Determination of cardiac stroke volume in newborns and children under one year of age during anesthesia and surgery

To calculate cardiac stroke volume in newborns and children under one year of age during anesthesia and surgery, we used RP-2U rheograph, which had a rheostat built in, allowing to determine the baseline impedance with an accuracy of 1.0 Ohm. The time constant of the rheograph (0.05 s) made it possible to record the differential curve with insignificant influence of respiration. Electrodes were applied according to the integral rheography method. The area of each of the four electrodes was 4.2 cm2. Registration of rheographic curve was performed on three-channel electrocardiograph 3NEK-1 in parallel with phono-electrocardiogram. Cardiac stroke volume was calculated according to Kubitschek formula.