Transcript Drink plenty of water

Physiological and Medical
Considerations in the
Winter Alpine Environment
Taken from various internet and published sources.
Heat Loss
room temperature
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Radiation: 60%
Evaporation: 25%
Convection: 12%
Conduction: 3%
Heat Gain
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Metabolic heat production
Exercise
Sympathetic stimulation
Thyroid hormone
Shivering
Radiation, Conduction, Convection
Food
COLD STRESS
Types of cold Injury:
Non-freezing
Trench Foot
Hypothermia: exhaustion hypothermia
immersion hypothermia
COLD STRESS
Freezing
Frostbite
-Extremities are at risk: nose, ears,
fingers, toes,
penis, etc.
-Never warm tissue if the potential for
re-freezing exists.
COLD INJURY PREVENTION
Eat frequently to maintain energy.
Drink plenty of water.
Avoid tobacco.
Avoid alcohol:
Reduces self-protection
Reduces shivering
Diuretic
COLD INJURY PREVENTION
Clothing
Clean and dry (avoid cotton)
Layered, loose, and light
Wear head protection
Avoid restriction of blood to
extremities
Typical Conditions
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
Central Nervous System Effects
Hypothermia
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Most apparent system affected
Slowing of speech, thinking, sensation
Apathetic, listlessness
Similar to stroke, head injury, or intoxication
Cardio-Respiratory Effects
Hypothermia
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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)
Muscular System Effects
Hypothermia
– Decreased function
– Decreased nerve conduction velocity
• Weak/slow contractions
– Shivering can result in hypoglycemia
HYPOTHERMIA
Types of Hypothermia
• Mild
– Rectal Temp 90° - 94°F
– Pale, cool
– Varying degrees of confusion,
disorientation, incoherence, and ataxic gait
– May shiver uncontrollably
– Fine movements of the hand effected
– Tachycardia, tachypnea, cold diuresis
Types of Hypothermia
• Moderate
– Rectal Temp 82° - 90°F
– Impaired judgment
– Dilated pupils
– Muscle rigidity (shivering reflex is lost)
– Decreased BP, HR, respirations
– Cardiac arrhythmia
– MUST BE WARMED
Types of Hypothermia
• Severe
– Rectal Temp < 82°F
– Patient appears dead
– Comatose
– Muscles are unreflexive
– Slow respirations, pulse
– BP undiscernible
– Arrhythmia leading to V-fib
HYPOTHERMIA
Mild to Moderate Treatment
• Passive Rewarming
– Prevent further heat loss!!!
• Remove from cold/wind environment
• Remove wet clothing
• Insulate the body
• Keep patient supine
Mild to Moderate Treatment
• Active rewarming
– Best to provide heat internally
• Warm humidified air or oxygen (112°F max)
• Warm IV (104°F 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
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 < 86°F
• Not dead until warm and dead
Severe Hypothermia
Do Nots
• Do not try to actively rewarm (rewarming
shock)
• Do not use direct heat
• Do not let them consume alcohol
Rewarming Shock
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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
Frostbite
• Ice crystals form in extracellular space
• Most commonly effects
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Feet and toes
Hand and fingers
Face and ears
Scrotum and penis can be affected
• 3 degrees of frostbite
– frostnip
– superficial frostbite
– deep frostbite
Predisposed to Frostbite
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Constrictive clothing
Fatigue
Alcohol
Smoking
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Medications
Atherosclerosis
Diabetes
Peripheral neuropathy
Raynaud’s Phenomenon
Frostnip
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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
Treatment for Frostnip
• Warm the affected area
– Warm air
– Warm water
– Warmth from other body areas
• May experience tingling or burning sensation
during rewarming
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
Superficial Frostbite Treatment
• Transport as soon as possible
• Rewarm the area
– warm water (100 - 105°F)
• 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
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
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 - 105°F)
– Insulate the area and maintain warm environment
– Cover blisters with dry sterile dressing
Deep Frostbite Treatment
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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
Frostbite
Do 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
Human Body and Fluids
Fluid Requirements
• Rest: 1 ½ liters a day
• Normal activities: 2 ½ liters a day
• Mountaineering: 6 liters a day
Dehydration
• Symptoms
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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
• What is the universal symptom of
dehydration?
