Around 400 B.C., the ancient Greek physician Hippocrates suggested inserting a tube into the larynx to save a choking patient, which was the earliest prototype of a rigid scope. 1897 German scientist Killian first reported the use of a rigid esophagoscope to remove a bony foreign body from the trachea, which started the history of rigid scopes inserted into the trachea and bronchi for endoscopic manipulation. 1968 American physician Jackson improved the rigid tracheoscope and developed a standardized operating protocol. By the 1960s, rigid bronchoscopy was used for the diagnosis and treatment of lower respiratory tract diseases in all countries [1].
However, because rigid bronchoscopy requires general anesthesia, it is extremely inconvenient for clinical application and has limited visualization of bronchial lesions, so it was gradually replaced by soft bronchoscopy after the 1970s. Since the rise of bronchoscopic interventions in the 1980s, TV rigid bronchoscopy has been gradually favored by many physicians again, and rigid bronchoscopy has accounted for more than 80% of bronchoscopy in Germany, and with the development of electronic technology, the images of rigid bronchoscopy are clearer and easier to preserve. The rigid bronchoscope keeps the airway open and has a side hole at the operating end to connect to the ventilator, so the rigid bronchoscope is also called a “ventilating bronchoscope”. The modern value of the rigid scope is that it serves as an interventional channel allowing access to the airway for flexible bronchoscopes and other instruments, greatly broadening its scope of application to allow stent release, laser ablation, argon plasma coagulation (APC), foreign body extraction and cryopreservation under direct vision. Thus, scleroscopy is the main tool of modern interventional pulmonology, an ancient new technology that respiratory physicians should master and has broader application prospects. Today, RB is increasingly applied by interventional pulmonologists in Europe and the United States, and domestic specialists are also applying this bronchoscopic technique to provide timely and effective treatment for patients with central airway disease. The combined application of Flexible Bronchoscopy (FB) and RB presents unparalleled advantages in the management of complex airway diseases [2].
The light-guiding system of modern rigid bronchoscopes is a distal illumination guided and reflected through the wall of the tube, thus providing the operator with a clearer view of the pharynx and even the airway directly through the lumen for intubation, suction and foreign body management. The observation eyepiece makes the use of light sources and the clarity of the field of view much better, while the eyepiece can also be connected to a TV system for group observation and video recording. The video system provides magnified images of various angles to view the trachea, main bronchus and 5 lobar bronchi. Other facilities such as biopsy forceps and suction tubes can also be used to work through the scope sheath. Nowadays, soft bronchoscopes are mostly applied through rigid tracheoscopes to view the more distal as well as the upper lobe bronchi with large curvature.
The advantages of RB over FB include the ability to maintain airway ventilation, management of hemoptysis, shorter intervention time, and access to large biopsy specimens. general anesthesia during RB avoids unnecessary patient movement, thus making the patient more comfortable throughout the procedure. Patient selection and rehearsal of the procedure is an important part of preoperative preparation, which helps the anesthesiologist and endoscopist to anticipate and prevent possible complications. Although RB under general anesthesia is a safe procedure in the hands of experienced surgeons, most patients who potentially benefit from this procedure are often exposed to the risks that general anesthesia poses to the body.
The application of rigidoscopy is not yet widespread in China, and even some experts are opposed to it. In recent years, the authors have been involved in a number of medical errors related to tracheoscopic procedures, and some tragedies could have been avoided if rigid scopes had been performed, so it is imperative to promote the use of TV rigid bronchoscopy.
Rigid microscopy has an irreplaceable role in the interventional treatment of airway diseases [3], including the removal of complex airway foreign bodies, management of severe airway stenosis or obstruction, airway hemorrhage, endoluminal thermal ablation therapy such as laser, microwave, argon plasma coagulation (APC), endoluminal cryotherapy, and placement and removal of endotracheal stents.
After years of exploration and efforts, the authors have more experience and knowledge about the clinical application of rigid bronchoscopy, which we would like to share with our colleagues here.
1.Simple and easy operation of rigid bronchoscope
Rigid bronchoscopy is simple and easy to operate under general anesthesia, as long as there is an anesthesiologist to cooperate. The traditional rigid bronchoscope insertion has direct insertion and direct laryngoscopy-guided insertion, but recently the authors adopted the “Wang’s insertion method”, which is a soft-scope guided insertion method [4]. This method is a method gradually developed by the authors in clinical practice, which is simple and fast. During operation, the sheath is placed directly on the flexible mirror and the operation is observed directly with the video monitor of the flexible mirror, without using the eyepiece of the rigid bronchoscope and without connecting the video monitor of the rigid bronchoscope. The insertion part of the soft scope is slightly shorter than the insertion part of the rigid bronchoscope to facilitate the observation of the rigid bronchoscope entering the airway, and the rest of the sequence is the same as the direct insertion method. The end of the rigid bronchoscope can be directly connected to the anesthesia machine to ensure that the oxygen supply is not interrupted during the insertion of the rigid bronchoscope. This method is suitable for patients with a combination of soft and rigid bronchoscopes, eliminating the need to transfer the video monitor back and forth and saving a lot of trouble. The soft scope can also be used to aspirate secretions directly from the airway, making it easier to keep the lens clear. After the sheath is inserted into the trachea, the soft scope can be used for intervention directly.
