Dumont, L., et al, Br Med J 321(7256):267, July 29, 2000
METHODS: This systematic review, from the University of Geneva in Switzerland, evaluated 33 randomized, placebo-controlled trials of pharmacologic prophylaxis of acute mountain sickness (AMS), in which 523 subjects received one of 13 interventions and 519 controls received placebo.
RESULTS: At altitudes above 4,000m (13,000 feet), AMS developed in 67% of controls. Acetazolamide was effective in preventing AMS at a dose of 750mg (relative risk [RR 2.2), while the commonly used 500mg dose was not effective Dexamethasone at a dose of 8-16mg was also effective (RR 2.5 Common adverse effects included depression after dexamethasone, and paresthesias and polyuria with acetazolamide. There was insufficient evidence to support a benefit of the eleven other interventions (including dihydroxyaluminum sodium, nifedipine spironolactone, ginkgo biloba, aspirin, codeine, phenformin furosemide, phenytoin and antidiuretic hormone). For both acetazolamide and dexamethasone, there was a direct relationship between the rate of ascent and efficacy. The number needed to treat to prevent AMS was high when the ascent rate was low, but remained relatively constant at 2-3 at ascent rates exceeding 500m/day (1600 ft/day).
CONCLUSIONS: Acetazolamide (750mg) and dexamethasone (8-16mg) appear to prevent AMS associated with ascent to altitudes exceeding 4,000m at a rate greater than 500m/day Dexamethasone may be associated with more frequent serious adverse events. A 500mg dose of acetazolamide does not appear to be more effective than placebo. Pharmacologic prophylaxis of AMS does not appear to be warranted at an ascent rate of less than 500m/day R4 – J3
gingko does not work, acetazolamide does (BMJ Saturday 03 April 2004)
Ibuprofen works 600 mg 6 hrs prior to ascent and then (Ann Emerg Med 2012;59:484)
Acute Mountain Sickness (AMS)
onset in a few hours, lasts 3-4 days
rare below 8000 feet
headache, anorexia, n / v, and difficulty sleeping. Worsened by valsalva and stooping forward.
From hypoxia during sleep
Halt ascent for 12-36 hours to allow acclimatization.
Diamox 250 mg PO TID should also be used.
causes renal bicarbonate diuresis this results in acidosis and then resp hyperventilation
Dexamethasone 4 mg QID also helps but may have side effects.
High Altitude Pulmonary Edema (HAPE)
NCPE
1-4 days after ascent and often preceded by exertion
Descent, BiPAP, Oxygen, and Bedrest.
Dex does not work
Temporizing measures until descent include: portable hyperbaric chamber and nifedipine.
High Altitude Cerebral Edema (HACE)
Dexamethasone, oxygen, and stat descent.
high-altitude illness (NEJM 345:2 July 12, 2001) physical fitness is not protective acute mountain sickness: presence of a HA in an unacclimated pt who has recently arrived at an altitude above 2500 m plus one or more of gi sx, insomnia, dizziness, lassitude, or fatigue. HACE: defined as onset of ataxia, altered consciousness or both in an AMS pt. will not usually present as focal findings but instead as global encephalopathy. Usually progresses from drowsiness to stupor. seizures are rare. they die of brain herniation AMS HACE rx: first stop ascent until sx resolve, if no response to med treatment, pt should progress to lower altitude. a descent of only 500-1000 m usually is enough to cause resolution. Acetazolamide (125-250 bid for prevent, 250 for rx). Dex is at least equally as effective (4mg q 12 for prevent, 4 mg po q6 for rx of all but HAPE) a single dose of ibuprofen may also cause resolution of high altitude headache can give ambien for insomnia as it will not depress ventilations for prevention, gradual ascent (600 m per day above 2500 m) Ginkgo biloba prevented mountain sickness up to 5000 m. 80-120 mg bid HAPE rales typically originate in the r axilla and become bilat fever up to 38.5 is common NCPE Giving physostigmine dilute 1mg with 9 cc saline. give 1 cc q 30 sec over 5 min if nothing, give 2nd mg
