Effect of short-term ischemia on microcirculation and wound healing of adipocutaneous flaps in the rat

Abstract Purpose Composite flaps used in reconstructive surgery may intra- and postoperatively suffer from hypoperfusion and/or ischemia-reperfusion influencing wound healing. We aimed to follow-up the effect of ischemia on adipocutaneous flaps' wound healing and microcirculation. Methods In anesthetized rats groin flaps were formed bilaterally. In Control group the flaps were repositioned and sutured back. In Ischemia-Reperfusion (I/R) group before repositioning and suturing the flap pedicles were clamped for 60 minutes. Laser Doppler (LD) fluxmetry and temperature probes were applied on the cranial, central and caudal flap regions before/after preparation and ischemia, re-suturing, and on the 1st-3rd-5th-7th-14th postoperative days, before the final examinations and biopsies for histology. Results Flaps' skin temperature quickly recovered after repositioning. LD values were lower in the I/R group, reaching a significant level by the 3rd postoperative day, and remained lowered till the 14th day. The magnitude of alterations differed in the flap regions. Histologically normal wound healing process was seen, except for some I/R flaps, where hypertrophized mammary glands were found. Conclusions Short-term ischemia could influence flap microcirculation and wound healing, and may result in hypertrophized mammary glands. Laser Doppler could be used to evaluate intra- and postoperative microcirculatory changes and may have significance in predicting complications.

Experiences with basic microsurgical training programs and skill assessment methods at the University of Debrecen, Hungary

Abstract During the past decades microsurgical training programs together with skill assessment methods had been developing intensively worldwide. Concerning the teaching of basic techniques at various levels, we aimed to summarize the education program types and experiences at our department, in order to define the way of continuity. All in the hope that this summary might contain useful information for other educators as well. About 50 years ago, in the late 1960s, microsurgical basic education had been established in Debrecen. Since the 1990s multilevel education programs have been developed, starting in undergraduate years up to the postgraduate training, residency and continuous medical education programs. In the last three decades about 2,300 participants completed courses, including over 470 residents. The ones who already succeeded microsurgical course as medical students, during residency program could reach better results and skill development. Concluding thoughts, the traditional methods and special experiences are highly important in microsurgical education. The necessary duration and individual training approach are emphasized. Standardization (self and international), comparability, accessibility, providing milestones of microsurgical skills are key factors. Proper feedback and skill assessment (experiences, internationally recognized scores, or combinations) are indispensable, but have to be fitted to the characteristic elements of the course.

Is the early or delayed remote ischemic preconditioning the more effective from a microcirculatory and histological point of view in a rat model of partial liver ischemia-reperfusion?

Abstract Purpose: To compare early- and late-effect remote ischemic preconditioning (RIPC) by analysing the microcirculatory, hemodynamic and histological changes in partial liver ischemia-reperfusion of rats. Methods: 60-minute partial liver ischemia followed by 120-minute reperfusion was performed without (Control group, n=7) or with preconditioning. In RIPC groups a tourniquet was applied around the left thigh using 3 cycles of 10-minute ischemia/10-minute reperfusion, one (RIPC-1, n=7) or twenty-four hours (RIPC-24, n=7) before I/R. Hemodynamic and microcirculatory measurements were performed before and after ischemia and in 30th, 60th and 120th minute of reperfusion and histological examination at the end of reperfusion. Results: Blood pressure decreased in all groups followed by biphasic changes in Control group. In RIPC groups R120 values returned almost to normal. Heart rate increased in Control and RIPC-1 groups at R120, while RIPC-24 did not show significant changes. Microcirculation of non-ischemic liver stayed constant in Control and showed significant changes in RIPC-24 group, while in ischemic liver elevated by R120 in all groups. RIPC didn't reduce histological alterations. Conclusion: Considering the survival and the results, both remote ischemic preconditioning protocols had beneficial effect in hepatic ischemia-reperfusion, however the histopathological findings were controversial.

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.

Intra and postoperative evaluations of microcirculation and micro-rheological parameters in a rat model of musculocutaneous flap ischemia-reperfusion

PURPOSE:To examine how the ischemia-reperfusion injury of latissimus dorsi-cutaneous maximus (LDCM) musculocutaneous flap affects the microcirculatory (flap's skin surface) and hemorheological parameters, and whether an intraoperative deterioration would predictively suggest flap failure in the postoperative period.METHODS: Ten healthy male rats were subjected to the study. In Group I the left flap was sutured back after 2-hour, while the contralateral side was right after its elevation. In Group II the same technique was applied, but the pedicle of the left flap was atraumatically clamped for 2-hour. The contralateral side was left intact. On the flap skin surface laser Doppler tissue flowmetry measurements were done before and after and during the protocols applied in the groups. Microcirculatory and hemorheological examinations were done postoperatively.RESULTS: The microcirculatory parameters significantly decreased during immobilization and ischemia. Afterwards, all the regions showed normalization. In the retrospective analysis there was a prominent difference between the microcirculatory parameters of necrotic and survived flap during the early postoperative days (1-3) in Group II. Erythrocyte aggregation and deformability showed only slight differences.CONCLUSIONS: Two-hour ischemia and reperfusion caused deterioration in latissimus dorsi-cutaneous maximus flap microcirculation. Predicting the possible postoperative complication, the intraoperative laser Doppler measurement can be informative.

