Accuracy of a mixed venous saturation catheter during acutely induced changes in hematocrit in humans.
OBJECTIVE
To determine the accuracy of in vivo mixed venous hemoglobin saturation (Svo2) measurements with a fiber optic thermodilution catheter during acute changes in hematocrit.


METHODS
Comparison of fiberoptic in vivo Svo2 values with in vitro Svo2 values obtained with a multiwavelength spectrophotometer.


METHODS
Operating room in a university hospital.


METHODS
Six consecutive patients who are Jehovah's Witnesses.


RESULTS
Before and after each step of hypervolemic hemodilution and after every 500 mL of blood loss, blood gases were analyzed and hemodynamic, hemoglobin, hematocrit, and in vitro and in vivo Svo2 measurements were made. Hematocrit values were measured in the range of 40% to 18%. Plotting all in vivo Svo2 values (n = 74) against the in vitro Svo2 measurements obtained during the entire study period gives r2 = .86. The accuracy of in vivo Svo2 measurements was not affected by changes in hematocrit or cardiac output. The Svo2 catheter value at the beginning of the study differed from the in vitro Svo2 value by -0.86 +/- 2.56% and at the end of the study period of 8 to 10 hrs by 0.71 +/- 3.04%.


CONCLUSIONS
The accuracy of the studied fiberoptic continuous measuring Svo2 system was not affected by changes in hematocrit or cardiac output. No significant drift in the in vitro Svo2 measurements was observed.
van Woerkens
E C
EC
Department of Anesthesiology, Erasmus University, Rotterdam, The Netherlands.
Trouwborst
A
A
Tenbrinck
R
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005336:Fiber Optic Technology; D006400:Hematocrit; D006438:Hemodilution; D006439:Hemodynamics; D006454:Hemoglobins / Q000032:analysis*; D006470:Hemorrhage / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D055100:Optical Fibers; D010100:Oxygen / Q000097:blood; D013053:Spectrophotometry / Q000379:methods*; D013815:Thermodilution / Q000295:instrumentation*
D006454:Hemoglobins; D010100:Oxygen