Heparin-like effect of a dual antiplatelet and anticoagulant (APAC) agent on red blood cell deformability and aggregation in an experimental model.

Treatments with different antithrombotic agents can affect micro-rheological variables, such as red blood cell (RBC) deformability and aggregation. Since the effect of dual antiplatelet and anticoagulant (APAC) treatment on micro-rheology is unknown, we aimed to investigate the effect of different intravenous doses of APAC on hematological and micro-rheological variables in a porcine model. Two groups were formed (APAC group, Control group), and blood was collected from the animals at preset intervals. Hematological variables, RBC deformability, and aggregation were measured. We observed an improvement in the RBC deformability measured at a low shear stress range (< 3 Pa). However, after both doses, a decrease in the maximal elongation index of RBC values occurred in the APAC group. RBC aggregation increased after APAC bolus dose, while it gradually and dose-dependently decreased. Supposedly, the improvement in RBC deformability that was observed at a lower shear rate could facilitate aggregation. Administration of APAC and unfractionated heparin (UFH) caused comparable changes in hematological and hemorheological variables. Signs of thrombosis or bleeding did not occur. APAC and UFH had comparable micro-rheological effects.

Changes in microcirculation of small intestine end-to-end anastomoses in an experimental model.

INTRODUCTION: Sufficient perfusion is essential for a safe intestinal anastomosis. Impaired microcirculation may lead to increased bacterial translocation and anastomosis insufficiency. Thus, it is important to estimate well the optimal distance of the anastomosis line from the last mesenterial vessel. However, it is still empiric. In this experiment the aim was to investigate the intestinal microcirculation at various distances from the anastomosis in a pig model. MATERIALS AND METHODS: On 8 anesthetized pigs paramedian laparotomy and end-to-end jejuno-jejunostomy were performed. Using Cytocam-IDF camera, microcirculatory recordings were taken before surgery at the planned suture line, and 1 to 3 mesenterial vessel mural trunk distance from it, and at the same sites 15 and 120 min after anastomosis completion. After the microcirculation monitoring, anastomosed and intact bowel segments were removed to test tensile strength. RESULTS: The proportion and the density of the perfused vessels decreased significantly after anastomosis completion. The perfusion rate increased gradually distal from the anastomosis, and after 120 min these values seemed to be normalized. Anastomosed bowels had significantly lower maximal tensile strength and higher slope of tensile strength curves than intact controls. CONCLUSION: Alterations in microcirculation and tensile strength were observed. After completing the anastomosis, the improvement in perfusion increased gradually away from the wound edge. The IDF device was useful to monitor intestinal microcirculation providing data to estimate better the optimal distance of the anastomosis from the last order mesenteric vessel.

Local and Systemic Micro-Rheological Changes during Intestinal Anastomosis Operation: A Metabolic Dependence in an Experimental Model.

Hemorheological factors may show arterio-venous differences. Alterations in acid-base and metabolic parameters may also influence these factors. However, little is known about changes in micro-rheological parameters during abdominal surgery, influencing splanchnic circulation. In anesthetized pigs, the external jugular vein, femoral artery and vein were cannulated unilaterally, and paramedian laparotomy was performed. In the anastomosis group, after resecting a bowel segment, end-to-end jejuno-jejunostomy was completed. Blood samples (from cannulas and by puncturing the portal vein) were taken before and after the intervention. Hematological, acid-base and blood gas parameters, metabolites, red blood cell (RBC) deformability and aggregation were determined. The highest hematocrit was found in portal blood, increasing further by the end of operation. A significant pH decrease was seen, and portal blood showed the highest lactate and creatinine concentration. The highest RBC aggregation values were found in arterial, the lowest in renal venous blood. The RBC aggregation increased with higher lactate concentration and lower pH. Osmotic gradient deformability declined, with the lowest values in portal and renal venous samples. In conclusion, micro-rheological parameters showed arterio-venous and porto-renal venous differences, influenced by oxygenation level, pH and lactate concentration. The intestinal anastomosis operation caused an immediate micro-rheological deterioration with portal venous dominancy in this experiment.

A Custom-Tailored Multichannel Pressure Monitoring System Designed for Experimental Surgical Model of Abdominal Compartment Syndrome.

