Medicalthoracoscopy (also known as Pleuroscopy) is an invasive technique used to treat patients with pleural effusions that cannot be diagnosed by non-invasive methods. The ability to observe changes in the pleural cavity under direct vision and to perform biopsies of the pleural wall layers and/or dirty layers makes the application of this technique clinically important for the diagnosis of pulmonary pleural disease.
I. Concept of internal thoracoscopy
(A) History of internal thoracoscopy
In 1910, Jacobaeus, an internist in Stockholm, Sweden, used a thoracoscope under local anesthesia to perform a diagnostic examination of patients with exudative pleurisy, which was the earliest “diagnostic thoracoscopy”. In the early 1960s, with the advancement of anti-tuberculosis drugs, tuberculous pleural adhesions decreased significantly, and some European internists, who were familiar with the application of thoracoscopy, started to use thoracoscopy to treat patients with pneumothorax. In the early 1960s, with the progress of antituberculosis treatment drugs, tuberculous pleural adhesions decreased significantly, and some European internists familiar with the application of thoracoscopy began to use thoracoscopy to diagnose and treat pulmonary pleural diseases, mainly for the diagnosis of tuberculosis and malignant pleural effusion; meanwhile, some American physicians also began to apply this technology in clinical practice.
In the 1990s, due to the development of endoscopic technology and the requirement of minimally invasive operation, “surgical thoracoscopy” emerged, which is mainly the Video-assisted thoracoscopicsurgery (VATS) that we see now. The use of surgical thoracoscopy has led to a greater awareness and use of “medical thoracoscopy” by pulmonologists. According to a 1994 survey of 1,000 pulmonologists in the United States, approximately 5% of U.S. pulmonologists used internal thoracoscopic techniques to treat pulmonary pleural disease. In Europe, thoracoscopic techniques are included in the training programs of pulmonologists. In China, several hospitals have also used plain rigid thoracoscopy or bronchoscopy instead of thoracoscopy for the diagnosis of pulmonary pleural disease in recent years.
In recent years, a new type of combined soft and rigid thoracoscope has emerged, which consists of a bendable front end with a rigid operating rod section that is easier to handle than the traditional rigid thoracoscope. Many physicians have started to use this type of endoscope with a bendable tip (Flexirigidthoracoscopy, or semi-rigidthoracoscopy) in clinical practice.
(B) Differences between medical and surgical thoracoscopy
Thoracoscopy provides clinicians with the opportunity to look directly at lesions in the pleural cavity and possibly diagnose and/or treat the lesions. The main differences between medical and surgical thoracoscopy are the following: 1) medical thoracoscopy is performed by a pulmonologist or respiratory endoscopist in the tracheoscopy room, whereas surgical thoracoscopy is performed by a thoracic surgeon in the operating room; 2) medical thoracoscopy uses a single incision in the chest wall under local anesthesia (or with intravenous sedation) to complete observation of the pleural cavity and biopsy of the lesion, which is easily tolerated by the patient, whereas surgical thoracoscopy requires general Surgical thoracoscopy requires general anesthesia and double-lumen tracheal intubation to ensure the operation on the affected side; 3. Internal thoracoscopy rarely uses disposable supplies and does not require general anesthesia, so the cost is significantly lower than that of surgical thoracoscopy; 4. Internal thoracoscopy is mainly used for diagnosis as well as adhesion release and pleural fixation because of the small field of view and only one observation incision, while surgical thoracoscopy can complete operations such as lesion removal and pleural release of serious adhesions.
Each of medical and surgical thoracoscopy has its own different indications. Here, we mainly introduce the technique of medical thoracoscopy and its clinical application, so that more respiratory physicians can understand and use this technique.
