When laser light irradiates biological tissues, four biological effects of light absorption, reflection, conduction and diffusion can occur. When the laser irradiates the living tissue, part of it is absorbed by the tissue, and the light energy can be converted into heat energy to produce a series of tissue changes, such as cell edema and death, protein coagulation, tissue water boiling, and combustion of dehydrated tissues, etc., and the other part of it can be transmitted and diffused through the tissue to produce the after-effects. Transbronchoscopic laser therapy, mainly using the thermal effect of laser, so that the irradiated tissue appears coagulation, vaporization or carbonization and achieve the purpose of eliminating lesions.
1. Laser treatment of airway lesions of the indications
Transbronchoscopic visible obstruction caused by new organisms in the airway, with the fiber-optic guide can be accurately aligned to facilitate the operation of the site can be applied to laser therapy. Currently, laser therapy is rarely used for airway diseases.
1) primary and metastatic malignant tumors in trachea and bronchus: including primary bronchopulmonary cancer, sarcoma, carcinosarcoma, teratoma, lymphoma, plasma cell tumor, carcinoid tumor, adenoid cystic carcinoma and so on. It is generally used for malignant tumors that have lost the chance of surgery or advanced stage of tumors. For those who have difficulty in ventilation due to the proliferation of diseased tissues in the airway obstructing the large airway, laser can ablate and recirculate the obstructed tissues, improve ventilation, and alleviate or cure the respiratory difficulty.
2) trachea, bronchial benign tumors: including misshapen tumors, papillomas, polyps, chondrosarcomas, lipomas, fibrous smooth muscle tumors, fibromas, endometriosis, bronchial stones, scleroderma, hemangiomas, neurinoma and so on. Benign tumors are generally more limited, easy to remove with laser, rarely recur, so the laser is extremely effective in the treatment of benign tumors, benign tumors in certain parts of the body can replace surgical treatment.
3) Tracheal and bronchial granuloma: mainly includes foreign body granuloma, tuberculous granuloma and inflammatory granuloma caused by surgical suture and tracheotomy metal cannula. Laser is very effective in the treatment of foreign body granulomas, but less effective in the treatment of tuberculous and inflammatory granulomas, but at least it can make the airway reopen and improve pulmonary ventilation. Treatment of tuberculous granulomas is best done after the lesion has been stabilized by anti-TB therapy.
4) Organic tracheal and bronchial stenosis: scarring stenosis mainly due to tracheotomy or tracheal intubation, diphtheria, trauma, endobronchial tuberculosis, etc., especially medical tracheotomy or intubation. Laser treatment is more effective for undamaged cartilaginous rings and ineffective for bottleneck-like and external pressure stenosis.
5) Others: such as tracheo-bronchial endotracheal hemorrhage, tracheo-bronchial fistula, tracheo-bronchial endotracheal membrane atypical hyperplasia. Due to the obvious protein coagulation and vascular closure effect of laser, appropriate reduction of laser power can be used for hemostatic treatment in the airway.
2. Contraindications and precautions for laser treatment of intra-airway lesions
The contraindications for laser treatment are similar to those for conventional bronchoscopy, but because the operation is often performed under general anesthesia, the contraindications are also consistent with those for general anesthesia. However, in terms of endoscopic laser technology, the main contraindications are:
1) Extravasive stenosis of the trachea-bronchial lumen is mainly caused by mediastinal tumors, lymphadenopathy, and lung lobe atrophy, and ablation therapy will cause perforation of the trachea-bronchial wall, which is an absolute contraindication to ablation therapy.
2) The effect of ablation therapy is poorer in long-distance funnel-shaped stenosis of the airway with submucosal infiltration.
3) Ablative therapy is also tricky in complete airway occlusion, and the path of the obstruction and the distal end of the obstruction must be evaluated preoperatively, otherwise wall perforation is likely to occur. In cases of incomplete airway occlusion, the function of the lung tissue distal to the obstruction must be evaluated before ablation therapy, and if the distal lung tissue loses gas exchange capacity, ablation therapy is no longer necessary.
