Post-resuscitation lung injury of anoxia-induced and ventricular fibrillation induced cardiac arrest in porcine model : a control study

Objective To study the difference in post-resuscitation lung injury between cardiac arrest induced by anoxia and ventricular fibrillation in porcine model. Methods WuZhiShan inbred miniature pigs were randomly(random number) divided into the asphyxia (AS, n=24) and ventricular fibrillation group (VF, n=24). Cardiac arrest (CA) was induced by endotracheal tube clamping or programmed electric stimulation. Cardiopulmonary resuscitation (CPR) or defibrillation was performed for returning of spontaneous circulation (ROSC). Pulmonary perfusion/ventilation measured with isotope scanand positron emission tomography-computed tomography (PET-CT) scanning were done before and 4hrs after ROSC. The oxygenation index (OI), respiratory index (RI), oxygen delivery (DO2), blood lactic acid, and dynamic pulmonary compliance (Cdyn), airway resistance (Raw), extra-vascular lung water index (EVLWI), pulmonary vascular permeability index (PVPI), were measured before cardiac arrest, ROSC 0 h, ROSC15 min, ROSC 30 min, ROSC 1 h, ROSC 2 h, ROSC 4 h and ROSC 6 h. All pigs were sacrificed with euthanasia at ROSC 6 h and the lungs were dissected for observing histopathological changes. The level of Na+ -K+ -ATPase, Ca2+ -ATPase, superoxide dismutase (SOD), Methane Dicarboxylic Aldehyde (MDA), Bcl-2, Bax, Caspase3 and apoptosis index (AI%) in lung were measured. Results The ROSC rate and ROSC 6hrs survival rate of in AS group was lower (P<0.01) than those of the VF group. The damages of lung in AS group were more severe than that in VF group by the results of enzymology and protein detection (Na+ -K+ -ATPase, Ca2+ -ATPase, SOD, MDA, Bax, Bcl-2 and Caspase3). AI% was higher in AS group (P<0.01). The deterioration of the indexes (OI, RI, DO2, Lac, Cdyn, Raw, EVLWI, PVPI) at all time points were more severe in AS group than those in VF group. Obvious filling-defect was found by the PET-CT scan of both groups, but not revealed by the isotope scan. Conclusions The lung injury after CA was closely related to the cause of CA rather than the external chest compression. Asphyxia induced more serious lung injury than ventricular fibrillation. Key words: Lung Injury; Cardiac Arrest; Cardiopulmonary Resuscitation; Asphyxia; Ventricular Fibrillation; Ischemia/reperfusion injury; Apoptosis; Nuclide scan; PET-CT