Correlation of mixed venous and central venous oxygen saturation and its relation to cardiac index

• Published in: Indian journal of critical care medicine Vol. 10; no. 4; pp. 230 - 234
• Main Authors: Ramakrishna, M, Hegde, Devi, Kumaraswamy, G, Gupta, Ratan, Girish, T
• Format: Journal Article
• Language: English
• Published: New Delhi Medknow Publications and Media Pvt. Ltd 01-10-2006; Jaypee Brothers Medical Publishers Ltd
• Subjects: Analysis; Catheters; Hypoxia; United States
• ISSN: 0972-5229; 1998-359X
• DOI: 10.4103/0972-5229.29841

Background and Aim:The clinical applicability of substitution of central venous oxygen saturation for mixed venous oxygen saturations in monitoring global tissue hypoxia is still a matter of controversy. Hence aim of the study is comparison of paired samples of mixed venous and central venous oxygen saturation and comparison in relation to cardiac index in varying hemodynamic conditions. Materials and Methods: Prospective clinical observation: Postoperative cardiac surgical ITU: 60 adult patients,> 18 years of age of either sex: A PAC was inserted through ® IJV, triple lumen catheter was inserted through ® IJV. Blood samples were taken from distal tip of PAC and central venous catheters. An arterial blood sample was drawn from either radial or femoral arterial line. Measurements: Continuous cardiac output monitoring. Analysis of blood samples for hemoglobin concentration and oxygen saturation. Mixed venous oxygen saturations and central venous oxygen saturations were compared. The study was carried over a period of 30h in the postoperative period and samples were taken at 6h intervals. Patients were classified into three groups as follows depending on the CI: Low (< 2.5 L/m 2 ), medium (2.5-4 L/m2 ), high (>4 L/m2) and correlated with Svo2 and Scvo2 . Results: 298 Comparative sets of samples were obtained. Svo2 was consistently lower than Scvo2 throughout the study period. The difference was statistically significant. By using Bland - Altman plot, the mean difference between Svo2 and Scvo2 (Svo2 -Scvo2 ) was - 2.9% ± 5.14 and confidence limits are + 7.17% and - 12.97%. The co-efficient r is > 0.7 throughout the study period for all paired samples. The correlation Svo2 and Scvo2 with cardiac index in all the three groups were> 0.7. Conclusion: Scvo2 and Svo2 are closely related and are interchangeable. Even though individual values differ trends in Scvo2 may be substituted for trend in Svo2