Noninvasive cardiac monitoring.

During the past few years a number of technological developments have made new methods of noninvasive cardiac monitoring available for use in the intensive care unit. Some of these can be used almost continuously some repeatedly, but intermittently, to manage critically ill patients. In addition to avoiding the risks of pain, bleeding, and infection associated more with invasive studies, a major advantage of many noninvasive studies is that one is able to conduct them at the bedside. Echocardiography has been most useful in this regard, but now even nuclear imaging can be carried out with commercially available portable scanners. Doppler techniques, formerly understood only by those with considerable background in cardiology have now evolved to provide the clinician with a simple method of measuring cardiac output. ECG monitoring too has undergone recent refinements to automate the detection of ST segment changes that escape routine observation of the bedside monitor.