• Jens A Broscheit, Clemens A Greim, Manuel Kessler, Frank Weidemann, and Norbert Roewer.
• Department of Anesthesiology, University of Wuerzburg, Josef-Schneider-Strasse 2, D-97080 Wuerzburg, Germany. jbroscheit@anaesthesie.uniwuerzburg.de
• J. Cardiothorac. Vasc. Anesth. 2004 Aug 1; 18 (4): 415-22.

ObjectiveThe authors investigated the feasibility of an online sampling and display of LV flow-area loops for the determination of LV elastance and preload-recruitable stroke work (PRSW). Automated LV area measurements by echocardiography may be combined with flow velocity measurements in the internal carotid artery to construct LV flow-area loops as estimates of the systolic pressure-volume relationship.SettingUniversity hospital.DesignOpen chest model.ParticipantsEight anesthetized minipigs.InterventionsInferior vena cava occlusion was performed to simultaneously obtain parameters of the LV flow-area relationship and the LV pressure-area relationship.Measurements And Main ResultsParameters were obtained at baseline and during sequential administration of dobutamine (5 microg/kg/min) and halothane (0.8 vol%). Linear regression analysis and analysis of variance were performed to investigate an underlying linear relationship between the corresponding variables. Highly linear elastance and PRSW curves were derived from the flow-area and pressure-area loops (n = 24, R >/= 0.85). Changes of the curve slopes indicated inotropic changes as well as model independent dP/dt(max). Elastance from the pressure-area relationship was expressed by elastance from the flow-area relationship by the term y = 0.52 + 0.04. x (R(2) = 0.84; p < 0.0001). Linear regression of PRSW as derived from the flow-area relationship with PRSW as derived from the pressure-area relationship was expressed by y = 0.43 + 0.02. x (R(2) = 0.77; p < 0.0001).ConclusionIndices of the LV pressure-area relationship can be derived from real-time loops constructed from arterial flow velocity and LV area.

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