COMPARISON OF THE 3 DIFFERENT FORMULAS FOR DOPPLER ESTIMATION OF PULMONARY-ARTERY SYSTOLIC PRESSURE

Noninvasive pulmonary artery systolic pressure (PASP) is calculated by summing the right ventricular systolic pressure obtained from Doppler velocity of regurgitant flow through the tricuspid valve and the righ t atrial (RA) pressure. The RA pressure is generally assumed from diff erent formulas. An accurate KA pressure estimation will add precision to PASP calculation. One of the methods to estimate RA pressure is the inferior vena cava collapsibility index (IVCCI). In 45 patients refer red for right heart catheterization, the authors tested a formula for the calculation of PASP based on the estimation of RA pressure from IV CCI and compared this method with two other formulas. The first method (method 1) assumed a constant RA pressure of 10 mm Hg irrespective of right ventricular pressure. The formula used was Doppler gradient + 1 0 (mm Hg). In the second method (method 2), a clinical estimate of RV pressure was made from the formula: right ventricular-right atrial Dop pler gradient x 1.1 + 14. In the third method (method 3), the patients were classified into three groups on the basis of IVCCI: group A, IVC CI greater than 45%; group B, IVCCI between 35% and 45%; and group C, IVCCI less than 35%, The formula used was Doppler gradient + 6, 9, or 16 mm Hg in the presence of normal (group A), moderately reduced (grou p B), or markedly reduced (group 3) IVCCI. A good correlation between Doppler and catheter measurements of PASP was found for methods 1, 2, and 3, respectively (r = 0.8933, SEE = 6.4, r = 0.8921, SEE = 7.0, and r = 0.8989, SEE = 6.7). Correlation between invasive and noninvasive PASP was similar with the three methods, but correlation in method 2 w as less satisfactory than with the other two methods. The mean differe nce between Doppler-derived and hemodynamic PASP was also high in meth od 2. In conclusion, the result of this study validates a relatively n ew, simple echo-Doppler formula for Doppler estimation of PASP based o n a noninvasive evaluation of RA pressure through the IVCCI. However, this method is not better than the traditional method 1 for noninvasiv e PASP estimation.