3 Univariate comparison between patients that succeeded or failed after treatment with noninvasive positive pressure ventilation
| Success | Failure | p-value | |
| Subjects n | 797 | 236 | |
| Age | 69.1±9.1 | 71.0±8.5 | 0.0041 |
| Glasgow Coma Scale | 13.7±1.9 | 11.6±3.0 | <0.0001 |
| APACHE II score | 18.9±5.1 | 25.2±6.7 | <0.0001 |
| ABG at admission | |||
| Pa,O2 mmHg | 54.7±16.3 | 53.9±19.0 | 0.5331 |
| Pa,CO2 mmHg | 78.8±16.2 | 86.0±19.0 | <0.0001 |
| pH | 7.29±0.06 | 7.25±0.08 | <0.0001 |
| RR | 28.7±5.8 | 32.0±7.3 | <0.0001 |
| Pa,O2/Fi,O2 | 189.7±47.2 | 155.1±57.8 | <0.0001 |
| ABG after 2 h | |||
| Pa,O2 mmHg | 63.4±11.9 | 62.8±21.5 | 0.5972 |
| Pa,CO2 mmHg | 69.0±14.1 | 76.8±18.7 | <0.0001 |
| pH | 7.34±0.05 | 7.27±0.1 | <0.0001 |
Data are presented as mean±sd. APACHE: acute physiology and chronic health evaluation; ABG: arterial blood gases; Pa,O2: arterial oxygen tension; Pa,CO2: carbon dioxide arterial tension; RR: respiratory rate; Fi,O2: inspiratory oxygen fraction.