Accuracy assessment for three fiberoptic pulmonary artery catheters for SvO2 monitoring

To compare values of SvO2 obtained by reflectance spectrophotometry continuous monitoring with those obtained from blood samples measurements by transmission spectrophotometry (Co-Oximetry). Values of SvO2 recorded by three pulmonary artery catheters for continuous monitoring, SAT1, SAT2 and Oximetrix3 (OX3), were compared in a prospective manner to those measured on blood samples by a Co-Oximeter, using the statistical analysis of Bland and Altman. Adult intensive care unit in an University Hospital. 37 patients admitted for acute respiratory failure and/or shock who required hemodynamic monitoring. The bias (average under- or overestimation) was small for all comparative measurements: +1.3, -0.2 and +1.0 sat% for SAT1, SAT2 and OX3, respectively. However, limits of agreement were only acceptable for SAT2 (-8.3 to +7.9 sat%) and OX3 (-6.7 to +8.6 sat%), but not for SAT1 (-23.3 to +25.9 sat%). No significant drift during 24 h was found with the three catheters. However, in vitro calibration was only found acceptable for SAT2 and OX3. The results were not influenced by the numbers of wavelengths of the device (2 for SAT1 and SAT2, and 3 for OX3) nor did they correlate with any of the hemodynamic and biochemical variables tested. For usual monitoring in the ICU, SAT2 and OX3, gave SvO2 values which are in acceptable agreement with SvO2 measured on blood samples by Co-Oximetry.