Intra-aortic Balloon Occlusion Research Articles

Extent of load-independence of pressure-normalized stress in swine

A load-independent index of myocardial contractility provides a measure of cardiac function. Previous contractility indices have been shown to be either load-dependent or invasive. We sought to determine the extent of load (preload and afterload)-independence of dσ*/dtmax (σ* is pressure-normalized stress) in comparison with other well-established indices. Six anaesthetized pigs underwent left ventricular pressure-volume measurements under various load conditions. The average preload was decreased by 70.0 ± 15.0% (from 39.2 ± 6.4 mL to 11.7 ± 7.7 mL) and increased by 49.3 ± 5.9% (from 35.1 ± 7.4 mL to 51.7 ± 8.9 mL). The average afterload was increased by 74.3 ± 43.5% (from 3.3 ± 0.6 mmHg/mL to 5.7 ± 1.7 mmHg/mL). When preload was reduced within an average of 21.7% (39.2 ± 6.4 mL to 30.7 ± 6.2 mL) using occlusion of the inferior vena cava, dσ*/dt max did not change significantly (6.50 ± 1.10 s⁻¹ vs 6.60 ± 0.90 s⁻¹, P = non-significant [NS]). When preload was increased within an average of 29.3% (35.1 ± 7.4 mL to 45.4 ± 7.3 mL) from infusion of normal saline, dσ*/dt max did not change significantly (7.04 ± 1.00 s⁻¹ vs 7.29 ± 1.10 s⁻¹, P = NS). When afterload was increased within an average of 42.4% (3.3 ± 0.6 mmHg/mL to 4.7 ± 1.0 mmHg/mL) using intra-aortic balloon occlusion, dσ*/dtmax did not change significantly (6.72 ± 1.18 s⁻¹ vs 6.89 ± 1.28 s⁻¹, P = NS). As expected, dσ*/dtmax was significantly increased with dobutamine. A linear regression showed no correlation between dσ*/dtmax and preload (r² = 0.02, P = 0.17) within a maximum range of -30% to +50% of preload change, or between dσ*/dtmax and afterload (r² = 0.03, P = 0.36) within maximum range of 0-100% of afterload increase, respectively. In conclusion, dσ*/dtmax is independent of loading conditions within an average of 21.7% of preload decrease, 29.3% of preload increase, 42.4% of afterload increase, and sensitive to dobutamine infusion.

Effects of Intravenous Sulfide During Porcine Aortic Occlusion-Induced Kidney Ischemia/Reperfusion Injury

In rodents, inhaled H2S and injection of H2S donors protected against kidney ischemia/reperfusion (I/R) injury. During porcine aortic occlusion, the H2S donor Na2S (sulfide) reduced energy expenditure and decreased the noradrenaline requirements needed to maintain hemodynamic targets during early reperfusion. Therefore, we tested the hypothesis whether sulfide pretreatment may also ameliorate organ function in porcine aortic occlusion-induced kidney I/R injury. Anesthetized, ventilated, and instrumented pigs randomly received either sulfide or vehicle and underwent 90 min of kidney ischemia using intraaortic balloon-occlusion, and 8 h of reperfusion. During reperfusion, noradrenaline was titrated to maintain blood pressure at baseline levels. Sulfide attenuated the fall in creatinine clearance and the rise in creatinine blood levels, whereas renal blood flow and fractional Na+ excretion were comparable. Sulfide also lowered the blood IL-6, IL-1β, and nitrite + nitrate concentrations, which coincided with reduced kidney oxidative DNA base damage and iNOS expression, and attenuated glomerular histological injury as assessed by the incidence of glomerular tubularization. While expression of heme oxygenase 1 and cleaved caspase 3 did not differ, sulfide reduced the expression Bcl-xL and increased the activation of nuclear transcription factor κB. During porcine aortic occlusion-induced kidney I/R injury, sulfide pretreatment attenuated tissue injury and organ dysfunction as a result of reduced inflammation and oxidative and nitrosative stress. The higher nuclear transcription factor κB activation was probably due to the drop in temperature.

Response to the Letter to the Editor Entitled Should Intra-Aortic Balloon Occlusion Be Used to Stop Bleeding From Severe Pelvic Fractures?

