Nocturnal oxygen therapy reduces hypoxemia, apnea in COPD patients at altitude

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By Lisa Rappaport

(Reuters Health) - COPD patients who traveled to high altitudes from low-altitude homes experienced reduced hypoxemia and sleep apnea when they were treated with nocturnal oxygen therapy, a randomized, placebo-controlled crossover trial found.

The trial included 32 patients with COPD living below 800 meters with forced expiratory volume (FEV) between 30% and 80% and pulse oximetry of at least 92% who were not on oxygen therapy and had no history of sleep apnea.

Researchers evaluated patients at baseline when they were at 490 meters (1,608 feet) altitude, and then during two separate stays of two days and two nights at a hotel at 2,048 meters (6,719 feet) while participants received either nocturnal oxygen therapy or a placebo treatment. Between stays in the hotel, patients spent at least two weeks back below 800 meters.

Over the two nights in the hotel, patients received either nocturnal oxygen therapy or room air (placebo) administered at 3 L/min by nasal canula.

At 490 meters, mean nocturnal oxygen saturation (SpO2) as measured by pulse oximetry was 92% and mean apnea-hypopnea index (AHI) measured by polysomnography was 21.6 events per hour.

When patients went to 2,048 meters and received placebo treatment, mean SpO2 was 86% and mean AHI was 34.9/h. Nocturnal oxygen therapy increased SpO2 by a mean of 9 percentage points and decreased AHI by 19.7/h.

"These findings are novel and clinically important as they may alter clinical practice of counselling and treating patients with COPD travelling to high altitude," said senior study author Michael Furian of the Sleep Disorders Center and the Department of Respiratory Medicine at University Hospital Zurich in Switzerland.

"Nocturnal administration of supplemental oxygen may improve oxygenation, sleep-related breathing disturbances and prevent other adverse health effects," Furian said by email.

When patients were at high altitude in the study, they got a mean of 400 minutes of sleep with nocturnal oxygen therapy, compared to 349 minutes with placebo.

Compared to sleep at low altitude, placebo at high altitude was associated a decrease of rapid-eye movement sleep (mean 15.4% v 11.9%); sleep efficiency (mean 81% of time in bed v 72%); and arousal index (mean 13.7/h v 18.7/h).

With nocturnal oxygen therapy at high altitude, mean rapid-eye movement sleep was 15.1%; mean sleep efficiency was 78% of time in bed; and mean arousal index was 13.8/h.

Beyond its small size, another limitation of the study is that the participants all had moderate to severe COPD, and the results might not be generalizable to patients with mild or very severe COPD or to individuals who spent longer than two nights at high altitude, the study team notes in JAMA Network Open.

Even so, the results suggest that doctors should consider increased use of hypoxia simulation testing and the potential need to prescribe oxygen for high altitude travel to more COPD patients than they currently do, said Dr. Daniel Combs, co-author of an editorial accompanying the study and an assistant professor of pediatrics and medicine at the University of Arizona in Tucson.

"Additionally, given that flights operate with a cabin pressure higher than the altitude in this study, use of supplemental oxygen on transcontinental flights should be considered for more patients with COPD than currently are considered candidates for oxygen therapy," Dr. Combs said by email.

SOURCE: https://bit.ly/2ZaoriQ and https://bit.ly/31mruaC JAMA Network Open, online June 22, 2020.

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