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Anesthetized Pigs (anesthetized + pig)
Selected AbstractsVisualization of alveolar recruitment in a porcine model of unilateral lung lavage using 3He-MRIACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009A. RUDOLPH Background: In the acute respiratory distress syndrome potentially recruitable lung volume is currently discussed. 3He-magnetic resonance imaging (3He-MRI) offers the possibility to visualize alveolar recruitment directly. Methods: With the approval of the state animal care committee, unilateral lung damage was induced in seven anesthetized pigs by saline lavage of the right lungs. The left lung served as an intraindividual control (healthy lung). Unilateral lung damage was confirmed by conventional proton MRI and spiral-CT scanning. The total aerated lung volume was determined both at a positive end-expiratory pressure (PEEP) of 0 and 10 mbar from three-dimensionally reconstructed 3He images, both for healthy and damaged lungs. The fractional increase of aerated volume in damaged and healthy lungs, followed by a PEEP increase from 0 to 10 mbar, was compared. Results: Aerated gas space was visualized with a high spatial resolution in the three-dimensionally reconstructed 3He-MR images, and aeration defects in the lavaged lung matched the regional distribution of atelectasis in proton MRI. After recruitment and PEEP increase, the aerated volume increased significantly both in healthy lungs from 415 ml [270,445] (median [min,max]) to 481 ml [347,523] and in lavaged lungs from 264 ml [71,424] to 424 ml [129,520]. The fractional increase in lavaged lungs was significantly larger than that in healthy lungs (healthy: 17% [11,38] vs. lavage: 42% [14,90] (P=0.031). Conclusion: The 3He-MRI signal might offer an experimental approach to discriminate atelectatic vs. poor aerated lung areas in a lung damage animal model. Our results confirm the presence of potential recruitable lung volume by either alveolar collapse or alveolar flooding, in accordance with previous reports by computed tomography. [source] Metabolic responses in ischemic myocardium after inhalation of carbon monoxideACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2009K. AHLSTRÖM Background: To clarify the mechanisms of carbon monoxide (CO) tissue-protective effects, we studied energy metabolism in an animal model of acute coronary occlusion and pre-treatment with CO. Methods: In anesthetized pigs, a coronary snare and microdialysis probes were placed. CO (carboxyhemoglobin 5%) was inhaled for 200 min in test animals, followed by 40 min of coronary occlusion. Microdialysate was analyzed for lactate and glucose, and myocardial tissue samples were analyzed for adenosine tri-phosphate, adenosine di-phosphate, and adenosine mono-phosphate. Results: Lactate during coronary occlusion was approximately half as high in CO pre-treated animals and glucose levels decreased to a much lesser degree during ischemia. Energy charge was no different between groups. Conclusions: CO in the low-doses tested in this model results in a more favorable energy metabolic condition in that glycolysis is decreased in spite of maintained energy charge. Further work is warranted to clarify the possible mechanistic role of energy metabolism for CO protection. [source] Transatrial Access to the Normal Pericardial Space For Local Cardiac Therapy: Preclinical Safety Testing with Aspirin and Pulmonary Artery HypertensionJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 5 2001TODD C. PULERWITZ M.D. The reliability, rapidity, and safety of nonsurgical, transatrial pericardial access for local cardiac therapy have been demonstrated in healthy animals. Since many patients take aspirin or have increased right-sided pressures, we evaluated the procedure's safety under these conditions. Transatrial pericardial access was performed in anesthetized pigs following aspirin administration (162 mg po, n = 6) or during experimental pulmonary artery hypertension (n = 4 different animals) and required only 3 minutes following guide catheter positioning. Platelet aggregability testing with arachidonic acid confirmed aspirin effectiveness. Mean pericardial fluid hematocrit was 0.1 ± 0.1% after 2 days of aspirin therapy and 1.9 ± 1.1% at sacrifice 24 hours later (NS). Mean pericardial fluid hematocrit was 1.0 ± 0.5% after 45 minutes of pulmonary artery hypertension and 4.3 ± 0.8% at sacrifice 30 minutes later (NS). Histologic analysis in both groups revealed a small thrombus and localized inflammation at the site of puncture. Neither aspirin use nor pulmonary artery hypertension causes significant bleeding into the pericardial space following transatrial access and thus does not preclude this route for local cardiac drug delivery. [source] Decreased portal flow volume increases the area of necrosis caused by radio frequency ablation in pigsLIVER INTERNATIONAL, Issue 3 2007Tsuyoshi Yoshimoto Abstract Background/aims: Although radio frequency ablation (RFA) has been widely accepted as an effective treatment for hepatocellular carcinoma (HCC), severe complications are not uncommon. Major complications seem to occur as a result of over-ablation beyond the intended area. As most patients with HCC have underlying cirrhosis, we speculated that decreased portal flow might cause the necrosis associated with RFA. To confirm this hypothesis, we examined the area of necrosis resulting from RFA under varying conditions of portal flow in a porcine model. Methods: RFA was performed using ultrasonographic guidance in anesthetized pigs. During the RFA procedure, portal flow was regulated by a balloon catheter, which was set