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Controle ácido-básico na hipotermia

The acid-base management in hypothermia

Resumos

O emprego da hipotermia profunda tem se constituído, atualmente, numa Importante estratégia para melhoria da qualidade técnica e resultados em cirurgia cardiovascular. A hipotermia reduz os danos teciduais induzidos pela isquemia por diminuir o metabolismo e preservar os fosfatos energéticos. A regulação do pH tecidual durante a hipotermia é fundamental para a manutenção da homeostasia celular, já que a hipotermia induz alterações desse pH pela mudança provocada na constante de dissociação da água. A questão do melhor manuseio dos gases sangüíneos durante a hipotermia induzida tem sido objeto de controvérsia. Duas abordagens têm sido preconizadas para o manejo das alterações iónicas durante a hipotermia. A regulção pH-stat envolve a manutenção do pH constante de 7,40 em todas as temperaturas com ajustes da PaCO2 e a regulação α-stat permite a variação do pH sangüíneo, que aumenta conforme a diminuição da temperatura e o conteúdo total corpóreo de CO2 é mantido constante. Nesta presente revisão a relação entre pH sangüíneo e intracelular e as alterações iónicas induzidas pela hipotermia são discutidas.

hipotermia induzida


Deep hypothermia is a usefull tool to improve technical results in cardiovascular surgery and is nowadays the major strategy used to reduce ischemic injury. Hypothermia reduces metabolism and preserves cellular stores of high-energy phosphates. The regulation of tissue pH during hypothermia is important for cellular homeostasis. Furthermore, hypothermia has important effects on pH by altering the dissociation constant of water and various metabolics intermediates and the question of optimal blood gas management during deliberate hypothermia has been subject of much controversy. Two approaches have been advocated for pH management during hypothermia, the first termed pH strategy, where blood pH is maintained constant at 7,40 at all temperatures with PaCO2 adjustment, and in the second type of regulation, termed α-stat strategy, the blood pH is increased according to decrease in temperature and the total CO2 , content of the blood remain constant. In this present review the relationship between blood pH and intracelular pH and the ionic alterations induced by hipothermia are discussed.

hipothermia, induced


ARTIGOS ORIGINAIS

Controle ácido-básico na hipotermia

The acid-base management in hypothermia

Walter José Gomes; Ênio Buffolo

Da Disciplina de Cirurgia Cardiovascular da Escola Paulista de Medicina

Endereço para separatas Endereço para separatas: Walter José Gomes Rua Botucatu, 740 04023-062, São Paulo, SP, Brasil

RESUMO

O emprego da hipotermia profunda tem se constituído, atualmente, numa Importante estratégia para melhoria da qualidade técnica e resultados em cirurgia cardiovascular. A hipotermia reduz os danos teciduais induzidos pela isquemia por diminuir o metabolismo e preservar os fosfatos energéticos. A regulação do pH tecidual durante a hipotermia é fundamental para a manutenção da homeostasia celular, já que a hipotermia induz alterações desse pH pela mudança provocada na constante de dissociação da água. A questão do melhor manuseio dos gases sangüíneos durante a hipotermia induzida tem sido objeto de controvérsia. Duas abordagens têm sido preconizadas para o manejo das alterações iónicas durante a hipotermia. A regulção pH-stat envolve a manutenção do pH constante de 7,40 em todas as temperaturas com ajustes da PaCO2 e a regulação α-stat permite a variação do pH sangüíneo, que aumenta conforme a diminuição da temperatura e o conteúdo total corpóreo de CO2 é mantido constante. Nesta presente revisão a relação entre pH sangüíneo e intracelular e as alterações iónicas induzidas pela hipotermia são discutidas.

Descritores: hipotermia induzida, em cirurgia cardíaca.

ABSTRACT

Deep hypothermia is a usefull tool to improve technical results in cardiovascular surgery and is nowadays the major strategy used to reduce ischemic injury. Hypothermia reduces metabolism and preserves cellular stores of high-energy phosphates. The regulation of tissue pH during hypothermia is important for cellular homeostasis. Furthermore, hypothermia has important effects on pH by altering the dissociation constant of water and various metabolics intermediates and the question of optimal blood gas management during deliberate hypothermia has been subject of much controversy. Two approaches have been advocated for pH management during hypothermia, the first termed pH strategy, where blood pH is maintained constant at 7,40 at all temperatures with PaCO2 adjustment, and in the second type of regulation, termed α-stat strategy, the blood pH is increased according to decrease in temperature and the total CO2 , content of the blood remain constant. In this present review the relationship between blood pH and intracelular pH and the ionic alterations induced by hipothermia are discussed.

Descriptors: hipothermia, induced, in heart surgery.

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Recebido para publicação em 4 de agosto de 1993.

Trabalho realizado na Disciplina de Cirurgia Cardiovascular da Escola Paulista de Medicina. São Paulo, SP, Brasil.

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  • Endereço para separatas:

    Walter José Gomes
    Rua Botucatu, 740
    04023-062, São Paulo, SP, Brasil
  • Datas de Publicação

    • Publicação nesta coleção
      17 Fev 2011
    • Data do Fascículo
      Set 1993

    Histórico

    • Recebido
      04 Ago 1993
    Sociedade Brasileira de Cirurgia Cardiovascular Rua Afonso Celso, 1178 Vila Mariana, CEP: 04119-061 - São Paulo/SP Brazil, Tel +55 (11) 3849-0341, Tel +55 (11) 5096-0079 - São Paulo - SP - Brazil
    E-mail: bjcvs@sbccv.org.br