Intraluminal tumor growth in the airway may cause atelectasis distal to sites of obstruction and respiratory symptoms. In patients with tracheal involvement, severe symptoms usually occur after the development of high-grade stenosis. Urgent treatment to secure the airway is therefore often required.
During a therapeutic bronchoscopy procedure, a bloodless field is one of the important requirements. To prevent airway bleeding, several procedures have been developed. Endobronchial electrosurgery, defined as the interventional use of high-frequency electrical current under bronchoscopic guidance, has currently become a popular procedure for the bronchoscopist.1–3 Sporadic case reports and institutional experience support the feasibility and safety of this procedure.4–7 The safety of exposing the tracheobronchial tree to high-frequency electrical current remains to be established. Moreover, instruments and accessories suitable for endobronchial electrosurgery have not been standardized although they were described in several reports.5–7 In sharp contrast, gastroscopic and colonoscopic interventions, such as endoscopic mucosal resection and snare polypectomy, have been routinely performed and well established since early 1980s.8,9
In this context, this study was performed to establish the safety of endobronchial electrosurgery for the effective treatment of lesions arising in the tracheobronchial tree.
From August 1998 to April 2000, 37 patients (31 males and 6 females, age 16 to 83 y, average 58 y) underwent endobronchial electrosurgery. All patients gave written informed consent to participate in the study. To be eligible for treatment by endobronchial electrosurgery, patients had to have lesions located in the tracheobronchial tree confirmed by direct visualization. The lesion had to be endobronchial while the extrinsic compression was excluded. If the distal side of the lesion could not be clearly visualized, computed tomographic scans were performed to document normal tracheobronchial structure distal to the obstruction. The depth of lesional invasion was not specified.
All patients were admitted and underwent endobronchial electrosurgery either at the Center for Diagnostic and Therapeutic Endoscopy or at the operating room of each participating center.
Seven doctors who were board certified and members of the Japan Society for Bronchology engaged in this study and conducted endobronchial electrosurgery.
A video bronchoscope with a secure electrical ground (model T240, Olympus, Tokyo, Japan) or a conventional flexible bronchoscope (also electrically grounded) was used. The high-frequency electrocoagulator PSD 10 (Olympus) was used for most procedures, or an equivalent device. Additional tools used included a hot punch biopsy forceps, snare biopsy wire, coagulation tip, and endoscopic electric knife, developed especially for bronchoscopic use and distributed by Olympus. Several sizes of these instruments were available to the operator and were selected according to the characteristics of the lesion. All were designed for 2.1-mm and 2.6-mm instrumentation channels. All procedures required a secure ground circuit.
The strength of the electric current used in this study was based on the results of preliminary studies in swine.10 The maximal power output was determined on the basis of thermally induced changes in tissue and the change in temperature produced by exposure to electric current. To ensure safety, we decided that the power output should not exceed 30 W for punch biopsy, 30 W for snare resection, 20 W for the coagulation tip, and 10 W for the electric knife.10
The goal of this procedure was determined according to the individual situation of each patient. Resolution of airway stenosis and/or resection of intraluminal tumors with minimal bleeding were the primary goal in 36, and control of bleeding from an intratracheal tumor in 1.
All procedures were recorded as bronchoscopic reports and photographic records. Events observed during and after procedure were also recorded. The endobronchial electrosurgery study group evaluated results of the procedures. Successful removal of the airway lesion with minimal bleeding and hemostasis were the criteria of success in this study. Relief of symptoms was evaluated separately.
Thirty-seven patients who met the eligibility criteria were enrolled. The diagnosis was primary lung cancer in 12 patients (including 2 carcinoid tumors), recurrent lung cancer with involvement of the tracheobronchial tree in 10, malignant tumor invading the bronchial tree in 5 (2 metastatic bronchial tumors, 1 esophageal carcinoma, 1 primary osteogenic sarcoma of the lung, 1 malignant tumor), tracheal malignancy in 6, and inflammatory granuloma in 4 (Table 1).
The lesions mainly involved the subglottic region in 4 patients, the trachea in 8, the carina in 3, the right main bronchus in 4, the left main bronchus in 5, the lobar bronchus in 9, and segmental bronchi in 4 (Table 1).
A total of 54 procedures were performed in the 37 patients (1 to 6 procedures per patient). There was no mortality and no major complication associated with endobronchial electrosurgery.
Among 37 patients, 26 complained of respiratory symptoms, such as dyspnea, hemoptysis, and difficulty in sputum expectoration. After endobronchial electrosurgery, improvement of symptoms was observed in 23 patients.
There were 22 patients who showed tumor involvement at various levels of bronchial tree and 15 patients whose diseases were located at subglottic lesion, trachea, and/or carina. Among 22 cases of bronchial diseases, in 12 patients, protrusion of tumors into the airway precluded full study of the distal portion of the bronchial tree. Snare resection or hot punch biopsy of the tumor (or both) was safely and successfully performed, enabling visualization of the distal side of the tumor. Tumors in 2 of these 12 patients subsequently underwent surgical resection. One underwent bronchoplasty, whereas the other, who had a polypoid tumor protruding into the left main bronchus, underwent lobectomy with systematic nodal dissection because there was no apparent invasion at the orifice of the left upper lobe bronchus.
