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An Approach To Counselling Travellers Going To AltitudeGary Podolsky MD
Objectives: • To introduce clinicians to common problems that will affect patients altitude • Describe the pathophysiology processes that cause the spectrum of common altitude illnesses • To advocate protective strategies and medications to prevent, alleviate or treat high altitude illnesses for athletes
Case study: A 60 year physician who had ascended Everest three previous times without oxygen recently experienced severe headache, fatigue, and lassitude which he attributed to altitude illness. He wishes to go on another mountaineering expedition and is requesting medical clearance and advice.
Illness at AltitudeTravellers to areas of high altitude >2400m (>8000ft) may be at risk of altitude illnesses. Clinicians and travellers need to understand common altitude maladies. Family practitioners may be called upon to advise prospective travellers to altitude with specialized advice and medications to prevent illness.
Acute Mountain Sickness (AMS) symptoms include headache, nausea, vomiting, disturbed sleep and swollen ankles. Usually symptoms subside after a day or two but also may rarely progress to serious problems.
High Altitude Cerebral Edema (HACE) symptoms include difficulty walking, staggering as if drunk and decreased finger coordination (early). Confusion and visual and auditory hallucinations also may occur with insidious progression to coma and death.
High Altitude Pulmonary Edema (HAPE) symptoms include shortness of breath even at rest, an irritable cough that produces a pink frothy sputum, and a staggering drunk walk may occur. Early warning symptoms include anxiety, restlessness, increased pulse, quick shallow breathing and a slight fever.
Many victims deny early symptoms while subtle and are unprepared when the disease is advanced. These clinical entities may occur in healthy adults who had previously had no prior difficulties at altitude. They are more likely in those with sudden changes in altitude.
Other Altitude illnesses exist but are beyond the scope of this introduction.
AcclimatizationSuccessful acclimatization to the lowered oxygen content at altitude starts with hyperventilation and involves a series of adaptations to maintain oxygenation ultimately to the level of the mitochondria . 1, 2 (table 1) . Trips involving sudden altitude changes may overwhelm these processes of adaptation in healthy individuals. Any pre-morbid process that impairs these series of adaptative mechanisms may lead to a failure to acclimate.
Screening Travellers for AltitudeScreening for high-risk individuals that may do poorly or decompensate at altitude starts with looking at each condition and how it may be affected by altitude.
Some conditions are well described to cause problems and may be absolute or relative contraindications for altitude while other concerns such as age and uncomplicated pregnancies are not contraindications 3 (table 2). Individuals with relative contraindications may still be counselled to ascend slowly and use medication if appropriate.
A recent international consensus has also determined that children also develop altitude illnesses. 4 Slow progress to altitude permits time to acclimate. Even if an individual has impairment in some of their adaptative processes extra time allows for other mechanisms to compensate.
Education of Attitude TravellersTravellers should be educated on the insidious symptoms of altitude and be prepared to change their travel plans by either or seeking appropriate aid 5 or by descending. Other concerns such as remoteness of medical care, feasibility of evacuations and physical environment (hypothermia) are also relevant in the counselling of these patients.
Altitude MedicationRecent literature has examined the use of medications to prevent and treat altitude illnesses.
Diamox (Acetazolamide) is a carbonic anhydrase inhibitor and diuretic. It speeds up acclimation by hastening a bicarbonate diuresis speeding up the normal renal metabolic acidosis response to altitude. It is used as a preventative medication at 125mg bid starting one-day prior and after ascent. To prevent periodic breathing 125mg is recommended before sleep. At these doses there is not a prolonged diuresis. Higher doses of 250mg bid are more associated with diuresis and paresthesia to fingertips. Diamox also alters the taste sensation for carbonated beverages.
Diamox contains a sulfaryl group and may be considered even in those with sulphonamide allergies Diamox may help resolve AMS although this is not as effective as preventing AMS Diamox at 250mg twice per day (adults), 5mg/kg/day children may be used to treat HAPE.
Dexamethasone ( Decadron) dosed at 4mg q6-12hrs has been used for those with HACE as a temporising measure prior to transfer. Decadron has been proposed for use in those unable to take diamox but who must ascend quickly. As a prophylactic drug Decadron suppresses symptoms but does not aid acclimation and is dangerous to use in untrained individuals as altitude illnesses will rebound after the drug's effect ears off. 6
Gingko biloba has been advocated for prevention of AMS but recent studies de-emphasise this. Its use has also been associated with cerebral bleeds. 7 (Category 3)
Nifedipine has been used to both to treat HAPE patients (10mg once followed by 20-30mg extended release tablets 2-3 times daily) and as a prophylaxis (20mg slow release every 8 hrs) for known HAPE sensitive individuals on re-exposure to altitude. It is not effective in preventing AMS or HACE.
