Read more: How To Use AED: The Ultimate Guide
It can be difficult to treat people who are in ventricular fibrillation. Some patients will continue to experience refractory ventricular fibrillation despite valiant efforts, such as the performance of high-quality chest compressions with few breaks, the implantation of advanced airways, numerous standard defibrillation (AED) attempts, and other interventions for advanced cardiac life support. Unfortunately, this leaves a significant vacuum in care, leaving emergency care workers with few therapeutic alternatives and a declining chance of successful resuscitation as more defibrillation efforts are made.
In the context of refractory ventricular fibrillation, modified defibrillation techniques have recently been proposed.
Two different ways were proposed:
Double sequential external defibrillation (DSED): two defibrillators deliver rapid sequential shocks that are spaced by less than one second.
ector-change (VC) defibrillation: the placement of the pads is changed from anterior-lateral to anterior-posterior positions.
Studies on these tactics have produced encouraging preliminary findings.
Another study from NEJM has just published the findings of a sizable, multiagency, cluster-randomized trial with crossover that took place in Ontario, Canada. They compared the effectiveness of DSED and VC defibrillation to standard defibrillation in adult patients with refractory ventricular fibrillation of suspected cardiac origin.
According to advanced cardiac life support guidelines, patients who were still in ventricular fibrillation after three defibrillation attempts were divided into one of three groups based on the defibrillation strategy that the responding emergency medical service had been randomly assigned at the time.
The main result was making it out of the hospital alive. Secondary results included ventricular fibrillation ceasing, spontaneous circulation returning, and a positive neurologic outcome at hospital release.
Result
The trial was terminated early with a total of 136 patients assigned to normal defibrillation, 144 to VC defibrillation, and 125 to DSED. While there were notable discrepancies between the VC and traditional defibrillation groups, the patient characteristics in the three groups were essentially similar. Age, sex, and the receipt of bystander cardiopulmonary resuscitation were taken into account as multivariable analyses were used to correct for imbalances.
In the analysis of survival to hospital discharge, DSED was associated with higher survival than standard defibrillation (30.4% vs. 13.3%; relative risk, 2.21; 95% confidence interval [CI], 1.33 to 3.67); VC defibrillation was also associated with higher survival (21.7%; relative risk [ Additionally, DSED was linked to a higher rate of survival with normal neurologic function compared to standard defibrillation (relative risk, 2.21; 95% confidence interval, 1.26 to 3.88), but VC defibrillation did not seem to offer a comparable benefit (relative risk, 1.48; 95% confidence interval, 0.81 to 2.71).
Restrictions
The trial’s findings are promising, but there are a few restrictions. First of all, the postresuscitation treatment, such as performing targeted temperature management or percutaneous coronary intervention, is not discussed by the authors, which could seriously complicate the relationships found in this experiment. We wouldn’t be able to discern the independent impact of the various defibrillation procedures if there were between-group variations in how well these or other interventions were carried out.
The confidence intervals for the relative risk estimates overlapped, making it impossible to determine if one technique would be better than the other even though DSED appeared to be associated with a higher benefit than VC defibrillation. The implementation of the more complicated DSED defibrillation method presents practical difficulties due to the requirement for additional equipment, additional training, and additional experience from emergency personnel. This method requires two defibrillators with different pad locations that must be activated sequentially but quickly. Additionally, there is a potential possibility that DSED errors could harm defibrillators or worsen cardiac rhythm.
The use of DSED and VC defibrillation for refractory ventricular fibrillation is supported by this trial’s addition of crucial new effectiveness data from a multiagency prehospital clinical trial. This experiment represents a significant advancement in our understanding of the efficacy of various treatment modalities given the difficulties in conducting high-quality prehospital resuscitation studies. However, more investigation is required to clarify the effects of DSED and VC defibrillation for refractory ventricular fibrillation.
This investigation should include trials that are particularly designed to compare the two methods and those that take postresuscitation care into account. Such prolonged forms of defibrillation are not yet ready for routine therapy, but they may be taken into consideration if all other forms of treatment have failed.