title: High-altitude illnesses: physiology, risk factors, prevention, and treatment.
abstract: High-altitude illnesses encompass the pulmonary and cerebral syndromes that occur in non-acclimatized individuals after rapid ascent to high altitude. The most common syndrome is acute mountain sickness (AMS) which usually begins within a few hours of ascent and typically consists of headache variably accompanied by loss of appetite, nausea, vomiting, disturbed sleep, fatigue, and dizziness. With millions of travelers journeying to high altitudes every year and sleeping above 2,500 m, acute mountain sickness is a wide-spread clinical condition. Risk factors include home elevation, maximum altitude, sleeping altitude, rate of ascent, latitude, age, gender, physical condition, intensity of exercise, pre-acclimatization, genetic make-up, and pre-existing diseases. At higher altitudes, sleep disturbances may become more profound, mental performance is impaired, and weight loss may occur. If ascent is rapid, acetazolamide can reduce the risk of developing AMS, although a number of high-altitude travelers taking acetazolamide will still develop symptoms. Ibuprofen can be effective for headache. Symptoms can be rapidly relieved by descent, and descent is mandatory, if at all possible, for the management of the potentially fatal syndromes of high-altitude pulmonary and cerebral edema. The purpose of this review is to combine a discussion of specific risk factors, prevention, and treatment options with a summary of the basic physiologic responses to the hypoxia of altitude to provide a context for managing high-altitude illnesses and advising the non-acclimatized high-altitude traveler.
authors.affiliation: Department of Radiology, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Taylor
keywords: Acute mountain sickness; acetazolamide; high-altitude cerebral edema; high-altitude pulmonary edema
references.citation: JAMA. 2002 May 1;287(17):2228-35
references.pmid: 11980523
references.citation: Aviat Space Environ Med. 1994 Jan;65(1):19-20
references.pmid: 8117220
references.citation: West J Med. 1986 May;144(5):569-73
references.pmid: 3716417
references.citation: High Alt Med Biol. 2008 Winter;9(4):271-9
references.pmid: 19115910
references.citation: N Engl J Med. 1991 Oct 31;325(18):1284-9
references.pmid: 1922223
references.citation: High Alt Med Biol. 2002 Winter;3(4):361-76
references.pmid: 12631422
references.citation: High Alt Med Biol. 2001 Fall;2(3):389-403
references.pmid: 11682018
references.citation: Aviat Space Environ Med. 1983 Dec;54(12 Pt 1):1063-73
references.pmid: 6661120
references.citation: J Appl Physiol Respir Environ Exerc Physiol. 1983 Sep;55(3):678-87
references.pmid: 6415007
references.citation: Circulation. 2001 Apr 24;103(16):2078-83
references.pmid: 11319198
references.citation: Eur Respir J. 2007 Apr;29(4):770-92
references.pmid: 17400877
references.citation: JAMA. 1998 Dec 9;280(22):1920-5
references.pmid: 9851477
references.citation: Ann Intern Med. 1993 Apr 15;118(8):587-92
references.pmid: 8452324
references.citation: High Alt Med Biol. 2007 Spring;8(1):27-31
references.pmid: 17394414
references.citation: Chest. 2008 Aug;134(2):402-416
references.pmid: 18682459
references.citation: JAMA. 2002 May 1;287(17):2275-8
references.pmid: 11980529
references.citation: High Alt Med Biol. 2000 Winter;1(4):331-6
references.pmid: 11256469
references.citation: Med Sci Sports Exerc. 2002 Dec;34(12):1886-91
references.pmid: 12471292
references.citation: BMJ. 1990 Oct 13;301(6756):853-5
references.pmid: 2282425
references.citation: Circulation. 1964 Mar;29:393-408
references.pmid: 14131411
references.citation: High Alt Med Biol. 2005 Winter;6(4):273-5
references.pmid: 16351559
references.citation: High Alt Med Biol. 2005 Summer;6(2):189-90
references.pmid: 16060854
references.citation: High Alt Med Biol. 2008 Winter;9(4):265-9
references.pmid: 19115909
references.citation: High Alt Med Biol. 2008 Summer;9(2):158-66
references.pmid: 18578647
references.citation: High Alt Med Biol. 2007 Fall;8(3):184-91
references.pmid: 17824818
references.citation: High Alt Med Biol. 2008 Summer;9(2):148-57
references.pmid: 18578646
references.citation: Wilderness Environ Med. 2009 Winter;20(4):311-7
references.pmid: 20030437
references.citation: Chest. 2008 Sep;134(3):613-622
references.pmid: 18779196
references.citation: High Alt Med Biol. 2008 Winter;9(4):311-7
references.pmid: 19115916
references.citation: High Alt Med Biol. 2002 Summer;3(2):177-93
references.pmid: 12162862
