When I was teaching Red Cross Lifeguarding, and its predecessor, the more general Lifesaving course, I added a description of the full drowning process so the students would be clear about just what we were trying to prevent.
The official definition of drowning is suffocation by water. Contrary to popular belief (and as depicted in this photo) drowning is often quick, deceptively calm, and silent. Lifeguards must be taught to recognize the “instinctive drowning response,” the automatic response of a victim in immediate danger of drowning. It is not one of screaming and waving. The victim cannot call for help because they cannot breathe. They are not waving their arms because their instinct is to push down on the water with both hands and tilt their head back to raise their mouth above the surface. Rising above the surface for a gulp of air occupies all of their thinking, so they cannot reach out for a tube or kick their feet to move toward a pool ladder only a few feet away. They are in total panic mode, but it is unseen. They appear relaxed, calmly bobbing and playing. The absence of simple actions of self-rescue seem to an untrained observer as conformation that all is well. Many a parent has watched their child drown without even realizing an emergency was occurring. Even other swimmers within reach are unaware of the tragedy in progress and do nothing.
Learning to swim is the best way to prevent drowning. Just developing rudimentary skills of moving in the water will help prevent the incapacitating panic of drowning. Under the Red Cross system, a person becomes qualified to teach swimming by becoming a Water Safety Instructor since safety is the purpose of learning to swim.
When I was lifeguarding a local indoor pool, a frequent swimmer was a young man normally bound to a wheelchair by cerebral palsy. Swimming was a welcome release for him. Having little muscle control, he would thrash wildly in the water, and occasionally a visitor would scream at me, “Do something. He’s drowning!” No, he’s not. He was making forward progress. His head was constantly above the surface. He was showing none of the signs of the instinctive drowning response. The visitor was judging the situation by the common misconceptions of what drowning looks like. I had to calm them down.
When a person is deprived of oxygen, they loose consciousness in about two minutes. Brain cells are particularly dependent on oxygen and they begin dying in about 4 minutes. Within 10 minutes they are generally all dead. Other cells are more resistant. Muscle cells, such as those in the heart, may live for 30 minutes without oxygen. This means a rescued, unconscious victim may be revived, the heart restarted and breathing restored, but they will forever have a varying degree of permanent brain damage.
When a drowning victim loses consciousness, 80% of the time the throat muscles relax and water pours into the lungs. Without the buoyancy of the inflated lungs, the body sinks, not gracefully as in the movies, but head first since the head is the heaviest part. In the other 20%, the throat will stay closed, but it is not known what causes the difference.
The body is filled with various strains of bacteria whose growth is held in check by the normal body mechanisms. Once these mechanisms stop, they are free to grow unimpeded. The body is now a chunk of rotting meat, releasing gases of putrefaction. These gases are trapped under the skin and can bloat the body beyond recognition. The gases restore buoyancy and the body will float to the surface, but how quickly this occurs depends on the temperature. A victim falling through thin ice in winter may not float to the surface until spring. Victims drowning in the heat of midsummer may reappear the next day.
If the Malaysian airliner that recently disappeared did go down in the Pacific, their bodies may never come to the surface. Cold, dense Antarctic water sinks and flows slowly northward along the bottom over several years. It does not freeze because of the salt content. The bodies may be totally consumed by marine life before the gases of putrefaction can accumulate sufficiently to float them.
Although rescue must occur before the brain cells have died, there are indications the body has a mechanism, the “mammalian diving reflex,” that can occasionally delay death well beyond the 10-minute limit. There are cases where a victim falling through an ice-covered pond was trapped without oxygen for over 30 minutes and were revived with no permanent harm. This occurs so rarely, the mechanism is unknown. It seems the victim must be young and the water cold, especially on the face. However rare, it is always a possibility, so rescue attempts must continue well past 10 minutes, even when it becomes obvious that it has become a body retrieval, not a rescue.