Archive for November, 2006

Cold-Related Injuries #3

November 30, 2006

FUEL AND WATER REQUIREMENTS TO STAY WARM

How much food/fuel and water do we need on a daily basis, not only live, but to be able to maximize our performance?  Dehydration may not rapidly lead to death but, it will definitely decrease and impair normal physical and mental abilities.  So, to be at our best we have to stay well hydrated and well fed – fuel to burn.

NUTRITIONAL REQUIREMENTS = average of 2500 CALORIES/DAY

Carbohydrate = 4cal/gram 60%
    (200 – 400 grams/day = 1200 -1600 cal/day)
Fat   = 9cal/gram  10%
    (20 – 60 grams/days = 180 – 540 cal/day)
Protein = 4cal/gram  30%
    (30 – 55 grams/day  = 120 – 220 cal/day)

Number of calories required varies with activity:
Normal daily activity:  2000 – 2500 calories/day.
Winter outdoor sports:  3000 – 4000 calories/day
High altitude mountaineering:  4000 – 6000 calories/day.

HYDRATION REQUIREMENTS = average of 2 LITERS/DAY

Normal water losses per day:  
Insensible loss:   nl temp.    hot temp.     heavy exercise
Skin  =      350ml          350ml           350ml
Respiration  =      350ml          250ml           650ml
Sweating  =     100ml         1400ml         5000ml
Urination  =    1400ml         1200ml          500ml
Defecation  =      100ml         100ml           100ml
TOTALS        2300ml      3300ml        6600ml

Water requirements will vary with activity, sweat output, and altitude.
Exertional sweat loss is 1 – 3 liters/hour for up to 4 hours without replacement.
        (can lose up to 3 liters per hour for 4 hours = 12 liters or 3 gallons = 24 pounds)
Altitude has a very low vapor pressure = will lose 1 cup/hour via respirations.
            (or 24 cups/24 hours = 6 quarts or liters)                                                     
        
LIFE AT ALTITUDE:
O – 8000 feet  = normal elevations for humans to live within.
8000 – 14000 feet = upper limits of sustainable life.
14000 – 18000 feet (½ atmosphere) = high altitude, can visit.
18000 – 28000 feet very high altitude, constant negative deficit, the death zone.

More detailed information in the Jan/Feb 2004 issue of the Wilderness Medicine Newsletter.

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Cold-Related Injuries #2

November 29, 2006

THE HUMAN ANIMAL

How do we stay warm? How do we produce heat? How do we regulate our core temperature?

Heat Regulatory Mechanism:
We “evolved” in the tropics and subtropics.
Therefore, we have a very sensitive and efficient heat regulatory mechanism.
We are naked, hairless, with sweat glands.
All warm-blooded animals use the evaporation of water to cool. 
Humans sweat; the evaporation of water off the skin cools the skin and blood.
Fur-covered mammals & birds pant, evaporating water out of the lungs thus cooling the pulmonary circulation.

Heat Production and Heat Loss

Heat Production: 
Basal metabolism, we burn glucose as a fuel to produce heat.
Metabolic activity set by thyroid, can be increased 5x’s.
Exercise – muscle activity.
Voluntary or involuntary = shivering, increases up to 10x’s.

Heat Conservation: 
Vasoconstriction in the skin.
Piloerection – hair stands on end.
Abolition of sweating.
           
Heat Loss: 
Conduction: 
Transfer of heat from one solid object to another. 
0% – 40%  depending upon the type of solid material
Convection:  Transfer of heat from a solid object into the air or water. 
0% – 40% depending upon air penetration
Radiation:   Transfer of heat by infrared radiation. 
5% – 80% depending upon surrounding temperature
Evaporation:  Transfer of heat by the evaporation of water. 
0% – 90% depending upon vapor pressure & moisture

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Cold-Related Injuries #1

November 27, 2006

FROSTBITE

We have just seen our first case of frostbite for this winter season.  An individual spent most of the night outside, barefoot, at about 20F.  They have a combination of superficial frostbite and immersion foot and may lose their toes– only time will tell.  Thus, we are inspired to produce several blogs that will deal with the recognition and management of Frostbite and the non-freezing cold injuires – Immersion Foot and Raynaud’s Disease. 

