Validation of Cardiac Output Measurements with Noninvasive Doppler Echocardiography by Thermodilution and Fick Methods in Newborn Piglets

Abstract

Since cardiac output measured by the noninvasive pulsed Doppler technique has not been well correlated to results from the invasive thermodilution or Fick methods in neonates, the three methods were evaluated in 6 sedated newborn piglets (age < 7 days, weight 1.5 ± 0.7 kg) in room air and after 10 min of hypoxia. Doppler velocities were measured in the ascending aorta, and the aortic root diameter was measured in early diastole. A Swan-Ganz catheter in the left pulmonary artery sampled mixed venous blood for central venous O₂ content and measured cardiac output by thermodilution. Oxygen consumption was measured by the open-circuit technique and used to determine cardiac output by the Fick method. In room air, values obtained by pulsed Doppler, thermodilution and Fick methods (0.270 ± 0.05, 0.246 ± 0.05 and 0.241 ± 0.05 liters/kg/min, respectively) were similar, with a correlation coefficient (r) between Doppler and thermodilution values of 0.89, Doppler and Fick values of 0.82 and thermodilution and Fick values of 0.88. Although hypoxia sometimes produced larger differences between paired values, correlation coefficients remained high (Doppler echocardiography vs. thermodilution, r = 0.96; Doppler vs. Fick methods, r = 0.92; thermodilution vs. Fick method, r = 0.95). The mean ± SD of the percent difference between values obtained by Doppler echocardiography and thermodilution was 4.2 ± 14.4% in room air and 12.8 ± 14.4% in hypoxia, whereas differences in values obtained by Doppler and Fick methods was 6 ± 14.9% in room air and 14.7 ± 8.5% with hypoxia. We conclude that pulsed Doppler echocardiography correlates well with the standard invasive methods for measuring cardiac output during normoxia and hypoxia in newborns, but a greater variability between individual results is sometimes seen during hypoxia.

Left ventricle output and mean arterial blood pressure in preterm infants during the 1st day of life

“…Nevertheless, it has been shown to compare favourably with measures taken from invasive methods of assessing cardiac output in both human infants and newborn piglets [22,40]. We used the results of oscillometric method in the analysis of blood pressure measurements.…”

Effects of blood transfusion on left ventricular output in premature babies

“…In order to obtain more accurate measurement, different sites have been suggested by various investigators to measure these parameters. [7,8,12,13] In the present study, comparison was made on mean measurements at three different times obtained from the same baby by the same investigator using a consistent approach and thus the results were unlikely to have been affected by the measuring method.…”

Effects of a Nebulized NONOate, DPTA/NO, on Group B Streptococcus–Induced Pulmonary Hypertension in Newborn Piglets

“…CO was measured by thermodilution using a CO computer (Model 9510-A; Edwards Laboratories, Santa Ana, CA). A maximum of four samples were obtained, and the average value from two measurements with Ͻ10% difference was calculated (26). Pulmonary vascular resistance (PVR) was calculated using the formula [(Ppa Ϫ Pwp)/CO/kg)], and systemic vascular resistance (SVR) was calculated using the formula [(Psa Ϫ Pra)/(CO/kg)].…”