I. Furka

The influence of intraoperative complications on adhesion formation during laparoscopic and conventional cholecystectomy in an animal model

BackgroundThe aim of this study was to evaluate the extent of postoperative adhesion formation after laparoscopic and open cholecystectomy.Materials and methodsQualified surgeons performed 60 experimental laparoscopic cholecystectomies (LC) in dogs with the aim to acquire the laparoscopic technique. To assess the relation between the complications during the operation (bleeding, laceration of the liver bed, or gallbladder perforation) and the formation of adhesions, surviving animals were divided into four groups according to the type of complication occurred. Assessment of the results was made by second-look laparoscopy 4 weeks after LC using the adhesion index (AI; score range, 0–4). The animals then were killed so the extent of adhesion formation could be measured. As a control, open cholecystectomy was performed in 15 dogs without intraoperative complications. The Mann-Whitney rank-sum test and Dunn’s method were used for statistical analysis.ResultsNo adhesion formation or intraoperative complications were registered in the laparoscopic group I. In all the cases wherein bleeding or laceration of the liver bed occurred and was managed with electrocoagulation, adhesions formed. Adhesion formation in these groups was significantly higher than in “ideal LC” or cases of gallbladder perforation alone (p<0.01). All the animals in the control group developed significantly more adhesions than those in the experimental group (p<0.05).ConclusionsIt seems that LC has a lower rate of adhesion formation than the conventional open technique. Complications such as bleeding or laceration of the liver bed during LC can enhance adhesion formation. No adhesion formation can be mentioned in relation to gallbladder perforation during LC.

Allopurinol Prevents Erythrocyte Deformability Impairing but Not the Hematological Alterations After Limb Ischemia–Reperfusion in Rats

The measurement of red blood cell deformability provides a possible method for detecting the effect of ischemia–reperfusion on erythrocytes. In our study the effect of 1-h ischemia–reperfusion with or without allopurinol pretreatment on hematological parameters and red blood cell deformability was investigated in a follow-up experiment of 26 male CD outbred rats that were subjected to unilateral hind-limb ischemia by microvascular clips on femoral vessels for 1 h (IR, n = 6), some rats received allopurinol pretreatment under the same conditions (50 mg/kg, AP + IR, n = 8), others were subjected to sham operation (n = 6), and the rest of animals served as control (n = 6). Measurement of erythrocyte deformability using a bulk filtrometer with special setting of cell suspension hematocrit (1%), and determination of hematological parameters were performed daily for one week. In the IR group, relative cell transit time increased significantly on postoperative days 1 and 2, which was not observed in the other groups. Settings for the measurement of erythrocyte deformability by reducing the blood sample volume gave the possibility of monitoring the resulting changes in rats. Mean corpuscular volume and hemoglobin, platelet count, and platelet volume were higher in the IR and AP + IR groups than in the other groups. In summary, short-term ischemia and reperfusion induced lower red blood cell deformability in the early postoperative period, which could be prevented by allopurinol pretreatment.

Hemorheological changes in ischemia-reperfusion: An overview on our experimental surgical data

Blood vessel occlusions of various origin, depending on the duration and extension, result in tissue damage, causing ischemic or ischemia-reperfusion injuries. Necessary surgical clamping of vessels in vascular-, gastrointestinal or parenchymal organ surgery, flap preparation-transplantation in reconstructive surgery, as well as traumatological vascular occlusions, all present special aspects. Ischemia and reperfusion have effects on hemorheological state by numerous ways: besides the local metabolic and micro-environmental changes, by hemodynamic alterations, free-radical and inflammatory pathways, acute phase reactions and coagulation changes. These processes may be harmful for red blood cells, impairing their deformability and influencing their aggregation behavior. However, there are still many unsolved or non-completely answered questions on relation of hemorheology and ischemia-reperfusion. How do various organ (liver, kidney, small intestine) or limb ischemic-reperfusionic processes of different duration and temperature affect the hemorheological factors? What is the expected magnitude and dynamics of these alterations? Where is the border of irreversibility? How can hemorheological investigations be applied to experimental models using laboratory animals in respect of inter-species differences? This paper gives a summary on some of our research data on organ/tissue ischemia-reperfusion, hemorheology and microcirculation, related to surgical research and experimental microsurgery.

