Hydrodynamic evaluations of four mock femoral venous cannulas

Abstract Objective: To report the results of four mock femoral venous cannulas and the hydrodynamical superiority of one of them, which is the completely punched (CP) model, upon the other three. Methods: Four simulated femoral venous cannulas (single-stage, two-stage, multi-stage, and CP model) were designed from a 1/4" x 1/16" x 68 cm polyvinyl chloride (PVC) tubing line for testing. Holes on the PVC tubes were opened by a 5 mm aortic punch. In order to evaluate the cannulas' drainage performance, gelofusine was used as fluid. The fluid was drained for 60 seconds by gravitation and then measured for each model separately. Results: Mean drained volumes of single-stage, two-stage, and multi-stage cannulas were 2.483, 2.561, and 2.603 mL, respectively. However, the CP cannula provided us a mean drained volume of 2.988 mL. There were significant differences among the variables of the CP cannula and the other three mock cannulas concerning the drained fluid flow (P<0.01). Conclusion: In our study, the measured mean volumes showed us that more drainage surface area provides better fluid drainage.

Functional performance of different venous limb options in simulated neonatal/pediatric cardiopulmonary bypass circuits

Abstract Objective: Hemodilution is a concern in cardiopulmonary bypass (CPB). Using a smaller dual tubing rather than a single larger inner diameter (ID) tubing in the venous limb to decrease prime volume has been a standard practice. The purpose of this study is to evaluate these tubing options. Methods: Four different CPB circuits primed with blood (hematocrit 30%) were investigated. Two setups were used with two circuits for each one. In Setup I, a neonatal oxygenator was connected to dual 3/16" ID venous limbs (Circuit A) or to a single 1/4" ID venous limb (Circuit B); and in Setup II, a pediatric oxygenator was connected to dual 1/4" ID venous limbs (Circuit C) or a single 3/8" ID venous limb (Circuit D). Trials were conducted at arterial flow rates of 500 ml/min up to 1500 ml/min (Setup I) and up to 3000 ml/min (Setup II), at 36°C and 28°C. Results: Circuit B exhibited a higher venous flow rate than Circuit A, and Circuit D exhibited a higher venous flow rate than Circuit C, at both temperatures. Flow resistance was significantly higher in Circuits A and C than in Circuits B (P<0.001) and D (P<0.001), respectively. Conclusion: A single 1/4" venous limb is better than dual 3/16" venous limbs at all flow rates, up to 1500 ml/min. Moreover, a single 3/8" venous limb is better than dual 1/4" venous limbs, up to 3000 ml/min. Our findings strongly suggest a revision of perfusion practice to include single venous limb circuits for CPB.

Comparison of two technics of cardiopulmonary bypass (conventional and mini CPB) in the trans-and postoperative periods of cardiac surgery / Comparação de duas técnicas de circulação extracorpórea (convencional e mini CEC), nos períodos trans e pós-operatório de cirurgia cardíaca

AbstractObjective:This study aimed to compare the effects of two different perfusion techniques: conventional cardiopulmonary bypass and miniature cardiopulmonary bypass in patients undergoing cardiac surgery at the University Hospital of Santa Maria - RS.Methods:We perform a retrospective, cross-sectional study, based on data collected from the patients operated between 2010 and 2013. We analyzed the records of 242 patients divided into two groups: Group I: 149 patients undergoing cardiopulmonary bypass and Group II - 93 patients undergoing the miniature cardiopulmonary bypass.Results:The clinical profile of patients in the preoperative period was similar in the cardiopulmonary bypass and miniature cardiopulmonary bypass groups without significant differences, except in age, which was greater in the miniature cardiopulmonary bypass group. The perioperative data were significant of blood collected for autotransfusion, which were higher in the group with miniature cardiopulmonary bypass than the cardiopulmonary bypass and in transfusion of packed red blood cells, which was higher in cardiopulmonary bypass than in miniature cardiopulmonary bypass. In the immediate, first and second postoperative period the values of hematocrit and hemoglobin were higher and significant in miniature cardiopulmonary bypass than in the cardiopulmonary bypass, although the bleeding in the first and second postoperative days was higher and significant in miniature cardiopulmonary bypass than in the cardiopulmonary bypass.Conclusion:The present results suggest that the miniature cardiopulmonary bypass was beneficial in reducing the red blood cell transfusion during surgery and showed slight but significant increase in hematocrit and hemoglobin in the postoperative period.

