Table 1.
Demographic characteristics
| Training cohort | pa | Validation cohort | pa | pb | |||
|---|---|---|---|---|---|---|---|
| NIV success N = 922 | NIV failure N = 529 | NIV success N = 400 | NIV failure N = 328 | ||||
| Age, years | 63 ± 16 | 64 ± 16 | 0.61 | 61 ± 17 | 61 ± 16 | 0.99 | < 0.01 |
| Male | 593 (64.3%) | 377 (71.3%) | < 0.01 | 273 (68.3%) | 217 (66.2%) | 0.58 | 0.85 |
| SOFA score | 4.6 ± 2.4 | 6.1 ± 3.0 | < 0.01 | 4.9 ± 2.1 | 6.0 ± 2.8 | < 0.01 | 0.03 |
| Septic shock | 67 (7.3%) | 138 (26.1%) | < 0.01 | 14 (3.5%) | 59 (18.0%) | < 0.01 | < 0.01 |
| Presence of COVID-19 | 4 (0.4%) | 0 (0%) | 0.30 | 17 (4.3%) | 26 (7.9%) | 0.04 | < 0.01 |
| ICU type | |||||||
| Medical | 450 (48.8%) | 300 (56.7%) | < 0.01 | 179 (44.8%) | 151 (46.0%) | 0.77 | 0.19 |
| Surgical | 145 (15.7%) | 58 (11.0%) | 0.01 | 58 (14.5%) | 50 (15.2%) | 0.83 | 0.60 |
| Mixed | 327 (35.5%) | 171 (32.3%) | 0.23 | 163 (40.8%) | 127 (38.7%) | 0.60 | 0.01 |
| Reason for NIV | |||||||
| Pneumonia | 363 (39.4%) | 347 (65.6%) | < 0.01 | 230 (57.5%) | 255 (77.7%) | < 0.01 | < 0.01 |
| Nonpulmonary sepsis | 113 (12.3%) | 79 (14.9%) | 0.15 | 29 (7.3%) | 27 (8.2%) | 0.68 | < 0.01 |
| Pancreatitis | 109 (11.8%) | 32 (6.0%) | < 0.01 | 23 (5.8%) | 8 (2.4%) | 0.04 | < 0.01 |
| CPE | 131 (14.2%) | 7 (1.3%) | < 0.01 | 40 (10.0%) | 4 (1.2%) | < 0.01 | < 0.01 |
| Cardiac problem other than CPE | 58 (6.3%) | 16 (3.0%) | < 0.01 | 11 (2.8%) | 10 (3.0%) | 0.83 | 0.02 |
| Pulmonary embolism | 16 (1.7%) | 10 (1.9%) | 0.84 | 8 (2.0%) | 3 (0.9%) | 0.36 | 0.73 |
| Trauma | 19 (2.1%) | 5 (0.9%) | 0.14 | 13 (3.3%) | 5 (1.5%) | 0.16 | 0.19 |
| Poison | 8 (0.9%) | 5 (0.9%) | > 0.99 | 3 (0.8%) | 0 (0%) | 0.26 | 0.29 |
| Postoperative respiratory failure | 9 (1.0%) | 3 (0.6%) | 0.55 | 9 (2.3%) | 3 (0.9%) | 0.24 | 0.13 |
| Asthma | 7 (0.8%) | 0 (0%) | 0.05 | 1 (0.3%) | 0 (0%) | > 0.99 | 0.28 |
| Inhalation injury | 4 (0.4%) | 0 (0%) | 0.30 | 1 (0.3%) | 1 (0.3%) | > 0.99 | > 0.99 |
| Other | 85 (9.2%) | 25 (4.7%) | < 0.01 | 32 (8.0%) | 12 (3.7%) | 0.02 | 0.22 |
| Presence of ARDS | |||||||
| Pulmonary ARDS | 49 (5.3%) | 102 (19.3%) | < 0.01 | 48 (12.0%) | 78 (23.8%) | < 0.01 | < 0.01 |
| Extrapulmonary ARDS | 109 (11.8%) | 51 (9.6%) | 0.22 | 9 (2.3%) | 8 (2.4%) | > 0.99 | < 0.01 |
| Underlying disease | |||||||
| Hypertension | 394 (42.7%) | 193 (36.5%) | 0.02 | 166 (41.5%) | 102 (31.3%) | < 0.01 | 0.10 |
| Diabetes mellitus | 261 (28.3%) | 130 (24.6%) | 0.13 | 91 (22.8%) | 68 (20.7%) | 0.53 | 0.01 |
| Chronic kidney disease | 109 (11.8%) | 41 (7.8%) | 0.02 | 73 (18.3%) | 41 (14.5%) | 0.04 | < 0.01 |
| Chronic liver disease | 24 (2.6%) | 22 (4.2%) | 0.12 | 21 (5.3%) | 23 (7.0%) | 0.35 | < 0.01 |
| Chronic heart disease | 300 (32.5%) | 109 (20.6%) | < 0.01 | 119 (29.8%) | 84 (25.6%) | 0.25 | 0.92 |
