MMCTS
(June 28, 2005). doi:10.1510/mmcts.2004.000570
Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure
Laser resection of lung metastasis
Axel Rolle*,1 and
Arpad Pereszlenyi1
Department of Thoracic and Vascular Surgery, Coswig Specialized Hospital, Centre for Pneumology, Academic Teaching Hospital of Dresden University, Neucoswiger Str. 21, 01640 Coswig/Dresden, Germany
* Corresponding author: * Tel.: +49-3523-65115; fax: +49-3523-65103. E-mail: dr.rolle{at}fachkrankenhaus-coswig.de
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Summary
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Presentation of the laser resection technique for metastatic lung diseases: a new Nd:YAG 1.318 nm wavelength laser system enables the thoracic surgeon to extend indication and include a larger number of patients for pulmonary metastasectomy. This parenchyma-saving technique allows removal of a significantly higher number of lung nodules in comparison to conventional techniques (stapler, clamp resection). The novel laser system consisted of a high performance Nd:YAG laser emitting the 1318 nm wavelength exclusively up to a power of 40 W, thin flexible quartz fibers (400 µm) with low water content and a four-lens focusing handpiece. Description of laser system, the technique of laser resection, together with an overview of the literature is presented.
Key Words: Laser resection • Lung metastasis • Lung parenchyma-saving resection
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Introduction
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History
In 1985, after establishing a 1064 nm Nd:YAG laser for standard endobronchial interventions [1], LoCicero reopened the debate on the use of lasers in open thoracic surgery as well [2, 3]. However, since his CO2 laser is a pure absorption or cutting laser, it proved inadequate for lung surgery and thus could not establish itself in this medical discipline. As a result, a number of medical centers in the United States, Japan and Europe began experimenting with 1064 nm Nd:YAG lasers, using bare fibers and sapphire tips to perform superficial resections [2,3,4,5,6, 7,8,9]. As Table 1 shows, all of these teams achieved only low patient-loads and published no further results, mainly because the technical difficulties posed by the available 1064 nm lasers could not be overcome without further basic research. To date, our working group remains the only one that has systematically combined laser-technological basic research with animal-experimental research on lung tissue determinants, all aimed at developing a laser system specifically suitable for use on lung tissue [4, 10, 11]. Results of our research achieved in this field are presented in this work.
Scientific background
Due to its parenchymal tissue having a typical water content of 80% but a very low tissue density (just one fifth of the liver parenchyma), a very low heat capacity and a variable air content, the lung is an ideal organ for photothermal laser applications (Schematic 1). Therefore, resecting lung parenchyma requires a laser with a powerful coagulation capability in addition to excellent cutting properties, given the high vessel density. After all, the surgeon must always expect fistulae and increasing bronchopulmonary leaks, particularly when dissecting lung parenchyma, the more so the deeper one works down in the central direction. Comparing the absorption behavior of different lasers in water, one gets an absorption curve rising steeply in several stages, beginning at 1000 nm in the near infrared range and ending at 105 times the base value for the Er:YAG laser [12,13,14]. Such high absorption means that the applied energy is immediately transformed into tissue vaporization (= cutting), with the result that no significant coagulation occurs (as evidenced by the CO2 laser). Consequently, both the Er:YAG and CO2 lasers are unsuitable for use on the lung parenchyma.
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Schematic 1 Laser parameters and lung tissue determinants. The most important tissue determinants are: 80% water content, low tissue density of 0.15 g/cm3, and a high shrinkage capacity due to the air content of the alveoli.
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The same reasoning applies to the holmium laser, which becomes unsuitable at a wavelength of 2100 nm because once again absorption becomes so dominant at this point that sufficient coagulation of the lung parenchyma is no longer guaranteed. Thus, the Nd:YAG laser remains the only promising laser for further development with a view to using it on the lung parenchyma. So back in 1988, we started testing the second wavelength of the Nd:YAG laser (1318 nm) in animal experiments, based on the knowledge that the 1318-nm wavelength significantly differs from the standard (1064 nm) wavelength by its ten times higher absorption in water but still offers sufficient laser light scatter, due its proximity to the beginning infrared spectrum, to satisfy the vital coagulation requirement as well (see Graph 1). Our hopes materialized soon. After just a few tests it became clear that the 1318 nm wavelength provided in fact the intended combination effect – cutting capability plus coagulation capability – so perfectly as could not be achieved with the 1064 nm wavelength [4,10]. As a welcome side-effect, we also found strong lung tissue shrinkage, which provides two additional advantages: mechanical reinforcement of the coagulation effect, and fistula sealing far into the central lobe region. In fact, the surfaces coagulated and sealed off through defocused irradiation with the 1318 nm laser withstand artificial ventilation pressures of up to 25 cm H2O. Obviously, this beats all known hemostyptics and tissue glues several times over. For its coagulation and sealing attributes see Video 1.