Hemorheological, morphological, and oxidative changes during ischemia-reperfusion of latissimus dorsi muscle flaps in a canine model

Although ischemia‐reperfusion (I/R) strongly influences muscle flap survival in reconstructive surgery, there is limited knowledge about its relation to hemorheological parameters and oxidative stress markers in flaps. In the present study we investigated these changes during I/R of latissimus dorsi muscle (LDM) flaps in beagle dogs. In four animals LDM flaps were prepared bilaterally. The right side served as control, while the left sides vascular pedicle was clamped for 60 minutes, and a 60‐minute reperfusion was allowed afterward. Blood samples (0.5 ml each) were taken from the pedicles vein bilaterally before and after the ischemia, and at the 5th, 15th, 30th, 45th, and 60th minutes of the reperfusion, for hematological and erythrocyte aggregation tests. In muscle biopsies, taken before and after I/R, histological investigations and tests for measuring gluthation‐peroxidase (GSH‐PX) activity, glutathione (GSH) and carbonyl concentrations, and thiobarbituric acid reactive substances (TBARS) content were carried out. In I/R side leukocyte count increased during the reperfusion with a peak at the 30th minute. Hematocrit continuously increased from the 15th minute. In the first 5 minutes of the reperfusion, erythrocyte aggregation increased, than tented to be normalized. In muscle homogenates GSH‐PX activity did not change markedly, GSH content slightly decreased, carbonyl and TBARS content increased during reperfusion. A 1‐hour ischemia and reperfusion of LDM flaps caused local changes of leukocyte distribution and erythrocyte aggregation, supposedly due to the metabolic and inflammatory reactions. Oxidative damage during reperfusion was also demonstrated.

Urethral replacement with autologous venous graft: An experimental study in the dog

SummaryThis study investigated the experimental replacement of the urethra with autologous vein grafts. A free transplant of external jugular vein segments were used to replace a resected urethral segment in dogs. We suggest that replacement of the urethra with autologous fraft could be applicable in the reconstructive surgery of the urethra.

Adhesion formation with open versus laparoscopic cholecystectomy: an immunologic and histologic study.

BackgroundThis randomized study aimed to compare the reaction of the immune system to the process of postoperative adhesion formation after open and laparoscopic cholecystectomy.MethodsIn this study, 20 mongrel dogs were used: 10 each in the laparoscopic and open cholecystectomy groups. Blood and peritoneal lavage samples were taken up to postoperative day 14, followed by second-look laparoscopy and reoperation to detect the rate of adhesion formation. Also, specimens were obtained from the liver bed for histology.ResultsIn the open cholecystectomy group, the white blood cell count was higher in blood samples and lower in lavage specimens. Adhesion formation was extensive, and the histologic immune reaction was more intensive in the open cholecystectomy group.ConclusionThis randomized study proved that laparoscopic cholecystectomy was associated with less immune suppression, less inflammatory reaction, and therefore less adhesion formation than open cholecystectomy.

Effect of Omental Angiogenic Lipid Factor on Revascularization of Autotransplanted Spleen in Dogs

Since the turn of the century, studies have been carried out showing that the omentum contains a factor which enhances revascularization of ischemic tissues. This study was conducted for a period of 3 months and was designed to evaluate the effect of an omental lipid fraction on neovascularization of autotransplanted spleen chips in dogs. Twelve dogs underwent splenectomy and autotransplantation of 5 splenic chips into an omental pouch. In 4 dogs, the splenic chips were immersed in omental angiogenic lipid factor (OAF), while on another 4 dogs, an intramuscular injection of 4 cm3 of OAF was given each day for 7 days postoperatively. A further 4 dogs were not given any of the above treatments (control group). Serial angiographies and histologic examinations demonstrated better neovascularization and regeneration of the transplanted spleen in the dogs from the immersion plus injection group. These data suggest that the omental lipid fraction contains a factor which induces a better regeneration of splenic transplants.

