Ann Thorac Surg 2005;80:1898-1901
© 2005 The Society of Thoracic Surgeons
New technology
Computer-Controlled Stapling System for Lung Surgery
Dominique Gossot, MD
*
,
Albert Nana, MD
Thoracic Department, Institut Mutualiste Montsouris, Paris, France
Accepted for publication February 3, 2005.
* Address correspondence to Dr Gossot, Institut Mutualiste Montsouris, Thoracic Department, 42 Blvd Jourdan, Paris, F-75014 France (Email: dominique.gossot{at}imm.fr).
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Abstract
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PURPOSE: Current disposable hand-actuated staplers may pose reliability problems, especially with respect to the measurement of tissue thickness. We have evaluated a newly developed stapler with a computer-controlled placement of staples.
DESCRIPTION: The SurgAssist system (Power Medical Interventions, New Hope, PA) is comprised of a console that houses a computer, a remote control unit, a flexible shaft, and a cartridge. The remote control unit has two uses: (1) controlling the accurate placement of the cartridge by orientating the tip of the flexible shaft, and (2) controlling the closure of the stapler and the firing. Each cartridge contains a programmed electronic device that triggers the activation of the appropriate program in the main microprocessor. The compression level on the tissue is determined by the computer.
EVALUATION: The system was used in a consecutive series of 38 patients, 26 times during open lung surgery and 12 times during video-assisted thoracic surgery. The following open procedures were performed: three pneumonectomies, 15 lobectomies, three segmentectomies, and five wedge resections. The following video-assisted thoracic surgery procedures were performed: eight wedge resections and four bullectomies for pneumothorax. There was no stapling failure and no complication related to the use of the stapler. During video-assisted thoracic surgery, some ergonomic problems were encountered that will be overcome by redesign.
CONCLUSIONS: The computer-controlled stapling system may significantly improve tissue approximation during open and video-assisted thoracic surgery.
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Introduction
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Mechanical hand-actuated staplers have been used for years for pulmonary resections, either during open or video-assisted surgery. Although some questions about the safety of these staplers were raised as they were introduced into thoracic surgery, the experimental works, controlled trials, and routine clinical use of these staplers have convinced most surgeons that stapling was safer and more convenient than hand suturing.
However, despite the fact that mechanical staplers are widely used, they are still not the ideal tool as several incidents are frequent such as hemorrhage or oozing on the staple line and even partial or complete disruption of staples. During video-assisted thoracic surgery (VATS), the use of endo-staplers raise even more problems. These have a narrower opening and are more fragile, especially when thick tissues have to be stapled. Evaluation of tissue thickness during VATS is a challenge and misjudgements are frequent, leading to disruption of the staple line.
Therefore, the use of a stapling system that can precisely measure tissue thickness and adjust positioning of staples could be a breakthrough in terms of safety. We have used a newly developed stapling system based on a computer-controlled placement of the staples, and we report our preliminary experience.
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Technology
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The SurgAssist system (Power Medical Interventions, New Hope, PA) is comprised of a console that houses a computer microprocessor (Fig 1), a remote control unit (Fig 2), a flexible shaft, and a staple cartridge with or without a knife blade, named the digital loading unit (DLU). The 2-m long flexible shaft is sterile and is connected to the SurgAssist unit. Its current diameter is 14 mm, requiring the use of a 15-mm diameter trocar when used during VATS. The remote control unit is protected by a plastic sterile sheath similar to those used for protecting camera heads during thoracoscopic or laparoscopic procedures. The remote control unit has two uses: (1) controlling the accurate placement of the DLU by orientating the tip of the flexible shaft, and (2) controlling the closure of the stapler and the firing.
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Fig 2. The remote control unit: (1) allows opening and closing of the digital loading unit; (2) the release button allows articulation to recover flexibility; (3) allows the staple firing and cutting once the position of the stapler is correct; (4) activates the processor; and (5) the keypad allows articulation of the stapler head.
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Two types of DLUs are available for thoracic surgery. The first type of DLU is a straight linear cutter with a blue (3.5 mm) or a green (4.5 mm) cartridge (Fig 3), which is available in a 55-mm length. Each DLU contains a programmed electronic device that triggers the activation of the appropriate program in the main microprocessor of the console. It also has an electronic safety lockout function. Contrary to other linear cutters, the movement of the scalpel blade is not directed from back to front but from front to back. This prevents tissue to be pushed away by the progression of the blade, as is frequently observed with conventional linear cutters. The second type of DLU is a right angle linear cutter available in 2 lengths (ie, 30 mm and 45 mm) (Fig 4). Two types of staples are available for the 30-mm right angle stapler (ie, a white vascular and blue-green combination cartridge allowing for in situ staple adjustment based on tissue thickness). Contrary to most right angle staplers, a blade is included in the cartridge and cuts between the staple rows. Another genuine feature of the right angle stapler is its perpendicular orientation to the shaft.
