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Background: To investigate whether the compartment pressure of the rectus sheath (CPRS) reflects the intra-abdominal pressure (IAP) under various conditions of intra-abdominal hypertension (IAH) in a pig model., Design: Prospective experimental study with in vivo pressure measurements., Setting: Institute for Clinical and Experimental Surgery, University of Saarland., Animals: Seven domestic male pigs (body weight 34.8+/-2.5 kg)., Interventions: Stepwise increase and decrease of IAP by means of CO(2) pneumoperitoneum. Continuous direct measurement of the IAP and correspondent indirect IAP measurement techniques including analysis of intravesical pressure (IVP), femoral vein pressure (FVP), and CPRS., Results: Bland-Altman analysis comparing direct IAP measurement with correspondent CPRS showed good agreement for IAP between 12 mm Hg and 30 mm Hg (bias -0.5 mm Hg, lower and upper limits of agreement (LLA/ULA) -3.5/2.5 mm Hg). FVP (bias -0.3 mm Hg, LLA/ULA -2.3/1.6 mm Hg) and IVP (bias 0.4 mm Hg, LLA/ULA -2.1/2.9 mm Hg) demonstrated similar results compared with direct IAP measurement. Agreement was worse for all indirect IAP measurement techniques for IAP<12 mm Hg., Conclusions: CPRS accurately reflects IAP for IAP> or =12 mm Hg. Accuracy is similar to established indirect IAP measurement techniques., (Copyright 2010 Elsevier Inc. All rights reserved.)

Background: The metabolic changes associated with carbon dioxide (CO(2)) pneumoperitoneum include metabolic acidosis and lowered intra-abdominal pH values. An experimental study was performed to evaluate the effect of CO(2) pneumoperitoneum on esophageal and gastric smooth muscle sensitivity in response to several agonists., Methods: Wistar albino rats, weighing 200-250 g, were allocated into three groups. After anesthetization with ketamine hydrochloride and xylazine, abdominal esophagus, gastroesophageal junction, and gastric fundus were removed via median laparotomy in the control group. In the oxygen (O(2)) group, a 16G catheter was inserted into the abdomen above the umbilicus and insufflated with 95% O(2) and 5% CO(2) with a pressure of 10 mm Hg. In the CO(2) group, CO(2) was insufflated at the same pressure within the same time and the tissues were removed at the end of a 60 min period of pneumoperitoneum. Abdominal esophageal segment (n:6), gastroesophageal junction (n:6) and gastric fundus (n:12) were suspended under 0.5 to 2 g resting tension in Tyrode solution in organ baths. Contraction responses were obtained by carbachol and serotonin and relaxation responses were evaluated by isoproterenol in each group. All the responses were compared by nonparametric Kruskal Wallis test., Results: Carbachol and serotonin induced contractile responses of abdominal segments, gastroesophageal junction, and gastric fundus showed no difference between the control, O(2), and CO(2) groups (P > 0.05). Isoproterenol relaxation responses of the three groups were also not statistically different from each other (P > 0.05)., Conclusion: CO(2) pneumoperitoneum of 60 min has no influence on esophageal and gastric smooth muscle responses to different agonists in rats., (Copyright 2010 Elsevier Inc. All rights reserved.)

Background: Experimental evidence supporting the safety of laparoscopic intervention during sepsis is limited. The purpose of this study was to evaluate the effects of pneumoperitoneum on immunologic and hemodynamic responses to peritoneal sepsis., Materials and Methods: A porcine model of peritonitis was created using an intraperitoneal autologous fecal inoculum. Pigs were then subjected to one of four procedures 24 h postinoculation (n = 6 per group): laparotomy, CO(2) laparoscopy, helium laparoscopy, and anesthesia only (1.5% isoflurane in 100% O(2), mechanical ventilation). Venous blood samples were obtained prior to inoculation, and at 24 (prior to procedure), 30, 48, 72, and 96 h postinoculation to determine white blood count (WBC) with differential, C-reactive protein (CRP), tumor necrosis factor, and bacteremia. Heart rate, end-tidal CO(2) (ETCO(2)), mean arterial blood pressure (MAP), and arterial blood gas variables were also measured at baseline and every 30 min throughout the procedure., Results: Postoperative blood cultures confirmed systemic bacteremia in all groups at all time periods postinoculation. Following inoculation, WBC, band cell count, and CRP remained elevated above baseline in all groups throughout the study (P < 0.01). However, no significant differences in these parameters were observed among groups. In the CO(2) laparoscopy group, MAP, ETCO(2), and arterial pCO(2) were increased above baseline, while pH was decreased throughout the procedure (P < 0.01)., Conclusions: In this animal model of peritonitis, CO(2) pneumoperitoneum induced hypercapnia, acidemia, and systemic hypertension intraoperatively, without a discernable effect on systemic immune function.

