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Temporary Blood Loss during Anterior Spinal Fusion

"Scalpel." "Forceps." "Retractor." If you've watched any TV, you've probably heard these words on one of the medical shows. If not, you may still recognize them as tools used in the operating room. This study focuses on one of these tools: the retractor. The retractor is used to pull and hold back skin, blood vessels, nerves, or other soft tissues in the area where the surgeon is working.

Doctors are very careful, but the retractors can damage some of these structures. For example when fusing the lumbar spine from the front (anterior fusion), retractors are used to move aside blood vessels in the abdominal area. Is there any damage when this is done? Doctors have seen a loss of blood supply to the leg on the same side as the blood vessel retraction. There are also some changes in nerve signals. Are these factors related?

That's what doctors from the University of Southern California studied. They measured oxygen levels and signals in the spinal cord. They looked for changes after putting on the retractors and then taking them off. And they looked at how long it took these measures to return to normal levels.

More than half the patients had major pressure on the left iliac blood vessel. The researchers think this loss of blood flow stops signals in the nerve roots at the end of the spinal cord. Blood loss to the leg also occurs as a direct result of these changes. Once the retractors are taken off, everything goes back to normal. It doesn't seem to matter how long the retractors cut off the blood supply during the surgery. Most patients recover within eight minutes. Some take as long as an hour.

This was the first study to look at the connection between loss of blood supply in a specific blood vessel and loss of spinal cord signals during anterior lumbar spine fusion. The authors give doctors some guidelines for the use of retractors during this operation based on these results.

References: Salvador A. Brau, MD, FACS, et al. Nerve Monitoring Changes Related to Iliac Artery Compression during Anterior Lumbar Spine Surgery. In The Spine Journal. September/October 2003. Vol. 3. No. 5. Pp. 351-355.

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