Closed-Loop Doluisio (Colon, Small Intestine) and Single-Pass Intestinal Perfusion (Colon, Jejunum) in Rat-Biophysical Model and Predictions Based on Caco-2.

PURPOSE: The effective rat intestinal permeability (P eff ) was deconvolved using a biophysical model based on parameterized paracellular, aqueous boundary layer, transcellular permeabilities, and the villus-fold surface area expansion factor. METHODS: Four types of rat intestinal perfusion data were considered: single-pass intestinal perfusion (SPIP) in the jejunum (n = 40), and colon (n = 15), closed-loop (Doluisio type) in the small intestine (n = 78), and colon (n = 74). Moreover, in vitro Caco-2 permeability values were used to predict rat in vivo values in the rat data studied. RESULTS: Comparable number of molecules permeate via paracellular water channels as by the lipoidal transcellular route in the SPIP method, although in the closed-loop method, the paracellular route appears dominant in the colon. The aqueous boundary layer thickness in the small intestine is comparable to that found in unstirred in vitro monolayer assays; it is thinner in the colon. The mucosal surface area in anaesthetized rats is 0.96-1.4 times the smooth cylinder calculated value in the colon, and it is 3.1-3.6 times in the small intestine. The paracellular permeability of the intestine appeared to be greater in rat than human, with the colon showing more leakiness (higher P para ) than the small intestine. CONCLUSION: Based on log intrinsic permeability values, the correlations between the in vitro and in vivo models ranged from r2 0.82 to 0.92. The SPIP-Doluisio method comparison indicated identical log permeability selectivity trend with negligible bias.

Optimisation of Volume Flow Rates when Using Endovascular Shunting Techniques: An Experimental Study in Different Bench Flow Circuits.

Objective: Acute tissue ischaemia may arise due to arterial emergencies or during more complex vascular procedures and may be mitigated by temporary shunting techniques.Endovascular shunting (ES) techniques enable percutaneous access and shunting from the donor artery without the need to completely interrupt the arterial flow in the donor artery. An endoshunt system may also cover longer distances than most conventional shunts. The aim was to investigate and optimise the flow rates in different endovascular shunt systems. Methods: Step 1: The flow capacity of different ES configurations was compared with the flow capacity of a 9 Fr Pruitt-Inahara shunt (PIS). An intravenous bag with 0.9% NaCl, pressurised to 90 mmHg, was connected simultaneously to a PIS and to one of the tested ES configurations. The two shunt systems were then opened at the same time.The delivered fluid volumes from the shunt systems were collected and measured. The volume flow rate was subsequently calculated.Steps 2 and 3: Within a heart lung machine circuit, pressure-flow charts were constructed for the individual ES components and for the fully connected optimised endoshunt systems. The flow rate was increased in steps of 40-50 mL/min while monitoring the driving pressure, enabling the creation and comparison of the pressure-flow charts for the individually tested components. In total, seven individual inflow and outflow potential ES components were investigated with inflow and outflow diameters ranging from 6 to 15 Fr. Results: ES systems based on standard donor introducers led to substantially lower volume flow than the corresponding PIS volume flow, whereas ES systems based on dedicated 6 or 8 Fr dialysis access introducers (Prelude Short Sheet, Merit Medical) matched PIS flow rates. The introduction of 30 cm long »'' perfusion tubing within the ES system did not affect volume flow for any of the tested ES configurations. Conclusion: Endoshunting techniques can match PIS volume flow rates over short and long distances. The achieved ES flow rate is highly dependent on the components used within the ES system.

Corrigendum to "Optimization of Volume Flow Rates when Using Endovascular Shunting Techniques - An Experimental Study in Different Bench Flow Circuits. [EJVES Vascular Forum Volume 58, 2023, Pages 5-10]".

[This corrects the article DOI: 10.1016/j.ejvsvf.2022.11.002.][This corrects the article DOI: 10.1016/j.ejvsvf.2023.03.001.].

Isolated heart models for studying cardiac electrophysiology: a historical perspective and recent advances.