Skin microcirculatory changes reflect early the circulatory deterioration in a fulminant sepsis model in the pig

PURPOSE: In the pathophysiology of sepsis tissue perfusion dysfunction is a crucial driving force. Thus the early recognition is highly important. Concerning the early hours of bacteremia, and the systemic inflammatory response reaction leading to sepsis we aimed to investigate the micro- and macrocirculatory changes. METHODS: In 20 juvenile Hungahib pigs were anesthetized and the femoral artery and external jugular vein were prepared unilaterally and cannulated. For assisted ventilation tracheostomy was performed. In Sepsis group (n=11) live E. coli was intravenously administered (increasing concentration, 9.5x10∧6 in 3h). In Control group (n=9) bacteria-free saline was administered at the same volume. Modified shock index (MSI), core and skin temperature, and skin microcirculation (laser Doppler) were measured before inducing bacteremia then hourly for 4h. RESULTS: In Control group parameters were stable, while six animals in the Sepsis group died before the 4th hour. Core and skin temperature did not show significant alterations. In Sepsis group microcirculation showed a large impairment already by the 1st hour, while in MSI only by the 3rd hour. CONCLUSION: During bacteremia and the early phase of sepsis microcirculatory impairment can be detected soon, even hours before the deterioration in hemodynamic parameters in this porcine model. .

Early postoperative changes in hematological, erythrocyte aggregation and blood coagulation parameters after unilateral implantation of polytetrafluoroethylene vascular graft in the femoral artery of beagle dogs

PURPOSE: The failure of small-caliber vascular grafts still means a serious problem. Concerning the early postoperative complications we aimed to investigate the hemostaseological and hemorheological aspects of this issue in a canine model. METHODS: In the Control group only anesthesia was induced. In the Grafted group under general anesthesia a 3.5-cm segment was resected unilaterally from the femoral artery and replaced with a PTFE graft (diameter: 3 mm). On the 1st-3rd-5th-7th and 14th postoperative days the skin temperature of both hind limbs was measured, and blood sampling occurred for hematological, hemostaseological and hemorheological tests. RESULTS: The skin temperature of the operated versus intact limbs did not differ. In the Grafted group leukocyte count was elevated by the 1st postoperative day, while platelet count increased over the entire follow-up period. Fibrinogen concentration rose on the 1st-5th days, activated partial thromboplastin time increased on the 3rd-7th days. Erythrocyte aggregation was enhanced significantly on the 1st-5th days. In specimens taken on the 14th day, histologically we found matured thrombus narrowing the graft lumen. CONCLUSIONS: Small-caliber PTFE graft implantation into the femoral artery caused significant changes in several hemostaseological and hemorheological parameters. However, better clarifying the factors leading to early thrombosis of these grafts needs further studies. .

A modified microsurgical model for end-to-side selective portacaval shunt in the rat: intraoperative microcirculatory investigations

PURPOSE: To investigate the intraoperative microcirculatory changes of the affected organs (small bowel, liver and kidney) during the making of a modified selective portacaval (PC) shunt. METHODS: On ten anaesthetized Sprague-Dawley rats the selective end-to-side mesocaval anastomosis was performed, where only the rostral mesenteric vein is utilized and the portal vein with the splenic vein are left intact. Morphometric and microcirculatory investigations using a LDF device determining flux units (BFU) were carried out. RESULTS: After completing the shunts the microcirculatory flux values did not recover in the same manner on the surface of the small intestine, the liver or the kidney. BFU values showed deterioration in the small intestine and in the liver (p<0.001). During the reperfusion the BFU values improved, but not in the same manner. The small intestine values left behind the kidney and liver data. CONCLUSIONS: Technically, the advantages of the models include the selective characteristic, the mesocaval localization and the relatively easy access to those vessels. However, its major disadvantage is the time needed for positioning the vessels without coiling or definitive stretching. Intraoperative LDF may provide useful data on the microcirculatory affection of the organs suffering from hypoperfusion or ischemia during creating the shunts.

