Changes in left ventricular preload and contractility following severe burns in the dog

To examine the effects of severe burns on preload and left ventricular (LV) contractility, we continuously measured LV pressures and dimensions in severely burned dogs throughout the early part of the postburn period. Hemodynamic parameters, including cardiac output (CO), mean aortic pressure (MAP), heart rate (HR), LV pressures and their first derivatives (dP/dt), and the LV regional dimension, were measured and compared before and every 30 min after burns were produced (up to 360 min) in four groups: group A (n = 7), dogs with sham burns; group B (n = 5), dogs with nonresuscitated full-thickness burns involving 50% of the total body surface area; group C (n = 6), dogs with burns resuscitated with lactated Ringer's solution at 4 ml X kg X % burn/24 h; and group D (n = 6), dogs with burns resuscitated with 1.5% dextran in lactated Ringer's solution at 2 ml X kg X % burn/24 h. From these measurements, we obtained the LV end-diastolic segment length (EDL) as an index of preload and three indices of cardiac contractility, i.e., peak dP/dt, the percentage of shortening (% delta L), and mean Vcf. Our results showed that CO, MAP, and preload (i.e., EDL) decreased significantly more in the three burn groups (groups B, C, and D) than in the sham burn group, but that there were no significant differences in CO, MAP, and EDL among the three burn groups. The three indices of contractility also decreased significantly more in the three burn groups than in the sham burn group.(ABSTRACT TRUNCATED AT 250 WORDS)