Central venous saturation in septic shock: co-oximetry vs gasometry

• Published in: The American journal of emergency medicine Vol. 32; no. 10; pp. 1275 - 1277
• Main Authors: Romero, Carlos M., MD, Luengo, Cecilia, MD, Tobar, Eduardo, MD, Fábrega, Luis, MD, Vial, María Jesús, MD, Cornejo, Rodrigo, MD, Gálvez, Ricardo, MD, Llanos, Osvaldo, MD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2014; Elsevier Limited
• Subjects: Aged; Agreements; Blood Gas Analysis - methods; Catheterization, Central Venous; Cohort Studies; Confidence intervals; Emergency; Emergency medical care; Female; Fiber optics; Hospitals, University; Humans; Hypoxia - blood; Hypoxia - complications; Hypoxia - diagnosis; Industrialized nations; Intensive Care Units; Male; Metabolism; Methods; Middle Aged; Oximetry - methods; Oxygen; Oxygen - blood; Physiology; Prospective Studies; Reproducibility of Results; Shock, Septic - blood; Shock, Septic - complications; Studies
• ISSN: 0735-6757; 1532-8171
• DOI: 10.1016/j.ajem.2014.07.027

Abstract Objectives Central venous oxygen saturation calculated by gasometry (Gaso-Scv o2 ) is more available than central venous oxygen saturation measured by co-oximetry (Co-oxy-Scv o2 ) in environments with less resources and underdeveloped countries. Therefore, we aimed to determine the agreement between Co-oxy-Scv o2 and Gaso-Scv o2 and between central venous oxygen tension measured by gasometry (Gaso-Pcv o2 ) and Co-oxy-Scv o2 , respectively. Design and settings This is a prospective study in a university hospital’s intensive care unit. Patients Sixteen patients were studied during the first 48 hours after diagnosis of septic shock. All patients were intubated, connected to mechanical ventilation, and resuscitated according to the standards of care. Measurements and results One hundred eleven pairs of central venous blood measurements were analyzed both by conventional gasometry and co-oximetry. Bland and Altman analysis between Co-oxy-Scv o2 and Gaso-Scv o2 showed lack of agreement (1.7 [− 10.7, + 14.2]). A Gaso-Scv o2 less than 70% had a positive predictive value of 63% in relation to Co-oxy-Scv o2 , and its negative predictive value was 90% with 20% false-positives and 5% false-negatives. The area under the receiver operator characteristic curve of Gaso-Pcv o2 to discriminate a Co-oxy-Scv o2 greater than or equal to 70% was 0.87 (confidence interval, 0.80-0.93), and the best cut-off point was a Gaso-Pcv o2 more than 40 mm Hg, (sensitivity, 75%; specificity, 93%). Conclusions The reliability of Gaso-Scv o2 determination during the resuscitation phase of septic shock is not acceptable. There is a good agreement between a Gaso-Pcv o2 more than 40 mm Hg and a Co-oxy-Scv o2 greater than or equal to 70%. Our results suggest that given these limitations, Gaso-Scv o2 results should be interpreted with caution, helped by Gaso-Pcv o2 measurements and in context with other perfusion parameters.