High Altitude Medicine

Veronika M. Bartova, M.D.

Medical advice

Recommendations

Before departure for expedition:• Routine medical check up (blood pressure

measuremet, ECG, routine biochemistry -namely blood glucose, cholesterol, blood count).

• Dentist check up. • Gynaecology check up for women.

Vaccination

Highly recommended• Typhoid vaccination

• Oral (tablets) - protection for up to 3 years, application at least 2 weeks before departure.

• Injection vaccine Typherix (GSK), oneinjection - protection for at least 3 years, application at least 2 weeks beforedeparture.

Vaccination

Hepatitis vaccination• Hepatitis A – inj Havrix (GSK), 1st dose (protects 1 yr),

2nd dose 6 to 12 mnths after 1st one, complete (2 doses) vaccination protects for 25 to 30 yrs.

• Hepatitis B – inj Engerix (GSK), 2 doses before departure, all 3 if possible; 2nd dose 1 mnth after 1st one and 3rd one5 mnths after the 2nd one. Complete (3 doses) vaccinationprotects for 25 to 30 yrs.

• Hepatitis A & B combined vaccine – inj Twinrix (GSK), 2 doses before departure, all 3 if possible; 2nd dose1 mnth after 1st one and 3rd one 5 mnths after 2nd one. Complete (3 doses) vaccination protects for 25 to 30 yrs.

Take care

• Radial keratotomy (myopia correction) canlead to refractive changes at altitude fromminor changes to severe disability.

• Increased risk of thrombotic events at highaltitude.– Oral contraceptives make this risk even higher.– Tight fitting socks (elastic bands) reduce blood

circulation and can also lead to thrombophlebitis.

Normal physiology

Definitions

• High altitude 1 500 – 3 500 m• Very high altitude 3 500 – 5 500 m• Extreme altitude above 5 500 m

• Zone of tolerance – individual, changes withacclimatisation.

• Acetazolamide (Diamox) is not recommendedas a routine drug before any ascent!!!

Normal reaction to altitude

• Hyperventilation during exertion• Shortness of breath during exertion,

resolving rapidly at rest• Changed breathing pattern at night

(Cheyne-Stokes)• Increased urination• Awakening at night• Weird dreams

Pulse & PaO2

• O2 in air at 5 500 m is 50 % of that at sea level.• Partial pressure of arterial oxygen.

At 4 200 m: 80 – 86 % normal acclimatized50 – 60 % with HAPE

If giving O2, saturate up to 99 – 100 %.

• Pulse oxymeter – easy and light monitoring device.

Puls at altitude increases by 20 beats per min at awakeningwithout acclimatization, returns to normal when acclimatized.

Altitude

• Human habitation ends at 5 400 m above sea level.• It is possible to stay at altitude over 6 000 m for weeks

or months, but organism starts to deteriorate.• Aim – acclimatize up to 6 500 m, above that it is just

tolerance, not acclimatization.• At high altitude risk of bacterial, not viral infection.

– Active immunity and B cell function is normal.– T cell function is impaired.

• No long term brain damage or intellectual impairmentafter repeated uncomplicated ascents to high altitude.

Nutrition & hydration

• Essential to keep good hydration at altitude.– Air at high altitude is dry, the fluid intake must be

increased compared to low altitude.– If no unusual fluid loss, the intake should be at

least 3 litres / 24 hrs up to 6 000 m.– Above 6 000 m fluid intake over 3 litres / 24 hrs.– Test – pale yellow urine colour.

• Diet should have > 70 % of energy fromcarbohydrates (pasta, rice, potatoes…).

High altitude medicaldisorders & diseases

Acute mountain sickness (AMS)

• Pathofysiology not fully understood.• Symptoms from brain swelling due to hypoxic stress.• AMS = headache + 1 of following symptoms:

– Loss of apetite, nausea, vomiting– Fatigue and/or weakness– Dizziness and/or lightheadedness– Difficulty sleeping– Staggering gait (unable to walk in straight line but normal

finger to nose test)– Confusion

(Spontaneously resolving headache after sufficientfluid intake is not AMS.)

Altitude disorders & diseases

• Dehydration & oedema• Diarrhoea• Cough; CO poisoning• Snow blindness• Frostbite• Hypothermia• High altitude cerebral edema (HACE)• High altitude pulmonary edema (HAPE)

Dehydration & oedema

• Dehydration increases the risk of headache &thrombotic complications.

• Extreme loss of fluid during activity in the sun athigh altitude .

• Peripheral oedema (face – puffy eyes, swollen feet) in absence of other symptoms of AMS can betreated with acetazolamide (Diamox) or other milddiuretic.

Diarrhoea

• Not always infectious aetiology – do not treat with ATB before trying other means(ATB can make it worse by killing thenormal intestinal bacteria).– Possible causes: dietary, stress, allergy,

medication).• Sufficient fluid and mineral intake – use

electrolyte supplements (mineral drinks).

Cough; CO poisoning

• Dry air leads to dry irritative cough(Khumbu cough) – carefull not to overlookbeginning HAPE.

• Carefull when cooking inside tents at highaltitude – let sufficient fresh air in to avoidCO poisoning.

• When cooking inside tent remove allinflamable materials from gas stove.

Snow blindness

• UV keratitis – damage caused by the UV light to the eye cornea with reactiveconjunctival inflammation.

