The false negative phenomenon: importance and causes in the “Girona territori cardioprotegit” project. A retrospective observational study

Abstract

BACKGROUND AND AIMS: Out of hospital cardiac arrest is a first order health problem, public defibrillation programs have accomplished to reduce mortality and neurologic consequences, thanks to CPR training and the use of automated external defibrillators (AED). However, it has been identified that these devices can present false negatives (FN) in field conditions, not treating cardiac arrythmias that are potentially reversible. The main objective of this end of degree project is to know the incidence of false negatives in the “Girona Territori Cardioprotegit” project and to analyze its features. METHODS: Retrospective analysis of the prospective AED tracings register from the beginning of the “Girona Territori Cardioprotegit” program until today (2011-2023). The tracings were analyzed by experts (Gold Standard) and were classified in shockable rhythms or non-shockable rhythms, to identify FN. Incorrect uses or tracings where the information was incomplete were excluded from the analysis. RESULTS: During the study (830) AED activations were registered, from them (689) were considered to analyze: (527) were considered by the AED as shockable. (39) FN were identified (Global FNR of 5.6%). In the FN we discovered that (69%) were fine VF (<200mcv) and in (5) cases, CPR maneuvers interfered with the device’s algorithm. No differences in the % of FN between mobile and fixed AEDs were identified, nor was there a temporal trend in this phenomenon. From (39) patients, (11) were transferred to the hospital. CONCLUSIONS: The AEDs in the “GTC” project have excellent diagnostic precision (93.61%) with moderate sensitivity (81%) and excellent specificity (98%). The number of false negatives is still low and consistent with preliminary research. FN were mostly caused by non-identification of fine VF. It was also detected that patients with FN have a lower chance of survival compared to patients with shockable rhythms that were treated by the devices