Saturação venosa central e mista de oxigênio no choque séptico: existe diferença clinicamente relevante?

Abstract

Introduction: Central venous oxygen saturation (SvcO 2) has been proposed as an alternative for mixed venous oxygen saturation (SvO 2), with a variable level of acceptance according to available data. This study aimed to evaluate possible differences between SvO 2 and SvcO 2 or atrial venous saturation (SvaO 2), with emphasis on the role of cardiac output and their impact on clinical management of the septic patient. Methods: This is an observational, prospective study of patients with septic shock monitored by pulmonary artery catheter. Blood was obtained simultaneously for SvcO 2 , SvO 2 and SvaO 2 determination. Linear correlation (significant if p≤0.05) and agreement analysis (Bland-Altman) were performed with samples and subgroups according to cardiac output. Moreover, agreement about clinical management based on these samples was evaluated. Results: Sixty one measurements from 23 patients were obtained, median age of 65.0 (49.0-75.0) years and mean APACHE II of 27.7±6.3. Mean values of SvO 2 , SvcO 2 and SvaO 2 were 72.20±8.26%, 74.61±7.60% and 74.64±8.47%. Linear correlation test showed a weak correlation between SvO 2 and SvcO 2 (r=0.61, p<0.0001) and also between SvO 2 and SvaO 2 (r=0.70, p<0.0001). Agreements between SvcO 2 /SvO 2 and SvaO 2 /SvO 2 were-2.40±1.96 (-16.20 and 11.40) and-2.40±1.96 (-15.10 and 10.20), respectively, with no difference in the cardiac output subgroups. No agreement was found in clinical management for 27.8% of the cases, both for SvcO2/SvO 2 and for SvaO2/SvO 2. Conclusion: This study showed that the correlation and agreement between SvO 2 and SvcO 2 is weak and may lead to different clinical management.