Inappropriate Public Access Defibrillation
The use of automated external defibrillators (AEDs) holds the promise of an increase in the number of survivors of out-of-hospital cardiac arrest. One of the basic tenets behind this strategy is the claim that lay people can use an AED. This is dependent on the performance of a critical rhythm analysis algorithm that interprets the ECG. Currently used algorithms claim a specificity of 100% for all shockable rhythms. However, surveillance for inappropriate shock decisions and improvement of analytical algorithms by AEDs are necessary to provide appropriate resuscitation by first responders. A 75-year-old man collapsed in a public place. Emergency personnel with the aid of an AED successfully resuscitated him. Analysis of the initial rhythm by the AED correctly identified ventricular fibrillation (VF), and a shock was delivered appropriately and successfully (Figure, A). After this, P waves could be observed during the second analysis (Figure, B) and were clearer soon afterward (Figure, C and D). The algorithm also analyzed this rhythm to be VF and advised a shock. Panel B of the Figure demonstrates medium-frequency artifacts of 0.1 to 1 mV in amplitude of unknown origin, causing an inappropriate AED shock. This inappropriate decision highlights the need for registries to be maintained of AED discharges so that AED detection algorithms can be refined to achieve higher specificity. Cardiac life support training should also continue to be given to potential AED users, along with a visual display of rhythm and capacity, to manually override the AED decision to prevent inappropriate shocks.