Flow-cycled versus time-cycled sIPPV in preterm babies with RDS: a breath to breath randomised cross-over trial

Abstract

Objectives: Few data exist about patient triggered ventilation techniques in neonatal critical care. Our aim was to compare pressure limited sIPPV in the classical time cycled (TC-sIPPV) mode against flow cycled (FC-sIPPV) modality. In this latter, typical sIPPV full respiratory support is provided but both the initiation and the end of inflation are determined by the infant’s spontaneous respiratory efforts by using airway flow changes.

Setting: A 3rd level neonatal intensive care unit. Patients and intervention. Ten preterm babies (< 32 wks gestation) were randomised to receive 1h FC-sIPPV followed by 1h TC-sIPPV or the inverse shift, according to a computer created randomization table. Eligible babies had hyaline membrane disease and received 200 mg/kg surfactant at least 6 hours before the study period. Respiratory mechanics, ventilatory and vital parameter data were registered real time.

Results: FC-sIPPV resulted in lower rate-volume ratio, pressure x rate product, mean airway pressure and heart rate; tidal volume and oxygen saturation were higher (all p<0.0001). Spontaneous inspiratory time was lower than usually set by the physician and it was directly correlated to birth weight (rho = 0.5, p=0.001) and gestational age (rho = 0.32, p=0.001). No differences were noticed in the mechanics and blood gas and vital parameters during the two study phases.

Conclusions: FC-sIPPV may safely result in a better patient ventilator synchrony. Inspiratory time usually set in neonatal critical care is higher than the one decided by the baby during spontaneous effort. This should be considered when establishing time cycled ventilation.