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Graph 1 Schematically simplified representation of the absorption spectrum of water (according to Bayly). The diagram exhibits the 1064 nm and the 1318 nm wavelengths of the Nd:YAG laser as well as the ten times higher absorption capacity of the laser wavelength.
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Video 1 Sequence on 1318 nm Nd:YAG laser's unique coagulation and sealing attributes.
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Description of our laser system, its technical parameters
The average efficiency of a primary 1064 nm Nd:YAG laser is approximately 3%. The energy efficiency of the 1318 nm emission wavelength is only 34% that of the primary 1064 nm wavelength. In order to achieve sufficient laser output power at 1318 nm, for lung parenchymal dissection, the system's efficiency must be increased to 5%.
The following design features were incorporated to develop a 1318 nm commercial design Trumph (formerly Hüttinger Medizintechnik, Umkirch, Germany) and Martin companies (MMCTSLink 37). The second wavelength is first generated by adapted reflection of the laser mirrors. High beam quality allows coupling into thin (less than 0.6 mm) optical quartz fibers with minimum losses. For flexible transmission to the area of application, special water-free quartz fibers are required as laser light absorption in water is 10 times higher at the 1318-nm wavelength [12, 15]. A four-lens focusing handpiece was developed to concentrate the laser light and allow manual manipulation of the beam onto lung tissue to keep the working-point focus in the tissue at 4 mm while avoiding heat generation in the focusing handpiece. The extremely high laser power density of 24 kW/cm2 allows fast and precise cutting with simultaneous coagulation and sealing of lung tissue. A high performance smoke evacuation system eliminates the vaporization fumes which are unavoidable during parenchyma dissection with this laser (Photo 1).
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Photo 1 Components of modern laser equipment for the application on lung tissue (1318 nm wavelength, 40 W power output, beam quality, energy efficiency, high performance smoke evacuation system, 0.4 mm diameter of fibre, focusing handpiece, flexible quartz fibers/low water content/).
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Surgical technique
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Laser metastasectomy is performed via anterolateral thoracotomy (staged 3 to 4 weeks, if bilateral) after fulfilling the standard indication criteria for pulmonary metastasectomy (histologically confirmed primary tumor after its radical resection or its fully controlled stage). Preoperative evaluations are the same as for routine thoracic intervention; including history physical examination, chest computed tomography (CT), pulmonary function tests, and bone scan. If signs or symptoms are suggestive, head CT is also obtained. Patients with identified extrapulmonary metastasis are excluded from surgery.
Technique, indication and possibility to save lobes is demonstrated on a case report. A 72-year-old male patient with a history of radically resected parotid cancer was referred to our Institute. Three central metastases: two on the left and one – the largest – central metastasis on the right side can be seen on the CT and X-ray picture, respectively (Photo 2). As for his age and characteristics (location, size) of the central metastases, the patient was refused at many thoracic centers as inoperable. Lower lobe lobectomy on the right, and upper lobe resection on the left side, were considered to be too risky for the patient.
The new 1318 nm Nd:YAG laser system offers a unique opportunity to perform the procedure parenchyma-saving and lobe-sparing. Therefore, we decided to perform the operation on this patient. We started on the left side. The intraoperative situation on the next photograph can be seen: pulmonary artery is mobilized on vessel loop; the upper vein lies next to the central, 30 mm great metastasis (Photo 3). The laser resection of this metastasis was then performed. In the next figure (Photo 4) the situation immediately after the laser resection is presented. Video 2 also shows a similar case with a centrally localized metastasis, however, a smaller one (10 mm). The intraoperative situation – its close relation to segmental pulmonary vein – can be easily recognized.
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Photo 3 Intraoperative view: laser resection of 30 mm central metastasis localized in left upper lobe. Intraoperative situation: pulmonary artery is mobilized on vessel loop.
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Photo 4 Intraoperative view: hemostatic laser resection under excellent visual conditions down to the segmental artery level.
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Video 2 Sequence on laser resection of central lung metastasis localized in left upper lobe. The intraoperative situation – its close relation to segmental pulmonary vein – is demonstrated.
