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 all layers of the pleura makes the application of this technique of great practical importance for the diagnosis of pulmonary pleural diseases.
I. Concept of internal thoracoscopy
(A) History of endoscopic thoracoscopy
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-assistedthoracicsurgery (VATS) that we see now. The use of surgical thoracoscopy has led to a greater understanding and use of “medical thoracoscopy” by pulmonologists. According to a 1994 survey of 1000 pulmonologists in the United States, approximately 5% of U.S. pulmonologists used internal thoracoscopic techniques for pulmonary pleural disease. In Europe, thoracoscopic techniques are included in pulmonary training programs. In China, several hospitals have also used 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 begun to use this flexible endoscope (Flexirigidthoracoscopy, or semi-rigidthoracoscopy) in clinical practice.
(B) Differences between medical and surgical thoracoscopy
Thoracoscopy provides the clinician with the opportunity to look directly at the lesion in the pleural cavity and possibly diagnose and/or treat the lesion. There is no clear concept of medical-surgical thoracoscopy, and the main differences between the two are the following.
(i) medical thoracoscopy is performed by a pulmonologist or respiratory endoscopist in a tracheoscopy suite, whereas surgical thoracoscopy is performed by a thoracic surgeon in an operating room.
(ii) medical thoracoscopy is performed by 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 anesthesia and double-lumen tracheal intubation to ensure operation on the affected side.
(③) Internal thoracoscopy rarely uses disposables and does not require general anesthesia, so the cost is significantly lower than surgical thoracoscopy; 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, whereas surgical thoracoscopy department can complete operations such as lesion removal and pleural release for severe adhesions.
Based on these differences, there is no evaluation of the advantages and disadvantages of medical and surgical thoracoscopy, because each has its own indications. Here, we mainly introduce the clinical application of medical thoracoscopy so that more respiratory physicians can understand and use this technology.
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 source and image system, biopsy forceps and postoperative chest drainage required. All examination thoracoscopes vary from region to region depending on the conditions, and there are three main types as follows.
①General thoracoscopy, which is the rigid thoracoscope used for surgical thoracoscopy, and experienced physicians who also use bendable bronchoscopes to observe changes in the thoracic cavity.
② Bronchoscopy instead of thoracoscopy: some authors in China use this method, which allows the diagnosis of pleural diseases in areas where no thoracoscopic equipment is available. 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 biopsies are taken smaller.
③Front-end bendable electronic thoracoscope: This is a new type of equipment appeared in recent years, its rigid rod part has the easy operability of ordinary rigid thoracoscope, while the front-end bendable part can observe the 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) Procedure
1.Select 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 the selection of the puncture site for trocar placement via chest wall ultrasound is both safe and effective without the need for preoperative artificial pneumothorax, and ultrasonography saves time, so ultrasound localization of the puncture needle can replace medical thoracoscopy Pre-op pneumothorax. Usually the patient is in the healthy-side position, and the incision is chosen in the 4th to 8th intercostal space of the chest wall in the axilla of the affected side, commonly in the 6th to 7th intercostal space.
2.Local anesthesia: 5%-20 ml of 1% lidocaine is given at the puncture site for local anesthesia, and midazolam and fentanyl can be given intravenously for sedation if the pain is obvious, and cardiac, electrical, blood pressure and oxygen saturation monitoring are 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 stripped to the pleura, a puncture cannula is placed, and the thoracoscope is sent into the pleural cavity through the cannula to observe the visceral layer, wall layer, 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 the 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 fluid or recurrent benign effusion requiring pleural fixation, 3 to 5 g of sterilized dry talcum powder is commonly sprayed evenly into the pleural cavity through a rigid or bendable nebulizing device with an attractor. For patients with pneumothorax, 2~3ml of talcum powder is sufficient. Postoperative closed chest drainage needs to be left in place for negative pressure suction.
4.Postoperative: After the operation is completed, a closed chest drainage tube is placed via trocar, and X-ray is performed after the operation to understand the position of the tube placement and changes in the chest cavity.