Headache
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
Dehydration
• Treatment
– drink water or other warm liquids
– do not eat snow
– rest
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
Nutritional Requirements
• Basal: 1400-2000 calories a day
• Cold weather mountaineering: 5000
calories a day
Nutrition
• Long-term
– “Grazing” diet
– 40/30/30
• Short-term
– Carbs
• Poorly tolerated
– Fats
Altitude & Fitness
Factors Affecting Acclimatization
• Age
• Fitness
• Medical conditions
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
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 doesn’t get better?
Cardiovascular Fitness Training
• Aerobic training
– Exercise at 60-70% of maximum heart rate
– Max HR=220-age
• Anaerobic training
– Exercise at 100% of max HR for a couple
minutes a few times a week
General Training
• Strength
– Free weight or machine work out
– All major muscle groups twice a week
• Flexibility
– End with stretching, e.g., Yoga
• Balance
Altitude Illness
Barometric pressure and altitude
Mt. Baldy
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Everest
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Altitude (m)
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Barometric pressure (mmHg)
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AMS
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 of AMS
• High intracranial pressure due to increased
leakage of fluid may possibly cause AMS
Mechanisms of AMS
• General fluid retention possibly via the reninangiotensin-aldosterone system or antidiuretic
hormone
What are the
Predictors of AMS?
Risk Factors for AMS
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Rapid ascent
Heavy exertion at altitude
Residence at sea level
Altitude, uncommon <7,500 ft
Hx of prior AMS
Young age (less common at age >50yrs)
• Physical fitness not protective
AMS Differential Diagnosis
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Dehydration
Hypothermia
Exhaustion
Hangover
Viral illness
Sedative or hypnotic medication
Carbon monoxide poisoning
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
Symptoms of Mild AMS
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Headache
Malaise
Anorexia
Low urine output
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Nausea/vomiting
Dizziness
Dyspnea on exertion
Dry cough
Inner chill
Any symptom of AMS should be
considered due to altitude
unless proven otherwise.
Headache is the most common.
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
Moderate AMS
• Ataxia
– Single most useful sign for deterioration
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Lassitude
Strange behavior
Confusion
Impaired judgement
Consciousness level   coma
Shortness of breath
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
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
HACE
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.
High Altitude Cerebral Edema
Treatment
• Descend!!
• Hyperbaric chamber
• Dexamethasone
HAPE
High Altitude Pulmonary Edema
(HAPE)
• Accounts for most deaths from high altitude
illness but uncommon (0.1-0.4% of
travelers >7,500 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
Clinical Presentation of HAPE
• Usually seen on 2nd night at altitude
• Dry cough, then frothy sputum, then bloodtinged sputum
• Crackly, rattlely breathing
• Rapid breathing
• Increased heart rate
• Cyanotic lips, face, fingernails
• Mild fever is common
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, antiasthma
• Special precautions in climbers with Hx of
HAPE
– Nifedipine
– Salmeterol
Treatment of HAPE
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Immediate descent mandatory
Supplemental oxygen
Hyperbaric therapy if available
Medication: Nifedipine, Diamox
• Mortality without medication- 50%
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
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 [?]
Coca
• South American locals chew coca leaves
• Exact mechanism not known
• Seems to be useful
Anti-Asthmatic Medication
• Seems to improve ventilation
• Long term studies still pending
– (what about asthmatics at altitude?)
Novel Approaches
• Levitra
• Cialis
• Viagra
PORTABLE HYPERBARIC CHAMBER
“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.
HAFE
high altitude flatus expulsion
• Expanding bowel gases at altitude
• Irritating to your partners