Magnetized Ferrofluids Could Prevent High Spinal Block

A new study reports that using local anesthetic mixed with magnetized ferrofluids may provide a new approach to preventing a rare but serious complication of spinal anesthesia.

Developed by researchers at the University of Virginia Health Sciences Center (Charlottesville, USA), the technique involves the addition of a water-based ferrofluid to magnetize the anesthetic fluid. Using the magnetized local anesthetic solution and exterior magnets could help to control the spread of spinal anesthesia during surgical procedures, thus providing a simple but effective additional safeguard against high spinal block. It might also be useful in controlling the spread of anesthetics in other situations; for example, spinal anesthesia on one side of the body.

The researchers also created a simple model of the spine using fluid-filled plastic tubing. They then prepared a local anesthetic solution to which they added a water-based ferrofluid to magnetize the fluid. When a magnet was placed outside the tubing, below the level of the needle, it halted the downward flow of magnetized fluid. In fact, when the magnet was moved, the fluid even moved against gravity. However, the researchers stated that more research is needed before the technique can be applied in patients, with the first question that needs to be answered being the safety of the magnetic fluid. The study was published in the June 2012 issue of Anesthesia & Analgesia.

“With further research, the magnet technique may provide a second means - in addition to gravity - of preventing high spinal block, which occurs when spinal anesthetics spread to the upper portions of the spinal cord,” concluded lead author Robert Thiele, MD, and colleagues of the department of anesthesiology.

High spinal block is a serious, but rare, complication of spinal anesthesia, occurring at a rate of about 0.6 per 1,000 cases. It occurs when injected anesthetics travel too high in the spinal cord, interfering with the spinal cord fibers governing heart function. This can result in sharp drops in heart rate and blood pressure, with a risk of cardiac arrest and death. Anesthesiologists currently prevent high spinal block by modifying the anesthetic dose and by positioning the patient so that gravity distributes the anesthetic to the lower portions of the spinal cord.

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