[Effect of burns on cardiac performance in the dog]

Changes in cardiac performance after a third-degree 50% burn were studied using seventeen mongrel dogs divided into three groups: A, sham burn (n = 6); B, burn (n = 5); C, burn + fluid therapy (n = 6). From the measurements of local ventricular dimension and left ventricular pressure (P), end-systolic pressure-length ratio (Emax) mean velocity of circumferential fiber shortening (mean Vcf), peak dp/dt, and percent shortening (% delta L) as indices of myocardial contractility were calculated. Cardiac output (CO), aortic pressure (Aop) and heart rate (HR) were also measured. All measurements were repeated every 30 minutes until 360 minutes after burning. In group B and C, CO as well as left ventricular end-diastolic pressure (LVEDP) and length (EDL) as indices of the preload were significantly decreased as compared with group A. All indices of myocardial contractility in B and C were significantly lower than those in A. These results indicate that, in severe thermal burns, cardiac pump function is depressed by the fall of myocardial contractility in addition to the decrease in the preload.