Clinical characteristics of group I infants compared with those of group II infants (mean (SD))
| Criteria | Group I (n=9) | Group II (n=7) | P value |
| Birthweight | 3.5 (0.5) | 2.9 (1.0) | NS |
| Gestaional age (weeks) | 40.2 (1.0) | 37.9 (5.4) | NS |
| PaO2 before INO (mm Hg) | 31.9 (14.4) | 27.0 (9.3) | NS |
| PaO2before weaning NO (mm Hg) | 68.1 (20) | 60.1 (17.6) | NS |
| Duration of INO (hours) | 84 (51) | 90 (42) | NS |
NS=not significant.