II. Technical operation of medical thoracoscopy
(I) Instruments and equipment
Internal thoracoscopy is a less invasive operation that requires only an incision in the chest wall. The devices used include a chest wall puncture trocar, a thoracoscope or a substitute fiberoptic bronchoscope with its light and image system, biopsy forceps and postoperative chest drainage. The thoracoscope used for examination differs from region to region depending on the conditions, and there are three main types as follows: 1. Ordinary rigid thoracoscope, which is different from surgical thoracoscope in that it is a guide beam, eyepiece and biopsy orifice all set in one metal tube, and when the operator is operating, he can directly use rigid biopsy forceps to biopsy the lesion area. Usually because the working orifice is thicker, so the biopsy forceps are relatively larger, the biopsy tissue is also larger, and the pathology positive rate is higher. Its shortcomings are inflexible operation, not easy to change the direction of multi-angle observation of changes in the thoracic cavity. 2, bronchoscopy instead of thoracoscopy: some authors in China use this method, which can be used in areas without thoracoscopic equipment for the diagnosis of pleural disease. There are certain disadvantages compared with rigid mirror, such as: the positioning of tracheoscope in the thoracic cavity is not easy to control, and the biopsy sampling is small. 3, front-end bendable electronic thoracoscope: this is a new type of equipment appeared in recent years, its rigid rod part has the ease of operation of ordinary rigid thoracoscope, and the front-end bendable part can observe changes in the thoracic cavity in multiple directions, and it uses the same light source monitoring system with electronic tracheoscope, which has good application prospects.
(B) Operation process
1.Selecting the puncture point: The prerequisite for thoracoscopic operation is sufficient pleural cavity space, at least 6-10 cm, which is usually easy to operate in patients with pleural effusion without adhesions. If there is no sufficient pleural space, an artificial pneumothorax under X-ray guidance before or at the time of thoracoscopy is required to create a safe puncture space to avoid damage to the lungs. Hersh et al. reported that transthoracic wall ultrasound selection of the puncture site for trocar placement is both safe and effective without the need for preoperative artificial pneumothorax, while ultrasound saves time, so ultrasound localization of the puncture needle inlet can replace internal medicine Pre-thoracoscopic manual pneumothorax. Usually the patient takes the healthy side lying down, and the incision is chosen in the 4th-8th intercostal space of the chest wall in the axilla of the affected side, commonly 6-7th intercostal space.
2.Local anesthesia: Local anesthesia of 5-20 ml of 2% lidocaine is given at the puncture site. Those with significant pain can be sedated with intramuscular dulcolax or intravenous midazolam and fentanyl, and cardiac, electrical, blood pressure, and oxygen saturation monitoring is performed to keep the patient breathing well on his own.
3. Incision, placement of thoracoscope and observation of pleural cavity: A 9-mm incision is made at the puncture site, the subcutaneous layers are bluntly separated to the pleura, a puncture cannula is placed, and the thoracoscope is sent into the pleural cavity through the cannula to observe the visceral, mural, diaphragmatic pleura and peri-incisional pleura in the order of internal, anterior, superior, posterior, lateral and inferior. Suspicious lesions may be biopsied. When encountering thoracic adhesions, electrocoagulation or electrodesiccation can be used to loosen the adhesion zone, but attention needs to be paid to bleeding. Since internal thoracoscopy is not as convenient and reliable as VATS to stop bleeding, special attention should be paid to separation, rather slow than fast, and the coarser adhesion zone and the longer adhesion zone are prone to small blood vessels, which can be first sprayed locally with norepinephrine, multi-point segmental electrocoagulation and cautious electrodesiccation. In case of malignant pleural effusion or recurrent benign effusion requiring pleural fixation, 3-5g of sterilized dry talcum powder is commonly sprayed evenly into the pleural cavity through an atomization device. For patients with pneumothorax, 2-3g of talcum powder is sufficient, and postoperative closed chest drainage needs to be left in place for negative pressure suction.
4.Postoperative: After the operation is completed, a closed drainage tube is placed into the chest cavity via trocar, and postoperative X-ray chest film is performed to understand the position of the placed tube and changes in the chest cavity.
(C) Indications
Internal thoracoscopy is mainly used for diagnosis, but also for partial intrathoracic treatment. The main indications are: 1) pleural effusion whose etiology cannot be clarified by various non-invasive methods; 2) staging of lung cancer or pleural mesothelioma; 3) talc pleural fixation for patients with malignant effusion or recurrent benign effusion; 4) for stage I and II of spontaneous pneumothorax, local treatment is also an indication for endoscopic thoracoscopy; 5) other indications include the need for biopsy in the diaphragm, mediastinum and pericardium Other indications include the need for biopsy of the diaphragm, mediastinum and pericardium.
