Abstract 19149: Pulmonary Oxidative Stress, Reperfusion Injury and Lung Tissue Damage During Cardiac Surgery: The Outcome of an Experimental Trial in a Porcine Model
Background and Objective: The incidence of pulmonary complications following cardiac surgery remains high and is associated with increased in-hospital mortality and costs. Established surgical practice predominantly regards diverting the pulmonary circulation and deflating the lungs from mechanical ventilator (to facilitate surgical exposure) as a safe approach during the period of cardiopulmonary bypass (CPB) and cardioplegic arrest (CA). In this experimental trial we investigate for the first time the incidence of pulmonary dysfunction, ischemia, oxidative stress, and lung tissue damage associated with cardiac surgery in a porcine experimental model and CPB and CA.
Methods: Landrace white female pigs (~60kg) were randomised to either median sternotomy alone (Control; n=6) or with CPB (80 minutes) and CA with intermittent antegrade cold blood cardioplegia delivered at 20 minutes intervals (CPB+CA; n=7). Standardised anaesthetic, surgical and perfusion protocols were used in accordance with Home Office Guidance. During CPB the lungs were left deflated as per routine surgical practice. Serial blood samples and lung biopsies were collected at baseline, prior weaning CPB (ischemia), and 1 hour following CPB weaning (recovery). Functional, inflammatory, oxidative, histo-pathological, micro-vascular permeability and apoptosis variables were compared.
Results: In the CPB+CA group there was marked functional deterioration (respiratory index and alveolar-arterial oxygenation gradients; both p<0.05), significant pulmonary ischemia (reduced ATP/ADP and ATP/AMP ratios; both p<0.05), evidence of lung apoptosis (caspase-3 activity), increased pulmonary micro-vascular leakage (p<0.05) and pulmonary tight junctions fragmentation (immunohistochemistry). None of these findings was observed in the Control group.
Conclusions: The established practice of cardiac surgery does not protect the lungs during CPB and CA and it is associated with pulmonary dysfunction, ischaemia, apoptosis, and marked lung tissue damage. Novel interventions of lung protection during cardiac surgery are required to minimise these detrimental effects.
- © 2013 by American Heart Association, Inc.