High-altitude medicine.
Sojourns to high altitude have become common for recreation and adventure purposes. In most individuals, gradual ascent to a high altitude leads to a series of adaptive changes in the body, termed as acclimatization. These include changes in the respiratory, cardiovascular, hematologic systems and cellular adaptations that enhance oxygen delivery to the tissues and augment oxygen uptake. Thus there is an increase in pulmonary ventilation, increase in diffusing capacity in the lung, an increase in the cardiac output and increase in the red blood cell count due to an increase in erythropoietin secretion by the kidney, all of which enhance oxygen delivery to the cells. Cellular changes like increase in the number of mitochondria and augmentation of cytochrome oxidase systems take months or years to develop. Too rapid an ascent or inability to acclimatize leads to high-altitude illnesses. These include acute mountain sickness (AMS), high-altitude cerebral edema (HACE) and high-altitude pulmonary edema (HAPE). Acute mountain sickness is self limiting if recognized early. Both HACE and HAPE are life threatening and need to be treated aggressively. The key to treatment of these illnesses is early recognition; administration of supplemental oxygen; and descent if required. Drugs like acetazolamide, dexamethasone, nifedipine may be administered as recommended.
Paralikar
Swapnil J
SJ
Department of Physiology, Medical College, Baroda, India.
Paralikar
Jagdish H
JH
Aviat Space Environ Med. 1988 Oct;59(10):950-4
3190622
JAMA. 1998 Dec 9;280(22):1920-5
9851477
Chest. 2008 Aug;134(2):402-416
18682459
J Appl Physiol (1985). 1987 Aug;63(2):521-30
3654410
J Appl Physiol (1985). 2004 Jul;97(1):149-59
15004003
JAMA. 1986 Jul 4;256(1):81-2
3520035
Am J Physiol Heart Circ Physiol. 2004 Mar;286(3):H856-62
14604853
Adv Exp Med Biol. 2001;502:419-37
11950154
N Engl J Med. 1991 Oct 31;325(18):1284-9
1922223
J Appl Physiol (1985). 2005 Mar;98(3):1101-10
15703168
Crit Care Med. 2003 Apr;31(4):1183-9
12682491
N Engl J Med. 1960 Sep 8;263:478-80
14403413
N Engl J Med. 1965 Jul 8;273:66-73
14301200
Med Sci Sports Exerc. 2002 Dec;34(12):1928-33
12471298
J Appl Physiol (1985). 1987 Jul;63(1):3-11
3305469
Am J Cardiol. 1987 Jul 1;60(1):137-42
3604926
High Alt Med Biol. 2004 Summer;5(2):180-9
15265339
J Am Coll Cardiol. 2000 Mar 15;35(4):980-7
10732898
J Appl Physiol (1985). 2000 Apr;88(4):1474-80
10749844
Am Rev Respir Dis. 1978 Mar;117(3):455-64
629480
J Appl Physiol (1985). 1991 Apr;70(4):1731-42
2055852
High Alt Med Biol. 2004 Summer;5(2):147-55
15265336
Crit Care Clin. 1999 Apr;15(2):265-80, viii
10331128
News Physiol Sci. 2003 Apr;18:55-9
12644620
Wilderness Environ Med. 2004 Spring;15(1):32-7
15040504
Lancet. 1965 Jan 30;1(7379):229-34
14238062
Ann Intern Med. 2003 Aug 19;139(4):253-7
12965980