Systematic review of swine models for ventricular fibrillation induction in evaluating cardiopulmonary resuscitation methods

Abstract

Background and purpose: Ventricular fibrillation (VF) has been studied using a variety of swine models, historically balloon occlusion of the coronary artery and asphyxiation, and more recently, percutaneous electrical induction. These methods differ in face and construct validity, as well as requirement for expertise, cost, and duration. This study aimed to provide a systematic review these methods and their selection in research. Methods: Electronic searches were conducted in PubMed, Scopus, and Google Scholar. The Utstein-Style Guidelines for Uniform Reporting of Laboratory cardiopulmonary resuscitation (CPR) research were used to identify the extracted variables by two independent investigators. Discrepancy was resolved by discussion with the third investigator. Results: We included 236 studies published from 1990 to 2024. The most commonly used method was electrical induction using a pacing wire cannulated through the external jugular vein into the right ventricle (n = 112), followed by transthoracic electrical induction (n = 28), asphyxiation (n = 20), electrical induction via two subcutaneous needles (n = 15), and balloon occlusion (n = 10). The mean and standard deviation (SD) of the untreated VF duration were 6.9 and 5.0 minutes, respectively. Female and male pigs were used exclusively in 52 and 45 studies, respectively; both sexes were used in 31 studies; 106 studies not reporting the sex. The mean weight of the pigs was 30.2 ± 12.4 kg in 209 studies, and the number of pigs used in the studies ranged from 2 to 271 with a median of 20 (interquartile range: 15–30) pigs in 223 studies. The four most commonly used drugs for anesthesia/preparation were ketamine (n = 145), propofol (n = 76), isoflurane (n = 68), and pentobarbital (n = 61), either alone or in combination. Higher current and voltage were used for less invasive methods. Conclusions: The two most common electric method to induce VF were invasive pacing at the right ventricle and non-invasive transthoracic electrical induction. Asphyxiation was the most common ischemic VF induction. The choice of the VF induction method depends on cost, expertise, feasibility, and the nature of the CPR intervention to be tested.