Under water, a person can hold his breath for about a minute. After that, an involuntary reflex for breathing movement takes over, taking water into the lungs. After two minutes, a cramp stage begins which is marked by a trembling diaphragm and spasms of the vocal cords. At this point, it is no longer possible to breathe. Death occurs in three to five minutes.
At first, an able swimmer (a non-swimmer with a life vest or an unconscious swimmer with an “unconscious safe” life vest) will remain on the surface of the water. However, even then it is possible to take water into the lungs from choppy water or sea spray (for example, in a storm or a strong wind in flowing waters).
When water enters the lungs, the breathable air is mixed with water, causing foam to form in the lungs. The air sacs in the lungs collapse, causing acute oxygen deficiency. The more pronounced this condition is, and the longer it lasts, the more damage occurs to the brain, heart, and lungs. Shock and death are potential results.
Every death in the water is generally considered to be “drowning”, however the actual cause of death is often not drowning but loss of consciousness, followed by drowning in the water. Death in the water does occur, but it is due to “atypical drowning”, also known as water shock.
Every kind of drowning that is triggered by some other factor (for example, a heart attack in the water, stroke, loss of consciousness, and so on) is referred to as secondary drowning. Primary drowning occurs almost always with non-swimmers or with divers who get stuck under the water until their air supply runs out.
The actual cause of death from drowning is oxygen deficiency (hypoxia), either from water entering the lungs or from so-called laryngospasm (spasms of the vocal cords).
Dry drowning occurs when the vagus nerve, located at the top of the larynx, is stimulated to the point that the heart slows down and stops beating. An impulse travels along a second nerve (the recurrent laryngeal nerve), which runs to the larynx muscle and triggers the laryngospasm. The irritation in the throat that leads to laryngospasm can usually be calmed, but in about 10% of the cases, it leads to dry drowning.
Numerous observations have confirmed that an overfull stomach can help trigger this reflex occurrence. This reflex action can also be triggered by an event such as a “hit below the belt” or by jumping into cold water, if the water hits the stomach hard enough. Even if there haven’t yet been any studies showing that diving leads to reflex death, it is conceivable that some unexplained diving accidents could have been caused by vasovagal reflex mechanisms.
Wet drowning occurs when water enters the airway unhindered, preventing the exchange of gasses.
In addition, the complete blood count is changed as described below. There is very little chance of being saved because, in addition to the complications caused by drowning, the lungs are also severely damaged (lung inflammation).
Drowning in Freshwater or Saltwater
There is a big difference between getting freshwater or saltwater into the lungs and, therefore, into the circulatory system. With freshwater, which contains virtually no salt, the water enters the bloodstream through the lungs, because the salt content of the blood is around 0.6%. The blood is diluted to a ratio of 1:1 within about four minutes.