Histopathological effects of lidocain and methylprednisolone in experimental acute lung injury

Introduction and purpose

Acute lung injury (ALI) resulted from acid aspiration is an important problem for anaesthesia and intensive care. In our study, we aimed to compare the histopathological effects of lidocain and methylprednisolone used in the treatment of ALI developed by acid aspiration.

Materials and methods

With the approval of the faculty ethic board, we formed three groups randomly from 30 rabbits as a 0.9% NaCl control group (Group C, n = 10), a lidocain group (Group L, n = 10), and a methylprednisolone group (Group M, n = 10). The subjects were applied tracheotomy under anaesthesia. Anaesthesia induction and maintenance, 2% isoflurane, 50% oxygen, 50% N₂O were used. Later all the subjects were given 3 ml/kg of 0.1 N HCl (pH 2) as drops intratracheally. Following this, the subjects in group C were administered 2 ml/kg per hour continious 0.9% NaCl infusion and 2 ml/kg intravenous bolus, those in Group L 2 ml/kg per hour continuous infusion and 2 mg/kg intravenous bolus lidocain, and those in Group M 30 mg/kg intravenous bolus single dose methylprednisolone. ALI development was determined by PaO₂/FiO₂. After 6 hour mechanical ventilation, the subjects were sacrificed. ALI was scored histopathologically as to alveolar congestion, hemorrhage, neutrophil infiltration or aggregation, and alveolar wall thickness–Hyalin membrane occurrence. Each item was graded as 0 = least injury, 1 = slight injury, 2 = moderate injury, 3 = severe injury, 4 = maximum injury. The groups were statistically evaluated with Kruskal–Wallis variance analysis.

Results

Average total ALI scores of the groups were 8.80 ± 1.54 for group C, 4.06 ± 1.07 for group L and 2.80 ± 1.03 for group M. ALI was found to be higher in group C than in groups L and M (P < 0.01). Likewise, ALI was higher in group L than in group M (P < 0.01) (Fig. 1).

Figure 1

Comparison of ALI in groups (* P < 0.01).

Conclusion

We have the conclusion that lidocain and methylpred-nisolone are the drugs to be used for reducing histophatological effects of ALI, and methylprednisolone is more effective than lidocain. However, we are of the conclusion that our findings should be supported with clinical studies.