in a portal trunk. The necrosis area was measured after sacrifice and was compared with the hyperechoic area that appeared during ablation. In another session, RFA was performed close to the hepatic vein and endothelial damage was examined. Results: The necrosis area caused by RFA was significantly larger when the portal flow volume was decreased by 50% or more. The hyperechoic lesion was always larger than the area of pathological necrosis regardless of portal flow volume. Under conditions of decreased portal flow, the vessel endothelium near the ablated area was more readily damaged. Conclusion: Decreased portal flow volume resulted in enlargement of the area of necrosis caused by RFA. Our results indicate that over-ablation could easily occur in patients with advanced cirrhosis, and that this could lead to major complications. Ultrasonographic guidance may be helpful for avoiding over-ablation. [source] New probe for the measurement of dynamic changes in the rectumNEUROGASTROENTEROLOGY & MOTILITY, Issue 1 2004I. S. Andersen Abstract, Conventional mano-volumetric techniques cannot measure changes in circumferential dimensions at several axial positions within a bowel segment. Our aims were to validate a new impedance planimetry probe for simultaneously measuring the cross-sectional area (CSA) at five axial positions in vitro and in vivo in 10 anesthetized pigs. The day-to-day coefficient of variation (CV) for CSA measured by the probe in cylindrical tubes of known diameter was 0.8,9.5%. The mean from actual diameter deviation ranged from 2.3 to 6.7%. In a conical tube the day-to-day CV was 2.3,8% and mean percentage deviation ,2.8 to 1.0. Interposed narrowing sections caused a total CV of 7,13%. In vivo studies revealed variations in CSA, associated with expulsion of flatus. It is concluded that impedance planimetry allows simultaneous measurement of CSA at several levels within the rectum. In vitro validity was acceptable and alterations in lumen diameter were identified in vivo. [source] Challenges Facing Validation of Noninvasive Electrical Imaging of the HeartANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2005Martyn P. Nash Ph.D. Noninvasive imaging of regional cardiac electrophysiology remains an elusive target. Such imaging is still in its infancy, particularly in comparison to structural imaging modalities such as magnetic resonance imaging (MRI), x-ray computed tomography (CT), and ultrasound. We present an overview of noninvasive ECG imaging, and the challenges and successes of the various techniques across a range of applications. Unlike MRI and CT, reconstructing cardiac electrophysiology from remote body surface measurements is a highly ill-posed problem. We therefore first review the theoretical considerations and associated algorithms that are used to address this issue. We then focus on the important issue of validation, and review and contrast recent advances in this area. Efforts to validate ECG inverse procedures using a modeling-based approach are addressed first. We then discuss various experimental studies that have been conducted to provide appropriate data for robust validations. We present new data that are simultaneously recorded from dense arrays of electrodes on the epicardium and body surface of anesthetized pigs during sinus rhythm, ventricular pacing, and regional ischemia. These data have been obtained specifically to help validate inverse ECG procedures, and form a useful supplement to recent clinical validation studies. Finally, clinical applications and outstanding issues regarding noninvasive imaging of regional cardiac electrophysiology are addressed. [source] Effect of Hemodiafiltration on Pulmonary Hemodynamics in Endotoxic ShockARTIFICIAL ORGANS, Issue 12 2003B. Lambermont Abstract:, Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary hemodynamics during septic shock. In the Endo group, six anesthetized pigs received a 0.5 mg/kg endotoxin infusion over 30 min. In the HDF group (n = 6), HDF was started 30 min after the end of the endotoxin infusion, while in the Control group (n = 4) they received HDF but no endotoxin infusion. Pulmonary hemodynamics were analyzed in detail with a four-element windkessel model. Although in the Control group, HDF did not alter pulmonary hemodynamic parameters, in the HDF group, it was responsible for an amplification of the deleterious pulmonary vascular response to endotoxin insult. Our results show that HDF must be used cautiously in septic shock since it can precipitate right heart failure by increasing pulmonary vascular resistance. [source] Teaching gross anatomy using living tissueCLINICAL ANATOMY, Issue 2 2002D.S. Hubbell Abstract Embalmed cadaver tissues and organs that are dissected in gross anatomy laboratories lack many characteristics of fresh or living tissues. The purpose of this study was to assess the educational value of allowing first-year medical students to experience first-hand the color, texture, delicacy and other qualities of living porcine tissues and organs that are similar to those of human tissues. Guided by a laboratory protocol, medical students palpated and inspected organs of the opened thorax, abdomen and pelvis of anesthetized pigs on pulmonary ventilators. The learning experience was rated highly by the students as well as by the participating faculty. A further review of the medical students' later experiences at autopsies and in surgical clerkships showed that the living-tissue experience in their gross anatomy course represented a large part of their medical school exposure to unembalmed tissues. Clin. Anat. 15:157,159, 2002. © 2002 Wiley-Liss, Inc. [source] | ||||||||||