The potential mechanism of the detrimental effect of defibrillation prior to cardiopulmonary resuscitation in prolonged cardiac arrest model

초록

Defibrillation is no longer universally recommended as initial intervention for the reversal of ventricularfibrillation (VF) after a prolonged and untreated cardiac arrest. We sought to examine this issue in ananimal model where a prolonged untreated VF was induced. The aim of this study was to investigate thepotential mechanism of the detrimental effect of defibrillation prior to cardiopulmonary resuscitation(CPR) in prolonged cardiac arrest model. VF was electrically induced in 32 domestic male swine weighing40±3 kg and remained untreated for 15 minutes. The animals were then randomly allocated to either theinitial defibrillation group or the chest compression group. Mean aortic pressure, right atrial pressure andcoronary perfusion pressure (CPP) were continuously measured during the performance. The dimensionsof the left ventricle (LV) were assessed by echocardiographic methods. The CPP induced by CPR afterdefibrillation was significantly lower in the initial defibrillation group than in the chest compressiongroup; 1 minute after defibrillation (9±3 mmHg vs. 14.8±7 mmHg (P<0.05)), and after 5 minutes 16±5mmHg vs. 21.7±1 mmHg (P<0.05). The LV volumes were reduced from 18±2 mmHg to 14±1 mmHgafter defibrillation (P<0.05). In brief, this study showed that the conducting defibrillation prior to chestcompression may cause a contracture of the LV, resulting in lowering CPP, thus dropping the efficiency ofchest compression in a prolonged cardiac arrest model.

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