Cardiac Output

Cardiac Output is traditionally measured in one of two ways. In acute studies the Transonic Transit-Time Flowmeter fitted with a cardiac output probe is the preferred method as it provides a continuous signal. Where minimally invasive procedures are required, Cardiac Output by thermo-dilution is the standard method.

For details of the Transonic continuous CO measurement, please click here.

Cardiac Output by Thermodilution.

For the thermodilution method, we recommend the excellent Cardiotherm 500 series of Cardiac Output monitors. These are well made, easy to use and provide consistent, reliable measurements.

A bolus of either room temperature (or iced) saline or glucose is injected into the right-side of the heart. The resulting change in temperature is sensed in the pulmonary artery (or in the aorta in small subjects). The passage of mixed blood/indicator by the measurement site creates a dilution curve representing the change in temperature. The area bound by the curve is inversely proportional to the volume of blood passing the detection site. The Cardiotherm 500 uses this information to calculate cardiac output formatted in either litres or millilitres per minute.

The Cardiotherm 500 uses either standard thermistor based catheters or the optional 'Microprobe' sensor for use with small subjects.

The Cardiotherm comes with analogue outputs to allow external recording.