Is intestinal tonometry a reliable method to detect histological changes after small bowel transplantation?

Introduction

Postoperative complications after intestinal transplantation can be attributed to hypothermic storage and reperfusion injury. In this study, we sought to obtain evidence that intestinal pCO₂ measurement can be a useful method for monitoring graft perfusion and early histological changes after small-bowel transplantation. Additionally, we evaluated the initial effects of isolated intestinal hypothermic perfusion (IHP) (at 4°C) on mucosal and serosal blood flow distribution, and we correlated these findings with other systemic and regional markers of mesenteric ischemia.

Methods

Eight dogs (23.3 ± 1.1 kg) were submitted to in situ IHP for 30 min, followed by a 180-min reperfusion period. The cardiac output, mesenteric vein and intestinal serosal blood flows (SMVBF and SBF, ultrasonic flowprobe), intestinal mucosal–arterial pCO₂ gradient (D_t-apCO₂, tonometry) and O₂-derived variables were evaluated.

Results

IHP induced a reduction in SMVBF (579 ± 53 to 321 ± 10 ml/min) and SBF (44.7 ± 3.2 to 29.1 ± 5.3 ml/min) and an increase in D_t-apCO₂ (2 ± 2.8 to 20.5 ± 4.5 mmHg). No alterations on systemic metabolic or O₂-derived variables were observed. The increase of the D_t-apCO₂ correlated with the grade of mucosal injury (Fig. 1).

Figure 1

Conclusion

IHP induces a proportional reduction on blood flow in all layers of the intestine, and none of the systemic markers of splanchnic ischemia predict the intestinal blood flow disturbances during the early phase of intestinal transplantation. In addition, intestinal pCO₂ measurement seems to be a useful way for monitoring graft perfusion and histological changes after hypothermic ischemia and reperfusion.