Background: An intra-abdominal pressure (IAP) of 15 mm Hg reduces intestinal organ perfusion in humans and animals, but it is unknown whether this results in organ damage. The purpose of this study was to evaluate if an IAP of 15 mm Hg lasting for 24 h in a porcine model will lead to morphologic impairment of intestinal and adjacent organs., Methods: We examined 12 intubated and anesthetized domestic pigs (51.8 +/- 4.4 kg). Using CO2 pneumoperitoneum, the IAP was raised to 15 mm Hg (study group, n = 6) for an investigation period of 24 h. In the control group, the IAP remained unchanged. Investigated parameters were cardiac output (CO), peak inspiratory pressure (PIP), and urine output (UO), as well as serum creatinine, alanine aminotransferase (ALT), lactate, lipase, and alkaline phosphatase (AP). Additionally, histopathological examinations were performed.Results. In comparison to the control, CO did not change, while UO decreased significantly by 59% and PIP increased significantly to more than 30 mbar. Serum ALT and AP increased significantly while there was no change in creatinine, lactate, and lipase. Histopathologically, low-grade liver necrosis (12% of liver lobuli), low-grade proximal tubular epithelial necrosis, and low bowel mucosal damage were observed.Conclusion. In this porcine model, an IAP of 15 mm Hg lasting for 24 h was found to result in functional and morphologic impairment of lungs, liver, kidneys, and bowel. These results imply that a prolonged IAP of 15 mm Hg predisposes to multiorgan dysfunction and that a safe duration of increased IAP still has to be determined.

Pneumoperitoneum (PP) is associated with oliguria and increased plasma arginine vasopressin (AVP) levels. This study investigated the role of AVP in the pathogenesis of oliguria due to PP. Anesthetized and ventilated rats (n = 12) were subjected for 1 h to carbon dioxide PP with an intra-abdominal pressure of 8 mmHg or, as control, at 0 mmHg, before the determination of plasma AVP level. Another group of rats (n = 48) subjected to PP or control conditions was pretreated with the AVP V2 receptor antagonist, OPC-31260 (5 mg/kg), or vehicle, and their renal parameters were measured. Glomerular filtration rate (GFR) was determined by inulin clearance in an additional group of rats (n = 12) subjected to PP with or without pretreatment with OPC-31260. Rats subjected to PP had higher plasma AVP levels than did controls (17.3 +/- 8.1 pg/ml vs 1.5 +/- 0. 6 pg/ml, P < 0.05). In rats pretreated with vehicle, PP decreased urine output, excretion of water, and urea nitrogen, leading to reduced serum osmolality and serum sodium levels as well as elevated blood urea nitrogen levels. OPC-31260 pretreatment improved urine output, excretion of water, and urea nitrogen, thereby preventing changes in serum osmolality, serum sodium levels, and blood urea nitrogen levels. OPC-31260 pretreatment did not affect GFR. Results suggest that plasma AVP contributes to the oliguria due to PP. OPC-31260 may be useful in treating the water retention associated with PP., (Copyright 1998 Academic Press.)

Laparoscopy has been considered a relative contraindication in pregnant patients because the CO2 pneumoperitoneum may cause maternal and/or fetal hypotension, acidosis, hypercarbia, hypoxia, changes in cardiac output, or uterine artery blood flow. These potential changes were studied in an established animal pregnancy model. Twelve gravid ewes (116-120 days gestation) underwent catheterization of maternal femoral artery and vein, fetal hindlimb artery and vein, insertion of a uterine artery flow probe, and pulmonary artery catheter. Six animals underwent creation of a CO2 pneumoperitoneum (10 mm Hg for 30 min; 15 mm Hg for 30 min). Six control animals were studied without a pneumoperitoneum. The following parameters were recorded at baseline and at preset time points: cardiac output (CO), uterine blood flow (UtBF), amniotic cavity pressure (ACP), end-tidal CO, (Et CO2), maternal and fetal heart rate (HR), blood pressure (BP), and lactate, glucose, and arterial blood gasses. Percent change at each time point compared to baseline was determined for each variable. Statistical significance was determined by repeated measures analysis of variance. No changes were found between study and control animals in maternal BP; CO; lactate, glucose, oxygenation, or fetal HR; oxygenation, lactate, or glucose. Statistically significant differences (P < 0.01) between study and control animals were noted in ACP, Et CO2, MHR, UtBF, FBP, and Maternal/fetal pH, PCO2. All ewes delivered healthy lambs at full gestation. A CO2 pneumoperitoneum up to 15 mm Hg pressure in gravid ewes causes increased intrauterine pressure, decreased UtBF, and induces maternal and fetal acidosis. Despite these intraoperative deleterious effects, long-term fetal well being was not effected.