**3. Results**

Patient flow is shown in Figure 2, and patient demographics in Table 1. Regarding our primary endpoint, no clinically relevant changes in the rate of IH events were detected between cf- vs. vf-NCPAP or between cf-NCPAP vs. s-NIPPV (Table 2). The treatment effects (95%CI) were estimated to be 0.25 events per hour (−0.23–0.73; *n* = 10) for vf-NCPAP and −0.33 events per hour (−1.07 to 0.40; *n* = 6) for s-NIPPV. Treatment failure on the allocated device did not occur, i.e., no infant had to be intubated during the study period for apnea or bradycardia.

**Figure 2.** Patient flow; vf-NCPAP: variable flow nasal continuous positive airway pressure; s-NIPPV: synchronized nasal intermittent positive pressure ventilation; \* the attending physician decided that changing the ventilator was not advisable.

**Table 1.** Patient demographics expressed as median (minimum–maximum).


GA: gestational age; PMA: postmenstrual age.

**Table 2.** Primary and secondary endpoints expressed as median (minimum–maximum).


Comparing both continuous positive airway pressure (CPAP) modes, tcpCO2 was 3–4 mmHg lower during the vf-NCPAP or s-NIPPV support compared to cf-NCPAP, while FiO2 remained unchanged (Table 2).
