Abstract
BACKGROUND:
Pressure-control ventilation (PCV) and pressure-regulated volume-control (PRVC) ventilation are used during lung-protective ventilation because the high, variable, peak inspiratory flow rate (V˙I) may reduce patient work of breathing (WOB) more than the fixed V˙I of volume-control ventilation (VCV). Patient-triggered breaths during PCV and PRVC may result in excessive tidal volume (VT) delivery unless the inspiratory pressure is reduced, which in turn may decrease the peak V˙I. We tested whether PCV and PRVC reduce WOB better than VCV with a high, fixed peak V˙I (75 L/min) while also maintaining a low VT target.
METHODS:
Fourteen nonconsecutive patients with acute lung injury or acute respiratory distress syndrome were studied prospectively, using a random presentation of ventilator modes in a crossover, repeated-measures design. A target VT of 6.4 ± 0.5 mL/kg was set during VCV and PRVC. During PCV the inspiratory pressure was set to achieve the same VT. WOB and other variables were measured with a pulmonary mechanics monitor (Bicore CP-100).
RESULTS:
There was a nonsignificant trend toward higher WOB (in J/L) during PCV (1.27 ± 0.58 J/L) and PRVC (1.35 ± 0.60 J/L), compared to VCV (1.09 ± 0.59 J/L). While mean VT was not statistically different between modes, in 40% of patients, VT markedly exceeded the lung-protective ventilation target during PRVC and PCV.
CONCLUSIONS:
During lung-protective ventilation, PCV and PRVC offer no advantage in reducing WOB, compared to VCV with a high flow rate, and in some patients did not allow control of VT to be as precise.
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