Efficacy of 2 strategies to detect body position ST-segment changes during continuous 12-lead electrocardiographic monitoring.

Body positional change is the most frequent cause of false positive ST-segment monitor alarms. This study evaluates 2 strategies to distinguish ST events due to positional change from those due to transient myocardial ischemia: 1) A biosensor device to indicate body position with tick marks on the electrocardiogram (ECG) tracing, and 2) An initially recorded ECG "template" in four positions (supine, right, left, and upright) for subsequent comparison with ST alarm ECGs. A purposive sample of 96 patients on a cardiac telemetry unit was recruited to have both strategies implemented and evaluated. The biosensor correctly identified all 4 body positions in the 96 patients. A subgroup of 30 patients were continuously monitored and 9 (30%) had at least 1 ST event due to body position change, for a total of 25 false positive events. Of the 25 positional events detected by the biosensor, the ECG template method detected 18 (73%). The biosensor method is superior to the ECG template method for detecting positional ST events. However, a limitation of both strategies is that they require clinicians to be skilled in integrating such positional information to reach a correct diagnosis.