ResumoObjetivo:Este estudo teve como objetivo comparar os efeitos de duas técnicas de perfusão diferentes: convencional (CEC) e mini (MCEC) em pacientes submetidos à cirurgia cardíaca no Hospital Universitário de Santa Maria - RS.Métodos:Foi realizado um estudo retrospectivo, transversal, baseado em dados coletados dos pacientes operados entre 2010 e 2013. Foram analisados ​​os registros de 242 pacientes divididos em dois grupos: Grupo I - 149 pacientes submetidos à circulação extracorpórea e Grupo II - 93 pacientes submetidos à minicirculação extracorpórea.Resultados:O perfil clínico dos pacientes no pré-operatório foi semelhante nos grupos circulação extracorpórea e minicirculação extracorpórea sem diferenças significativas, exceto na idade, maior no grupo minicirculação extracorpórea. Os dados perioperatórios foram significativos de sangue coletadas para autotransfusão, que foram maiores no grupo com minicirculação extracorpórea do que a circulação extracorpórea e na transfusão de concentrado de hemácias, superior em circulação extracorpórea do que em minicirculação extracorpórea. Nos valores pós-operatório imediato, primeiro e segundo, os níveis de hematócrito e da hemoglobina foram maiores e significativos na minicirculação extracorpórea que no circulação extracorpórea, embora o sangramento no primeiro e segundo dias pós-operatórios tenha sido maior e significativo no minicirculação extracorpórea que no circulação extracorpórea.Conclusão:Os resultados sugerem que a minicirculação extracorpórea foi benéfica em reduzir a transfusão de células vermelhas do sangue durante a cirurgia e houve discreta, mas significativa, elevação do hematócrito e hemoglobina no pós-operatório.

Cardiopulmonary bypass: development of John Gibbon's heart-lung machine / Circulação extracorpórea: desenvolvimento da máquina de coração-pulmão de John Gibbon

Abstract Objective: To provide a brief review of the development of cardiopulmonary bypass. Methods: A review of the literature on the development of extracorporeal circulation techniques, their essential role in cardiovascular surgery, and the complications associated with their use, including hemolysis and inflammation. Results: The advancement of extracorporeal circulation techniques has played an essential role in minimizing the complications of cardiopulmonary bypass, which can range from various degrees of tissue injury to multiple organ dysfunction syndrome. Investigators have long researched the ways in which cardiopulmonary bypass may insult the human body. Potential solutions arose and laid the groundwork for development of safer postoperative care strategies. Conclusion: Steady progress has been made in cardiopulmonary bypass in the decades since it was first conceived of by Gibbon. Despite the constant evolution of cardiopulmonary bypass techniques and attempts to minimize their complications, it is still essential that clinicians respect the particularities of each patient's physiological function. .

Resumo Objetivo: Relatar de forma simples e resumida o desenvolvimento da circulação extracorpórea. Métodos: Realizada revisão de literatura sobre a evolução da circulação extracorpórea, seu papel fundamental para cirurgia cardiovascular e as complicações que podem surgir após o seu uso, dentre elas, a hemólise e a inflamação. Resultados: O processo de desenvolvimento da circulação extracorpórea foi fundamental, diminuindo as complicações desencadeadas por ela, que acabam por repercutir no paciente, variando de lesões de graus variados até falência de múltiplos órgãos. Os pesquisadores estudaram quais as agressões que a circulação extracorpórea poderia suscitar no organismo humano. Possíveis soluções surgiram e, consequentemente, meios mais adequados para uma condução mais segura do pós-operatório foram propostas. Conclusão: A circulação extracorpórea progrediu a passos firmes e seguros ao longo destas últimas décadas desde a sua concepção por Gibbon. Apesar da sua evolução e das condutas realizadas na tentativa de amenizar as complicações, o respeito aos detalhes das funções fisiológicas do paciente é fundamental. .

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass / Avaliação clínica da bomba espiral (Spiral Pump®) após aperfeiçoamentos introduzidos ao projeto original em pacientes submetidos a cirurgias cardíacas com circulação extracorpórea

Objective: The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. Methods: This study was performed in 52 patients (51% males), between 20 to 80 (67±14.4) years old weighing 53 to 102 (71.7±12.6) kg, mostly under myocardial revascularization surgery (34.6%) and valvular surgery (32.8%). Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+), lactate desidrogenase (UI/L), fibrinogen level (mg/dL) and platelet count (nº/mm3). Results: Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION: The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application. .