| Chronic lung disease | 143 (15.5%) | 69 (13.0%) | 0.22 | 60 (15.0%) | 40 (12.2%) | 0.28 | 0.60 |
| Presence of immunosuppression | 45 (4.9%) | 72 (13.6%) | < 0.01 | 60 (15.0%) | 81 (24.7%) | < 0.01 | < 0.01 |
| Variables collected before NIV | |||||||
| GCS | 14.8 ± 0.6 | 14.6 ± 1.0 | < 0.01 | 14.4 ± 1.5 | 14.2 ± 2.2 | 0.07 | < 0.01 |
| Heart rate, beats/min | 114 ± 24 | 118 ± 24 | < 0.01 | 106 ± 23 | 111 ± 23 | < 0.01 | < 0.01 |
| Respiratory rate, breaths/min | 30 ± 7 | 33 ± 8 | < 0.01 | 28 ± 6 | 30 ± 8 | < 0.01 | < 0.01 |
| Systolic blood pressure, mmHg | 134 ± 27 | 129 ± 26 | < 0.01 | 134 ± 24 | 128 ± 25 | < 0.01 | 0.49 |
| Diastolic blood pressure, mmHg | 78 ± 17 | 75 ± 17 | 0.02 | 78 ± 17 | 74 ± 15 | < 0.01 | 0.52 |
| pH | 7.42 ± 0.10 | 7.41 ± 0.12 | 0.11 | 7.43 ± 0.08 | 7.42 ± 0.10 | 0.04 | 0.11 |
| PaCO2, mmHg | 33 ± 8 | 32 ± 8 | 0.01 | 34 ± 7 | 34 ± 8 | 0.67 | < 0.01 |
| PaO2/FiO2, mmHg | 178 ± 74 | 153 ± 60 | < 0.01 | 147 ± 104 | 137 ± 85 | 0.16 | < 0.01 |
| HACOR score | 4.7 ± 2.7 | 6.4 ± 3.1 | < 0.01 | 5.7 ± 3.1 | 6.9 ± 3.5 | < 0.01 | < 0.01 |
| Variables collected after 1–2 h of NIV | |||||||
| GCS | 14.9 ± 0.4 | 14.5 ± 1.2 | < 0.01 | 14.5 ± 1.5 | 14.2 ± 2.2 | 0.03 | < 0.01 |
| Heart rate, beats/min | 105 ± 22 | 112 ± 24 | < 0.01 | 100 ± 21 | 107 ± 22 | < 0.01 | < 0.01 |
| Respiratory rate, breaths/min | 26 ± 6 | 31 ± 8 | < 0.01 | 25 ± 6 | 28 ± 8 | < 0.01 | < 0.01 |
| Systolic blood pressure, mmHg | 129 ± 23 | 127 ± 25 | 0.19 | 128 ± 22 | 124 ± 22 | 0.01 | 0.05 |
| Diastolic blood pressure, mmHg | 73 ± 14 | 71 ± 16 | 0.06 | 76 ± 15 | 73 ± 14 | 0.01 | < 0.01 |
| pH | 7.44 ± 0.07 | 7.40 ± 0.11 | < 0.01 | 7.44 ± 0.06 | 7.42 ± 0.09 | 0.01 | 0.22 |
| PaCO2, mmHg | 34 ± 7 | 34 ± 12 | 0.38 | 35 ± 7 | 35 ± 9 | 0.70 | 0.03 |
| PaO2/FiO2, mmHg | 241 ± 108 | 168 ± 89 | < 0.01 | 182 ± 67 | 140 ± 61 | < 0.01 | < 0.01 |
| HACOR score | 2.5 ± 2.2 | 6.0 ± 3.6 | < 0.01 | 3.9 ± 2.9 | 6.2 ± 3.5 | < 0.01 | < 0.01 |
| De novo acute respiratory failure | 508 (55.1%) | 358 (69.6%) | < 0.01 | 233 (58.3%) | 215 (65.5%) | < 0.05 | 0.93 |
| Outcome | |||||||
| Death in hospital | 53 (5.7%) | 256 (48.4%) | < 0.01 | 15 (3.8%) | 153 (46.6%) | < 0.01 | 0.35 |
| Length of ICU stay, days | 6 (4–10) | 7 (3–13) | 0.14 | 7 (5–12) | 9 (4–16) | 0.20 | < 0.01 |
| Length of hospital stay, days | 16 (10–26) | 11 (5–22) | < 0.01 | 18 (11–28) | 14 (6–24) | < 0.01 | 0.02 |
NIV noninvasive ventilation, SOFA sequential organ failure assessment, ICU intensive care unit, CPE cardiogenic pulmonary edema, ARDS acute respiratory distress syndrome, GCS Glasgow Coma Scale, HACOR heart rate, acidosis, consciousness, oxygenation, and respiratory rate
ap for the difference between NIV success versus failure
bp for the difference between training cohort versus validation cohort