END-DIASTOLIC VOLUME VERSUS PULMONARY-ARTERY WEDGE PRESSURE IN EVALUATING CARDIAC PRELOAD IN TRAUMA PATIENTS

Objective: To evaluate the relative accuracy of right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery wedge pressure (PAWP) for determining cardiac preload. Methods: A modified pulmonary artery catheter was used to determine RVEDVI, PAWP, and CI 238 times in 32 trauma patients. Results: The initial mean values included cardiac index (CI) = 3.4 +/- 1.3 L/min/m(2), PAWP = 14.8 a 6.6 mm Hg, and RVEDVI = 99 +/- 40 mL/m(2). Cardiac index correlated better with RVEDVI (r = 0.6440; p < 0.001) than with PAWP (r = 0.1068) or CVP (r = 0.1604). In 84 studies in 19 patients, the PAWP was high (19+ mm Hg) in spite of an RVEDVI that was low (<90 mL/m(2)) in 22 (26%) or mid-range (90-140 mL/m(2)) in 49 (58%) of these. In addition, in 12 studies a high RVEDVI (>140 mL/m(2)) existed with a relatively low PAWP (<12 mm Hg). Thus, in 83 (35%) of the studies, PAWP provided information different from the RVEDVI. Of 65 instances in which preload was increased, CI ''responded'' (greater than or equal to 20%) in 26 (40%). The incidence of a response was not affected by the PAWP; however, responses with a RVEDVI of <90, 90-140, or >140 mL/m(2) were 64%, 27%, and 0 (p < 0.001). Conclusion: The RVEDVI more accurately predicted preload recruitable increases in CI than did the PAWP.