By BOB WACHTER, MD 
Several years ago, I spoke at Baylor College of Medicine in Houston, where Michael DeBakey, the legendary heart surgeon, was master of the universe for nearly half a century. I heard lots of DeBakey stories during my visit, but one in particular really stuck with me. “A few years back,” someone told me in a voice of hushed reverence usually reserved for descriptions of flawless beach days and single malt scotch, “he performed 16 open heart operations in a single day.” This was clearly intended to impress, but all I could think was, “Boy, I wouldn’t want to be patient #16.”
Lacking any information to help us understand when fatigue trumps even legendary prowess, such monumental tales of endurance can take on Man of Steel proportions. But a recent study in the Journal of the American College of Radiology may be the start of efforts to trim Superman’s cape.
Researchers from the Universities of Arizona and Iowa observed radiologists as they reviewed a handpicked set of 60 bone x-rays, half with fractures and half without. As their eight-hour workdays wore on, the radiologists’ accuracy fell by an average of 4%, with equal drops in sensitivity (missing a true fracture) and specificity (incorrectly calling a fracture when there was none). The degradation in performance was statistically significant.
