Macroscopic changes during negative pressure wound therapy of the open abdomen using conventional negative pressure wound therapy and NPWT with a protective disc over the intestines

BACKGROUND: Higher closure rates of the open abdomen have been reported with negative pressure wound therapy (NPWT) than with other wound management techniques. However, the method has occasionally been associated with increased development of fistulae. We have previously shown that NPWT induces ischemia in the underlying small intestines close to the vacuum source, and that a protective disc placed between the intestines and the vacuum source prevents the induction of ischemia. In the present study we compare macroscopic changes after 12, 24, and 48 hours, using conventional NPWT and NPWT with a protective disc between the intestines and the vacuum source. METHODS: Twelve pigs underwent midline incision. Six animals underwent conventional NPWT, while the other six pigs underwent NPWT with a protective disc inserted between the intestines and the vacuum source. Macroscopic changes were photographed and quantified after 12, 24, and 48 hours of NPWT. RESULTS: The surface of the small intestines was red and mottled as a result of petechial bleeding in the intestinal wall in all cases. After 12, 24 and 48 hours of NPWT, the area of petechial bleeding was significantly larger when using conventional NPWT than when using NPWT with the protective disc (9.7 ± 1.0 cm(2 )vs. 1.8 ± 0.2 cm(2), p < 0.001, 12 hours), (14.5 ± 0.9 cm(2 )vs. 2.0 ± 0.2 cm(2), 24 hours) (17.0 ± 0.7 cm(2 )vs. 2.5 ± 0.2 cm(2 )with the disc, p < 0.001, 48 hours) CONCLUSIONS: The areas of petechial bleeding in the small intestinal wall were significantly larger following conventional NPWT after 12, 24 and 48 hours, than using NPWT with a protective disc between the intestines and the vacuum source. The protective disc protects the intestines, reducing the amount of petechial bleeding.