Pretreatment with endothelium-derived nitric oxide synthesis modulators on gastrointestinal microcirculation during NOTES: an experimental study.

Abstract

On-demand endoscopic insufflation during natural orifice transluminal endoscopic surgery (NOTES) adversely affects microcirculatory blood flow (MBF), even with low mean intra-abdominal pressure, suggesting that shear stress caused by time-varying flow fluctuations has a great impact on microcirculation. As shear stress is inversely related to vascular diameter, nitric oxide (NO) production acts as a brake to vasoconstriction. To assess whether pretreatment by NO synthesis modulators protects gastrointestinal MBF during transgastric peritoneoscopy. Fourteen pigs submitted to cholecystectomy by endoscope CO2 insufflation for 60min were randomized into 2 groups: (1) 150mg/kg of N-acetyl cysteine (NAC, n=7) and (2) 4ml/kg of hypertonic saline 7.5% (HS, n=7), and compared to a non-treated NOTES group (n=7). Five animals made up a sham group. Colored microspheres were used to assess changes in MBF. The average level of intra-abdominal pressure was similar in all groups (9mmHg). In NOTES group microcirculation decrease compared with baseline was greater in renal cortex, mesocolon, and mesentery (41, 42, 44%, respectively, p<0.01) than in renal medulla, colon, and small bowel (29, 32, 34, respectively, p<0.05). NAC avoided the peritoneoscopy effect on renal medulla and cortex (4 and 14% decrease, respectively) and reduced the impact on colon and small bowel (20% decrease). HS eliminated MBF changes in colon and small bowel (14% decrease) and modulated MBF in renal medulla and cortex (19% decrease). Neither treatment influenced mesentery MBF decrease. Both pretreatments can effectively attenuate peritoneoscopy-induced deleterious effects on gastrointestinal MBF.