[Quantitative aortic flow and cardiac output volume determinations in rabbits using tetrapolar impedance...

In 25 normal rabbits the transthoracic impedance changes were continually registered at rest and during pharmacological exercise by use of various types of electrodes. These changes were quantified by the formula of Kubicek for estimation of cardiac output. The obtained values were compared with the values of cardiac output and the flow in the aorta descendens measured by electromagnetic flowmetry in the aorta descendens. Linear regression analyses for several intervals of ejection and various types of electrodes showed a high and significant correlation between the values estimated by both methods (r greater than or equal to 0.96, p less than or equal to 0.001). The analyses of confidence intervals of the parameters of linear regression showed that the functional relations can be described by uniform parameters of regression. On this basis were estimated coefficients of correction which allow quantitative evaluation of the cardiac output and the flow in the aorta descendens in rabbits by use of tetrapolar impedance plethysmography. For cardiac output: (Formula: see text) for the flow in the aorta descendens: (Formula: see text) Tetrapolar impedance plethysmography is a noninvasive method, which allows quantitative and dynamic evaluation both of the cardiac output and the flow in the aorta descendens in rabbits.