The Journal of Trauma: Injury, Infection, and Critical Care: October 2010 - Volume 69 - Issue 4 - p 1006-1007 doi: 10.1097/TA.0b013e3181f3f38a

Intra-Aortic Balloon Occlusion to Salvage Patients With Life-Threatening Hemorrhagic Shocks From Pelvic Fractures

The purpose of this study was to describe a blinded intra-aortic balloon occlusion (IABO) procedure in pelvic fractures (PF) for patients with critically uncontrollable hemorrhagic shock (CUHS). Of 2,064 patients treated for PF, 13 underwent IABO during initial resuscitation to control massive pelvic bleeding leading to CUHS. Our IABO procedure consists of internal aortic occlusion without fluoroscopy, using a latex balloon inflated in the infrarenal aorta. Retrospectively collected data included demographics, fracture classification, additional injuries, blood transfusions, surgical interventions, angiographic procedure, physiologic parameters, and survival. All balloons were successfully placed, and a significant increase in systolic blood pressure (70 mm Hg, p = 0.001) was observed immediately after IABO. Twelve of 13 patients became transferrable. Angiography performed after IABO was positive for arterial injury in 92% of patients, and 9 patients benefitted from arterial embolization. Survival rate was 46% (6 of 13) and was inversely related to the length of inflation (p = 0.026) and the mean Injury Severity Score (p = 0.011). This IABO procedure can be life saving in the management of patients with CUHS from PF, permitting transport to angiography. However, the decision for such treatment must be as quickly as possible after trauma to reduce the time of occlusion.

Esmolol and Landiolol, Selective β1-Adrenoreceptor Antagonists, Provide Neuroprotection Against Spinal Cord Ischemia and Reperfusion in Rats

Paraplegia is a devastating and unpredictable complication occasionally resulting from surgery of the thoracic and thoracoabdominal aorta. Because ultrashort-acting selective beta(1)-adrenoreceptor antagonists provide neuroprotective effects after brain ischemia, we hypothesized that they would also ameliorate spinal cord injury after transient ischemia and reperfusion in rats. Male Sprague-Dawley rats were randomly assigned to one of the following 4 groups: saline (received IV infusion of 0.9% saline at a rate of 0.5 mL/h, n = 8), esmolol (esmolol 200 microg/kg/min, n = 8), landiolol (landiolol 50 microg/kg/min), or sham surgical (n = 6). Infusion of saline or drugs was initiated 30 minutes before spinal cord ischemia and continued for the subsequent 24-hour reperfusion. Spinal cord ischemia was induced by intraaortic balloon occlusion combined with proximal arterial hypotension for 10 minutes. The spinal cord was then reperfused for 24 hours. Ischemic injury was assessed in terms of the motor deficit index score of the hindlimb and the number of viable motor nerve cells in the anterior spinal cord at 24 hours after reperfusion. The motor deficit index scores were significantly lower in the esmolol and landiolol groups compared with the saline group (P < 0.05). Histopathologic evaluation of the spinal cord showed less damage in the esmolol and landiolol groups than in the saline group (P < 0.05). These data show that ultrashort-acting selective beta(1)-adrenoreceptor antagonists can reduce neurological injury in a rat model of spinal cord ischemia-reperfusion.

Mortality After Endovascular Repair of Ruptured Abdominal Aortic Aneurysms

To document mortality after endovascular repair of ruptured abdominal aortic aneurysms (RAAAs). MEDLINE and EMBASE databases. Articles that reported data on mortality after endovascular repair of RAAAs were identified. Only patients with true ruptures were included. Additionally, information on mortality after concurrent open repair was sought. One of the authors reviewed all of the studies and extracted appropriate data. A total of 43 articles were identified, 14 of which were excluded. Twenty-nine articles with 897 patients who underwent endovascular repair met the inclusion criteria. Of the patients with available information, 86% were men; 29% had been operated on under local anesthesia; 28% were hemodynamically unstable; 17% required intra-aortic balloon occlusion; 48% received bifurcated stent grafts; 6% had endovascular procedures converted to open repair intraoperatively; and 5.5% developed abdominal compartment syndrome. In-hospital and/or 30-day mortality ranged between 0% and 54% in different series, whereas the pooled mortality after endovascular repair was 24.5% (95% confidence interval [CI], 19.8%-29.4%). In 19 studies reporting results of both endovascular and concurrent open repair from the same unit, the pooled mortality after open repair was 44.4% (95% CI, 40.0%-48.8%), and the pooled overall mortality for RAAA undergoing endovascular or open repair was 35% (95% CI, 30%-41%). Endovascular repair of RAAAs is associated with acceptable mortality rates. Additional studies will be required to verify these promising results and precisely define the role of endovascular treatment as an additional therapeutic option for RAAAs.