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Technique
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Once the stapler is applied, the system first checks if the tissue thickness is compressed within the firing range of the chosen DLU, with the compression level on the tissue determined by the computer. For instance, when stapling a bronchial stump, the surgeon may hesitate as to whether to use a blue (3.5 mm) or green (4.8 mm) cartridge. With the SurgAssist system, the surgeon may choose whether to use the blue or the green after determining the bronchus thickness and resistance. Information is displayed on the liquid crystal display screen of the console and also by a voice system message notification. The surgeon then fires using the remote control unit. No manual force is applied on the stapler. The DLU is changed if additional applications are needed. With the second generation SLC55, known as the Power Linear Cutter 55 or PLC 55, the DLU may be reused as many as 100 times, and only the cartridge is changed. Should any problem occur, such as excessive thickness or resistance of the tissue, then the surgeon is alerted that the system is out of stapling range.
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Clinical Experience
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The SurgAssist system was used in a consecutive series of 38 patients, 26 times during open lung surgery and 12 times during VATS. The limited number of VATS cases is due to technical reasons detailed as follows. The open procedures that were performed were three pneumonectomies, 15 lobectomies, three segmentectomies, and five wedge resections. The VATS procedures that were performed were eight wedge resections and four bullectomies for pneumothorax.
For vascular stapling, a conventional vascular stapler was used because 2.5 mm staples were not available at the time of this study. The SurgAssist system was used for stapling the main stem bronchus (3 patients), a lobar bronchus (15 patients), parenchyma for wedge resection (13 patients), bullectomy (4 patients), or fissure division (12 patients).
The following points were prospectively recorded: any kind of incident during the procedure, such as hemorrhage on the staple line or disruption, difficulty in handling or maneuvering the device, needing to switch to a conventional stapler for any reason, and any postoperative complication that might have been related to the use of the stapler.
During the open thoracotomy procedures, no incidents were observed. In 2 patients, an accurate positioning of the right angle stapler on the main stem bronchus was not possible because of DLU design, and there was a need to switch to a conventional terminal anastomosis stapler. There was no air leak. One patient was reoperated on for hemothorax related to bleeding of a bronchial artery outside of the staple line. This was not considered as a complication of the SurgAssist system, but as a surgical mistake.
During the eight VATS cases, maneuvering the SurgAssist system was often difficult, and we had to give up in 3 cases and use a conventional endo-stapler. The main concerns were the insufficient opening of the linear stapler that made large wedge resections impossible to complete and the flexibility of the shaft. What might indeed have been a benefit in some cases was often a drawback for VATS, because sometimes it prevented loading tissue within the jaws. Furthermore, the distal articulated end of the shaft was too long for most chest cavities. In the VATS group, there was one parenchymal tear that required endoscopic suturing. This was a consequence of the difficulty to engage the stapler jaws on the tissue because of excessive flexibility and insufficient opening. The postoperative course was uneventful and there was no other intraoperative or postoperative complication. These concerns led to the abandonment of the system for VATS, while waiting for modifications that would make the device more reliable and easier to use, such as a larger opening and the addition of a rigid flex shaft extender for better positioning.
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Comment
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Staplers are routinely used in thoracic surgery. They are considered as safer than sutures [1, 2] and help decrease operating time [3]. However, although seldom reported, complications of staplers do exist [4, 5]. Another issue is the choice of staples. It is usually admitted that thin parenchyma or lobar bronchi, or both, must be stapled with 3.5 mm staples, whereas thick parenchyma or main stem bronchi, or both, require 4.8-mm staples. But there are exceptions, depending on patient (gender, weight) or tissue features, so that surgeons frequently hesitate between the two types of staples. Besides, some authors advocate that the 4.8-mm staples are a better choice for closure of the lobar bronchus except for middle lobe and small women [6], contrary to the generally accepted opinion. Misjudgements may have serious consequences, particularly when dealing with the main stem bronchus. With the development of VATS, correct estimation of tissue thickness and resistance is even more problematic. Because of the lack of tactile feedback, it is frequent to underestimate the tissue thickness leading to incomplete stapling or disruption of staples. Because reaction time is longer than through open surgery, potential hazards of stapling are more stressful during VATS [4]. Even break of the stapler handle may occur if the surgeon does insist and exert excessive force on the handle. Endo-staplers are also used for closure of the bronchial stump during open pulmonary resections because they allow stapling and division by one action and are less cumbersome than other staplers. However, according to Asamura and colleagues [7], stapling failure occurs more often with endo-staplers than with conventional terminal anastomosis staplers.
