Cardiac Output Estimation from Arterial Blood Pressure Waveforms

Cardiac output (CO), defined as the volume of blood pumped by the heart per unit time (often expressed in liters per minute), is the critical variable characterizing circulatory function, but it is also one of the most difficult to measure. Thermodilution cardiac output (TCO) is generally regarded as the "gold standard" among CO measurements. By introducing a small amount of cool fluid into the blood upstream of the heart, and observing how rapidly the blood temperature equilibrates, the flow and thus the CO can be calculated. TCO is highly invasive, intermittent, difficult to perform, and has sufficient potential to cause complications that it is used only when an accurate CO measurement is essential -- and even then, TCO errors are on the order of 15 to 20%.

For over a century, many researchers have proposed alternative, minimally invasive or non-invasive methods of estimating CO, based on features of the arterial blood pressure waveform. The current study rigorously compares 11 of these estimates against TCO using 120 subjects from the MIMIC II database (all subjects for whom multiple TCO measurements were recorded at the time of the study).

The code directory contains Matlab implementations of the CO estimation algorithms, together with additional Matlab code to provide a set of tools for exploring CO estimators. The data directory contains a list of the original MIMIC II records used in this study.