Drowning

Definition

A reduced concentration of oxygen in the blood, hypoxemia, is common to all near-drownings. In the early stages of drowning, the person may initially gasp and aspirate small amounts of water. Hyperventilation and voluntary holding of breath may follow. The aspiration of small amounts of water triggers laryngospasm during which the trachea is sealed such that neither water nor air passes through. Hypoxemia results and asphyxia leads to relaxation of the airway, allowing water to enter and fill the lungs. This is referred to as “wet drowning”.

Drowning occurs very quickly. Within two to three minutes of submersion, most individuals are unconscious and within four to six minutes the brain begins to suffer from lack of oxygen.

Mammalian Diving Reflex

The mammalian diving reflex may allow some individuals to survive for longer periods in the water. The diving reflex may occur in young children who are suddenly submerged in cold water. This reflex slows the heartbeat, constricts peripheral arteries thereby directing more oxygenated blood to the heart and brain, and produces immediate apnoea that prevents aspiration. Respiratory and cardiac metabolism decreases, which in turn reduces the damage to organs. In some cases, children who have been submerged for extended time periods can be fully resuscitated.

Types of Drowning

Dry Drowning

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