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 (HC1) 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 HCI 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 airoxygen (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 HC1 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.