Objectives: To assess the effect of altitude and acclimatisation on cardiorespiratory function and well-being in healthy children.
Methods: A daily symptom diary, serial measurements of spirometry, end-tidal carbon dioxide (etCO2) and daytime and overnight pulse oximetry (SpO2), were undertaken at sea level and altitudes up to 3500 m in healthy children during a trekking holiday. SpO2 at altitude was compared with that in flight and during acute hypoxic challenge (breathing 15% oxygen) at sea level.
Results: Measurements were obtained in nine children aged 6–13 years (median 8). SpO2 decreased significantly during the hypoxic challenge (difference −5%, 95% CI −6 to −3%, p<0.01) but remained above 90% in all children. There was a significant fall in daytime and overnight SpO2 (95% CI −11.9 to −7.5% and −12 to −8, respectively) and etCO2 (−8.5 to −4.5 mm Hg) as the children ascended to 3500 m. There was a significant increase in SpO2 (95% CI 1.1 to 4.9%) and a further drop in etCO2 (−5.9 to −0.8 mm Hg) after a week at altitude, etCO2 being negatively correlated with SpO2. There was no correlation between SpO2 during hypoxic challenge, in flight or at altitude. Lung function remained within 7% of baseline in all but two children, in whom reductions of up to 23% in FVC and 16% FEV1 were observed at altitude. The children generally remained well, but the Lake Louise scoring system was unreliable in this age group.
Conclusions: A wide range of physiological responses to altitude are evident in healthy children. This study should inform future larger studies in children to improve understanding of responses to hypoxia in health and disease.
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Competing interests: None.
Funding: The Young Everest Study received funding from Smiths Medical. Research at the Institute of Child Health and Great Ormond Street Hospital for Children NHS Trust benefits from R&D funding received from the NHS Executive.
Ethics approval: The study was approved by UCL Research Ethics Committee.
Patient consent: Obtained.