Crash course

ANY given episode of a television medical drama is likely to feature a patient going into cardiac arrest. As the victim thrashes around, a telegenic doctor summons a posse of helpers, who start zapping the patient, compressing his chest or administering adrenalin jabs until the heart starts ticking again.

On TV these efforts almost always succeed, spectacularly and immediately. The real world, sadly, is crueller: doctors manage to restart only about half of the hearts that stop in a hospital, and only about a sixth of patients will go on to survive long enough to be discharged. One of the toughest decisions faced by hospital staff is how long to keep trying, and when to give up on a particular patient as a lost cause.