Objective: To investigate the degree of oxygen saturation decline occurring in children during prolonged commercial air travel.
Methods: Oxygen saturation and heart rate were measured with a pulse oximeter in healthy pediatric passengers at sea level before boarding a commercial aircraft. These measurements were repeated after 3 hours and 7 hours of flight. Cabin pressure, true altitude, and cabin fraction of inspired oxygen (FiO2) were also recorded at 3 hours and 7 hours.
Results: Eighty healthy children (43 boys) aged 6 months to 14 years were studied during eight flights between Honolulu, Hawaii, and Taipei, Taiwan. Oxygen saturation declined, and heart rate increased after 3 hours (95.7%, 105 beats per minute [BPM]) and 7 hours (94.4%, 108 BPM) of flight compared to preflight levels at sea level (98.5%, 100 BPM) (P < 0.001). The 3-hour to 7-hour oxygen saturation and heart rate means differed significantly (P < 0.001, P = 0.014, respectively). The significant drop in oxygen saturation was associated with the decreased cabin partial pressure of oxygen (PO2)--PO2 was 159 mm Hg at sea level, 126 mm Hg after 3 hours, and 124 mm Hg after 7 hours--but the 3-hour and 7-hour difference suggests that flight duration may also contribute to worsened oxygen desaturation.
Conclusion: Oxygen saturation declines significantly during commercial airline travel with reduced aircraft cabin pressure and concomitant reduced cabin PO2. We did not observe an "acclimation" of oxygenation as the length of travel increased; rather, the oxygen saturation decline worsened, although it may be partially a result of the lower cabin PO2. Although there were no clinically noticeable ill effects at the level of oxygen saturation decline in these relatively healthy passengers, patients with preexisting anemia or cardiopulmonary disease are likely to experience greater degrees of clinical compromise with similar degrees of oxygen saturation decline.