Comparison between single-beat and multiple-beat methods for estimation of right ventricular contractility

Objective: It was investigated whether pharmacologically induced changes in right ventricular contractility can be detected by a so-called “single-beat” method that does not require preload reduction. Design: Prospective animal research. Setting: Laboratory at a large university medical center. Subjects: Eight anesthetized pigs. Interventions: End-systolic elastance values obtained by a recently proposed single-beat method (Eessb) were compared with those obtained using the reference multiple-beat method (Eesmb). Measurements and Main Results: Administration of dobutamine increased Eesmb from 1.6 0.3 to 3.8 0.5 mm Hg/mL (p .001), whereas there was only a trend toward an increase in Eessb from 1.5 0.2 to 1.7 0.4 mm Hg/mL. Esmolol decreased Eesmb from 1.7 0.3 to 1.1 0.2 mm Hg/mL (p .006), whereas there was only a trend for a decrease in Eessb from 1.5 0.2 to 1.3 0.1. Conclusions: The present method using single-beat estimation to assess right ventricular contractility does not work as expected, since it failed to detect either increases or decreases in right ventricular contractility induced by pharmacologic interventions. (Crit Care Med 2004; 32:1886 –1890)