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Ann Thorac Surg 2003;76:2035-2036
© 2003 The Society of Thoracic Surgeons
Division of Cardiothoracic Surgery, One Barnes-Jewish Hospital Plaza Queeny Tower, Suite 3108, St. Louis, MO 63110, USA
e-mail: damianor{at}msnotes.wustl.edu
This paper by Jacobs and colleagues from the University of Leipzig represents another important contribution of this pioneering group to the field of surgical robotics. They are to be congratulated for investigating the limitations of present surgical telemanipulators. This type of investigation is critical for progress in this exciting new field.
Robotically-assisted coronary bypass grafting was introduced over five years ago by this same group. Since that time, numerous groups around the world have performed endoscopic coronary artery bypass grafting using advanced telemanipulator systems [1–3]. Despite substantial progress, the overall adoption of these systems has been disappointing. Their use is still only applicable to highly selected patients with limited disease. Robotic coronary surgery has not moved past a relatively small group of early adopters of this technology. There are a number of reasons for this failure to meet early expectations.
Robotics were introduced in the hope that they would enhance surgical dexterity and enable endoscopic coronary revascularization. These systems potentially improve surgical dexterity by tremor filtration, motion scaling, and the restoration of intuitive movement with endoscopic instruments. Early work focused on procedures performed on the arrested, stopped heart. With the inherent difficulties of operating in a completely endoscopic environment with a closed chest, these procedures were confined to patients with single and double vessel disease. However, with the introduction of beating heart surgery, it became less and less acceptable to subject patients with single or double vessel disease to lengthy and difficult endoscopic procedures with long cardiopulmonary bypass times, when off-pump surgery can be performed quickly in these patients and with almost no risk. This led a number of groups to attempt totally endoscopic, beating-heart surgery [4–6]. The group in Leipzig was a pioneer in these procedures. Unfortunately, endoscopic, beating heart, coronary bypass grafting was difficult. These procedures were long and had high conversion rates. These frustrations have led many investigators to call for the development of parallel technology in order to facilitate endoscopic, closed chest coronary revascularization. This beautiful study suggests why robotics are difficult in the moving environment encountered during off pump surgery.
In their moving model, telemanipulator assistance was significantly slower (2.9 times) than manually performed tasks. More importantly, errors with the telemanipulator system rose significantly from 29.2 ± 16.5 at rest to 84.4 ± 35.3 at 60 beats per minute. These differences were highly significant and the error rate was greater than that seen with the same task performed manually. With movement, robotic systems were not only slower, but less accurate. The authors felt this was due to the addition of a second information processing system in addition to the human brain, and the inertia caused by additional electronic and mechanical parts. As a consequence, the human response time was prolonged, causing a delay in task execution and a degradation of technical performance.
While the model used in this study greatly simplifies clinical surgery, it does provide important insights that can be used to guide future developments of more sophisticated instrumentation. It also clearly points out that surgeons should not blindly accept that robotic systems enhance dexterity. In certain clinically relevant situations, they perform worse than traditional manual instrumentation.
It is encouraging to see the publication of studies rigorously examining the clinical utility of telemanipulator systems. It is only through studies like these that clinicians will be able to refine the use of these systems and industry can develop more sophisticated devices to overcome the shortcomings of the present generation of robotics.
References
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