The Science Journal of the American Association for Respiratory Care

2011 OPEN FORUM Abstracts


Teresa A. Volsko1, Justin B. Hoffman1,2, Alecia M. Conger1,2, Robert L. Chatburn2; 1Health Professions, Youngstown State University, Youngstown, OH; 2Respiratory Institute, The Cleveland Clinic, Cleveland, OH

Technological advances have increased the complexity of ventilator modes, and risk of operator error. The objective of this study was to compare subtle differences in volume control (VCV) ventilation with set-point and dual targeting. Two hypotheses tested were; (1) VT delivery is different with VC using set-point versus dual targeting and (2) VC with dual targeting delivers VT similar to pressure support ventilation (PSV). METHODS: The Ingmar Medical ASL 5000 lung model was used to simulate the pulmonary mechanics of an adult patient with acute respiratory distress syndrome during active and passive ventilation. Resistance was standardized at 10 cmH2O/L/sec and compliance at 32mL/cmH2O. Active breathing was simulated with frequency (f) = 26 breaths/minute, PMus 15 cmH2O (Increase 30%, Hold 0%, and Release 25%) to produce a VT of 384 mL. VCV was initiated with the Puritan Bennett 840 (set-point targeting) and the Servo-i (dual targeting). Settings during VCV were; VT = 430 mL, mandatory f = 15 breaths/min, PEEP = 10 cmH2O, inspiratory time = 0.7, pause time = 0, inspiratory rise time = 0, flow trigger = 3 L/min. During PSV cycle threshold was set to 30% and peak inspiratory pressure was adjusted to produce a VT similar to that delivered during VCV. End expiratory tidal volume was collected on 10 consecutive breaths during active and passive breathing with VCV and PSV. Differences in mean tidal volumes (active vs passive model) were compared using ANOVA. Statistical significance was established at P < 0.05. RESULTS: Tidal volume difference varied with targeting schemes; VC set-point = 37.3 mL (+SD 3.5), VC-dual = 77.1 mL (+SD 3.3) and PSV = 406.1 mL (+SD 1.5), P < 0.001. Auto-triggering occurred during VCV set-point with active model. CONCLUSIONS: Dual targeting during VCV allows increased VT compared to set-point but not as much as PSV.
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