Hemorheological changes caused by intermittent Pringle (Baron) maneuver in beagle canine model.

In liver resection operations the Pringle (Baron) maneuver can be used for temporary ischemia by clamping the hepatoduodenal ligament intermittently. In this beagle canine model we investigated whether hemorheological parameters may alter in systemic, portal and hepatic venous blood and in arterial samples during-after Pringle maneuvers. In Pringle Group unilateral femoral artery and external jugular vein were cannulated. From median laparotomy the hepatoduodenal ligament was exposed. The portal venous system was catheterized via a mesenteric vein and through the inferior caval vein a catheter was led to the hepatic veins. After stabilization, a 15-minute Pringle maneuver was carried out three times with 5-minute interpolated reperfusion periods. In Control Group Pringle maneuvers were not made. Before and after Pringle maneuvers parallel blood samples were taken from the cannulated vessels for determining hematological parameters and erythrocyte aggregation. Following Pringle maneuvers erythrocyte deformability, blood and plasma viscosity were also tested. The results showed that besides systemic hemorheological effects of the intermittent Pringle maneuver local leukocyte count, hematocrit and erythrocyte aggregation index altered mainly in portal venous blood, depending on the repeating number of the maneuvers. Thus, investigations of hemorheological parameters might be useful to determine the optimal duration of the Pringle maneuver.

The effects of renal ischemia-reperfusion on hemorheological factors: preventive role of allopurinol.

Changes in hemorheological parameters were studied in dogs following unilateral renal artery clamping (45-minute ischemia then reperfusion), with and without preoperative administration of allopurinol. Sham-operated animals were also evaluated. Blood samples were collected preoperatively, at beginning and at 30, 60 and 120 minutes of reperfusion, then on the 1st, 3rd, 5th and 7th days. Filtration properties of erythrocytes (relative cell transit time, RCTT), whole blood and plasma viscosity (WBV, PV), fibrinogen level and hematology parameter were determined. RCTT significantly increased for both ischemic groups at 30 minutes of reperfusion, and remained elevated on the 1st and 2nd postoperative days; these changes were abolished by allopurinol pretreatment. WBV and hematocrit increased on the 1st day, and PV and fibrinogen level showed elevation on 1st-5th postoperative days. We thus conclude that decreases of RBC deformability (i.e., higher RCTT) were characteristic and specific on early postoperative days after renal ischemia-reperfusion and that these alterations were prevented by pre-ischemia administration of allopurinol.

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

BACKGROUND: This randomized study aimed to compare the reaction of the immune system to the process of postoperative adhesion formation after open and laparoscopic cholecystectomy. METHODS: In 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. RESULTS: In 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. CONCLUSION: This randomized study proved that laparoscopic cholecystectomy was associated with less immune suppression, less inflammatory reaction, and therefore less adhesion formation than open cholecystectomy.

A new concept for esophageal resection--prevascularization: an experimental study.

We aim to elaborate upon a basically new animal model for esophageal resection. A total of 17 operations on 10 dogs were performed in order to develop a model in which resection of the cervical part of the esophagus involves two steps. The first step comprises omental flap transplantation from the abdomen to the cervical region by a microsurgical method, this omental flap improving the blood supply to the organ (prevascularization). The second step is segmental resection of the esophagus 14 days later. Of the five transplanted grafts, four still survived one week after the operation; for technical reasons, one flap had thrombotized. In the two long-term survival cases with esophageal resection after prevascularizastion, there were no major complications: the resections were successful, and the omental flap 'grew into' the tissue structure of the esophagus, assisting the healing of the anastomosis. Segmental resection of the cervical part of the esophagus was performed successfully via a new type of operation on dogs.

Systemic and regional hemorheological consequences of warm and cold hind limb ischemia-reperfusion in a canine model.

