I Application of bronchoscopy in the diagnosis of respiratory diseases
1 Diagnosis of common lung diseases by bronchoscopy
1.1 Diagnosis of pulmonary atelectasis and lung shadow etiology
Pulmonary atelectasis is frequently encountered in clinical work. The cause of pulmonary atelectasis can be caused by compression of extrabronchial lesions or by endobronchial obstruction, such as tumor, abscess, tuberculosis, inflammatory reaction, mucus plug, blood clot, foreign body, etc. In recent years, it has been found that the causes of pulmonary atelectasis are significantly increased by lung cancer, followed by inflammatory reaction, and thirdly by tuberculosis. In the past, chest X-ray examination was a more important means of diagnosis of lung diseases, but the diagnosis of etiology was often unclear, especially the cause of pulmonary atelectasis. Observation therapy or open-chest exploration may then delay the diagnosis or bring unnecessary harm to the patient. The majority of causes of pulmonary atelectasis can be determined by observing the lung lobes, segments, and other large airway openings through bronchoscopy. Biopsies and brush examinations of lesions are feasible to obtain pathologic and cytologic diagnoses of intrapulmonary lesions. For example, lung cancer is the most common cause of lung atelectasis, and bronchoscopy is an important and indispensable test for diagnosing lung cancer, especially central lung cancer, which can occur in the main bronchus, and early coughing, hemoptysis and wheezing can occur. Bronchoscopy can usually detect lesions, and if the tumor can be seen, it can directly understand the location, mode and form of tumor growth in the bronchus. Yu Cuixiang, Department of Respiratory Medicine, Shandong Qianfo Mountain Hospital, Shandong Province, China
1.2 Diagnosis of lung infection pathogenesis
In the case of bronchial and pulmonary infections, the sputum coughed up does not necessarily reflect the true situation of bacteria in the lower respiratory tract infection due to contamination by microorganisms in the upper airway. Bronchoscopy is a feasible and safe method of collecting relatively uncontaminated specimens. Specimens obtained after protected specimen brushing (a sterilized double-catheter brush device with a sheath is inserted into the infected area to brush specimens or pus for culture) or protected bronchoalveolar lavage (BALF) for pathogenic examination increase the positivity and specificity, guide the selection of antibiotics, and improve the therapeutic effect; especially in patients with unknown infection etiology and with immune compromise. In principle, bronchoscopy should be performed as early as possible to obtain specimens to avoid further deterioration of the disease.
1.3 Unexplained cough and wheezing
Cough is usually caused by smoking and diseases such as bronchitis, tuberculosis, endobronchial tuberculosis, pneumonia, foreign bodies, and lung tumors. If unexplained cough aggravation and cough that is suboptimal to treatment occur, bronchoscopy is appropriate to clarify the etiology. In general, chronic bronchitis and bronchial asthma can occur with wheezing. If the patient has no similar medical history and the wheezing gradually worsens, such cases mostly suggest local stenosis of the trachea and large bronchi, and the cause may be tracheal or bronchial tumor, tuberculosis, foreign body, inflammation, spasm, etc. Bronchoscopy should be performed as soon as possible to confirm the diagnosis.
1.4 Diagnosis of unexplained hemoptysis
Hemoptysis is a common symptom of respiratory diseases. Common causes include bronchiectasis, lung cancer, endobronchial tuberculosis, pulmonary tuberculosis, bronchiectasis, lung abscess, granuloma, trauma, and abnormal pulmonary vasculature, etc. Bronchoscopy can be performed to identify the cause. In general, bronchoscopy should be performed in all patients with hemoptysis, unless antacid bacilli or tumor cells are found in the sputum. The purpose of the examination is to identify the cause of the bleeding, especially to rule out the presence of a tumor, and also to identify the site of a later unpredictable hemorrhage. Microscopy is most likely to be performed during active bleeding or within 48 hours, and should also be performed even after 48 hours. The cause of hemoptysis is usually clear in the vast majority of patients, but in a few cases the cause of hemoptysis can never be determined. Tracheoscopy is generally not indicated for large hemoptysis of 300-500 ml or more per bleed.
