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Objective: Usually only FDA-approved oxygenators are subject of studies by the international scientific community. The objective of this study is to evaluate two types of neonatal membrane oxygenators in terms of transmembrane pressure gradient, hemodynamic energy transmission and gaseous microemboli capture in simulated cardiopulmonary bypass systems. Methods: We investigated the Braile Infant 1500 (Braile Biomédica, São José do Rio Preto, Brazil), an oxygenator commonly used in Brazilian operating rooms, and compared it to the Dideco Kids D100 (Sorin Group, Arvada, CO, USA), that is an FDA-approved and widely used model in the USA. Cardiopulmonary bypass circuits were primed with lactated Ringer's solution and packed red blood cells (Hematocrit 40%). Trials were conducted at flow rates of 500 ml/min and 700 ml/min at 35ºC and 25ºC. Real-time pressure and flow data were recorded using a custom-based data acquisition system. For gaseous microemboli testing, 5cc of air were manually injected into the venous line. Gaseous microemboli were recorded using the Emboli Detection and Classification Quantifier. Results: Braile Infant 1500 had a lower pressure drop (P<0.01) and a higher total hemodynamic energy delivered to the pseudopatient (P<0.01). However, there was a higher raw number of gaseous microemboli seen prior to oxygenator at lower temperatures with the Braile oxygenator compared to the Kids D100 (P<0.01). Conclusion: Braile Infant 1500 oxygenator had a better hemodynamic performance compared to the Dideco Kids D100 oxygenator. Braile had more gaseous microemboli detected at the pre-oxygenator site under hypothermia, but delivered a smaller percentage of air emboli to the pseudopatient than the Dideco oxygenator.

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Abstract Objective: Usually only FDA-approved oxygenators are subject of studies by the international scientific community. The objective of this study is to evaluate two types of neonatal membrane oxygenators in terms of transmembrane pressure gradient, hemodynamic energy transmission and gaseous microemboli capture in simulated cardiopulmonary bypass systems. Methods: We investigated the Braile Infant 1500 (Braile Biomédica, São José do Rio Preto, Brazil), an oxygenator commonly used in Brazilian operating rooms, and compared it to the Dideco Kids D100 (Sorin Group, Arvada, CO, USA), that is an FDA-approved and widely used model in the USA. Cardiopulmonary bypass circuits were primed with lactated Ringer's solution and packed red blood cells (Hematocrit 40%). Trials were conducted at flow rates of 500 ml/min and 700 ml/min at 35ºC and 25ºC. Real-time pressure and flow data were recorded using a custom-based data acquisition system. For gaseous microemboli testing, 5cc of air were manually injected into the venous line. Gaseous microemboli were recorded using the Emboli Detection and Classification Quantifier. Results: Braile Infant 1500 had a lower pressure drop (P<0.01) and a higher total hemodynamic energy delivered to the pseudopatient (P<0.01). However, there was a higher raw number of gaseous microemboli seen prior to oxygenator at lower temperatures with the Braile oxygenator compared to the Kids D100 (P<0.01). Conclusion: Braile Infant 1500 oxygenator had a better hemodynamic performance compared to the Dideco Kids D100 oxygenator. Braile had more gaseous microemboli detected at the pre-oxygenator site under hypothermia, but delivered a smaller percentage of air emboli to the pseudopatient than the Dideco oxygenator.

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OBJECTIVES: Volatile anesthetics have cardioprotective properties that improve clinically relevant outcomes in cardiac surgery, and can be used during cardiopulmonary bypass (CPB) through adapted calibrated vaporizers together with air and oxygen (O2). The effect of volatile agents on the membrane oxygenator is unknown. The aim of this study was to evaluate, for the first time, the performance of semiporous polypropylene membrane oxygenators after the use of sevoflurane vaporized during CPB in cardiac surgery. DESIGN: A prospective, randomized, controlled trial. SETTING: Teaching hospital. PARTICIPANTS: Thirty-two consecutive patients scheduled to undergo coronary artery bypass graft with CPB. INTERVENTIONS: Patients were allocated randomly to receive either a volatile anesthetic (sevoflurane 1%-3%, 16 patients) or an intravenous hypnotic (midazolam, 16 patients) during CPB. After surgery, the membrane oxygenators used during CPB were tested with regard to O2 transfer, carbon dioxide transfer, and pressure drop. MEASUREMENTS AND MAIN RESULTS: The authors observed no protocol deviation or crossover. The performance of the membrane oxygenator was similar between the 2 groups, as documented by O2 transfer (55±6.4 mL/min/L in the sevoflurane group versus 57±4.7 mL/min/L in the midazolam group, p = 0.4), carbon dioxide transfer, and pressure drop. CONCLUSIONS: The use of sevoflurane during CPB in cardiac surgery does not affect membrane oxygenator performance.