The SurgAssist system has the advantage of allowing the surgeon to select the appropriate staple height. If the tissue is too thick the system does not allow firing. The staple height is adjusted depending on the reload that is used, whether blue or green, and the selection is based on the thickness of the tissue. The staples are smoothly applied without the need for exerting any force. Another advantage is the genuine movement of the blade from front to back that avoids tissue to be pushed out of the stapler jaws.
With the current version of the SurgAssist system that was used in this study, some limitations were encountered. The flexible shaft should theoretically be an appealing feature that can be very helpful in other fields of surgery, particularly for esophageal and colonic anastomoses [8, 9]. But for lung resection, it was actually a drawback, especially during VATS. This was due to the length of the articulated tip that took too much room inside the pleural cavity. In addition, it is sometimes better to have a rigid shaft when some force must be exerted in order to load the parenchyma properly within the stapler jaws or to turn around the bronchus. This drawback led to temporarily abandon the system during VATS, and a rigid applicator was developed (Fig 5). The design of the right angle stapler where the shaft is perpendicular to the head (and not in line) was also a problem in some cases.
Comparing the cost of this new system to conventional staplers was not our goal. This will need further evaluation once the system has reached its definite aspect. In the second generation, only the cartridges will be disposable. The DLU will be reusable up to 100 firings, which should compete favorably with current disposable staplers that are expensive and lead to significant material waste.
Despite minor shortcomings related to the design of the first version of this stapler, the new system seems to be a real breakthrough compared with the conventional mechanical stapler. Ergonomics and design will be modified in the forthcoming new version, allowing an easier use during VATS procedures. The computer control concept has a lot of potential and may significantly improve tissue approximation.
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Disclosures and Freedom of Investigation
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Part of the equipment (computer, remote control unit, and flexible shaft) used for evaluation was provided free of charge by Power Medical Intervention. No funding was given and the authors have no financial support from the company. Digital loading units were purchased by our institution on the basis of a regular cartridge. Data were recorded and analyzed in an independent manner.
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Disclaimer
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The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.
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References
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- Graeber G, Collins J, DeShong J, Murray G. Are sutures better than staples for closing bronchi and pulmonary vessels Ann Thorac Surg 1991;51:901-904.[Abstract]
- Peterffy A, Calabrese E. Mechanical and conventional manual sutures of the bronchial stumpA comparative study of 298 surgical patients. Scand J Thorac Cardiovasc Surg 1979;13:87-91.[Medline]
- Jungginger T, Walgenbach S, Pichlmaier H. Stapler and manual bronchial anastomosisresults of a consecutive trial series. Langenbecks Arch Chir 1989;374:323-328.[Medline]
- Craig S, Walker W. Potential complication of vascular stapling in thoracoscopic pulmonary resection Ann Thorac Surg 1995;59:1157-1159.
- Mattioli G, Castagnetti M, Leggio S, Jasonnni V. Complications of mechanical suturing in pediatric patients J Pediatr Surg 2003;38:1051-1054.[Medline]
- Takizawa T, Terashima M, Koike T, Akamatsu H. Selection of staple for closure of the lobar bronchus Nippon Kyobu Geka Gakkai Zasshi 1996;44:1717-1720.[Medline]
- Asamura H, Kondo H, Tsuchiya R. Management of the bronchial stump in pulmonary resectionsa review of 533 consecutive recent bronchial closures. Eur J Cardiothorac Surg 2000;17:106-110.[Abstract/Free Full Text]
- Martin Z, Sweeney K, Borey T. Peroral and transgastric esophageal anastomosis with flexible remote-control stapler (SurgASSIST) Surg Laparosc Endosc Percutan Tech 2004;14:230-233.[Medline]
- Waage A, Gagner M, Feng J. Early experience with computer-mediated flexibe circular stapling technique for upper gastrointestinal anastomosis Obes Surg 2003;13:88-94.[Medline]
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R. F. Heitmiller
Invited commentary
Ann. Thorac. Surg.,
November 1, 2005;
80(5):
1902 - 1902.
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Abstract
Introduction