4) When the tumor erodes the posterior wall of the trachea and affects the esophagus, the chances of perforation and sinus tract formation are high with ablation therapy. Lung cancer patients receiving long-term extensive radiotherapy are also prone to perforation due to the tendency of twisting and softening of the tracheal wall during radiotherapy, and ablation therapy is also prone to perforation at this time.
5) Special care should be taken in the ablation treatment of upper lobe lesions, as the location is close to large blood vessels, which may lead to hemorrhage if not careful.
6) Small cell lung cancer and lymphoma are diffuse lesions, often involving the airways, chemotherapy can achieve good results, the choice of ablation treatment should be well-timed.
7) Abnormal coagulation function, electrolyte disorders, hypotension and serious infection should be considered as contraindications.
3. Specific steps and methods of operation
Transbendable bronchoscopy treatment can be carried out under local anesthesia or general anesthesia, the use of general anesthesia when the preoperative preparation is the same as the general general anesthesia surgery, the use of local anesthesia and the preoperative preparation is the same as the ordinary bronchoscopy. First preheat the laser treatment instrument, laser power 100 watts, wavelength 1064 nanometers. Conventional anesthesia, anesthesia as superficial as possible, as far as possible on the patient's respiratory inhibition to minimize the degree, while the application of 2% lidocaine surface anesthesia of the airway to reduce the irritation response. An endotracheal tube was inserted, and bronchoscopic treatment was applied through the tracheal cannula. The bronchoscope was inserted to the lesion, and a light-guided fiber was inserted through the bronchoscopic biopsy hole and extended out at least 1 cm from the distal end of the bronchoscope, and visible red light was applied to localize the ablation target, which was aligned to and 4-10 mm away from the target of the ablation, and irradiated with the Nd:YAG laser. The footswitch was controlled by the operator, and the power used was generally 20-40 watts, with each irradiation (pulse duration) of 0.5-1 second at intervals of 0.1-0.5 seconds. The energy used depends on the size of the lesion, and it is safer to irradiate the larger lesions in stages, with an interval of 1-2 weeks between each treatment. Argon Plasma Coagulation (Argon Plasma Coagulation, APC) has been widely used in the treatment of respiratory diseases, and has become an important technical means of treatment of respiratory diseases.
Argon is an inert gas, under the action of high-frequency current argon current ionization occurs, the ionized argon plasma beam has conductivity, can direct the current from the high-frequency output electrode to the tissue, and focus on a point of contact with it. Argon plasma beam has a tendency to movement, the direction of its movement is determined by the shortest distance from the nozzle to the organization, in order to minimize the movement impedance of the argon plasma beam.
Transbronchoscopic argon knife treatment is mainly applicable to localized bleeding in the trachea and bronchus within the visual range, foci of growth elevation in the lumen of the respiratory tract, luminal narrowing, and foreign bodies, such as benign stenosis of the respiratory tract (anastomotic scarring stenosis), carcinomatous obstruction foci in the main airway and the left and right tracheal openings, granulomatous proliferative foci of the airways, foreign bodies with fixed stitches in the respiratory tract, foreign bodies with respiratory tract food, Extensive exfoliative lesions of the respiratory mucosa (mycobacterial infection of the respiratory mucosa after bone marrow transplantation). Those who are not suitable for bronchoscopy, non-respiratory hemorrhage (e.g., branchial dilatation, tumor invasion of thoracic macrovascular hemorrhage) are absolute contraindications. High-frequency electricity is used for endoscopic treatment by means of electrocoagulation and electrodesiccation. High-frequency electrical energy generates heat energy, which acts on the tissues, causing coagulation, necrosis, carbonization and vaporization, and at the same time occludes the blood vessels. High frequency electrotherapy devices generally have three treatment modes: electro-cutting, electro-coagulation and hybrid cutting.
