Difference in inspiratory flow between volume and pressure control ventilation in patients with flow dyssynchrony.

PURPOSE

Flow dyssynchrony is common during volume control ventilation but minimized during pressure control. Characterizing inspiratory flow during pressure control breaths can inform adjustments of the fixed flow of volume control to address flow dyssynchrony. This study compared inspiratory flow peak and pattern between volume control and adaptive pressure control breaths.

MATERIAL AND METHODS

Subjects with or at risk for ARDS were ventilated with volume control decreasing ramp flow at different tidal volumes and subsequently with adaptive pressure control targeting those same tidal volumes. Inspiratory flows of volume control breaths exhibiting flow dyssynchrony, and those of pressure control breaths at the same set tidal volumes without flow dyssynchrony were analyzed, for a total of 17 subject-tidal volume conditions. Peak flow and flows at 10, 25, 50 and 75% of inspiratory time were compared between modes.

RESULTS

Group peak flows were not different between modes, but at 50 and 75% of inspiratory time flows were higher during adaptive pressure control. In 8 subject-tidal volume conditions V were higher (>1ml/kg PBW) on adaptive pressure control than on volume control.

CONCLUSIONS

In patients with flow dyssynchrony during volume control ventilation, adjustment of inspiratory flow pattern should be considered to minimize this dyssynchrony.