Discussion
hypoxia, ventricular ectopy, desaturation, supraventricular ectopy
HYPOXIC, HYPOXIA, VENTRICULAR ECTOPY
In our chamber study of hypoxic flight conditions among passengers over age 50, we observed a higher rate of ventricular ectopy and a higher presence and rate of supraventricular ectopy during simulated flight conditions. These associations increased over the duration of the flight. Previous studies, including within our study population, report associations between flight and heart rate or heart rate variabilityPrognoses for patients experiencing VE and SVE are, generally, mixed and there is uncertainty regarding the identification of patients who are at highest riskThe changes in VE and SVE presence and rate we observed were time-varying and increased relative to control conditions for the entire duration of the flight condition, showing the importance of studying the effects of prolonged flight durations. According to established medical guidelines, most of the participants in our study presenting with VE or SVE would have been considered low risk for hypoxia given their baseline oxygen saturationsOur participants were all over age 50, thus our results suggest that this group may show signs of cardiac stress at flight altitudes. Implications for younger passengers or crew are unclear based on our study, though we found that associations did not differ based on age being over 65, cardiac condition, or smoking status. Studies have also reported associations between flight, heart rate, and heart rate variability among young passengersBoth a strength and limitation of our study is our focus on oxygen levels as separate from other flight exposures. An Airliner Cabin Environment Research report demonstrated substantial oxygen desaturation among these participants during flight conditions, with approximately half of participants exhibiting moderate hypoxia (desaturation to 90% or below), and most participants experiencing mild to moderate hypoxia (desaturation to 95% or below)The Aerospace Medical Association recommends research into the effects of mild hypoxia for passengers and crew