Physiological and Medical Considerations in the Winter Alpine Environment

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Physiological and Medical Considerations in the
Winter Alpine Environment
Altitude Illnesses
Hypothermia
Nutrition
Heat Loss
Heat Production
Hydration
Fitness
Taken from various internet and published sources.
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Heat Lossroom temperature

• Radiation 60
• Evaporation 25
• Convection 12
• Conduction 3

What happens in the mountains?
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Heat Gain

• Metabolic heat production
• Exercise
• Sympathetic stimulation
• Thyroid hormone
• Shivering
• Radiation, Conduction, Convection
• Food

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COLD STRESS

• Types of cold Injury
• Non-freezing
• Trench Foot
• Hypothermia exhaustion hypothermia
• immersion hypothermia

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COLD STRESS

• Freezing
• Frostbite
• -Extremities are at risk nose, ears,
  fingers, toes, penis, etc.
• -Never warm tissue if the potential for
  re-freezing exists.

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COLD INJURY PREVENTION
Eat
Eat frequently to maintain energy. Drink plenty
of water. Avoid tobacco. Avoid alcohol
Drink
Reduces self-protection Reduces
shivering Diuretic
But don't be merry
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COLD INJURY PREVENTION

• Clothing
• Clean and dry (avoid cotton)
• Layered, loose, and light
• Wear head protection
• Avoid restriction of blood to
  extremities

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Typical Conditions
Temperature?
Wind Speed?
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Hypothermia

• 98.6 Normal function
• 95 Distorted/slowed biomechanical reactions
• 90 Decreased cerebral blood flow
• Myocardial irritability, atrial fibrillation
• 82 Ventricular fibrillation
• 77 Changes in CV autoregulation, decreased HR
• 65 Asystole
• 61 Lowest reported adult hypothermia survival
• 59 Lowest reported infant hypothermia survival

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Central Nervous System EffectsHypothermia

• Most apparent system affected
• Slowing of speech, thinking, sensation
• Apathetic, listlessness
• Similar to stroke, head injury, or intoxication

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Cardio-Respiratory Effects Hypothermia

• Peripheral vasoconstriction
• Increased blood viscosity
• Decreased respiratory rate and volume
• SA node dysfunction leads to lower cardiac output
• Arrhythmias, V-fib
• Death can result from cardiac arrest
• (most common cause)

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Muscular System Effects Hypothermia

• Decreased function
• Decreased nerve conduction velocity
• Weak/slow contractions
• Shivering can result in hypoglycemia

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Brain
HYPOTHERMIA
Muscles
Heart
continuum
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Types of Hypothermia

• Mild
• Rectal Temp 90 - 94F
• Pale, cool
• Varying degrees of confusion, disorientation,
  incoherence, and ataxic gait
• May shiver uncontrollably
• Fine movements of the hand effected
• Tachycardia, tachypnea, cold diuresis

continuum
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Types of Hypothermia

• Moderate
• Rectal Temp 82 - 90F
• Impaired judgment
• Dilated pupils
• Muscle rigidity (shivering reflex is lost)
• Decreased BP, HR, respirations
• Cardiac arrhythmia
• MUST BE WARMED

continuum
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Types of Hypothermia

• Severe
• Rectal Temp lt 82F
• Patient appears dead
• Comatose
• Muscles are unreflexive
• Slow respirations, pulse
• BP undiscernible
• Arrhythmia leading to V-fib

continuum
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Brain
HYPOTHERMIA
Muscles
Heart
continuum
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Mild to Moderate Treatment

• Passive Rewarming
• Prevent further heat loss!!!
• Remove from cold/wind environment
• Remove wet clothing
• Insulate the body
• Keep patient supine

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Mild to Moderate Treatment

• Active rewarming
• Best to provide heat internally
• Warm humidified air or oxygen (112F max)
• Warm IV (104F max) ?
• Give warm fluids with sugar orally
• External sources
• Heating blankets, heat lamps, hot packs
• Apply to trunk only
• Use caution, Rewarming Shock
• Check for frostbite

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Severe Hypothermia Treatment

• Passive rewarming
• Be gentle, the heart is fragile
• Maintain airway
• CPR can cause a lethal arrhythmia
• Assess pulse for 45-60 seconds
• Defibrillation is usually ineffective lt 86F
• Not dead until warm and dead

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Severe HypothermiaDo Nots

• Do not try to actively rewarm (rewarming shock)
• Do not use direct heat
• Do not let them consume alcohol

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Rewarming Shock

• When the shell warms before the core
• Vasodilation can increase stress on heart
• Blood pressure can decrease
• Ventricular Fibrillation due to rapid return of
  cold blood to the heart

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Frostbite

• Ice crystals form in extracellular space
• Most commonly effects
• Feet and toes
• Hand and fingers
• Face and ears
• Scrotum and penis can be affected
• 3 degrees of frostbite
• frostnip
• superficial frostbite
• deep frostbite

continuum
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Predisposed to Frostbite

