Effect of transgastric natural orifice transluminal endoscopic surgery peritoneoscopy on abdominal organ microcirculation: an experimental controlled study

Background and Aims On-demand insufflation during endoscopic peritoneoscopy causes wide variations in intra-abdominal pressure. Its effects on splanchnic microcirculation may differ from those of steady intra-abdominal pressure, because pressure characteristics affect crucial intravascular hemodynamic forces—pressure and shear—adapting flow to local metabolic needs. Our aim was to assess the effect of natural orifice transluminal endoscopic surgery (NOTES) peritoneoscopy on splanchnic microcirculatory blood flow. Methods Twenty-one swine were randomized to the following: cholecystectomy by transgastric NOTES (n = 8), cholecystectomy by standard laparoscopy (Lap) (n = 8), and a sham group (n = 5). During NOTES, CO 2 was manually insufflated with a maximum allowed pressure of 30 mm Hg. In the Lap group, intra-abdominal pressure was maintained at 14 mm Hg. Systemic hemodynamics were measured, and microcirculatory blood flow was quantified by using colored microspheres. Results Mean intra-abdominal pressure was lower in NOTES than in the Lap group ( P  = .038). In both groups, cardiac index and preload remained unchanged, whereas systemic vascular resistances increased over time, with a lesser increase in the Lap group (2-way analysis of variance; P  = .041). In pneumoperitoneum groups, microcirculatory blood flow decreased similarly in the renal medulla, stomach, small bowel, colon, and mesocolon by 30%, 45%, 34%, 32%, and 37%, respectively. In NOTES, there was a greater microcirculatory blood flow decrease in the renal cortex (NOTES 41% vs Lap 35%; P  = .044) and mesentery (NOTES 44% vs Lap 38%; P  = .041). Conclusions These findings suggest that both types of pneumoperitoneum have similar physiologic effects on microcirculatory blood flow. However, on-demand pneumoperitoneum (NOTES group) caused a greater microcirculatory blood flow decrease in areas with low metabolic needs, redistributing blood flow toward metabolically active areas.