Work of breathing and volume targeted ventilation in respiratory distress.

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 H(2)O·s/min) compared to baseline (median 112 cm H(2)O·s/min) (p<0.001) and a VT level of 6 ml/kg (median 89 cm H(2)O·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.