• Constrictive clothing
• Fatigue
• Alcohol
• Smoking
• Medications
• Atherosclerosis
• Diabetes
• Peripheral neuropathy
• Raynauds Phenomenon

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Frostnip

• 1st stage of frostbite
• Slow onset
• Sometimes unrecognized
• Skin color initially red, then turns white
• Pain or numbness in area of discoloration
• Skin surface and underlying tissue are still soft
• No freezing of tissue

continuum
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Treatment for Frostnip

• Warm the affected area
• Warm air
• Warm water
• Warmth from other body areas
• May experience tingling or burning sensation
  during rewarming

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Superficial Frostbite (2nd degree)

• Skin and subcutaneous tissue is involved
• White waxy appearance to mottled blue color
• Skin surface is hard, but underlying tissue is
  still soft
• Edema
• Numbness or dull pain lasting for days

continuum
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Superficial Frostbite Treatment

• Transport as soon as possible
• Rewarm the area
• warm water (100 - 105F)
• Insulate the area and maintain warm environment
• Cover blisters with dressing
• Do not put pressure on the area
• Pain during rewarming is a good sign

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Deep Frostbite (3rd degree)

• Deeper structures are affected
• Skin becomes white, then grayish yellow, and
  finally grayish blue
• All sensation lost
• Skin and underlying tissues become hard

continuum
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Deep Frostbite Treatment

• If frozen
• Leave frozen and pad area to protect from heat
• Notify hospital
• If partially thawed or hours away from hospital
• Rewarm before transport (100 - 105F)
• Insulate the area and maintain warm environment
• Cover blisters with dry sterile dressing

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Deep Frostbite Treatment

• Transport as soon as possible
• Limit movement even when thawed
• Do not put pressure on affected area
• If conscious - ok to give warm fluids
• Late management might require debridement of
  necrotic tissue or amputation

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FrostbiteDo Nots

• Do not rub the area
• ice crystals can cause damage
• Do not thaw a frozen limb if there is a chance it
  will be refrozen
• Refreezing causes more damage than extended
  freezing
• Do not use direct heat such as a hair dryer or
  heating pad
• Do not disturb blisters
• Do not allow the person to smoke or use alcohol

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Human Body and Fluids
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Fluid Requirements

• Rest 1 ½ liters a day
• Normal activities 2 ½ liters a day
• Mountaineering 6 liters a day

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Dehydration

• Symptoms
• headache
• dark urine
• dizziness, nausea
• weakness
• dry mouth, tongue, throat, lips
• lack of appetite
• stomach cramps or vomiting

• irritability
• decreased amount of urine being produced
• mental sluggishness
• increased or rapid heartbeat
• lethargic
• unconsciousness

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• What is the universal symptom of dehydration?
  

Headache
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Dehydration

• Prevention
• Start the day with 1-2 liters
• Drink minimum of 3-6 liters of fluid per day
• Do not wait until you are thirsty
• Monitor urine color
• Avoid sweating, alcohol, caffeine

Drink
Water
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Dehydration

• Treatment
• drink water or other warm liquids
• do not eat snow
• rest

Drink
Water
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Some Nutrition Facts

• All forms of fuel are stored in the body and
  eventually broken down into glucose as needed
• Carbohydrates Rapid, fuels stored in cells
• Muscle protein broken down when carbohydrate
  stores are low
• i.e. Carbohydrates will help prevent muscle loss
• Fats mobilized for fuel when carbohydrates are
  low
• will last for days to weeks

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Nutritional Requirements

• Basal 1400-2000 calories a day
• Cold weather mountaineering 5000 calories a day

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Nutrition

• Long-term
• Grazing diet
• 40/30/30
• Short-term
• Carbs
• Poorly tolerated
• Fats

Debatable
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Altitude Fitness
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Factors Affecting Acclimatization

• Age
• Fitness
• Medical conditions

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General Fitness

• It helps to be fit
• After acclimatization,
• the fit at low altitude will be fit at
  high altitude
• but will be less fit than at low altitude

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Normal Acclimatization

• Heart rate ?
• Respiratory rate ?
• Breathless on exercise
• Hungry
• Urine output ?
• Sleepy
• Headache

• All symptoms should disappear or get better after
  rest, food and water

Humm..what if the person doesnt get better?
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Cardiovascular Fitness Training

• Aerobic training
• Exercise at 60-70 of maximum heart rate
• Max HR220-age
• Anaerobic training
• Exercise at 100 of max HR for a couple minutes a
  few times a week

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General Training

• Strength
• Free weight or machine work out
• All major muscle groups twice a week
• Flexibility
• End with stretching, e.g., Yoga
• Balance

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Altitude Illness
Oxygen
AMS vs. HAPE vs. HACE
continuum
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Mt. Baldy
Everest
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AMS
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Mechanisms of AMS

• AMS is not directly caused by hypoxia
• Oxygen levels throughout the body drop within
  minutes of exposure but AMS takes several hours
  to develop.

