Do you "go down three times" before drowning?
Several times I've heard people say that a drowning victim actually drowned when he "went down for the third time." I know I've seen this same situation depicted in animated cartoons, too. Is there any truth to the belief that people drown once they've gone down for the third time? And how could scientists study something like this without letting people drown?
Scientists study drowning the same way they study everything else--by administering slow death to kitty cats, guinea pigs, and whatever else is handy. (They do not, incidentally, watch the cartoons, which are not normally regarded as a source of reliable medical insight.) At any rate, it's not true that you go down three times before drowning. In fact, in some cases, notably those involving alcohol (thought to play a role in 25 percent or more of adult drownings), the victim does not struggle at all, and consequently goes down just once. However, it's true that in most cases of drowning there is a fairly predictable predeath scenario, to wit: (1) panic, violent struggle; (2) attempts at swimming; (3) apnea, or breath-holding, during which time the victim often swallows large amounts of water; (4) vomiting, gasping, and inhaling (as opposed to swallowing) of water; (5) convulsions; and finally (6) death. To the extent that "going down three times" is a crude folk attempt to describe the preceding process, there's a germ of truth in it. But it's not literally accurate.
Interestingly, there are several distinct ways of drowning. In perhaps 10 percent of all cases, the victim does not actually breathe in any water, but instead dies of asphyxiation due to laryngospasm, or reflex closing of the vocal cords. (This may be what causes drunks to drown, although others suggest the cause is actually sudden heart stoppage). There's also a big difference between drowning in fresh water and drowning in salt water. In a freshwater drowning, the inhaled water is quickly absorbed out of the lungs and into the bloodstream. Unfortunately, the water washes away the wetting agent (the surfactant) in the lung air sacs (the alveoli) that helps keeps the sacs inflated. As a consequence, the air sacs collapse, oxygen can't get into the bloodstream, and the victim expires. In a saltwater drowning, on the other hand, the inhaled salt water draws blood plasma out of the bloodstream and into the lungs. The subsequent fluid buildup in the air sacs prevents oxygen from reaching the blood, resulting in death.
A couple other points while we're on the subject. Hypoxia, or tissue oxygen starvation, can persist long after you get a near-drowning victim out of the water--in some cases for days or weeks. So don't assume the danger is over just because the victim looks like he's recovering. Second, hypoxia is worse with salt water than with fresh. Saltwater near-drowning victims are more resistant to certain forms of treatment than freshwater victims.
In short, if you're going to get in trouble in the water, have the sense to do it in the fresh stuff, not the ocean.