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altitude sickness

Also see high altitude periodic breathing. Etiology: - modifiable risk factors - higher destination altitude - faster rate of ascent - comorbid risk facors - cardiopulmonary disease - hemoglobinopathy - sickle cell disease & sickle cell trait Epidemiology: - elevations above 2500 meters (8200 feet) - young age & level of physical fitness not protective Pathology: - hypobaric hypoxia* - hypoxia-induced hyperventilation diminishs PaCO2 towards the apneic threshold - this decreases respiratory rate with resultant rise in PaCO2, increased respiratory drive & recurrent hyperventilation - high-altitude periodic breathing ensues unless the cycle is broken * atmospheric oxygen remains at 21% but barometric pressure diminishes amount of oxygen available [2] Management: - descent to a lower altitude is curative - gradual ascent - spend one night at an intermediate altitude - supplemental oxygen - acetazolamide accelerates acclimatization by inducing a slight metabolic acidosis stimulating ventilation [5] - nifedipine for high-altitude pulmonary edema - dexamethasone for severe acute mountain sickness & cerebral edema (also descent to lower elevation) [2]

Related

Cheyne-Stokes respiration (includes: high altitude periodic breathing)

Specific

acute mountain sickness chronic mountain sickness (Monge's disease) high-altitude cerebral edema (HACE) high-altitude pulmonary edema

General

lower respiratory tract disease environmental exposure

References

  1. Schoene RB. Illnesses at high altitude. Chest. 2008 Aug;134(2):402-16 PMID: 18682459
  2. Medical Knowledge Self Assessment Program (MKSAP) 17, 18, American College of Physicians, Philadelphia 2015, 2018.
  3. West JB; American College of Physicians; American Physiological Society. The physiologic basis of high-altitude diseases. Ann Intern Med. 2004 Nov 16;141(10):789-800. Review. PMID: 15545679
  4. Luks AM, Swenson ER, Bartsch P. Acute high-altitude sickness. Eur Respir Rev. 2017 Jan 31;26(143). pii: 160096. Review. PMID: 28143879 Free Article
  5. Furian M, Mademilov M, Buergin Aet al. Acetazolamide to prevent adverse altitude effects in COPD and healthy adults. NEJM Evidence 2022 Jan; 1:EVIDoa2100001. PMID: 38296630 https://evidence.nejm.org/doi/10.1056/EVIDoa2100006