Sepsis Caused by Peripelvic Soft Tissue Infections in Critically Injured Patients With Multiple Injuries and Unstable Pelvic Fracture

In critically injured patients with multiple injuries and unstable pelvic fracture, late mortality almost invariably results from sepsis. We analyzed the clinical features of 11 patients with sepsis caused by soft tissue infections surrounding the fractured pelvis, of 830 patients with pelvic fracture after blunt trauma treated at our level I trauma center over the past 25 years. Soft tissue infection was defined as abscess formation in subcutaneous tissue or muscle diagnosed by computed tomography or an operation. Mean injury severity score was 48, and mean systolic blood pressure on arrival was 66 mm Hg. All patients had multiple concomitant injuries and prolonged hemorrhagic shock. Open pelvic fracture was present in five patients. Mean blood transfusion volume within 24 hours was 12,611 mL. Intra-aortic balloon occlusion was performed in three patients and transcatheter angiographic embolization in nine patients. Embolic sites of transcatheter angiographic embolization were bilateral internal iliac arteries (n = 9), lumbar artery (n = 5), median sacral artery (n = 2), and circumflex femoral artery (n = 2). Infection sites included the gluteal (n = 11), femoral (n = 6), sacral (n = 4), lumbar (n = 4), anterior iliac (n = 2), inguinal (n = 1), and perineal (n = 1) regions. Necrotic changes of infected soft tissue were found in all patients. They underwent open drainage and daily debridement with pulsatile irrigation followed by intravenous antibiotics. All patients developed severe sepsis, five of whom subsequently died of multiple organ failure. In critically injured patients with multiple injuries and unstable pelvic fracture, peripelvic soft tissue infections occasionally cause sepsis. Peripelvic infections are often accompanied by necrotic changes and easily develop into severe sepsis or multiple organ failure. Identifying high-risk patients and early diagnosis with prompt surgical treatment are indispensable for the patients' survival.

Intraaortic balloon occlusion during refractory cardiac arrest. A case report

Despite recent advances in its management, the outcome from cardiac arrest is often poor despite appropriate cardiopulmonary resuscitation (CPR). The coronary perfusion pressure (CPP) achieved during CPR is associated with successful return of spontaneous circulation (ROSC). Continuous balloon occlusion of the descending aorta is an experimental method that can occlude the ‘unnecessary’ part of the circulation, thus diverting generated pressure and blood flow to the heart and brain. We present a case report with a patient unresponsive to standard CPR in which constant intraaortic balloon occlusion achieved ROSC and successful survival.

Efeitos neuroprotetores do diltiazem em coelhos com oclusão da aorta

In the present study, we aimed to determine the protective effect of the perfusion of the distal aorta with diltiazem and ringer lactate solution on the spinal cord. Twenty-seven New Zealand rabbits were used in which spinal cord ischemia was provided by occlusion of the aorta for thirty minutes. Experimental animals were divided into four groups: group A (n=4), the sham operation group; group B (n=8) in which intraaortic balloon occlusion alone was applied; group C (n=7), ringer lactate group in which ringer lactate was perfused into distal aorta at a rate of 40 ml/kg, hr, following intraaortic balloon occlusion; group D (n=8) diltiazem group in which diltiazem 40 mg/kg, hr, in Ringer lactate was perfused into distal aorta following intraaortic balloon occlusion. Motor function of hind limbs was evaluated by Tarlov's scoring system. After observation, spinal cords were removed for histopathological evaluation. The degree of histopathological injury was well correlated with neurological function. The most severe histopathological injury and neurological dysfunction occurred in group B, followed by group C, D and A respectively. No injury or neurological dysfunction occurred in the sham group. The protective effect of diltiazem on both histopathological injury and neurological function was significant in comparison with control groups.

