Fluorometric evaluation of large and small intestinal ischaemia in the horse

Arteriovenous (ischaemic strangulating obstruction, ISO) and venous obstructions (haemorrhagic strangulating obstruction, HSO) were created for 70 min in the small intestine of eight anaesthetised horses, and ISO was created in four horses for 2 h and four horses for 3 h at the sternal and diaphragmatic flexures of the large colon. Five minutes following release of the occlusions, sodium fluorescein 20 per cent (0.5 mg/kg bodyweight intravenously) was administered. Serial quantitative measurements of serosal surface fluorescence of the injured segments and a control segment were made at 2, 10, 15, 20 and 30 mins using a fibreoptic perfusion fluorometer. Significant differences in fluorescence were seen in small intestine segments between HSO vs control, ISO vs HSO, but not ISO vs control segments. In the large colon, significant differences were seen between the fluorescence in the ischaemic 3 h ventral colon and control segments, and a trend for difference in fluorescence between the 2 and 3 h ischaemic segments. Differences in fluorescence between 2 vs 3 h dorsal colon segments and 2 or 3 h dorsal colon vs control segments were not significant.