Fig. 2.1
Dr. Shigeto Ikeda, surgeon at the National Cancer Center, Japan, 1977 (Photography: Burt Glinn Magnum Photos)
The first commercially available flexible bronchoscope was manufactured by Machida in 1968 and comprised of over 15,000 glass fibers. Further revisions and improvements by Machida and Olympus allowed an enhanced working channel, image quality, and maneuverability.
The invention of the flexible bronchoscope represented a paradigm shift in the world of bronchoscopy. It was an easier procedure to perform than rigid bronchoscopy and allowed superior visualization of the distal airways. It continued to evolve with extensive technical and clinical applications. With Ikeda’s contribution, Pentax produced the first flexible video bronchoscope in 1987, where a miniature video camera at the tip of the bronchoscope replaced the fiber-optic bundle, allowing for the bronchoscopy team to watch the procedure on a screen with tremendous definition and record it for documentation and educational purposes [5].
A second paradigm shift occurred with the introduction of endobronchial ultrasound (EBUS) bronchoscopy, another form of flexible bronchoscopy.
The usefulness of radial probe EBUS was first reported by Hurter and Hanrath in 1992. They studied 74 patients with central tumors and 26 patients with peripheral carcinomas [6]. In 1996, Heinrich Becker demonstrated the great potential of EBUS in assessing tumor infiltration of the bronchial wall and parabronchial structures, including lymph nodes [7].
In the early 2000s, Yasufuku and colleagues were the first to describe the high diagnostic yield of convex probe EBUS, enabling real-time visualization and sampling of the mediastinal, hilar adenopathy and central lesions, changing the way we diagnose and stage lung cancer forever [8, 9].
Significant technological innovations over the last few decades such as laser therapy, argon plasma coagulation (APC), transbronchial cryobiopsy, and electromagnetic navigational bronchoscopy were specifically developed and designed to use with the flexible bronchoscope [10].
Description
The flexible bronchoscope constitutes a flexible hollow vinyl tube called the “insertion tube ” that contains optical fibers and a longitudinal working channel for suction and ancillary instruments.
The proximal handle contains a control lever to maneuver the distal end of the scope and control buttons for the camera and suction (Fig. 2.2).
Fig. 2.2
The bronchoscope handle with the control lever at the proximal end and working channel insertion point at the distal end
There are two light transmitting bundles and one viewing bundle. Each bundle contains up to 30,000 ultrafine glass fibers (8–15 μm). In the fiber-optic bronchoscope, the light entering to the system is internally reflected and emitted at the opposite end.
However, in the video bronchoscope, a charge-coupled device (CCD) has replaced the viewing bundle. The CCD converts energy from light photons into digital information allowing excellent quality image capturing.
The current flexible video bronchoscope’s outer diameter ranges from 2.8 mm for the ultrathin scope to 6.9 mm for convex probe EBUS.
The working channel ranges from 1.2 mm for the ultrathin bronchoscope to 3.0 mm for the therapeutic bronchoscope (Fig. 2.3).
Fig. 2.3
Distal ends of different bronchoscopes ranging from the therapeutic bronchoscope with a 3 mm working channel on left to the thin bronchoscope with a 1.2 mm working channel on the right
The length of the insertion tube ranges from 400 to 600 mm and the distal-end flexion angulation ranges from 120 to 210° in the latest generation bronchoscopes [11]. On the other hand, the distal-end extension angle ranges from 60 to 130° on the flexible bronchoscope (Fig. 2.4a, b). Of note, the flexible bronchoscope was designed to hold with the left hand since Dr. Ikeda was left-handed.
Fig. 2.4
(a) Distal end of the bronchoscope maximally extended at 130°. (b) Flexion of distal end of bronchoscope to 210°
Indications and Contraindications
Indications for flexible bronchoscopy are divided into diagnostic and therapeutic (Tables 2.1 and 2.2).