Intrathecal Ketorolac Pretreatment Reduced Spinal Cord Ischemic Injury in Rats

Paraplegia caused by spinal cord ischemic injury remains a potential complication of surgical repair of thoracoabdominal aortic aneurysms. Studies suggest that cyclooxygenase (COX) contributes to ischemic neuronal damage and that COX inhibitors may reduce injury. In this study, we examined whether intrathecal pretreatment with ketorolac, a nonselective COX inhibitor, had a protective effect against ischemic spinal cord injury in rats. Rats were randomized to receive either intrathecal normal saline, ketorolac 30 microg, or ketorolac 60 microg (n = 6 rats per group) 1 h before spinal cord ischemia (intraaortic balloon occlusion combined with proximal arterial hypotension for 11 min). Another 6 rats served as the sham-operated controls. Ischemic injury was assessed by hindlimb motor function and by histopathological changes in the lumbar spinal cord at 24 h after the ischemic insult. The other 20 rats (n = 10 per group) were used in the second experiments to evaluate the safety of this drug. Survival of rats was recorded 28 days after reperfusion. Intrathecal pretreatment with 60 microg of ketorolac significantly reduced neuronal death and improved hindlimb motor function, and the long-term survival was similar to that in the control group. The results suggest that intrathecal ketorolac may be of therapeutic potential for preventing spinal cord ischemic injury during thoracoabdominal aortic surgery.

Effects of Intra-Aortic Balloon Occlusion on Intestinal Perfusion, Oxygen Metabolism and Gastric Mucosal PCO2 during Experimental Hemorrhagic Shock

Background: Aortic occlusion has been suggested for the initial treatment of severe uncontrolled hemorrhagic shock. Our objective is to determine the impact of aortic occlusion, during hemorrhagic shock, on splanchnic mucosal perfusion and to correlate these findings with other systemic and regional markers of splanchnic ischemia. Methods: Fourteen dogs (17 ± 1.7 kg) anesthetized with pentobarbital were bled to a mean arterial pressure (MAP) of 40 mm Hg. After 30 min, the animals were randomly assigned to controls (no aortic occlusion, n = 7) and transfemoral aortic occlusion (TAO) at T9 level (n = 7). Superior mesenteric artery blood flow (SMABF, ultrasonic flow probe), gastric mucosal PCO₂ (gastric tonometry) and splanchnic oxygen extraction ratio (O₂ERsplanc) were evaluated for 120 min. Results:Hemorrhage caused a marked reduction in SMABF and increases in PCO₂-gap and O₂ERsplanc in both groups. TAO significantly improved MAP and further increased the PCO₂-gap and O₂ERsplanc, with a decreased SMABF. After reperfusion, SMABF, MAP and O₂ERsplanc returned to pre-occlusion values, although the PCO₂-gap remained higher in the TAO group. Conclusion: Aortic occlusion promotes blood pressure restoration with an additional insult to mucosal perfusion, which could be adequately predicted by global and/or splanchnic oxygen-derived variables during ischemia, but not during the early reperfusion period.

Effect of Intra-aortic occlusion balloon in external thoracic compressions during CPR in pigs

This study was performed to compare the effectiveness of external thoracic compressions with and without intra-aortic occlusion balloon with capnography and coronary and cerebral perfusion pressure (CPP) in the normothermic and traumatic-less cardiopulmonary arrest provoked by a ventricular fibrillation in pigs. This was an experimental study (cross-over study) in 14 pigs with similar characteristics (23 ± 2 kg, 10-12 weeks of age). After an 8-minute nonintervention period, the cardiopulmonary resuscitation (CPR) consists of 4 periods of 5 minutes alternating CPR with and without intra-aortic occlusion balloon. Main outcomes measured are end-tidal CO2 (ETCO2); intra-aortic, coronary, and cerebral perfusion pressures; blood gas analysis; and blood lactate concentration. At the end of each period, levels are obtained. Postmortem study was made. Inflation of the occlusion balloon provokes an expansion in the ETCO2 of about 38%. The coronary perfusion pressure initially goes from 10.21 to 29.0 mm Hg after the occlusion of the aorta, which means an increase of 150%. The CPP goes from 12.54 to 39.71 mm Hg after the balloon was inflated, which means an increase of 200%. In all cases the differences are statistically significant (P <.0001). These increases are less important in the final periods. Intra-aortic balloon occlusion increased ETCO2, coronary, and cerebral perfusion pressures. An early application of this technique was important. (Am J Emerg Med 2002;20:453-462. Copyright 2002, Elsevier Science (USA). All rights reserved.)

