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Nocturnal Continuous Positive Air Pressure therapy in patients with chronic mountain sickness. A randomized clinical trial

Rodrigo Soria


Universität Bern

Lay summary

Chronic Mountain Sickness (CMS) is a disease affecting people living at high altitude (usually above 3000 m a.s.l.). CMS is characterised by abnormal increase of red blood cells and lack of oxygen in the blood. Despite its impact on the health of people living at high altitude, the mechanisms behind this disease remain unclear. In the past years, in collaboration with the Instituto Boliviano de Biología de Altura (IBBA, the Bolivian Institute of High Altitude), we determined that CMS patients suffer from potentially serious sleep-disordered breathing in which breathing repeatedly decreases (hypopnea) or stops (apnea) and starts again. This correlated with poor function of blood vessels.

A machine (CPAP = Continuous Positive Air Pressure) that delivers air pressure through a piece fitting into the nose or placed over the nose and mouth while the patient is asleep can treat sleep apnea. We know that CPAP therapy does not only decrease sleep disorder symptoms but also improves the function of the heart and blood vessels.

Therefore, we speculate that nocturnal CPAP therapy in CMS patients could improve blood vessel function, and lower systemic and lung blood pressure, thus reducing cardiovascular risk.

The main objective of our research aims to show that CPAP therapy improves sleep disordered breathing and nocturnal lack of oxygen in CMS patients, and in turn, corrects the abnormal increase of red blood cells, decreases the patients’ symptoms and improves their cardiovascular function.


Regional focus High-altitude
Location La Paz - Bolivia
Funded amount 17,500 CHF
Project dates 7th October 2024 – 30th September 2025
Category Polar Access Fund
hypoxia, Chronic Mountain Sickness, Nocturnal Continuous Positive Air Pressure, Erythrocytosis, Sleep Disordered Breathing