Continuous monitoring of gastric intraluminal carbon dioxide pressure, cardiac output, and end-tidal carbon dioxide pressure in the perioperative period in patients receiving cardiovascular surgery using cardiopulmonary bypass

Objective: To verify the hypothesis that the gastric intraluminal Pco₂ (Pgco₂) changes independently of the change in cardiac output (CO) during and after cardiovascular surgery using cardiopulmonary bypass (CPB), and that the elevation of Pgco₂ affects the patients' morbidity. Design: Prospective, noninterventional study. Setting: Medical/surgical intensive care unit and operating theater of a university hospital. Patients: Sixteen adults patients receiving elective cardiovascular surgery using CPB. Interventions: None. Measurements and Main Results: After induction of anesthesia, the patients were fitted with a gastric tube equipped at the tip with a CO₂ sensor (ion-selective field effect transistor) that can continuously measure real-time Pgco₂, and a pulmonary artery catheter capable of monitoring continuous CO (CCO) and end-tidal CO₂. Data from the devices was uploaded to a personal computer every 2 mins until the catheter was pulled off based on clinical judgment (Pgco₂ values were blinded to everyone except the investigator). One patient expired as a result of multiple organ failure subsequent to sepsis, and postoperative morbidity assessed by the peak SOFA (sequential organ failure assessment) score (mean ± SD 6.9 ± 3.5; range, 2-13) was correlated with the peak Pgco₂ during intensive care unit stay (mean ± SD 74.1 ± 30.7 mm Hg; range, 45-169 mm Hg) (p < .01, by regression analysis). The peak Pgco₂ during surgery (mean ± SD 71.1 ± 18.1 mm Hg; range, 44-115 mm Hg) had no correlation with the postoperative morbidity. From analysis of CCO before, during, and after returning from the above 60 mm Hg of Pgco₂, Pgco₂ changed independently of CCO. Conclusions: Pgco₂ changed independently of CCO, and its postoperative elevation was related to morbidity, even in the group of patients with a good outcome. Continuous monitoring of Pgco₂ is useful for the detection of morbidity and can be expected to help elucidate the pathophysiology of change of Pgco₂.