Randomised Trial Comparing Assist Control Ventilation to Pressure Support Ventilation During Weaning

Objectives: To test the hypothesis that the duration of weaning would be shorter using assist control ventilation (ACV) rather than pressure support ventilation (PSV). To determine if any differences in the duration of weaning reflected differences in the work of breathing, the rate of asynchrony or the level of respiratory muscle strength.

Patients and methods: Thirty-six infants, median gestational age 29 (range 24 to 39) weeks, were randomized to weaning by either ACV or PSV. The duration of weaning was recorded. At baseline (study entry), 24 hours after entering the study and immediately prior to extubation, the work of breathing was assessed by measuring the transdiaphragmatic pressure time product (PTPdi), thoracoabdominal asynchrony (TAA) was assessed using respiratory inductance plethysmography and respiratory muscle strength measured by recording the maximal inspiratory pressure produced during an airway occlusion during crying (Pimax). Immediately prior to extubation, the level of active expiration was also assessed.