altitude illness - oregon health & science university illness the pennington lectures, september...

Altitude Illness

The Pennington Lectures, September 16, 2016 Jason Yost, MD

Department of Family Medicine OHSU Cascades East Family Medicine

Objectives:

1. Recognize the common presentations of altitude illness

2. Identify patient risk factors for developing altitude illness

3. Teach the best ways to prevent altitude illness 4. List current recommendations for

pharmacological intervention for altitude illness

Case 1

Acute Mountain Sickness (AMS)

• ~6 to 12 hours after ascension to >2500 m (8000 ft)

• Typical symptoms include: – Headache

• Often accompanied by anorexia, nausea, dizziness, malaise, sleep disturbance


• Affects ~25% of unacclimatized persons who ascend to 2500 m (8000 ft)

• Increased altitude increases prevalence and severity of symptoms – 67% of climbers taking one to two days to reach

the summit of Mount Rainier (4392 m) experience AMS

https://en.wikipedia.org/wiki/Mount_Rainier#/media/File:Mount_Rainier_from_the_Silver_Queen_Peak.jpg


• High Altitude Cerebral Edema (HACE) is an extension of AMS characterized by neurological findings: – Ataxia, lethargy, confusion, altered mental status, – Leads to coma and eventually death


• AMS is characterized by: – Hypoventilation – Fluid retention and redistribution – Impaired gas exchange – Increased intracranial pressure – Possible endothelial cell dysfunction


• HACE is characterized by: – severe brain edema – hemorrhages and thromboses that are likely

secondary events

• HACE likely represents progression from the mild interstitial (vasogenic) edema of AMS to severe intracellular (cytotoxic) edema

Acute Mountain Sickness (AMS) • Major independent risk factors:

– history of acute mountain sickness – fast ascent – lack of previous acclimatization

• Other likely risk factors include: – female gender – < 50 years old – alcohol consumption – history of migraine

• Exercise may exacerbate acute mountain sickness, but good physical fitness is not protective


RISK CATEGORY DESCRIPTION PROPHYLAXIS

RECOMMENDATIONS

Low

• No prior history of altitude illness and ascending to less than 9,000 ft (2,750 m)

• More than 2 days to arrive at 8,200–9,800 ft (2,500–3,000 m), with subsequent increases in sleeping elevation less than 1,600 ft (500 m) per day, and an extra day for acclimatization every 3,300 ft (1,000 m)

Acetazolamide prophylaxis

generally not indicated.

Moderate

• Prior history of AMS and ascending to 8,200–9,100 ft (2,500–2,800 m) or higher in 1 day

• No history of AMS and ascending to more than 9,100 ft (2,800 m) in 1 day

• All people ascending more than 1,600 ft (500 m) per day (increase in sleeping elevation) at altitudes above 9,900 ft (3,000 m), but with an extra day for acclimatization every 3,300 ft (1,000 m)

Acetazolamide prophylaxis would be beneficial and

should be considered.

http://wwwnc.cdc.gov/travel/yellowbook/2016/the-pre-travel-consultation/altitude-illness


RISK CATEGORY DESCRIPTION PROPHYLAXIS

RECOMMENDATIONS

High

• History of AMS and ascending to more than 9,100 ft (2,800 m) in 1 day • All people with a prior history of HACE or HAPE • All people ascending to more than 11,400 ft (3,500 m) in 1 day • All people ascending more than 1,600 ft (500 m) per day (increase in

sleeping elevation) above 9,800 ft (3,000 m), without extra days for acclimatization

• Very rapid ascents (such as less than 7-day ascents of Mount Kilimanjaro)

Acetazolamide prophylaxis strongly

recommended.

http://wwwnc.cdc.gov/travel/yellowbook/2016/the-pre-travel-consultation/altitude-illness

Acute Mountain Sickness (AMS) MEDICATION INDICATION ROUTE DOSE

Acetazolamide

AMS, HACE prevention Oral 125 mg twice a day; 250 mg twice a day if >100 kg. Pediatrics: 2.5 mg/kg every 12 h

AMS treatment Oral 250 mg twice a day Pediatrics: 2.5 mg/kg every 12 h

Dexamethasone

AMS, HACE prevention Oral 2 mg every 6 h or 4 mg every 12 h Pediatrics: should not be used for prophylaxis

AMS, HACE treatment Oral, IV, IM

AMS: 4 mg every 6 h HACE: 8 mg once, then 4 mg every 6 h Pediatrics: 0.15 mg/kg/dose every 6 h up to 4 mg

Luks AM et al. 2015


• If it occurs: – Descend – Dexamethasone (preferable) – Oxygen – Portable hyperbaric chamber if decent not

possible


• Current recommendations from CDC for prevention of AMS: – Avoid going directly from low altitude to more than

