Noninvasive Measurement of Central Venous Pressure

They determined central venous pressure (CVP) by monitoring blood volume changes in the arm in response to externally applied circumferential pressure to the brachial vein. Four monitoring electrodes are spaced along the arm and a blood pressure cuff is placed on top of two of the electrodes near the shoulder. Over the course of a minute, the cuff is partially inflated and deflated allowing the monitoring electrodes to detect changes in blood volume. The data are then sent to a computer that determines the CVP.

Sixteen patients who were undergoing CVP monitoring as a part of their care had non-invasive CVP (NICVP) determined and compared with CVP. NICVP was determined as the cuff pressure noted at the maximum derivative of the forearm volume decrease during deflation. NICVP was then compared to invasively measured CVP taken during the same period. The investigators found the new noninvasive method was as accurate and precise as directly measuring CVP from the catheter. The study detailing the new technique was published in the August 2006 issue of Resuscitation.

"The ability to accurately monitor CVP in a safer, more efficient, noninvasive way will have tremendous patient benefits and enable health care workers to make more rapid treatment decisions,” said co-author Kevin Ward, M.D., an associate professor in the emergency medicine department at Virginia Commonwealth University. "This should ultimately lead to improved patient outcomes and fewer complications.”

Monitoring CVP of a critically ill or injured patient can be essential in determining how well blood is circulating to vital organs and if the heart is failing; but until now, doctors had to thread a catheter through the neck or chest to a point near the right atrium to accurately determine CVP.



Related Links:
Virginia Commonwealth University Reanimation Engineering Shock Center