CLINICAL-APPLICATION OF VENTRICULAR END-SYSTOLIC ELASTANCE AND THE VENTRICULAR PRESSURE-VOLUME DIAGRAM

The ability to clinically assess myocardial contractility in a load-in dependent fashion facilitates the selection of appropriate inotropes, when needed, during shock resuscitation. Within the framework of the v entricular pressure-volume diagram, the slope of the ventricular end-s ystolic pressure-volume relationship (expressed as ventricular end-sys tolic elastance, E-es), has been shown to accurately reflect ventricul ar inotropic state, and to be insensitive to loading conditions. It ha s not, however, been widely used at the bedside. Our goal was to evalu ate the clinical utility of E-es and the ventricular pressure-volume d iagram as bedside methods of hemodynamic assessment. We performed a pr ospective study of 123 hemodynamic interventions in 100 trauma patient s during shock resuscitation in which contractility (E-es), preload (l eft ventricular end-diastolic volume index), and afterload (effective arterial elastance) were calculated before and after addition of inotr opes, fluid bolus, and afterload reduction. Mean values of each variab le were compared before and after each type intervention using the pai red t test. The ventricular pressure-volume diagram was used to predic t changes in the studied variables, and the experimental results were compared with predicted changes. E-es (mmHg/mL/m(2)) increased signifi cantly with inotropes (4.7 +/- 3.2 to 10 +/- 8.7, p < .0001), but was not affected by clinically significant fluid administration (7.0 +/- 4 .7 to 8.3 +/- 8.0, p = .10) or afterload reduction (9.6 +/- 5.2 to 9.2 +/- 4.7, p = .72). Left ventricular end-diastolic volume index (mL/m( 2)) improved with fluid administration (54 +/- 8.9 to 62 +/- 9.8, p < .0001) and effective arterial elastance (mmHg/mL/m(2)) decreased with afterload reduction (3.3 +/- .9 to 2.6 +/- .7, p < .0001). We conclude that E-es is a load-independent measure of contractility, which is me asurable at the bedside. The pressure-volume diagram is a useful metho d of monitoring hemodynamic changes associated with interventions duri ng shock resuscitation.