The combination of alcohol plus cabin pressure at cruising altitude may threaten sleeping plane passengers' heart health, particularly on long haul flights, suggests the first study of its kind, published online in the respiratory journal Thorax . The duo lowers the amount of oxygen in the blood (SpO2) and raises the heart rate for a protracted period, even in the young and healthy, the findings indicate. The higher the alcohol consumption, the greater these effects might be, particularly among older passengers and those with pre-existing medical conditions, say the researchers, who suggest that it may now be time to consider restricting on-board access to alcohol on long haul flights.
Atmospheric pressure decreases exponentially with altitude, causing a drop in blood oxygen saturation level to around 90% (73 hPa) in healthy passengers at cruising altitude, explain the researchers. A further drop in SpO2 below this threshold is defined as hypobaric hypoxia-;or low blood oxygen level at higher altitude. Alcohol relaxes blood vessel walls, increasing the heart rate during sleep, an effect similar to that of hypobaric hypoxia, so the researchers wanted to find out if the combination of alcohol plus cabin pressure at cruising altitude might have an additive effect on sleeping passengers.
They therefore randomly allocated 48 people between the ages of 18 and 40 to two groups stratified by age, gender, and weight (BMI). Half were assigned to a sleep lab under normal ambient air pre.
