Accuracy of ECG chest electrode placements by paramedics: an observational study

Background
The use of the 12-lead ECG is common in sophisticated prehospital Emergency Medical Services but its value depends upon accurate placement of the ECG-electrodes. Several studies have shown widespread variation in the placement of chest electrodes by other health professionals but no studies have addressed the accuracy of paramedics. The main objective of this study was to ascertain the accuracy of the chest lead placements by registered paramedics.
Methods
Registered paramedics who attended the Emergency Services Show in Birmingham in September 2018 were invited to participate in this observational study. Participants were asked to place the chest electrodes on a male model in accordance with their current practice. Correct positioning was determined against the Society for Cardiological Science & Technology’s Clinical Guidelines for recording a standard 12-lead electrocardiogram (2017) with a tolerance of 19mm being deemed acceptable based upon previous studies.
Results
52 eligible participants completed the study. Measurement of electrode placement in the vertical and horizontal planes showed a high level of inaccuracy with 3/52 (5.8%) participants able to accurately place all chest electrodes. In leads V1 - V3, the majority of incorrect placements were related to vertical displacement with most participants able to identify the correct horizontal position. In V4, the tendency was to place the electrode too low and to the left of the pre-determined position whilst V5 tended to be below the expected positioning but in the correct horizontal alignment. There was a less defined pattern of error in V6 although vertical displacement was more likely than horizontal displacement.
Conclusions
Our study identified a high level of variation in the placement of chest ECG electrodes which could alter the morphology of the ECG. Correct placement of V1 improved placement of other electrodes. Improved initial and refresher training should focus on identification of landmarks and correct placement of V1.