Small-bowel obstruction and the effects of lidocaine, atropine and hexamethonium on inflammation and fluid losses.
Palabras clave
Abstracto
BACKGROUND
The profuse fluid losses and morbidity of patients suffering 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 obstructive ileus. In the present study, we investigated the effects of lidocaine on fluid losses since local anesthetics have been shown to possess wide and potent anti-inflammatory properties. Hexamethonium and atropine were used to study the importance of the autonomic nervous system in bowel obstruction.
METHODS
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 registered by a gravimetric technique. Extravasation of Evans blue albumin as marker of inflammation was quantified by spectrophotometry.
RESULTS
Hexamethonium (10 mg.kg-1 i.v.) significantly inhibited net fluid secretion (P < .05), while atropine (0.25 mg.kg-1 i.v.) had no 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 lidocaine (20 mg) immediately before ligation significantly reduced net fluid secretion (P < 0.05) and inflammation (P < 0.05) in the obstructed bowel 20 h post-ligation compared to obstructed controls.
CONCLUSIONS
Lidocaine significantly inhibited or prevented fluid losses when administered intravenously or topically to the 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 fluid losses by hexamethonium further supports the importance of the autonomic nervous system in the pathophysiology of bowel obstruction.
