Observations of lung function during forming process of acquired pectus excavatum in rats

Abstract

Objective To observe the changes of lung function during forming process of acquired pectus excavatum. Methods A total of 40 4-week-old Sprague-Dawley rats were divided randomly into experimental and control groups (n=20 each). The 5-7th couples of rib cartilage were resected parasternum for pectus excavatum model in experimental group but no intervention in control group.Pulmonary functions were detected with animal lung function analysis system at Day 3 and Week 4 after operation including the parameters of inspiratory resistance (Ri), expiratory resistance (Re), compliance of lung (Cl), minute ventilation (MVV), forced vital capacity (FVC), forced expiratory volume in the first 0.2 seconds (FEV0.2), FEV0.2/FVC%, exhaled 50%FVC when the quantity of flow velocity (FEF50%) and forced peak expiratory flow (PEF). The data were compared between groups and analyzed statistically. Results There were faster respiratory rate within 1 week after operation and then funnel chest formed gradually in animal model.As a result of pulmonary function, the values of experimental and control groups at Day 3 after operation were as follows: Ri (1.16±0.21) cmH2O·ml-1·s-1 and (0.73±0.26) cmH2O·ml-1·s-1 (P=0.00), Re (0.86±0.30) cmH2O/ml/s and (0.58±0.16) cmH2O/ml/s (P=0.01), Cl (0.05±0.01) cmH2O/ml and (0.09±0.02) cmH2O/ml (P=0.00), FV(3.69±0.10)ml and (3.89±0.19) ml (P=0.00), FEV0.2 (3.28±0.40) ml and (3.58±0.15) ml (P=0.02). And then, the values were Ri (0.88±0.17) cmH2O·ml-1·s-1 and (0.66±0.10) cmH2O·ml-1·s-1 (P=0.00), FVC (5.76±0.52) ml and (5.47±0.20) ml (P=0.05) at Week 4.The value of Ri was higher in experimental group than that in control with statistical significance at Day 3 or Week 4 after operation (P 0.05). Conclusions The compliance of chest wall and lung decreases with increased inspiratory and expiratory resistance during the forming process of model pectus.And lower thoracic compliance is maintained when pectus deformity forms but pulmonary function remains normal because of re-adaption. Key words: Pectus excavatum; Lung function; Rat