Effects of Intra-Aortic Balloon Occlusion During Cardiopulmonary Resuscitation

Copyright © by 2000 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.

Intra-aortic administration of epinephrine above aortic occlusion does not alter outcome of experimental cardiopulmonary resuscitation

Intra-aortic balloon occlusion during experimental cardiopulmonary resuscitation (CPR) improves coronary perfusion pressure and resuscitability and provides unique access to the central circulation. It has been hypothesized that administration of epinephrine into the aortic arch in combination with aortic occlusion would further improve haemodynamics during CPR, resuscitability and 24 h survival. In 16 anaesthetised dogs intravascular catheters were placed for hemodynamic and blood gas monitoring. An aortic balloon catheter was placed by femoral artery insertion with its tip just distal to the left subclavian artery. Ventricular fibrillation for 7.5 min without CPR, 2.5 min of Basic Life Support with chest compressions and ventilation with 100% oxygen were followed by 30 min of Advanced Cardiac Life Support (ACLS) with systemic canine drug dosages. The intra-aortic balloon was inflated when ACLS started and gradually deflated shortly after restoration of spontaneous circulation (ROSC). Epinephrine, in 100 μg/kg boluses every 5 min until the heart was restarted or 30 min had elapsed was administered through the intra-aortic catheter in the experimental group ( n=8) and via a central venous catheter in the control group ( n=8). Coronary perfusion pressure increased during the ACLS period in both groups ( P<0.05) with no difference between the groups and there was no difference in the frequency of ROSC (experimental group 5/8, control group 4/8). Furthermore with respect to 24 h survival, there was no difference between the experimental group (2/8) and the control group (3/8). Severe macroscopic haemorrhagic necrosis of the myocardium in the dogs with ROSC was found in 4/5 in the experimental group compared to 1/4 in the control group. In conclusion, intra-aortic administration of 100 μg/kg epinephrine doses combined with aortic occlusion during experimental CPR did not alter outcome.

Maximisation of cerebral blood flow during experimental cardiopulmonary resuscitation does not ameliorate post-resuscitation hypoperfusion

Continuous intra-aortic balloon occlusion has been reported to improve cerebral blood flow during cardiopulmonary resuscitation (CPR) but not to ameliorate the impaired blood recirculation occurring after restoration of spontaneous circulation (ROSC). Volume expansion with hypertonic solutions may improve recovery of brain function by enhancing post-resuscitation cerebral blood flow. We hypothesised that the combination of these treatments with open-chest CPR would improve cerebral blood flow during CPR, and attenuate post-resuscitation flow disturbances. In 32 anaesthetised piglets, catheters were placed for haemodynamic and blood gas monitoring. Open-chest CPR was initiated after 9 min of ventricular fibrillation. The piglets were treated either with 3 ml kg−1 hypertonic saline and dextran (HSD) (n=10), HSD and balloon occlusion (n=10) or with normal saline (n=12). After 7 min of CPR, internal defibrillatory shocks were administered to restore spontaneous circulation. Haemodynamic variables, continuous cerebral cortical blood flow, cerebral tissue pH and pCO2 and blood gas parameters were measured during CPR and up to 210 min after ROSC. Higher cerebral perfusion pressure was found in the balloon-HSD group during CPR. This group exhibited less arterial hypertension immediately after ROSC compared with the other groups. Thereafter, a fairly rapid decrease of the perfusion pressures was observed in all groups reaching a minimum level approximately 30 min after ROSC. Cerebral cortical blood flow was significantly higher and cerebral oxygen extraction ratio significantly lower in the balloon-HSD group during CPR, but not after ROSC. In conclusion, a combination of intra-aortic balloon occlusion and HSD administration improves cerebral blood flow and brain oxygen supply during experimental open-chest CPR. In contrast, cerebral blood flow after ROSC was not shown to be influenced by this treatment.

