Archive for the ‘Blogroll’ Category

Cold-Related Injuries #7 – Hypothermia

December 10, 2006

HYPOTHERMIA

Hypothermia is a lowering of body’s core temperature to level where normal brain & muscle function are impaired.
It is the one of the most common threats and causes of wilderness emergencies.
We are a hairless mammal, designed for the hot tropics, not the cold environs.
We have little or no defense against the cold, other than behavior, i.e., wear warm clothing.

THERMOREGULATION:
Balance of heat production & heat loss.
Thermoequilibrium is monitored & controlled by the brain.
Thermoregulation is performed by the skin, via the vasculature.

Heat Production: 
Internal sources:
Basal metabolism – burning of glucose to produce heat
Nutrition/digestion – “logs on the fire”
Exercise/shivering – muscle contraction to produce heat (as byproduct)
External sources:
Fire, stoves, sun, other people

Heat Loss:         
Conduction – heat transfer from one solid object to another
Convection – heat transfer from solid object to air
Radiation – infrared energy given off by warm objects      
Evaporation – heat transfer to water during liquid to gas change

Body’s defensive reaction to cooling off: 

NO WARNING OF IMPENDING DOOM
Peripheral vasoconstriction
– skin’s attempt to decrease heat loss.
Involuntary shivering – muscles’ attempt to produce heat.
Increased basal metabolism – may increase to 5 times its normal rate.

For more detailed information on Hypothermia see the Jan/Feb 2004 issue, When Jack Frost Bites, and the Nov/Dec 2004 issue, Frozen Mythbusters, of the Wilderness Medicine Newsletter. Click on this link to learn more about or subscribe to the Wilderness Medicine Newsletter.

This blog is powered by the Wilderness Medicine Newsletter, now celebrating 20 years of publication. The WMN is published and distributed online six times each year by TMC Books, and subscriptions cost as little as $10 per year. To find out more, or to subscribe online, click here.

Cold-Related Injuries #6 – Raynaud’s Disease

December 8, 2006

Raynaud’s Disease:

This is also a non-freezing cold injury. 
It is a hypersensitivity reaction to cold exposure.
It is more of a nuisance than a limb-threatening injury.
This condition has been caused by chronic cold exposure and, for some unknown reason, the peripheral circulation has now developed an exaggerated response to the cold which now occurs at warmer temperatures, i.e., not as cold as it used to have to be.  The peripheral circulation in the hands and/or feet will now overreact and vasoconstrict or close down too much.
So, the response is too early and too much.
Upon rewarming, there is also an exaggerated response: the skin will turn red, and painful.  The extremity may also throb with pain during the rewarming process.
Once rewarmed the tissues should return to normal.

Treatment of Raynaud’s:

Avoid and limit cold exposure.
Keep the affected areas well-insulated, warm, and dry.
Avoid nicotine, caffeine, alcohol, and over-the-counter decongestants.
Drugs:  may try calcium channel blockers for their vasodilatory effects.
 Eg:  Nifedine XL 30 – 90mg po qd, or diltiazem 30 – 120mg po qid.
“Pavlovian” response trials, also known as Murray’s Method (for Dr. Murray Hamlet),  a technique to re-educate the nerves affecting the vasculature.

Rehabbing Raynaud’s or Murray’s Method:

Equipment: 2 – 4 Styrofoam coolers, 2 for hands + 2 for feet.
Warm water.
Warm inside & cool, <32°F (0°C) outside.
Fill the Styrofoam coolers with warm water, 105°F – 110°F, one set inside and one set outside.
Start inside, dressed lightly so that you are comfortable, and sit with your hands or feet in the warm water for about 5 mintues; then, get up and go outside.  Stay lightly dressed, and put your hands or feet in the warm water outside, for 5 – 10 minutes. 
For this to work your body has to be able to cool off while your hands and feet stay warm.  This is the re-education process.
You have to repeat this process about 50 times.  It seems to be most effective when you do this about 5 times a day, every other day.

Click on the images below to see full size.

raynauds-2-for-blog.gif   raynauds-1-for-blog.gif

For more detailed information on Raynaud’s Disease see the Jan/Feb 2005 issue of the Wilderness Medicine Newsletter, Non-Freezing Cold Injuries.  Click on this link to learn more about or subscribe to the Wilderness Medicine Newsletter.

This blog is powered by the Wilderness Medicine Newsletter, now celebrating 20 years of publication. The WMN is published and distributed online six times each year by TMC Books, and subscriptions cost as little as $10 per year. To find out more, or to subscribe online, click here.

Cold-Related Injuries #5 – Trenchfoot/Immersion Foot

December 6, 2006

TRENCHFOOT/IMMERSION FOOT

A non-freezing cold injury that is caused by continual dampness and cold of the hands or feet.
The wet and cold causes vasoconstriction of the peripheral circulation in the hands or feet reducing blood flow, causing ischemia. 
The skin can survive with reduced circulation for about 6 hours; after that it will die from ischemia. 
The resulting injury is severe, painful, and lifelong.

Cause: 
Vasoconstriction deprives hands or feet of adequate blood supply for too long.

Symptoms:
While wet and cold: 
The extremities are cold, wet, numb, and macerated (wrinkled from being waterlogged).  
With rewarming: 
The extremities become red, swollen, painful; may lead to gangrene or nerve damage.

Treatment:  TREAT THE WHOLE PATIENT
Remove all wet clothing.
Get them dry & Keep them dry.
Reinsulate  & Rewarm.
Hydrate & Feed with sickly sweet drinks – warm liquid Jello is best because it has lots of calories.
Do not allow them to get cold and wet again.
NSAID’s;  eg. ibuprofen 800mg po tid, may be given with Tylenol for pain relief.
Evacuate.

PREVENTION:
Keep hands and feet dry.
Change socks regularly.
Sleep in dry socks at night.
Make sure foot gear is not too tight, impairing circulation.
Do not tolerate cold, numb, wet extremities – Do something!

For more detailed information of trench/immersion foot injuries see the Jan/Feb 2005 issue of the Wilderness Medicine Newsletter, Non-Freezing Cold Injuries.  Click on this link to learn more about or subscribe to the Wilderness Medicine Newsletter.

This blog is powered by the Wilderness Medicine Newsletter, now celebrating 20 years of publication. The WMN is published and distributed online six times each year by TMC Books, and subscriptions cost as little as $10 per year. To find out more, or to subscribe online, click here.