Continuous CO measurement by EB is a highly technical issue requiring expert opinion for evaluation. At present, the NIH, American Society of Anesthesiologists, and the American College of Cardiology consider continuous CO monitoring by EB to be investigational. However, EB has numerous advantages when compared with other presently available techniques. Consequently, advances may require that the OHTA conduct another assessment in the near future. The NIH suggested that the use of EB on a noncontinuous basis in selected patients to measure changes in CO (but not the absolute value of CO) is reasonable. If the use of EB on a continuous basis is contemplated, then studies should be conducted to determine the safety of long-term electrical input into the thorax. Electrical bioimpedance should not be used in patients with pacemakers and may be inappropriate in patients with regurgitant valvular heart disease, intracardiac shunts, arrhythmias, ventricular asynchrony, tachycardia, hypertension, significant airway obstruction, or in patients undergoing therapy such as atropinization, all of which may change the shape of the dZ/dt waveform.