• Blinding & painfull

• Resolves in 2 to 5 days; if serious, can leavepermanent damage.

Frostbite

• Local damage by low temperature• Enhanced by dehydration• Precaution

– Dry clothes & boots– Never ignore numbness (it may happen to be

the last sensation you´ve ever felt)– Use thin gloves for cooking, fotography…

• Never rub frostbitten area directly, defrostonly when further treatment is possible.

Hypothermia

• Overall damage by low temperature– Normal body temperature is 37 oC.– Decrease of body temperature < 37 oC leads to

shiverring.– With further decrease < 36,5 - 35 oC shivering

stops, dizziness, disorientation, pulse weak &slow – illusion of warmth, heart stops.

• Risk increased in strong wind, with hunger,dehydration, exhaustion.

Fatigue

• Increases the risk of possible– Complications (frostbite, dehydration, hypothermia)– Mistakes (falling into crevasses, stepping into the

void) – Bad judgement (distance & time estimation)

• Cannot be always avoided, but should alwaysbe remembered and precautions taken.

High Altitude Pulmonary Edema (HAPE)

• Fluid retention in the lung interstitial tissue, progressesinto fluid in the lung alveoli.– Signs & symptoms: fatigue, breathlesness at rest, cough,

pink sputum, fast and shallow breathing, blue lips and fingertips, gurgling sounds when breathing

• Never take HAPE for pneumonia, never treat with ATB at high altitude, always descend, then treat with ATB ifneeded.

• May culminate the 1st or 2nd night after ascent! In caseof any signs descend as fast & as low as possible.

• HAPE leads to extremely low PaO2, may be equal to rapid ascent & lead to progressive HACE.

High Altitude Cerebral Edema (HACE)

• Brain swelling due to hypoxia, alteration of all brainfunctions.– Signs & symptoms: change of mentation & ability to think,

agitation or lethargy, loss of coordination, ataxia (walking straight line is altered, touching the nose tip is not)

• Immediately descend as fast & as low as possible (atleast 500 – 1 000 m), never wait till morning at samealtitude – it may be too late in the morning!

• Treatment will help survive, but cannot match thepositive effect of descent.

Rescue

• Do not underestimate the risks even when “just” trekking.

• Always have an option to call help (cell phone, walkie-talkie).

• Be sure to have correct rescue phone numbers.• Do not hesitate to call for help – better quite

early than too late.• Have alternative treatment ready including

oxygen, possibly Gamow bag.

Golden rules

• It is OK to get altitude sickness. It is not OK to die from it.

• Any illness at altitude is altitude sicknessunless proven otherwise.

• Never ascend with symptoms of AMS.• If AMS is getting worse, descend at once.

Do not wait till morning.• Never leave someone with AMS alone.

Case studies

HACE – BiafoF 39 y, headache from alt of 3 000 m, improving at rest, slow ascent upto 4 150 m, where she looses coordination, feels extremely weak. Rescuehellicopter called at noon. Treatment with Diamox & Hydrocortison startedin camp at 4 pm. On treatment overnight, hellicopter cannot fly due to badweather in Skardu. From morning unconscious, i.v. infusion, bradycardiatreated by noradrenalin. Hellicopter arrived at 2 pm, she left with the lastinfusion bag. Given O2 on the way, dismissed from hospital after 24 hrswithout complications.

HACE – SpantikF 42 y, descending from C2 to C1 accompanied by 1 climber. Unable to continue due to „fatigue“ decided to stay between camps. Her friend left her alone & descended to C1 to bring help, which he had called by walkie-talkie. Two climbers returned to this place 3 hours later to find her lyingbetween 2 crevases, her backpack fallen into 1 of them. She was lying on the snow unconscious, no contact was possible. Then her heart stopped. Not even CPR brought her back to life. Her body remained at 5 431 m.

Medical kit

Personal medical kit

• Usual medication taken for any disorder, Antihistamines, Aspirin, Band aid, Elasticbandage, Pain killers, Paracetamol, Water purifying tbl.

• Multivitamin and mineral tbl and/or drinksare recommended.

Expedition medical kit

• Tablets: Antipyretics, analgetics, diarrhoea treatment, treatment for HAPE & HACE

• Antiinfectives: ATB, antivirotics, antiprotozoal (amoeba)• Injections & infusions: corticosteroids, antithrombotics,

analgetics, fluid replacement, treatment for HAPE & HACE• Eye drops & ointments: antiinfectives, corticosteroids, analgetics• Ointments & powder: antiinfectives, antimycotics, analgetics,

antithrombotics, antiflogistics• Varia: analgetic plaster, corticosteroid inhaler, antiemetics,

desinfection• Instruments, sutures, dressings: small surgical kit, syringes,

needles, splints, infusion sets• Oxygen as rescue treatment; Gamow bag

High Altitude MedicineMedical adviceRecommendationsVaccinationVaccinationTake careNormal physiologyDefinitionsNormal reaction to altitudePulse & PaO2 AltitudeNutrition & hydrationHigh altitude medical disorders & diseasesAcute mountain sickness (AMS)Altitude disorders & diseasesDehydration & oedemaDiarrhoeaCough; CO poisoningSnow blindnessFrostbiteHypothermiaFatigueHigh Altitude Pulmonary Edema (HAPE)High Altitude Cerebral Edema (HACE)RescueGolden rulesCase studiesMedical kitPersonal medical kitExpedition medical kit