Bronchoscopic Utilization of the Nd:YAG Laser for Obstructing Lesions of the Trachea and Bronchi

Symposium on Laser Surgery

Bronchoscopic Utilization of the Nd:YAG Laser for Obstructing Lesions of the Trachea and Bronchi Michael Unger, M.D. *

The recent review of cancer statistics published by the American Cancer Society' shows a disturbing pattern regarding lung carcinomas. Of all cancers diagnosed in 1984, lung carcinoma will account for 22 per cent of all cancers in men and 10 per cent of all cancers in women. According to the same data, the highest mortality rate will also occur from this disease: 35 per cent in men and 18 per cent in women. Additionally, it is predicted that the incidence of lung carcinoma in women will surpass breast carcinoma. In terms of numbers, 153,400 people will be diagnosed with lung carcinoma in 1984 and 126,150 will die of it this year. Unfortunately, many of these patients will succumb due to respiratory failure, which in large part could be due to an obstruction of the tracheobronchial tree, leading to suffocation. Recent technological developments, however, indicate new horizons and eventually the possibility of the earlier detection of lung cancer. 4, 5 At the same time, the introduction of lasers in medicine and surgery has expanded our therapeutic armamentarium and provided us with new palliative therapeutic tools'"!'; at present, the most promising one is the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. The utility of the laser is dependent on its physical characteristics and the resulting interreaction with tissues." The infrared wavelength of the Nd:YAG laser (1060 nm) permits in-depth penetration due to increased scattering effect inside the tissues. The extent of this penetration will also depend on chromatic characteristics, local temperature, and ability to dissipate heat. The "heatsink" effect in large part will depend on the local blood flow. It is also very important to remember that the whole process of "lasering" living tissues is a dynamic one. It is clear, then, that at a certain point in the procedure, the ratio of absorption and scattering of the laser beam in the tissue can be reversed, thus reducing in-depth penetration *Associate Chief, Pulmonary Section, Presbyterian-University of Pennsylvania Medical Center, and Clinical Assistant Professor of Medicine, University of Pennsylvania School of Medicine, Philadelphia; and Co-Director, Institute for Applied Laser Surgery, Bala Cynwyd, Pennsylvania

Surgical Clinics of North America-Vol. 64, No.5, October 1984

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and replacing it by high absorption in the carbonized tissue, culminating in vaporization. 8 Our experimental work as well as our clinical observations have shown us that lasers not only have immediate thermal effects but also delayed photobiologic ones (Fig. 1). Part of the tissues exposed to the appropriate laser beam will be immediately destroyed due to evaporation of water and vaporization (Fig. 1, tracing A). However, local generation of heat and the effect of coagulation of the blood supply will produce a reduction in tissue activity (Fig. 1, tracing B), and eventually its destruction with time. A different example of this mechanism is the interaction between the photosensitizers, as, for example, hematoporphyrin derivative (HPD) and the specific wavelength resulting in the release of radical oxygen and eventual tissue death. Other tissues might respond to a given wavelength with some structural changes, reducing their activity (for example, reducing their tensile strength), but continue to live for a prolonged period of time (as shown in the schematic in Fig. 1, tracing C). If these changes are in the direction of increased activity (that is, biostimulation), they should follow Figure 1, tracing F. In the event of only temporary suspension of normal activity, or of biostimulation, these effects can be represented by Figure 1, tracing D or E. It is obvious, then, that clinical utilization of lasers should take all these events into consideration and dictate the appropriate technique. In the case of the endobronchial utilization of the Nd:YAG laser, we are basically benefiting from the thermal effects (Fig. 1, tracing A and B). The basic technique consists of in-depth coagulation and reduction of blood

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Figure 1. Diagram of effects of lasers over time and regarding normal tissue activity. For more complete explanation, see text.

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supply to the treated area. Further applications of the laser energy eventually result in evaporation of water, culminating in vaporization. However, adjacent parts of the obstruction that were exposed to the scattered laser energy, although not removed immediately, remain affected, which leads to local necrosis and removal of the nonviable tissues. Therapeutic goals should be guided by several parameters, such as malignant versus benign lesions, tracheal and mainstem airways versus peripheral bronchi, and fiberoptic versus rigid bronchoscopy.

