Causes of drowning

Ruapehu Bulletin, Volume 8, Issue 371, 29 January 1991, Page 9

Causes of drowning

The causes of drowning are many and varied - foot entrapment, entrapment in hydraulic forces. entrapment through equipment (the scuba diver's weight belt which fails to release), loss of consciousness through head injury or hypothermia, through medical problems ( myocardial infraction [heart attack], cerebral infraction [stroke] and seizures [eg: epilepsy]), and spinal injury through diving from a height into shallow water. Prevention generally involves the obvious - become a better swimmer, do not swim in difficult water conditions (know one's limitations in water), do not mix alcohol and other recreational drugs with swimming and other aquatic recreation, and wear a standard approved buoyancy-aid, appropriate cold weather clothing and helmets when whitewater boating. You should note that there is no significant evidence that swimming right after an ordinary sized meal increases the incidence Of drowning. Any violent motion, however, may cause a victim to vomit stomach contents which may then cause a breathing obstructipn, or be inhaled in to the lungs. It is therefore, advisable not to participate in

white water boating or go out into the surf immediately after a heavy meal. It is very important to recognise the behavioural symptoms during drowning at the earliest moments. of a victim's plight. This is not as easy as it seems, for the symptoms can look like play. Nonswimmers' diffficulty Non-swimmers, or those in difficulties, display instinctive arm movements in the first critical 20-60 seconds of the drowning episode. The victim is attemptmg to keep their head above water so that they can breathe. They have instinctive downward arm movements with the arms partially extended from the sides, and flap up and down in unison. The head goes up and down in the water. The victim is unable to call for help as breathing, not speech, has become the primary survival function. They will be unable to wave for distress in the recommended manner with a raised arm. This very rapid movement leads to high energy use and rapid exhaustion. In cold water heat loss is very rapid and hypothermia will hasten the drowning event. The victim's breathing will become

rapid and shallow (not to be confused with hyperventilation) which leads to a build up of carbon dioxide in the blood, and rapid depletion of oxygen. Recognising these instinctive arm movements is the key to early rescue, and is of obvious importance to those in charge of people who are swimming. This initial struggle will be replaced by periods of volunteer breath holding. The victim may be seen floating face down on the surface, unconscious. The eventual build-up of carbon dioxide in the blood will stimulate the respiratory centre to breathe. Swallowing water will occur (whether laryngospasm has taken place or not) which will cause vomiting and possible aspiration of water and vomit. Terminal gasping with the flooding of the lungs will then follow. The victim will lose buoyancy as the lungs fill with water, and will sink to the bottom. Cardiac arrest will follow, if it has not already taken place.