In experimental medicine, a wide variety of sensory measurements are used. One of these is real-time precision pressure measurement. For comparative studies of the complex pathophysiology and surgical management of abdominal compartment syndrome, a multichannel pressure measurement system is essential. An important aspect is that this multichannel pressure measurement system should be able to monitor the pressure conditions in different tissue layers, and compartments, under different settings. We created a 12-channel positive-negative sensor system for simultaneous detection of pressure conditions in the abdominal cavity, the intestines, and the circulatory system. The same pressure sensor was used with different measurement ranges. In this paper, we describe the device and major experiences, advantages, and disadvantages. The sensory systems are capable of real-time, variable frequency sampling and data collection. It is also important to note that the pressure measurement system should be able to measure pressure with high sensitivity, independently of the filling medium (gas, liquid). The multichannel pressure measurement system we developed was well suited for abdominal compartment syndrome experiments and provided data for optimizing the method of negative pressure wound management. The system is also suitable for direct blood pressure measurement, making it appropriate for use in additional experimental surgical models.

Hematological, Micro-Rheological, and Metabolic Changes Modulated by Local Ischemic Pre- and Post-Conditioning in Rat Limb Ischemia-Reperfusion.

In trauma and orthopedic surgery, limb ischemia-reperfusion (I/R) remains a great challenge. The effect of preventive protocols, including surgical conditioning approaches, is still controversial. We aimed to examine the effects of local ischemic pre-conditioning (PreC) and post-conditioning (PostC) on limb I/R. Anesthetized rats were randomized into sham-operated (control), I/R (120-min limb ischemia with tourniquet), PreC, or PostC groups (3 × 10-min tourniquet ischemia, 10-min reperfusion intervals). Blood samples were taken before and just after the ischemia, and on the first postoperative week for testing hematological, micro-rheological (erythrocyte deformability and aggregation), and metabolic parameters. Histological samples were also taken. Erythrocyte count, hemoglobin, and hematocrit values decreased, while after a temporary decrease, platelet count increased in I/R groups. Erythrocyte deformability impairment and aggregation enhancement were seen after ischemia, more obviously in the PreC group, and less in PostC. Blood pH decreased in all I/R groups. The elevation of creatinine and lactate concentration was the largest in PostC group. Histology did not reveal important differences. In conclusion, limb I/R caused micro-rheological impairment with hematological and metabolic changes. Ischemic pre- and post-conditioning had additive changes in various manners. Post-conditioning showed better micro-rheological effects. However, by these parameters it cannot be decided which protocol is better.

How does practice improve the skills of medical students during consecutive training courses?

PURPOSE:: To follow-up the development of medical students in taking a stitch using two different bench models, and to assess their performance with regards to gender, handedness, prior recreational activities and interest in surgery. METHODS:: The study was performed during the compulsory basic (n=152) and the consecutive elective course (n=27). Students took simple interrupted stitches into synthetic and biopreprate models in the classroom and in the operating room. The time needed for that was measured and the quality was scored, using an OSATS (Objective Structured Assessment of Technical Skill) checklist that had been adapted to our training programs. RESULTS:: Students' performance improved both in time and quality during classes, over the course and compared basic to the elective course, too. No significant difference was found in relation to gender and handedness but certain recreational activities and special interest in surgery led to better results. Operating room environment had a slight negative effect on students' performance. CONCLUSION:: The study could provide objective skill assessment, monitoring has revealed deficiencies and influencing factors. Objective feedback, valid and reliable assessment is important in teaching surgical skills. In addition it may contribute to higher surgical safety later on in the clinical practice.

How does practice improve the skills of medical students during consecutive training courses?

Abstract Purpose: To follow-up the development of medical students in taking a stitch using two different bench models, and to assess their performance with regards to gender, handedness, prior recreational activities and interest in surgery. Methods: The study was performed during the compulsory basic (n=152) and the consecutive elective course (n=27). Students took simple interrupted stitches into synthetic and biopreprate models in the classroom and in the operating room. The time needed for that was measured and the quality was scored, using an OSATS (Objective Structured Assessment of Technical Skill) checklist that had been adapted to our training programs. Results: Students' performance improved both in time and quality during classes, over the course and compared basic to the elective course, too. No significant difference was found in relation to gender and handedness but certain recreational activities and special interest in surgery led to better results. Operating room environment had a slight negative effect on students' performance. Conclusion: The study could provide objective skill assessment, monitoring has revealed deficiencies and influencing factors. Objective feedback, valid and reliable assessment is important in teaching surgical skills. In addition it may contribute to higher surgical safety later on in the clinical practice.

Comparative erythrocyte deformability investigations by filtrometry, slit-flow and rotational ektacytometry in a long-term follow-up animal study on splenectomy and different spleen preserving operative techniques: Partial or subtotal spleen resection and spleen autotransplantation.

