Effects of mechanical ventilation with heliox-oxygen on acute lung injury in rabbits

Abstract

Objective To evaluate the effects of mechanical ventilation with heliox-oxygen on acute lung injury(ALI)in rabbits. Methods Thirty healthy New Zealand male rabbits, weighing 2.2-2.4 kg, were randomly divided into 3 groups(n=10 each)using a random number table: control group(C group), ALI group and mechanical ventilation with helium-oxygen group(HO group). The right common carotid artery was cannulated for fluid administration and blood sampling in the rabbits anesthetized with urethane.In ALI and HO groups, 1.2 ml/kg hydrochloric acid(HCl)of pH value 1.0 was injected into the right bronchus, followed by 2 ml air injection, and 5 min later 0.8 ml/kg HCl of pH value 1.0 was injected into the left bronchus, followed by 2 ml air injection.In C group, the equal volume of normal saline was given as previously described.After ALI, the rabbits were mechanically ventilated with air-oxygen(air 50%-oxygen 50%)in C and ALI groups, or with helium-oxygen(helium 50%-oxygen 50%)in HO group.Mechanical ventilation(tidal volume 8 ml/kg, respiratory rate 30 breaths/min, inspiratory/expiratory ratio 1∶1)lasted for 4 h in the three groups.At 30 min before and after HCl injection(T0, 1)and 1, 2, 3 and 4 h of ventilation(T2-T5), arterial blood samples were collected to detect the levels of surfactant-protein(SP-A)in serum by enzyme-linked immunosorbent assay.The animals were sacrificed at T5, and lungs were removed for examination of the pathologic changes with light microscope.The wet to dry lung weight ratio(W/D ratio)was calculated. Results Compared with group C, the levels of SP-A in serum were significantly increased at T1-T5, and W/D ratio was increased in ALI and HO groups.Compared with group ALI, the levels of SP-A in serum were significantly decreased at T5, and W/D ratio was decreased in HO group. Conclusion Mechanical ventilation with heliox-oxygen can reduce ALI in rabbits. Key words: Respiration, artificial; Helium; Oxygen; Respiratory distress syndrome, adult