Table. Characteristics of Neonates in the 3 Subgroups of Interest.
| Characteristic | Neonates, No. (%) (N = 1337) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤28 wk Gestation (n = 455) | Ventilated ≥1 wk from birth (n = 375) | CO2 >50 mm Hg before or in the 24 h after extubation (n = 307) | ||||||||||
| NCPAP (n = 134) | NIPPV (n = 160) | NHFOV (n = 161) | P value | NCPAP (n = 110) | NIPPV (n = 131) | NHFOV (n = 134) | P value | NCPAP (n = 123) | NIPPV (n = 94) | NHFOV (n = 90) | P value | |
| Gestational age, mean (SD), wk | 27.3 (0.9) | 27.3 (0.9) | 27.2 (0.9) | .76 | 28.7 (1.8) | 28.9 (1.9) | 28.8 (1.8) | .82 | 29.1 (1.9) | 29 (1.9) | 28.6 (1.8) | .20 |
| Birth weight, mean (SD), g | 1085 (202) | 1040 (194) | 1033 (186) | .05 | 1205 (325) | 1271 (393) | 1183 (291) | .09 | 1234 (293) | 1309 (395) | 1252 (323) | .04 |
| Sex | ||||||||||||
| Male | 81 (60.4) | 100 (62.5) | 98 (60.8) | .93 | 58 (52.7) | 79 (60.3) | 81 (60.4) | .39 | 69 (56.1) | 59 (62.7) | 55 (61.1) | .57 |
| Female | 53 (39.6) | 60 (37.5) | 63 (39.1) | 52 (47.3) | 52 (39.7) | 53 (39.6) | 54 (43.9) | 35 (37.2) | 35 (38.9) | |||
| Small for gestational age | 9 (6.7) | 13 (8.1) | 15 (9.3) | .72 | 10 (9.1) | 8 (6.1) | 14 (10.4) | .43 | 11 (8.9) | 6 (6.4) | 10 (11.1) | .52 |
| Twins | 38 (28.3) | 48 (30) | 51 (31.7) | .82 | 34 (30.9) | 35 (26.7) | 45 (33.6) | .47 | 30 (24.4) | 19 (20.2) | 21 (23.3) | .76 |
| Cesarean delivery | 49 (36.5) | 58 (36.2) | 56 (34.7) | .94 | 57 (51.8) | 72 (54.9) | 80 (59.7) | .45 | 68 (55.3) | 45 (47.9) | 52 (57.8) | .36 |
| Prenatal steroidsa | 63 (47.0) | 74 (46.2) | 81 (50.3) | .74 | 46 (41.8) | 54 (41.2) | 49 (36.5) | .64 | 58 (47.1) | 41 (45) | 39 (43.3) | .82 |
| Clinical Risk Index for Babies-II score, mean (SD) | 7.8 (3.1) | 7.8 (3.2) | 8.2 (2.8) | .31 | 6.7 (3.3) | 6.2 (3.7) | 6.5 (3.1) | .47 | 5.9 (3.2) | 5.9 (3.6) | 6.1 (3.4) | .88 |
| 5-Factor Apgar score, median (IQR) | 8 (7-9) | 8 (7-9) | 9 (8-9) | .31 | 9 (8-9) | 8 (7-9) | 9 (8-9) | .34 | 9 (8-9) | 8 (7-10) | 9 (8-9) | .20 |
| Surfactant replacementb | 121 (90.3) | 151 (94.4) | 145 (90.1) | .30 | 99 (90) | 121 (92.4) | 121 (90.3) | .77 | 109 (88.6) | 87 (92.5) | 82 (91.1) | .60 |
| Early-onset sepsis | 3 (2.2) | 7 (4.4) | 3 (1.9) | .35 | 5 (4.5) | 5 (3.8) | 2 (1.5) | .35 | 6 (4.9) | 6 (6.4) | 4 (4.4) | .82 |
| Postnatal age at extubation, median (IQR), d | 4 (2-8) | 4 (2-8) | 5 (2-8) | .13 | 10 (8-15) | 10 (8-13) | 9 (7-12) | .51 | 5 (3-9) | 6 (3-9) | 5 (3-8) | .23 |
| Oxygenation index at extubation, mean (SD)c,d | 3.7 (1.8) | 3.7 (2.5) | 4.0 (2.8) | .53 | 4.2 (2.4) | 4.1 (2.5) | 4.1 (2.7) | .96 | 3.7 (2.2) | 4.5 (3.0) | 4.7 (3.8) | .04 |
| pH at extubation, mean (SD)d | 7.35 (0.11) | 7.35 (0.09) | 7.34 (0.09) | .24 | 7.36 (0.11) | 7.36 (0.09) | 7.35 (0.09) | .92 | 7.32 (0.10) | 7.33 (0.10) | 7.29 (0.10) | .07 |
| Partial pressure of carbon dioxide at extubation, mean (SD), mm Hgd | 40.2 (11.3) | 39.2 (10.4) | 41.3 (11.3) | .63 | 41.9 (11.5) | 41.3 (11.9) | 41.7 (12.2) | .34 | 46.1 (12.5) | 47.5 (13.6) | 50.4 (13.1) | .06 |
| Airway pressure at extubation, mean (SD), cm H2O | 6.7 (0.8) | 7.5 (2.1) | 7.9 (2.2) | <.001 | 6.4 (1.6) | 8.1 (2.4) | 8 (2.0) | <.001 | 6.6 (2.2) | 7.8 (2.2) | 8.1 (2) | <.001 |
| Bronchopulmonary dysplasia | 99 (73.8) | 104 (65) | 97 (60.2) | .04 | 62 (56.4) | 70 (53.4) | 61 (45.5) | .20 | 60 (48.8) | 43 (45.7) | 42 (46.7) | .90 |
Abbreviations: NCPAP, nasal continuous positive airway pressure; NHFOV, noninvasive high-frequency oscillation ventilation; NIPPV, noninvasive positive pressure ventilation.
Prenatal steroid is considered to have occurred if dosing was complete (ie, 2 12-mg doses of betamethasone, 24 hours apart from each other).
Surfactant replacement was always performed by the intubation-surfactant-extubation technique.
Oxygenation index is calculated as follows: (inspired oxygen faction × mean airway pressure × 100) / partial oxygen pressure.
Oxygenation index, pH, partial pressure of carbon dioxide, and airway pressure values are those measured at 24 hours from the first extubation, that is from the onset of the trial intervention (ie, the time point for gas analysis and data capture).