title: [Correlation between end-tidal carbon dioxide levels and cardiac output during cardiac surgery with cardiopulmonary bypass.].
abstract: OBJECTIVE
  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.
authors.affiliation: Faculdade de Medicina, Universidade de São Paulo.
authors.forename: Karina Takesaki
authors.initials: KT
authors.lastname: Miyaji
authors.forename: Roberto Iara
authors.initials: RI
authors.lastname: Buscati
authors.forename: Antônio José Arraiz
authors.initials: AJ
authors.lastname: Rodriguez
authors.forename: Luciano Brandão
authors.initials: LB
authors.lastname: Machado
authors.forename: Luiz Marcelo Sá
authors.initials: LM
authors.lastname: Malbouisson
authors.forename: Maria José Carvalho
authors.initials: MJ
authors.lastname: Carmona