Indications
Internal thoracoscopy is mainly used for diagnosis, but also for partial intrathoracic treatment. Its main indications are.
① pleural effusion for which the etiology cannot be clarified by various non-invasive methods.
②staging of lung cancer or pleural mesothelioma.
③Treatment of talc pleural fixation in patients with malignant effusion or recurrent benign pleural fluid.
(iv) For stages I and II in spontaneous pneumothorax, local treatment is also an indication for medical thoracoscopy.
⑤ Other indications include cases requiring biopsy in the diaphragm, mediastinum and pericardium.
In the medical thoracoscopy performed by Loddenkemper et al, pleural effusion accounted for up to 90% of the cases, while diffuse lung disease, mediastinal tumors, and pneumothorax accounted for very few cases, due to advances in imaging techniques, such as CT and MRI, fewer patients underwent thoracoscopy for localized lung lesions or chest wall lesions, and the ability to identify benign or malignant lesions through imaging changes; in addition, VATS can perform diagnostic examinations while clearing lesions; in addition, diffuse lung diseases can be diagnosed in part by the development of bronchoscopic TBLB, bronchoalveolar lavage, and high-resolution CT, e.g., histiocytosis X and idiopathic interstitial pulmonary fibrosis. Therefore, medical thoracoscopy is mainly used for the diagnosis of pleural effusion, which is the “gold standard” for the diagnosis of unexplained pleural effusion.
Contraindications
Internal thoracoscopy is a safe examination. 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 some authors using a platelet count of less than 40,000 as the threshold.
② hypoxemia.
③severe cardiovascular disease.
④ persistent uncontrollable cough.
⑤ Extremely weak individuals.
V. Complications and their prevention
Common complications include benign arrhythmias, mild hypertension or hypoxemia, which can be almost 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 a major cause of death and requires emergency open-heart surgery to stop the bleeding, a complication that has been shown to be rare in several studies.
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 equal amount of gas will soon enter the chest cavity from the chest wall puncture cannula, preventing complete retensioning of the lungs because the chest cavity is connected to the atmosphere.
The duration of thoracic placement is prolonged, and Hansen et al. showed a mean postoperative placement time of 3.14 days (1 to 10 days) in 146 patients undergoing medical thoracoscopy, and 6.47 days (1 to 19 days) in those given pleural fixation. Similar to Blanc’s observations in 168 medical thoracoscopies, the time to tube placement was 4.1 ± 0.2 days after 132 diagnostic examinations and 5.6 ± 0.4 days after diagnostic and pleural fixation treatment. The duration of chest drainage was significantly longer when an abscess chest was present, even requiring surgical treatment.
In addition, subcutaneous emphysema, fever after talc pleural fixation, local infection in the incision, abnormal skin sensation in the incision, and implantation metastasis in the tumor chest can occur; therefore, for patients with pleural mesothelioma, local radiotherapy can be performed 10 to 12 days after thoracoscopic surgery to prevent tumor implantation at the puncture site.
In conclusion, endoscopic thoracoscopy is a safe invasive examination with different reported complication rates ranging from 3% to 22.6%, but serious complications are rare, and the reported mortality rate is 0.01-0.6%.
Sixth, the application of internal thoracoscopy in the diagnosis and treatment of diseases
(A) Unexplained pleural effusion
Clinically, patients with pleural effusion cannot be diagnosed after a large number of diagnostic examinations, including thoracentesis and pleural biopsy, so endoscopic examination can help to diagnose such patients.