Concerning the importance of changes in hemorheological parameters caused by acid-base and blood gas alterations in experimental surgical models

Acid-base equilibrium and pH of blood have important clinical consequences in numerous diseases and pathophysiological conditions. The micro-rheological parameters of blood, such as red blood cell deformability and red blood cell aggregation are influenced by several metabolic factors, and provide information regarding inflammatory, septic and tissue or organ ischemia-reperfusion processes. Despite the anticipated logical relation of the blood acid-base condition, blood gas parameters and pH to red blood cell deformability and aggregation, controversial data can be found in the literature. Furthermore, related to ischemia-reperfusion hemorheological studies little is known about this issue. In this paper we aimed to thought-provokingly overview some aspect of acid-base changes, blood pH and hemorheological parameters, discussing certain results from ischemia-reperfusion experimental surgical models (local versus systemic changes), laboratory technical and experimental design protocols related to in vitro and in vivo studies.

Changes of local and systemic hemorheological properties in intestinal ischemia‐reperfusion injury in the rat model

The aim of this study was to investigate intestinal ischemia‐reperfusion and its local and systemic hemorheological relations in the rat. Ten anaesthetized female CD outbred rats were equally divided into 2 experimental groups. (1) Ischemia‐reperfusion (I/R): the superior mesenterial artery was clipped for 30 minutes. After removing the clip, 60 minutes of the reperfusion was observed before extermination. Blood samples were taken from the caudal caval vein and from the portal vein before ischemia, 1 minute before and after clip removal, and at the 15th, 30th, and 60th minutes of the reperfusion. (2) Sham operation: median laparotomy and blood sampling were done according to the timing as in I/R group. Hematological parameters, red blood cell aggregation, and deformability were determined. Leukocyte count and mean volume of erythrocytes increased slightly but continuously in portal venous samples during the reperfusion period. Red blood cell aggregation values were higher in portal blood by the end of ischemia, and then became elevated further comparing to the caval venous blood. Both in caval and portal venous samples of I/R group red blood cell deformability significantly worsened during the experimental period compared to its base and Sham group. In portal blood red blood cell deformability was impaired more than in caval vein samples. Histology showed denuded villi, dilated capillaries, and the inflammatory cells were increased after a 30 minutes ischemia. In conclusion, intestinal ischemia‐reperfusion causes changes in erythrocyte deformability and aggregation, showing local versus systemic differences in venous blood during the first hour of reperfusion.

Simultaneous Continuous Measurement of pO2, pCO2, pH and Temperature in Brain Tissue and Sagittal Sinus in a Porcine Model

INTRODUCTION The clinical use of brain tissue oxygen measurement in patients with severe head injury is increasing. It is important to compare the findings in brain tissue with cerebrovenous blood oximetry, to obtain normal values and to find out limitations of the method. We evaluated a newly available multisensor probe simultaneously in the brain tissue and in the sagittal sinus in a porcine animal model. METHODS We placed the Paratrend 7-probe (BSL, High Wycombe, UK) in the left frontoparietal white matter and measured pO2 (PtiO2), pCO2 (ptiCO2), pH and temperature while simultaneously measuring these parameters (pcvO2, pcvCO2) in the sagittal sinus in 7 pigs under general anaesthesia during oxygen enhancement. RESULTS The relation between oxygen increase in brain tissue and in the sagittal sinus showed a coefficient of correlation (CCmean) rmean = 0.96. The quantitative response in brain tissue was much more sensitive than in the sinus. A close correlation between pCO2 in brain tissue and sagittal sinus and the increase of the inspired oxygen was seen: CC ptiCO2 to arterial oxygen pressure (paO2) - rmean = 0.67, CC pcvCO2 to paO2 - rmean = 0.88. CONCLUSIONS Measuring partial oxygen pressure in brain tissue is more responsive to physiological variations, and the absolute values are more sensitive than oxygen measurement in the cerebrovenous compartment. This is important for interpreting measured values and introducing new coefficients for patient monitoring.