TABLE 1.
Multiple regression analysis of factors related to P50
| Variables | In vivo P50 | Standard P50 | ||
|---|---|---|---|---|
| PCor (95% CI) | p | PCor (95% CI) | p | |
| SO2 | −0.581 (−0.659 to −0.490) | <0.001 | −0.563 (−0.645 to −0.469) | <0.001 |
| pH | −0.675 (−0.739 to −0.599) | <0.001 | 0.399 (0.285 to 0.502) | <0.001 |
| Lactate | 0.287 (0.166 to 0.400) | <0.001 | 0.289 (0.167 to 0.402) | <0.001 |
| Multiple regression r | 0.769 (0.711 to 0.816) | <0.001 | 0.679 (0.603 to 0.742) | <0.001 |
| The below analysis was performed excluding SO2 from independent variables; pH and PaCO2 were additionally excluded in standard P50 analysis | ||||
|---|---|---|---|---|
| PaO2/FiO2 | −0.314 (−0.428 to −0.190) | <0.001 | −0.146 (−0.278 to −0.009) | 0.038 |
| pH | −0.603 (−0.681 to −0.512) | <0.001 | — | — |
| Lactate | 0.324 (0.200 to 0.438) | <0.001 | 0.153 (0.016 to 0.284) | 0.030 |
| LDH | — | — | 0.361 (0.235 to 0.475) | <0.001 |
| OxyHb | −0.209 (−0.332 to −0.079) | 0.002 | −0.148 (−0.280 to −0.011) | 0.036 |
| Multiple regression r | 0.501 (0.395 to 0.594) | <0.001 | 0.508 (0.399 to 0.603) | <0.001 |
Abbreviations: LDH, lactate dehydrogenase; OxyHb, arterial oxyhaemoglobin; PaO2/FiO2, PaO2 to fraction of inspired oxygen; PCor, partial correlation coefficient.