Long-term following-up of viability of spleen autotransplants in the Beagle canine model / Avaliação em longo prazo da viabilidade do autotransplante de baço em cães Beagle

PURPOSE: To examine the possible late complications of splenectomy or spleen autotransplantation in large laboratory animal model, in which we need non-invasive or minimal-invasive methods for long-term monitoring of the experimental animals. METHODS: Experimental groups of beagle dogs were: non-operated control, sham-operated control, splenectomy, spleen autotransplantation with 5 or 10 spleen-chips taken into the greater omentum (Furka's technique). Prior to operations, on the 1st postoperative week, monthly till the 6th as well as in the 9th and 12th month, hemorheological examinations were performed. In postoperative 12th month colloid scintigraphy and diagnostic laparoscopy were carried out. At the end of the investigation comparative morphological examinations were performed, too. RESULTS: From the 4th-5th postoperative month filtration function of spleen-autotransplants showed particular restoration compared to splenectomy group. However, the functional results did not reach the values of the control or sham-operated groups. Sham-operated control's scintigraphy nicely showed activity in the spleen. In spleen autotransplantation-groups scintigraphy indicated well the activity of spleen-chips. During diagnostic laparoscopy spleen-chips with their blood supply were found. Histologically, the structure of spleen­autotransplants was similar to normal splenic tissue. CONCLUSIONS: The autotransplants are regenerated, their functions have been partly restored, and thus spleen autotransplantation may prevent the possible complications of splenectomy. These parameters and the presented investigative protocol are suitable for long-term following-up of viability of the spleen-autotransplants.

OBJETIVO: Examinar as possíveis complicações tardias da esplenectomia ou do autotransplante de baço em modelo animal de grande porte, no qual faz-se necessário o uso de métodos não invasivos ou minimamente invasivos para monitorizar os animais de experimentação. MÉTODOS: Grupos experimentais de cães beagle foram: não-operados controle, sham-operados controle, esplenectomia, autotransplante de baço com 5 ou 10 fatias de baço colocados no grande omento (técnica de Furka). Antes das operações, na 1ª semana de pós­operatório, mensalmente até 6o.assim como no 9º. e 12º. mês, foram realizados exames hemorreológicos. No 12º. mês de pós-operatório, cintilografia colóide e laparoscopia diagnóstica foram realizadas. Ao final do experimento, exames morfológicos comparativos foram realizados também. RESULTADOS: A partir do 4º-5º mês pós-operatório, a função de filtração dos baços autotransplantados mostraram particular restauração comparados ao grupo esplenectomia. Entretanto, os resultados funcionais não alcançaram os valores dos grupos controle ou sham-operados. A cintilografia dos controles sham-operados mostraram atividade no baço. Nos grupos de autotransplante, a cintilografia indicou bem a atividade das fatias de baço. Durante a laparoscopia diagnóstica, as fatias de baço com seu suprimento sanguíneo foram encontrados. Histologicamente, a estrutura dos autotransplantes de baço foi similar ao tecido normal de baço. CONCLUSÕES: Os autotransplantes são regenerados, suas funções foram parcialmente restauradas, e então ao autotransplantate esplênico pode prevenir as possíveis complicações da esplenectomia. Estes parâmetros e o protocolo experimental são adequados para o seguimento em longo prazo da viabilidade de autotransplantes esplênicos.

Efeitos do alopurinol e precondicionamento na apoptose devido a isquemia-reperfusão em duplo segmento de jejuno em cães / Effects of allopurinol and preconditioning on apoptosis due to ischemia-reperfusion on a double jejunum-segment canine model

PURPOSE: To investigate the duration of apoptosis caused by ischemia-reperfusion in the intestine in a new double jejunum-segment model, and to analyze the protective effects of allopurinol or ischemic preconditioning (IPC). METHODS: In Experiment I for harvesting the double jejunum-segment model after laparotomy a 30-cm-long jejunum part was selected on mongrel dogs (n=24). End-to-end anastomoses were performed at both ends and in the middle of the jejunum part, creating two equal segments. In one segment ischemia was induced by occluding the supplying vessels, the other segment served as control. Tissue samples for detecting apoptosis were taken at 30th minutes, 1st, 2nd, 4th, 6th, 8th, 12th and 24th hours of reperfusion. In Experiment II using the same model the 4-hour reperfusion time period, allopurinol (50 mg/kg) pre-treated and IPC (3 cycles of 5x1) groups (n=5 per each) were also investigated. RESULTS: In Experiment I the greatest apoptotic activity was detected at the 4th and 6th hour of reperfusion (14.2 ± 1.31 and 16.3 ± 1.05 per visual field at 40x magnification). In Experiment II Using the 4-hour reperfusion time period allopurinol pre-treatment increased the apoptotic activity (10.72 ± 0.47 per 50 intestinal villi) approximately two-fold than the IPC (6.72 ± 0.46 per 50 intestinal villi) did (p<0.05). CONCLUSIONS: Apoptotic activity has a characteristic time curve, reaching the highest values between the 4th and 6th hours after 30-minute intestinal ischemia. Ischemic preconditioning seemed to be protective against the morphological changes caused by intestinal ischemia-reperfusion.

