When is Lean too Lean?

“Lean” manufacturing or management is a popular program to improve the quality and productivity of laboratory operations, including cytology operations.  According to Wikipedia, “Lean,” is a production practice that considers the expenditure of resources for any goal other than the creation of value for the end customer to be wasteful, and thus a target for elimination…  Essentially, lean is centered on preserving value with less work. Lean manufacturing is a management philosophy derived mostly from the Toyota Production System (TPS).” This approach has been used to improve the performance of laboratories around the world.

While I think this approach is quite valuable for managing laboratories, every time I hear someone talk about it I am immediately reminded of Charles Perrow’s classic text, “Normal Accidents.”  In this text he reviews how and why accidents occur in high risk situations, including the airline and nuclear power industries.  In brief, he distinguishes between two different approaches to management, “tightly coupled” and “loosely coupled.”  In a tightly coupled scenario, the productivity is very high and there is no waste because the process has been streamlined to a very high degree.  In a loosely coupled scenario, things are not as streamlined, there is more redundancy, and there is simply more time and manpower to make sure a task gets done properly.  His essential point is that as long as humans are part of a process, there will always be mistakes.  In a loosely coupled process, there is time and opportunity for a human to catch a mistake before an accident occurs; while in a highly coupled process, there is less redundancy, and it is much more likely that a human mistake will lead to an accident.  His review of the history of accidents in high risk occupations repeatedly shows that accidents tend to occur more often and be more severe in a tightly coupled situation.  Not surprisingly, he suggests that we should not make industries where the consequences of an accident are severe tightly coupled organizations.

At first glance “Lean” seems to be all about creating a tightly coupled scenario.  The process is streamlined as much as possible to eliminate waste and redundancy and to improve productivity.  But this is not quite right.  Although I am no expert on “Lean,” in my experience, managers can implement “Lean” in two very different ways.  In the first way the process is streamlined to eliminate as many steps as possible, because each step is another chance for a human to make a mistake.  The less opportunities given to humans to err, the fewer errors there will be.  This is “Lean” the way I think it was meant to be implemented.  Obviously the other way to implement “Lean” is to eliminate the redundancy in a system.  While I am not sure this is what the originators of “Lean” intended, it certainly is a way in which it is in fact implemented.  While this will improve productivity, it will not reduce the overall chance of error since it does not reduce the opportunities for error.  Instead, it simply eliminates any chance to detect and correct any errors that might be in the system.  And since no one is looking for errors, it is not surprising that no one is finding any, and it is all too easy for everyone to think that the system is working just fine.

As we all head into the future of medical care, there will be more and more pressure to increase the productivity of every laboratory.  In this setting, it will be important for cytologists to recognize that we too work in a high risk environment where errors can have grave consequences.  We need to be ever vigilant that there are two very different approaches to streamlining a laboratory, and the impact on errors of these approaches is very different.  Management may not always be able to distinguish between the two results simply because one may not always look for errors.  Eliminating unnecessary steps to reduce the opportunity for humans to err is always beneficial, eliminating redundancy is not.  As my friends who do not do cytology always ask me when I complain about how hard my job can be, “why don’t you just look at every case twice?”  I have yet to come up with a very good answer to the question.

Andrew A. Renshaw, MD