We have studied systemic and regional changes in hemorheological parameters after complete acute limb ischemia and reperfusion (I/R) in 24 mongrel dogs. Unilateral cooled and non-cooled vascular ischemia (3 h)-reperfusion (4 h), and sham-operations were performed. Blood samples were collected from the excluded region, during reperfusion and for 5 days. Whole blood and plasma viscosity (WBV, PV), relative cell transit time (RCTT) of erythrocytes, fibrinogen level and hematological parameters were determined. In I/R groups WBV of excluded blood was significantly higher compared to the base (p < 0.05), and RCTT increased during the reperfusion. On 2nd-3rd days RCTT increased significantly in both I/R groups. In each group PV and fibrinogen showed continuous increase during the postoperative period, prominently in cooled I/R group, and furthermore WBV corrected for hematocrit (40%) was the highest in cooled I/R group. These suggest that surgical acute limb I/R may cause hemorheological changes, which are more serious after cooling. (Grants: OTKA-T032571, 6003/1/2001/ETT.)

Operation technique and healing process of telescopic ileocolostomy in dogs.

The healing process of telescopic anastomoses was found in an animal experiment with 12 mongrel dogs. After the division of vessels an ileal segment of different length was invaginated into the lumen of the colon using single-layer interrupted sutures. The following four groups were used: Group A (n = 3): end-to-side ileocolostomy, single-layer interrupted suture (invagination length: 0 mm), survival time: 21 days. Group B (n = 3): invagination length: 20 mm, survival time: 7 days. Group C (n = 3): invagination length: 10 mm, survival time: 21 days. Group D (n = 3): invagination length: 20 mm, survival time: 21 days. At the end of the above survival times the anastomosis area was removed. The bursting pressure was measured and morphological as well as histological examinations were performed. In each case the 0-day look-alikes of anastomoses were performed using the remnant bowels, and bursting pressure measurements were done on these models as well. Anastomosis leakage did not occur. The serosal layer of the intracolonic part of the ileum disappeared during the healing process. The free surface of the intracolonic ileal segment became covered by the sliding mucosa of the colon and the prolapsing mucosa of the ileum. The following could be concluded after the experiments: The inner pressure tolerance of a telescopic ileocolostomy promptly after preparation is better than in case of another single-layer anastomosis. This fact results in increased safety against leakage on the first postoperative days. The inner pressure tolerance of the telescopic ileocolostomy increases during the healing process and it does not depend on the length of the invaginated part (0 day-20 mm: 56 mmHg +/- 6, Group A: 252 +/- 39, Group B: 154 +/- 19, Group C: 249 +/- 20, Group D: 298 +/- 2). There is no difference in pressure tolerance between the telescopic and the end-to-side single-layer interrupted anastomoses after the healing process. The invaginated section within the lumen of the large intestine does not suffer ischaemic or any other kind of damage. This inexpensive and simple anastomosis technique could be useful in the veterinary surgical practice as well.

Experimental examination of the healing process of telescopic esophageal anastomosis.

The basis of telescopic anastomosis is old, only the practical details of it have changed and improved. The telescopic anastomosis technique is successfully applied in our practice for reconstruction of gastrectomy and esophageal resection. The reason for this study was that data about the healing process of telescopic anastomosis had not been found in the literature. We used four groups of mongrel dogs for our experiments: Group A (n = 3) received 20 mm-long invaginations with a survival time of 7 days; Group B (n = 3) received 10 mm-long invaginations with a survival time of 21 days; Group C (n = 3) received 20 mm-long invaginations with a survival time of 21 days; Group D (n = 3) received 30 mm-long invaginations with a survival time of 21 days. At the end of the above survival times we removed the anastomosing area, measured the bursting pressures and performed morphological and histological examinations. In each case we also performed an anastomosis exactly the same as a completely healed anastomosis and its pressure tolerance was measured (0 day). The pressure tolerance within the anastomosis rises gradually and independently of the length of the invaginated esophageal part. Anastomosis leakage did not occur. The invaginated esophageal part did not suffer any damage. The muscular wall of the intragastric part of the esophagus became covered by the mucosa of the stomach during the healing process and it joined with the esophageal mucosa at the edge of the free end of the esophagus.

[Data about the early physical reliability of hand-sewn anastomoses in esophagectomy and gastrectomy]. / Adatok a nyelócsó és a gyomor reszekciós mútéteinél kézzel varrt anasztomózisok korai fizikai varratbiztonságához.