(iv) Contraindications
Endoscopic thoracoscopy is a safe procedure. Pleural cavity occlusion is an absolute contraindication to this test, so severe pleural adhesions should not be examined. Relative contraindications include: 1, bleeding disorders, with platelets below 40,000 as the threshold; 2, hypoxemia; 3, severe cardiovascular disease; 4, persistent uncontrollable cough; 5, extreme weakness.
(V) Complications and their prevention
Common complications include cardiac arrhythmias, mild hypertension or hypoxemia, and most of these complications can be completely corrected by oxygenation.
Most bleeding after biopsy can be stopped spontaneously, and for relatively minor persistent bleeding, electrocoagulation can be used to stop the bleeding. The experience of Loddenkemper et al. who performed more than 6000 thoracoscopic cases pointed out that bleeding due to thoracoscopy does not require surgical intervention. The relatively least common but serious complication is bleeding due to vascular injury, which is also the main cause of death and requires urgent open-heart surgery to stop the bleeding. Post-biopsy pneumothorax and bronchopleural fistula are rare, and choosing a safe puncture site and careful biopsy can avoid this complication. The most dangerous complication caused by manual pneumothorax is embolization of air or gas, with an incidence of less than 0.1%. The risk of retensioned pulmonary edema after pleural aspiration is minimal; even if several thousand milliliters of pleural fluid are completely aspirated during thoracoscopy, an equivalent amount of gas will soon enter the chest cavity through the chest wall puncture cannula, preventing complete retensioning of the lungs because the chest cavity is connected to the atmosphere. Our experience did not reveal arrhythmias or pulmonary edema.
Thoracic placement time is prolonged, and Hansen et al. showed a mean postoperative placement time of 3.14 days (1-10 days) in 146 patients undergoing medical thoracoscopy and 6.47 days (1-19 days) in those given pleural fixation. Our time to placement ranged from 1 to 8 days with no delay in extubation. Chest drainage time was significantly longer when septic chest developed, even requiring surgical treatment.
In addition, subcutaneous emphysema, fever after talc pleural fixation, local infection of the incision, abnormal skin sensation of the incision, and implantation metastasis of the tumor chest can occur, and we reported 6 cases of subcutaneous emphysema, which was not treated and later absorbed by itself; 2 cases of pain during chest wall trocar placement, 12 cases of slight pain on biopsy, and 28 cases of postoperative wound pain; 1 patient with heavy adhesions had intraoperative bleeding of about 150 ml and local The bleeding was stopped after injection of epinephrine saline, and the vital signs were stable; 6 cases of postoperative fever occurred on the second postoperative day, mostly within 38℃, only 1 case reached 39℃, and the body temperature dropped to normal level on the third day; no wound infection occurred.
In conclusion, endoscopic thoracoscopy is a safe invasive examination with different reported complication rates of 3-22.6%, but serious complications are rare, and the reported mortality rate is 0.01-0.6%.
Third, the clinical application of internal thoracoscopy
(A) Diagnosis of unexplained pleural effusion
Clinically, it is common that patients with pleural effusion cannot be diagnosed after sufficient diagnostic examinations, including thoracentesis and pleural biopsy, and internal thoracoscopy can help to diagnose such patients. We performed thoracoscopy on 60 patients with unexplained pleural effusion and found 32 cases (53.3%) of malignant tumors, 16 cases (26.7%) of tuberculosis, 5 cases (8.3%) of negative findings or chronic inflammation, 4 cases (6.7%) of pneumonia combined with pleurisy, and 3 cases (5%) of severe adhesions where the chest wall could not be seen. Among the malignant tumors, there were 11 cases of adenocarcinoma of the lung, 6 cases of squamous carcinoma, 1 case of lymphoma, 3 cases of small cell carcinoma, 3 cases of pleural mesothelioma, 3 cases of breast cancer metastasis, 1 case of kidney cancer metastasis, and 4 cases of unknown primary focus.
