Over the past 15 years, abdominal surgery has transformed from long, deep incisions that expose internal cavities to keyhole openings through which pass lighted cameras, clippers, and tiny suture devices. After minimally invasive surgery, patients often heal more quickly and can return to their daily activities much sooner than if they had undergone traditional open surgery. Robotic systems now remove hand tremors and provide three-dimensional (3D) images of the surgical site.
Despite these advances, minimally invasive surgery has yet to become a common procedure for many abdominal surgeries. Cost, a steep learning curve for surgeons, and in some cases, longer equipment set-up times keep laparoscopy and robotic surgery from widespread use. Cases that are more complex or involve tight, twisty surgical sites remain a challenge for the long, stick-like tools used during minimally invasive procedures. Only 30% of colon cancer operations, for example, are performed laparoscopically. Visualizing the surgical site also requires insertion of a camera that a surgical assistant must continually move to keep the instruments in view on a monitor in front of the surgeon.
To address these issues, researchers from Columbia University, New York, have created a surgical platform that incorporates nimble movement and 3D visualization of the surgical field. The insertable robotic effector platform (IREP) weighs just over 8 kg and includes two snake-like arms that move with the ease of a human finger. A camera module nestled between the arms provides 3D visual feedback. Housed in a 15-mm sheath, the entire system slides into a natural body opening or small incision and unfolds after placement in the body.
Once unfolded, the IREP becomes the eyes and hands of the surgeon. Because the camera is mounted directly between the right and left arms, the automated camera system replicates human vision and allows the surgeon to see landmarks and other components as if the surgeon were performing open surgery. Surgeons manipulate the arms intuitively using a small console on the bedside.
Specialized software developed by Peter Allen, professor of computer science at Columbia, permits the camera system to automatically track the location of surgical instruments. “The system compensates for moving organs, respiration, and other internal motion,” says Allen. An automated, intelligent system translates into lower surgical costs. In conventional laparoscopy, an assistant must move the camera to follow the surgeon’s tools, and, often, a second assistant must move some of the tools. “By reducing the number of people needed to assist with surgery, you can reduce costs,” Allen says.
The IREP camera is similar to those found in cellphones. The modular design allows the researchers to continually update the system as newer cameras become available. Allen notes that, as the size of the sensor area decreases, more light is needed to produce an image. His group has experimented with light-emitting diodes (LEDs) and fiber optics but has not yet settled on a light source.
The IREP system overcomes the rigidity inherent in minimally invasive surgical tools while providing the precision of much larger, more expensive robotic systems. Conventional laparoscopy tools are long, thin, rigid instruments. Surgeons must learn the optimal angle at which to position the shaft—too small an angle can lead to instrument collisions; too great an angle can limit depth perception. In addition, the cutting and suturing tips on conventional instruments are stiff and cannot move side-to-side or back-and-forth.
IREP's flexible arms are designed to move into tight cavities and provide additional maneuverability because they are completely inside the body. “It’s not enough for surgeons to use a stick with a wrist,” says Nabil Simaan, associate professor of mechanical engineering at Columbia and principal investigator on the project. “We need to provide sufficient dexterity in a confined space. Completely flexible instruments make them inherently safer because they are less likely to puncture tissue.”
"Steering" conventional laparoscopy tools is counter-intuitive, similar to using the rudder of a boat; that is, to move left, an instrument must be pulled right. IREP provides intuitive control of instruments. To move a tool to the right, the surgeon moves the right joystick.
Although the state-of-the-art da Vinci® robotic system provides intuitive control over instruments and the instrument tips move as a human wrist moves, this system is large and takes up most of the operating room. Preparing the system and the patient can add as much as an hour to operating times. Complex abdominal surgery often requires tilting the patient to access various sites. Because da Vinci® is too large to attach to the patient’s bed, assistants must disengage and re-engage the robotic system each time the patient is repositioned. In contrast, the IREP system is portable and can be connected to the patient’s bedside.
In addition to making conventional laparoscopy easier and less costly to perform, IREP will help usher in an emerging approach to surgery: single-port access and natural orifice transluminal endoscopy (NOTES, a surgical approach that eliminates all skin incisions). As their names imply, these new techniques reduce surgical incisions to one or eliminate them altogether. Conventional and robotic laparoscopy require at least three ports, which must be larger than the tools inserted through them.
With IREP, “we’re trying to create enabling technology for this new surgical paradigm,” says Simaan, who is responsible for IREP’s robotic design. The surgical instruments must fit into tight spaces, be nimble, and provide sensory feedback. The researchers are working on adding a force feedback loop that will allow surgeons to feel what they are doing. In conventional operations, a surgeon’s hands provide many details about how much force to use to tie a suture knot or the state of local tissue. Minimally invasive surgery removes that sensory component. “We want surgeons to sense what they’re doing while intervening,” says Simaan.
In addition to cutting, suctioning, and suturing, the next generation IREP system will provide ultrasound deployment and other sensors to monitor conditions within the body.
Extending Treatment Options
The researchers anticipate testing IREP on patients within the next few years. “IREP offers the potential to make surgery faster and safer because it is done more precisely. It also should increase the number of patients who can have minimally invasive surgery because more surgeons will be able to perform the procedure,” says Dennis Fowler, professor of clinical surgery at Columbia University Medical Center, and the principal clinical investigator on the project.
Fowler anticipates IREP will be easier to learn to use than current laparoscopic techniques because the system provides 3D vision of the entire surgical field and the arms can be easily maneuvered within the body. “It will be just like open surgery, but we will be doing it beneath the skin’s surface. We will regain full mobility through automated, intuitive control.”
Innovative approaches to minimally invasive surgery offer new groups of patients another treatment option. For example, minimally invasive surgery could give older patients a treatment option previously considered too risky. “Since IREP should reduce scarring and trauma response, it may help older, fragile patients tolerate surgery,” says Simaan, adding “we won’t know how well the system will improve health care until we begin using it. We are right at the dawn of a new age.”
This work is supported in part by the National Institute of Biomedical Imaging and Bioengineering (grant number 5R21EB007779-03).
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