Objetivos: Apresentar resultados da aplicação da bomba espiral que emprega efeitos hidráulicos centrífugo e axial de bombeamento como elemento propulsor do circuito de circulação extracorpórea em pacientes submetidos a cirurgias cardíacas após modificações introduzidas no design do projeto original. Métodos: O estudo foi realizado em 52 pacientes (51% masculinos), com idade entre 20 a 80 (67±14,4) anos, peso 53 a 102 (71,7±12,6) kg, submetidos na maioria a cirurgia de revascularização miocárdica (34,6%) e Orovalvar (32,8%). Além das avaliações rotineiras, foram registrados rotação, tempo de CEC e para análise do impacto traumático à crase sanguínea, hemoglobina livre na urina (+ a 4+), desidrogenase láctica, fibrinogênio (mg/dL) e contagem de plaquetas (nº/mm3). Resultados: Observou-se a manutenção de parâmetros pressóricos e metabólicos adequados. Quanto aos marcadores de danos à crase sanguínea, as alterações estiveram proporcionais ao tempo maior de circulação extracorpórea. Os níveis de Hemoglobina Livre permaneceram com valores normais, com ligeiro aumento a partir dos 90 minutos de circulação extracorpórea. A Desidrogenase Láctica mostrou aumento, variando as medianas entre 550 a 770 UI/L enquanto o Fibrinogênio mostrou queda das medianas de 130 a 100 mg/dl. O número de plaquetas mostrou ligeira queda das medianas variando entre 240.000 a 200.000/mm3. Não ocorreram dificuldades de saída de perfusão, não se observou óbito imediato e todos os pacientes, exceto 1, obtiveram alta hospitalar. Conclusão: A bomba espiral aplicada como bomba propulsora de sangue durante cirurgia cardíaca se mostrou confiável e segura, não causou impacto traumático ...

Is declotting a better procedure than Redo MVR for stuck mitral valve?

To evaluate and compare the outcome of declotting versus Redo Mitral Valve replacement for stuck mitral valve in the early postoperative period. Retrospective interventional study. Armed Forces Institute of Cardiology and National Institute of Heart Diseases [AFICNIHD] Rawalpindi from 1[st] Jan, 2010 to 31[st] Oct, 2013. A total of 36 patients were selected. Group A [n = 28] underwent declotting and group B [n = 08] were treated by redo mitral valve replacement [MYR]. Diagnosis of prosthetic valve obstruction was made on the basis of history, clinical examination, echocardiography and fluoroscopy. All patients were operated under general anesthesia and cardiopulmonary bypass [CBP]. Total clamp and CPB time were recorded. Post operatively, patients were evaluated with daily progress parameter. The hemodynamic status, isotropic support, ventilation time, intensive care ward and total hospital stay were also recorded for comparison. Two-dimensional echocardiography was done before extubation and at discharge. Mortality rate was also compared in the two groups. No statistical difference was found on the basis of gender, age, interval between initial mitral valve replacement [MVR] and redo operation or decloting, anticoagulation status, New York Heart Association NYHA] functional class, international normalized ratio [INR] level, trans thoracic echocardiography and luoroscopy. The mean CBP time and cross clamp time was significantly less in group A than group B. Similarly mean ventilation time in group A was significantly less than in group B. The mean ITC stay was and mean hospital stay was not statistically significant. The mortality rate in group A and B was 7.14% and 50% respectively which was statistically significant. Prosthetic valve thrombosis is a life threatening complication after mechanical mitral valve replacement with high mortality without timely and effective surgical intervention. Declotting, being a less aggressive surgical technique is recommended because of better outcome in terms of morbidity and mortality in the early post-operative period

Retrograde autologous priming in cardiopulmonary bypass in adult patients: effects on blood transfusion and hemodilution / Perfusato autólogo retrógrado no circuito de circulação extracorpórea em pacientes adultos: efeitos sobre a hemodiluição e transfusão de sangue

INTRODUCTION: Retrograde autologous priming (RAP) is a cardiopulmonary bypass (CPB) method, at low cost. Previous studies have shown that this method reduces hemodilution and blood transfusions needs through increased intra-operative hematocrit. OBJECTIVE: To evaluate RAP method, in relation to standard CPB (crystalloid priming), in adult patients. METHODS: Sixty-two patients were randomly allocated to two groups: 1) Group RAP (n = 27) of patients operated using the RAP and; 2) Control group of patients operated using CPB standard crystalloid method (n = 35). The RAP was performed by draining crystalloid prime from the arterial and venous lines, before CPB, into a collect recycling bag. The main parameters analyzed were: 1) CPB hemodynamic data; 2) Hematocrit and hemoglobin values; 3) The need for blood transfusions. RESULTS: It was observed statistically significant fewer transfusions during surgery and reduced CPB hemodilution using RAP. The CPB hemodynamic values were similar, observing a tendency to use lower CPB flows in the RAP group patients. CONCLUSION: This investigation was designed to be a small-scale pilot study to evaluate the effects of RAP, which were demonstrated concerning the CPB hemodilution and blood transfusions.

