Objectives: Alteration of erythrocyte osmotic resistance, with increment of reticulocytes, is common in emphysema. This fragility is probably due to an altered fatty acid membrane composition from lipid peroxidation, a reaction triggered by the disease-related increment of reactive oxidative species. We analysed the effects of lung volume reduction surgery (LVRS) on this anomaly compared with respiratory rehabilitation (RR) therapy.
Methods: We retrospectively compared 58 male patients with moderate-to-severe emphysema who underwent LVRS with 56 similar patients who underwent standardized RR. Respiratory function parameters, erythrocyte osmotic resistance and antioxidant enzymes levels were evaluated before and 6 months after treatments.
Results: Significant improvements in respiratory function, exercise capacity, unsaturated fatty acid content (+10.0%, P = 0.035), erythrocyte osmotic resistance (hyperosmolar resistance -21.0%, P = 0.001; hyposmolar resistance -18.0%, P = 0.007) and erythrocyte antioxidant enzymes [superoxide dismutase (SOD) +60.0%, P < 0.001; glutathione peroxidase +39.0%, P = 0.004 and glutathione reductase +24.5%, P = 0.008] were observed after surgery. In the RR group, we did not find any significant improvements in osmotic resistance, although respiratory and functional parameters were significantly improved. Correlation analysis in the surgical group showed that the reduction in residual volume (RV) significantly correlated the normalization of hyperosmotic (P = 0.019) and hyposmotic resistances (P = 0.006), the decrease in the absolute number of reticulocytes (P = 0.037) and increase in SOD (P < 0.001).
Conclusions: LVRS improved unsaturated fatty acid content, erythrocyte osmotic resistance and levels of erythrocyte antioxidant enzymes compared with RR. Correlations between erythrocyte osmotic resistance and antioxidant intracellular enzymes with RV suggest that reduction in lung hyperinflation with the elimination of inflammatory emphysematous tissue may explain such improvements after surgery.
Keywords: Emphysema; Erythrocyte osmotic resistance; Lung volume reduction surgery; Oxidative stress.