[Abbr. of c(ardiac) o(utput), as measured by the t(hermo)d(ilution) of blood]
An invasive method of measuring cardiac output that relies on the advancement of a catheter through central veins into the right ventricle.

PATIENT CARE
A cool or room temperature tracer is injected, and the thermal decay (or heating of the blood followed by thermal decay) is used to determine the cardiac output.