references.citation: Wilderness Environ Med. 2004 Fall;15(3):198-201
references.pmid: 15473460
references.citation: J Appl Physiol (1985). 2005 Feb;98(2):591-7
references.pmid: 15501929
references.citation: High Alt Med Biol. 2003 Spring;4(1):45-52
references.pmid: 12713711
references.citation: High Alt Med Biol. 2007 Summer;8(2):139-46
references.pmid: 17584008
references.citation: High Alt Med Biol. 2010 Winter;11(4):325-32
references.pmid: 21190501
references.citation: J Appl Physiol (1985). 2000 Feb;88(2):581-5
references.pmid: 10658026
references.citation: Eur J Neurol. 2008 Oct;15(10):1050-7
references.pmid: 18717724
references.citation: N Engl J Med. 2003 Oct 23;349(17):1628-35
references.pmid: 14573734
references.citation: Aviat Space Environ Med. 2006 Jul;77(7):742-4
references.pmid: 16856361
references.citation: Am Rev Respir Dis. 1978 Nov;118(5):909-39
references.pmid: 216294
references.citation: Arch Neurol. 2005 Mar;62(3):433-7
references.pmid: 15767508
references.citation: Ann Emerg Med. 1991 Oct;20(10):1109-12
references.pmid: 1928883
references.citation: JAMA. 1986 Jul 4;256(1):81-2
references.pmid: 3520035
references.citation: N Engl J Med. 1989 Dec 21;321(25):1707-13
references.pmid: 2687688
references.citation: High Alt Med Biol. 2004 Fall;5(3):335-40
references.pmid: 15453999
references.citation: Am J Respir Crit Care Med. 2005 Feb 1;171(3):275-81
references.pmid: 15516532
references.citation: Wilderness Environ Med. 2004 Summer;15(2):121-4
references.pmid: 15228066
references.citation: N Engl J Med. 2009 Jan 8;360(2):140-9
references.pmid: 19129527
references.citation: High Alt Med Biol. 2004 Summer;5(2):180-9
references.pmid: 15265339
references.citation: Sports Med. 1994 May;17(5):309-23
references.pmid: 8052768
references.citation: High Alt Med Biol. 2008 Summer;9(2):111-4
references.pmid: 18578641
references.citation: High Alt Med Biol. 2009 Spring;10(1):25-32
references.pmid: 19326598
references.citation: J Appl Physiol (1985). 2010 Dec;109(6):1792-800
references.pmid: 20864559
references.citation: Lancet. 1976 Nov 27;2(7996):1177-9
references.pmid: 63001
references.citation: High Alt Med Biol. 2005 Summer;6(2):158-66
references.pmid: 16060850
references.citation: J Appl Physiol (1985). 1999 Dec;87(6):1997-2006
references.pmid: 10601141
references.citation: High Alt Med Biol. 2008 Spring;9(1):15-23
references.pmid: 18331216
references.citation: High Alt Med Biol. 2008 Spring;9(1):89-95
references.pmid: 18331224
references.citation: High Alt Med Biol. 2009 Spring;10(1):1-2
references.pmid: 19278346
references.citation: Lancet. 1995 Jul 22;346(8969):254-5
references.pmid: 7616830
references.citation: N Engl J Med. 2001 Jul 12;345(2):107-14
references.pmid: 11450659
references.citation: High Alt Med Biol. 2008 Winter;9(4):281-7
references.pmid: 19115911
references.citation: J Physiol. 1964 Mar;170:344-54
references.pmid: 14165170
references.citation: High Alt Med Biol. 2008 Spring;9(1):53-62
references.pmid: 18331221
references.citation: Eur Respir J. 1998 Dec;12(6):1242-7
references.pmid: 9877470
references.citation: High Alt Med Biol. 2010 Spring;11(1):19-25
references.pmid: 20367484
references.citation: High Alt Med Biol. 2010 Spring;11(1):69-72
references.pmid: 20367491
references.citation: Ann Intern Med. 2006 Oct 3;145(7):497-506
references.pmid: 17015867
references.citation: N Engl J Med. 2002 Jul 4;347(1):43-53
references.pmid: 12097540
references.citation: High Alt Med Biol. 2008 Summer;9(2):140-7
references.pmid: 18578645
references.citation: Eur Respir J. 1991 Jan;4(1):115-9
references.pmid: 2026231
references.citation: Br Med J (Clin Res Ed). 1987 May 30;294(6584):1380-2
references.pmid: 3109663
references.citation: West J Med. 1995 Aug;163(2):117-21
references.pmid: 7571557
references.citation: High Alt Med Biol. 2006 Spring;7(1):17-27
references.pmid: 16544963
references.citation: J Appl Physiol (1985). 2007 Apr;102(4):1313-22
references.pmid: 17023566
references.citation: High Alt Med Biol. 2007 Winter;8(4):278-85
references.pmid: 18081503
references.citation: High Alt Med Biol. 2008 Winter;9(4):301-6
references.pmid: 19115914
references.citation: High Alt Med Biol. 2010 Winter;11(4):307-8
references.pmid: 21190496
references.citation: Ann Intern Med. 2004 Nov 16;141(10):789-800
references.pmid: 15545679
references.citation: High Alt Med Biol. 2005 Spring;6(1):43-9
references.pmid: 15772499
references.citation: Am J Med. 2006 Feb;119(2):168.e1-6
references.pmid: 16443427
references.citation: Neuropsychol Rev. 2004 Dec;14(4):197-224
references.pmid: 15796116