BACKGROUND: Asynchrony between the very low birthweight (VLBW) baby's spontaneous efforts and ventilator-delivered breaths may result in inefficient gas exchange, pneumothorax, and variability in cerebral blood flow. METHODS & MATERIALS: We evaluated the short-term application of a flow-actuated device (Ventilator Flow Synchronizer, Bird Products Corp, Palm Springs CA) for trig- gering an otherwise time-cycled, pressure-limited ventilator, in 10 stable VLBW infants. Variables at the end of 2 1-hour periods of conventional intermittent man- datory ventilation were compared to the same variables at the end of 1 hour of flow-synchronized ventilation (FSV). RESULTS: Mechanical rate and minute ven- tilation increased with FSV. PaO2 rose significantly, but no change was seen in PaCO2. No significant changes were seen in mean airway pressure or mechanical tidal volume, and no adverse reactions or mechanical malfunctions were observed. CONCLUSION: Short-term evaluation suggests that FSV is safe and feasible in stable VLBW babies. (Respir Care 1992;37:249-253).