title: Accuracy of a mixed venous saturation catheter during acutely induced changes in hematocrit in humans.
abstract: 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.
authors.affiliation: Department of Anesthesiology, Erasmus University, Rotterdam, The Netherlands.
authors.forename: E C
authors.initials: EC
authors.lastname: van Woerkens
authors.forename: A
authors.initials: A
authors.lastname: Trouwborst
authors.forename: R
authors.initials: R
authors.lastname: Tenbrinck
mesh_terms: 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*
chemical_list: D006454:Hemoglobins; D010100:Oxygen