Furosemide is not effective in HAPE as HAPE is from an exudate not a transudate. HAPE victims may already be intravascularly dehydrated and although tempting to use it will deplete their intravascularly volume. Small doses may be used for treating mild peripheral edema that is occasionally associated with mild AMS.
Morphine IV may improve the perfusion in HAPE and should be used in small doses to watch for respiratory depression, a decreased cognition in HACE. Ginger, and Coco leaves (cocaine) and other homeopathic treatments are not recommended for altitude prevention (Category 1).
ASA for prevention of thromboses has been recommended for those with higher risks of thrombosis including polycythemia from altitude (Category 3). Its role for healthy young adults and a suggested low dose of 81mg every day has been suggested (Category 1) 5 .
Sildenafil (Viagra) and the other long acting erectile drugs have been shown as potent pulmonary vasodilators and could have a therapeutic use in the prevention and treatment of altitude illness (Category 1 although this is under investigation through several studies).
Salbutamol (Ventolin) and other beta agonists are being studied for their use in prevention and treatment of HAPE. (Category 1)
In response to this case: Our client is a physician knowledgeable in the signs and symptoms and quite qualified to carry and administer medication on behalf of himself and his expedition. Physicians are however frequently victims themselves at altitude despite their training. However our client has had experience in both medicine and altitude.
He was prescribed Diamox 125mg BID for prevention of altitude illness with instructions to increase to 25omg with symptoms of mild to moderate AMS and rest.
His prescription is above the dose (125mg at night) for periodic breathing as well.
He was informed of gingko biloba and counselled not to take that or nor coco leaves nor ginger as evidence in there use is lacking 7 (Category 3).
He did not have symptoms of HAPE and does not need Nifedipine prophylactically but was given prescription to treat his team if necessary. Decadron was also prescribed as an emergency treatment drug for use in severe AMS/ HACE situations.
Other suggestions for his medical kit included salbutamol inhalers for HAPE as well as campfire stove bronchitis, and ASA 81mg for prevention of thrombosis.
Sidinafel was discussed as a possible useful preventative agent but final studies although hopeful are not yet finished to justify its recommendation (Category 1 evidence).
Finally our patient was counselled to have everyone in the expedition including porters knowledgeable in the signs and symptoms of altitude illness and to discuss with the expedition leaders and tour operators a written plan of action of how to properly evacuate anyone who requires descent early in the evolution of any problem. Conclusion
Travel to altitude is becoming increasingly common and family practitioners will be asked to medically evaluate patients. It is important to understand and anticipate common problems at altitude. Screening potential high-risk patients is essential but educating all high altitude visitors on problems they may encounter as well as effective ways to deal with them is important. Medications for self-treatment and prevention of illness may be appropriate for specific patients
References :
1.Disorders Caused by Altitude Hackett, P, Houston C, Hutgren H Wilderness Medicine 101 Published by the Wilderness Medicine Society Colorado Springs 2004 www.wms.org 2.Hackett P. Roach RC. High Altitude Illness N England J Med 2001; 345: 107-114
3.Dietz T, Hackett P Altitude In: Keystone J ed. Travel Medicine New York Mosby 2004: 363-373.
4.Pollard AJ, Niermeyer S, et al. (2001) Children at High Altitude: An International Consensus Statement by an Ad Hoc Committee of the International Society for Mountain Medicine, March 12,2001. High Altitude Medicine & Biol 2:389-403.
5.Altitude Illness Prevention and Treatment Stephen Bezruchka, M.D Published by the Mountaineers Seattle Washington 1994.
6.Hackett PH, Roach RC, Wood RA, et al: Dexamethasone for prevention and treatment of acute mountain sickness. Aviat Space Environ Med 1998;59:950-954. 7.Randomised, double blind, placebo-controlled comparison of ginkgo biloba and Acetazolamide for prevention of acute mountain sickness among Himalayan trekkers: the prevention of high altitude illness trial (PHAIT) BMJ 2004; 328:798(3 April).
Table 2 Medical Conditions and Altitude (up to 3000m)
Dietz T, Hackett P Altitude In: Keystone J ed. Travel Medicine New York Mosby 2004: 363-373.
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