Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942004000500002
Brazilian Journal of Anesthesiology
Scientific Article

Avaliação da correlação entre o dióxido de carbono expirado e o débito cardíaco em pacientes submetidos à cirurgia cardíaca com circulação extracorpórea

Correlation between end-tidal carbon dioxide levels and cardiac output during cardiac surgery with cardiopulmonary bypass

Karina Takesaki Miyaji; Roberto Iara Buscati; Antônio José Arraiz Rodriguez; Luciano Brandão Machado; Luiz Marcelo Sá Malbouisson; Maria José Carvalho Carmona

http://dx.doi.org/10.1590/S0034-70942004000500002 Braz J Anesthesiol, vol.54, n5, p.625-633, 2004
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Resumo

JUSTIFICATIVA E OBJETIVOS: O CO2 expirado (P ET CO2) reflete, além da ventilação pulmonar (eliminação), a produção de dióxido de carbono (metabolismo) e o fluxo sangüíneo pulmonar (circulação). Quando o metabolismo e a ventilação são constantes, o CO2 expirado reflete o fluxo sangüíneo pulmonar e, desta forma, o débito cardíaco (DC). Este estudo tem como objetivo a avaliação da correlação entre o dióxido de carbono expirado (P ET CO2) e o débito cardíaco em pacientes submetidos à cirurgia cardíaca com circulação extracorpórea (CEC). MÉTODO: Foram estudados 25 pacientes submetidos à cirurgia de revascularização miocárdica com CEC. Após a intubação traqueal iniciou-se a monitorização da P ET CO2. A determinação do débito cardíaco (DC) foi feita por método de termodiluição com o uso de cateter de Swan-Ganz e a PaCO2 foi avaliada através de gasometria arterial. Os parâmetros do estudo foram avaliados em quatro momentos: logo após a indução da anestesia geral; antes da circulação extracorpórea, ao término da circulação extracorpórea e ao final da cirurgia. RESULTADOS: O teste estatístico não demonstrou uma correlação entre o CO2 expirado e o DC, assim como o gradiente de dióxido de carbono arterial e expirado (Ga-eCO2) e o DC. Foi encontrada correlação entre a variação dos valores da P ET CO2, Ga-eCO2 e DC em relação ao basal antes da CEC com perda da correlação após a CEC até o final da cirurgia. CONCLUSÕES: Neste estudo, onde se avaliam pacientes submetidos à cirurgia cardíaca com CEC, as alterações de relação ventilação/perfusão ocorridas ao longo do procedimento são, provavelmente, os fatores determinantes da diminuição da correlação entre o débito cardíaco e o valor de dióxido de carbono expirado.

Palavras-chave

CIRURGIA, MONITORIZAÇÃO, MONITORIZAÇÃO

Abstract

BACKGROUND AND OBJECTIVES: End-tidal carbon dioxide (P ET CO2) not only reflects pulmonary ventilation but also carbon dioxide production (metabolism) and pulmonary blood supply (circulation). During constant metabolism and ventilation, P ET CO2 reflects pulmonary blood perfusion, thus cardiac output (CO). This study aimed at evaluating the correlation between P ET CO2 levels and CO during cardiac surgery with cardiopulmonary bypass (CPB). METHODS: Participated in this study 25 patients submitted to coronary artery bypass grafting (CABG) with CPB. End-tidal CO2 monitoring started after tracheal intubation. Cardiac output was determined by thermodilution with pulmonary artery catheter (Swan-Ganz). Carbon dioxide partial blood pressure (PaCO2) was obtained with arterial blood gases analysis. Studied parameters were evaluated in the following moments: immediately after general anesthesia induction, before cardiopulmonary bypass, at cardiopulmonary bypass completion and at surgery completion. RESULTS: Statistical analysis has not shown correlation between P ET CO2 and CO2, or between P ET CO2-PaCO2 gradient (Ga-eCO2) and CO. There has been correlation between P ET CO2, Ga-eCO2 and CO values variation as compared to baseline values before CPB, with loss of correlation after CPB until surgery completion. CONCLUSIONS: In this study, where patients submitted to cardiac surgery with CPB were evaluated, ventilation/perfusion changes throughout the procedure might have been the factors determining decreased correlation between cardiac output and end tidal CO2.

Keywords

MONITORIZATION, MONITORIZATION, SURGERY

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