Mechanisms..........
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Mechanisms of AMS

• High intracranial pressure due to increased
  leakage of fluid may possibly cause AMS

brain leaks
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Mechanisms of AMS

• General fluid retention possibly via the
  renin-angiotensin-aldosterone system or
  antidiuretic hormone

kidneys slow output
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What are the Predictors of AMS?
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NOTHING
!
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Risk Factors for AMS

• Rapid ascent
• Heavy exertion at altitude
• Residence at sea level
• Altitude, uncommon lt7,500 ft
• Hx of prior AMS
• Young age (less common at age gt50yrs)
• Physical fitness not protective

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AMS Differential Diagnosis

• Dehydration
• Hypothermia
• Exhaustion
• Hangover
• Viral illness
• Sedative or hypnotic medication
• Carbon monoxide poisoning

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Prevention of AMS

• Spend a day or so at base camp before starting
  ascent
• Once above 8,200 ft, do not climb higher than
  2,000 ft in 24 hrs
• Climb high but sleep low
• If climbing to over 9,800 ft in 1 day or with Hx
  of prior AMS or HACE, take prophylactic
  medications

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Symptoms of Mild AMS

• Headache
• Malaise
• Anorexia
• Low urine output

• Nausea/vomiting
• Dizziness
• Dyspnea on exertion
• Dry cough
• Inner chill

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Any symptom of AMS should be considered due to
altitude unless proven otherwise.Headache is
the most common.
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Natural History of Mild AMS

• Usually self-limiting
• If untreated may persist for weeks
• May progress to moderate and severe forms of AMS
  or to death
• Responds well to treatment

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Moderate AMS

• Ataxia
• Single most useful sign for deterioration
• Lassitude
• Strange behavior
• Confusion
• Impaired judgement
• Consciousness level ? ? coma
• Shortness of breath

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Treatment of Moderate AMS

• Stay at altitude, do NOT go further
• Descend if symptoms do not improve or get worse
• Water
• Rest
• Deep breathing every 4-6 minutes
• Diamox, Dexamethasone
• Give oxygen if available
• Use hyperbaric bag

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If in doubt...
Go down
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Prevention of AMS

• Acetazolamide 125-250 mg twice a day ?
• Ginkgo biloba 60 mg 1-3 times a day ?
• Dexamethasone 4 mg four times a day
• No support for nifedipine, furosemide, or codeine

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HACE
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High Altitude Cerebral Edema

• Symptoms include those of AMS, plus
• Any kind of neurological disorder ataxia,
  irrationality, hallucinations
• Can be accompanied by hemorrhages or thrombosis
• HACE is life threatening. Untreated, the person
  will fall to a coma and die within hours to one
  or two days.

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High Altitude Cerebral EdemaTreatment

• Descend!!
• Hyperbaric chamber
• Dexamethasone

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HAPE
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High Altitude Pulmonary Edema (HAPE)

• Accounts for most deaths from high altitude
  illness but uncommon (0.1-0.4 of travelers
  gt7,500 ft)
• Risk factors are same as from AMS
• Cold is also a risk factor (increased PAP from
  sympathetic response)
• More common in those with pulmonary vascular
  disease

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Clinical Presentation of HAPE

• Usually seen on 2nd night at altitude
• Dry cough, then frothy sputum, then blood-tinged
  sputum
• Crackly, rattlely breathing
• Rapid breathing
• Increased heart rate
• Cyanotic lips, face, fingernails
• Mild fever is common

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Prevention of HAPE

• Slow ascent (Climb high, sleep low)
• Above 8,200 ft limit ascent to 2,000 ft daily.
  Add rest day every 2,000 4,000 ft
• Acetazolamide, Ginko biloba, cocoa, anti-asthma
• Special precautions in climbers with Hx of HAPE
• Nifedipine
• Salmeterol

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Treatment of HAPE

• Immediate descent mandatory
• Supplemental oxygen
• Hyperbaric therapy if available
• Medication Nifedipine, Diamox
• Mortality without medication- 50

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Acetazolamide Diamox

• Carbonic anhydrase inhibitor
• Diuretic
• Side effects
• water loss, tingling, sulphur allergies
• Dosage
• 125-250 mg twice daily ?
• start the day before the ascent
• acetazolamide does not mask the symptoms of
  altitude sickness

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Gingko Biloba

• Might be useful
• Recent studies suggest benefit at altitude
• Possible alternative to acetazolamide for people
  with sulphur allergy
• Dosage 60 mg 1-3 times/day ?

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Coca

• South American locals chew coca leaves
• Exact mechanism not known
• Seems to be useful

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Anti-Asthmatic Medication

• Seems to improve ventilation
• Long term studies still pending
• (what about asthmatics at altitude?)

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Novel Approaches

• Levitra
• Cialis
• Viagra

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PORTABLE HYPERBARIC CHAMBER
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THE GOLDEN RULES
If you feel unwell at altitude, it is high
altitude illness until proven otherwise. Never
ascend with symptoms of AMS. If you are getting
worse or have HACE or HAPE, get down immediately.
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HAFE high altitude flatus expulsion

• Expanding bowel gases at altitude
• Irritating to your partners

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