SMALL-BOWEL OBSTRUCTION AND THE EFFECTS OF LIDOCAINE, ATROPINE AND HEXAMETHONIUM ON INFLAMMATION AND FLUID LOSSES

Background: The profuse fluid losses and morbidity of patients sufferi ng from obstructive ileus are closely related to inflammatory changes in the obstructed bowel wall. Previous experimental studies have shown that use of steroids and NSAIDs can reduce fluid losses in obstructiv e ileus. In the present study, we investigated the effects of lidocain e on fluid losses since local anesthetics have been shown to possess w ide and potent antiinflammatory properties. Hexamethonium and atropine were used to study the importance of the autonomic nervous system in bowel obstruction. Method: Experiments were performed in rats in vivo. After 18 h of total obstruction of the jejunum by thread ligation, a segment of the obstructed jejunum was placed in a chamber with intact nervous and vascular supply and net fluid transport was continuously r egistered by a gravimetric technique. Extravasation of Evans blue albu min as marker of inflammation was quantified by spectrophotometry. Res ults: Hexamethonium (10 mg . kg(-1) i.v.) significantly inhibited net fluid secretion (P<0.05), while atropine (0.25 mg . kg(-1) i.v.) had n o significant effect. Net fluid secretion was reversed into absorption following an intravenous bolus dose of lidocaine (2 mg . kg(-1)) (P<0 .01) and topical administration of lidocaine (20 mg) on the serosa of the obstructed gut (P<0.01). Single topical administration of lidocain e (20 mg) immediately before ligation significantly reduced net fluid secretion (P<0.05) and inflammation (P<0.05) in the obstructed bowel 2 0 h post-ligation compared to obstructed controls. Conclusion: Lidocai ne significantly inhibited or prevented fluid losses when administered intravenously or topically to be obstructed gut. Mechanisms of action could be inhibition of nerve reflexes involved in fluid secretion and by inhibition of inflammation in the bowel wall. The inhibition of fl uid losses by hexamethonium further supports the importance of the aut onomic nervous system in the pathophysiology of bowel obstruction.