The effects of water-soluble contrast media on luminal distension and blood flow in closed loops of small bowel in minipigs.

The effects of iohexol, sodium diatrizoate, and physiologic saline on intestinal distension and circulation were observed for 8 h in nine minipigs with closed-loop obstruction of the small bowel. The two contrast media led to an elevation of intraluminal pressures when initially instilled at pressures above 35 mm Hg. These elevated pressures were not high enough to cause rupture of the bowel wall. Both contrast media caused severe mucosal ischaemia as judged from histologic sections, loops containing sodium diatrizoate more so than iohexol. The blood circulation of the bowel wall, examined by laser Doppler flowmetry, was after 6 to 8 h reduced to about 10% of the values of non-obstructed bowel at intraluminal pressures of about 70 mm Hg in the loops with iohexol and sodium diatrizoate. The correlation to osmolality was obvious when compared with concurrent observations in the loops with physiologic saline. In the bowel loops filled with physiologic saline the pressure fell to 5 mm Hg after 8 h, regaining approximately one-third of pre-instillation levels of blood flow. On microscopy these bowel loops had a nearly normal mucosa.