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More severe sleep disordered breathing, nocturnal hypoxemia observed in patients with chronic mountain sickness

Patients with chronic mountain sickness had worse sleep disordered breathing and severe nocturnal hypoxemia compared with a control group, with a subgroup of patients who had a patent foramen ovale showing even more severe sleep disordered breathing and hypoxemia, according to recent research published in Chest.

“Most importantly, alterations in nocturnal breathing and oxygenation were associated with systemic and pulmonary vascular dysfunction. In the presence of a [patent foramen ovale (PFO)], sleep disordered breathing and cardiovascular alterations were even more pronounced,” Emrush Rexhaj, MD, from the department of cardiology and clinical research at Inselspital, University of Bern, Switzerland, and colleagues wrote. “This could suggest that in analogy to recent observations in patients with sleep apnea syndrome at low altitude, PFO closure may improve systemic and pulmonary vascular function and sleep disordered breathing in patients with [chronic mountain sickness (CMS)].”

Rexhaj and colleagues measured the sleeping patterns of 23 patients with CMS (mean age, 52.8 years; SD = 9.8 years) and 12 patients without CMS in a control group (mean age, 47.8 years; SD = 7.8 years). The patients recruited were either born or were currently living at a high altitude of 3,600 meters to 4,000 meters; the results were obtained at 3,600 meters. CMS was scored according to the rate of breathlessness and/or palpitations, cyanosis, sleep disturbances, paresthesia, headache, tinnitus and vein dilation.

Over the course of two nights, Rexhaj and colleagues provided either respiratory dead space or no dead space for patients with SDB and one night of no dead space to control patients. The researchers further investigated a subgroup of 15 patients with PFO, according to the abstract.

They found that the apnea/hypopnea index (AHI) of patients with SDB was more severe than patients in the control group (38.9 nb/h ± 25.5 nb/h vs. 14.3 nb/h ± 7.8 nb/h) and nocturnal hypoxemia (SaO₂) was also more severe in SDB patients (80.2% ± 3.6% vs. 86.8% ± 1.7%). Researchers also found a further association between systemic blood pressure (P = .001) and pulmonary-artery pressure (P = .024) with AHI. In the subgroup of patients with PFO, Rexhaj and colleagues noted more severe SDB (48.8 nb/h ± 24.7 nb/h vs. 14.8 nb/h ± 7.3 nb/h) and hypoxemia was associated with these patients compared with the standard SDB and control groups, according to the abstract. – by Jeff Craven

Disclosure: One researcher reports serving on the advisory board for Nightbalance.