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The procedure followed by a resection of second metastasis (localized in Segment I). After completing the resection, a laser-necrosis ‘tumor bed’ (Photo 5) was treated in the following manner: Exposed bronchial branches at the segmental level were oversewn with absorbable suture (4-0 Vicryl, MMCTSLink 38) and segmental vessels ligated. The lung architecture and orientation was reconstructed following each nodular resection by reapproximating the visceral pleura with a running absorbable suture (4-0 Vicryl) (Video 3). This technique avoided distortion of the lung tissue to allow consistent orientation and palpation of the initially noted lung nodules (Photo 6). At the end of the procedure, the resected lung is re-insuflated by a standard way in accordance with the routine thoracic surgical practice (see also Video 3).
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Photo 5 Intraoperative view: laser resection of second, peripheral, smaller metastasis (localized in Segment I) left.
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Video 3 Sequence on laser resection of peripheral 20 mm lung metastasis localized in left upper lobe (Segment I). The management of segmental arterial and bronchial stumps together with re-insuflation of colapsed lung are presented here.
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Photo 6 Intraoperative view: reconfiguration of the left upper lobe with continuous suture of the pleura visceralis.
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After 4 weeks, the patient underwent the laser intervention on the right side. The initial intraoperative situation with vessel-loop on the interlobar pulmonary artery branches for lower lobe is seen on the next photograph (Photo 7). As for the size of the large metastasis (80 mm), more than a one and a half segment of lower lobe (Segment VI and VIII) had to be removed. The videos show all details of this intervention (Videos 4 and 5). As already mentioned, in the center of the laser-necrosis, ligature of segmental arterial and bronchial stumps are routinely performed as well as the visceralization of the resected lung. For the segmental arterial and bronchial stumps ligature see Video 3.
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Photo 7 Intraoperative view: laser resection of right lower lobe segments with an 80 mm large metastasis (vessel-loop is on the interlobar pulmonary artery branches for lower lobe).
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Video 4 Sequence on laser segmental resection of central 80 mm lung metastasis localized in right lower lobe – First part (laser resection).
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Video 5 Sequence on laser segmental resection of central 80 mm lung metastasis localized in right lower lobe – Second part (management of laser necrosis ‘tumor bed’ and visceralization).
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By performing the metastasectomy in the above-described way, it was possible to save more than 2/3 of the patient's lower lobe and to operate on both lungs by a laser parenchyma-sparing manner. For the patient's postoperative lung-functional results, see Table 2; for his postoperative chest X-ray, see Photo 8. The patient is now six years after the procedure and is in good condition with a full physical activity, living free of metastases.
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Photo 8 Postoperative chest X-ray of the demonstrated case. The situation after the laser lung metasectomy: typical scars on the right side basal and on the left apical, perihilar.
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Results
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From January 1996 (when we started the 1318 nm Nd:YAG laser interventions) to December 2002, we performed lung laser resections in 215 patients. The results of the first 100 patients were already evaluated and published elsewhere [16].
There were 94 males and 121 females in the age range from 20 to 81 years (mean 60.7 years). The main indications for laser lung resections included lung metastases of the following primaries: renal carcinoma in 63 cases, colorectal in 58 and breast cancer in 19 cases. In the remaining 75 cases laser resection was performed for metastases of bronchogenic carcinoma (n=14), malignant melanoma (n=9), sarcomas (n=11), head and neck carcinoma (n=15) and for metastases of other less frequent ones (n=26) (Table 3). The overall number of removed metastases was 1440 (6.7 per patient, ranged 1 to 124).
There was no perioperative mortality. Postoperative complications included prolonged air-leak in one and intrathoracic (intraparenchymal) bleeding in a further case. Follow-up was completed for all patients for a median of 31 months. Overall survival for complete curative resection (n=152; 70.7%) was 82% at 1 year, 66% at 3 years and 30% at 5 years (Graph 2).
Multiple lung metastases present a serious and challenging problem with increasing incidence for thoracic surgeons. In the lung metastasis management a sig-nificant role belongs to laser lung-parenchyma-saving resection. Laser resection may expand the scope of surgical treatment for pulmonary metastases, allowing more complete resection. Indications for laser resection may expand to include patients who are not considered ideal candidates for lung metastasectomy because of poor residual lung function or multifocal pulmonary disease. The new 1318-nm Nd:YAG laser for resection of pulmonary metastases demonstrates a significant influence on conservation of tissue during metastasectomy and appears to minimize complications.
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Footnotes
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1 Drs Rolle and Pereszlenyi disclose that they have a financial relationship with Trumph Co., Germany 
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References
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Summary
Introduction
