Straight from the Heart: Understanding Cardiac Output Monitoring Techniques

Cardiac output—the amount of blood pumped by the heart per minute—is a core vital sign that indicates circulatory well-being. The traditional approach to monitoring cardiac output is pulmonary artery catheterization using thermodilution as the measurement method. But this invasive procedure is associated with a number of complications, including pulmonary artery rupture. In addition, there is a lack of evidence regarding the efficacy of the technique in improving clinical outcomes. As a result, though it is still the most common method, this technique is being used in a small and declining percentage of critical care patients.

The drawbacks of pulmonary artery catheterization have spurred a search for less invasive alternatives for monitoring cardiac output. As a result, the market has seen a surge of minimally invasive and noninvasive cardiac output monitors in recent years. Each vendor claims that its technique is the best alternative to pulmonary artery catheterization for hemodynamic management of patients using cardiac output measurements.

We’ve taken a look at the current marketplace. Based on our review of published literature, we believe that all the alternative techniques have some limitations; however, they all may still be useful under certain clinical conditions. In the sections that follow, we describe these techniques and the devices that use them.

​Table: Summary of Findings: Cardiac Output Monitors