High-frequency electrotherapy is suitable for the palliative treatment of malignant tumors in the trachea and bronchial lumen that have lost the chance of surgery; the radical treatment of all kinds of benign tumors in the trachea and bronchial lumen; and the resection of all kinds of inflammation, surgery, traumatic injury, and granulomas of foreign bodies. Patients with cardiac pacemakers should not be treated with high-frequency electrotherapy, so as not to malfunction the pacemaker or cause myocardial burns and other injuries. Cryotherapy was mainly used in the treatment of various skin diseases in the early stage, and has since been widely used in the treatment of various tumors with the development of various cryogenic instruments. The damage caused by cryopreservation can occur at the molecular, cellular, tissue and organ levels. The rate of local cooling and lysis and the lowest temperature that can be reached determine whether the cells can survive or not. The sensitivity of tissues to cryopreservation is usually related to their water content, with tissues containing more water being relatively sensitive to cryopreservation and tissues containing less water being more tolerant to cryopreservation. Generally tumor tissues are more sensitive to freezing than normal cells.
Cryotherapy is suitable for the palliative treatment of malignant tumors in the lumen of the trachea and bronchus; the radical treatment of benign tumors in the trachea and bronchus; the treatment of restenosis at both ends and in the lumen after stent implantation; and the removal of foreign bodies or blood clots in the trachea and bronchus.
After cryotherapy, complete intravascular thrombosis occurs 6-12 h after treatment, and in the following days, cells will undergo denaturation and necrosis, and non-hemorrhagic necrosis of tissues occurs 8-15 days after treatment. Because of the delayed effect of cryotherapy, it is not indicated for relieving acute airway obstruction. Transbronchoscopic (high-pressure) balloon dilatation is used primarily for the treatment of central airway stenosis. The principle is that the balloon is placed in the narrowed airway and the balloon is dilated by pressurizing the balloon with a high-pressure gun pump, which creates multiple small longitudinal fissures around the entire circumference of the narrowed area of the trachea, and the fissures are filled with fibrous tissues, thus achieving the dilation of the narrowed area.
1. Indications for balloon dilatation
Balloon dilatation has no therapeutic effect on the cause of the disease, and is mainly used for main airway stenosis caused by benign scarring lesions, and only as an adjunctive treatment for airway stenosis caused by malignant diseases.
1) Tracheal and bronchial tuberculous stenosis, mainly bronchial stenosis caused by scar contraction after bronchial tuberculosis is cured.
2) Medical airway stenosis: after tracheotomy, after prolonged tracheal intubation, after radiation therapy, and anastomotic stenosis after lung surgery (e.g., after lung transplantation, sleeve resection, and trachelectomy).
3) Inflammatory diseases involving the airways, such as tuberculosis and Wegner's granulomatosis.
4) Post-traumatic airway stenosis.
5) Congenital airway stenosis.
6) Malignant airway stenosis: exopressor or combined exopressor airway stenosis, adjunctive dilation of the airway to facilitate airway stent extension, and assistance in placement of therapeutic airway catheters.
2. Contraindications to balloon dilatation
1) Loss of lung function at the distal end of the stenosis, although the airway is open, but the lung function is unlikely to be any better.
2) Severe coagulopathy.
3) severe cardiopulmonary insufficiency, the patient can not tolerate, lost the opportunity for treatment; but if the main tracheal stenosis caused by cardiopulmonary insufficiency, should be actively treated to strive for an early resolution of the cause of the disease, to achieve the purpose of treatment.
4) After surgical sleeve anastomosis, the tension of the trachea has been inconsistent, and it is easy to cause laceration of the anastomosis during dilatation treatment, so dilatation treatment needs to be careful.
5) Tracheal tenderness is not an indication for balloon dilatation therapy, the destruction of bronchial cartilage leads to the disappearance of the supporting effect of the tracheal wall, the lumen can be expanded during balloon dilatation therapy, but the lumen will be retracted as soon as the balloon is relaxed.