1.5 Diagnosis of diffuse lung disease that is difficult to diagnose
Although diffuse shadows in both lungs can be diagnosed by clinical symptoms, signs, imaging and laboratory data, there are still diffuse lung lesions that are difficult to diagnose, and bronchoalveolar lavage and transbronchial lung biopsy (TBLB) are performed via bronchoscopy to clarify the cause of the disease. Bronchoalveolar lavage fluid can be used for cytologic classification, lymphocyte subpopulation classification examination and chemical composition determination, and lavage fluid can also be used for pathogenic examination and cytopathologic examination for etiologic diagnosis of peripheral lung lesions. Bronchoscopic lung biopsy of diffuse lung disease can clarify the etiology and play a pivotal role in the diagnosis and treatment of the disease, but the small lung tissue specimens obtained by this method do not always allow for an accurate diagnosis and require multiple multi-site biopsies.
1.6 New advances in bronchoscopy in disease diagnosis
Transbronchial needle aspiration (TBNA): Transbronchial needle aspiration is a new technique in which a specially designed needle with a bendable catheter is applied through the bronchoscope to penetrate the trachea or bronchial wall to obtain extraluminal lesions or lymph node tissue for cytopathological examination, and plays an important role in the early diagnosis and clinical staging of lung cancer. It plays an important role in early diagnosis and clinical staging of lung cancer. TBNA can also be used for drainage of adjacent paratracheal cysts.
Endobronchial ultrasound (EBUS): EBUS is based on the use of ultrasound equipment to visualize the airway wall, peri-mediastinal and lung structures within the airway. It is mainly used to observe the size of lesions, tumor invasion, identification of vascular and non-vascular structures, and to guide TBNA to make endobronchial operations easier, such as correct assessment of tumor size for bronchoscopic photomechanics and radiotherapy, and further interventions for airway reconstruction.
Autofluorescence bronchoscopy (AFB): AFB is a new type of bronchoscope developed using cellular autofluorescence and computerized image analysis technology, which can significantly improve the sensitivity of bronchoscopy for early diagnosis of lung cancer and precancerous lesions. The working principle is that under blue laser irradiation, normal tissue areas appear green, while atypical hyperplasia and carcinoma in situ appear brown or red-brown. AFB is recommended for patients with one of the following conditions: ① patients with suspected lung cancer, including patients with suspicious cancer cells found in sputum but normal white light bronchoscopy and fiberoptic bronchoscopy and imaging, or patients with abnormal imaging but no pathological confirmation, etc.; ② asymptomatic long-term smokers (1 pack/day for more than 25 years); ③ patients with diagnosed lung cancer; ④ stage I non-small cell lung cancer reviewed after surgical resection; ⑤ other tumors of the head and neck. ⑤ other tumors of the head and neck. In conclusion, the fluorescence technique utilizes the difference in self-fluorescence of normal tissue, precancerous lesions, and tumors to provide a new method of detecting early tumors, which helps in the early diagnosis of lung precancerous lesions and carcinoma in situ.
Virtual bronchoscopy (VB ): Instead of inserting the bronchoscope into the airway for clinical examination, the data from chest CT and computer software are used to compose bronchoscope-like images. Using 2D imaging to reconstruct the tracheal and bronchial anatomy, the relationship between the airway and other tissues in the chest can be better understood. Advantages:The anatomical structures and pathological changes within the bronchi can be observed without the need for bronchoscopy. Disadvantages:It is not possible to identify benign or malignant tissues, and routine bronchoscopy is still required to obtain tissue specimens for pathological diagnosis. Currently, VB technology is also widely used in clinical teaching and has greatly improved the bronchoscopic skills of interns and junior physicians.