But first prevention:

WINTER WISDOM:  The Principles of Prevention of Hypothermia and Frostbite:
Know your personal limits and equipment.
Have proper-fitting clothing and boots.
Beware of tight-fitting boots or crampons.
Wear multiple layers, including socks.
Carry spare mittens and socks.
Control the rate of sweating.
Keep extremities WARM & DRY.
Keep the whole body warm, dry, well-fed, and well-hydrated.
Drink more than you think you need; do not rely on thirst to tell you to drink.
Carry and eat lots of carbohydrates; you burn glucose to stay warm.
React quickly to the very first signs of cold, numbness, or tissue changes.

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High Altitude Resources

November 23, 2006

There have been requests for some resources on more information about high altitude physiology and medicine.  Here are several resources that we have found to be very informative.

References:  

www. ISMMED.org  (International Society of Mountain Medicine) 

www.High-Altitude-Medicine.com

www.altitudephysiology.org

Paul Auerbach, MD, his text: Wilderness Medicine (The 5th Edition will be out soon.)

Charlie Houston, MD, his text:  Going Higher

Two excellent articles are:

www.emedicine.com/emerg/topic795.htm – Emedicine article on HAPE

www.emedicine.com/EMERG/topic22.htm – Emedicine article on HACE

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Emergency First Aid Kit for High Altitude Expeditions

November 23, 2006

Post #6 of 6:

Emergency First Aid Kit for High Altitude Expeditions

The most recent issue of the Wilderness Medicine Newsletter, Nov/Dec 2006, is dedicated to the recognition and management of high altitude illnesses.  To follow is a series of postings regarding high altitude illnesses, recognition and management.

Drugs specific to high altitude illnesses:

For a group of 8 – 10, carry 2 full doses of each medication.
Diamox (Acetazolamide) 250mg tablets, #30
Procardia, Adalat (nifedipine) 10mg tablets, #40 or SR 30mg tablets #30
Decadron (dexamethasone) 8mg tablets, #20
8mg tablets can be split in ½ to make 4mg, or can carry 4mg tablets as well)
IM dosing: 24mg/ml, available in 5ml vials. 

Oxygen, nasal cannula, PEEP
Pulse Oximeter & spare battery
Emergency Rescue High Altitude Pressure Chambers:

Gamow bag, Cretec bag, PAC bag:
For information go to High-Altitidue-Medicine.com and check on hyperbaric treatment for links on how to purchase or rent.

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HIGH-ALTITUDE PULMONARY EDEMA (HAPE)

November 21, 2006

Post #4 of 6:

The most recent issue of the Wilderness Medicine Newsletter, Nov/Dec 2006, is dedicated to the recognition and management of high altitude illnesses.  To follow is a series of postings regarding high altitude illnesses, recognition and management.

HIGH-ALTITUDE PULMONARY EDEMA (HAPE)
HAPE = Fluid in the lungs.

Signs & Symptoms: Acute Mountain Sickness plus

Extreme fatigue
Shortness of breath at rest
Fast shallow breathing
Pulmonary crackles
Persistent cough with or without sputum
Dyspnea not relieved with rest
Chest tightness, pressure, congestion
No pain (if pain present, suspect injury, acute MI, or costochondritis)
Cyanosis of the lips and fingernail beds
Drowsiness

Treatment:

IMMEDIATE DESCENT – at least 500 – 1000 meters
If unable to descend, then place in pressure bag, Gamow, Certec, or PAC
Administer O2 if available, will relieve symptoms within minutes
Hydrate
Monitor SaO2 by pulse oximeter

Drugs:

Nifedipine (Adalat, Procardia), this is a calcium channel blocker that aids in HAPE by causing pulmonary vasodilation.
Nifedipine 10mg po every 6 hours, may use Nifedipine SR (slow release form) 30mg po every 8-12 hours, total dose not to exceed 90 – 120mg/day.
Acetazolamide (Diamox), is a carbonic anhydrase inhibitor helps to accelerate acclimatization.  It may used help prevent AMS and HAPE but, it is not effective for the treatment of HAPE.

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.

HIGH-ALTITUDE CEREBRAL EDEMA (HACE)

November 19, 2006

Post #5 of 6:

The most recent issue of the Wilderness Medicine Newsletter, Nov/Dec 2006, is dedicated to the recognition and management of high altitude illnesses.  To follow is a series of postings regarding high altitude illnesses, recognition and management.

