Accuracy of ECG electrode placement by emergency department clinicians

Misplaced ECG electrodes can cause changes in ECG recordings, which could have an impact on clinical decisions. We aimed to determine the inter-rater reliability of ECG electrode placement by senior clinical staff in the ED.

A prospective observational study was conducted in adult patients undergoing an ECG as part of their routine ED care. Adhesive electrodes were left in place after an ECG had been performed by the treating nurse, and subsequently each patient was assessed by two of the three investigators. Each investigator independently recorded the location of the chest electrodes relative to the recommended standard positions. Displacement of the electrodes from the standard positions was measured in the vertical and horizontal planes. The age, sex, weight, height and chest circumference was also recorded. Comparisons were made between investigators to determine variability in assessment of the standard positions.

Measurement of horizontal and vertical displacement for each of the six chest leads in the 77 patients resulted in 924 paired measurements. There was substantial inter-rater variation in the measurement of both vertical (mean 13.5 mm, range 0-105 mm) and horizontal (mean 16.5 mm, range 0-120 mm) displacement. This variation was greater in the lateral chest leads and was more marked in women than in men, especially in the vertical plane (lead V6: men 14.5 mm vs women 27.0 mm, P < 0.01).

Among clinical 'experts', there is wide variation in the identification of the correct location for electrode placement, particularly in the lateral leads and in women. This has significant implications when comparing ECG in which electrodes have been placed by different clinicians.