Table 1—

Nocturnal polygraphic recordings

	Children			Adults
	Baseline 490 m	3450 m		Baseline 490 m	3450 m
	Baseline 490 m	Day 1	Day 2	Baseline 490 m	Day 1	Day 2
Subjects n	20	19	17	20	19	19
Time in bed min	519±52	484±44^§	506±29^¶	515±56	462±23^§	495±37^¶
Ventilation L·min⁻¹	3.2±0.6⁺	4.4±0.7^+,§	4.1±0.8^+,§	6.3±1.4	8.1±1.1^§	7.4±1.1^¶,§
% of baseline	100	142±38^§	128±38^§	100	135±27^§	123±27^§
V_T L	0.20±0.05⁺	0.23±0.05⁺	0.22±0.05⁺	0.41±0.09	0.48±0.07^§	0.45±0.09^¶,§
% of baseline	100	120±38	110±42	100	122±21^§	111±19^¶,§
Breath rate L·min⁻¹	16.2±2.1	19.6±3.0^§	19.3±2.8^§	15.4±2.1	17.2±2.2^§	17.0±2.3^§
% of baseline	100	121±20^+,§	121±16^+,§	100	112±12^§	111±7^§
V_T/t_I L·s⁻¹	0.13±0.03⁺	0.17±0.03^+,§	0.16±0.03^+,§	0.22±0.06	0.31±0.05^§	0.27±0.04^¶,§
% of baseline	100	137±40^§	122±37^§	100	145±32^§	125±29^¶,§
S_p,O₂%	98±1	85±4^§	86±4^§	96±1	84±3^§	85±4^§
P_ET,CO₂mmHg	37±6	32±3^§	33±4^§	37±6	32±2^§	31±2^§
f_C min⁻¹	68±6⁺	88±10^+,§	86±9^¶,+,§	56±10	67±9^§	63±7^¶,§
% of baseline	100	131%±12^§	126±9^+,§	100	120±15^§	112±11^¶,§
Rest time min	478±56	426±62^§	456±36^¶	483±61	406±45^§	439±48^§
Estimated sleep efficiency^# %	92±4	88±7^§	90±5	94±4	88±8^§	89±5^§

Data are presented as mean±sd, unless otherwise stated. V_T: tidal volume; t_I: inspiratory time; S_p,O₂: O₂ saturation measured by pulse oximetry; P_ET,CO₂: end-tidal CO₂ tension; f_C: cardiac frequency. ^#: rest time measured by actigraphy in per cent of time in bed; ^¶: p<0.05 versus day 1; ⁺: p<0.05 versus adults; ^§: p<0.05 versus 460 m.