A 60 year old diabetic arrives at the hospital complaining of sudden visual loss. The ophthalmologist suspects a thromboembolic event in the retinal vasculature. Today’s tools allows the surgeon to routinely visualise the exact vessel that this has occured in. The progress of thrombus is easily documentable, with the inflamatory and necrotic reactions that follow. The cure is clear – remove the clot. Yet thrombolysis is contraindicated in many patients due to the risk of haemorrhagic strokes. Nor is embolectomy possible due to the tiny vasculature involved. There is a frustrating inability to halt the progression to permanent visual loss. Such thromboembolic events are a major cause of blindness in the Western world. Clearly, what is needed are some new tools.
Perhaps a robot could help?
Researchers at the Johns Hopkins Hospital, in the US, are developing robotic solutions for such problems. Although their research will take a few years to enter clinical practice, few realise is that over 50 robots are in use today. Earliest example were in Continental Europe and Japan, and they have enjoyed considerable clinical and commercial success.
There are three main ways that this has happened. Firstly, in some situations, robots can be more accurate and precise in their actions than the human hand.Perhaps the earliest example of this success is RoboDoc.
In 1992 the first operation using the Robodoc Surgical Assistant System was carried out. Used in hip replacements, it tackled the problem of reducing the gap between implant and bone in hip surgery. While a skilled surgeon can achieve gaps of 1 mm, Robodoc approximated the 0.5 mm gap, which matches the growth achievable by the bone with time. Thus it minimized one of the biggest factors of prosthesis failure. Thus it minimized the potential for poyethylene wear debris to enter the bone-cement interface, which is one of the biggest factors of prosthestic failure. So far clinical trials in continental Europe have involved over 6000 operations. These included the Domestic Multi-Center Trial European Trial, led by Dr William L. Bargar at the Berufsgenossenschaftliche Unfallklinik in Frankfurt, Germany. Early results show theatre time to be roughly twice as long as normal operations, while the hospital stay and immediate complication rates are not significantly different. However, from a technical point of view in terms of size and positioning, the robot performance was far superior. Furthermore theatre turnover speed is likely to increase as experience with the tools grows.
Secondly, robots can reach parts that surgeons can’t. The FDA’s approval last year of the commercial sale of computer-controlled robotics for abdominal laparoscopic surgery as well as minimally invasive gallbladder, prostate, colorectal and esophageal procedures opens up the potential of 3.5 million operations a year in the United States. At one million dollars a robot, the da Vinci ™ Surgical System by Intuitive Surgical is the early market leader. Computer Motion has recently released its Zeus system, at $750,000.
These two systems are similar in principle, but different in implementation. The aim is to introduce robot into the operating field through a minimal incision, reaching previously inaccessible areas and allowing easy manipulation. In the UK, the da Vinci system is already in place at Imperial College, London, where it is being used by Professor Ara Darzi. By design, the console is meant to be immersive: the surgeon looks down at a three-dimensional view of the patient’s innards, as picked up by a two-chip charge-coupled device video element in the scope at the end of one of the stainless-steel rods. The element is the same type of chip used in digital
cameras. The result is an improvement over the two-dimensional view afforded by current laproscopic techniques.
By contrast, the ZEUS console is more like a computer workstation: the surgeon sits opposite a vertical screen—available with 3-D stereo imaging using lightweight polarizing glasses. An in-depth display, it turns out, may not be as crucial as the subtle color cues available from monocular high-definition video, especially at 10 times magnification, which is beyond the augmentation afforded by simple optics worn by a nonrobotically assisted surgeon. This system is in use at the Brompton hospital, London.
Thirdly, new machines have been used in the field of percutaneous interventions. Brought to you by the makers of RoboDoc, Neuromate is the first robotic system for use in stereotactic functional brain surgeries. Its current uses include the treatment of Parkinsons Disease, epilepsy, and neurological tumours. To date, it has has been used in over 2,000 neurosurgical cases on patients in the U.S., Europe, Japan, and the Middle East.
So what about our 60 year old patient with visual loss? Professor Russel Taylor is director of the Engineering Research Center for Computer-Integrated Surgical Systems and Technology. His teams at the Johns Hopkins Hospital are active in various areas, including microsurgery. Operating in retinal vasculature with a diameter of 100 microns is simply too difficult by hand. Eugene deJuan is a leading ophthalmic surgeon working in the team. In operations on dogs, he can only achieve a 50% success rate. The robotic system developed at the Center eliminates the tremors of a surgeon’s hand. With this, even a graduate student is able to succesfully manipulate the retinal vasculature.
The UK has some research efforts of its own. Professor Darzi is Director of the Academic Surgical Unit at the Imperial College School of Medicine, St Mary’s Hospital, London. His group is involved in developing sensors for the next generation of tools – haptics.
Haptics is a maturing computer specialty that deals tactile sensory feedback. From the Greek haptikos, meaning to grasp or perceive, it allows the user to “touch” the computer’s data.
Immersion Medical, an American company, is the market leader. They have been selling medical training devices since 1998. Their best selling product, CathSim, provides force-feedback simulation for urinary catheter insertion. Other products train in needle injection, sigmoidoscopy and bronchoscopy. Colonoscopies are next in the pipeline. The tactile feedback relies on combinations of electromagnetic brakes, motors, cables and other devices. This would still be pretty coarse, however, were it not for the visual feedback. Watching the television screen that accompanies every device provides an optical illusion powerful enough to fill in the haptic gaps.
Professor Darzi’s work builds on such achievements. However, where today’s sensors give crude simulations, his team’s research promises greater acuity and realism. This should allow its deployment in the operating theatre.
But the UK is still relatively behind in the deployment of such robots. Professor Darzi believes the major stumbling block is the lack of evidence of clinical efficacy. Such machines are expensive, and they must justify their costs against traditional interventions. As such, he is involved in several of the international clinical trials to answer these questions. However, he still believes there should be more funding in the UK for these trials. Such investment is necessary to avoid falling further behind.
According to Professor Darzi, such systems should reach the mainstream over the next two to three years. Are such robots really better than humans? Professor Taylor is careful to explain that such a choice is not the issue – all of these are additional tools that assist the surgeon in carrying out the operation. In addition, he points out that different evidence exists for different clinical situations. The field is at varying maturity for the procedures available. But of the oldest, RoboDoc, he is clear – “For hip surgery, I would certainly prefer a robot. It is more consistent, safer and does a better job.”
Published May 2001 in Medical Futures magazine