2, rigid bronchoscopy under general anesthesia, can ensure the oxygen supply
Rigid bronchoscopy requires close cooperation with a skilled anesthesiologist [5,6]. Controlled mechanical ventilation is the complete control of the patient’s spontaneous breathing, supplemented with inotropes, and is indicated for patients in good physical condition and with strong airway reflexes. Adjunctive mechanical ventilation requires partial preservation of the patient’s voluntary breathing, especially in patients with severe airway obstruction and respiratory distress, and the amount of anesthetic dose should be strictly controlled to avoid causing cardiac function depression and blood pressure drop. After a period of operation, which may cause CO2 retention, the posterior hole of rigid mirror should be closed and manual balloon compressions should be activated to promote exhaustion. Autonomic breathing is usually done near the end of the operation, when the infusion of intravenous anesthetics is stopped, and the rigid scope can be pulled out when the patient’s autonomic breathing is fully restored and the oxygen saturation is maintained at 95% or higher. For patients with longer operation time and CO2 retention, after the tracheoscopic operation is stopped, the rigid scope is pulled out and the tracheal intubation is inserted, and mechanical ventilation is continued in the recovery room until CO2 is reduced to normal.
3. rigid tracheoscope in laryngeal stenosis, obstructive laryngeal carcinoma or subglottic stenosis
Previously, it was thought that high airway obstruction, especially lesions within 2 cm of the subglottis, were not suitable for rigid tracheoscopy, but in reality, rigid tracheoscopy is one of the best methods to treat such diseases.
In recent years, the authors have treated about 50 patients with high airway obstruction, including 2 cases of hypopharyngeal cancer, 4 cases of laryngeal cancer, 20 cases of thyroid tracheal invasion and other subglottic tumors and stenoses, all of which were not suitable for surgery after surgical consultation and were successfully treated by rigid bronchoscopy. For supraglottic tumors, a rigid tracheoscope can be inserted into the oral cavity without inserting the vocal canal, and an assistant assists in fixing the sheath. The front end of the sheath is aligned with the tumor for electrocannulation, APC and CO2 freezing. The tumor can be removed directly with the front end of the sheath, or the normal vocal fold can be protected with the bevel of the sheath, and the affected lesion can be removed with APC or freezing. The authors also successfully performed photodynamic therapy for three patients with laryngeal cancer under the protection of rigid mirror without serious complications such as vocal fold edema.
4. Rigid microscopy can remove intra-airway tumors quickly, safely and effectively
For large tumors in the central type airway, especially for patients with severe airway stenosis, rigid microscopic operation should be preferred. Such patients are usually difficult to lie down, and the insertion of rigid scope under general anesthesia can ensure the patient’s ventilation and allow various operations to be performed comfortably. Usually the rigid scope is used as a channel and to ensure ventilation. If the tumor is located in the main airway, it can be operated with various rigid instruments or soft-scope instruments; if the tumor is located in the bronchus, it is better to combine with electronic bronchoscopy to perform various operations.
Removal of tumor in the airway by rigid microscopy is fast, safe and effective. There are also many methods, such as direct eradication by rigid microscope, optical biopsy forceps, electrocircular condenser, thermal ablation (laser, microwave, APC), freeze extraction, etc. Which methods are appropriate to use need to consider the proficiency of endoscopic techniques, existing equipment conditions, etc. In the early stage, our hospital mainly adopted APC ablation method, but it was time-consuming, laborious and inefficient. Later, when it was combined with CO2 freezing, the efficiency was greatly improved, but complications such as bleeding increased. In the last two years, due to the continuous maturation of the technology, the utilization of the electric coiler and the direct eradication of the rigid mirror is increasing and the efficiency is greatly improved. Rigid microscope eradication is to directly eradicate the tumor using the semi-arc-shaped front end of rigid microscope and then remove the tumor using biopsy forceps. Cryotomy is to place the metal head of the frozen probe on the surface of the tumor or advance it into the tumor so that it can produce the maximum volume of ice balls around it, and remove the probe and its adherent tumor tissue in the frozen state. The frozen tumor should be large enough (do not freeze the wall of the tube) to remove all the tumor from the lumen with the least number of freeze retrievals. Freezing through a rigid microscope can be performed repeatedly and faster. Therefore, rigid microscopy is preferable for all malignant tumors with more than 75% airway stenosis, and the degree of tracheal obstruction, shortness of breath index, and KPS score are significantly improved after treatment [7].
