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A1233
October 16, 2012
1:00:00 PM - 4:00:00 PM
Room Hall C-E-Poster area
Comparison of Peripheral to Central Venous Oxygen Saturation in Postoperative Cardiac Surgery Patients
Vera Santos, M.D., Bernardo Costa, M.D., Hugo Ferreira, M.D.,Ph.D., Miguel Marques, M.D., João Santos, M.D., Guilherme Mota, M.D., Ricardo Pereira, M.D., Celine Marques, M.D., Ivo Pires, M.D., Hugo Vilela, M.D.
Universitary Hospital of Santa Maria, CHLN, Lisbon, Portugal
Background

Central venous saturation (ScvO2) represents the deoxygenated blood of the upper part of the body and can be used to guide therapy in critically ill patients.1,2 However ScvO2 requires the placement of a central venous catheter which is associated with potential complications. Peripheral venous oxygen saturation (SpvO2) would be technically easier and safer than ScvO2 but the information on the relationship between ScvO2 and SpvO2 is scarce. We prospectively compared ScvO2 and SpvO2 in postoperative cardiac surgery patients at the intensive care unit.

Methods

Twenty-seven postoperative cardiac surgery patients were enrolled in the study. Blood samples were taken simultaneously from central venous lines and peripheral veins at the upper extremity at random points in time. Blood gas analyses were performed to determine ScvO2 and SpvO2. The data pairs were analyzed for correlation (Spearman’s rank correlation) and agreement using Kappa (k) analysis and Bland and Altman analysis corrected for repeated measurements. Values of P < 0.05 were considered statistically significant.

Results

Fifty-two data paired of ScvO2 and SpvO2 were compared. The mean ScvO2 (SD; range) was 64.5 % (12.1; 39.0 to 94.0) and the mean SpvO2 was 64.5 % (28.7; 12.0 to 100.0) (P < 0.0005). Overall there was a moderate correlation between SpvO2 and ScvO2 (r = 0.626; P < 0.0001). There was a poor agreement between the two methods (k = 0.190). The mean (SD) bias (SpvO2-ScvO2) was 2.0 (21.8) % (P < 0.0001) and lower and upper limits of agreement (LOA) were - 40.8 and 44.8 %, respectively. Two of 52 points were outside the LOA.

Discussion

SpvO2 showed a moderate correlation and poor agreement when compared with ScvO2. There was a statistically significant bias and very large LOA between SpvO2 and ScvO2.. We consider that the two methods cannot be used interchangeably and that SpvO2 cannot be used to predict ScvO2 in this sample of postoperative cardiac patients.

References

1. Am J Respir Crit Care Med. 2011 Sep 1;184(5):514-20.

2. Crit Care Clin. 2010 Apr;26(2):323-33.

Copyright © 2012 American Society of Anesthesiologists