Volume targeting levels and work of breathing in infants with evolving or established bronchopulmonary dysplasia

Abstract

ObjectivesTo assess the work of breathing at different levels of volume targeting in prematurely born infants with evolving or established bronchopulmonary dysplasia (BPD).DesignRandomised crossover study.SettingTertiary neonatal intensive care unit.PatientsEighteen infants born at <32 weeks gestation who remained ventilated at or beyond 1 week after birth, that is, they had evolving or established BPD.InterventionsInfants received ventilation at volume targeting levels of 4, 5, 6 and 7 mL/kg each for 20 minutes, the levels were delivered in random order. Baseline ventilation (without volume targeting) was delivered for 20 minutes between each epoch of volume-targeting.Main outcome measuresPressure-time product of the diaphragm (PTPdi), a measure of the work of breathing, at different levels of volume targeting.ResultsThe 18 infants had a median gestational age of 26 (range 24–30) weeks and were studied at a median of 18 (range 7–60) days. The mean PTPdi was higher at 4 mL/kg than at baseline, 5 mL/kg, 6 mL/kg and 7 mL/kg (all P≤0.001). The mean PTPdi was higher at 5 mL/kg than at 6 mL/kg (P=0.008) and 7 mL/kg (P<0.001) and higher at 6 mL/kg than 7 mL/kg (P=0.003). Only at 7 mL/kg was the PTPdi significantly lower than at baseline (P=0.001).ConclusionsOnly a tidal volume target of 7 mL/kg reduced the work of breathing below the baseline and may be more appropriate for infants with evolving or established BPD who remained ventilator dependent at or beyond 7 days of age.