Comparison of groups by time to threshold ECO2 >2%
| Category of time to ECO2 >2% | Kruskal-Wallis test * | |||
| A: ECO2 >2% in first ventilation | B: ECO2 >2% during ventilation | C: ECO2 >2% never achieved | P value | |
| n | 113 | 298 | 23 | – |
| Expired tidal volume, VTE (mL/kg) | 7.3 (4.3–11.3) | 4.2 (1.9–7.4) | 2.9 (1.0–5.0) | <0.001* |
| Mask leak (%) | 41 (25–60) | 55 (36–43) | 78 (44–93) | <0.001† |
| Ventilation frequency (per minute) | 45 (33–61) | 48 (38–69) | 64 (46–73) | 0.009‡ |
| Peak inflation pressure (mbar) | 35 (31–39) | 36 (31–39) | 33 (25–38) | 0.16 |
| Minute volume (mL/kg per minute) | 325 (171–553) | 201 (82–421) | 154 (51–406) | <0.001§ |
| Birth weight (kg) | 3.2 (2.9–3.5) | 3.1 (2.7–3.4) | 2.9 (2.6–3.2) | <0.001¶ |
| First detected heart rate (bpm) | 70 (59–94) | 67 (56–85) | 77 (59–83) | 0.15 |
| Apgar 1 min | 7 (6–7) | 6 (5–7) | 5 (5–7) | <0.001** |
| Apgar 5 min | 10 (8–10) | 10 (8–10) | 9 (7–10) | 0.19 |
| Time from first to last ventilation (s) | 126 (63–258) | 217 (95–458) | 66 (22–130) | <0.001†† |
All values are medians (IQR). For ventilation factors, we used median per group of medians per newborn within the first 30 s of ventilation. Kruskal-Wallis test was performed to rank medians. The column shows p values for comparison of all three groups, p values for significant differences between groups compared in pairs are given as footnotes.
*VTE: A≠B (p<0.001), A≠C (p<0.001), B≠C (p=0.07).
†Mask leak: A≠B (p<0.001), A≠C (p<0.001), B≠C (p=0.04).
‡Ventilation frequency: A≠B (p=0.02), A≠C (p=0.008), B≠C (p=0.07).
§Minute volume: A≠C (p=0.009), B≠C (p<0.001).
¶Birth weight: A≠B (p<0.001), A≠C (p=0.010).
**Apgar at 1 min: A≠B (p<0.001), A≠C (p=0.017).
††Time from first to last ventilation: A≠B (p=0.023), A≠C (p<0.001), B≠C (p>0.001).