Catheter-Assisted Totally Thoracoscopic Coronary Artery Bypass Grafting: A Feasibility Study

Background. The purpose of this study is to examine the feasibility of performing totally thoracoscopic internal mammary-to-coronary artery bypass grafting with the assistance of radiologically guided catheter intervention. Methods. Fourteen dogs were subjected to mobilization of the internal mammary artery and anastomosis of it to the left anterior descending coronary artery over an angiographic catheter inserted into the internal mammary artery under fluoroscopy. The anastomosis was completed over the catheter using sutures and the application of fibrin glue. Eight animals underwent the anastomosis after their sacrifice. The other 6 animals were put on closed chest cardiopulmonary bypass and had their anastomosis done after intraaortic balloon occlusion and cardioplegic arrest of the heart. All animals had an angiographic and pathologic examination at the completion of the anastomosis. Results. Anastomosis was completed in all dogs. Three anastomoses leaked and two were noted to be stenosed at completion of the anastomosis. One leak was sealed by application of fibrin glue. Both stenotic anastomoses were caused by suturing of the back wall when a short angiographic catheter could not be positioned across the anastomosis. Conclusions. Minimally invasive totally thoracoscopic mammary-to-coronary artery bypass grafting with catheter assistance is feasible. Technical improvement and appropriate instrumentation are required to minimize anastomotic failure.

Effects of intra-aortic balloon occlusion on hemodynamics during, and survival after cardiopulmonary resuscitation in dogs.

To evaluate the effect of balloon occlusion of the proximal descending aorta during cardiopulmonary resuscitation (CPR) on hemodynamics, restoration of spontaneous circulation, and 24-hr survival. Prospective, randomized, controlled trial. Experimental laboratory in a university hospital. Eighteen anesthetized dogs. INTERVENTIONS; Catheters were placed for hemodynamic and blood gas monitoring. An aortic balloon catheter was placed with its tip just distal to the left subclavian artery. After 10 mins of ventricular fibrillation without CPR, 3 mins of Basic Life Support (chest compressions and ventilation with 100% oxygen) was followed by up to 30 mins of Advanced Cardiac Life Support with canine drug dosages. In the treatment group (n = 8), the intra-aortic balloon was inflated when Advanced Cardiac Life Support started and not deflated until shortly after restoration of spontaneous circulation. The control animals (n = 10) were treated with an identical resuscitation but without intra-aortic balloon occlusion. In the treatment group, coronary perfusion pressure was greater during Advanced Cardiac Life Support (p = .026). Restoration of spontaneous circulation was more frequent (7/8 dogs) as compared with the control group (3/10 dogs) (p = .025). There was a trend toward greater 24-hr survival in the treatment group (5/8 dogs) than in the control group (3/10 dogs). Balloon occlusion of the proximal descending aorta during experimental CPR improves restoration of spontaneous circulation. Further laboratory and human studies are needed to determine the clinical efficacy of this technique.

Improved cerebral blood flow with hypertonic saline and dextran (HSD) and intra-aortic balloon occlusion during experimental CPR

Improved cerebral blood flow with hypertonic saline and dextran (HSD) and intra-aortic balloon occlusion during experimental CPR

The influence of glycine and related compounds on spinal cord injury-induced spasticity.

Spasticity is a frequent and complex sequel to spinal cord injury. The neurochemical basis for the origin of spasticity is largely unknown. Glycine is among the most abundant neurotransmitters in the spinal cord. However, the role of glycine and related compounds in spasticity have received little attention. An ischemic spinal cord injury was created in rabbits, by an intraaortic balloon occlusion technique, which produced lower limb spasticity. A catheter was inserted into the cisterna magna and the spinal cord was bathed with 100 microM solutions of glycine, strychnine, D-serine, beta-alanine, MK-801, or artificial CSF for 4 hours at a rate of 10 microliters/min. H-reflexes were monitored before and during infusion by stimulating the posterior tibial nerve and recording from the plantar surface of the foot. Glycine, D-serine, and MK-801 depressed the H wave, strychnine produced a heightened H wave, and beta-alanine caused no significant changes. These results indicate that glycine and related compounds may influence spasticity.

Lung mechanics, gas exchange and central circulation during treatment of intra-abdominal hemorrhage with pneumatic anti-shock garment and intra-aortic balloon occlusion. An experimental study in pigs: Eur Surg Res 1994; 26/4: 240–247

Lung mechanics, gas exchange and central circulation during treatment of intra-abdominal hemorrhage with pneumatic anti-shock garment and intra-aortic balloon occlusion. An experimental study in pigs: Eur Surg Res 1994; 26/4: 240–247