3, the timing of treatment and precautions
Tuberculosis-induced bronchial stenosis, preoperative anti-tuberculosis treatment should be adequate. It is recommended to adhere to regular anti-tuberculosis treatment for 9 months after surgery; the bronchus has no obvious active tuberculosis lesions at the time of treatment; do not use heat therapy or stenting in the treatment of bronchial tuberculosis; after dilatation, obvious infection or active tuberculosis foci should be found to immediately stop dilatation treatment, change to anti-inflammatory or anti-tuberculosis treatment, and then dilatation treatment after the absorption of the inflammation; for the obvious contraction of bronchial tubes during anti-tuberculosis treatment should be closely observed. Be sure to keep the lumen of the tube is not closed, for the opportunity to expand the treatment.
4, the operation of the specific steps and precautions
1) anesthesia: the main tracheal lesions, stenosis, serious expansion of patients with a long time to choose general anesthesia; lesions located in the main bronchus, but the contralateral side of the lung function is poor, local anesthesia may not be able to complete the expansion of the operation, general anesthesia is recommended.
2) choose the appropriate balloon catheter: know the diameter and length of the normal trachea and bronchus: trachea diameter of 16-20mm, length of 10-325px; the right main bronchus diameter of 12-15mm, length of 1-50px; the right middle section of the bronchus diameter of 12mm, length of 75px; the left main bronchus diameter of 10-14mm, length of 125px. at present. The balloon manufactured by Boston Scientific is commonly used, and the appropriate balloon catheter is selected according to the inner diameter of the working orifice of the therapeutic bronchoscope as well as the diameter and length of the balloon.
3) Placement of the catheter and dilatation: Currently, the balloon catheter is placed through the working channel under the guidance of the bronchoscope, and the dilatation position is determined under direct vision, and water is injected into the balloon with a pressure gun pump, and the pressure can be chosen from 3-8 atmospheres in order to achieve different dilatation diameters, and the pressure needs to be increased from low to high. Each dilatation operation is about 30-60 seconds, observe the effect, if it is not effective, we can use cryotherapy to treat the lesion and then dilatation, if it is still not effective, can be given to high-frequency electroacupuncture to cut off the scar and then dilatation. Be careful not to cut the tracheal membrane. Depending on the degree of dilatation, each operation can be repeated 1-10 times. If there is no therapeutic tracheoscopy, the combination of fluoroscopy and tracheoscopy can be used. The guidewire and balloon catheter are first placed under fluoroscopy to determine the location of the corresponding stenosis, and the bronchoscope is inserted to observe the balloon catheter and the stenosis, which facilitates the operator's observation of the process of direct-vision balloon dilatation.
4) Precautions: for the dilatation of upper tracheal stenosis, pay attention to the protection of the vocal cords; gradually increase the pressure during the operation, so as not to cause tracheal wall lacerations; the balloon must be completely into the airway, to avoid damage to the bronchoscope; more than the dilatation of the bronchial stenosis, pay attention to the importance of not inserting the deepest, so as to avoid damaging the normal airway at the distal end.
5. Common complications
1) Bleeding from the tube wall: Bleeding is the most common complication. However, in general, bleeding is not much, no need to deal with it; when bleeding is much, it can be diluted in thrombin or epinephrine (1:10,000 for local use), and the clear bleeding point can be given to APC local electrocoagulation treatment.
2) Bronchial rupture: after the treatment, patients appear mediastinal or neck subcutaneous emphysema, which is caused by tracheal rupture during dilatation. Generally after resting most of them can be self-healing. At this time, we should pay attention to let the patient minimize coughing and give infection prevention treatment.