MALIGNANT VERSUS BENIGN LESIONS As reported by various European, 7, 12 Japanese, 14 and American medical centers, 10, 13 the majority of lesions treated with the Nd:YAG laser are malignant. Undoubtedly, this is related to the fact that despite many medical advancements, we have not significantly affected the mortality curves of lung carcinomas. In the first 18 months of utilization of this technique at our institution, we have treated 89 patients. Eighty of these patients presented with various malignant neoplasms, which included primary lung and metastatic endobronchial lesions. All of them were very symptomatic and nonsurgical candidates. It is important to remember that in these cases the Nd:YAG laser was used only as a palliative therapy; thus the goals were limited. The effectiveness of the treatment should not be judged only on the basis of subjective evaluation or observation of increased bronchial lumen. These patients undergoing the laser procedure as the treatment of "last resort" invariably believe that in view of the overall situation the results are positive, since this is their only hope for improvement-a major placebo effect. There should then also be correlating objective parameters, as, for example, radiographic improvement (Fig. 2), amelioration of pulmonary ventilation-perfusion ratio (Fig. 3), and improved oxygenation and pulmonary functions (Fig. 4). We recommend the following classification of the immediate results: excellent results, when there is complete removal of the endobronchial obstruction with obvious improvement in the objective parameters correlating with significant symptomatic amelioration; fair results, when there is only partial removal of the obstruction and concomitant objective and symptomatic improvement; and poor results, when, despite extensive coagulation and debulking, the lumen could not be restored although there was complete control of hemoptysis. Based on these criteria, in our experience with malignant lesions we obtained excellent results in 39 patients (49 per cent) and fair results in 24 patients (30 per cent); only 17 (21 per cent) of the patients did not respond to the Nd:YAG laser therapy. These data are comparable with those of Dumon et al., 7 who judged 47 per cent of patients to have good responses, 40 per cent, fair results, and 13 per cent, poor results. Their criteria, however, did not clearly include objective parameters. Looking retrospectively at the long-term effect, we found that, although this mode of therapy is not affecting the overall statistics of lung carcinoma, the palliative effects were sometimes remarkable, allowing comfortable survival of up to 10

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Figure 2. A, Patient with docum e nted squamous cell carcinoma that is obstructing the left mainstem bron chus , produ cing atelectasis and feve r. B, The same patient a few hour; later aft e r treatm ent with th e Nd:YAC laser and reopening of th e lum e n. C, Patient's chest radiograph at hospital discharge. Patient is comfortable and afebrile.

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POST POST Figure 3. A, Ventilation, and B, perfusion lung scans of a patient with obstructing lesion of right mainstem bronchus before and after treament with Nd:YAC laser. Tumor was emanating from the right upper lobe bronchus, which could not be completely reopened.

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Figure 4. Flow volume loops of a patient with squamous cell carcinoma localized on the carina. A, Before therapy with Nd:YAG laser. B, After therapy.

months. However, a precise quantification of the "quality of life," in spite of various techniques used, is very difficult to assess. The prognosis and the treatment goals for patients with benign lesions are obviously very different. In most cases, however, if the laser therapy is not sucessful, there is usually still the option of an open surgical procedure. Such lesions include benign tracheobronchial tumors, which are rare; more frequently treated lesions are tracheal stenosis secondary to trauma, intubation, or tracheostomy. These lesions could also be life threatening and require rapid response. In this field, the European workers, in particular the group in Marseilles, published data on their extensive experience. The results are very encouraging, but it is also obvious that the technique of laser utilization has to be modified, as fibrotic or granulomatous tissues react differently to the Nd:YAG laser beam than a very vascular malignant type of tumor. It also seems that secondary effects, as, for example, biostimulation or suppression, might play an active role in this field, necessitating more advanced studies of dosimetry. In these situations, the combination of the Nd:YAG laser with its mainly coagulating effect, and the CO 2 laser, which is an excellent cutting tool, could be particularly beneficial when appropriate nontoxic fibers are developed for transmission of the CO 2 laser.

TRACHEA AND MAINSTEM BRONCHI VERSUS MORE PERIPHERAL AIRWAYS As expected, most of the life-threatening endobronchial obstructing lesions are localized in the main airways (Figs. 2 and 5). As the goal in the case of malignant tumors is palliative, it becomes obvious that removal of a peripheral obstructing lesion is fraught not only with increased technical difficulties and risks of complications, but also does not make much sense

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Figure 5. A, Patient presenting with almost total obstruction of the opening of the right mainstem bronchus by squamous cell carcinoma. B, Patient after completion of Nd:YAG laser therapy.

physiologically, since only minor changes in the V/O ratio can be affected. However, in rare cases of a tumoral obstruction leading to postobstructive pneumonia or abscess formation in a debilitated patient not responding to antibiotics, the opening of the lumen and drainage might be salutary; the usage of laser therapy for a more peripheral lesion could be justified, regardless of the fact that no significant V/O improvement is anticipated (Fig. 6). Partially obstructing lesions with a visible free bronchial wall and visible lumen are technically much easier to approach and are treated more successfully. It is also in these types of lesions that the best results are being achieved. Conversely, a total obstruction of a main bronchus requires a much more careful approach. Overall, the success rate in total obstruction is in the range of 30 to 50 per cent versus almost 100 per cent success in well-delineated and only partially obstructing endobronchial or endotracheal lesions. It is also important to ascertain that there is no ipsilateral involvement of the pulmonary artery, as improvement of ventilation without corresponding improvement of perfusion will result in pyrrhic victory.

FLEXIBLE VERSUS RIGID BRONCHOSCOPY Although the European groups 7, 12 strongly advocate the usage of the rigid bronchoscope, we have performed 176 procedures with the fiberoptic bronchoscope and only 24 with the open tube, with a similar rate of success. There is no doubt that, from the standpoint of the operator's comfort and facility of manipulation, the usage of the rigid scope would be our first choice. However, considering the type of patients we have been treating, and the purely palliative goals of this procedure in the case of malignant tumors, the added costs and risks of general anesthesia with the rigid bronchoscopy outweigh its potential benefits of the possibility of handling of massive hemoptysis.

