Asphyxial cardiac arrest, resuscitation and neurological outcome in a Landrace/Large-White swine model

Abstract

The vast majority of laboratory studies on animals have focused on ventricular fibrillation (VF) and not on cardiac arrest (CA) resulting from asphyxia. The aim of this study was to develop a clinically relevant animal model in Landrace/Large-White swine of asphyxial CA resuscitated using the European Resuscitation Council guidelines. Survival and 24 h neurological outcome in terms of functional deficit were also evaluated. Asphyxial arrest was induced by clamping the endotracheal tube (ETT) in 10 Landrace/Large-White piglets. After 4 min of untreated arrest, resuscitation was initiated by unclamping the ETT, 100% oxygen mechanical ventilation, 2 min chest compressions and epinephrine administration. Advanced Life Support algorithm was followed. In case of restoration of spontaneous circulation, the animals were supported for one hour and then observed for 23 h. Coronary perfusion pressure was significantly higher in surviving animals (P , 0.001) during cardiopulmonary resuscitation. End-tidal CO 2 was significantly higher in the animals that survived than in non-surviving animals (P ¼ 0.001). All of the animals were severely neurologically impaired 24 h after CA. This refined model of asphyxia CA is easily reproducible and may be used for pharmacological studies in CA.

Intraarrest Rhythms and Rhythm Conversion in Asphyxial Cardiac Arrest

“…The observed VF frequency (63%) at 4 minutes of ACA is significantly different when compared to the reported frequency of nonasphyxial VF cardiac arrest (≤ 30%; p < 0.001, using exact binomial testing). 12,15 Due to the small number of animals with asystole, statistical comparisons between this group and the other groups were not performed. However, we found a trend between time to cardiac arrest and initial cardiac arrest rhythm; the time to cardiac arrest in animals with asystole (10.87 AE 0.17 minutes) was longer compared to animals with PEA (8.26 AE 1.60 minutes) and VF (7.29 AE 0.67 minutes), with the difference between VF and PEA groups being not statistically significant.…”

“…12,15 When compared to the frequency of nonasphyxial VF cardiac arrest (≤30%), we estimated that 30 animals would be a sufficient sample size to establish the desired increase in VF frequency (from 30% to 60%) with 90% power, at the alpha = 5% significance level, using exact binomial testing. Power analysis was conducted using Power Analysis and Sample Size (PASS, version 13) for Windows.…”

“…Swine have been used successfully as a research model both for VF and for ACA in adults and children. 15,41 Moreover, swine have been used extensively in modeling pediatric cardiac arrest. 15 Therefore, to evaluate cardiac rhythms during ACA, we used the Landrace large white piglets due to their advantages in comparison with other animal models, especially in cardiac electrophysiology, coronary artery anatomy, and respiratory function, which closely resemble those of humans.…”

“…15 In brief, after premedication of each animal with intramuscular injection of 0.5 mg/kg midazolam, 10 mg/kg ketamine hydrochloride, and 0.05 mg/kg atropine sulfate, the auricular vein was cannulated, and anesthesia was induced, with 2 mg/kg 1% propofol and 2 lg/kg fentanyl. The animal was intubated using an endotracheal tube with a cuff (Portex, 5 mm ID, Smiths Medical, St. Paul, MN) and was immobilized in the supine position on a surgical table.…”

“…[9][10][11][12][13][14][15][16] Recent evidence suggests that ventricular fibrillation (VF) is more common than was originally believed in the setting of out-of-hospital asphyxial cardiac arrest (ACA), 11 while it is becoming a more frequent presenting arrest rhythm to emergency departments. 12,13 Moreover, the incidence of VF in pediatric cardiac arrest varies between 4 and 23%.…”