INTRODUÇÃO: Perfusato autólogo retrógrado (PAR) é uma técnica de circulação extracorpórea (CEC) com baixos custos. Estudos anteriores demonstraram que esta técnica reduz a hemodiluição e a necessidade de transfusões de sangue por meio do aumento do hematócrito intraoperatório. OBJETIVO: Avaliar técnica de PAR em relação à CEC técnica padrão (perfusato cristaloide) em pacientes adultos. MÉTODOS: Sessenta e dois pacientes foram aleatoriamente alocados em dois grupos: 1) Grupo PAR (n = 27), constituído por pacientes operados utilizando a técnica de PAR e; 2) Grupo Controle, constituído por pacientes operados utilizando técnica padrão de CEC com cristaloides (n = 35). A PAR foi realizada drenando-se o perfusato cristaloide das linhas arterial e venosa, antes da CEC, para uma bolsa coletora de recirculação. Os principais parâmetros analisados foram: 1) parâmetros hemodinâmicos da CEC; 2) valores de hematócrito e hemoglobina; e; 3) necessidade de transfusões de sangue. RESULTADOS: Observaram-se diferenças estatisticamente significativas de transfusão no intraoperatório e diminuição da hemodiluição em CEC utilizando PAR. Os valores hemodinâmicos durante a CEC foram semelhantes, observando-se tendência de utilização de fluxos menores na CEC dos pacientes do grupo PAR. CONCLUSÃO: O presente estudo foi projetado em pequena escala para avaliar os efeitos do PAR, o que foi demonstrado em relação aos já conhecidos efeitos na diminuição da hemodiluição em CEC e transfusão sanguínea, porém não mostrou vantagens hemodinâmicas em relação à técnica padrão com perfusato cristaloide.

Aortic arch replacement with moderate hypothermia and a modified three-pump circuit

A strategy employing moderate hypothermia for the replacement of the aortic arch is proposed to avoid the complications of profound hypothermic circulatory arrest. Two patients underwent the complete replacement of the aortic arch using three pumps - for the brain, thoracoabdominal aorta, and heart, respectively. There were no complications and the patients were extubated uneventfully. The method preserved the auto-regulation of the cerebral blood flow without high vascular resistance

Considerações sobre métodos de ajuste de bombas de roletes usadas em circulação extracorpórea: velocidade de queda e calibração dinâmica / Considerations on roller pumps setting methods used in cardiopulmonary bypass: drop rate and dynamic calibration

As bombas de roletes ocupam um papel de destaque entre os dispositivos utilizados na circulação extracorpórea, pois são responsáveis pela movimentação do sangue. O ajuste adequado desses equipamentos é fundamental para minimizar o trauma nas células sanguíneas. O presente trabalho analisou dois métodos para ajuste das bombas: o método de medida de velocidade de queda e a calibração dinâmica em dois modelos de bombas, com o objetivo de avaliar as suas variações e limitações práticas de uso em centro cirúrgico. A velocidade de queda foi medida em dois modelos de bombas de roletes e em três pontos do leito rígido com valor final calculado pela média entre eles. A calibração dinâmica foi medida sequencialmente às medidas de velocidade de queda, e os valores médios de pressão foram registrados em arquivo, com intervalo entre medidas de 20 ms. Os valores médios de velocidade de queda mostraram diferenças significantes (p < 0,0007), quando comparados com os valores mínimos e entre os dois modelos de bombas. Nos dois métodos analisados foram observadas variações de ajuste entre os roletes, com possíveis consequências para a hemólise. A bomba 1 mostrou descentralização do leito rígido entre os pontos medidos (p < 0,02). O método de ajuste por medida de velocidade de queda mostrou erros em seus valores absolutos e com dificuldade de repetitividade e não foi possível estabelecer correlação com a respectiva medida de calibração dinâmica.

Roller pumps have an important role among the devices used in cardiopulmonary bypass, being responsible for pumping blood. The setting of pumps is essential to minimize the trauma on blood cells. This study examined two methods for pump adjustment: the drop rate method and dynamic calibration method, applied to two different pumps in order to evaluate their variations and practical limitations of use in operating room. The drop rate was measured in the lowest point of pump raceway (0º) and in two other points close to it (–20º and +20º) and the average values of the three points was also taken. The dynamic calibration was measured sequentially, and the pressure average values were recorded on file with a sampling interval of 20 ms. There were significant differences (p < 0.0007) in drop rate averages when compared with the lowest point in the two types of pumps. In two pumps were observed variations in settings between rollers with possible consequences for the hemolysis. The pump 1 showed decentralization in raceway between points measured (p < 0.02). The drop rate method showed errors in their absolute values and with limited repeatability, and it was not possible to correlate with their dynamic calibration measurements.

