Relative risk of failure at 4 hours compared with admission
| Initial pH | pH at 4 h | RR –8/min | RR –4/min | RR no change | RR +4/min | RR +8/min |
| 7.30 | 7.35 | 0.27 | 0.38 | 0.53 | 0.74 | 1.03 |
| 7.30 | 0.51 | 0.72 | 1.00 | 1.40 | 1.95 | |
| 7.25 | 1.05 | 1.46 | 2.04 | 2.85 | 3.97 | |
| 7.25 | 7.35 | 0.13 | 0.19 | 0.26 | 0.36 | 0.51 |
| 7.30 | 0.25 | 0.35 | 0.49 | 0.68 | 0.96 | |
| 7.25 | 0.51 | 0.72 | 1.00 | 1.40 | 1.95 |
RR = respiratory rate.