title: Comparison of central venous pressure and venous oxygen saturation from venous catheters placed in the superior vena cava or via a femoral vein: the numbers are not interchangeable.
abstract: OBJECTIVE
  To compare venous pressure and haemoglobin oxygen saturation measured from a catheter in the superior vena cava (SVC) with a catheter inserted via the femoral vein, and to assess the agreement of these measurements. To assess the effect of intra-abdominal pressure and intrathoracic pressures on these measurements.
  
  
  METHODS
  Prospective study of patients in an adult intensive care unit, Alfred Hospital, Melbourne, Australia.
  
  
  METHODS
  Central venous pressure (CVP), femoral venous pressure (FVP), venous haemoglobin oxygen saturation in the SVC (SO₂C) and via the femoral vein (SO₂F), agreement between these measures using the Bland-Altman method, and the effect of intra-abdominal pressure and intrathoracic pressure.
  
  
  RESULTS
  43 patients were included; the mean bias for FVP -CVP was 1.05 mmHg (95% CI, 0.30-1.79 mmHg), with limits of agreement of -3.79 to 5.89 mmHg (95% CI, -5.08 to 7.18 mmHg). The bias for SO₂F -SO₂C was -3.21 (95% CI, -6.33 to -0.10), with limits of agreement of -22.43 to 16.01 (95% CI, -27.81 to 21.39). Intra-abdominal pressure had a significant (P < 0.01) effect on both the FVP and on the difference (FVP -CVP).
  
  
  CONCLUSIONS
  This study demonstrates poor agreement between CVP and FVP and between SO₂C and SO₂F and that the measurements taken from these two sites are not interchangeable clinically.
authors: Intensive Care Unit, Alfred Hospital, Melbourne, VIC, Australia. cgroombridge@doctors.org.uk
authors: Christopher J
authors: CJ
authors: Groombridge
authors: Darrel
authors: D
authors: Duplooy
authors: Brandon D
authors: BD
authors: Adams
authors: Eldho
authors: E
authors: Paul
authors: Warwick
authors: W
authors: Butt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002405:Catheterization, Central Venous / Q000379:methods*; D002496:Central Venous Pressure; D005260:Female; D005268:Femoral Vein; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D011446:Prospective Studies; D015203:Reproducibility of Results; D014682:Vena Cava, Inferior; D055815:Young Adult
chemical_list: D010100:Oxygen