Cardiac output using the saline-dilution impedance technique.

The author discusses the basis for the indicator-dilution method and illustrates the use of saline to measure cardiac output accurately, along with the technique of electrical calibration of the dilution curve. He considers various indicators, showing why saline is the best for cardiac output measurements. He shows how to calibrate electrically the saline-dilution curve, and he describes two types of electrodes used to measure the curve. He cites the results of some verification studies, concluding that the advent of a catheter-tip, terapolar electrode array placed in the pulmonary artery and injection of the saline indicator into the right atrium using the same catheter, along with the electrical calibration technique, makes the saline-indicator method a serious contender for clinical use because of its high accuracy and low cost.