Sleep Apnea Raises Risk Of Low Blood Oxygen During Air Travel

People who have obstructive sleep apnea are more likely to have low blood oxygen and experience higher physiological stress (which can raise heart risk) during air travel than people who do not suffer from the condition, suggesting they may need extra oxygen during flight, like patients with chronic lung diseases.

The study was the work of Leigh Seccombe, MSc, of Concord Repatriation General Hospital in Sydney, Australia, and colleagues, and was presented on Sunday 18th May 2008 at the annual meeting of the American Thoracic Society in Toronto, Canada.

Obstructive sleep apnea (OSA) is a common condition where a person's breathing pauses during sleep because of an obstruction in their airway.

In this study, Seccombe and colleagues investigated the physiological response of 22 patients with severe OSA and without lung disease, to a simulation of an aircraft cabin and compared it to that of 10 healthy subjects.

The researchers measured the participants' ventilatory response (the volume of air going in and out of the lungs), and also the amount of oxygen circulating in their bloodstream.

In the simulator, the participants were exposed to the equivalent of cabin air at 6,000 ft (16.8 per cent O2) and 8,000 ft (15.1 per cent O₂).

The results showed that:

* Half of the 22 OSA patients would need supplemental oxygen when flying, if current guidelines issued to patients with lung disease were to be followed.

* There was no difference in the ventilatory response change with increasing simulated cabin altitudes between the OSA and the healthy group.

* But in the OSA group only, the oxygen uptake and heart rates were significantly higher than they would be at "sea level".

* Oxygen demand in the OSA group went up from 0.3 liters per minute at sea level to just under 0.4 l/m at 8,000 feet.

The researchers concluded that:

"Patients with OSA, without lung disease, are more likely to develop significant hypoxemia [low blood oxygen] and have increased oxygen demands during flight. Ventilatory response was not impaired."

Speculating on their findings, Seccombe told MedPage Today that it was too early to say what the clinical implications might be:

"Many people fly, many people get hypoxic, but not many have adverse events," said Seccombe, adding that one explanation could be obesity, since the average BMI (body mass index) of the OSA participants was 36 compared to 24 for the healthy participants.

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