CPR - Placement of Electrodes

Background Info

As reported by the American Heart Association (AHA), sudden cardiac arrest is not a rare event ( Heart Disease and Stroke Statistics - 2018 Update ). Every year, approximately 356,000 people suffer from out-of-hospital cardiac arrest (OHCA) in the USA. It is well recognized that widespread training programs are required to improve the rate of bystander CPR. Many states in the U.S. therefore encourage CPR training as early as on a middle school level ( Addressing Gaps in Cardiopulmonary Resuscitation Education ). The AHA emphasized that immediate high quality CPR and early defibrillation are most important links of the chain of survival .

Most recently, a group of investigators from the Research Center for Emergency Medicine, Aarhus University Hospital, Denmark (see references below) reported suboptimal instructions and training with regard to the correct placement of self-adhesive defibrillation pads.

The Effect of Pad Placement on Defibrillation Success

The body of scientific literature investigating the effect of pad placement on defibrillation success is small. In 2016, one experimental study in pigs compared three different positions of defibrillation pads. The study was partially supported by a grant from Physio-Control. Small variations in pad placement had a significant effect on the efficacy of the defibrillation shock. ( Esibov et al. 2016 ) The adjacent positions of the pads were less than three centimeters (about 1.2 inches) apart. It has been reported that pad placement can vary up to 2 inches (5 cm) among laypersons and staff of the emergency medical services (EMS). The investigators confirmed that the position of the defibrillation electrodes was very important with regards to defibrillation success. However, they concluded that it was impractical to achieve optimal pad placement in real-world situations considering the high level of stress of rescuers and different shapes and body sizes of the victims of cardiac arrest. Instead, they suggested to apply the optimal defibrillation waveform and shock dose.

Correct Placement of AED Adhesive Pads

Most recently, Henrik Bødtker and colleagues from Denmark investigated systematically the correct placement of self-adhesive defibrillation electrodes by laypersons. They found that only 30% of the laypersons were able to correctly attach the AED electrodes. Most often, the left apical electrode was placed in an anterior position instead of the correct left lateral position. As pointed out above, incorrect placement of defibrillation electrodes has the potential to reduce the chance of successful defibrillation and therefore chance of survival.

Based on previous publications by Nurmi et al. (2005 ), Bødtker and Rosendahl reviewed instructional material located on the websites of six major manufacturers (Physio-Control, Cardiac Science, Phillips, Heartsine, Defibtech and Zoll). They found that all pictorial guides provided by AED manufacturers showed the left electrode in an anterior view instead of a lateral view. In addition, the investigators demonstrated that only two out of six product videos depicted the correct left lateral position of the electrode (Physio-Control, Cardiac Science). Finally, out of 16 different types of defibrillation electrodes only three labels printed on the pad showed the correct position of the left lateral electrode. The authors concluded that there was an urgent need for further research on the correct placement of AED electrodes.

References
1. Bødtker, H. and D. Rosendahl (2018). "Automated external defibrillators and defibrillation electrodes from major manufactures depict placement of the left apical defibrillation electrode poorly!" Resuscitation 125: e11-e12.
2. Bødtker, H. and D. Rosendahl (2018). "Correct AED electrode placement is rarely achieved by laypersons when attaching AED electrodes to a human thorax." Resuscitation 127: e12-e13.


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Improved Methods of Illustrating the Correct Pad Placement

Several authors have suggested to use a lateral view to depict the correct position of the defibrillation pads (pictures are not shown due to copyright):
1) Nurmi et al. 2005. Layperson positioning of defibrillation electrodes guided by pictorial instructions.Resuscitation 64, 2: 177-180
2) Bødtker et al. 2017. Abstract 20478. A Novel AED Electrode Design Significantly Improves Laypersons Abilities to Correctly Place AED Electrodes. Circulation 136, Suppl 1, p A20478

The European Resuscitation Council Guidelines for Resuscitation 2015 uses a lateral view in the 2015 guidelines:
European Resuscitation Council Guidelines for Resuscitation 2015 - AED Electrodes

 

Summary

In summary, current research shows that misplacement of the left apical defibrillation electrode is common among laypersons and emergency staff. Bødtker et al. found that pictorial guides and other instructional material provided by AED manufacturers does not seem to adhere to most recent guideline recommendations.

It is suggested that AED training programs, pictorial guides, printed on AED devices and on defibrillation pads, should depict a left-lateral view of the body to emphasize the correct placement of the left apicolateral AED electrode. In addition, voice prompts given by AED devices should provide easy to understand instructions on where to correctly place the defibrillation pads. This will help to improve defibrillation success and improve outcome.