Mechanical Intestinal Obstruction in a Porcine Model: Effects of Intra-Abdominal Hypertension. A Preliminary Study

Abstract

IntroductionMechanical intestinal obstruction is a disorder associated with intra-abdominal hypertension and abdominal compartment syndrome. As the large intestine intraluminal and intra-abdominal pressures are increased, so the patient’s risk for intestinal ischaemia. Previous studies have focused on hypoperfusion and bacterial translocation without considering the concomitant effect of intra-abdominal hypertension. The objective of this study was to design and evaluate a mechanical intestinal obstruction model in pigs similar to the human pathophysiology.Materials and MethodsFifteen pigs were divided into three groups: a control group (n = 5) and two groups of 5 pigs with intra-abdominal hypertension induced by mechanical intestinal obstruction. The intra-abdominal pressures of 20 mmHg were maintained for 2 and 5 hours respectively. Hemodynamic, respiratory and gastric intramucosal pH values, as well as blood tests were recorded every 30 min.ResultsSignificant differences between the control and mechanical intestinal obstruction groups were noted. The mean arterial pressure, cardiac index, dynamic pulmonary compliance and abdominal perfusion pressure decreased. The systemic vascular resistance index, central venous pressure, pulse pressure variation, airway resistance and lactate increased within 2 hours from starting intra-abdominal hypertension (p<0.05). In addition, we observed increased values for the peak and plateau airway pressures, and low values of gastric intramucosal pH in the mechanical intestinal obstruction groups that were significant after 3 hours.ConclusionThe mechanical intestinal obstruction model appears to adequately simulate the pathophysiology of intestinal obstruction that occurs in humans. Monitoring abdominal perfusion pressure, dynamic pulmonary compliance, gastric intramucosal pH and lactate values may provide insight in predicting the effects on endorgan function in patients with mechanical intestinal obstruction.

Time-course evaluation of intestinal structural disorders in a porcine model of intra-abdominal hypertension by mechanical intestinal obstruction

“…The MIO model was previously described in a pilot validation study [ 23 ]. The project was approved by the Ethical Committee for Animal Welfare adopted by the center (reference CEBA-CCMIJU 09/25) and by the Council of Agriculture and Rural Development of the Regional Government of Extremadura.…”

“…The animals were divided in one control group (C, n = 5) and two experimental groups (G1 and G2) where the IAP was a consequence of experimental MIO model already established [ 23 ] ( Fig 2 ). This model simulated the IAH through a forced laparoscopic suture at the ileocaecal valve, to achieve mechanical obstruction, and perfusion of 0.9% sodium chloride solution into the colon to increase the IAH subsequently.…”

“…Besides standard parameters of systemic perfusion, intestinal parameters of high diagnostic value such as the abdominal perfusion pressure (APP) [ 13 , 15 , 16 ], the gastric intramucosal pH (pHi), lactic acid (Lc) [ 16 – 20 ] and indocyanine green plasma disappearance rate (ICG-PDR) [ 21 , 22 ] are currently used as early predictors of acidosis and intestinal ischemia ( Fig 1 ). In recently published work [ 23 ], a porcine model of IAH by MIO was validated. The APP, pHi and Lc were three predictors for end-organ function including the bowel, but the relationship between these and the intestinal damage is poorly understood.…”

Abdominal pressure and gastrointestinal function: an inseparable couple?

“…The negative effect of IAH on splanchnic microcirculation appears to be dose-dependent [67]. In an experimental study in rabbits, microvascular blood flow decreased continuously during the application of IAP 15 mm Hg for 6 h, whereas application of IAP 25 mm Hg for 6 h led to dramatic reduction in microcirculatory blood flow (80% reduction from baseline) and intestinal permeability [66].…”

Early impact of abdominal compartment syndrome on liver, kidney and lung damage in a rodent model

“…As the association of hypovolemia and IAH is frequent in various pathological conditions, including trauma, haemorrhagic shock and septic shock, a new ACS model seems warranted. This model should be able to maintain IAP values within an acceptable range during a prolonged interval, intending to maintain a level of IAH that, when combined with hypovolemia, would cause organ failure resembling human ACS [11][12][13]. We hypothesize that hypovolemia could compound the negative effects of IAH on the lungs and peripheral organs.…”