Nova técnica: operação de Norwood com perfusão regional cerebral e coronariana / New technique: Norwood operation with regional cerebral and coronary perfusion

Objetivo: Avaliar o resultado imediato da operação de Norwood modificado com nova técnica de perfusão regional cerebral (PRCeA) anterógrada associado a perfusão regional coronariana (PRCoR) retrógrada em substituição à parada circulatória total com hipotermia profunda em crianças portadoras da Síndrome da Hipoplasia do Coração Esquerdo (SHCE) com aorta ascendente extremamente hipoplásica (AH). Métodos: No período de dezembro de 2006 a fevereiro de 2008, a operação de Norwood modificado com tubo entre o ventrículo direito e as artérias pulmonares ou shunt tipo Sano foi realizada em oito crianças portadoras de SHCE e aorta ascendente com diâmetro inferior a 3 mm, (quatro do sexo masculino e quatro do sexo feminino) com idade média de 9,2 dias (variando de 1 a 29 dias) e peso médio de 3,3 kg (variando de 2,7 a 3,8 kg). Utilizada CEC e hipotermia a 25ºC com duas cânulas venosas e anastomose de um enxerto de politetrafluoretileno com a artéria inominada utilizado como linha arterial e para PRCeA. A PRCoR foi realizada por meio de um desvio na linha arterial e colocação de um cateter na aorta ascendente. Foram analisados o resultado cirúrgico imediato e a presença de alterações neurológicas nesse período. Resultados: O resultado cirúrgico imediato revelou mortalidade de 25 por cento e ausência de comprometimento neurológico ao exame clínico. Conclusão: A operação de Norwood modificado pode ser realizada com PRCeA e PRCoR em crianças com SHCE e AH com resultado cirúrgico imediato satisfatório e ausência de complicações neurológicas.

Objective: To assess the immediate result of the modified Norwood procedure with new technique of anterograde regional cerebral perfusion (ARCeP) and retrograde regional coronary perfusion (RRCoP) in substitution of profound hypothermia and circulatory arrest in children with hypoplastic left heart syndrome (HLHS) with extremely hypoplastic ascending aorta (HA). Methods: In the period of December of 2006 to February 2008 the modified Norwood procedure with tube between the right ventricle and pulmonary arteries or Sano shunt was performed in eight children with HLHS and with ascending aorta diameter less than 3 mm, (four male and four female) with median age of 9.2 days (ranging from 1 to 29 days) and median weigh of 3.3 kg (ranging from 2.7 to 3.8 kg). We used cardiopulmonary bypass and hypothermia at 25ºC with two venous cannulas and suture with a polytetrafluoroethylene graft sutured to the innominate artery as an arterial line and used to ARCeP. The RRCoP was performed by a deviation in the arterial line and placement of a catheter in the ascending aorta. The immediate surgical results and the clinical neurological manifestation were assessed. Results: The immediate surgical results revealed mortality of 25 percent and there were absence of neurological injury at clinical examination. Conclusions: The modified Norwood procedure can be accomplished with ARCeP and RRCoP in children with HLHS with HA with satisfactory immediate surgical result and without neurological complications.

Visualização de refluxo em aspirador de sangue e reservatório de cardiotomia usados em circulação extracorpórea / Flow visualization in blood aspirator and cardiotomy reservoir used in cardiopulmonary bypass

Objetivo: Um dos maiores danos causados pela oclusão em bombas de rolete é a hemólise. Estudos comparativos entre bomba de roletes com ajustes não oclusivos e bombas centrífugas têm sido realizados nas últimas décadas na tentativa de desenvolver novos produtos e ajustes que causem menos trauma aos elementos figurados do sangue. Comumente as bombas de rolete são ajustadas pelo método estático devido à preocupação com fluxos variáveis que podem ocorrer com ajustes não oclusivos. Folga excessiva nos roletes permite refluxo e pode acarretar erros no cálculo dos fluxos pela rotação da bomba, de acordo com os dispositivos adicionados ao circuito e a resistência sistêmica do paciente. O objetivo desse trabalho é avaliar o refluxo causado por dois modelos de bombas de rolete em aspirador de sangue e em reservatório de cardiotomia. Métodos: A visualização do refluxo foi realizada em aspirador de sangue e, em reservatório de cardiotomia, a visualização foi acompanhada de respectiva medida. Foram testados dois modelos de bombas de rolete de diferentes fabricantes, ajustadas pelo método de velocidade de queda e calibração dinâmica. Os testes foram conduzidos com tubos de silicone de 3/8 x 1/16 e 1/2 x 3/32 polegadas de diâmetro em água e solução análoga ao sangue. Resultados: Foram registrados visualmente os refluxos em aspirador de sangue e em reservatório de cardiotomia, com respectiva medida dos valores. As bombas apresentaram diferenças nos refluxos medidos ajustadas pelo método de calibração dinâmica. A bomba #2 apresentou refluxo, ajustada totalmente ocluída. Conclusão: Os refluxos medidos nos dois modelos de bomba apresentaram diferenças (P<0,008). Os resultados indicam diferenças nas características construtivas ocasionadas pelo processo de fabricação, projeto ou possíveis desgastes. Ajustes pouco oclusivos podem proporcionar variações nos fluxos com a resistência adicionada ao circuito, com dificuldade de correção do fluxo pelo incremento da rotação.