However, each method has advantages and disadvantages and requires flexible and integrated application. For endotracheal or wall tumors, direct eradication with rigid microscope is suitable, followed by rapid removal of the tumor with rigid biopsy forceps or freezing to avoid asphyxia; for tumors with a tip or long tumor, direct excision with electric trap or optical biopsy forceps is suitable; for tumors with brittle surface and easy bleeding, APC is suitable to stop bleeding first and then freeze the tumor in combination with freezing; for tumors with diffuse tumor and not easy bleeding, freezing can also be used directly. For large tumors with wide base and rich blood flow, especially those with pulmonary atelectasis, preoperative pulmonary artery embolization is preferable to block the blood supply and reduce intraoperative bleeding.
The authors have retrospectively analyzed 81 cases (35 primary tumors and 46 secondary tumors) of central intra-airway malignancies treated by rigidoscopy [7], with 97.1% of intermediate and advanced tumors (stage III-IV). 181 rigidoscopic operations were performed in 81 patients, and 65.2% of patients underwent only one rigidoscopic treatment. The degree of airway obstruction, KPS, and shortness of breath index were 77.0±9.9%, 50.9±2.2, and 3.1±0.1, respectively, before and 16.4±2.5%, 75.4±1.8, and 1.1±0.1, respectively, after rigid microscopy, all at P<0.01. The results showed that rigid microscopy could rapidly and safely remove central-type intra-airway tumors, and combined with APC could also rapidly coagulate The combination of APC can also rapidly coagulate the tumor and hemostasis, relieve airway obstruction, and improve the survival quality of patients, which is an ideal treatment method for large intra-airway tumors.
Generally, if the airway is more than 50% blocked or the tumor length is more than 2cm, it is better to perform tracheoscopy and treatment under general anesthesia. If rigid scope is not available, a tracheal intubation tube of size 8 or above can be used instead of rigid scope, followed by a three-way tube for operation under mechanical ventilation.
The authors have compared the treatment effect of rigid scope combined with electronic bronchoscope (group A) and electronic bronchoscope alone (group B) [2], and the number of bronchoscopic examinations in group B was about 1.8 times more than that in group A. Because of the reduced number of operations in group A, the pain of patients was also greatly reduced. the range of single ablation in group A was larger than that in group B, i.e., the range of ablation in group A was about 4/5, while that in group B was about 2/3. Generally, for tumors blocking one side of the bronchus (unilateral total pulmonary atelectasis), all the tumors in the lumen can be removed in about 1 hour using rigid bronchoscopy combined with freeze extraction, while APC with soft microscopy alone takes 1.6 hours.
In recent years, authors have also implanted radioactive particles 125I via tracheal puncture under rigid microscopy, which should be extremely safe and accurate.
Scleroscopy combined with electronic bronchoscopy has significant efficacy in obstructive pulmonary atelectasis, especially for total pulmonary atelectasis, which is significantly better than that of pulmonary segmental atelectasis [8]. In our group of 20 patients with total pulmonary atelectasis, 55% of the whole lungs were reopened after rigidoscopic treatment, 35% were partially reopened, and only 10% failed to be reopened. 6 cases of tumors located in the right middle segment were all cleared, and the atelectasis caused by the middle and lower lobes disappeared. In the 31 patients with segmental atelectasis, 38.7% of all patients had reopened, 22.6% had partially reopened, and 38.7% had failed to reopen after rigidoscopic treatment. Due to the limitations of the current bronchoscopic insertion end diameter and operating instruments, it is difficult to remove tumors located in the bronchi below grade 4, and the resulting atelectasis is also difficult to be effective. In this paper, one fatal hemorrhage occurred intraoperatively because the tumor encroached on the right middle segment of the bronchus, and the vessel ruptured and hemorrhaged after the tumor was removed. Three other cases of hemorrhage occurred during the biopsy of the opening of the dorsal segment of the lower lobe. There were also 2 cases of hemorrhage due to excessive tumor clearance, which removed all the tumors in the obstructed grade 5 bronchi, resulting in death by hemorrhage at 1 week and 3 weeks after surgery, respectively. In addition, metastatic tumors are richly vascularized and may cause bleeding during biopsy. Therefore, the tumors in the lungs should not be removed completely, but can be combined with drug injection and radiotherapy/chemotherapy particle implantation to eliminate the residual tumors [10].
