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

OBJECTIVES: To assess the work of breathing at different levels of volume targeting in prematurely born infants with evolving or established bronchopulmonary dysplasia (BPD).

DESIGN: Randomised crossover study.

SETTING: Tertiary neonatal intensive care unit.

PATIENTS: Eighteen infants born at <32 weeks gestation who remained ventilated at or beyond 1 week after birth, that is, they had evolving or established BPD.

INTERVENTIONS: Infants 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 MEASURES: Pressure-time product of the diaphragm (PTPdi), a measure of the work of breathing, at different levels of volume targeting.

RESULTS: The 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).

CONCLUSIONS: Only 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.