Application of bronchoscopy in the treatment of respiratory diseases
2.1 Removal of foreign bodies and abnormal secretions from the respiratory tract
There are many kinds of inhalation foreign bodies, such as metal, plastic, animal and plant, and most of the inhalation foreign bodies occur in children. Abnormal endotracheal secretions including sputum, pus, blood clots, etc., are often associated with impaired consciousness and inhibition of the cough reflex and airway purification function in critically ill patients, who are particularly prone to airway secretion retention leading to bronchial obstruction, ventilation impairment and respiratory failure; blind suction often fails to relieve the obstruction, and the success rate is high with direct bronchoscopic suction. Bronchoscopic treatment of exhaustion coughing sputum weakness, serious lung infection, sputum embolism pulmonary dysplasia, etc. can be aspirated through bronchoscopy under direct vision sputum or pus embolism; also through bronchoalveolar lavage to remove intrapulmonary secretions, anti-infective drugs can be injected into the side of the lesion to improve the local drug concentration; alveolar protein deposition disease can be treated by alternate lavage of both lungs through bronchoscopy.
2.2 Treatment of tracheal and lung tumors
For endobronchial tumors that block the main airway and cannot be surgically removed, a palliative treatment can sometimes be given through bronchoscopy instead of radiation therapy. Various methods performed through bronchoscopy include implantation of tracheobronchial stents, cryotherapy, electrocautery, laser therapy, placement of radioactive particles, and local application of chemotherapeutic drugs and biological agents, and implantation of particles directly into lung cancer tissues in or outside the narrow tracheal walls through bronchoscopy for brachytherapy. Brachytherapy: Some patients with malignant tumors have already received high doses of external radiation therapy and cannot receive radiotherapy anymore. A brachytherapy catheter with radiation source is placed into the obstructed airway, which can continuously emit low-energy radiation to kill tumor cells continuously and uninterruptedly, thus achieving a therapeutic effect that is difficult to achieve with external radiation. Laser bronchoscopy is suitable for obstructive lesions in the airway, including benign and malignant diseases, and can also be used to prepare for stent placement.
2.3 Transnasal tracheal intubation, assisted placement of tracheo-bronchial stents
Bronchoscopy is used for diseases requiring endotracheal intubation: if intubation is difficult, especially when neck extension is limited, an endotracheal tube can be slipped over the bronchoscope tube diameter to act as a guide to insert the trachea and deliver the endotracheal tube to the proper position. If there is doubt about the position of the endotracheal tube, bronchoscopy can be used to verify it. After removal of the tracheal tube, bronchoscopy can be used to examine damage to the trachea, vocal cords, and vocal cords caused by the intubation.
Central tracheal stenosis caused by advanced lung cancer often results in significant respiratory distress and poor quality of life. Stent placement through bronchoscopy can dilate the narrowed trachea, rapidly improve the ventilation function, enhance the patient’s quality of life, and create conditions for further treatment. Currently, the commonly used airway stent is a nickel-titanium memory alloy stent, which has the advantages of super elasticity, wear resistance, good histocompatibility and memory effect. Endotracheal placement of nickel-titanium memory alloy stent through bronchoscopy to relieve local airway stenosis can immediately relieve the symptoms of airway obstruction in 90% of patients.
2.4 Advances in bronchoscopic treatment techniques
Laser bronchoscopy: The local action of the laser causes the tumor tissue to cauterize and decompose, and its penetration is strong enough to relieve the narrowing or obstruction caused by the tumor tissue. In general, rigid bronchoscopy is more convenient for laser treatment than fiberoptic bronchoscopy because it is more attractive and easier to grasp post-cut debris, while allowing compression for hemostasis and to some extent airway dilation. During laser treatment, the operator takes care to wear protective eye wear and to prevent intra-airway burning, the oxygen concentration in the airway is as low as possible ( ≤40% ). The main complications are severe hemorrhage, pneumothorax, mediastinal emphysema, esophageal tracheal fistula, small airway obstruction, as well as causing deep and superficial vascular laser coagulation, tissue necrosis, airway wall penetration, etc. Basic indications for laser treatment: ① benign or malignant airway lesions, such as malignant tumors, benign tumors and inflammatory granulomas in the bronchus, accompanied by severe dyspnea and uncontrollable cough and wheezing; ② inability to get off the ventilator due to airway obstruction; ③ obstructive pneumonia; ④ symptomatic or unresponsive atelectasis; ⑤ obstruction of more than 50% of the main airway on one side; ⑥ bronchopleural fistula for which conventional treatment is ineffective. Regardless of the condition, laser therapy is contraindicated as long as the lesion is extra-airway. Other contraindications to laser treatment include: ① lesions invading the peri-vascular area (e.g., pulmonary artery) with the possibility of fistula formation, ② lesions invading the esophagus with the possibility of fistula formation, ③ invading the mediastinum with the possibility of fistula formation, ④ patients undergoing elective surgery, ⑤ those with a short expected survival period, and ⑥ those with impaired coagulation mechanisms.
