Can mixed venous hemoglobin oxygen saturation be estimated using a NICO monitor?
ABSTRACT We hypothesized that mixed venous hemoglobin oxygen saturation (SvO2) can be estimated by calculation from CO2 production, cardiac output, and arterial oxygen saturation measured using a noninvasive cardiac output (NICO) monitor (Novametrix-Respironics, Wallingford, CT).
Twenty-three patients undergoing aortic aneurysm repair underwent SvO2 monitoring using a pulmonary artery catheter and cardiac output monitoring using a NICO monitor. The estimated SvO2 value calculated from NICO monitor-derived values was compared with the SvO2 value measured using a pulmonary artery catheter. The accuracy of this estimation was analyzed with Bland-Altman method. The ability of this estimation to track the change of SvO2 was also evaluated using correlation analysis to compare the changes of estimated SvO2 and measured SvO2.
The bias +/- limits of agreement of the estimated SvO2 against measured SvO2 was -2.1% +/- 11.2%. The change of estimated SvO2 was modestly correlated with the change of measured SvO2.
SvO2 derived from the values measured by the NICO monitor cannot be used interchangeably with the values measured spectrophotometrically using the pulmonary artery catheter. More refinement is required to obtain more reliable estimate of SvO2 less invasively. However, large changes of SvO2 may be detected with this method and can be used as a precautionary sign when the balance between oxygen supply and demand is compromised without inserting a central venous catheter.
- Chest 04/2006; 129(3):507-8. · 5.85 Impact Factor
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ABSTRACT: To compare the course of continuously measured mixed and central venous O(2) saturations in high-risk patients and to evaluate the impact of various factors that might interfere with reflection spectrophotometry. Prospective, descriptive study in the interdisciplinary ICU of a university hospital. 32 critically ill patients with triple-lumen central vein catheters, including 29 patients requiring pulmonary artery catheterization. The accuracy of fiberoptic measurements was assessed by comparison to reference co-oximeter results at regular intervals. We examined the effect on measurement accuracy of physiological variables including hematocrit, hemoglobin, pH, temperature, and the administration of various solutions via central venous catheter. Continuous parallel measurements of SvO(2) and ScvO(2) were performed in patients with each type of catheters over a total observation time of 1097 h. ScvO(2) values were more accurate and stable than in vitro oximeter measurements ( r=0.96 from 150 samples, mean difference 0.15%, average drift 0.10%/day) and was not significantly affected by synchronous infusion therapy or by changes in hematocrit, hemoglobin, pH, or temperature. ScvO(2) values closely paralleled SvO(2), whether measured in vitro ( r=0.88 from 150 samples) or in vivo ( r=0.81 from 395,128 samples) but averaged about 7+/-4 saturation percentage higher. ScvO(2) changed in parallel in 90% of the 1,498 instances in which SvO(2) changed more than 5% (over an average of 43 min). Continuous fiberoptic measurement of central vein O(2) saturation has potential to be a reliable and convenient tool which could rapidly warn of acute change in the oxygen supply/demand ratio of critically ill patients.Intensive Care Medicine 09/2004; 30(8):1572-8. · 5.26 Impact Factor
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ABSTRACT: Carbon dioxide insufflation during laparoscopic surgery may interfere with the accuracy of the cardiac output value measured by the NICO2 system. The authors simultaneously measured cardiac output by the thermodilution method and by the carbon dioxide rebreathing technique during laparoscopic adrenalectomy in a patient with a nonfunctional adrenal tumor. There was a strong correlation between the cardiac output values measured by the two methods. This case report suggests that the carbon dioxide rebreathing technique can be used to monitor cardiac output during laparoscopic surgery.Anesthesia & Analgesia 06/2005; 100(5):1381-3, table of contents. · 3.30 Impact Factor