One in 15 people undergoing robot-assisted prostate, kidney or bladder surgery develops a nerve injury related to pressure from positioning on the operating table, a new study suggests.

Patients on the table getting those types of robotic surgery need to be tilted steeply - with their head by the floor and their feet in the air - to give the surgeon better traction, researchers explained.
“When somebody is in that position, there’s a chance they could slide down - it’s like a big ramp,” said lead author Dr. Tracey Krupski, from the University of Virginia School of Medicine in Charlottesville.

“When you slide, you then could be pulling, or having the drag on some of the nerves. It’s like a constant pulling on the muscle.”

Earlier this month, the Food and Drug Administration announced it would be taking a closer look into safety reports regarding da Vinci surgical robots, made by Intuitive Surgical. The robots cost about $1.5 million each.

For the new study, Krupski and her colleagues reviewed records from 334 robot-assisted urology procedures done at their institution in 2010 and 2011. Those included prostate, kidney, adrenal gland and bladder surgeries.

A total of 22 patients - between six and seven percent - woke up with a positioning injury after their procedure, including weakness, numbness or immobility in the hands or feet. More than half of the injuries resolved within a month, but five lasted more than six months, the study team reported in The Journal of Urology.

Patients were more likely to be hurt during longer procedures: surgeries without a positioning injury lasted four hours, on average, compared to five and a half hours for those in which a person was injured.

Krupski said the new findings shouldn’t raise the alarm over robotic surgery safety.

“I don’t think it means that we need to stop doing it,” she told Reuters Health. “The benefits of a robotic approach far outweigh the six percent chance that we saw this happen.”

Doctors and nurses can try to prevent the injuries by paying close attention to what’s happening to their patients during surgery, she said, and going in to check on their positioning and slightly readjusting them when necessary.

“I think the issue of careful patient positioning and avoiding nerve injury is something that’s there with every patient,” said Dr. Myriam Curet, a surgeon at Stanford University in Palo Alto, California, and chief medical advisor for Intuitive Surgical.

“When you’re putting a patient in a steep position, those issues are heightened,” she told Reuters Health, adding that some non-robotic surgeries require that type of positioning as well.

“I think it’s part of the discussion that any surgeon has with their patient about what the risks of surgery are.”

Krupski agreed the most important message from her study is simply making patients aware of the possibility of nerve injury - so they know what’s going on if it does happen to them.

“You tell the patients that, ‘You might transiently wake up with one of these things that the vast majority of the time goes away,’” she said.

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SOURCE: The Journal of Urology, online March 4, 2013.

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Positioning Injuries Associated with Robotic-Assisted Urologic Surgery

Results
Out of 334 operations, 22 positioning injuries (6.6%) were documented. Thirteen (59.1%) injuries resolved within one month, four (18.2%) resolved between one and six months, and five (22.7%) persisted beyond six months. We found operative time (p<0.0001), in-room time (p<0.0001), and ASA class (p=0.0033) were significantly associated with injury.
Conclusions
Positioning injuries are under-recognized in robotic-assisted urologic surgery and may persist beyond six months. Consideration must be given to counseling patients about the risks of positioning injuries, especially for long operations. Patients with multiple medical co-morbidities (ASA Class 4) are particularly at risk for these injuries.

  James T. Mills,
  Michael B. Burris,
  Daniel J. Warburton,
  Mark R. Conaway,
  Noah S. Schenkman,
  Tracey L. Krupski