To Örebro University

Objective: To study the splanchnic metabolism and intestinal circulation in a porcine model with increased abdominal pressure.

Methods: In an experimental porcine study, performed under intravenous anaesthesia, five animals were subjected to gradually increasing intra-abdominal pressure (15 mmHg, 25 mmHg, and 35 mmHg) with pneumoperitoneum. Microdialysis and laser Doppler were the main outcome methods for monitoring the metabolic and circulatory changes.

Results: During stable anaesthesia and gradually increasing intra-abdominal pressure obtained by CO2-pneumoperitoneum, blood flow (microcirculation) was deprived and moderate signs of impaired splanchnic metabolism were recorded.

Conclusions: The model appears usable for studies of splanchnic metabolic consequences of intra-abdominal hypertension.

Objective: To investigate the early effects of intra-abdominal hypertension on intraabdominal metabolism and intestinal mucosal blood flow.

Design: Prospective animal study.

Setting: University hospital research laboratory.

Subjects: Three-month old domestic pigs of both sexes.

Interventions: The animals were anesthetized and ventilated. Fifteen animals were subjected to intra-abdominal hypertension of 30 mmHg for four hours by carbon dioxide insufflation. Seven animals served as controls.

Measurements and Main Results: Hemodynamic data, arterial blood samples and urine output were analyzed. Intraluminal laserdoppler flowmetry measured intestinal mucosal blood flow. Glucose, glycerol, lactate and pyruvate concentrations and lactate-pyruvate (l/p) ratio were measured intraperitoneally and intramurally in the small intestine and rectum by microdialysis. Intra-abdominal hypertension lowered the abdominal perfusion pressure by 12- 18 mmHg, reduced the intestinal mucosal blood flow by 45-63% and decreased urine output by 50-80%. While controls remained stable, glycerol concentrations increased at all locations at elevated intra-abdominal pressure, .pyruvate concentrations decreased and the l/p ratio increased intraperitoneally and intramurally in the small intestine. Glucose and lactate concentrations at all locations were only slightly affected or unchanged in both groups.

Conclusions: Intra-abdominal hypertension negatively influences intestinal blood flow and diuresis and causes early metabolic changes, indicating a discrete shift towards anaerobic metabolism. Metabolic changes, measured by intra-abdominal microdialysis, preferably by an intraperitoneal catheter, might be used as early markers of impaired visceral organ function in intra-abdominal hypertension and abdominal compartment syndrome.

Objective: This study aims to investigate the abdominal metabolic response and circulatory changes after decompression of intra-abdominal hypertension in a porcine model. Design: Prospective study with controls. Setting: University hospital research laboratory.

Subjects: Three-months old domestic pigs of both sexes. Interventions: The animals were anesthetised and ventilated. Nine animals had a pneumoperitoneum-induced intra-abdominal hypertension of 30 mmHg for six hours. Twelve animals had corresponding intra-abdominal hypertension for four hours followed by decompression and were monitored for another two hours.

Measurements and Main Results: Hemodynamics, urine output and arterial blood samples were analysed. Laserdoppler measured mucosal blood flow and urine output decreased with pressure induction and showed a statistically significant restitution after decompression. Glucose, glycerol, lactate and pyruvate concentrations and lactate-pyruvate (l/p) ratio were measured by microdialysis. Both groups developed distinct metabolic changes intraperitoneally at pressure induction including an increased l/p ratio as signs of organ hypoperfusion. In the decompression group the intraperitoneal l/p ratio normalised during the second decompression hour, indicating partially restored perfusion.

Conclusions: Decompression after four hours of intra-abdominal hypertension results in restoration of intestinal blood flow and normalised intraperitoneal metabolism.

Objectives: This study aims to evaluate intra-peritoneal (ip) microdialysis after endovascular aortic repair (EVAR) of ruptured abdominal aortic aneurysm (rAAA) in patients developing intra-abdominal hypertension (IAH), requiring abdominal decompression.

Design: Prospective study.

Material and methods: A total of 16 patients with rAAA treated with an emergency EVAR were followed up hourly for intra-abdominal pressure (IAP), urine production and ip lactate, pyruvate, glycerol and glucose by microdialysis, analysed only at the end of the study. Abdominal decompression was performed on clinical criteria, and decompressed (D) and non-decompressed (ND) patients were compared.

Results: The ip lactate/pyruvate (l/p) ratio was higher in the D group than in the ND group during the first five postoperative hours (mean 20 vs. 12), p = 0.005 and at 1 h prior to decompression compared to the fifth hour in the ND group (24 vs. 13), p = 0.016. Glycerol levels were higher in the D group during the first postoperative hours (mean 274.6 vs. 121.7 mu M), p = 0.022. The IAP was higher only at 1 h prior to decompression in the D group compared to the ND group at the fifth hour (mean 19 vs. 14 mmHg).

Conclusions: lp l/p ratio and glycerol levels are elevated immediately postoperatively in patients developing IAH leading to organ failure and subsequent abdominal decompression.