Tools used for endobronchial electrosurgery are shown in Table 2. Although the selection of tools was left to physicians' own choice, there was a unanimous tendency in tools selected. As a result, snare dissector was frequently used for resection of polyps, whereas small polyps are resected by multiple maneuvers of hot punch biopsy forceps. For broad base elevation and circumferential invasion of the tumor, electrocoagulation chip and/or electrosurgical knife were used.
The outcome of electrosurgery was unsatisfactory in 2 of the 37 patients. The first patient had an osteosarcoma arising in the right upper lobe. Atelectasis of the entire right lung was present. Flexible bronchoscopy revealed a large round tumor arising from upper lobe, which occluded the right main bronchus. Snare resection was attempted, but failed owing to the hard consistency of the tumor. Patient underwent pneumonectomy a week later. Pathologic examination revealed a primary osteosarcoma that originated in the right upper lobe growing into the right main bronchus and contained ossified tissue.
The other poor outcome was in a patient with endobronchial bleeding. A coagulation tip was used to control bleeding, but complete hemostasis could not be achieved. This patient had bleeding from the surface of an intratracheal metastasis from an adenoid cystic carcinoma of the tongue. Blood oozed from the tumor surface and covered the luminal surface of the trachea.
Specimens obtained in the study were submitted to pathologic examination. There was minimal evidence of thermal degeneration of tissue when an electric current was applied for less than 1 s. However, an electric current of longer duration caused charring in some specimens, making them unsuitable for pathologic evaluation. In general, less than 1 s of electric current is necessary for hot punch biopsy, whereas several seconds are required for snare resection of endobronchial tumors.
As regard to the power output, we strictly followed the protocol of this study. However, in 1 patient with a large polyp in the upper trachea that occupied 90% of the lumen, an output of 20 W could not resect the thick stalk of the tumor. Resection required an output of 30 W applied for a total of 73.7 s in this patient, whereas in other patients, required time was less than 5 s. Pathologic examination revealed adenoid cystic carcinoma. Segmental tracheal resection with anastomosis was subsequently performed after an interval of 2 weeks. Pathologic examination of the surgical specimen showed degenerative changes of tracheal cartilage with marked fibrosis, indicating thermal effects. These changes were attributed to the prolonged application of electric current. We could examine the thermal effect to the tissue in 2 other patients who underwent surgical resection after electrosurgery. In these 2 patients' specimen, pathologic examination revealed no evidence of thermally induced changes at the resection stump.
Recent development of interventional bronchoscopy has allowed us various modalities to treat endobronchial diseases.3 Among these interventions, some need general anesthesia and/or special equipment. Several techniques such as laser ablation and cryo-ablation can be used to manage obstruction/stenosis of the tracheobronchial tree. Endobronchial electrosurgery is one treatment option, although its safety has not been firmly established.4,11,12 Therefore, we set out to determine whether flexible endobronchial electrosurgery is a safe and reliable procedure when employed by authorized bronchoscopist with strict guidelines. To resolve problems related to safety, we previously conducted animal studies, which showed that high-frequency electric current markedly increases the temperature of tracheal tissue in vivo. (2 s of 30 W gave more than 70°C at bronchial wall) Needle-type coagulators and electrosurgical knives easily penetrate the tracheal wall when applied at a low output, such as 10 W, for half a second.10 From the animal study, we realized that prospective observational study was necessary to establish the safety and effectiveness of endobronchial electrosurgery and define specific indications, thereby defining patients most likely to benefit. Verkindre et al11 reported the morphologic change of tracheo/bronchial wall induced by extensive endobronchial electrocautery in swine. We, therefore organized a study group composed of well-trained bronchoscopists from major hospitals in Japan.
Endobronchial electrosurgery was considered to be indicated for the treatment of intraluminal lesions, including tumors, granulation tissue, and scar tissue. In this study, all operators were board certified by the Japan Society for Bronchology to ensure the use of standardized procedures and the safety of the study participants.
