Noninvasive cardiac output monitoring

In an effort to provide high-quality intensive care without increasing morbidity and possibly decreasing mortality, noninvasive means of monitoring hemodynamics have been developed. Recently, commercially available monitoring techniques have been afforded the intensivist for just this purpose. This review will discuss the various means available, their limitations and recent literature describing their clinical use in comparison with pulmonary artery catheterization.

Each method has been tested clinically, some more so than others. The general consensus is that each method correlates well with pulmonary artery catheterization. Each method, however, has limitations. Users must be familiar with the limitations and aware of which method is most appropriate for their patients. In general, the derived data provided by the noninvasive methods parallel those of pulmonary artery catheterization, with the exclusion of some commonly used variables (i.e. mixed venous oxygen, wedge pressure). Some novel variables derived from the new techniques can provide analogous information to that gathered from the pulmonary artery catheter.

In summary, the methods commercially available today to measure hemodynamics in a noninvasive fashion offer good correlation to the traditional data derived from pulmonary artery catheterization. Pulmonary artery catheterization is considered, by most, to be the standard by which to compare other methods and will most likely remain so. This is due to a long history of reliance and clinical familiarity with its use. Additional clinical studies will need to be performed in a heterogeneous population of patients (trauma, burn, sepsis etc.) to enable better determination of reliability and limitations in various clinical scenarios. Overcoming the clinician's personal preference to rely on traditional pressure-derived data will also be a large obstacle to overcome.