(II) Cancerous pleural effusion
Cancerous pleural effusion is the main diagnostic and therapeutic indication for medical thoracoscopy. Internal thoracoscopy helps to stage lung cancer, diffuse malignant pleural mesothelioma, and metastatic cancer. Internal thoracoscopy can reveal whether the tumor has invaded the pleura, whether it is secondary to venous or lymphatic obstruction, or whether it is a parapneumonic effusion, and therefore the examination may allow avoidance of open-heart surgery or proper evaluation of the indication for surgery; in addition, for patients with malignant effusions confirmed by pleural fluid cytology or pleural biopsy, thoracoscopy can obtain larger tissue for histologic staging, and in Blanc’s study 16.7% of malignant pleural mesotheliomas were diagnosed as adenocarcinoma by thoracoscopy. In diffuse malignant pleural mesothelioma, endoscopic thoracoscopy can provide an early diagnosis and better histologic classification and fine staging because of its ability to obtain larger and representative pleural tissues. In addition, the finding of fibrous changes or calcifications, thickening or white plaques in the pleura can suggest asbestos exposure, and the finding of asbestos fibers by thoracoscopic lung biopsy or biopsy of specific lesions in the mural pleura supports benign asbestos-associated pleural effusion, but other diagnoses need to be excluded.
In metastatic malignant pleural effusions, blinded examination of the mural pleura has a low confirmatory rate, with the mural pleura often not being 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.
Breast cancer is the most common cause of metastatic pleural fluid, and detection of hormone receptors by testing thoracoscopic biopsy tissue may help in the determination of anti-hormonal therapy and prognosis.
For malignant pleural fluid, therapeutic thoracoscopy can be performed under direct vision by spraying talcum powder evenly over all parts of the pleura, which is the traditional alternative to pleural fixation. This approach is also effective in the treatment of celiac disease due to lymphoma. For some patients with non-neoplastic recurrent pleural effusion, such as celiac disease, it can also be treated by talc pleurodesis through medical thoracoscopy.
(iii) Tuberculous pleural effusion
Some authors believe that tuberculous pleural effusion can have a 70% to 90% positive rate by blind pleural biopsy, and that medical thoracoscopy is usually unnecessary to diagnose tuberculosis. However, a study of 40 cases from South Africa showed that the diagnostic rate of thoracoscopy was 98%, while the positive pleural biopsy rate 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, probably due to improved adhesions within the pleura and adequate drainage of pleural fluid by thoracoscopy.
(iv) Abscess chest
In early septic chest (within 2 weeks of onset and without severe pleural adhesions), endoscopic thoracoscopy can be an effective treatment, with biopsy forceps to clip fibrous-like changes that change the pleural cavity from multiple chambers to a single cavity, facilitating successful drainage and irrigation, and therefore should be performed concurrently with thoracoscopy in patients who are suitable for indwelling closed chest drainage. For severe thoracic adhesions and mechanized lesions, surgical treatment is necessary.
(V) Spontaneous pneumothorax
In 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, they are classified into the following stages according to the Vanderschueren classification: stage I with a normal microscopic lung; stage II with visible pulmonary pleural adhesions; and stage III with a small pulmonary blister (2 cm in diameter) microscopically. Although obvious lesions can be detected by VATS or open-heart surgery, some pulmonary blisters or pleural fistulas can also be detected by endoscopic thoracoscopy. Pulmonary blister coagulation or talcum powder pleural fixation can be performed through endoscopic thoracoscopy. Talcum powder pleural fixation is the traditional management method with a recurrence rate of less than 10% and only 4% to 10% of cases requiring surgery. Patients with stage IV have a large number of pulmonary blisters that require VATS or surgery.
(F) Pleural effusion due to other etiologies
For patients with pleural effusion that is neither neoplastic nor tuberculous, 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 for 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.
(vii) Idiopathic pleuraleffusion (idiopathic pleural effusion)
Even after comprehensive pleural effusion examination and thoracoscopic biopsy, some patients with pleural effusion are still unable to define the etiology, 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.
VII. Outlook
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. Through endoscopy, malignant or tuberculous effusions can be clearly identified or excluded with an accuracy rate of almost 100%; it helps to clarify the etiology of pleural diseases and the prognosis of malignant effusions as well as to formulate corresponding treatment plans; in addition, it is also of great significance for the treatment of pus and spontaneous pneumothorax; through endoscopy, talcum powder is blown into the chest cavity to treat malignant pleural fluid and recurrent benign effusions (e.g., celiac disease). It is believed that in the near future, medical thoracoscopy will become a must-have and practical treatment technique for respiratory physicians.