The Razor's Edge By Neal E. Flomenbaum, MD, Editor-in-Chief

Years ago, when asked to describe the difference between internal medicine and emergency medicine, I said that it was a little bit like the difference between Occam’s razor and Gillette’s Trac II. Let me explain.

William of Occam, the 14th-century English logician, is credited with advancing the idea that “plurality should not be posited without necessity.” Also known as the “Law of Parsimony,” it was adapted to the practice of medicine some 500 years later by William Osler, who postulated (loosely) that “a single explanation that can account for all of a patient’s signs and symptoms usually is correct.” The 19th-century diseases that best exemplified this principle were tuberculosis, bacterial endocarditis, and diabetes, none of which could be cured or effectively treated at that time.

The deductive reasoning required to identify the underlying cause of a patient’s problems is one of the most intellectually stimulating exercises associated with the practice of internal medicine. (If you have never seen a master internist arrive at a correct diagnosis by reasoning based on the history, physical examination, and laboratory evidence, you may want to watch the next episode of “House” on television.)

Enter emergency medicine, where time and extensive diagnostic testing are severely limited. It seems obvious that deductive reasoning skills would be valuable, if not essential, to quickly diagnose and treat serious acute or life-threatening illnesses.

But, with the notable exception of diagnosing toxicologic syndromes, it never really turned out that way. On the contrary, it seems there is hardly ever a single explanation for anything. A sign or symptom, such as loss of consciousness, frequently is the result of two or more etiologies—for example, a depressant drug precipitating trauma, which in turn results in a subdural hematoma. The unfortunate emergency physician who identifies only one of several causes and stops there will inevitably hear later from an esteemed medical or (worse) pathology colleague about the diagnoses that were missed.

In 1971, Gillette introduced a product that seemed to serve as a better paradigm than Occam’s razor for our newly evolving specialty—the Trac II. This razor, with its tightly spaced twin blades, promised the closest shave ever: the hairs that the first blade missed would surely be sliced off by the second. With this paradigm in mind, the clinician can avoid the risk of (with apologies to the Lovin’ Spoonful) “picking up on one and leaving the other behind.”

Medical decision-making is the subject of the best-seller How Doctors Think, by Jerome Groopman, MD, chair of medicine at Harvard Medical School. In one chapter, Groopman examines the problems faced by emergency physicians who must make decisions under time constraints and without the benefits of knowing the patient for more than a few minutes or having sufficient information.
To prevent the diagnostic errors resulting from thinking inside the box—committing prematurely to a wrong or inadequate diagnosis—Groopman cites the example of an endocrinologist who, even when dealing with a patient with an apparently obvious diagnosis, always asks, “What else could this be?” A version of this question that has served many emergency physicians well over the years is “What is the worst thing this patient could have?”

The skilled clinician must be able to apply whichever paradigm is most appropriate for a particular patient. Pattern and syndrome recognition must immediately come to mind when applicable, while the possibility of more than one cause should not be overlooked just because Osler may have suggested otherwise. Added to this decision-making responsibility must be some sense of how far to go in pursuing different diagnoses in the emergency department without breaking the bank or overtaxing limited resources.

These days Gillette is proudly promoting its newest razor, a five-bladed “fusion” model promising the closest shave ever. In the critical area of diagnostic decision-making, I believe our specialty can claim to have made at least as much progress as Gillette.

Emerg Med 39(06):8, 2007