Fifteen years ago, Israeli scientists published a study in which engineers observed patient care in ICUs for twenty-four-hour stretches. They found that the average patient required 178 individual actions per day, ranging from administering a drug to suctioning the lungs, and every one of them posed risks. Remarkably, the nurses and doctors were observed to make an error in just 1 percent of these actions—but that still amounted to an average of two errors a day with every patient.