Intrinsic cardiac output variability in the anesthetized normal and splenectomized dog

¹ Surgical Research Laboratory, Los Angeles County Hospital, Loma Linda University School of Medicine, Los Angeles, California

In an effort to determine variations in the normal hemodynamics of the dog, serial cardiac output and blood pressure measurements were made and peripheral resistance values calculated in the same animal over a prolonged period of time. The hemodynamic effect of splenectomy was observed by comparing seven lightly anesthetized normal dogs with seven splenectomized animals. The standard deviation for serial cardiac output values in individual normal dogs was ±6–15%. The mean value for the standard deviation in the entire group was ± 10.5%. The standard deviation for the cardiac output values in splenectomized dogs varied from ±6.5 to 29.5%. The mean value for the standard deviation in this group was ± 15%. Although the normal dogs appeared to have a more stable cardiac output, statistical evaluation of the data showed no significant difference in cardiac output variation between normal and splenectomized dogs. The intrinsic variation in the cardiac output of the dog is apparently physiological in origin and must be considered in interpreting serial observations of cardiac function.