Objectives To determine the impact of different volume-targeted (VT) levels during volume-targeted ventilation (VTV) on the work of breathing (WOB) of infants born at or near term and to investigate whether a level of VT reduced the WOB below that experienced on respiratory support without VT.

Design Prospective crossover study.

Patients Sixteen infants, median gestational age of 38 (range 34–41) weeks, birth weight of 3.1 (range 1.5–4.1) kg and postnatal age of 5 (range 2–17) days were studied. The infants were receiving time-cycled, pressure-limited ventilation in a continuous mandatory or in a triggered mode.

Interventions The infants were studied first without VT (baseline) and then at VT levels of 4, 5 and 6 ml/kg delivered in a random order. After each VT level, the infants were returned to baseline.

Main outcome measure The WOB was assessed by measuring the transdiaphragmatic pressure-time product (PTPdi).

Results One infant became apnoeic at VT of 6 ml/kg. At a VT level of 4 ml/kg, four infants were making such vigorous respiratory efforts that no inflations were delivered. The median PTPdi was higher at a VT level of 4 ml/kg than at 5 ml/kg (p<0.01) or 6 ml/kg (p<0.001). Only at a VT level of 6 ml/kg was the median PTPdi lower than that at baseline (p<0.01).

Conclusion Low VT levels (4 ml/kg) during VTV increase the WOB in ventilated infants born at term or near term. The results suggest that a VT level of 6 ml/kg could be used to reduce the WOB.