The effect of heart rate and pulse pressure on mean arterial pressure: the combined formula for calculation of mean arterial pressure.

BACKGROUND We demonstrate a new formula to predict mean arterial pressure (MAP) using corrections of the key factors associated with the inaccuracy of the standard formula: heart rate (HR) and pulse pressure (PP). METHODS A total of 99 patients (50 men, 49 women; mean age 52.5 ± 10.3 years), who underwent elective coronary angiography, were enrolled in our study. The arterial pressure was measured in the aortic root. MAP was measured digitally by the area-under-the-pressure-time curve method. We evaluated the accuracy of four different formulas: the standard formula, the formula of Razminia et al., the formula of Meaney et al. and the combined formula. RESULTS PP coefficient deviation of the standard formula was negatively correlated with PP (R = -0,561, P < 0.001), and positively correlated with HR (R = 0,298, P = 0.003). Both R and R2 values of the combined formula were higher than previous formulas. Accuracy parameters of the combined formula [root mean square error (RMSE): 1.801 mmHg, mean square residuals (MSR): 3.244 mmHg2, Akaike information criterion (AIC): 401.4] were superior to the standard formula (RMSE: 1.902 mmHg, MSR: 3.620 mmHg2, AIC: 412.3), the formula of Razminia et al. (RMSE: 2.022 mmHg, MSR: 4.089 mmHg2, AIC: 424.3) and the formula of Meaney et al. (RMSE: 2.137 mmHg, MSR: 4.568 mmHg2, AIC: 435.3). In the multivariate linear regression analysis, the combined formula was the only method that independently predicts the measured MAP (beta = 0,990, P < 0.001). CONCLUSION The combined formula is superior to previous formulas for accurately predicting MAP.