Comparison of patient’s characteristics by time to NIV across the two audits period 2008 and 2014
| Variable | <60 min | 60–179 min | 180–1400 min | 24 hours | P value | <60 min | 60–179 min | 180–1400 min | >24 hours | P value |
| n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | |||
| 249 (24.1) | 267 (25.9) | 323 (31.3) | 193 (18.7) | 249 (20.9) | 256 (21.5) | 465 (39.0) | 221 (18.6) | |||
| First ABGs | <0.001 | 0.734 | ||||||||
| No | 0 (0) | 0 (0) | 3 (0.9) | 9 (4.8) | 1 (0.4) | 3 (1.2) | 5 (1.1) | 3 (1.4) | ||
| Yes | 249 (100) | 265 (100) | 320 (99.1) | 180 (95.2) | 248 (99.6) | 253 (98.8) | 460 (98.9) | 218 (98.6) | ||
| First ABGs result, mean (SD) | ||||||||||
| pH | 7.2 (0.1) | 7.3 (0.1) | 7.3 (0.1) | 7.4 (0.1) | <0.001 | 7.2 (0.1) | 7.3 (0.1) | 7.3 (0.1) | 7.4 (0.1) | <0.001 |
| PCO2 | 11 (3.3) | 10 (2.7) | 9.1 (2.7) | 7.3 (2) | <0.001 | 10.8 (3.4) | 10.4 (3) | 9 (2.4) | 7.8 (2.6) | <0.001 |
| PO2 | 12.3 (8.7) | 11.7 (7.9) | 10.4 (6.2) | 9.7 (5) | <0.001 | 9.8 (5.5) | 9.3 (5) | 9 (4.8) | 9 (4) | <0.001 |
| HCO2 | 29.9 (7.3) | 30.4 (7) | 30.4 (7) | 29.7 (5.9) | 0.676 | 29.9 (7) | 30.4 (7.3) | 30.1 (6.1) | 29.7 (6.8) | 0.168 |
| Second ABGs | <0.001 | 0.399 | ||||||||
| No | 11 (5) | 5 (2) | 24 (8.2) | 28 (19.7) | 9 (3.6) | 6 (2.3) | 20 (4.3) | 5 (2.3) | ||
| Yes | 211 (95) | 245 (98) | 270 (91.8) | 114 (80.3) | 240 (96.4) | 250 (97.7) | 445 (95.7) | 216 (97.7) | ||
| Second ABGs result, mean (SD) | ||||||||||
| pH | 7.3 (0.1) | 7.3 (0.1) | 7.3 (0.1) | 7.3 (0.1) | <0.001 | 7.3 (0.1) | 7.3 (0.1) | 7.3 (0.1) | 7.3 (0.1) | <0.001 |
| PCO2 | 9.7 (2.9) | 9.4 (2.4) | 9.1 (2.5) | 8.9 (2.4) | 0.038 | 9.4 (3) | 9.6 (2.7) | 9 (2.4) | 8.7 (2.3) | <0.001 |
| PO2 | 10 (5.4) | 9.7 (5.1) | 9.1 (3.8) | 8.4 (2.7) | 0.012 | 9.1 (4.8) | 8.9 (4.5) | 8.4 (2.9) | 8.7 (3.8) | 0.19 |
| HCO3 | 29.5 (7.2) | 30.3 (7.2) | 30.2 (7.4) | 30.6 (6.7) | 0.57 | 29.6 (6.6) | 30 (6.4) | 29.6 (6.3) | 29.9 (7.4) | 0.796 |
| Other significant condition | 0.917 | 0.854 | ||||||||
| No | 57 (23.6) | 63 (24.1) | 72 (22.6) | 41 (21.5) | 38 (15.3) | 42 (16.4) | 82 (17.6) | 35 (15.8) | ||
| Yes | 185 (76.4) | 198 (75.9) | 246 (77.4) | 150 (78.5) | 211 (84.7) | 214 (83.6) | 383 (82.4) | 186 (84.2) | ||
| Inpatient death | <0.001 | <0.001 | ||||||||
| No | 203 (81.5) | 218 (81.6) | 244 (75.5) | 110 (57) | 220 (88.4) | 223 (87.1) | 395 (84.9) | 147 (66.5) | ||
| Yes | 46 (18.5) | 49 (18.4) | 79 (24.5) | 83 (43) | 29 (11.6) | 33 (12.9) | 70 (15.1) | 74 (33.5) | ||
ABGs, arterial blood gases; NIV, non-invasive ventilation.