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Figure 6. A, Patient presenting with postobstructive pneumonia and sepsis not responding to antibiotic therapy. B, After re-establishment of drainage via Nd:YAG laser, the sepsis resolved although the massive tumor in the right upper lung remained. The patient died 4 months later from extensive metastasis but was not in respiratory failure.

The only other major complication that can be avoided with the opentube technique is endobronchial fire." In distinction to the flammable coating of the fiberoptic bronchoscope, "steel does not burn." The biggest advantage of the open tube is the ease in rapid debulking of previously coagulated extensive and necrotized tumor tissue. There is no doubt that, in this respect, the procedure is much more tedious in using only the fiberoptic scope. The review of published data regarding usage of the endobronchial Nd:YAG laser and our own experience in more than 200 procedures show that despite the very serious nature of the diseases treated, the rate of complications is not overwhelming. The rate of operative deaths seems to be very small, and the most frequently cited direct laser complications were bleeding and endobronchial fire when using the fiberoptic scope. There were also some reports of postoperative infection after reopening an area of an abscess or pneumonia. Arrhythmias, hypoxemia, and hypercarbia were related more to the anesthetic technique and were seen more frequently when general anesthesia was used."

SUMMARY

The new technique of endobronchial usage of the Nd:YAG laser provides surgeons with an additional tool in the palliative therapy of otherwise untreatable, obstructing malignant tumors. In some instances, it can also avoid the need for a more extensive surgical procedure for benign lesions. The usage of the laser, however, is only one part of an otherwise extensive debulking procedure. The advantage of this technique is underscored by the rapid therapeutic response with relatively low rate of

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complications. Unfortunately, the clinical usage of the laser remains more in the realm of an art or "witchcraft" rather than science. The precise tissue effect cannot yet be quantified, neither can we yet measure the power density or the energy density delivered. Further progress in dosimetry is required to convert this primitive state to a state-of-the-art.

REFERENCES 1. American Cancer Society. Ca-A Cancer Journal for Clinicians. 33(1), 1983; 34(1), 1984. 2. Baldassarre, L.: Thermal effects of Nd:YAG and CO 2 lasers on biological tissues. Boll. Soc. Ital. BioI. Sper., 58, 320-326, 1982. 3. Casey, K. R., Fairfax, W. R., Smith, S. J., et al.: Intratracheal fire ignited by the Nd:YAG laser during treatment of tracheal stenosis. Chest, 84(3):295-296, 1983. 4. Cortese, D. A., Kinsey, J. K., Woolner, L. B., et al.: Clinicial application of a new endoscopic technique for detection of in situ bronchial carcinoma. Mayo Clin. Proc., 54:635-642, 1979. 5. Dougherty, T. J., Kaufman, J. E., Goldfarb, A., et al.: Photoradiation therapy for the treatment of malignant tumors. Cancer Res., 38:2628-2635, 1978. 6. Duckett, J. E., Unger, M., Parr, G. V. S., et al.: General anesthesia for Nd:YAG laser resection of obstructing endobronchial tumors using the rigid bronchoscope. Anesth. Analg., submitted for publication. 7. Dumon, J. F., Rebound, E., Garbe, L., tal.: Treatment of tracheobronchial lesions by laser photoresection. Chest, 81:278-284, 1982. 8. Hofstetter, A., and Frank, F.: The Neodymium-YAG Laser in Urology. Edit. Roche Switz., 1982. 9. Laforet, E. G., Berger, R. L., and Vaughan, C. W.: Carcinoma obstructing the trachea. N. Engl. J. Med., 294:941, 1976. 10. McDougall, J. C., and Cortese, D. E.: Neodymium YAG laser therapy of malignant airways obstruction. Mayo Clin. Proc., 53:35-39, 1983. 11. Strong, M. S., Jako, G. J., Polanyi, T., et al.: Laser surgery in the aerodigestive tract. Am. J. Surg., 126:529-533, 1973. 12. Toty, L., Personne, C., Colchen, A., et al.: Bronchoscopic management of tracheal lesions using the Nd:YAG laser. Thorax, 36:175-178, 1981. 13. Unger, M., and Atkinson, G. W.: Nd:YAG laser application in pulmonary and endobronchiallesions. In Joffe, S. N. (ed.): Neodymium:YAG Lasers in Medicine and Surgery. New York, Elsevier Science Pub. Co., 1983. 14. Yamada, R., Amemiya, R., Ohtani, T., et al.: Indications and complications of Nd:YAG laser surgery via the fiberoptic bronchoscope in cases involving the trachea and major bronchi. In Atsumi, N. (ed.): Laser Tokyo '81. Tokyo, Intergroup Corp., 1981. Pulmonary Section Presbyterian-University of Pennsylvania Medical Center 51 N. 39th Street Philadelphia, PA 19104