Table 2.1
Indications for diagnostic flexible bronchoscopy
Suspected malignancy | Lung nodule/mass, airway lesion, hilar or mediastinal mass/adenopathy, lung cancer staging |
Pulmonary infections | Pneumonia in immunocompromised host, cavitary lesions, non-resolving pneumonia, recurrent pulmonary infections |
Diffuse lung disease | Interstitial lung disease, pulmonary toxicity, suspected diffuse alveolar hemorrhage, inhalation lung injury |
Symptoms and signs | Hemoptysis, stridor, persistent cough, unexplained dyspnea, unilateral wheezing |
Abnormal chest imaging | Persistent lobar collapse, localized bronchiectasis, suspected airway obstruction/narrowing, suspected excessive expiratory airway collapse, tracheobronchomalacia |
Miscellaneous | Suspected aerodigestive fistula, bronchopleural fistula, chest trauma with suspected airway tear/injury, perioperative thoracic surgery, chemical and thermal burns of the airway, suspected foreign body aspiration, evaluation of posttransplant patients, endotracheal tube positioning |
Table 2.2
Indications for therapeutic flexible bronchoscopy
Central airway obstruction (CAO) | Benign disease: laser coagulation, radial cuts, electrocautery, balloon dilatation of stenosis/stricture |
Malignant disease: tumor debulking/resection, laser coagulation/ablation, argon plasma coagulation (APC), cryotherapy, photodynamic therapy, stenting (self-expandable stents) | |
Foreign body removal | Removal of aspirated foreign body or broncholith extraction |
Fiducial marker placement | Assisting in tumor localization for tumor resection or stereotactic body radiation therapy |
Hemoptysis | Coagulation via LASER/ APC or electrocautery of visible tumor/lesion, placement of airway blocker |
Tracheobronchial toilet | Therapeutic lavage in necrotizing pulmonary infections |
Bronchopleural fistula closure | Spigots, endobronchial vale placement, sealant placement |
Aspiration of cyst, drainage of abscess | EBUS-guided drainage of cysts and abscesses |
Difficult airway intubation | Awake intubation for difficult airway and guidance in percutaneous dilatational tracheostomy |
Bronchial thermoplasty | Treatment option in select asthmatics |
Endoscopic lung volume reduction | Endobronchial one-way valve placement in select patients with emphysema |
It is not uncommon that a diagnostic flexible bronchoscopy becomes both diagnostic and therapeutic at the same session, depending on unexpected findings that go undetected with pre-procedure imaging modalities or a change in the patient’s condition.
Increasingly, therapeutic flexible bronchoscopic interventions are being performed by pulmonologists. In our opinion, it is due to increased number of dedicated interventional pulmonology training programs and the more recent innovations in this field.
Flexible bronchoscopy, in general, has a great safety profile [1, 2]. Major complications such as bleeding, respiratory depression, cardiorespiratory arrest, arrhythmia, and pneumothorax occur in less than 1% of cases. Mortality is rare, with a reported death rate of 0–0.04% in more than 68,000 procedures [12]. Most contraindications are relative rather than absolute [12–14].
Absolute Contraindications
Life- threatening arrhythmia and/or hemodynamic collapse
Profound refractory hypoxemia/inability to oxygenate patient during the procedure
Lack of informed consent
Lack of capable bronchoscopist
Lack of adequate facility
Relative Contraindications (Risk-Benefit Assessment)
Bleeding diathesis : Platelet count less than 50,000/mm3, uremic platelet dysfunction, and INR > 1.5 are relevant when brushing or biopsies are considered [15, 16]. Papin and colleagues demonstrated significant incidence of bleeding in 24 patients who underwent transbronchial lung biopsy (TBLB) with mean platelet count of 30,000/mm3 [17]. Ernest and colleagues concluded that Clopidogrel use greatly increases the risk of bleeding after TBLB in humans and therefore should be discontinued 5 days before bronchoscopy with planned biopsies [18]. On the other hand, Herth et al. found that aspirin does not increase bleeding complications after TBLB [19]. A small case series by Stather concluded that proceeding to EBUS-TBNA without first withdrawing clopidogrel should only be performed in situations where the risk of short-term thrombosis is believed to outweigh the (theoretical) risk of bleeding [20].
