Method and apparatus for estimating the reliability of cardiac output measurements

An apparatus for estimating a reliability of cardiac output;

• (CO);
• measurements for a subject obtained using an arterial waveform analysis;
• (AWA);
• technique, wherein the AWA technique is calibrated using CO measurements obtained using a thermodilution CO measurement technique, the apparatus comprising a processor configured to:
• (a) during a first time period in which the AWA technique is calibrated using a first CO measurement obtained using the thermodilution CO measurement technique:
• (i) initiate inflation of a cuff that is at a first location on the subject;
• (ii) obtain a first cuff pressure signal comprising measurements of pressure inside the cuff during inflation;
• (iii) analyse the first cuff pressure signal to derive a relationship between oscillations in arterial volume beneath the cuff and pressure in arteries;
• and
• (iv) estimate a first arterial compliance of the arteries for a range of cuff pressures based on the determined relationship;
• (b) during a second time period that is after the first time period, repeat functions (i)-(iv) to estimate a second arterial compliance of the arteries;
• and
• (c) use a result of a comparison of the first arterial compliance and the second arterial compliance to determine a reliability of CO measurements obtained using the AWA technique during the second time period.