Central Venous Oxygen Saturation for Estimating Mixed Venous Oxygen Saturation and Cardiac Index in the ICU: A Systematic Review and Meta-Analysis

Abstract

Objectives: The objectives of our systematic review and meta-analyses were to determine the diagnostic accuracy of central venous oxygen saturation (Scvo 2) in estimating mixed venous oxygen saturation (Svo 2) and cardiac index in critically ill patients. Data Sources: A systematic search using MEDLINE, Cochrane Central Register of Controlled Trials, and Embase was completed on May 6, 2024. Study Selection: Studies of patients in the ICU for whom Scvo 2 and at least one reference standard test was performed (thermodilution and/or Svo 2) were included. Data Extraction: Individual patient data were used to calculate the pooled intraclass correlation coefficient (ICC) for Svo 2 and Spearman correlation for cardiac index. The Quality Assessment of Diagnostic Accuracy Studies-2 and Grading Recommendations Assessment, Development, and Evaluation tools were used for the risk of bias and certainty of evidence assessments. Data Synthesis: Of 3427 studies, a total of 18 studies with 1971 patients were identified. We meta-analyzed 16 studies (1335 patients) that used Svo 2 as a reference and three studies (166 patients) that used thermodilution as reference. The ICC for reference Svo 2 was 0.83 (95% CI, 0.75–0.89) with a mean difference of 2.98% toward Scvo 2. The Spearman rank correlation for reference cardiac index is 0.47 (95% CI, 0.46–0.48; p < 0.0001). Conclusions: There is moderate reliability for Scvo 2 in predicting Svo 2 in critical care patients with variability based on sampling site and presence of sepsis. There is limited evidence on the independent use of Scvo 2 in predicting cardiac index.