P0960 - Displacement-based Safety Monitoring for Distraction Enterogenesis

Introduction
Short bowel syndrome (SBS) is the most common cause of pediatric intestinal failure. Distraction enterogenesis—the use of longitudinal mechanical force to induce small-intestinal elongation and absorptive capacity—is a promising treatment strategy. No method of distraction enterogenesis has been proven safe for clinical translation. The Michigan Endoluminal Distraction Device (MENDD) effectively lengthens the bowel, increases absorptive capacity, and can be deployed and removed through a stoma. The purpose of this study is to establish the safety profile of a previously described late-model prototype of this device prior to clinical translation (Fig1A).

Methods
MENDD were placed into 10–30-cm segments of isolated jejunum in anesthetized 30–40-kg Yorkshire pigs. A spring scale was used to determine strain (percent change in bowel length with increasing applied force). The inner catheter of the MENDD was advanced up to 5 cm with both textured balloon attachments inflated. Bowel distraction length was recorded and a laser doppler flow meter measured blood flow to the bowel wall at various points.

Results
Bowel displacement vs. force
The relationship between distracting force and resultant strain was nearly linear up to 175 gf and 70% strain (2.6 gf produces 1% additional strain) with a decreasing slope above 175 gf (Fig1B). Force up to 400 gf produced no visible damage to the bowel wall.

Blood flow vs. bowel stretch
Blood flow to the bowel remained above 50% of baseline with inner-catheter displacement up to 3 cm (Fig1C). This produced 56% strain (1.3 cm bowel distraction) and equated to 145 gf according to the regression line from the force-strain relationship (Fig1D). Additional catheter advancement decreased blood flow with minimal additional distraction.

Conclusion
Displacement-based safety monitoring for the MENDD is feasible and achieves safe bowel distraction within a predictably safe range of bowel perfusion.