Effect of myocardial protection and perfusion temperature on production of cytokines and nitric oxide during cardiopulmonary bypass

Abstract

Effect of myocardial protection and perfusion temperature on production of cytokines and nitric oxide during cardiopulmonary bypassEffect of myocardial protection and perfusion temperature on production of cytokines and nitric oxide during cardiopulmonary bypass ABSTRACT Purpose: To investigate the effects of different conditions used during cardiopulmonary bypass (CPB) surgery on accompanying production of cytokine and nitric oxide (NO). Methods: Patients undergoing CPB for the first time were prospectively enrolled and divided into two groups according to CPB parameters performed: i) normothermia (36.5-37°C) with blood cardioplegia (NB group, n=10) and ii) hypothermia (29-31°C) with crystalloid cardioplegia (HC group, n=10). Plasma samples obtained following intubation (baseline), during (5 and 30 min) and after (4 and 24 h) CPB were assayed for cytokines (ELISA) and NO metabolites (Griess reaction). Results: Peak concentrations of interleukin (IL)-6 and IL-8 were reached at 4 h post CPB in both groups, but in the HC group those levels increased earlier and persisted for longer (24 h) compared to baseline (P < 0.05). IL-10 levels also increased at 4 h compared to baseline, but only significantly so in the HC group. NO metabolites were reduced in HC group at all time points compared to baseline (P < 0.05), while no significant differences were detected in the NB group. Conclusion: The association between increased systemic levels of cytokines and reduced NO production in the HC group suggests that different myocardial protection and/or perfusion temperature used during CPB may contribute to the extent of inflammatory response. Key words: Cardiopulmonary Bypass. Myocardium. Perfusion. Nitric Oxide. Cytokines. RESUMOObjetivo: Investigar a hipótese de que diferentes procedimentos durante o bypass cardiopulmonary (BCP) causa diferentes níveis de citocinas (IL) e óxido nítrico (NO). Métodos: Pacientes submetidas a BCP foram prospectivamente estudadas de acordo com bypass realizado sobre normotermia (36.5-37°C) com cardioplegia sanguínea (NB group, n=10) or hipotermia (29-31°C) com cardioplegia cristalóide (HC group, n=10). Amostras de Plasma foram obtidas após a intubação (linha de base), durante (5, 30 min) e após (4, 24 h) o BCP. Os ensaios foram realizados através de ELISA (IL) e metabólitos do NO (reação de Griess). Resultados: Os picos de concentrações de IL-6 and IL-8 estavam aumentados em 4 h pós BCP em ambos os grupos, mas no grupo HC estes níveis aumentaram precocemente e persistiram aumentadas por 24 h, comparado a linha de base (P<0.05). O nível de IL-10 também teve o pico em 4 h, mas estatisticamente significante somente no grupo HC, comparado a linha de base. Os metabólitos do NO estavam reduzidos no grupo HC, em todo o tempo, comparado a linha de base (P<0.05), enquanto nenhuma diferença estatisticamente significante foi detectada no grupo NB. Conclusão: A associação entre o aumento sistêmico dos níveis de citocina e a redução da produção de NO no grupo HC sugere que o tipo de proteção miocárdica e/ou ...

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“…[ 87 ] However, in spite of elevated inflammatory cytokines levels, which are able to induce iNOS activity, hypothermia appears to be associated with decreased NO generation at least until 24 h after the end of CPB. [ 2 88 ]…”

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“…Its peak concentration occurs a few hours after the end of CABG-ECC, with a gradual reduction to normal levels in the following 24 hours 23 . The characteristic release of IL6 and IL8 in ECC has been demonstrated after hypothermic and normothermic surgery, but no increase in TNF-α levels occur in normothermic surgery, the results of TNF-α levels in ECC being still conflicting 20,21,24 .…”

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