title: Comparison of intrathoracic and intra-abdominal measurements of central venous pressure.
abstract: BACKGROUND
  Complications can arise from standard intrathoracic central venous pressure (CVP) measurements in critically ill, mechanically ventilated patients. We have assessed the feasibility of catheterisation by the femoral route to measure CVP in the abdomen (ACVP). We compared measurements by the standard jugular or subclavian route (TCVP) with simultaneous ACVP measurements by the femoral route.
  
  
  METHODS
  Between June, 1994 and May, 1995, we recruited 20 critically ill adult patients with various disorders; all patients already had a TCVP line in situ. We placed a femoral catheter in the inferior vena cava close to the right atrium under electrocardiographic guidance. The catheter position was confirmed (and corrected if necessary) by chest radiography. CVP was measured from both sites hourly for 6 h. Positive end-expiratory pressure, mean airway pressure, and intra-abdominal pressure were recorded simultaneously.
  
  
  RESULTS
  One patient was excluded because radiography showed that the catheter position was incorrect. For 133 paired measurements of ACVP and TCVP in the remaining 19 patients, the mean difference was 0.45 mm Hg (SD 0.89: 95% Cl 0.30-0.60); the limits of agreement were -1.33 to 2.23 mm Hg (-1.63 to 2.53). We found a small tendency for the difference between ACVP and TCVP to increase as positive end-expiratory pressure and mean airway pressure increased; the difference was statistically, but not clinically, significant.
  
  
  CONCLUSIONS
  Our study showed that for clinical purposes CVP can be measured by a femoral catheter placed in the abdominal inferior vena cava near the right atrium. This approach can replace standard TCVP measurements in critically ill, mechanically ventilated patients.
authors.affiliation: Department of Anaesthesia and Intensive Care, Prince of Wales Hospital, Chinese University of Hong Kong, Sha Tin, New Territories, Hong Kong.
authors.forename: G M
authors.initials: GM
authors.lastname: Joynt
authors.forename: C D
authors.initials: CD
authors.lastname: Gomersall
authors.forename: T A
authors.initials: TA
authors.lastname: Buckley
authors.forename: T E
authors.initials: TE
authors.lastname: Oh
authors.forename: R J
authors.initials: RJ
authors.lastname: Young
authors.forename: R C
authors.initials: RC
authors.lastname: Freebairn
mesh_terms: D000005:Abdomen; D000328:Adult; D000368:Aged; D001795:Blood Pressure Determination / Q000379:methods*; D002405:Catheterization, Central Venous / Q000379:methods; D002496:Central Venous Pressure; D016638:Critical Illness; D005260:Female; D006801:Humans; D007601:Jugular Veins; D008297:Male; D008875:Middle Aged; D013350:Subclavian Vein; D013909:Thorax; D014682:Vena Cava, Inferior