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Don’t assess central venous O2 saturation with femoral catheters: study

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) Central venous oxygen saturation (ScvO2) can’t be reliably estimated via catheters inserted through the femoral vein, researchers report in the July issue of Chest

Femoral central venous catheters (CVCs) are common in acute care settings despite institutional efforts to move away from the femoral site,” coauthor Dr. Lakhmir S. Chawla at George Washington University Medical Center, Washington, DC, told Reuters Health by e-mail.

These femoral vein-based catheters are sometimes used instead of subclavian or internal jugular lines for assessing ScvO2, Dr. Chawla and colleagues note in their paper.

But ScvO2 is itself a surrogate for mixed venous oxygen saturation as measured by pulmonary artery catheters. A low ScvO2 is clinically relevant, as the authors point out — but what about measurements with femoral vein catheters?

To learn the answer, the researchers analyzed paired blood samples drawn simultaneously from femoral and nonfemoral CVCs in 39 critically ill patients.

More than 50% of the values diverged by more than 5%, they report.

Next, the researchers invited 800 physicians to respond to an online survey. Of the 150 who answered, more than 35% used femoral central vein catheters more than 10% of the time in their initial management of critically ill patients.

“When these femoral CVCs are utilized,” Dr. Chawla concluded, “our data suggest that the ScvO2 measurement cannot be used interchangeably with ScvO2 measurements from subclavian/internal jugular CVCs.”

Reference:
Femoral-Based Central Venous Oxygen Saturation Is Not a Reliable Substitute for Subclavian/Internal Jugular-Based Central Venous Oxygen Saturation in Patients Who Are Critically Ill
Chest 2010; 138:76