Arterial blood gas analysis at 4559 m
| Subjects | PaO2 mmHg | PaCO2 mmHg | PA–aO2 mmHg | |
| No AMS | 14 | 39.6±4.5 | 30.0±3.6 | 7.9±3.7 |
| Mild AMS | 19 | 37.6±4.3 | 30.7±4.0 | 9.3±4.3 |
| Moderate–severe AMS | 10 | 33.9±4.0* | 31.1±2.8 | 12.5±4.5* |
| HAPE | 4 | 23.2±3.3*** | 28.4±3.5 | 26.0±2.9*** |
Analysis of arterial blood obtained from a femoral artery a few hours after arrival at the Margherita hut (Monte Rosa, Italy) in subjects with no acute mountain sickness (AMS), mild AMS (score 2–3 points according to Hackett et al. [103]), moderate-to-severe AMS (>3 points) or high-altitude pulmonary oedema (HAPE) (verified using chest radiography). PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension; PA–aO2: alveolar–arterial oxygen tension difference. *: p<0.05, compared with mild and no AMS; ***: p<0.001, compared with all groups. Data from [32].