HIGH-ALTITUDE CEREBRAL EDEMA (HACE)
The majority of cases of HACE occur because they continued to ascend while they still had the symptoms of Acute Mountain Sickness.
Signs & Symptoms: Severe AMS plus

Change in mentation or the ability to think and solve simple problems
Loss of coordination – ataxia, can be subtle but cannot tandem-gait walk
Possible hallucinations
Drowsiness
Coma
Cheyne-stokes respirations
Signs of increasing Intracranial Pressure (ICP)

Treatment:

IMMEDIATE RAPID DESCENT at least 500 – 1000 meters
If unable to descend, place in pressure bag, Gamow, Cretec, or PAC bag
Administer O2 if available, 4-6 lpm by nasal cannula or with PEEP
Hydrate if conscious
Monitor SaO2 by pulse oximeter

Drugs:

Dexamethasone (Decadron), 8mg po or IM stat, then 4mg po or IM q6h
Oxygen, 4-6lpm by nasal cannula or with PEEP, titrate as needed

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ACUTE MOUNTAIN SICKNESS (AMS)

November 17, 2006

Post #3 of 6:

The most recent issue of the Wilderness Medicine Newsletter, Nov/Dec 2006, is dedicated to the recognition and management of high altitude illnesses.  To follow is a series of postings regarding high altitude illnesses, recognition and management.

ACUTE MOUNTAIN SICKNESS (AMS)

Greatest danger is that untreated AMS may progress to life-threatening HAPE or HACE.
Don’t go up until the symptoms go down!

Signs & Symptoms: diagnosis is made when they have a headache and one or more of the following symptoms:

nausea with or without vomiting
fatigue or weakness
loss of appetite
dizziness or light-headedness
insomnia – difficulty sleeping

Treatment: Don’t go up until the symptoms go down!

Do not go any higher until all symptoms have cleared, which indicates acclimatization to that altitude.

Descend to the last sleeping altitude where they were symptom free or descend as far as necessary for improvement; 500 to 1000 meters is usually sufficient.

Continuing on with symptoms of AMS increases the risk of HAPE, HACE, and DEATH.

Rest, Rest, Rest, and Drink, Drink, Drink.

Hydration status is based on the color of urine they are producing.

If they decide to stay at altitude to acclimatize, if symptoms do not improve within 12 to 24 hours, DESCEND.

Drugs:


Mild analgesics: acetaminophen, paracetamol, aspirin, or ibuprofen.

Acetazolamide (Diamox), 250mg po (by mouth) every 12 hours until symptoms improve.
Children may take 2.5mg/kg body weight po every 12 hours.

For severe AMS:
Dexamethasone (Decadron), 4mg po every 6 hours.
Children may be given 1mg/kg body weight po up to 4mg and a second dose in 6 hours.

Oxygen, 2 – 4 liters per minute by nasal cannula, titrate up as needed.

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THE GOLDEN RULES OF ASCENT

November 15, 2006

Post #2 of 6:

THE GOLDEN RULES OF ASCENT:

  1. If you are ill at altitude, it is altitude illness until proven otherwise.
    Ill at altitude = altitude illness!
  2. Never ascend with symptoms of AMS.
    Don’t go up until the symptoms go down!
  3. If you are getting worse (or have HAPE or HAPE), go down at once.
    Continue down until you have relief of symptoms!
  4. Gain no more than 1000 ft of sleeping altitude per day
    Climb high and sleep low!

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High Altitude Illness

November 13, 2006

Post #1 of 6:

The most recent issue of the Wilderness Medicine Newsletter, Nov/Dec 2006, is dedicated to the recognition and management of high altitude illnesses. To follow is a series of postings regarding high altitude illnesses, recognition, and management.

What is High Altitude?
The scientific consensus for the definitions of altitude are:

High altitude: 1500 – 3500m (5000 – 11500ft)
Very High Altitude: 3500 – 5500m (11500 – 18000ft)
Extreme High Altitude: above 5500m (18000ft)
18,000′ (5500m) is ½ atmosphere

What are the RISKS of HIGH ALTITUDE MOUNTAINEERING?

As you go Higher it gets COLDER & DRYER, less and less OXYGEN, and more and more UV LIGHT that combing to CAUSE:

Dehydration (exhale 250cc of water per hour or 6 liters per day)
Hypothermia (may need up to 6000 calories per day)
Frostbite (dehydration contributes to the risk of frostbite)
Snow blindness (UV light concentration increases 4% every 1000′)
Severe sunburn (UV light concentration increases 4% every 1000′)
Acute Mountain Sickness (signs of lack of acclimatization)
High Altitude Pulmonary Edema (wet lungs)
High Altitude Cerebral Edema (wet brain)

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.