The Effect of Targeting Scheme on Tidal Volume Delivery During Volume Control Mechanical Ventilation

BACKGROUND: Technological advances have increased ventilator mode complexity and risk of operator error. OBJECTIVE: To compare differences in volume control (VC) ventilation with set-point and dual targeting. Two hypotheses were tested: tidal volume (V-T) delivery is different with VC using set-point versus dual targeting during active versus passive breathing; VC with dual targeting delivers V-T similar to pressure support ventilation (PS) with active breathing. METHODS: The Ingmar Medical ASL 5000 lung model simulated pulmonary mechanics of an adult patient with ARDS during active and passive ventilation. Resistance was standardized at 10 cm H2O/L/s and compliance at 32 mL/cm H2O. Active breathing was simulated by setting the frequency (f) = 26 breaths/min, and adjusting the muscle pressure (P-mus) to produce a V-T of 384 mL. VC was initiated with the Puritan Bennett 840 (set-point targeting) and the Servo-i (dual targeting) at V-T = 430 mL, mandatory f = 15 breaths/min, and PEEP = 10 cm H2O. During PS, cycle threshold was set to 30% and peak inspiratory pressure adjusted to produce a V-T similar to that delivered during VC. Expiratory V-T was collected on 10 consecutive breaths during active and passive breathing with VC and PS. Mean V-T differences (active vs passive model) were compared using analysis of variance. Statistical significance was established at P < .05. RESULTS: The mean +/- SD V-T difference varied with targeting schemes: VC set-point = 37.3 +/- 3.5 mL, VC-dual = 77.1 +/- 3.3 mL, and PS = 406.1 +/- 1.5 mL (P < .001). Auto-triggering occurred during VC set-point with the active model. CONCLUSIONS: Dual targeting during VC allows increased V-T, compared to set-point, but not as much as PS.