(II) Diagnosis and treatment of malignant pleural effusion
Malignant pleural effusion is the main diagnostic and therapeutic indication for medical thoracoscopy. The analysis of 208 patients with malignant pleural effusion (58 cases of diffuse pleural mesothelioma, 29 cases of lung cancer, 28 cases of breast cancer, 30 cases of other tumors, 58 cases of unknown primary foci, and 5 cases of malignant lymphoma) showed that the diagnostic positivity rate of pleural fluid cytology was 62%, pleural biopsy was 44%, and internal thoracoscopy was 95%, the latter being significantly higher than the former two and higher than the positivity rate of the former two combined (74 The latter was significantly higher than the first two and higher than the first two combined (74%), with a total positive rate of 97% for all methods combined. A retrospective analysis of 146 medical thoracoscopic findings showed that for malignant pleural effusions, the sensitivity of medical thoracoscopy was 88% and the specificity was 96%.
The false negative results of endoscopic thoracoscopy may be related to the following factors: inadequate or unrepresentative biopsies, operator inexperience, and inability to visualize tumor tissue due to thoracic adhesions. In metastatic malignant pleural effusions, blind examination of the mural pleura has a low confirmation rate, and the mural pleura is often not involved in approximately 30% of patients, so direct visual biopsy of the visceral or diaphragmatic pleura may confirm the diagnosis. In addition, because of the relatively large size of the specimen for thoracoscopic biopsy, it is relatively easy for the pathologist to specify the origin of the tumor tissue.
For malignant pleural effusions, pleural fixation can be performed by uniformly spraying decottonized talcum powder on all parts of the pleura under direct medical thoracoscopy, which is the traditional alternative to pleural fixation. For some patients with non-neoplastic recurrent pleural effusions, such as celiac disease, they can also be treated by talc pleural fixation through medical thoracoscopy. Larger malignant tumors of the pleural wall can also be treated by microscopic interventions to reduce the tumor load, such as: argon knife, high-frequency electric knife, and laser. For single benign pleural mesothelioma in chest wall, if the tumor is considered as benign mesothelioma, it can be completely resected directly under medical thoracoscopy, which can achieve the goal of cure.
(iii) Diagnosis and treatment of tuberculous pleural effusion
Some authors believe that tuberculous pleurisy can have a 70-90% positive rate by blind pleural biopsy and that medical thoracoscopy is usually not necessary to diagnose tuberculosis. However, a study from South Africa showed that the diagnostic rate of thoracoscopy was 98%, while the positive rate of pleural biopsy was 80%. Therefore, the diagnosis of TB pleurisy by endoscopic thoracoscopy is also of great clinical value. In addition, the high rate of positive TB cultures of thoracoscopic biopsy tissue provides the possibility of performing antituberculosis drug susceptibility testing, which may have some impact on treatment and prognosis. Another study on hormonal treatment of tuberculous pleurisy found that complete drainage of pleural fluid during thoracoscopy improved symptoms better than any subsequent treatment, possibly due to improved adhesions within the pleura and adequate drainage of pleural fluid by thoracoscopy. Internal thoracoscopy can drain the pleural fluid at one time, rapidly remove the pleural fluid, relieve local blood and lymphatic circulation disorders, and promote exudate absorption; remove the pleural fluid, eliminate the stimulation of the pleura, and avoid pleural hypertrophy; flush out the pleural proteins, reduce the adhesive osmosis pressure in the pleural cavity, and alleviate pleural fluid exudation; release the pleural fluid and flush the pleural cavity, flush out the inflammatory media in the pleural cavity, reduce the inflammatory response of the pleura, and reduce exudation; cut the adhesions to prevent the division of the pleural cavity and facilitate the drainage of pleural fluid. Injecting anti-tuberculosis drugs such as isoniazid into the pleural cavity is prohibited to avoid aggravating pleural adhesions and hypertrophy.
(D) Treatment of pus thorax
For early abscess thorax (within 2 weeks of onset, without serious pleural adhesions), endoscopic thoracoscopy can be effective treatment, and fibrous-like changes can be clamped with biopsy forceps to change the pleural cavity from multiple rooms to one cavity, which is conducive to successful drainage and flushing, so if patients suitable for indwelling closed thoracic drainage should undergo thoracoscopy at the same time. For severe thoracic adhesions and mechanized lesions, surgical treatment is necessary.