We examined on models the inner pressure tolerance of the most frequently performed single layer anastomoses used in esophagectomies and gastrectomies. The aim was to examine whether interrupted or continuous suture proves safer immediately after the operation. We investigated the difference between sutures involving and not involving the mucosa. The anastomosis models were of organs of hybrid pigs slaughtered in the meet-industry. Atraumatic, 3/0 Biosyn suture material was used. The bursting pressure was measured by insufflating CO2 gas. Its bursting pressure can characterize the inner pressure tolerance of an anastomosis. The circumstances of the experiment, the suture technique and the examination of the bursting pressure were standardized. Our considerations are: 1. The early inner pressure tolerance of an anastomosis does not depend on the condition of the wall. The critical factor is their ability to expand. 2. The inner pressure tolerance of continuous sutures is better than of interrupted ones if the tissues in the suture line show similar degree of dilatation. Optimal conditions are achieved with end-to-end or side-to-side anastomoses of single organs (for example between small bowel and small bowel or colon and colon). 3. Involving the mucosa in the stitches has not influenced early physical suture certainty.

[Experimental model for the examination of inner pressure tolerance of telescopic anastomosis and other frequently performed anastomosis types of the esophagus]. / Nyelócsóvel készült süllyesztett és más gyakrabban alkalmazott anasztomózis változatok belsó nyomástúrésének vizsgálata modellkísérletekben.

We have good results with telescopic anastomosis technique in partial oesophagectomies and gastrectomies. As we could not find data about the healing process of telescopic anastomoses so we started experimenting. Inside pressure tolerance was examined immediately after performing anastomoses by measuring the bursting pressure using the organs of pigs slaughtered in the meat industry. Both oesophago-gastrostomies and oesophago-jejunostomies were performed with telescopic, single layer interrupted, single layer continuous, double layer interrupted and double layer continuous-interrupted technique, 9 of each anastomosis. A series of oesophago-jejunostomies were performed with EEA stapler. 99 anastomoses of 11 types were investigated. We found, that the inner pressure tolerance of telescopic oesophago-gastrostomy is better than any other single layer type variant. On the other hand the double layer type variants have much better pressure tolerance than the telescopic and other two type single layer anastomoses. The difference is statistically significant. In oesophago-jejunostomies the pressure tolerance of telescopic anastomosis is better than of the single layer interrupted type but the difference between the telescopic and single layer continuous type anastomoses is not significant. The pressure tolerance of double layer anastomosis is higher than the telescopic one but the difference is significant only in the continuous-interrupted type. The inner pressure tolerance of telescopic and EEA stapler anastomoses are equal. The investigation of additional features in anastomosis healing is in progress.

Basic teaching in microsurgery.

We summarize our 15 years of educational experience in the field of teaching microsurgery. The students can be divided into three groups: (1) medical students, (2) researchers, (3) medical doctors and specialists. Characteristics of our method include the following: activity, synchronism, video-assistance, self-controlling, individualization, analysis. The Furka microsurgical educational method, named after one of the authors, is 20 hours long (five 4-hour sessions). The first lesson allows students to become acquainted with the microsurgical instruments. The next lesson consists of learning the probe of layer-feeling. The third lesson is to learn how to produce stitches under the microscope. The fourth lesson includes arterial anastomosis preparation on fresh arterial pieces of animal origin. The fifth lesson means a quality change from previous classes, as practice is performed on living animals, generally rats. The teaching of microsurgical basics requires both patience and empathy. The teaching process is most successful if one teacher deals with a maximum of two students.

Spleen autotransplantation in mice: a novel experimental model for immunology study.

The aim of the experimental model to develop a spleen transplant model in mice to study the role of spleen in autoimmune and transplant rejection. After a midline incision, splenectomy was performed. Four tiny segments were cut from the removed spleen and were rinsed at room temperature in physiological salt solution. The greater omentum was lifted and four omental pockets were created; four thin segments were then placed into the "nests," subsequently marked, and fixed using 8-0 suture. The abdomen was then closed. The duration of the survival time was different among the nine groups (n = 3-3). Tissue samples were taken from the marked areas for histological examination stained with hematoxylin and eosin (H&E). H&E staining demonstrated large, well-circumscribed splenic nests with lymphoid zone and red pulp and well-formed trabecules in the spleen. Among the possible applications of this novel model is the ability to study the role of spleen in autoimmune and organ rejection.