Recent myocardial infarction or unstable angina: Most experts will postpone elective bronchoscopies for 6 weeks post-acute coronary syndrome [21].
Lack of patient cooperation.
Pregnancy.
Asthma attack.
Increased intracranial pressure.
Inability to sedate.
Procedure Preparation
Flexible bronchoscopy can be performed in the endoscopy suite, operating room, intensive care unit, or even emergency room:
- 1.
Equipment
The basic equipment needed is a bronchoscope and its accessories: light source and preferably a video monitor if available, BAL container, cytology brushes, biopsy forceps, needle aspiration catheters, syringes, normal saline aliquots, specimen containers, bronchoscope lubricant, bite block, suction apparatus, supplemental oxygen, continuous pulse oximetry, hemodynamic monitoring, and equipment for resuscitation including an endotracheal tube, laryngoscope, and chest tube insertion kit. Fluoroscopy can be valuable when performing TBLB and advanced diagnostic or therapeutic FB.
- 2.
Personnel
The bronchoscopist, registered nurse, endoscopy technician or respiratory therapist (RT), and the anesthesiologist or certified registered nurse anesthetist should all be familiar with the patient’s condition and the procedure being performed as well as appropriate handling of the specimens. This will maximize patient experience and outcome (Fig. 2.5).
- 3.
Patient Preparation
A consent form must be obtained after explaining the procedure, its indication, risks, and benefits.
The bronchoscopist must perform a thorough history and physical exam prior to proceeding. Chest imaging and diagnostic tests should be reviewed carefully.
A few important concerns to mention:
Nil per os (NPO): Indicated for 2 h for clear liquids and 6–8 h for solids prior to FB [22].
Electrocardiograms are generally indicated for patients with suspected or known cardiac history.
Spirometry is not indicated prior to proceeding with bronchoscopy [23].
Premedication with atropine or glycopyrrolate is not beneficial in reducing bronchoscopy-related cough or secretions [12, 13].
Prophylactic antibiotics: FB is a rare cause of bacteremia and endocarditis [24]. Prophylactic antibiotics are indicated in patients with mechanical valves and history of endocarditis.
Chest X-ray is indicated 1 h post-transbronchial lung biopsy (TBLB) to rule out pneumothorax [25]. Alternatively, a thoracic ultrasound exam, documenting sliding lung sign, will rule out pneumothorax post-TBLB. Kumar and colleagues performed a total of 379 FB and 113 TBLB. Chest US exam detected all cases of PTX, whereas CXR missed 1 PTX. The sensitivity, specificity, and overall accuracy for US were 100% as compared with the sensitivity of 87.5% and accuracy of 99.6% for the CXR group [26].
- 4.
Anesthesia and Monitoring
The current guidelines do not address the type of anesthesia needed for each procedure, but suggest that simple diagnostic FB procedures can be performed under local anesthesia or moderate conscious sedation. On the other hand, complex diagnostic and therapeutic bronchoscopy usually requires general anesthesia like total intravenous anesthesia (TIVA) [27].
The most used local/topical anesthetic for FB is lidocaine. Its plasma level of 5 μg/mL or dose greater than 8.2 mg/kg instilled in the airways can result with CNS toxicity (restlessness, slurred speech, seizure), cardiovascular toxicity (atrioventricular block, hypotension), and methemoglobinemia.
Common sedative and opioid combinations used during conscious sedation are midazolam and fentanyl. Propofol or, to a less extent, ketamine or dexmedetomidine coupled with fentanyl or remifentanil is used in TIVA (Fig. 2.6).
After FB procedure, patients are observed in the recovery unit until they meet discharge criteria. Written discharge instructions and contact information are provided to the patient.
