COMPARISON OF INTRATHORACIC AND INTRAABDOMINAL MEASUREMENTS OF CENTRAL VENOUS-PRESSURE

Background Complications can arise from standard intrathoracic central venous pressure (CVP) measurements in critically ill, mechanically ve ntilated patients. We have assessed the feasibility of catheterisation by the femoral route to measure CVP in the abdomen (ACVP). We compare d 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 patient s 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 positio n 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 reco rded simultaneously. Findings One patient was excluded because radiogr aphy showed that the catheter position was incorrect. For 133 paired m easurements of ACVP and TCVP in the remaining 19 patients, the mean di fference was 0.45 mm Hg (SD 0.89; 95% CI 0.30-0.60); the limits of agr eement were -1.33 to 2.23 mm Hg (-1.63 to 2.53). We found a small tend ency for the difference between ACVP and TCVP to increase as positive end-expiratory pressure and mean airway pressure increased; the differ ence was statistically, but not clinically, significant. Interpretatio n 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.