BACKGROUND: Partial or subtotal spleen resection or spleen autotransplantation can partly preserve/restore the splenic filtration function, as previous studies demonstrated. OBJECTIVE: For better evaluation and follow-up of the various spleen-preserving operative techniques' effectiveness versus splenectomy, a composite methodological approach was applied in a canine experimental model. METHODS: Beagle dogs were subjected to control (n = 6), splenectomy (SE, n = 4), partial and subtotal spleen resection (n = 4/each) or spleen autotransplantation groups (AU, Furka's spleen-chip method, n = 8). The follow-up period was 18 postoperative (p.o.) months. Erythrocyte deformability was determined in parallel by bulk filtrometry (Carat FT-1 filtrometer), slit-flow ektacytometry (RheoScan D-200) and rotational ektacytometry (LoRRca MaxSis Osmoscan). RESULTS: By filtrometry, relative cell transit time increased in the SE group (mostly in animal Nr. SE-3), showing the highest values on the 3rd, 9th and in 18th p.o. months. Elongation index values decreased in this group (both by slit-flow and rotational ektacytometers). In general, AU and two resection groups' values were lower versus control and higher than in SE. CONCLUSIONS: Forasmuch in the circulation both elongation by shear stress and filtration occur, these various erythrocyte deformability testing methods together may describe better the alterations. Considering the possible complications related to functional asplenic-hyposplenic conditions, individual analysis of cases is highly important.

Usage of ultraviolet test method for monitoring the efficacy of surgical hand rub technique among medical students.

BACKGROUND: Adequate hand movements are essential in surgical hand rub, so it is important for medical students to learn it correctly. To assess its efficacy, we aimed to use ultraviolet (UV) light test after applying fluorescent solution. METHODS: Digital images of the hands of 253 medical students were analyzed during "Basic Surgical Techniques" course on the 10th (Survey 1) and 14th (Survey 2) week of the curriculum to check the process and the skills development. The last step of the surgical hand rub was performed with a fluorescent solution, and then the hands were placed under UV light. Photographs were taken and analyzed. Every uncovered area was considered an error. Number and the localization of missed spots and its extent was determined. For evaluation, palmar (P) and dorsal (D) sides of the hands were divided into regions of interest (1-distal phalanxes, 2-thumb and first metacarpus, 3-second to fifth fingers, and 4-second to fifth metacarpals). RESULTS: Various magnitude and number of failure occurred in 123 (48.61%) students in survey 1 and in 65 (25.69%) in survey 2. The most frequent sites of the missed spots were D/2 and P/4 region in survey 1 and D/1 and P/4 in survey 2. There was an improvement seen in survey 2, as shown by a decrease in the number and extent of missed spots. Right-handed students made fewer mistakes on their nondominant hands than left-handed students (n = 23) did. DISCUSSION: The method was suitable to monitor the efficacy of surgical hand rub technique and identify the mistakes and the critical sites. The main advantage of the UV test was the immediate feedback, which resulted in a distinct improvement. CONCLUSION: Applying the UV test to the medical education and training may contribute to improvement in the compliance and the efficacy of the technique of surgical hand rub among the students.

Testicular ischemia-reperfusion may alter micro-rheological parameters in laboratory rats.

Ischemia-reperfusion-caused hemorheological alterations have been widely studied but the effect of testicular ischemia-reperfusion has not so far. In this study 14 Sprague-Dawley rats were involved. In the ischemia-reperfusion group under general anaesthesia the left testis was explored by opening the scrotum then the deferent duct and vasculature were clamped for 30 minutes. Testicular microcirculation was monitored by laser Doppler flowmetry. The right testis was untouched. In the control group: only anaesthesia was induced. Blood sampling occurred before and after ischemia, at the 60th minute of reperfusion and on the 1st postoperative day for determining hematological parameters (microcell-counter), erythrocyte deformability (slit-flow ektacytometer) and erythrocyte aggregation (light-transmission aggregometer). After the last blood sampling, testicles were removed for histological examination. Hematological parameter changes reflected inflammatory response. Erythrocyte deformability showed a worsening already at the 60th minute of reperfusion compared to base and control values. By the 1st postoperative day further decrease was observed. Erythrocyte aggregation significantly enhanced with great magnitude versus base and control values (p < 0.001). However, conventional histological examinations did not show marked testicular injury. The experienced changes can attract attention to the testicular ischemia-reperfusion causing significant effects on hemorheological parameters, which can lead to further harmful microcirculatory consequences.