AUA 2013: Instrument may overcome problems of magnetic guidance

May 6, 2013

Urologists and engineers have developed an instrument that may improve the adjustment capabilities of a magnetic coupling system used in laparoscopic procedures.

Urologists and engineers have developed an instrument that may improve the adjustment capabilities of a magnetic coupling system used in laparoscopic procedures.

Magnetic Anchoring and Guidance Systems (MAGS), introduced 5 years ago by Jeffrey A. Cadeddu, MD, and colleagues at the University of Texas Southwestern Medical Center, Dallas, can be seen as another technological step toward minimizing trauma and morbidity in laparoscopic procedures. The concept underlying the technology is to reduce the number of ports and incisions associated with a surgical procedure by anchoring surgical instruments, such as cameras, intracorporeally with extracorporeal magnets, just as a bar magnet on one side of a sheet of paper can hold a paper clip in place on the other side.

However, there are challenges with the MAGS equipment design that S. Duke Herrell, MD, of Vanderbilt University Medical Center, Nashville, TN, and his colleagues in Vanderbilt’s School of Engineering are bent on resolving.

Dr. Herrell explained that the current camera system is rendered relatively immobile when anchored by the external magnet and that moving it to change the visual field requires often-forceful manipulation of the patient’s abdominal wall.

To resolve this issue, Dr. Herrell and colleagues are developing a dichotomous segmented instrument. One segment, the tail or anchoring module, consists of two magnets for anchoring, stabilization, and manual rough positioning. The second segment is a camera embedded in a structure called the Local Magnetic Actuator.

“The secondary magnet system can move the camera through a range of about 80 degrees vertically via magnetic force. It simply ‘levitates’ its position,” Dr. Herrell explained.

The system’s function and flexibility was demonstrated in nephrectomies performed in four fresh tissue cadavers (three male, one female). The procedures were successfully conducted by first author Ryan Pickens, MD, MPH, using two ports for working instruments only.

At this stage of development, an assistant remotely controls the camera, but Dr. Herrell said he envisions a system that would be controlled by the operating surgeon, perhaps by a foot pedal. He also anticipates employing advanced camera technology. The authors said they have accomplished their goals and hope to move to a clinical setting within 1 to 2 years.