(E) Treatment of pneumothorax and bronchopleural fistula
For spontaneous pneumothorax, lesions of the lung and pleura can be easily observed with medical thoracoscopy before the insertion of a closed chest drain. According to the microscopic observation, the lungs are classified into the following stages according to Vanderschueren classification: stage I with normal microscopic lungs; stage II with visible pulmonary pleural adhesions; stage III with small pulmonary blisters (≤2 cm in diameter); and stage IV with a large number of pulmonary blisters (diameter >2 cm) microscopically. Although obvious lesions can be detected by VATS or open-heart surgery, some pulmonary blisters or pleural fistulas can also be detected by medical thoracoscopy. Larger fistulas caused by post-surgery or trauma, etc. can be filled with a cell-free tissue filler after the application of silver nitrate. Pulmonary blister coagulation or decottonized talc pleural fixation can be performed by endoscopic thoracoscopy. Decottonized talc pleural fixation is the traditional management method with a recurrence rate of less than 10% and only 4-10% of cases requiring surgery. Stage IV patients with a large number of pulmonary blisters require VATS or surgery.
(F) Treatment of hemothorax
When the hemoglobin concentration in the pleural fluid exceeds more than half of the simultaneous hemoglobin of own blood, it is called hemothorax, which is not only seen in trauma, but also due to the rupture of the adhesion band containing blood vessels caused by pneumothorax. If no surgical treatment is required, diagnosis and treatment can be performed through medical thoracoscopy. The bleeding site can be found microscopically and then the bleeding can be stopped by electrocoagulation, etc. Sometimes the bleeding site cannot be found after entering the scope, and if no obvious bleeding is observed for half an hour, closed chest drainage can be placed, and hemostasis can also be achieved by the lung expansion through its own compressive effect. In case of continuous rapid bleeding caused by larger vascular injury, surgical thoracoscopy or open-heart surgery should be adopted.
(VII) Diagnosis and treatment of pleural effusion due to other etiologies
For patients with pleural effusion that is neither tumor nor tuberculosis, medical thoracoscopy can provide microscopic clues to find the etiology, such as rheumatoid pleural effusion, pleural fluid due to pancreatitis, cirrhotic pleural effusion, spread of peritoneal effusion or trauma. These etiologies can usually be diagnosed with a history, pleural fluid analysis and physical and chemical examination, but in patients in whom the diagnosis cannot be confirmed, medical thoracoscopy can help to establish the diagnosis. When it is not clear whether the pleural effusion is secondary or of primary pulmonary origin, e.g., pulmonary fibrosis or pneumonia, thoracoscopy and biopsy can clarify the diagnosis. For recalcitrant hepatogenic, nephrogenic and cardiogenic pleural effusion for which medical treatment is ineffective, thoracoscopic treatment is also feasible, and pleural atresia is performed to aspirate the pleural fluid (the method is the same as pleural atresia for malignant pleural effusion).
(H) Diagnosis of idiopathic pleurisy
Even after comprehensive pleural effusion examination and thoracoscopic biopsy, some patients with pleural effusion cannot be clearly diagnosed as the cause, and the pathological diagnosis is non-specific pleuritis (non-specific pleuritis). 8.3% progressed to neoplasia, and the proportion of idiopathic pleurisy of unknown etiology was eventually found to be 25%, similar to that reported by Hansen (23%). Therefore, the majority of patients with non-specific pleuritis diagnosed by thoracoscopic pathology can find an etiology, and only some of them have no etiology and can be clinically referred to as true “idiopathic pleuritis” with a benign course.
IV. Summary
As a safe and effective minimally invasive diagnostic and treatment technique that can be operated by respiratory physicians, internal thoracoscopy is of great clinical value for the diagnosis and treatment of pleural diseases such as pleural effusion and pneumothorax. The accuracy rate is almost 100%. It helps to clarify the etiology of pleural diseases and determine the prognosis of malignant effusions as well as to formulate the corresponding treatment plan. ). It is believed that in the near future, medical thoracoscopy will become a must-have and practical treatment technique for respiratory physicians.