Abstract
Air travel guidelines recommend using baseline arterial oxygen levels and the hypoxic challenge test (HCT) to predict in-flight hypoxaemia and the requirement for in-flight oxygen in patients with lung disease. The purpose of the present study was to (i) quantify the hypoxaemic response to air travel and (ii) identify baseline correlate(s) to predict this response in passengers with non-obstructed lung disease.
Fourteen passengers (seven women) with chronic non-obstructed lung disease volunteered for this study. The study involved three phases: (i) respiratory function testing; (ii) in-flight measures (SpO(2), cabin pressure and dyspnoea); and (iii) a HCT. The in-flight hypoxaemic response was compared with the baseline arterial oxygen level, respiratory function and the HCT.
All subjects flew without oxygen and no adverse events were recorded in-flight. Mean cabin pressure was 593 +/- 16 mm Hg. Pre-flight SpO(2) was 95 +/- 3% and significantly decreased to 85 +/- 9% in-flight, with further significant falls in subjects who walked during the flight (nadir SpO(2) 78 +/- 11%). The pre-flight SpO(2) showed the strongest correlation with in-flight SpO(2) (r = 0.91, P < 0.001). The HCT SpO(2) was moderately correlated to the in-flight SpO(2) (r = 0.58, P < 0.05). Spirometry, D(L,CO) and TLC measurements did not correlate with in-flight SpO(2).
Significant in-flight desaturation can be expected in passengers with non-obstructive lung disease. Respiratory function did not predict in-flight desaturation. We found a good relationship between pre-flight SpO(2) and in-flight SpO(2) which supports the role of pre-flight oximetry for predicting in-flight hypoxaemia in passengers with non-obstructed lung disease.