5. rigid microscopy in benign airway stenosis
TV rigidoscopy can also be used in benign airway stenosis [9], and the most common lesions in this group are airway tuberculosis, granuloma formation after stent placement, and post-traumatic scar stenosis. Severe airway scar stenosis lesions are preferable to first perform airway balloon dilation or take APC, and then combine it with freezing to enlarge the lumen and use freeze-thaw for residual sites. Large intra-airway polyps or foreign bodies can be removed by large biopsy forceps bite, high-frequency electric knife traps, CO2 freezing and APC cautery, which can be performed in combination. For more special foreign bodies in the airway (such as long nails, glass beads, animal bones, etc.), they can be removed under hard microscopy by freezing sticky, clamping and other methods.
6.Placement and removal of endotracheal stent under rigid microscope
(1) Placement of stent
In addition to tumor removal under rigid microscopy, endobronchial stents can be placed under rigid microscopy. Silicone stent requires placement under rigid microscope, while metal stent can be placed under soft microscope and rigid microscope, especially bifurcated stent is safer and more reliable to be placed under rigid microscope. The authors have reported the removal of tracheal stents esophageal stents in 5 cases each, placement of L-shaped stents in 6 cases, implantation of radiotherapy/chemotherapy particles in 6 cases, and photodynamic therapy (PDT) in 3 cases [10]. In some critically ill patients, removal or placement of stents under general anesthesia is safer [11, 12]. In five cases of esophageal stents that were difficult to remove under gastroscopy, the stents were easily removed by inserting the rigid scope directly into the esophagus under general anesthesia. pDT was mainly used in three cases of pharyngeal tumors that were difficult to treat under local anesthesia because of severe blockage of the vocal cord by the mass, then the anterior segment of the rigid scope was first ridden across the vocal cord under general anesthesia, and the tumor was quickly removed by ventilation and treatment at the same time
In the early days of the authors, the bifurcated stent needed to be placed under C-arm guidance, but nowadays, it is mostly placed under rigid microscope which is safer and more accurate and painless for patients.
(2) Removal of stent
Granulation tissue proliferation after stent placement (especially metal bare stents) requires repeated bronchoscopic interventions; therefore, it is important to remove the stent at the right time [11]. Retrievable stents can be removed with a soft microscope, whereas bare stents require granulation clearance, stent fragmentation, and then stent monofilament extraction combined with APC and cryopreservation for the ultimate goal of cure. The removal of bare stent is preferable to rigid microscopy.
7.Removal of foreign body in the airway with rigid tracheoscope
Long-term retention of foreign bodies in the airway often causes airway narrowing or obstruction. Due to the different shapes and sizes of foreign bodies, although there are a variety of foreign body removal forceps, but still can not meet the clinical needs. In recent years, the application of rigid microscopic techniques such as optical foreign body forceps, CO2 freezing, and APC [13,14,15] has made it possible to remove foreign bodies in the airway easily and quickly. The authors have removed more than 20 types of foreign bodies such as denture, pig bone, chicken bone, fish bone, pencil, nuts, jelly, and nails that had been retained in the bronchus for many years, solving the patients’ problems for many years. The foreign body that stays in the bronchus for a long time is often covered with granulation tissue on the surface. It is advisable to remove the excess tissue on the surface with APC first, expose the foreign body fully, then remove the foreign body with foreign body clamp or freezing, and then give freezing and thawing to the residual part to prevent the regeneration of granulation.
8.Management of complications
Rigid tracheoscopic operation is performed under direct vision, which is generally safer and has fewer complications. However, the ease of rigid mirror insertion should be evaluated before surgery. In recent years, the authors have performed nearly 700 rigid bronchoscopy operations, and only 3 cases failed to insert the rigid bronchoscope due to scar contracture of the neck after tracheotomy, while the other cases were all successful; 3 cases lost their teeth during the operation (the teeth were loose before the operation). For those who have loose teeth before surgery, they should declare in advance that it may cause tooth loss to avoid unnecessary disputes. There was not a single case of death related to rigid mirror operation.
After the operation, the patient should be bedridden for 6 hours, and the occurrence of laryngeal edema should be closely observed, and if necessary, glucocorticoids and diuretics should be given quickly.
The rigid microscope operation is relatively safe during the procedure. Continuous APC cautery tends to cause hypoxemia [16]. Intraoperative hypoxia occurred in 73.3% of our group, but after the operation was stopped and oxygen was administered, the oxygen saturation would rise quickly and the operation could be continued after it returned to normal. Masses that cause severe airway obstruction should be removed as soon as possible to prevent asphyxia. In the case of major bleeding in the airway, continuous negative pressure suction should be applied so that the blood clot does not block the airway, and if necessary, a double-lumen balloon catheter or pulmonary artery embolization should be used instead to stop the bleeding. These methods have not been used in this paper. There was no 1 case of severe hypoxic death.
Ultrasonic endoscopy has rapidly emerged in recent years, but due to the thicker insertion end of the endoscope, the light microscope is not direct vision, the patient is more uncomfortable during insertion, such as operating under a rigid microscope is extremely safe and painless.