Fig. 2.5
The bronchoscopy team in the procedure suite
Fig. 2.6
A bronchoscopy procedure in progress using ENB and radial EBUS through a laryngeal mask airway with general anesthesia
Technique of FB Procedure
Insertion route: According to an ACCP survey done in 1991, 33.8% of the total 871 responders/bronchoscopists preferred the nasal FB route, compared to 6.4% preferred oral route only and 42.6% had no preference [15]. Choi and colleagues in 2005 randomly assigned 307 patients to nasal vs. oral insertion route. They concluded that oral insertion of a flexible bronchoscope was associated with less discomfort for patients than nasal insertion, although the route of insertion had no significant effect on outcome [28]. Beaudoin and colleagues assessed the feasibility of using nasal route for linear endobronchial ultrasound performed on 196 patients where in 73.5% of patients, nasal insertion was possible. The author concluded that linear EBUS can be performed safely and with high accuracy via the nasal route [29].
When ready to proceed with FB, the patient should be placed in either a semirecumbent or supine position after IV access has been obtained. A topical anesthetic should be applied to the nasal passages and pharynx in case of nasal route insertion and only pharynx if oral route is chosen. Then, the bronchoscope is introduced either through the nose or mouth with a bite block in place to protect the bronchoscope. The oropharynx is examined, reaching the vocal cords, which are re-anesthetized topically. The vocal cords are examined for abduction and adduction. The bronchoscope is passed through the vocal cords to examine the tracheobronchial tree. We prefer to start with inspection of the normal airways, leaving the diseased area of interest to the end. A thorough, systematic approach to examine the airways is recommended. Description of airway configuration, mucosal membranes, secretions, location, extent, and size of the abnormality is very valuable. Luminal narrowing/obstruction whether intrinsic, extrinsic, combined, or dynamic should be described; its length and distance from the closest carina should be documented in the report since it is very valuable if surgical intervention may become an option.
Both diagnostic and therapeutic bronchoscopic procedures can be performed during flexible bronchoscopy. Lengthy, complex diagnostic and therapeutic procedures are better performed under IV general anesthesia.
Depending on the indication, the following diagnostic procedures can be performed: BAL, endobronchial or transbronchial biopsies, cytological washes or brushings, conventional TBNA, endobronchial ultrasound (EBUS) TBNA, radial probe EBUS, cryobiopsy, navigational bronchoscopy, and narrow-band imaging (NBI) bronchoscopy. Therapeutic procedures such as balloon dilatation, endobronchial laser ablation/coagulation, electrocautery, photodynamic therapy, brachytherapy, self-expandable stent placement, and endobronchial valve placement can all be accomplished through flexible bronchoscopy [12, 14].
Complications of FB Procedure
Flexible bronchoscopy, in general, has a great safety profile [1, 2, 30]. Major complications such as bleeding, respiratory depression, cardiorespiratory arrest, arrhythmia, and pneumothorax occur in less than 1% of cases [15]. Mortality is rare, with a reported death rate of 0–0.04% in more than 68,000 procedures [12].
It is important to mention that transient hypoxemia during and after bronchoscopy is the most common complication, especially when performing BAL in a patient with borderline cardiopulmonary reserve [2, 31]. Cardiac arrhythmia and risk of myocardial infarction are increased in elderly patients with cardiovascular comorbidities [32, 33].
Other complications of FB are adverse events of sedatives and narcotics, hypercapnia, hypotension, bronchospasm and laryngospasm, pneumothorax, and bleeding. Gas embolism has been reported with using argon plasma coagulation [34].
Basic Diagnostic Procedures
- 1.
Bronchoalveolar Lavage (BAL)
The bronchoalveolar lavage was first introduced to clinical practice by Reynolds in 1974 [35].
Standardization of BAL was addressed in a report by the European Respiratory Society task force in 1999. The report considers in detail the four main problems that prevent accurate quantification of components in alveolar epithelial lining fluid (ELF) using BAL:
- (a)
Unknown amount of dilution during lavage.
- (b)
Contamination of the ELF sample with material from the bronchi.
- (c)
Inadequate sampling due to incomplete mixing.
- (d)
Lung permeability varies allowing loss of introduced lavage fluid into the tissues and increased leakage of soluble components from the blood capillaries and tissues into the ELF [36].
