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Historically, the approach to medical errors had been to blame the provider delivering care to the patient, the one acting at what is sometimes called the “sharp end” of care: the surgeon performing the transplant operation or the internist working up a patient's chest pain, the nurse hanging the intravenous medication bag, or the pharmacist preparing the chemotherapy. Over the last two decades, we have recognized that this approach overlooks the fact that most errors are committed unintentionally by hardworking, well-trained individuals, and such errors are unlikely to be prevented by simply admonishing people to be more careful, or worse, by shaming, firing, or suing them.

The current approach to patient safety replaces “the blame and shame game” with systems thinking—a paradigm that acknowledges the human condition—namely, that humans err—and concludes that safety depends on creating systems that anticipate errors and either prevent or catch them before they cause harm. While such an approach has long been the cornerstone of safety improvements in other high-risk industries, systems thinking had been ignored in medicine until more recently.

British psychologist James Reason's “Swiss cheese model” of organizational accidents has been widely embraced as a mental model for system safety1,2 (Figure 2-1). This model, drawn from innumerable accident investigations in fields such as commercial aviation and nuclear power, emphasizes that in complex organizations, a single “sharp-end” (the person in the control booth in the nuclear plant, the surgeon making the incision) error is rarely enough to cause harm. Instead, such errors must penetrate multiple incomplete layers of protection (“layers of Swiss cheese”) to cause a devastating result. Reason's model highlights the need to focus less on the (futile) goal of trying to perfect human behavior and suggests that greater effort be directed at shrinking the holes in the Swiss cheese (sometimes referred to as latent errors) by creating multiple overlapping layers of protection to decrease the probability that the holes will ever align and allow an error to result in harm.

Figure 2-1

James Reason's Swiss cheese model of organizational accidents. The analysis is of “The Wrong Patient” case in Chapter 15. (Reproduced with permission from Reason JT. Human Error. New York, NY: Cambridge University Press; 1990. Copyright © 1990 Cambridge University Press.)

The Swiss cheese model emphasizes that analyses of medical errors need to focus on their “root causes”—not just the smoking gun, sharp-end error, but all the underlying conditions that made an error possible (or, in some situations, inevitable) (Chapter 14). A number of investigators have developed schema for categorizing the root causes of errors; the most widely used, by Charles Vincent, is shown in Table 2-1.3,4 The schema explicitly forces those ...

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