Drowning
Drowning is defined as respiratory impairment from being in or under a liquid. It is further classified by outcome into: death, ongoing health problems, and no ongoing health problems. Drowning itself is quick and silent, although it may be preceded by distress which is more visible.
Generally, in the early stages of drowning, very little water enters the lungs: a small amount of water entering the trachea causes a muscular spasm that seals the airway and prevents the passage of both air and water until unconsciousness occurs.
This means a person drowning is unable to shout or call for help, or seek attention, as they cannot obtain enough air. The instinctive drowning response is the final set of autonomic reactions in the 20–60 seconds before sinking underwater, and to the untrained eye can look similar to calm safe behaviour. Lifeguards and other persons trained in rescue learn to recognize drowning people by watching for these movements. If the process is not interrupted, loss of consciousness due to hypoxia is followed rapidly by cardiac arrest. At this stage, the process is still usually reversible by prompt and effective rescue and first aid. Survival rates depend strongly on the duration of immersion.
Terminology
Active drowning
People, such as non-swimmers and the exhausted or hypothermic at the surface, who are unable to hold their mouth above water and are suffocating due to lack of air. Instinctively, people in such cases perform well-known behaviours in the last 20–60 seconds before being submerged, representing the body's last efforts to obtain air. Notably, such people are unable to call for help, talk, reach for rescue equipment, or alert swimmers even feet away, and they may drown quickly and silently close to other swimmers or safety.
Dry drowning
Drowning in which no water enters the lungs
Near drowning
Drowning which is not fatal
Wet drowning
Drowning in which water enters the lungs
Passive drowning
People who suddenly sink or have sunk due to a change in their circumstances. Examples include people who drown in an accident, or due to sudden loss of consciousness or sudden medical condition.
Secondary drowning
Physiological response to foreign matter in the lungs due to drowning causing extrusion of liquid into the lungs (pulmonary edema) which adversely affects breathing
Silent drowning
Drowning without a noticeable external display of distress
