Patent ID: 6858013

Claim:
A method for determining a cardiac output of a patient, wherein the patient's respiration cycle is determined and an indicator is injected into the patient's bloodstream over a period of substantially one respiration cycle and an injected amount of indicator is established, wherein a change in an indicator value in the bloodstream downstream of the injection point is integrated over a measurement period (T 1 ) of a number (n) of respiration cycles, first variation in the indicator value is integrated over substantially a period (T 2 ) of one respiration cycle, prior to the injection, and a second variation in the indicator value is integrated over a period (T 3 ) of substantially one respiration cycle after the measurement period (T 1 ), wherein an average of the first and the second integrated variations is determined, and wherein the change in the indicator value caused by the injection is determined on the basis of a difference between the change in the indicator value integrated over said measurement period (T 1 ) and n times the average of the integrated first and second variations, wherein the cardiac output is determined on the basis of the thus determined change in the indicator value, an amount of indicator injected into the blood and an initial value thereof.