2,750 m (9000 ft) sleeping altitude in 1 day – If acclimatized and > 2750 m (9000 ft), sleeping

elevation should not be increased by more than 500 m per day

– A rest day (ie, no ascent to higher sleeping elevation) every 3 to 4 days

– Avoid alcohol for the first 48 hours – High-altitude exposure at more than 9000 ft for >2

nights 30 days before the trip is helpful

Case 2

High Altitude Pulmonary Edema (HAPE)

• 1 per 10,000 skiers in Colorado • 1 per 100 climbers at more than 14,000 ft

(4,270 m) • Just as in AMS, increasing altitude increases

prevalence and severity of symptoms


• Initial symptoms are increased breathlessness, weakness, and cough

• Can quickly lead to severe pulmonary congestion, hypoxia, alveolar hemorrhage, and death


• The most likely mechanism is that hypoxia results in pulmonary hypertension and uneven pulmonary vasoconstriction

• May result in over-perfusion and “stress failure” of the capillary membrane in selected areas of the vascular bed


• Risk factors: – Previous episode of HAPE/AMS – Altitude – Rate of ascent – Time spent at altitude – Male gender – Cold ambient temperatures – Pre-existing respiratory infection – Vigorous exertion – Pre-exisiting cardio-pulmonary pathologies (primary

pulmonary hypertension, congenital absence of one pulmonary artery, and left-to-right intracardiac shunts)


• Prevention – Gradual ascent per AMS recommendations

• Pharmacologic prophylaxis usually reserved for patients with history of medical problems at high altitude or a history of pulmonary hypertension

MEDICATION INDICATION ROUTE DOSE

Nifedipine

HAPE prevention Oral 30 mg SR version every 12 h, or 20 mg SR version every 8 h

HAPE treatment Oral 30 mg SR version every 12 h, or 20 mg SR version every 8 h

Tadalafil HAPE prevention Oral 10 mg twice a day

Sildenafil HAPE prevention Oral 50 mg every 8 h

Salmeterol HAPE prevention Inhaled 125 μg twice a day

Luks AM et al. 2015


• If it occurs: – Descent – Oxygen – Nifedipine or possibly phosphodiesterase-5

inhibitors if nifedipine unavailable. – Portable hyperbaric chambers

Objectives:

1. Recognize the common presentations of altitude illness

2. Identify patient risk factors for developing altitude illness

3. Teach the best ways to prevent altitude illness 4. List current recommendations for

pharmacological intervention for altitude illness

References • Bartsch P, Swenson ER. Acute high-altitude illnesses. N Engl J Med. 2013 Oct 24;369(17):1666–7. • Hackett P. High altitude and common medical conditions. In: Hornbein TF, Schoene RB, editors. High Altitude: an

Exploration of Human Adaptation. New York: Marcel Dekker; 2001. p. 839–85. • http://wwwnc.cdc.gov/travel/yellowbook/2016/the-pre-travel-consultation/altitude-illness • Hultgren HN, Honigman B, Theis K, Nicholas D. High-altitude pulmonary edema at a ski resort. Western Journal of

Medicine. 1996;164(3):222-227. • Ingebretsen R et al. Advanced Wilderness Life Support. Edition 8.0. University of Utah: AdventureMed, LLC; 2013.

p. 53-59. • Larson EB, Roach RC, Schoene RB, Hornbein TF. Acute mountain sickness and acetazolamide. Clinical efficacy and

effect on ventilation. JAMA. 1982 Jul 16;248(3):328-32. PubMed PMID: 7045433. • Luks AM, Swenson ER. Medication and dosage considerations in the prophylaxis and treatment of high-altitude

illness. Chest. 2008 Mar;133(3):744–55. • Luks AM, McIntosh SE, Grissom CK, Auerbach PS, Rodway GW, Schoene RB, Zafren K, Hackett PH; Wilderness

Medical Society. Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update. Wilderness Environ Med. 2014 Dec;25(4 Suppl):S4-14. doi: 10.1016/j.wem.2014.06.017. PubMed PMID: 25498261.

• Maggiorini M, Brunner-La Rocca HP, Peth S, Fischler M, Bohm T, Bernheim A, et al. Both tadalafil and dexamethasone may reduce the incidence of high-altitude pulmonary edema: a randomized trial. Ann Intern Med. 2006 Oct 3;145(7):497–506.

• Pollard AJ, Niermeyer S, Barry P, Bartsch P, Berghold F, Bishop RA, et al. Children at high altitude: an international consensus statement by an ad hoc committee of the International Society for Mountain Medicine, March 12, 2001. High Alt Med Biol. 2001 Fall;2(3):389–403.

• Spark RF, Maher JT. Prevention of acute mountain sickness by dexamethasone. N Engl J Med. 1984 Mar 15;310(11):683–6.

http://www.ncbi.nlm.nih.gov/pubmed/7045433

Thank You!

Jason Yost [email protected] OHSU, Cascades East Family Medicine

mailto:[email protected]

altitude illness - oregon health & science university illness the pennington lectures, september...

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