Cold Water Near Drowning & Hypothermia
Mechanism, Diagnosis, and Treatment of Submersion-related Injuries
Oct 24, 2008
Cold water near-drowning is a submersion accident often leading to unconsciousness or coma in water temperatures of 70 degrees Fahrenheit (F) or less. A long submersion time is considered 4 to 6 minutes or greater. Prolonged submersion in cold water leads to hypothermia.
Hypothermia - Definition, Mechanisms, and Effects
Hypothermia occurs when body temperature is lowered to 95 degrees F or below. Hypothermia occurs by four main mechanisms:
- Conduction - heat transfer by direct contact with the water. Water conducts body heat away up to 26 times faster than air of the same temperature.
- Convection - heat transfer by water that moves away
- Radiation - heat loss from an unprotected head
- Evaporation - conversion of water droplets (sweat) into water vapor
Once body temperature drops below 95 degrees F, shivering sets in along with sensation of cold. Upon reaching 93 degrees F, loss of manual dexterity and muscle rigidity begin to develop. At around 86 degrees F, unconsciousness occurs and cardiac arrest generally occurs once temperature drops to 83 degrees F.
The Diving Reflex
This phenomenon occurs in mammals and birds and happens only in response to facial immersion in cold water. Cold receptors in the face are activated and trigger the heart rate to slow down and blood pressure to increase. The body essentially becomes a heart-brain perfusion circuit.
Low water temperature cools the brain and once brain temperature drops below 86 degrees F, the ability to survive prolonged oxygen deprivation improves. The diving reflex is one of the reasons that permanent brain damage risk is lower in cold water near-drowning than warm water near-drowning. The reflex is more prominent in young children and infants than in adults.
Factors Affecting Survival of , Signs and Symptoms of, and Treatment of Cold Water Near-drowning
Several factors impact whether an individual survives near-drowning and these include:
- age - the younger the better the prognosis
- length of submersion - the shorter the better
- water temperature - the colder the better the survival
- cardiopulmonary resuscitation (CPR) - the more appropriately done the better the survival
- water quality - the cleaner the better the survival
- struggle - the more the struggle the worse the results
- other injuries - burns, fractures reduce the survival
Signs and symptoms in a near-drowning victim include:
- Cough with clear to frothy red sputum
- Blue skin color
- Shortness of breath
- Alteration of consciousness, from confusion to coma
- Respiratory or cardiac arrest
Treatment after removal from the water involves the ABCs of resuscitation (airway, breathing, and circulation) with CPR administered if indicated. The Heimlich maneuver should be avoided as it may induce vomiting or aspiration. Oxygen should be provided and all wet or constricting clothing should be removed as quickly as possible. The victim should be transported to the nearest medical facility as quickly as possible to maximize the chance of survival.
References:
Immersion hypothermia and near-drowning. Scubadoc’s Diving Medicine Online Web site. http://www.scuba-doc.com/hypoth.htm. Accessed October 24, 2008.
Shepherd SM, Martin J, and Shoff WH. Drowning. EMedicine.com Web site. http://www.emedicine.com/emerg/topic744.htm. Updated February 11, 2008. Accessed October 24, 2008.
