Comparison between pressure-recording analytical method (PRAM) and femoral arterial thermodilution method (FATD) cardiac output monitoring in an infant animal model of cardiac arrest

BACKGROUND The pressure-recording analytical method is a new semi-invasive method for cardiac output measurement (PRAM). There are no studies comparing this technique with femoral artery thermodilution (FATD) in an infant animal model. METHODS A prospective study was performed using 25 immature Maryland pigs weighing 9.5 kg. Fifty-eight simultaneous measurements of cardiac index (CI) were made by FATD and PRAM at baseline and after return of spontaneous circulation. Differences, correlation, and concordance between both methods were analyzed. The ability of PRAM to track changes in CI was explored with a polar plot. RESULTS Mean CI measurements were 4.5 L/min/m(2) (95 % CI, 4.2-4.8 L/min/m(2); coefficient of variation, 27 %) by FATD and 4.0 L/min/m(2) (95 % CI, 3.6-4.3 L/min/m(2); coefficient for variation, 37 %) by PRAM (difference, 0.5 L/min/m(2); 95 % CI for the difference, 0.1-1.0 L/min/m(2); p = 0.003; n = 58). No correlation between both methods was observed (r = 0.170, p = 0.20). Limits of agreement were -2.9 to 4.0 L/min/m(2) (-69.9 to 84.9 %). Percentage error was 80.6 %. Only 26.1 % of data points lied within an absolute deviation of ±30° from the polar axis. CONCLUSIONS No correlation nor concordance between both methods was observed. Limits of agreement and percentage of error were high and clinically not acceptable. No concurrence between both methods in CI changes was observed. PRAM is not a useful method for measurement of the CI in this pediatric model of cardiac arrest.