Chronic Mountain Sickness

Epidemiology

General Comments

Chronic Mountain Sickness Occurs in High-Altitude Dwellers

Incidence

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

Physiology

Chronic High Altitude-Related Disease (see High Altitude)

Chronic Hypobaric Hypoxia
Increased Erythropoietin Production (see Serum Erythropoietin)

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)
- May Be Present
Hypercapnia (see Hypercapnia)
- May Be Present in Some Cases

Clinical Manifestations

Cardiovascular Manifestations

Right-Sided Congestive Heart Failure (CHF) (see Congestive Heart Failure)

Epidemiology
- May Occur

Gastrointestinal Manifestations

Digestive Complaints

Epidemiology
- XXXX

Hematologic Manifestations

Polycythemia (see Polycythemia)

Epidemiology
- XXXXXX
Physiology
- XXXXXX
Diagnosis
- Complete Blood Count (CBC) (see Complete Blood Count)
  - Polycythemia is Defined as a Hemoglobin >21 g/dL or Hematocrit >63%

Neurologic Manifestations

Depression (see Depression)

Epidemiology
- XXXX

Fatigue (see Fatigue)

Epidemiology
- XXXX

Headache (see Headache)

Epidemiology
- XXXX

Sleep Disturbance

Epidemiology
- XXXX

Social Exclusion/Psychological Degradation

Epidemiology
- XXXX

Pulmonary Manifestations

Dyspnea (see Dyspnea)

Physiology
- XXXXXX

Pulmonary Hypertension (see Pulmonary Hypertension)

Epidemiology
- XXXXXXX
Physiology
- Chronic Hypoxemia (see Hypoxemia)
Diagnosis
- Echocardiogram (see Echocardiogram)
  - Echocardiogram is the Standard Initial Test to Diagnose Pulmonary Hypertension
Findings
- Pulmonary Hypertension (see Pulmonary Hypertension)
Clinical
- Dyspnea (see Dyspnea)
- Hypoxemia (see Hypoxemia)
- Right-Sided Congestive Heart Failure (CHF) (see Congestive Heart Failure)

Respiratory Failure-Chronic Type I Hypoxemic (Hypoxemia) (see Hypoxemia and Respiratory Failure)

Diagnosis
- Arterial Blood Gas (ABG) (see Arterial Blood Gas)
  - Hypoxemia

Respiratory Failure-Chronic Type II-Hypoxemic, Hypercapnic (see Respiratory Failure)

Epidemiology
- XXXXX
Physiology
- Loss of Ventilatory Acclimatization to High Altitude-Associated Hypoxia, Leading to Central Hypoventilation (High Alt Med Biol, 2016) [MEDLINE]
Diagnosis
- Arterial Blood Gas (ABG) (see Arterial Blood Gas)
  - Hypoxemia
  - Hypercapnia

Treatment

Acetazolamide (Diamox) (see Acetazolamide)

Rationale
- Carbonic Anhydrase Inhibitor induces a Non-Anion Gap Metabolic Acidosis with a Secondary Increase in Ventilation, Resulting in 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)

Clinical Efficacy
- May Acutely Improve Symptoms
  - However, Supplemental Oxygen 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)
  - Usually Associated with Acute High Altitude Exposure (see High Altitude)
- High-Altitude Pulmonary Edema (see High-Altitude Pulmonary Edema)
  - Usually Associated with Acute High Altitude Exposure (see High Altitude)
- Refractory Chronic Mountain Sickness

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]
Chronic Mountain Sickness: Clinical Aspects, Etiology, Management, and Treatment. High Alt Med Biol. 2016 Jun 1; 17(2): 61–69 [MEDLINE]