Someone collapses, a hero starts CPR, a few firm pushes and rescue breaths, and the person coughs back to life and sits up, good as new. On television it works most of the time, so most people assume CPR usually revives someone, quickly and completely.
CPR saves lives, but it does not usually bring people back the way TV shows it. Studies of medical dramas found characters survive CPR around two-thirds of the time, often springing back without lasting harm. Reality is far harsher: for cardiac arrests that happen out of hospital, only roughly one in ten people survive to leave hospital, and even in hospital the figure is well under half, with some survivors facing serious complications. CPR's real job is to keep oxygenated blood moving to the brain and buy time until a defibrillator or advanced care can address the underlying problem; it is a bridge, not a cure, and it rarely restarts the heart by itself. None of this is a reason not to do CPR, because doing it dramatically improves the odds compared with doing nothing, and bystander CPR genuinely saves lives. But the expectation that it almost always works, set by decades of television, is wrong, and it can make the real outcomes harder for families to face.