Children at high altitude have less nocturnal periodic breathing than adults

Although children commonly travel to high altitudes, their respiratory adaptation to hypoxia remains elusive. Therefore, in the present study respiratory inductive plethysmography, pulse oximetry (S(p,O(2))) and end-tidal CO(2) tension (P(ET,CO(2))) were recorded in 20 pre-pubertal children (aged 9-12 yrs) and their fathers during 1 night in Zurich (490 m) and 2 nights at the Swiss Jungfrau-Joch research station (3,450 m) following ascent by train within >3 h. In children, mean±sd nocturnal Sp,O2 fell from 98±1% at 490 m to 85±4 and 86±4% at 3,450 m (nights 1 and 2, respectively); PET,CO2decreased significantly from 37±6 to 32±3 and 33±4 mmHg (3,450 versus 490 m). In adults, changes in nocturnal Sp,O2 and PET,CO2at 3,450 m were similar to those in children. Children spent less time in periodic breathing at 3,450 m during night 1 and 2 (8±11 and 9±13%, respectively) than adults (34±24 and 22±17%, respectively), and their apnoea threshold for CO2 was lower compared with adults (27±2 and 30±2 mmHg, respectively, both nights). Sp,O2, PET,CO2 and time in periodic breathing at altitude were not correlated between children and their fathers. In conclusion, children revealed a similarly reduced nocturnal O2 saturation and associated hyperventilation at high altitude as adults but their breathing pattern was more stable, possibly related to a lower apnoea threshold for CO2.