3) Recurrence of stenosis: It is necessary to distinguish between recurrence due to uncontrolled tuberculosis infection or recurrence of stenosis due to proliferation and contracture of scar caused by the patient's keloid body. In the first case, active anti-tuberculosis treatment. In the second case, repeated dilatation and freezing are needed, and radiation therapy can be used in some patients to inhibit scar proliferation. Even after the above treatments, some patients still have stenosis that cannot be controlled, and other treatments are needed. Airway stents can be divided into two categories, silicone tubular stents and metal mesh stents (coated or uncoated), according to the materials used to make them, and each has its own advantages and disadvantages.
Compared with the metal mesh stent, silicone tubular stent is cheaper; the position of the stent is easier to be adjusted and removed during the stent placement process, but the stent placement needs to be carried out under general anesthesia using rigid bronchoscopy, which affects the mucus cilia clearing function, and is more likely to occur in secretion obstruction lumen, and prone to stent dislocation, especially for the short conical airway stenosis, and the adherence to the wall is worse, and should not be used for the irregular or surface airway stents. It is not suitable for stenosis with irregular airway or uneven surface. Currently, silicone stents are not available in China.
Compared with the silicone tubular stent, the metal mesh stent is easier to place, and most patients can be placed under local anesthesia with a bendable bronchoscope; the metal mesh stent has good elasticity, so the incidence of dislocation after placement is relatively low; the stent is thinner, with a high inner/outer diameter ratio, and it can preserve the mucus-clearing function of the airway to a certain extent. The disadvantage of metal mesh stents is that (uncoated) metal mesh stents have a higher rate of restenosis in the stent lumen due to tumor or granulation tissue growth through the mesh. Because metal mesh stents are not easily removed after implantation, they should be used with caution in benign airway stenosis, especially in patients with acute inflammation at the site of the lesion, and the use of removable metal stents (e.g., Lee's stent) is currently advocated.
The indications for tracheal and bronchial stenting mainly include three aspects: ①The central airway (including the trachea and bronchial tubes above the segment) organic stenosis of the lumen reconstruction. ② Support for cartilage weakness in tracheal and bronchial chondromalacia. ③ Sealing of tracheal and bronchial fistula or fissure.
The etiology of organic stenosis of the central airway includes both malignant tumors and benign lesions. For airway stenosis caused by malignant tumors, if the time for surgical treatment has been lost, in most cases it is necessary to remove the luminal tumor tissue by laser, argon knife, high-frequency electrocautery or cryotherapy under bronchoscopy. If at this time the patient has airway obstruction and dyspnea due to extensive infiltration of the tube wall tumor or compression by extra-luminal tumors and metastatic lymph nodes, temporary stent placement at the site of airway obstruction can be performed. Currently, malignant airway stenosis is considered to be an indication for endo-airway stent placement. The etiology of benign airway stenosis is relatively complex. In China, tracheal and bronchial tuberculosis and mucosal injury caused by tracheal intubation or incision of high cannula balloon pressure are the most common causes. For benign airway stenosis, stenting should be done with caution, and the principle of stenting should be that after laser, high-frequency electrocautery or freezing and balloon dilatation, the efficacy of which is difficult to be maintained, only then should endotracheal stenting be considered, and at the same time, it is advocated to apply the removable stent.
Destruction and defects of tracheal and bronchial cartilage caused by bronchial tuberculosis, recurrent polychondritis, and other inflammatory diseases or mechanical compression often result in abnormal movement of the airway wall at the cartilage defects. Stent placement is sometimes the only option available for such patients.
Fistulas between the esophagus and the trachea or bronchus can be congenital, but the vast majority seen clinically are the result of malignant tumors. Clinical symptoms of tracheoesophageal fistula mainly include choking, dyspnea and aspiration pneumonia when drinking and eating. Tracheoesophageal fistula caused by infiltration of esophageal tumor into the airway, esophageal stenting can improve the quality of life of patients, but generally not completely effective in closing the fistula, esophageal and airway double with membrane stenting can be achieved a more satisfactory clinical results.