There was no mortality or major morbidity related to endobronchial electrosurgery. The outcome of treatment was satisfactory in 35 of the 37 patients enrolled. There were no adverse events during or after treatment in any patient. We judged the outcome to be poor in 2 cases. One was associated with a large polypoid osteosarcoma containing calcified tissue, occurring in the right upper lobe. This lesion could not be resected with the use of a snare, suggesting that polypoid lesions with calcification should be treated by techniques other than endobronchial electrosurgery. In the other patient with a poor outcome, oozing bleeding from an intratracheal metastasis was not satisfactorily controlled by electrosurgery. The electric current could not be concentrated on the bleeding site to obtain complete hemostasis. The use of an argon plasma coagulator or Nd-YAG laser may have been the treatment of choice in this patient.12
Thermal effect caused by electrosurgery has been studied in clinical setting by Van Boxem's group.6 They studied the thermal effects on normal bronchial wall of patients and described that longer exposure of electrical current cause destructive change around the applied area, although they did not observe perforation of the wall. Throughout this study, no perforation occurred, because we limited the power output to 10 W and duration to 1 s for the electrosurgical knife and coagulation tip. From the several reports, endobronchial electrosurgery has proven safe and effective but the power output and duration of electrocautery has not been clearly stated.3–7,13,14 Our results indicated that endobronchial electrosurgery is a safe procedure, provided that strict guidelines are followed. Endobronchial electrosurgery has several advantages over bronchoscopic laser ablation. High-frequency electric current can be applied to subsegmental bronchi under flexible bronchoscopic guidance. In contrast, laser ablation of lesions located in distal bronchi is sometimes difficult and dangerous, because the walls of such bronchi are thin and easily penetrated by a laser beam.15 Another advantage of endobronchial electrosurgery is the absence of generation of smoke, which could injure the lower respiratory tract. This procedure can be used with other treatment modalities such as cryotherapy.13,16 Endobronchial electrosurgery also costs less than laser therapy, which requires expensive equipment.14,15 Laser ablation, on the other hand, does not require direct contact with tumors and can immediately vaporize obstructions at target sites. However, complications such as hemorrhage,15 mediastinitis,17 intratracheal burns,18,19 and air embolism20 have been reported.
There are possible complications that might occur during endobronchial electrosurgery such as airway fire, electric shock to patients or operators, airway perforation, massive bleeding, and bronchomalacia after thermal injury to the bronchial cartilage.
As regard to airway fire, we performed safety studies in animals. Oxygen concentration is the main factor for the airway fire when high power lasers are used for airway intervention.21 Colt and Crawford22 also studied airway fire caused by argon plasma coagulator. The situation may be the same with endobronchial electrosurgery because we recognized electrical sparks during our animal studies.10,21 To prevent this complication in this study, operators were allowed to use oxygen only when electrical current was not being applied.
Electrical shocks are preventable by ensuring secure electric grounding from the patient's body and the use of insulated equipment.
Airway perforation can be prevented by careful direct observation whenever sharp instruments are used. Massive bleeding owing to perforation of a major blood vessel can be avoidable if operator is experienced and has thorough knowledge of the anatomy and the characteristics of the disease.
The possibility of bronchomalacia after thermal injury to the tracheo-bronchial wall has been reported.6,16 We examined the tissue of surgical specimen. There were 3 cases that underwent radical resection after the treatment of endobronchial electrosurgery. Pathologic examination of the surgical specimen showed degenerative change and fibrosis of tracheal wall in 1 patient who had adenoid-cystic carcinoma of the trachea. Resection of tracheal tumor in the first case required several maneuvers of electrical current at 30 W owing to wide base polypoid elevation. Total application time was more than 70 s, and the duration of application was 10 to 17 s. The other 2 specimens did not show any thermal changes. In these cases, electrical current was applied within 5 s. These pathologic findings showed us that the prolonged application of electrical current caused the thermal change on the tracheal wall.
Rigid bronchoscopy usually requires general anesthesia and is considered more invasive than flexible endobronchial electrosurgery, albeit interventions are easier with the former. In our series, we used local anesthesia with conscious sedation and there was no complaint of unbearable pain or difficulty in breathing. Ample tissue could be resected, as with rigid bronchoscopy. Bronchoscopic electrosurgery using a snare wire yielded large tissue specimens and reduced the tumor size rapidly.
Recovery of resected specimens was sometimes difficult, because biopsy forceps developed for flexible bronchoscopes were designed to handle small specimens. Large specimens difficult to recover with conventional forceps can be harvested by foreign body forceps, or the patient can cough up the resected tumor on bronchoscopist's instructions. Improved devices that can retrieve large specimens are therefore required.
After the analysis of this study, each facility has set up its own standard operational procedures according to the results of this study. In Keio University, we followed the recommendation of this study and have performed 22 more procedures in 14 cases that presented with tracheo-bronchial diseases. In these 14 cases, we have achieved satisfactory results without any complications. We have not encountered any cases that showed massive hemorrhage, airway burn, mediastinitis, or air embolism.
We conclude that endobronchial electrosurgery is a safe and reliable procedure when used according to strict guidelines. This procedure can be applied from the larynx to subsegmental bronchi. The most promising indications for endobronchial electrosurgery are granulomatous polypoid lesions and polypoid malignancy causing stenosis or obstruction of the tracheobronchial tree. When used for biopsy, effective hemostasis can be achieved with minimal thermal effects on tissue specimens. Endobronchial electrosurgery is not suitable for lesions with oozing bleeding or polypoid lesions with calcified components.
The authors are indebted to Prof J. Patrick Barron of the International Medical Communication Center of Tokyo Medical University for his review of this manuscript.
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