Table 1.

Basic characteristics of subjects.

	PR	BC1	C2	BC2	C3	PO	P value
Subjects total, n	40	38	31	29	13	38
Females, n	19	17	14	13	5	17
Males, n	21	21	17	16	8	21
Age total (mean ± s.d.)	45.56 ± 12.06	46.08 ± 11.78	46.39 ± 12.36	47.18 ± 11.90	43.85 ± 13.74	45.37 ± 12.16	n.s.
Age females (mean ± s.d.)	40.94 ± 10.96	41.82 ± 10.62	42.00 ± 11.25	43.75 ± 10.23	37.20 ± 13.66	40.24 ± 10.86	n.s.
Age males (mean ± s.d.)	49.52 ± 11.78	49.52 ± 11.78	50.00 ± 12.37	49.75 ± 12.71	48.00 ± 12.87	49.52 ± 11.78	n.s.
SaO2 (mean ± s.d.)	97.57 ± 0.79	83.78 ± 4.59	72.71 ± 8.83	88.59 ± 2.34	68.8 ± 9.65	97.43 ± 0.69	<0.001
paO2 (mean ± s.d.)	95.35 ± 7.87	44.18 ± 4.52	34.34 ± 4.99	50.98 ± 3.57	30.38 ± 4.41	93.22 ± 7.22	<0.001
Hb (mean ± s.d.)	14.80 ± 0.93	15.35 ± 0.90	16.03 ± 1.10	17.03 ± 0.89	17.5 ± 1.00	15.21 ± 0.91	<0.001

Altitudes: PR, Pre expedition = 550 m; BC1, Base Camp 1 = 4.844 m; C2, Camp2 = 6022 m; BC2, Base Camp 2 (after acclimatization) = 4.844 m; C3, Camp3 = 7050 m; PO, Post expedition = 550 m.

SaO₂, saturation arterial oxygen (%); paO₂, partial pressure of oxygen (mmHg); Hb, haemoglobin (g/L).