Warm Water Hypothermia

Can Hypothermia occur in warmer ocean water? Is warm-water Hypothermia even possible? Well to answer this question, we must first begin with trying to understand what exactly Hypothermia is.

Hypothermia is the condition in which the body’s core temperature drops below that required for normal metabolism and body functions. When the body is exposed to cold, and it cannot replenish the heat being lost from the core body temperature through internal mechanisms, hypothermia is said to set in.

Are you cold?

Have you ever noticed yourself start shivering, or feeling cold while Scuba Diving even in warm tropical waters? The water that we dive in is almost always at a lesser temperature than that of our bodies; and water conducts/draws away heat from a divers body almost 25 times more efficiently than air, which is why , even after a short dive in seemly mild water temperatures, it is possible to get mild hypothermia.

The NOAA Diving Manual discusses this subject in and states:

“Divers also have to be wary of hypothermia in warm environments. A phenomenon called “warm water hypothermia” can occur even in the tropics, especially during long dives and repetitive dives made without adequate re-warming between dives. In warm water hypothermia, long slow cooling can take place in water temperatures as warm as 82 degrees F – 91 degrees F. Although warm water hypothermia is not easily recognized as its cold water counterpart, it definitely warrants attention.

In a nutshell, you can get hypothermia when your core body temperature drops below normal rate and your body’s heat generation abilities cannot keep up to the heat loss. Any time a body is in an environment that is colder than 98.6 F (37 C), heat is lost.  And since the heat loss in water is 25 times faster than to air, this may occur fairly quickly. Mild Hypothermia takes place while the core temp is still above 90F (32 C). Severe Hypothermia sets in when the core temp drops below 90F.

warming up

While warm water hypothermia isn’t clearly understood, it has been clearly demonstrated in various medical studies. This form of Hypothermia onset is also known as silent hypothermia since the symptoms of hypothermia do not set in immediately. It is said that since being in warm water, (warm being below the body temperature) the drop in the core temperature may not be rapid enough to activate the body’s thermo-regulator mechanism (shivering), the diver may still feel warm while his body is in fact cooling, which causes a sudden onset of severe hypothermia symptoms once the temperature falls beyond a certain level.

Beyond certain point It is said that there is no symptomatic difference between warm water and cold water hypothermia. The only difference is the time before the onset of symptoms, a diver facing warm water hypothermia may feel fatigue, loss of motivation and impaired mental ability, before feeling the actual symptoms of Hypothermia, where violent shivering sets in and loss of coordination.

Divers must always remain vigilant to these signs of shivering, wear adequate exposure protection gear and exit the water immediately to re-warm if you or your buddy begins to feel cold on the dive. Ensure that you spend a sufficient amount of time between dives getting warmed up even beyond your specified surface interval times especially if you felt cold on your first dive, as often rapid consecutive dives can lead to hypothermia.

photos from flickr by: Nataraj Metz , Saspotato

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