Bronchial stump and bronchial anastomotic fistula or fissure are common complications of lobectomy and bronchial sleeve resection for central lung cancer. In addition to the previous bronchoscopic gelatin sponge, cellulose, and medical adhesive local closure, the placement of a stent with a membrane or the filling of gelatin sponge followed by the fixation of an ordinary metal stent is also a common and effective method of tracheal and bronchial fistula or fissure sealing in recent years. Generally, the establishment of artificial airway is completed by anesthesiologists, but tracheal intubation is often difficult for some patients, such as: cervical spondylitis, myasthenia gravis, acromegaly and severe head trauma patients. At this point, the application of bronchoscopy to guide intubation is the only option. In addition, due to the intuitive visualization of bronchoscopy, the damage caused by routine blind intubation can be avoided, especially for patients who may have upper airway abnormalities that make intubation difficult. When split-lung mechanical ventilation is required, double-lumen tube tracheal intubation must be performed, guided by bronchoscopy is an excellent method, and for the determination of the position of double-lumen tracheal intubation, bronchoscopy is the most reliable tool.
The bronchoscope is also a very useful tool in changing tracheal intubation. In the ICU ward, often due to the rupture of the airbag, tracheal tube model is too thin need to replace the tracheal tube, or need to change the oral intubation into transnasal intubation, the application of bronchoscopy to assist in the replacement of the tracheal tube, not only can observe the original tracheal tube and the airway, easy to detect abnormalities in a timely manner, and can be re-established in the shortest possible time artificial airway, to reduce the lack of oxygen on the impact of critically ill patients.
Clinically, some patients suddenly experience respiratory distress after extubation, which is partly due to Upper Airway Obstruction (UAO), which mostly occurs under the vocal folds or at the vocal folds. An artificial airway must be reconstructed when UAO occurs, and although reintubation quickly relieves the patient's respiratory distress symptoms, the cause of UAO remains unidentified. In patients with possible UAO, a bronchoscope is inserted at the time of extubation, and the bronchoscope is withdrawn together with the tracheal tube, so that the cause of UAO can be found, and at the same time, the tracheal tube can be reintubated immediately to avoid the effects of UAO on the patient. The management of UAO is then sought according to the situation.The occurrence of UAO is generally associated with patients who have been intubated before and are difficult to intubate and who have undergone repeated attempts at intubation, as well as with prolonged mechanical ventilation. Acute and chronic lung abscesses, pneumonia, and bronchial infectious diseases often result in poor efficacy of systemic medications due to the blood-bronchial barrier, tissue encapsulation, and the physicochemical nature of the pus. Transbronchoscopic drainage and drug administration can increase the local drug concentration. Generally, the bronchoscope is inserted into the directed lung segment, lobar bronchus, first fully attracted sputum, and then a small amount of saline rinse, the rinsing fluid will be suctioned clean, injected with antibiotics containing sensitive, non-irritating respiratory effects, such as: penicillin, butamidokanamycin, cephalosporins dissolved in saline 10ml injected into the lesion as a retention of the therapeutic drug. The total volume of irrigation should not exceed 100 ml. If the condition is critical, the operation time should be limited to 15 minutes, and may not be rinsed.
Chronic obstructive pulmonary disease (COPD) with respiratory failure or other critical patients often due to viscous sputum or blood clots blocking the larger airways, resulting in segmental, lobar or one side of the lung atelectasis, when the patient's condition is often acute exacerbation and can be life-threatening. When the use of stimulation of cough, deep breathing exercises, back patting and postural drainage and other measures are still ineffective, the use of bronchoscopy for suction and lavage can effectively lift the lung atelectasis and thus save the patient's life. Some patients, such as rib fracture, hemothorax, pneumothorax and post-surgical patients, cannot be stimulated to cough by patting the back, etc., and bronchoscopy becomes the only effective tool to relieve pulmonary atelectasis. Generally after bronchoscopic suction and irrigation, most of the lung atelectasis can be lifted.