Comparison of exhalation through nCPAP for the two interfaces
| Exhaled mask n=20 | Not exhale mask n=30 | P value | Exhaled prongs n=23 | Not exhale prongs n=27 | P value | |
| GA birth, days (median (IQR)) | 33+2 (31+2 to 37+6) | 33+1 (31+3 to 39+3) | 0.937 | 35+3 (31+4 to 39+3) | 32+6 (30+0 to 35+4) | 0.087 |
| PMA, days (median (IQR)) | 33+4 (31+5 to 38+1) | 33+4 (32+2 to 39+4) | 0.566 | 35+3 (31+5 to 39+4) | 33+3 (32+1 to 35+6) | 0.316 |
| Postnatal age, days (median (IQR)) | 1 (0 to 4) | 1 (1 to 4) | 0.451 | 1 (0 to 1) | 3 (1 to 4) | 0.015 |
| Weight, g (median (IQR)) | 1864 (1469 to 3386) | 2017 (1584 to 3420) | 0.736 | 2522 (1744 to 3705) | 1714 (1302 to 2196) | 0.017 |
| CPAP duration, hours (median (IQR)) | 20 (8 to 95) | 33 (13 to 100) | 0.276 | 18 (8 to 33) | 60 (13 to 144) | 0.018 |
| CPAP level, cmH20 (median (IQR)) | 4 (4 to 4) | 4 (4 to 5) | 0.115 | 4 (4 to 4) | 4 (4 to 5) | 0.247 |
| Respiratory rate, /min (median (IQR)) | 72 (65 to 88) | 74 (59 to 82) | 0.643 | 81 (55 to 100) | 73 (59 to 90) | 0.690 |
| Leakage, L/min (median (IQR)) | 0.7 (0.4 to 1.3) | 4.3 (2.5 to 6.1) | <0.001 | 1.1 (0.7 to 1.7) | 2.7 (2.4 to 4.0) | <0.001 |
| Peak expiratory flow (median (IQR)) | −1.8 (–2.7 to −1.5) | 0.6 (–0.3 to 1.7) | <0.001 | −2.4 (–4.3 to −1.4) | 0.5 (–0.1 to 1.6) | <0.001 |
Negative peak expiratory flow indicates reversal of flow and exhalation through the system. Mann-Whitney U test used for comparisons.
GA, gestational age; nCPAP, nasal continuous positive airway pressure.