Validation of intramural intestinal microdialysis as a detector of intestinal ischaemia

The purpose of this study was to validate intestinal microdialysis as a detector of intestinal ischaemia using measurements of glucose, lactate and glycerol from the jejunal wall.

Based on a previous study, the cut-off levels for the presence of regional intestinal ischaemia were defined for microdialysis glucose, lactate, glycerol and the lactate/glucose ratio. Changes of 60% in the metabolic compounds measured after 100 min were defined as the cut-off level for ischaemia. The cut-off levels were tested in a randomized, single-blinded study. Ten pigs were used; occlusive ischaemia was performed by clamping a segment of the mesentery to the intestine. Four catheters were inserted per pig, two in the ischaemic segment and two in the non-ischaemic segment. All catheters were numbered, randomly allocated and inserted in the intestine by the staff at the institute and unknown to the investigators.

One pig was excluded because the clamping was insufficient. Technical problems with the catheters were registered in 15% of cases owing to damage of the microdialysis membrane, dislocation, or incorrect placement. The predictive values of presence of ischaemia for glucose, lactate, glycerol and the lactate/glucose ratio were: 0.91, 1,0.85 and 0.92, respectively.

Using a 60% cut-off limit measured after 100 min, intestinal ischaemia can be detected and excluded using intestinal microdialysis, but some technical problems remain that need further investigation.