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

BACKGROUND: The aim of this study was to evaluate the extent of postoperative adhesion formation after laparoscopic and open cholecystectomy. MATERIALS AND METHODS: Qualified 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. RESULTS: No 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). CONCLUSIONS: It 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.

[How do intraoperative complications effect adhesion formation after laparoscopic cholecystectomy: a comparative animal study]. / Az intraoperatív szövódmények hatása a posztoperatív hasúri adhesiók kialakulására laparoszkópos cholecystectomiát követóen: összehasonlító állatkísérlet.

BACKGROUND: The aim of this study was to evaluate the extent of postoperative formation of adhesions following laparoscopic and open cholecystectomy. MATERIAL AND METHODS: 60 experimental laparoscopic cholecystectomies (LC) were performed in dogs by qualified surgeons to learn laparoscopic technique. To assess the relationship between complications occurred during the operation (bleeding, laceration of the liver bed or gallbladder perforation) and the formation of adhesions surviving animals were divided into 4 groups according to the type of complication. We assessed the results during second-look laparoscopy 4 weeks following LC using the adhesion index (AI: 0-4 score). Animals were then sacrificed to measure the extent of adhesions. As a control group open cholecystectomy was performed in 15 dogs without intraoperative complications. Mann-Whitney Rank Sum test and Dunn's Method were used for statistical analysis. RESULTS: No adhesions were observed in the laparoscopic group without intraoperative complications. In all dogs with bleeding or laceration of the liver bed maintained by electrocoagulation, adhesions developed. Formation of adhesion in these groups was significantly higher than in "ideal LC" or in case of gallbladder perforation (P < 0.01). All animals in the control group developed significantly more adhesions compared to the experimental group (p < 0.05). CONCLUSION: LC produces less adhesion compared to conventional open technique. Complications such as bleeding or laceration of the liver bed during LC can increase the formation of adhesions. No formation of adhesions can be related to gallbladder perforation during LC.

The judgement of adhesion formation following laparoscopic and conventional cholecystectomy in an animal model.

INTRODUCTION: The development of postoperative adhesions remains an almost inevitable consequence of visceral and gynaecologic surgery, appearing in 50-95% of all patients. Although decreased adhesion formation is one of the accepted advantages of laparoscopic surgery, only a small number of prospective studies have been done to support this claim. AIMS OF THE STUDY: To evaluate the extent of postoperative adhesion formation after laparoscopic and open cholecystectomy. MATERIAL AND METHOD: 60 experimental laparoscopic cholecystectomies (LC) were performed by qualified surgeons in dogs with the aim to acquire the laparoscopic technique. To assess the relation between the complications during the operation (bleeding, injury to the liver substance or gallbladder perforation) and the formation of adhesions, the surviving animals were divided into 4 groups according to the complications occurred. The assessment of the results was made by second--look laparoscopy 4 weeks following LC using the adhesion index. As a control group open cholecystectomy was then performed in 5 dogs without intraoperative complications. RESULTS: No adhesion formation was observed in the groups where no intraoperative complications occurred. In all the cases where bleeding or injury to the liver bed occurred adhesion formation occurred. No adhesion formation was observed in case of gallbladder perforation. In all the animals of the control group adhesion formation was observed. CONCLUSION: It seems that LC has a reduced rate of adhesion formation when compared with the open technique. Complications such as bleeding or injury to the liver substance during LC can enhance adhesion formation. No adhesion formation can be mentioned in relation with gallbladder perforation when the laparoscopic technique is applied.

Minimally invasive laparoscopic surgery on experimental animal models.

Our goal was to find a very good model for gynecological laparoscopic operations. The main purpose of the operations was to perform the same types of laparoscopic operations as we use daily in our clinical practice at the Department of Obstetrics and Gynecology. UMSD. The uterus of female dogs seemed to be ideal for this work. In every experiment we carried out 10 different interventions on identical part of different dog uterus. The operations were performed at identical time period of day (a.m.). The weight of the female dogs were similar. The anaesthesia was also performed the same way in every case. The main purpose of the operations was to find some significant changes or differences between the 10 different surgical techniques. The hystological investigation were carried out with normal microscope and electron microscope.