ESTIMATING CARDIAC OUTPUT FROM BLOOD PRESSURE AND HEART RATE: THE LILJESTRAND ZANDER FORMULA

摘要

Cardiac output (CO) is an important indicator of cardiovascular function. Several invasive and non-invasive methods havebeen developed and validated to assess CO in the clinical setting. These are often computationally complex or proprietarilyrestricted,and thus, not feasible in ambulatory investigations and the laboratory research setting. Simple mathematicaltransforms have been proposed to estimate CO from pulse pressure (PP = mean systolic blood pressure (SBP) minus meandiastolic blood pressure (DBP)), and mean heart rate (HR). Recently we evaluated one such simple technique[CO=(PPxHR)x.002], and found moderate correlation between the CO estimate and Modelflow-derived CO. Here we aimedto evaluate a more sophisticated formula, proposed in 1940 by Liljestrand and Zander. CO was estimated (COEST) dividingPP by the sum of SBP and DBP and multiplying the product by HR. This index was correlated with the Modelflow (3element Windkessel) -derived CO. Baseline beat-to-beat blood pressure data from 67 young (mean age = 19.94± 2.8), healthymen (n = 30) and women (n = 37) was available for analysis. Overall, the correlation of COEST and CO was moderate (r =.42, p <.0001) and stronger in men (r = .66, p < .0001) compared to women (r = .36, p < .05). These results suggest that atleast in some situations the Liljestrand and Zander method may provide an adequate measure of CO when other methods arenot available.