency department. You remember seeing an oral presentation at SAEM last year that discussed the use of LEAN principles in the emergency department and rhetorically ask, “Could a process improvement plan using LEAN principles improve care in our emergency department?” As soon as you mention LEAN, the off-going attending immediately jumps up and yells, “they used LEAN principles here already, and all we have to show for it are patients in the hallway and an empty dispo lounge!” Suddenly Brian “The ninja” Cohn drops from the ceiling and says, “This sounds like a case for EBM!”

PICO Question

Population: US Emergency Departments

Intervention: Process improvements using LEAN principles

Comparison: None

Outcome: Improved patient flow, throughput, patient satisfaction, or quality improvement.


Article 1: Murrell KL, Offerman SR, Kauffman MB. Applying lean: implementation of a rapid triage and treatment system. West J Emerg Med. 2011 May;12(2):184-91.

Article 2: Dickson EW, Singh S, Cheung DS, Wyatt CC, Nugent AS. Application of lean manufacturing techniques in the Emergency Department. J Emerg Med. 2009 Aug;37(2): 177-82.

Article 3: Ng D, Vail G, Thomas S, Schmidt N. Applying the Lean principles of the Toyota Production System to reduce wait times in the emergency department. CJEM. 2010 Jan;12(1):50-7.

Article 4: Dickson EW, Anguelov Z, Vetterick D, Eller A, Singh S. Use of lean in the emergency department: a case series of 4 hospitals. Ann Emerg Med. 2009 Oct;54(4): 504-10.

Bottom Line

What is Lean?

Lean manufacturing is a practice that originated in the automotive industry, specifically the Toyota corporation, which focuses on minimizing waste, increasing efficiency, and promoting flow through the system. Lean attempts to reduce waste by eliminating those aspects of the process which do not add “value” to the end product. Value, in this context, is defined as any process or procedure that a customer would be willing to pay for. In recent years, the healthcare industry has attempted to adopt Lean process improvements in order to increase efficiency, decrease overcrowding, and improve patient flow through the healthcare system. This practice has been used in most aspects of healthcare, including the emergency department.

The typical Lean improvement begins with a kaizen event, which classically involves three components. The first component focuses on defining the current process, by creating a value stream map (see Figure 1) which details the progress of the product (or patient) through the system from start to finish. The second component consists of identifying waste in the current system and detailing methods of eliminating waste and maximizing value to create a future (or ideal) state value stream map. The third step consists of testing ideas to attempt to move from the current state to the future state. A proper Lean process improvement is careful to involve frontline workers in all components of the process, with appropriate support and buy-in from leadership personnel.

Should Lean be applied to healthcare?

Several concerns have been raised regarding the application of Lean principles to Emergency Department (ED) care. Foremost is the concern that patients are not automobiles, and improvements in auto manufacturing do not necessarily apply to the care of the ill. An automotive factory builds cars; EDs do not build people. Some claim that drawing comparisons between the automotive and healthcare industries is like comparing apples to oranges; I would argue it is more akin to comparing apples to triangles. There is simply no relation between the two.

A second major concern is the difficulty in defining “value” and “waste” in an industry with multiple stakeholders, including patients, physicians, hospital administration, insurance providers, and society (see editorial by Porter 2010). When surveyed, performance interests have been shown not to be homogeneous among various stakeholders in emergency department care (Tregunno 2004). What the patient may define as value (i.e. obtaining an MRI to determine the cause of back pain), the physician may deem unnecessary, insurance may be unwilling to pay for, and society may have to consume the cost of. Many studies on Lean in the ED define value relative to time, attempting to show decreases in length of stay (LOS); while it may seem to benefit the hospital, a shorter stay with an incorrect diagnosis and inappropriate treatment would not have greater “value” in the eyes of the patient, and in the long run may harm the hospital by leading to increased readmissions.

What did the studies show?

The included studies suffered from significant methodological flaws, which makes the interpretation of their results difficult. These were all retrospective observational studies, however they failed to provide detailed chart review methods (Gilbert 1996, Worster 2004). Statistically, the studies reported mean values for time-based outcomes (length of stay, time to see a doctor, arrival to room time) rather than median values, despite the fact that these values are not normally distributed, and should instead be reported as medians. Only one study reported measures of precision, incorrectly using p-values for the outcomes. All of the studies utilized before-and-after study designs and would likely be biased by the Hawthorne effect. These factors make it difficult to draw any conclusions regarding the benefits of Lean improvements from these studies.

What was our consensus?

Our group felt that while there was little evidence to support Lean process improvements in the ED, there as also no evidence to refute its benefit. Many aspects of Lean are appealing, and were felt to be important to any process improvement, including the emphasis of frontline workers in identifying problem areas, the importance of staff buy-in when implementing changes, and the importance of having support from leadership personnel. However, it was not felt by all that a true “Lean” process change was needed for these elements to be used.