Experimental models used in cardiovascular research range from cellular to whole heart preparations. Isolated whole hearts show higher levels of structural and functional integration than lower level models such as tissues or cellular fragments. Cardiovascular diseases are multi-factorial problems that are dependent on highly organized structures rather than on molecular or cellular components alone. This article first provides a general introduction on the animal models of cardiovascular diseases. It is followed by a detailed overview and a historical perspective of the different isolated heart systems with a particular focus on the Langendorff perfusion method for the study of cardiac arrhythmias. The choice of species, perfusion method, and perfusate composition are discussed in further detail with particular considerations of the theoretical and practical aspects of experimental settings.

Disposal of donor livers in Brazil: how to optimize their utilization rate in transplants? / Descarte de fígados de doadores no Brasil: como otimizar sua taxa de utilização em transplantes?

ABSTRACT Objective: To understand the professionals´ perception of the use of deceased donor liver for transplantation, the reasons to decline them, and propose strategies to increase their use safely. Methods: This is a cross-sectional, descriptive qualitative-quantitative study. Professionals working with liver transplantation answered a self-administered, structured, and electronic questionnaire comprising 17 questions distributed into four sessions (demographic factors, perception of use of organs, reasons for disposal, and measures to favor their usage). Results: A total of 42 professionals participated in the study. The rate of use of organs was considered low by 71.43% (n=30) of respondents or very low by 19.05% (n=8). Everyone agreed that it was possible to increase it. Thirty-one (73.81%) participants believed the expansion of the population of extended criteria donors affected this index negatively. Donor-related conditions were the most frequent category of reasons for refusing a liver for transplantation, being the findings during organ retrieval the most frequent reason in clinical practice. Enhanced training of intensive care teams in the treatment of donors was the primary measure selected to favor the use of the organs, followed by investment in new technologies to optimize its preservation/evaluate its function before transplantation. Conclusion: Implementation of strategies to increase the rate of acceptance of livers is expected. Improvements in donor intensive care and implementation of new preservation technologies should favor the use of the organs.

RESUMO Objetivo: Compreender a percepção dos profissionais acerca do uso de fígado de doadores falecidos para transplante e os motivos para sua recusa, além de propor estratégias para ampliar sua utilização com segurança. Métodos: Estudo do tipo transversal, descritivo qualiquantitativo.Profissionais que trabalhavam com transplante hepático responderam a um questionário autoaplicável, estruturado e eletrônico, composto de 17 questões distribuídas em quatro seções (fatores demográficos, percepção sobre a utilização dos órgãos, razões para o descarte e medidas para favorecer sua utilização). Resultados: Participaram do estudo 42 profissionais. A taxa de utilização dos órgãos foi considerada baixa por 71,43% (n=30) dos respondentes ou muito baixa por 19,05% (n=8). Todos concordaram que era possível aumentá-la. Trinta e um (73,81%) participantes acreditavam que a expansão da população de doadores de critérios estendidos impacta negativamente nesse índice. Condições relacionadas ao doador foi a categoria mais frequente de razões para a recusa de um fígado para transplante, sendo os achados durante a cirurgia de extração o motivo mais frequente na prática clínica. O melhor treinamento das equipes da terapia intensiva nos cuidados com os doadores foi a principal medida selecionada para favorecer a utilização dos órgãos, seguido pelo investimento em novas tecnologias para otimizar sua preservação/avaliar sua função antes do transplante. Conclusão: A efetivação de estratégias para aumentar a taxa de aceite de fígados de doadores é aguardada. Melhorias no cuidado intensivo do doador e a implementação de novas tecnologias de preservação devem favorecer a utilização desses órgãos.

Brachiocephalic artery cannulation in proximal aortic surgery that requires circulatory arrest.

