Background and aims Although CPAP is extensively used for early RDS in very preterm infants from birth, the influence of CPAP on lung behaviour in early illness remains unclear. This study aimed to describe global volumetric behaviour and work of breathing (WOB) at differing continuous distending pressures (CDP) in very preterm infants in the first 12–18 hrs of life.
Methods Infants < 32 weeks’ gestational age receiving nasal CPAP from birth were studied whilst supine. Data were initially recorded at the CPAP in clinical use [baseline; mean (SD) 6(1) cmH2O, FiO2 0.25(0.03)]. Then, CPAP was applied at 5, 8, 10 and 8 cmH2O for 15-mins each. Changes in end-expiratory lung volume [ΔEELV (VT units)] and tidal volume [ΔVT (VT units)] were measured using respiratory inductive plethysmography and expressed relative to values obtained at CPAP 5 cmH2O. Breath-to-breath phase angles (Θ) and labour breathing index (LBI) were calculated post-hoc to determine respiratory asynchrony.
Results Twenty infants, mean(SD) GA 29(1) weeks and BW 1181(417)g were studied at median (IQR) 15(13.16)hours. No significant differences were seen in global EELV, V T, WOB or LBI at all CDP. Only 11/20 infants demonstrated hysteresis with a significant increase in EELV from baseline following a CPAP recruitment manoeuvre.
Conclusions Not all preterm infants have recruitable lung disease. Infants with recruitable lung disease may benefit from a CPAP recruitment manoeuvre. Further work is needed to define the optimal CPAP level to use in early RDS.