Volume targeted versus pressure limited ventilation in term born infants

Abstract

Background: During volume targeted ventilation (VTV) a relatively constant volume is delivered with each ventilator volume regardless of changes in the infant's lung function.

Aims and objectives: To determine whether VTV or pressure limited ventilation (PLV) was associated with a shorter time to successful extubation and if any difference was explained by a lower work of breathing (WOB), better respiratory muscle strength or less thoraco-abdominal asynchrony (TAA) and was associated with fewer episodes of hypocarbia.

Methods: A prospective randomised trial was undertaken. Infants born at >34 weeks of gestational age and ventilated <24 hours in the first two weeks after birth were randomised to either VTV or PLV. The time to extubation was determined. The WOB was assessed by the transdiaphragmatic pressure time product, respiratory muscle strength by the maximum inflation (Pimax) and expiratory (Pemax) pressures and TAA assessed using uncalibrated respiratory inductance plethysmography.

Results: Forty infants, median gestational age 39 (range 34-42) weeks were recruited. The time to successful extubation did not differ significantly between the two groups (25, range 2.5-312 hours (VTV) versus median 33.5, range 1-312 hours (PLV)) p=0.461. There were no significant differences between the groups with regard to the WOB, respiratory muscle strength or the TAA results. In the VTV group there was a median of 1.5 (range 0-8) and in the PLV group a median of 4 (range 1-13) episodes of hypocarbia (p=0.005).

Conclusions: In infants born at or near term, VTV compared to PLV did not reduce the time to successful extubation, but was associated with significantly fewer episodes of hypocarbia.