Objective: One of the major damage caused by occlusion in roller pumps is hemolysis. Comparative studies between roller pump with adjustments non occlusive and centrifugal pumps have been made in recent decades in an attempt to develop new products and adjustments that cause fewer traumas to the figurative elements of blood. Usually the roller pumps are adjusted by the static method due to concern variables flow that can occur with non-occlusive settings. Excessive slack in the rollers provoke back flow and can provides errors in the calculation of flow by the rotation of the pump, according to the devices added to the circuit and the systemic resistance of the patient. The objective of this study is to evaluate the back flow caused by two types of roller pumps in blood aspirator and cardiotomy reservoir. Method: Back flow visualization was performed in blood aspirator and cardiotomy reservoir. It was tested two different models of roller pumps, adjusted by drop rate and dynamic calibration. The tests were conducted with silicone tubes of 3/8 x 1/16 e 1/2 x 3/32 inches in diameter in water and solution similar to blood. Results: We recorded back flow visually in blood aspirator and in cardiotomy reservoir with their measure of values. The pumps had differences in refluxes measured adjusted by the dynamic calibration method. Pump#2 presents back flow adjusted fully occluded. Conclusion: The back flow measured in two models of pump present differences (P <0.008). The results indicate differences in its characteristics caused by the process of manufacturing, design or possible wear. Non-occlusive adjustments may cause variations in flow with the increase of resistance added to the circuit, with difficulty to fix the flow by increasing the rotation.

Análise do perfil hidrodinâmico em diferentes modelos de bombas de rolete utilizadas em circulação extracorpórea / Analysis of the hydrodynamic profile in different roller pumps models used in cardiopulmonary bypass

OBJETIVO: Dentre os equipamentos utilizados em circulação extracorpórea, as bombas de rolete têm grande importância, com diversos modelos disponíveis de vários fabricantes. A calibração é um fator importante nas taxas de hemólise e o seu potencial difere em cada uma delas. Pesquisadores nem sempre abordam detalhes sobre os perfis do leito rígido, supondo que as formas padronizadas de calibração garantem valores iguais e comparáveis para todos os modelos de bombas de rolete. Dispomos principalmente de dois métodos para a calibração das bombas, o que também interfere com o potencial hemolítico. Nenhum dos métodos considera as características de impulsão do fluído, definido pela forma construtiva do leito rígido. O objetivo é avaliar o perfil hidrodinâmico de três modelos de bombas de roletes disponíveis no mercado brasileiro. MÉTODOS: A oclusão dos roletes foi feita por medidas de velocidade de queda e calibração dinâmica. Foram utilizados dois diferentes diâmetros de tubos de silicone (3/8 x 1/16 e 1/2 x 3/32 polegadas). RESULTADOS: Os perfis apresentaram diferenças em suas variâncias. P<0,01 para medidas de velocidade de queda e P<0,0001 para medidas de calibração dinâmica. Foram encontradas diferenças nas variações de pressão entre as bombas analisadas (P<0,002). CONCLUSÃO: As medidas de oclusão são dependentes da forma do leito rígido e comparações envolvendo bombas de rolete devem ser feitas com cautela. Testes com sangue deveriam ser realizados para verificar a influência das variações de pressão na hemólise.

