The microvascular blood flow in a small intestinal loop located at the surface of the anterior abdominal wall, relative to the baseline value, when exposed to topical negative pressures of −50, −70 and −120 mmHg. The results shown are the means of 10 measurements ± the standard error on the mean (SEM). Statistical analysis was performed using the Mann–Whitney test. Significance was defined as P < 0·05 (*), P < 0·01 (**), P < 0·001 (***) and P > 0·05 (not significant, n.s.).