The brachiocephalic artery is an alternative cannulation site in the repair of ascending aortic lesions that require circulatory arrest. We evaluate the effectiveness and safety of this technique. Proximal aortic surgery was performed in 32 patients from 2006 through 2012 via brachiocephalic artery cannulation and circulatory arrest. Twenty-four (75%) of the patients were men. The mean age was 48.69 ± 9.43 years (range, 30-68 yr). Twelve had type I dissection, 2 had type II dissection, and 18 had true aneurysms of the ascending aorta. All operations were performed through a median sternotomy. The arterial cannula was inserted through an 8-mm vascular graft anastomosed to the brachiocephalic artery in an end-to-side fashion. In dissections, the distal anastomosis was performed without clamping the aorta. The patients were cooled to 24 °C, and circulatory arrest was established. The brachiocephalic and left carotid arteries were clamped, and antegrade cerebral perfusion was started at a rate of 10 mL/kg/min. Cardiopulmonary bypass was resumed after completion of the distal anastomosis and the initiation of rewarming. The proximal anastomosis was then performed. None of the patients sustained a major neurologic deficit, but 5 patients experienced transient postoperative agitation (<24 hr). There were 2 early deaths (6.25%), on the 3rd and the 11th postoperative days, both unrelated to the cannulation technique. Brachiocephalic artery cannulation through a graft can be a safe and effective technique in proximal aortic surgical procedures that require circulatory arrest.

Predictors of outcomes after correction of acute type a aortic dissection under moderate hypothermic circulatory arrest and antegrade cerebral perfusion

Abstract Introduction: Hypothermic circulatory arrest is widely used for correction of acute type A aortic dissection pathology. We present our experience of 45 consecutive patients operated in our unit with bilateral antegrade cerebral perfusion and moderate hypothermic circulatory arrest. Methods: Between January 2011 and April 2015, 45 consecutive patients were admitted for acute type A aortic dissection and operated emergently under moderate hypothermic circulatory arrest and bilateral antegrade cerebral perfusion. Results: Mean age was 58±11.4 years old. Median circulatory arrest time was 41.5 (30-54) minutes while the 30-day mortality and postoperative permanent neurological deficits rates were 6.7% and 13.3%, respectively. Unadjusted analysis revealed that the factors associated with 30-day mortality were: preoperative hemodynamic instability (OR: 14.8, 95% CI: 2.41, 90.6, P=0.004); and postoperative requirement for open sternum management (OR: 5.0, 95% CI: 1.041, 24.02, P=0.044) while preoperative hemodynamic instability (OR: 8.8, 95% CI: 1.41, 54.9, P=0.02) and postoperative sepsis or multiple organ dysfunction (OR: 13.6, 95% CI: 2.1, 89.9, P=0.007) were correlated with neurological dysfunction. By multivariable logistic regression analysis, postoperative sepsis and multiple organ dysfunction independently predicted (OR: 15.9, 95% CI: 1.05, 96.4, P=0.045) the incidence of severe postoperative neurological complication. During median follow-up of 6 (2-12) months, the survival rate was 86.7%. Conclusion: Bilateral antegrade cerebral perfusion and direct carotid perfusion for cardiopulmonary bypass, in the surgical treatment for correction of acute aortic dissection type A, is a valuable technique with low 30-day mortality rate. However, postoperative severe neurological dysfunctions remain an issue that warrants further research.

Bilateral pulmonary endarterectomy and Bentall procedure completed in one surgical session.

We describe the performance, in one surgical session, of bilateral pulmonary endarterectomy and a button-technique Bentall operation in a 68-year-old man. The patient had chronic thromboembolic pulmonary hypertension and an ascending aortic aneurysm with moderate aortic regurgitation. The procedures were concurrently completed during short periods of systemic circulatory arrest, with antegrade cerebral perfusion maintained through the brachiocephalic artery at a flow rate of 10 mL/min/kg. The patient's cerebral perfusion was monitored with use of near-infrared spectroscopy, to prevent symmetric bilateral values from falling below 20% of the base value. The patient experienced no multiorgan failure or neurologic sequelae and, by the 6th postoperative day, improved from New York Heart Association functional class IV to class I.The reliable maintenance of continuous antegrade cerebral perfusion made the lengthy combined operation feasible, with low risk. The use of near-infrared spectroscopy enabled real-time monitoring of the patient's cerebral blood flow. Our experience shows the possibility of safely performing lengthy or multiple procedures in one surgical session.