Effect of acute hypoxia on QTc interval in respiratory patients undergoing fitness to fly tests

Current UK guidelines recommend administration of in-flight supplemental oxygen to patients with chronic respiratory disease who have sea level arterial oxygen saturations <92% or partial pressure of oxygen (Pao2) <6.6 kPa (50 mm Hg) during a hypoxic challenge fitness to fly test.1 Hypoxia has been shown to prolong cardiac repolarisation, assessed by the QT interval corrected for heart rate (QTc), and this may underlie the occurrence of potentially life-threatening cardiac arrhythmias2–4; however, few data exist about the cardiac response to hypoxia in patients with respiratory disease. To establish whether hypoxia prolongs the QTc, potentially increasing the risk of significant arrhythmias in patients with respiratory disease, we analysed data from respiratory patients referred to our lung function department for fitness to fly testing. Between …