Fellow divers...I need some help

[WC46]

I am taking the SSI Dive Control Specialist Course. I have to give a 15 minute lecture on Hyperthermia and Hypothermia, dive related of course. I need some material. Can anyone help me?

[Suther2136]

DAN to the rescue



Alert Diver Article
Explore Diving's Diversity
May 2002 Issue
By: Dan Orr
Make Sure You're Prepared Before You Take the Plunge
Our land is wonderfully diverse. We can say the same about our diving venues: from north to south, east and west, the dive opportunities are boundless. Just about anything and everything you would hope to find in a dive site is available to the enterprising recreational diver. From wrecks to coral reefs, kelp forests to caves and caverns, the opportunities are there for you, the qualified diver, to enjoy. To enjoy these opportunities to the fullest, make sure you can meet the demands of the particular diving environment.
From a review of the DAN injury data and from conversations with diving professionals worldwide, I've noticed a recurring theme about dive problems: divers who dive in conditions in which they are ill-suited; and divers who use equipment with which they are unfamiliar.
We call this diving outside the personal safety envelope. As I have said in my Incident Insights columns, many factors, including the diver's training and experience, define the personal safety envelope. Divers can get into trouble when they venture beyond their experience and training.

Assess Your Experience
In discussing circumstances surrounding some dive fatalities, a diving professional and close friend, Tom Beasely, president of the Underwater Council of British Columbia, identified one problem he calls "warm to cold." This issue may contribute to injuries, fatalities and near-misses. It arises when a diver has training and experience limited to warm southern waters and then attempts to extend this to much colder dive sites.
Going from warm to cold waters, or cold to warm waters, can cause many problems. It involves increasing or decreasing your exposure protection, which may mean minimal exposure protection (e.g., swimsuit, diveskin or lightweight neoprene) or maximal exposure protection (e.g., neoprene wetsuit or drysuit).

Check Your Exposure Protection
Remember, however, that exposure protection is important even in relatively warm water. Progressive hypothermia can occur during long exposures in relatively warm, tropical waters. After all, water with temperatures of 80° F / 27° C is still nearly 20° F / -7° C below your body temperature.
With minimal exposure protection, divers generally require a minimum weight to maintain neutral buoyancy. Diving with a diveskin or swimsuit with the proper weight enables the diver to maintain neutral buoyancy throughout the water column. The only buoyancy change results from the loss of breathing gas from the cylinder. Divers wearing wetsuits or drysuits, on the other hand, can experience dramatic buoyancy changes as depth increases due to suit compression. Once they achieve neutral buoyancy, divers must be careful to control the significant increase in buoyancy during ascent.
A change in exposure protection often necessitates a dramatic change in your weighting system to compensate for the increased or decreased buoyancy of the exposure suit. An over-weighted or under-weighted diver is at increased risk in a number of ways. In both, the diver has to work harder to maintain control and thus increases risk.
Divers who have limited experience with wetsuits or drysuits may also experience increased stress: wearing a hood for the first time may pose problems for those with limited experience with exposure suits.
Before venturing into cold northern waters, divers should have practice with a wetsuit or drysuit, preferably under the guidance of a skilled instructor, under controlled conditions. For those who expect to dive in conditions that require a hood or gloves, wearing such accessories first in a pool or shallow water is good preparation.

Other Considerations
Cold. And it's not just you who can get cold: your equipment can, too. Regulator freeze-up can occur when a gas expands out of the cylinder into the regulator first stage. The expanding gas lowers the temperature of the first stage to the point where ice can form and cause the regulator to free-flow. The resulting rapid loss of breathing gas can have serious consequences. Divers who venture into northern waters might want to consider a regulator with an environmental package, which would reduce the likelihood of regulator freeze-up in cold waters.
Buoyancy. I have witnessed firsthand an interesting phenomenon that can occur when divers exchange air in deep water. When divers come together to buddy breathe, their body positions change from horizontal to vertical. This change causes suit compression in the lower extremities. The result is a slight increase in negative buoyancy.
When this occurs, if the divers pause before beginning a controlled emergency ascent, they will actually sink, making a safe ascent much more difficult. Sometimes the added difficulties of ascending, as well as the stress of the emergency ascent, are more than one or both divers can handle. The results can be tragic. Regulator free-flow can happen when two divers breathe simultaneously from a single regulator.
Dirty waters. Divers in warmer waters should always consider SAND. For those unaccustomed to diving in areas where sand is prevalent, they need to know how pervasive sand can be. Even the smallest particles can affect the proper function of inflator hoses and regulators, even causing them to leak.
The mastery of unfamiliar equipment (e.g., drysuit) is crucial. It is also important to consider whether you have the right equipment for your dive: drysuit, correct weights, light, compass.
Finally, before any dive excursion, and especially in unfamiliar conditions and with equipment new to them, divers should check with their buddy: they need to review essential skills and practice how to handle emergency situations, such as exchange of air.
Whether you go from warm to cold or vice versa, safe and enjoyable diving demands a mastery of skills and equipment. These skills allow you and your diving partner to reap the myriad benefits found in both southern and northern climes.

[kjvander]

Hyperthermia....you got too hot....either wearing too much exposure protection or water too warm....take off some clothes

Hypothermia...you got too cold....not wearing enough exposure protection....put clothes on.

much more scientific reply above.....but this is the layman's terms.