From: thomas.marx@medizin.uni-ulm.de Subject: Re: [ccm-l] peru and mountain sickness X-Originating-IP: 134.60.112.134 Sender: ccm-l-bounces@ccm-l.org To: Brian Woodcock <bwudcock@med.umich.edu> Cc: cotton.chris@saambulance.com.au, KMATTOX@aol.com, ccm-l@ccm-l.org X-BeenThere: ccm-l@ccm-l.org User-Agent: Internet Messaging Program (IMP) 3.2.5 X-PMAS-Software: PreciseMail V2.0-1 [050428] (ing-1.mssm.edu) X-PMAS-Allowed: Message allowed by user rule X-Mailman-Version: 2.1.5 List-Post: <mailto:ccm-l@ccm-l.org> List-Subscribe: <http://www.ccm-l.org/mailman/listinfo/ccm-l>, <mailto:ccm-l-request@ccm-l.org?subject=subscribe> List-Unsubscribe: <http://www.ccm-l.org/mailman/listinfo/ccm-l>, <mailto:ccm-l-request@ccm-l.org?subject=unsubscribe> List-Archive: <http://ccm-l.org/pipermail/ccm-l> List-Help: <mailto:ccm-l-request@ccm-l.org?subject=help> List-Id: International Critical Care Internet Group <ccm-l.ccm-l.org> Original-recipient: rfc822;scott.weingart@mssm.edu >From Nepal with love (they should know what they are talking about): Prevention of Altitude Illness: 1. Having a sensible itinerary is the most important way to avoid altitude illness. It is recommended to climb not more than 1000ft (300m) a day above an altitude of 10,000 ft (3000m). If the terrain is such that this is not possible, one needs to have two rest days e.g. 2 rest days are recommended at Namche Bazaar where 2000ft (600m) are gained in 1 day from Phakding for most itineraries. Having flexibility with 1-2 extra days built into your schedule will allow you to rest when you are not feeling well and help avoid altitude illness. It also helps to ‘climb high’ and ‘sleep low’. 2. Use of Diamox- Diamox blocks an enzyme in the kidney and makes the blood acidic which is interpreted by the brain as a signal to breathe more. Diamox therefore, enhances the physiological response to altitude by increasing the rate and depth of breathing and it also acts as a mild diuretic. Side effects of the drug are: tingling of fingers and toes and tingling around mouth. Sulfa allergic individuals are recommended not to take this drug. Prophylactic dose of Diamox is half or one 250mg tablet twice a day. Use of Diamox will not mask the symptoms of altitude illness if it is to occur. Start taking Diamox the day before ascent to 10,000 ft (3000m), continue it through your ascent to higher altitudes and stop when you start descending. 3. Other preventive strategies: Gingko Biloba at dosage of 60mg three times a day started 5 days before ascent has been found useful in preventing altitude illness. This may be an alternative for Sulpha allergic people but it has been found to be less effective than diamox. Salmeterol (Serevent) inhaler used to treat asthma can help prevent HAPE and may be used by HAPE susceptible people prophylactically. Treatment: For mild symptoms, one can stay at the same altitude to see if symptoms will resolve and ascend when symptoms have resolved completely. Diamox can also be used to treat mild-moderate symptoms. If symptoms persist or worsen at this altitude, descent is required. For severe symptoms i.e. HACE or HAPE, descent must begin immediately whenever feasible. Helicopter evacuation may be essential for descent unless there is rapid improvement with medical treatment and walking down is feasible. Physical exertion even when it is for descent can be detrimental for patients with HAPE. Severe HAPE patients should be carried down if helicopter evacuation is not possible. Other treatment modalities to help through during descent- 1. Diamox-. Dosage: One 250 mg tablet two or three times a day. This is generally useful for mild-moderate AMS. 2. Dexamethasone- very potent steroid. Used in High Altitude Cerebral Edema or HACE temporarily to facilitate descent. This drug improves the symptoms without improving acclimatization. It is not recommended to ascend while still taking this drug. Dosage: 4 mg every 6 hours. 3. Nifedipine- useful in HAPE by lowering pressure in the pulmonary blood vessels and thereby decreasing fluid in the lungs. Dosage: 10 mg three or four times a day. This drug also lowers blood pressure. 4. Oxygen – very useful particularly for HAPE. Gamow Bag – This is a portable bag which, when inflated, converts into a high pressure bag in which an individual with severe symptoms of HACE or HAPE is put and air is pumped in with a foot-pump. Pressure created inside the bag increases the oxygen tension and a person can improve rapidly. This is used to tie a person over an acute crisis before descent is possible or pending helicopter evacuation. This bag is found in the Manang and Pheriche Himalayan Rescue Association Aid Posts, at Kunde Hospital and at several other locations in the Everest region . Many groups that trek to high altitudes in remote places are nowadays taking this bag with them. These can be rented in Kathmandu or overseas. Three golden rules to avoid dying from altitude illness: 1. Learn the early symptoms of altitude illness and recognise when you have them. Remember, you may be the only person in a group with symptoms. 2.Never ascend to sleep at a new altitude with any symptoms of AMS. 3. Descend if your symptoms are getting worse while resting at the same altitude. Ciwec Clinic Nepal
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