Lung recruitment and breathing pattern during variable versus continuous flow nasal continuous positive airway pressure in premature infants: An evaluation of three devices

Objective. To determine whether lung volume changes and breathing pattern p arameters differ among 3 devices for delivery of nasal continuous positive airway pressure (CPAP) in premature infants. Methods. Thirty-two premature infants receiving nasal CPAP for apnea or mil d respiratory distress were enrolled. Birth weight was (mean +/- standard d eviation) 1081 +/- 316 g, gestational age 29 +/- 2 weeks, age at study 13 /- 12 days, and fraction of inspired oxygen (FIO2)at study .29 +/- .1. Thre e devices, applied in random order, were studied in each infant: continuous flow nasal CPAP via CPAP prongs, continuous flow nasal CPAP via modified n asal cannula, and variable flow nasal CPAP. After lung recruitment to stand ardize volume history, changes in lung volume (DeltaV(L)) were assessed at nasal CPAP of 8, 6, 4, and 0 cm H2O using calibrated direct current-coupled respiratory inductance plethysmography. Results. DeltaV(L) was significantly greater overall with the variable flow device compared with both the nasal cannula and CPAP prongs. However, Delt aV(L) was not different between the cannula and the prongs. Respiratory rat e, tidal volume, thoraco-abdominal asynchrony, and FIO2 were greater with t he modified cannula than for either of the other 2 devices. Conclusion. Compared with 2 continuous flow devices, the variable flow nasa l CPAP device leads to greater lung recruitment. Although a nasal cannula i s able to recruit lung volume, it does so at the cost of increased respirat ory effort and FIO2.