Alternatives to Swan-Ganz cardiac output monitoring

When we are concerned about the adequacy of peripheral oxygen delivery, our monitoring efforts focus on cardiac output as the component easiest to manipulate. Thermodilution is the current method of determining cardiac output because of logistic convenience, but by no means should it be considered the gold standard. Thoracic electrical bioimpedance is an appealing alternative because of its simplicity, noninvasiveness, and ability to track physiologic trends, but there have been a number of warnings against relying on it exclusively, at least until it is further developed. Doppler ultrasound appears to be a valid method in skilled hands, but its accuracy in quantitating cardiac output, especially in the critically ill, remains questionable. Mixed venous oximetry and transcutaneous oxygen monitoring are promising but are still being evaluated.