| FTC | PTC | RDS | CLD | |
| No of infants | 64 | 59 | 54 | 42 |
| No of tests* | 64 | 94 | 86 | 62 |
| 1 test occasion: n | 64 | 34 | 30 | 25 |
| 2 test occasions: n | – | 17 | 17 | 14 |
| 3 test occasions: n | – | 6 | 6 | 3 |
| 4 test occasions: n | – | 2 | 1 | – |
| Details from last test occasion in each infant | ||||
| PMA (weeks) | 44.2 (1.4) | 40.2 (4.1) | 39.7 (4.3) | 41.3 (3.8) |
| Weight (kg) | 4.37 (0.54) | 3.10 (1.00) | 2.91 (0.90) | 3.16 (0.91) |
| Weight z score22 | 0.09 (0.78) | −0.92 (1.08) | −1.11 (1.06) | −1.26 (1.31) |
| Length (cm) | 54.6 (2.8) | 48.7 (4.3) | 47.8 (4.6) | 47.5 (3.9) |
| Length z score22 | 0.29 (1.12) | −1.06 (1.32) | −1.38 (1.39) | −2.2 (1.35) |
| BMI | 14.6 (1.3) | 12.7 (2.3) | 12.4 (1.8) | 13.7 (2.0) |
| BMI z score | −0.55 (1.10) | −0.54 (0.98) | −0.34 (1.18) | 0.16 (1.27) |
| FRC (ml) | 79.6 (14.5) | 64.3 (15.6) | 59.2 (16.6) | 53.5 (15.3) |
| FRC (ml/kg) | 18.4 (3.6) | 22.1 (6.0) | 21.2 (5.4) | 17.5 (4.8) |
| LCI | 7.17 (0.54) | 7.14 (0.88) | 6.89 (0.74) | 7.56 (1.12) |
| M1/M0 | 2.12 (0.21) | 2.08 (0.26) | 1.99 (0.20) | 2.22 (0.32) |
| M2/M0 | 8.14 (2.47) | 7.70 (2.18) | 6.97 (1.48) | 8.96 (2.82) |
| Vt (ml) | 29.7 (5.9) | 21.8 (7.0) | 19.1 (7.0) | 18.7 (6.1) |
| Vt (ml/kg) | 6.8 (1.3) | 7.2 (1.2) | 6.6 (1.5) | 6.0 (1.0) |
| RR (/min) | 47 (12) | 53 (13) | 53 (14) | 59 (16) |
| MV (ml/kg) | 311 (57) | 362 (87) | 336 (74) | 345 (83) |
Results are expressed as mean (SD).
*Total number of tests used for multivariable and multilevel analysis.
BMI, body mass index; CLD, chronic lung disease; FRC, functional residual capacity; FTC, full term controls; LCI, lung clearance index; M1/M0 and M2/M0, 1st and 2nd moment ratios; MV, minute volume; PMA, postmenstrual age; PTC, preterm controls; RDS, respiratory distress syndrome; RR, respiratory rate; Vt, tidal volume.