Very small microspheres are useful for the determination of cardiac output but not organ blood flow in conscious rabbits

Summary Very small microspheres with a diameter of 8–10 m can be used for the measurement of cardiac output, by the reference flow method, in conscious rabbits. However, they were found not to be suitable for the determination of the distribution of cardiac output or blood flow to most organs. These small microspheres offer certain advantages for the measurement of cardiac output; the numbers required to achieve a specified accuracy of measurement are discussed.