Objective To determine the level of volume targeting (VT) associated with the lowest work of breathing (WOB) for prematurely born infants being ventilated with acute respiratory distress.

Design Prospective study.

Setting Tertiary neonatal intensive care unit.

Patients 18 infants, median gestational age 29 (range 25–34) weeks, being ventilated for acute respiratory distress.

Interventions Infants were studied first without VT (baseline). Volume targeted levels of 4 ml/kg, 5 ml/kg and 6 ml/kg were then delivered in random order. After each VT level, the infants were returned to baseline. Each step was maintained for 20 minutes.

Main outcome measure The transdiaphragmatic pressure time product (PTPdi) as an estimate of the WOB.

Results The mean PTPdi was higher at a VT level of 4 ml/kg (median 154 cm H₂O·s/min) compared to baseline (median 112 cm H₂O·s/min) (p<0.001) and a VT level of 6 ml/kg (median 89 cm H₂O·s/min) (p<0.001).

Conclusion A low level of VT increased the WOB in infants with acute respiratory distress syndrome. The authors' results suggest that, during acute respiratory distress, a VT level of at least 5 ml/kg rather than a lower level might avoid an increased WOB. The most appropriate level of VT needs to be determined in a randomised controlled trial with long-term outcomes.