URGEONS once had the ultimate hands-on job: spreading
the rib cage to gain access to the heart, feeling for lumps in
a deflated lung, sewing up blood vessels.
But for some operations, like closed-chest coronary bypass
surgery, doctors now station themselves not by the patient but
at a nearby computer console. With their eyes fixed on a
monitor, they use joystick-like controls to guide robotic
scalpels, scissors and high-resolution cameras that have been
inserted in the patient's body through keyhole-size
However precise and tremor-free these robotic tools are,
though, they lack one attribute that surgeons prize: a
delicate sense of touch.
Robert D. Howe, a professor of engineering at Harvard
University, wants to change that by creating roboticized
instruments that will, among other abilities, palpate internal
"I think that sensory feedback is the key to the next
generation of robotic-assisted surgery," he said. "Current
robots have no sense of touch built into them — everything is
done purely on visual information."
Dr. Howe spoke last month at a symposium on the future of
minimal-access surgery at Columbia University. It was
sponsored by New York-Presbyterian Hospital and the Fu
Foundation School of Engineering and Applied Science at
Minimally invasive surgery — the medical field in which
doctors no longer directly touch or see the tissues on which
they operate — offers advantages. The tiny incisions limit
damage and help speed recovery, and the roboticized
instruments that do the surgeons' bidding can scale down the
doctors' motions, doing precise work in tight spaces without
any hand tremor.
"But the robot can't do everything," said Dr. Michael
Argenziano, who spoke at the conference. Dr. Argenziano, an
assistant professor of surgery at Columbia University's
College of Physicians and Surgeons, is currently testing a
system for closed-chest coronary bypasses.
"The robot is an advanced tool for getting into the patient
through the smallest incisions possible with the least
trauma," he said. "We're going to need a host of ancillary
techniques for working in a closed chest."
Dr. Howe hopes to add fine tactile sensitivity to future
robots' arsenals. "Operating by eye requires attention and it
slows things down," he said. Tactile feedback would make the
robots easier to use and speed surgical procedures.
To that end, Dr. Howe's group has developed a device for
remote palpation that can sense when one area of soft tissue
is harder or rounder than the surrounding tissue. "For
example, the surgeon may know that the lump exists because of
a CAT scan," he said, but in surgery the lung deflates, making
the lump harder to find.
The hidden lump is not a problem in open procedures, in
which surgeons spread the ribs and use their fingers to find
it. But surgeons who work with robotic probes and cameras
inserted through small incisions may have difficulties.
"I've seen surgeons spend 15 minutes finding a lump using a
probe passed through a one-centimeter incision," Dr. Howe
said. "It's like trying to find a pea inside a bowl of jello
Dr. Howe's solution is an engineered stand-in for the
surgeon's palpating fingers. At one end, deep in the body, is
the electronic "fingertip," actually a square matrix of 64
pressure sensors. This fingertip sweeps the interior surface.
When it hits a lump, the pressure rises in some or all of the
sensors, for the lump does not compress the way the
surrounding tissue does.
The other end of the fingertip, which extends outside the
body, is a tactile display of tiny motorized pins that the
doctor's real finger rests against. Each pin on the display
corresponds to one of the 64 sensors at the other end. A
processor translates the pressure detected at each sensor into
the rise and fall of each pin, so the doctor can feel the
contours of the object inside the body.
The device, now only a prototype, is not meant to be a
stand-alone instrument. "The key will be to build these
distributed tactile devices into surgical tools like graspers
and retractors," Dr. Howe said, so that they can be used to
locate hidden matter.
Dr. Michael Mack, a cardiac surgeon and chairman of the
Cardiopulmonary Research Science and Technology Institute in
Dallas who spoke at the conference, said he would welcome
tools that could palpate for minimal-access surgery. "Adding
the ability to feel is a good thing," he said.
But Dr. Mack, who took part in the initial Food and Drug
Administration trials of one roboticized system, said he was
skeptical about the current generation of roboticized systems
for coronary bypass operations. "Eventually computerization
will make it better," he said. But he said that for now,
surgical robots offer few if any advantages.
Mastering such instruments involves a significant learning
curve, he said. "The second and third generations should
address issues that make the systems more friendly."
Dr. Howe said that a sense of touch would be one
improvement to robotic systems. "Surgeons will not have to pay
so much attention to visual cues as they proceed," he said.
"This will leave them extra mental attention for other
Dr. Richard M. Satava, a surgeon and professor at Yale
University who discussed the use of smart instruments at the
meeting, predicted other changes in operating rooms.
He suggested that many scrub nurses, for example, would
eventually be replaced by robotic systems. "No tool will need
to be handed to a robot by a scrub nurse," he said. "There's
not a lot of thinking in handing an instrument to a robot —
that job doesn't have to be done by a person."
Dr. Satava predicts that not only the scrub nurse but also
most of the surgical team will be replaced by robots. "We fly
jet airplanes by wire," he said. "One day we'll do the
equivalent to that in the surgery."