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OBJECTIVE: To analyze the security and efficacy of a new membrane oxygenator, the so-called OXM - 1500. METHODS: From May 2005 to September 2006, six sheep of Santa Inês breed (five male and one female, respectively) were studied. The average body weight was 14.1 (+/-5) kg, body surface 0.6 (+/-0.2) m(2) and a mean age 3.8 (+/-1.5) months. All of them were submitted to extracorporeal circulation (CEC) with evaluation at 10, 30, 60, 120, 180 and 240 minutes. The following values were obtained: values of oxygen transference (TTO2) and carbon dioxide transference (TTCO2), haemoglobin (HBS) and free haemoglobin (HBL), the score of platelets and of leucocytes, and heat transference rate. RESULTS: TTO2 and TTCO2 were adequate. Lesion of the majority formed blood elements was insignificant; there no modifications in HBS, HBL levels; platelets and leucocytes decreased over time. Heat exchange was effective (p < 0.05). CONCLUSIONS: The membrane OXM--1500 infant oxygenator, tested in sheep, showed adequate oxygenation capacity, CO2 removal capacity, and small alteration of haemoglobin and platelets without significant decrease of leucocytes, as expected. Heat exchanger connected to the oxygenator was efficient in temperature changes.

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OBJETIVO: Analisar a segurança e a eficácia de um novo oxigenador de membrana denominado OXM -1500. MÉTODOS: No período de maio de 2005 a setembro de 2006, foram estudados seis ovinos da raça Santa Inês, sendo cinco machos e uma fêmea, com peso corpóreo médio de 14,1 (±5) kg, superfície corpórea de 0,6 (±0,2) m² e idade média de 3,8 (±1,5) meses. Todos foram submetidos a circulação extracorpórea (CEC) com avaliação nos tempos 10, 30, 60, 120, 180 e 240 minutos, obtendo-se os valores de taxa de transferência de oxigênio (TTO2) e de taxa de transferência de gás carbônico (TTCO2), hemoglobina sérica (HBS) e livre (HBL), plaquetometria, leucometria e taxa de transferência de calor. RESULTADOS: Houve adequadas TTO2 e TTCO2. A lesão da maioria dos elementos figurados do sangue foi insignificante, sem alterações dos níveis de HBS, HBL, plaquetas e o número de leucócitos diminuíram com o tempo. A troca de calor foi efetiva (p < 0,05). CONCLUSÃO: O oxigenador de membrana infantil OXM1500, testado em ovinos, mostrou-se com capacidade adequada de oxigenação, remoção de gás carbônico e pequena alteração da hemoglobina e plaquetas, com diminuição do número de leucócitos de forma esperada. O trocador de calor acoplado ao oxigenador foi eficaz nas variações de temperatura.

OBJECTIVE: To analyze the security and efficacy of a new membrane oxygenator, the so-called OXM - 1500. METHODS: From May 2005 to September 2006, six sheep of Santa Inês breed (five male and one female, respectively) were studied. The average body weight was 14.1 (±5) kg, body surface 0.6 (±0.2) m² and a mean age 3.8 (±1.5) months. All of them were submitted to extracorporeal circulation (CEC) with evaluation at 10, 30, 60, 120, 180 and 240 minutes. The following values were obtained: values of oxygen transference (TTO2) and carbon dioxide transference (TTCO2), haemoglobin (HBS) and free haemoglobin (HBL), the score of platelets and of leucocytes, and heat transference rate. RESULTS: TTO2 and TTCO2 were adequate. Lesion of the majority formed blood elements was insignificant; there no modifications in HBS, HBL levels; platelets and leucocytes decreased over time. Heat exchange was effective (p < 0.05). CONCLUSIONS: The membrane OXM - 1500 infant oxygenator, tested in sheep, showed adequate oxygenation capacity, CO2 removal capacity, and small alteration of haemoglobin and platelets without significant decrease of leucocytes, as expected. Heat exchanger connected to the oxygenator was efficient in temperature changes.

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Newer oxygenators with the latest technologies are designed to attenuate the immune response, including lymphopenia, prompted by cardiopulmonary bypass (CPB) in cardiac surgery. We evaluated the effect of CPB, comparing an oxygenator with a venous-arterial shunt and a conventional oxygenator with regard to lymphocyte's early activation and apoptosis induction and its implications in post-CPB lymphopenia. Patients undergoing coronary artery bypass graft surgery with CPB, using either a conventional oxygenator or one with a venous-arterial shunt, had blood samples drawn at anesthetic induction (baseline); the beginning and end of the CPB; and at 6, 12, and 24 hours after surgery. Analysis by flow cytometry was undertaken to assess the expression of lymphocyte surface markers (CD3+, CD25+, CD26+, CD69+) and apoptosis (annexin V). Twenty patients were studied; 10 used a conventional oxygenator, and 10 used an oxygenator with venous-arterial shunt. Postoperative lymphopenia (50% decrease), 35% increased expression of CD69+, and 56% decrease in annexin V were significant comparing baseline to 24 hour value, similarly in both groups. Early activation (expression of CD69+) and degree of apoptosis (expression of annexin V) of lymphocytes after CBP in cardiac surgery was similarly observed in both types of oxygenators. The observed lymphopenia after CPB does not appear to be secondary to apoptosis.

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