Comparison between two methods for cardiac output measurement in propofol-anesthetized dogs: thermodilution and Doppler.

摘要

Objective: To compare cardiac output (CO) measured by Doppler echocardiography and thermodilution techniques in spontaneously breathing dogs during continuous infusion of propofol. To do so, CO was obtained using the thermodilution method (CO_TD) and Doppler evaluation of pulmonary flow (CO_DP) and aortic flow (CO_DA). Study design: Prospective cohort study. Animals: Eight adult dogs weighing 8.3+or-2.0 kg. Methods: Propofol was used for induction (7.5+or-1.9 mg kg-1 IV) followed by a continuous rate infusion at 0.7 mg kg-1 minute-1. The animals were positioned in left lateral recumbency on an echocardiography table that allowed for positioning of the transducer at the 3rd and 5th intercostal spaces of the left hemithorax for Doppler evaluation of pulmonary and aortic valves, respectively. CO_DP and CO_DA were calculated from pulmonary and aortic velocity spectra, respectively. A pulmonary artery catheter was inserted via the jugular vein and positioned inside the lumen of the pulmonary artery in order to evaluate CO_TD. The first measurement of CO_TD, CO_DP and CO_DA was performed 30 minutes after beginning continuous infusion (T0) and then at 15-minute intervals (T15, T30, T45 and T60). Numeric data were submitted to two-way ANOVA for repeated measurements, Pearson's correlation coefficient and Bland & Altman analysis. Data are presented as mean+or-SD. Results: At T0, CO_TD was lower than CO_DA. CO_DA was higher than CO_TD and CO_DP at T30, T45 and T60. The difference between the CO_TD and CO_DP, when all data were included, was -0.04+or-0.22 L minute-1 and Pearson's correlation coefficient (r) was 0.86. The difference between the CO_TD and CO_DA was -0.87+or-0.54 L minute-1 and r=0.69. For CO_TD and CO_DP, the difference was -0.82+or-0.59 L minute-1 and r=0.61. Conclusion: Doppler evaluation of pulmonary flow was a clinically acceptable method for assessing the CO in propofol-anesthetized dogs.