Chronic Mountain Sickness: Clinical Aspects, Etiology, Management, and Treatment

Abstract

Villafuerte, Francisco C., and Noemí Corante. Chronic mountain sickness: clinical aspects, etiology, management, and treatment. High Alt Med Biol. 17:61-69, 2016.-Millions of people worldwide live at a high altitude, and a significant number are at risk of developing Chronic Mountain Sickness (CMS), a progressive incapacitating syndrome caused by lifelong exposure to hypoxia. CMS is characterized by severe symptomatic excessive erythrocytosis (EE; Hb ≥19 g/dL for women and Hb ≥21 g/dL for men) and accentuated hypoxemia, which are frequently associated with pulmonary hypertension. In advanced cases, the condition may evolve to cor pulmonale and congestive heart failure. Current knowledge indicates a genetic predisposition to develop CMS. However, there are important risk factors and comorbidities that may trigger and aggravate the condition. Thus, appropriate medical information on CMS is necessary to provide adequate diagnosis and healthcare to high-altitude inhabitants. After reviewing basic clinical aspects of CMS, including its definition, diagnosis, and common clinical findings, we discuss aspects of its etiology, and address its epidemiology, risk factors, and treatment.

Keywords: chronic hypoxia; chronic mountain sickness; excessive erythrocytosis; high altitude.

FIG. 1.

Typical CMS patient. Note the deep purplish color of lips and gums as a consequence of EE and low SpO₂. Vein dilatation is particularly evident in the lower limbs, and characteristic clubbing of fingers and marked cyanosis are evident in nail beds and palms of the hands. CMS, chronic mountain sickness; EE, excessive erythrocytosis.

FIG. 2.

Relationship between hematocrit and pulmonary ventilation in native Andean healthy highlanders (●) and CMS patients (○) at 4500 m. The figure shows the inverse relationship between these two variables using individual data points. Reproduced from Winslow and Monge (1987).