Duration of apnoea before start of backup ventilation during nCPAP in extremely preterm infants and time spent within the SpO2 target: a randomised cross-over study.

Objective: Central apnoea due to immaturity of the respiratory drive constitutes the main cause of frequent and prolonged desaturations in extremely preterm (EPT) infants <28 weeks. We investigated the impact of varying the duration of apnoea before backup ventilation (BUV) on the measures of oxygenation in EPT infants during nasal continuous positive airway pressure (nCPAP) therapy.

Design: Single-centre randomised cross-over trial.

Setting: Level 3 neonatal intensive care unit.

Patients: 24 EPT infants on nCPAP with BUV.

Main outcome measures: The primary outcome was the time spent within a predefined oxygen saturation (SpO₂) target (88%-95% or ≥88% with fraction of inspired oxygen (FiO₂) =0.21) during start of BUV after 4 s of apnoea duration (AD 4) or 16 s of apnoea duration (AD 16) RESULTS: The study was successfully completed in 22 children (median gestational age 24+5 weeks, birth weight 628 g, postnatal age 48 days). Mean time spent within the SpO₂ target didn't differ between AD 4 and AD 16 (66.9% vs 67.2%, p=0.88). There were no differences in the time below or above the SpO₂ target, prolonged (>30 s, >60 s, >120 s) and severe (<80%, <70%) episodes of hypoxaemias and cerebral tissue oxygenation. Mean FiO₂, mean airway pressure, transcutaneous carbon dioxide pressure, heart rate and respiratory frequency did not differ while the rate of BUV was significantly higher during AD 4.

Conclusion: Reducing the time of apnoea until start of BUV didn't improve the time spent within the SpO₂ target in respiratory unstable EPT infants. Our data demand intensified efforts to specify these settings of non-invasive respiratory support that better achieve this important clinical goal.

Trial registration number: DRKS00031911.