OBJETIVO: Investigar a duração da apoptose causada pela isquemia-reperfusão no intestino em um novo modelo de duplo segmento de jejuno e analisar os efeitos protetores do alopurinol ou precondicionamento isquêmico (IPC). MÉTODOS: No experimento I para obter o modelo do duplo segmento de jejuno, após a laparotomia, uma parte de 30cm de comprimento de jejuno foi selecionada em cães mestiços (n=24). Anatomoses T-T foram realizadas em ambas as extremidades no meio do segmento de jejuno, criando dois segmentos iguais. Em um segmento foi induzida isquemia por oclusão dos vasos que o irrigavam e o outro segmento foi usado como controle. Amostras de tecido para detecção da apoptose foram obtidos aos 30 minutos, 1h, 2h, 4h, 6h, 8h, 12h e 24 horas de reperfusão. No experimento II usando o mesmo modelo, no tempo de reperfusão de 4 horas, foram investigados dois outros grupos (n=5 cada) usando precondicionamento com alopurinol (50 mg/kg) e IPC (3 ciclos de 5x1). RESULTADOS: No experimento I a maior atividade de apoptose detectada foi às 4h e 6h de reperfusão (14,2 ± 1,31 e 16,3 ± 1,05 no campo visual de 40x). No experimento II usando o período de 4horas de reperfusão o pré-tratamento com alopurinol aumentou a atividade apoptótica (10,72 ± 0,47) aproximadamente 2 vezes mais do que o IPC (6,72 ± 0,46) (p<0,05). CONCLUSÕES: A atividade de apoptose tem uma curva caractetística, atingindo maiores valores entre a 4ª e a 6ª horas após 30 minutos de isquemia intestinal. O precondicionamento isquêmico parece proteger contra alterações morfológicas causadas pela isquemia-reperfusão intestinal.

Hematological and hemostaseological alterations after warm and cold limb ischemia-reperfusion in a canine model / Alterações hematológicas e hemostaseológicas após isquemia-reperfusão morna e fria de membro inferior em modelo canino

PURPOSE: Acute ischemia-reperfusion (I/R) of extremities means serious challenge in the clinical practice. Furthermore, the issue of preventive cooling is still controversial. In this canine model we investigated whether limb I/R -with or without cooling- has an influence on hematological and hemostaseological factors. METHODS: Femoral vessels were exposed and clamped for 3 hours. After release the clamps, 4-hour reperfusion was secured. The same procedures with cooling using ice bags, as well as warm and cold sham-operations were performed. Before operations, from the excluded limb by the end of ischemia, during the reperfusion, and for 5 postoperative days afterwards blood samples were collected for testing hematological and blood coagulation parameters. RESULTS: After I/R activated partial thromboplastin time was elongated on 2nd-4th postoperative days. The highest values were on the 2nd day in cold I/R group, accompanied by increased prothrombin time values. The hematological parameters and fibrinogen level showed non-specific changes. In excluded ischemic limb the blood composition showed controversial data. Cold ischemia induced larger alterations, however platelet count, hematocrit changed more expressly in warm ischemia. CONCLUSION: These results indicate the risk of coagulopathy following limb I/R on early post-eventually days, which risk is higher in the case of cold I/R.

OBJETIVO: Isquemia-Reperfusão aguda (I/R) de extremidades representa um desafio sério na prática clínica. Além disso, o tema de prevenção pelo resfriamento é ainda controverso. Nesse modelo canino, investigou-se se I/R de membros -com ou sem resfriamento- tem influência nos fatores hematológicos e hemostaseológicos. MÉTODOS: Os vasos femorais foram expostos e clampeados por 3 horas. Após liberação dos clampes, foi realizada a reperfusão por 4-horas. Os mesmos procedimentos com e sem resfriamento usando bolsas de gelo, assim como operações simuladas com e sem resfriamento foram realizados. Antes das operações, do membro excluído ao final da isquemia, durante a reperfusão e por 5 dias de pós-operatório, amostras sanguíneas foram colhidas para exames hematológicos e parâmetros de coagulação. RESULTADOS: Após I/R, o tempo de tromboplastina parcial ativada foi alargado no 2º.-4º. dias de pós-operatório. Os valores mais altos foram no 2º.dia no grupo deI/R fria, acompanhada pelo aumento dos valores do tempo de protrombina. Os parâmetros hematológicos e o nível de fibrinogênio mostraram mudanças não específicas. No membro isquêmico excluído a composição sanguínea mostrou dados controversos. A isquemia fria induziu maiores alterações, entretanto, a contagem de plaquetas e o hematócrito mudaram mais expressivamente na isquemia morna. CONCLUSÃO: Estes resultados indicam risco de coagulopatia após I/R de membros nos dias mais precoces após o evento, sendo mais elevado no caso da I/R fria.