OBJECTIVE: Among the equipments used in cardiopulmonary bypass the roller pumps have great importance with various models available from several manufacturers. The calibration is an important factor in hemolysis rates and its potential is different in each. Researchers do not always approach details on the pump bed profiles assuming that the standardized calibration settings ensure equal and comparable values for all models of roller pumps. We have mainly two methods for calibration of pumps which also interferes on the hemolytic potential. In both of them, the characteristics of fluid impulsion defined by the pump bed design are not considered. The aim of this study is to compare the hydrodynamic profile of three models of roller pumps available in the Brazilian market. METHODS: The rollers occlusion was performed by measures of drop and dynamic calibration. Two different silicone diameter tubes were used (3/8 x 1/16 and 1/2 x 3/32 inches). RESULTS: The profiles showed differences in their variances, P<0.01 for drop rate measures and P<0.0001 for dynamic calibration. Different changes in pressure were found between the pumps analyzed (P<0.002). CONCLUSION: The measures of occlusion are dependent on the design of the pump bed and comparisons involving roller pumps should be performed with caution. Blood tests should be performed to verify the influence of changes in hemolysis pressure.

Changes in near infrared spectroscopy during deep hypothermic circulatory arrest.

Monitoring cerebral oxygenation with near infrared spectroscopy may identify periods of cerebral desaturation and thereby the patients at risk for perioperative neurocognitive issues. Data regarding the performance of near infrared spectroscopy monitoring during deep hypothermic circulatory arrest are limited. The current study presents data regarding use of a commercially available near infrared spectroscopy monitor during deep hypothermic circulatory arrest in paediatric patients undergoing surgery for congenital heart disease. The cohort included 8 patients, 2 weeks to 6 months of age, who required deep hypothermic circulatory arrest for repair of congenital heart disease. The baseline cerebral oxygenation was 63 +/- 11% and increased to 88 +/- 7% after 15 min of cooling to a nasopharyngeal temperature of 17-18 degrees C on cardiopulmonary bypass. In 5 of 8 patients, the cerebral oxygenation value had achieved its peak value (either >or=90% or no change during the last 2-3 min of cooling on cardiopulmonary bypass). In the remaining 3 patients, additional time on cardiopulmonary bypass was required to achieve a maximum cerebral oxygenation value. The duration of deep hypothermic circulatory arrest varied from 36 to 61 min (43.4 +/- 8 min). After the onset of deep hypothermic circulatory arrest, there was an incremental decrease in cerebral oxygenation to a low value of 53 +/- 11%. The greatest decrease occurred during the initial 5 min of deep hypothermic circulatory arrest (9 +/- 3%). Over the entire period of deep hypothermic circulatory arrest, there was an average decrease in the cerebral oxygenation value of 0.9% per min (range of 0.5 to 1.6% decline per minute). During cardiopulmonary bypass, cooling and deep hypothermic circulatory arrest, near infrared spectroscopy monitoring followed the clinically expected parameters. Such monitoring may be useful to identify patients who have not achieved the highest possible cerebral oxygenation value despite 15 min of cooling on cardiopulmonary bypass. Future studies are needed to define the cerebral oxygenation value at which neurological damage occurs and if interventions to correct the decreased cerebral oxygenation will improve perioperative outcomes.

Circulação extracorpórea em adultos no século XXI: ciência, arte ou empirismo?: [revisão] / Adult cardiopulmonary bypass in the twentieth century: science, art or empiricism?: [review]

A presente revisão tem por objetivo ressaltar alguns aspectos pouco discutidos da circulação extracorpórea (CEC), levando-se em consideração fisiologia, fisiopatologia e algumas novas tecnologias de perfusão. Assim, alguns aspectos, até certo ponto filosóficos, motivaram a elaboração dessa revisão: a) Preservar e atualizar os conhecimentos do cirurgião sobre a CEC, pelo simples fato de manter a sua liderança pedagógica sobre a sua equipe; b) Questionar se pacientes idosos e diabéticos pelas suas características individuais, assim como adotado para crianças, talvez merecessem protocolos mais apropriados; c) Questionar a reação inflamatória sistêmica causada pela exposição do sangue à superfície não endotelizada do circuito de CEC diante da importância crescente do contato do sangue com a ferida cirúrgica; d) Em relação ao tratamento da síndrome vasoplégica, o azul de metileno continua sendo a melhor opção terapêutica, embora, muitas vezes não seja eficiente pela existência de uma "janela terapêutica" embasada na dinâmica da ação da guanilato ciclase (saturação e síntese "de novo") e; finalmente, e) Razão da escolha do título, ressaltando que, em seus moldes atuais, a CEC seria conseqüência do empirismo, arte, ou da ciência? A mensagem final vem com a convicção de que tanto o empirismo, a arte e a ciência são muito fortes em se tratando da CEC.

