Recent developments in cardiac output determination by bioimpedance: comparison with invasive cardiac output and potential cardiovascular applications.

PURPOSE OF REVIEW: To describe recent developments in bioimpedance technique and its application in cardiovascular diseases. Cardiac output determination has been used selectively during recent years because of the need for invasive right heart catheterization. Hence, experience with its application in patients with cardiovascular diseases and especially heart failure is limited. Bioimpedance is a novel noninvasive technique determining changes in instantaneous (during one heartbeat) conductance of a small electrical current transferred through the body. By using different algorithms correcting for various body composition constants, it calculates the change in instantaneous arterial blood volume (that is, stroke volume) and cardiac output. Traditionally, bioimpedance cardiac output is determined using either thoracic or whole body techniques according to the location of the electrodes transmitting and receiving the small electrical current.

RECENT FINDINGS: Significant progress was achieved in recent years in cardiac output determination by bioimpedance. Newer algorithms using thoracic and whole body bioimpedance have demonstrated better correlation with invasive cardiac output determination. In a few preliminary studies bioimpedance-determined cardiac output was found useful in the diagnosis, risk stratification, and treatment titration of some cardiovascular conditions. Further, larger prospective studies are required to determine the true independent value of cardiac output measurement by bioimpedance for the evaluation of cardiovascular diseases and especially heart failure.

SUMMARY: Recently, significant improvement was achieved in cardiac output measurement by bioimpedance with both newer thoracic and whole body techniques. Preliminary studies imply that this measure may be of value in managing some cardiovascular disorders.