The monitoring of the cardiac output (CO [l/min]) is
usually carried using various dilution methods.
The one most commonly used in clinical routine is thermodilution
thanks to its relatively easy application and repeatability.
Unfortunately this method is unsuitable in instable haemodynamic,
extremely hyperdynamic, or hypodynamic conditions as is normally the
case in a critical patient.
It is therefore precisely in these clinical sectors where the CO
monitoring is so vital that thermodilution is liable to give rise
to problems for technical reasons or due to the theory of the method
(necessity of a stable flow, etc).
It often happens that apart from not providing CO values linked to
the rapid haemodynamic variations (pathological and/or
pharmacological), it may also create discomfort for the patient as a
result of the high invasiveness required.
The continuous, beat-to-beat monitoring of the CO may represent an
extremely useful parameter for assessing the heart conditions, and
therefore play a fundamental role in diagnostics and clinical
This explains why such a great number of methods have been applied,
especially over recent years.