First time use of manual pressure augmentation for ventricular fibrillation arrest in the community

A 47 year-old man was found unresponsive after falling off his bicycle at low speed in a rural area. Bystander cardiopulmonary resuscitation (CPR) was performed for 10 minutes until an Automated External Defibrillator (AED) from a nearby football oval arrived. Three shocks restored sinus rhythm and the patient was fully conscious when the ambulance arrived. The patient then had 3 further shocks for ventricular fibrillation (VF) over the next 45 minutes. All three shocks were successfully defibrillated with 200 J, however on the final shock manual pressure augmentation (MPA) was performed at the time of defibrillation. MPA involves an operator wearing gloves pushing down on the sternal and apical patches at the time of energy delivery using either a clenched fist or open palm (Fig. 1). Data from the ZOLL® X Series® Defibrillator (Zoll Medical, Massachusetts, USA) which employs a rectilinear biphasic waveform demonstrated an 18% reduction in transthoracic impedance (TTI) for the MPA shock: shock 1 59 Ω, shock 2 60 Ω, shock 3 with MPA 49 Ω. No perceptible current was felt by paramedics. ECG at the scene demonstrated inferior ST-elevation and given his remote location he received intravenous thrombolysis at the scene. Coronary angiogram upon arrival to hospital demonstrated an 80% right coronary artery stenosis for which he underwent stenting. Left ventricular systolic function was normal and he was discharged home on day 3 without any neurological sequelae.

Numerous studies have recently reported on improved success rates for cardioversion of atrial fibrillation with application of additional pressure to the chest wall, either with paddles or manual pressure. Our group performed the multi-centre Cardioversion-BMI randomized trial of 125 obese patients(1) and found that application of extra pressure in the form of paddles was superior to standard adhesive patches at 200 J. However, in those who failed both pads and paddles, MPA was able to safely successfully cardiovert 16/20 patients without safety issues for operator or patient. Ramirez et al. reported similar findings whereby pressure over patches was applied using disconnected handheld paddles and resulted in a 7.4% increase in cardioversion success. More recently, a randomized trial comparing standard cardioversion with active compression of the anterior electrode in AF found higher cardioversion success with the latter technique (96% vs 84%; p = 0.0455).

This is the first report of MPA use for defibrillation of ventricular arrhythmias. We postulate that in addition to reducing transthoracic impedance, this technique may improve emptying of the lungs, while shortening the distance between electrodes and ventricles and ultimately resulting in improved delivery of current to the heart (this cannot be measured). Additional potential benefits for ventricular arrhythmias include reduced interruption of cardiopulmonary resuscitation by maintaining continuous chest compressions until energy delivery and maintaintenance of an intra-thoracic to extra-thoracic pressure gradient. As such, we are commencing the AUGMENT-VA randomised controlled trial comparing standard care with addition of MPA in patients with out of hospital arrest due to shockable rhythms (ACTRN12621000804886).