The Electrocardiograph: Applications and Limitations—An Analysis of 2000 Incident Reports

Abstract

The first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS) were analysed with respect to the role of the electrocardiograph (ECG). Of these, 138 (7%) were first detected by the ECG. Of the 1256 incidents which occurred in association with general anaesthesia (GA incidents) 48% were “human detected” and 52% “monitor detected”, the ECG was ranked third and detected 121 (19%) of these monitor detected GA incidents. However over 98% of incidents first detected by the ECG were heart rate changes; they would also have been detected by a pulse meter or pulse oximeter which would have supplied additional information about the adequacy of peripheral perfusion. The ECG is a “first-line” monitor in situations with the potential for myocardial ischaemia, complex dysrhythmias or altered myocardial conduction and should be used in all critically ill patients as well as those at significant risk of these problems. The ECG frequently detects incidents involving minor physiological trespass, such as simple heart rate and rhythm changes associated with anaesthetic agents. These incidents are generally detected relatively early in their evolution. AIMS data has confirmed, however, that the ECG has such poor sensitivity for serious physiological changes such as hypoxia, hypercarbia and hypotension that it cannot even be regarded as a useful “back-up” monitor for these problems. Indeed a “normal” ECG in a dangerous situation may lead to a degree of complacency. Because the anaesthetist cannot differentiate between these minor and serious causes of ECG changes, it was decided, for a theoretical analysis, that although the ECG used on its own would have detected 55% of the 1256 GA incidents, had they been allowed to evolve, it could not be assumed that it would do so without potential for organ damage. The ECG may be regarded as an adjunct to, but does not replace, an oxygen analyser, pulse oximeter, capnograph, or high pressure alarm. An ECG should always be available but need not be used for young fit patients unless specifically indicated.