A comparison of central venous pressure and common iliac venous pressure in critically ill mechanically ventilated patients

Objective: To investigate the possibility of using common iliac venous pressure (CIVP) as an alternative to superior vena cava pressure (SVCP) in mechanically ventilated, critically ill, adult patients. Design: A randomized, blinded comparison. Setting: Multidisciplinary intensive care unit at a university teaching hospital Patients: Twenty mechanically ventilated, critically ill, adult patients. interventions: None. Measurements and Main Results: All patients had a catheter in situ for measuring the SVCP. A new triple-lumen catheter, with a length ranging from 15 to 20 cm, was placed into the common iliac vein via the femoral route. The SVCP and CIVP were simultaneously measured at hourly intervals for 6 hrs. Positive end-expiratory pressure, mean airway pressure, and intra-abdominal pressure were measured at the same time intervals. For 140 paired measurements of CIVP and SVCP in 20 patients, the mean difference was 0.1 +/- 1.06 (So) mm Hg (95% confidence interval -0.10 to 0.25); the limits of agreement were -2.04 to 2.20 mm Hg (95% confidence interval 2.34 to 2.50). Mean airway pressure, intra-abdominal pressure, and positive end expiratory pressure had no measurable effect on the difference between SVCP and CIVP. Serious complications arising from insertion of the catheter through the femoral route were not observed. Conclusion: For clinical purposes, CIVP measured by a catheter of 15 to 20 cm placed through the femoral route is interchangeable with SVCP in mechanically ventilated adult patients. This finding provides an alternative route for assessment of central venous pressure when other routes are not appropriate.