Pulmonary Artery Pressure Response to Simulated Air Travel in a Hypobaric Chamber.

Abstract

Hypoxia-induced elevation in pulmonary artery pressure during air travel may contribute to the worldwide burden of in-flight medical emergencies. The pulmonary artery pressure response may be greater in older passengers, who are more likely to require flight diversion due to a medical event. Understanding these effects may ultimately improve the safety of air travel. We studied 16 healthy volunteers, consisting of a younger group (aged <25 yr) and an older group (aged >60 yr). Using a hypobaric chamber, subjects undertook a 2-h simulated flight at the maximum cabin pressure altitude for commercial airline flights (8000 ft; 2438 m). Higher and lower altitudes within the aeromedical range were also explored. Systolic pulmonary artery pressure (sPAP) was assessed by Doppler echocardiography. There was a progressive increase in sPAP which appeared to be biphasic, with a small initial increase and a larger subsequent rise. Overall, sPAP increased by 5±1 mmHg from baseline to 35±1 mmHg at 8000 ft, an increase of 18%. The sPAP response to 8000 ft was greater in the older group than the younger group. This study confirms that pulmonary artery pressure increases during simulated air travel, and provides preliminary evidence that this response is greater in older people. Advancing age may increase in-flight susceptibility to adverse pulmonary vascular responses in passengers, aircrew, and aeromedical patients.