Gastrointestinal Microcirculation and Cardiopulmonary Function During Experimentally Increased Intra-abdominal Pressure

Objectives: The aim of this study was to assess gastric, intestinal, and renal cortex microcirculation parallel with central hemodynamics and respiratory function during stepwise increase of intra-abdominal pressure (IAP).

Design: Prospective, controlled animal study.

Setting: Research laboratory, University Hospital.

Subjects: Twenty-six anesthetized and mechanically ventilated pigs.

Interventions: Following baseline registrations, CO2 peritoneum was inflated (n = 20) and IAP increased stepwise by 10 mm Hg at 10 mins intervals up to 50 mm Hg and subsequently exsufflated. Control animals (n = 6) were not insufflated with CO2.

Measurements And Main Results: The microcirculation of gastric mucosa, small bowel mucosa, small bowel seromuscular layer, colon mucosa, colon seromuscular layer, and renal cortex were selectively studied at all pressure levels and after exsufflation using a four-channel laser Doppler flowmeter (Periflex 5000, Perimed). Central hemodynamic and respiratory function data were registered at each level and after exsufflation. Cardiac output decreased significantly at IAP levels above 10 mm Hg. The microcirculation of gastric mucosa, renal cortex and the seromuscular layer of small bowel and colon was significantly reduced with each increase of IAP. The microcirculation of the small bowel mucosa and colon mucosa was significantly less affected compared with the serosa (p < 0.01).

Conclusions: Our animal model of low and high IAP by intraperitoneal CO2-insufflation worked well for studies of microcirculation, hemodynamics, and pulmonary function. During stepwise increases of pressure there were marked effects on global hemodynamics, respiratory function, and microcirculation. The results indicate that intestinal mucosal flow, especially small bowel mucosal flow, although reduced, seems better preserved in response to intra-abdominal hypertension caused by CO2-insufflation than other intra-abdominal microvascular beds.