Poor clinical outcomes occur in patients with refractory Ventricular Fibrillation (VF), which is defined as persistent VF following three consecutive defibrillation attemps and standard Advanced Life Support (ALS) treatment.
Double sequential defibrillation and vector change defibrillation, have been identified as showing superior outcomes to standard defibrillation (1).
In managing VF we need to differentiate between:
- Shock Refractory VFÂ (5-20%) which is continuous VF before and after each shock and
- Recurrent VF: (> 50%)Whixh is the absence of VF for >Â 5 sec after any shock, followed by refibrillation
Patients with recurrent VF have a higher rate of survival, however it is sometimes difficult to ascertain which type of VF we have, as it can occur during the time that CPR is recommenced.
The Study
Magliocca A, et al. Amplitude spectrum area to predict true shock-refractory ventricular fibrillation during out-ofhospital cardiac arrest. Resuscitation 2025. https://doi.org/10.1016/j. resuscitation.2025.110695.
The objective of this study was to determine if pre-shock AMSA could identify cases of  shock-refractory VF and refractory-recurrent VF in a large database of OHCAs with shockable rhythm.
The authors’ conclusion was:
“This study reveals AMSA as a promising predictor for differentiating true shock-refractory VF from refractory-recurrent VF in OHCA.”
Read the whole review and the discussion of the limitations and promising elements of this study here at EM Mastery.
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References
- Cheskes S, et al. Defibrillation strategies for Refractory Ventricular Fibrillation. N Engl J Med 2022;387:1947–56.
- Meessen JMTA, et al. High amplitude spectrum area measured in real-time during cardiopulmonary resuscitation is associated with favourable long-term neurological outcome after out-of-hospital cardiac arrest. J Clin Anesth 2024;93:111323.
- Ruggeri L, et al. Amplitude spectrum area measured in real-time during cardiopulmonary resuscitation – how does this technology work?. Resuscitation 2023;191:109941.
