Combination therapy reduces sleep apnea symptoms at altitude

By Lucy Piper, Senior medwireNews Reporter

Patients with obstructive sleep apnea (OSA) can better control their symptoms when traveling to higher altitudes by combining autoadjusted continuous positive airway pressure (autoCPAP) with acetazolamide, research suggests.

"Our study provides important information for patients with OSA planning a stay at altitude because they can continue using their CPAP in autoadjusting mode during altitude travel and enhance this treatment with acetazolamide if they want to spend less time awake at night, to achieve a higher arterial oxygen saturation and an optimal control of sleep apnea," say Konrad Bloch, from University Hospital of Zurich in Switzerland, and colleagues.

They randomly assigned 51 patients with OSA living below an altitude of 800 m and receiving CPAP therapy to receive either autoCPAP therapy plus placebo (autoCPAP alone) or autoCPAP therapy plus acetazolamide 750 mg during two 3-day trips to mountain villages at 1630 m and 2590 m. The two trips were separated by a 2-week washout period at 800 m, after which participants received the alternative treatment combination.

The results, published in JAMA, showed that nocturnal oxygen saturation was 1% higher with autoCPAP plus acetazolamide than with autoCPAP alone at 1630 m and 2% higher at 2590 m. Also, at 2590 m, patients receiving acetazolamide in addition to autoCPAP spent a median 13% of the night with oxygen saturation below 90% compared with a median of 57% for those receiving autoCPAP alone.

The combination of autoCPAP and acetazolamide was also superior for controlling sleep apnea, with significant median reductions on the apnea/hypopnea index (AHI) of 3.2 events/hour at 1630 m and 9.2 events/hour at 2590 m, compared with autoCPAP alone.

The researchers note that this reduction was mainly due to a decrease in the number of central apneas/hypopneas, particularly during nonrapid eye movement sleep.

They estimate that "to prevent one patient from experiencing an increase of the AHI to greater than 10/h or a decrease of the oxygen saturation to less than 90% at 2590 m, two patients or three patients, respectively, had to be treated with acetazolamide."

The team concludes: "Alleviating hypoxemia at rest and during exercise at altitude by acetazolamide may potentially contribute to reducing the risk of adverse effects of altitude exposure, in particular in patients with OSA and cardiovascular comorbidities."

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