Epidemiology

• Occurs in High-Altitude Dwellers
• Incidence in Andean Countries: 5-15% of the population residing >3200m (10,500 ft)
  • Chronic Mountain Sickness Affects Approximately 2 Million People

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Physiology

• Chronic High Altitude-Related Disease (see High Altitude, [[High Altitude]])
  • Chronic Hypobaric Hypoxia
  • Increased Erythropoietin Production (see Serum Erythropoietin, [[Serum Erythropoietin]])

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Diagnosis

Complete Blood Count (CBC) (see Complete Blood Count)

• Polycythemia: hemoglobin >21 g/dL or hematocrit >63%

Arterial Blood Gas (ABG) (see Arterial Blood Gas)

• Hypoxemia (see Hypoxemia)

Echocardiogram (see Echocardiogram, [[Echocardiogram]])

• Findings
  • Pulmonary Hypertension (see Pulmonary Hypertension, [[Pulmonary Hypertension]])

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Clinical Manifestations

Cardiovascular Manifestations

Right-Sided Congestive Heart Failure (CHF) (see Congestive Heart Failure, [[Congestive Heart Failure]])

• Epidemiology: may occur

Gastrointestinal Manifestations

• Digestive Complaints

Hematologic Manifestations

Polycythemia (see Polycythemia, [[Polycythemia]])

• Epidemiology
• Physiology
• Clinical
  • Polycythemia: hemoglobin >21 g/dL or hematocrit >63%

Neurologic Manifestations

• Depression (see Depression, [[Depression]])
• Fatigue (see Fatigue, [[Fatigue]])
• Headache (see Headache, [[Headache]])
• Sleep Disturbance
• Social Exclusion/Psychological Degradation

Pulmonary Manifestations

Dyspnea (see Dyspnea, [[Dyspnea]])

• Physiology

Pulmonary Hypertension (see Pulmonary Hypertension, [[Pulmonary Hypertension]])

• Epidemiology
• Physiology
  • Chronic Hypoxemia (see Hypoxemia, [[Hypoxemia]])
• Clinical
  • Dyspnea (see Dyspnea, [[Dyspnea]])
  • Hypoxemia (see Hypoxemia, [[Hypoxemia]])
  • Right-Sided Congestive Heart Failure (CHF) (see Congestive Heart Failure, [[Congestive Heart Failure]])

Chronic Hypoventilation (see Chronic Hypoventilation, [[Chronic Hypoventilation]])

• Epidemiology
• Physiology

Other Manifestations

• xxx

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Treatment

Acetazolamide (Diamox) (see Acetazolamide, [[Acetazolamide]])

• Rationale: carbonic anhydrase inhibitor induces a metabolic acidosis with a secondary increase in ventilation and decreased hypoxemia
• Clinical Efficacy
  • Trial of Acetazolamide in Chronic Mountain Sickness in Peru (Am J Respir Crit Care Med. 2005) [MEDLINE]
    • Acetazolamide Decreases Hypoventilation
      • Acetazolamide Increased Nocturnal SaO2 (by 5%), Decreased Nocturnal Heart Rate (by 11%), and Decreased Sleep Apnea-Hypopnea Episodes (by 74%)
    • Acetazolamide Decreased Erythropoietin and Decreased Hematocrit
  • Peruvian Trial of Chronic Acetazolamide in Chronic Mountain Sickness (Am J Respir Crit Care Med, 2008) [MEDLINE]
    • Chronic Acetazolamide (250 mg/day x 3 wks) Improved Erythrocytosis
    • Chronic Acetazolamide (250 mg/day x 3 wks) Improved Hypoxemia
    • Only Patients Treated for 6 mo Had a Decrease in Pulmonary Vascular Resistance (PVR)
    • Treatment Had No Adverse Effects

Phlebotomy (see Phlebotomy)

• Clinical Efficacy
  • Only Transiently Effective in Relieving Symptoms: however, phlebotomy undesirably decreases the oxygen content in distal tissues, worsening symptoms over time

Supplemental Oxygen (see Oxygen, [[Oxygen]])

• Clinical Efficacy
  • May Acutely Improve Symptoms: however, it is expensive, may not be available in high-altitude communities, and is not the best long-term treatment

Relocation to Sea Level

• Indications
  • High-Altitude Cerebral Edema (see High-Altitude Pulmonary Edema, [[High-Altitude Pulmonary Edema]]): usually associated with acute high altitude exposure (see High Altitude, [[High Altitude]])
  • High-Altitude Pulmonary Edema (see High-Altitude Pulmonary Edema, [[High-Altitude Pulmonary Edema]]): usually associated with acute high altitude exposure (see High Altitude, [[High Altitude]])
  • Refractory Chronic Mountain Sickness

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References

• Effect of acetazolamide on acute mountain sickness. N Engl J Med. 1968;279(16):839 [MEDLINE]
• Effects of acetazolamide and hypoxia on cerebrospinal fluid bicarbonate. J Appl Physiol. 1968;24(1):17 [MEDLINE]
• Relative effectiveness of acetazolamide versus medroxyprogesterone acetate in correction of chronic carbon dioxide retention. Am Rev Respir Dis. 1983;127(4):405 [MEDLINE]
• Effects of acute and chronic acetazolamide on resting ventilation and ventilatory responses in men. J Appl Physiol (1985). 1993;74(1):230 [MEDLINE]
• Acetazolamide in the treatment of acute mountain Sickness: clinical efficacy and effect on gas exchange. Ann Intern Med. 1992;116(6):461 [MEDLINE]
• Pathophysiology and epidemiology of chronic mountain sickness. Int J Sports Med. 1992 Oct;13 Suppl 1:S79-81 [MEDLINE]
• Acetazolamide: a treatment for chronic mountain sickness. Am J Respir Crit Care Med. 2005;172(11):1427 [MEDLINE]
• Andean, Tibetan, and Ethiopian patterns of adaptation to high-altitude hypoxia. Integr Comp Biol. 2006 Feb;46(1):18-24. doi: 10.1093/icb/icj004. Epub 2006 Jan 6 [MEDLINE]
• Acetazolamide for Monge’s disease: efficiency and tolerance of 6-month treatment. Am J Respir Crit Care Med. 2008 Jun 15;177(12):1370-6. doi: 10.1164/rccm.200802-196OC. Epub 2008 Apr 3 [MEDLINE]