Bronchoscopic electrosurgery and argon plasmacoa gulation (APC): both bronchoscopic electrosurgery and APC refer to the rapid coagulation or evaporation of tissues by generating heat through high-frequency electric current, the difference between the two is that APC mediates the electric current through argon plasma without direct contact with tissues, so APC can only penetrate a few millimeters of tissues and is more suitable for superficial, extensive lesions of the airway. When the gas is released from the catheter tip, the arched heat is released through the current, causing thermal damage and intense drying to shrink the lesioned tissue. Because the arch ring can be moved back and forth or even bent, APC is also suitable for manipulation of lesions in some hard-to-reach areas. Bronchoscopic electrosurgery requires direct contact with the tissue, and different probes and loops are selected depending on the lesion site. The indications, precautions, and comorbidities are the same as for other thermal treatments, with airway oxygen concentrations ≤ 40% and complications such as bleeding, airway perforation, and stenosis. Patients can be in remission for several weeks to months.
Cryotherapy: Transbronchoscopic cryotherapy is the repeated application of rapid freezing and slow thawing, resulting in the death of malignant cells by crystallization of water outside the cells, crumbling of cells, and rupture of cell membranes. Nitrogen oxide or liquid nitrogen are commonly used substances that can produce a low temperature of -80 °C. Cryoprobes can be used for both rigid bronchoscopy and fiberoptic bronchoscopy. Different tissues have different sensitivities to freezing, and tumor tissue within the lung is more sensitive to freezing than normal lung tissue. Repeated freezing is needed at the same site of the lesion, and the efficacy appears after a few days, so repeated bronchoscopy is needed.
Indications:Benign and malignant lesions in the airways, visible, smaller polypoid lesions in the distal bronchi are most suitable for this type of treatment. Certain airway foreign bodies are also suitable for cryotherapy. Lesions with a high degree of malignancy are not suitable for this procedure because they do not immediately destroy the lesion. Some lesions, such as fibrous scar lesions, are not effective with cryotherapy. Advantages: simple and inexpensive equipment, easier to handle than laser therapy.
Photodynamic therapy (photod ynamictherapy): Photodynamic therapy refers to the intravenous injection of a certain dose of photosensitizer, after a certain time interval (usually 1~2d, often ≤7d) to do bronchoscopy, giving a certain dose and wavelength of light irradiation to the lesion area, thus generating reactive oxygen species and causing oxidation of adjacent tumor cells. The effect of this treatment cannot be observed immediately and is usually observed within 48h. Bronchial bronchoscopy is often repeated 1 to 2d after treatment, and the treatment can be repeated several times for residual lesions if necessary. The indications for photodynamic therapy are mainly for the relief treatment of superficial airway tumors that are not suitable for surgery or radiation therapy and airway obstruction caused by malignant tumors. It is suitable for various tumors that have already undergone surgery, radiotherapy and chemotherapy, and the efficacy is independent of the cell type. The most common of the complications, other than those caused by the tracheoscopic procedure itself, is skin photosensitivity, which can last up to 8 weeks after intravenous administration of photosensitizing agents, and light exposure should be avoided during this phase. Local complications include airway edema, necrosis, tracheal vascular fistula due to tumor breakdown, tracheoesophageal fistula, and occasionally fatal hemorrhage has been reported.