The aim of the present review is to highlight some less discussed aspects of the cardiopulmonary bypass (CPB), taking into consideration the physiology, physiopathology, and some new technologies of perfusion. Thus, some points, to a certain extent philosophical, have motivated this revision: a) To preserve and update the surgeon knowledge regarding CPB, even to keep his/her pedagogical leadership on his/her surgical team; b) To question if elderly and diabetic patients, as a result of their individual characteristics deserve more appropriate protocols similar to those adopted for children; c) One third aspect would be the questioning of the systemic inflammatory reaction caused by the blood exposure to CPB non-endothelized circuit surface, in face of the increasing importance of blood contact with the surgical wound; d) In relation to the treatment of the vasoplegic syndrome, methylene blue continues being the best therapeutical option, even so, many times are not efficient on account of a highly probable existence of a "therapeutical window" based on the guanylate cyclase dynamics of action (saturation and synthesis "de novo") and; finally, e) The reason of the title, highlighting that based on its current patterns, would the CPB be an outcome of empiricism, art, or science? The bottom line of this article carries the certainty of that as much as the empiricism, art, and science are highly related to CPB.

Abordagem da valva do tronco pulmonar por desvio direito e uso de cânula bicaval: estudo experimental / Approach of the pulmonary valve using right heart bypass and bicaval cannula: experimental study

OBJETIVO: O objetivo deste estudo foi reproduzir a cirurgia de abordagem da valva do tronco pulmonar por desvio direito, avaliando-se uma nova cânula venosa bicaval com balonetes insufláveis para uso por miniacesso. MÉTODOS: Utilizaram-se 15 suínos da raça Large-White, sendo cinco para a padronização técnica das vias de acesso e monitorização hemodinâmica, nove submetidos ao experimento por meio de esternotomia, e um animal excluído da amostra, operado por mínimo acesso ao tórax. O desvio direito foi estabelecido pela drenagem bicaval, sendo a cânula introduzida pela veia jugular interna direita e locada nas veias cavas cranial e caudal. Os parâmetros medidos foram: Pressão Arterial Média (PAM); Freqüência Cardíaca (FC); Saturação O2 (SAT O2); Capnografia (PetCO2) e Temperatura (T). A análise estatística foi feita comparando-se os valores antes e durante o desvio direito. RESULTADOS: No momento pré-desvio direito, obtiveramse os seguintes valores médios: PAM = 90,8 mmHg, FC = 101,6 bat/min, SAT O2 = 93,8 por cento, PetCO2 = 28,4 mmHg, T = 36,1ºC. Durante o desvio direito, obtiveram-se os seguintes valores médios: PAM = 88,1 mmHg, FC = 98,0 bat/min, SAT O2 = 93,1 por cento, PetCO2 = 25,3 mmHg e T = 36,9ºC. Comparandose as médias obtidas entre os dois momentos, verificou-se não haver diferenças significantes para a PAM, FC e SAT O2 e diferenças significantes para a PetCO2 e a T. CONCLUSÃO: A cânula bicaval com balonetes promoveu drenagem eficaz de ambas as veias cavas, permitindo a manutenção dos parâmetros hemodinâmicos durante o desvio direito, sendo possível realizar a abordagem da valva pulmonar.

OBJECTIVE: To reproduce the surgery for correction of pulmonary valve anomalies using right heart bypass and a new bicaval cuffed venous cannula for minimal access surgery. METHODS: Fifteen Large-White pigs were used for this study. The standard technique model was established with the first five pigs, the experiment was done with nine animals by sternotomy, and one was submitted to a minimally invasive procedure, but has been excluded of the sample. Bicaval drainage by a single cannula was obtained through the internal jugular vein. The cuffs were inflated to increase blood flow to the machine. The return was established by putting the arterial cannula into the pulmonary artery trunk. Pre-bypass parameters were measured and compared with the parameters during the right bypass: Median Arterial Tension (MAT); Heart Rate (HR); O2 Saturation (SAT O2); end-tidal CO2 measures (etCO2); Temperature (T). The statistical analysis was done comparing the pre-bypass and during bypass values. RESULTS: Pre-bypass values: MAT: 90.8 mmHg; HR = 101.6 beat/min; O2 SAT = 93.8 percent; PetCO2 = 28.4 mmHg; T = 36.1ºC. During bypass the obtained values were: MAT: 88.1 mmHg; HR = 98.0 beat/min; O2 SAT = 93.1 percent; PetCO2 = 25.3 mmHg; T = 36.9ºC. Comparing the average values between the two abovementioned moments, no significant difference occurred in MAT, HR and O2 SAT; PetCO2 and T presented significant differences. CONCLUSIONS: The bicaval cuffed venous cannula showed efficient drainage of both venae cavae with appropriate hemodynamic parameters during right bypass allowing access to the pulmonary valve.