- (a)
To perform a BAL, the bronchoscope is wedged in the target bronchus, while keeping the working channel in the lumen of the bronchus. A total of four aliquots (30–60 mL each) are instilled in the alveoli for a total of at least 100 mL and a maximum of 240 mL of sterile normal saline. Subsequently, the fluid is suctioned into a trap with a pressure below 100 mmHg adjusted to avoid visible airway collapse. In a healthy nonsmoking subject, the BAL cellular composition is macrophages (80–90%), lymphocytes (5–15%) with CD4/CD8 ratio of 1.5:1.8, neutrophils (1–3%), and eosinophils and mast cells <1% [37].Cell counts on BAL can have nonspecific results in many conditions such as cryptogenic organizing pneumonia and usual interstitial pneumonia, making its utility, to some extent, controversial [38, 39]. On the other hand, BAL plays an important role in the diagnosis of pulmonary infections, especially in immunocompromised hosts and mycobacterial infections, as well as in eosinophilic pneumonia [40, 41]. Higher yield can be achieved by adding TBLB [42]. It is important to mention that the presence of more than 5% squamous or epithelial cells represents contamination of the sample with bronchial secretions, rendering it a nonrepresentative sample of alveolar cells [36].
- 2.
Transbronchial Lung Biopsy (TBLB)
TBLB refers to sampling the lung parenchyma via flexible biopsy forceps. Anderson and colleagues first describe the method and results in 1960s and early 1970s [43, 44] (Fig. 2.7).
It is usually performed by first, wedging the bronchoscope in the bronchus. The forceps are then advanced in the closed position through the working channel of the bronchoscope, reaching the lung parenchyma where resistance is felt. The forceps are pulled back about 1 cm to open, readvanced until the desired tissue is in contact with the forceps, and closed again to obtain a biopsy.
The wedging position of the bronchoscope will facilitate further biopsies without the need to reposition the scope. It will also help isolate and tamponade any significant bleeding from the biopsy site.
The yield of TBLB increases with the number of biopsies taken. Descombes and colleagues showed that TBLB yield is increased from 38 to 69% when six or more biopsies are performed [45]. The yield is also dependent on the pulmonary disease being investigated. The yield in usual interstitial pneumonitis (UIP) is only 30%, whereas higher yield of 70% or more is seen in pulmonary diseases with:
Fig. 2.7
Biopsy forceps used with the flexible bronchoscope
TBLB has a low complication rate with major bleeding (greater than 50 mL) averaging 1% and risk of pneumothorax between 1 and 4% [2, 49, 50].
- 3.
Transbronchial Needle Aspiration
TBNA refers to sampling through the tracheal or bronchial wall. The mediastinal and hilar lymph nodes and lung and mediastinal masses can be sampled via this method. A thorough review of the patient’s chest CT and knowledge of thoracic anatomy is essential prior to proceeding. A retractable hollow cytology needle (21 or 22 gauge) or histology needle (19 gauge) is used, with suction applied to the proximal end of the needle. Fluoroscopy should be used when performing TBNA of peripheral lung lesions.
Wang and colleagues in 1978 performed the first successful TBNA of a paratracheal tumor via the flexible bronchoscope. They later published their experience with TBNA for hilar and mediastinal adenopathy [51, 52].
Blind TBNA is the term used for standard TBNA with no EBUS guidance. The sensitivity of blind TBNA varies according to size, location, number of aspirates per lymph node’s station, and the bronchoscopist experience. A sensitivity of 78% and specificity of 99% have been reported for blind TBNA in patients with lung cancer [53, 54]. Baaklini and coworkers found a yield of 64% for pulmonary lesions located in the inner third of the lungs vs. 35% for lesions located in the outer two thirds of the lungs. They also showed a lower yield for smaller lesions (<2 cm) [55].
Blind TBNA also has a role in the diagnosis of peripheral lung mass and nodules as Katis and colleagues first showed in 1995 [56].
Despite its great diagnostic utility, both ACCP and UK surveys have shown low routine use of blind TBNA in malignant and nonmalignant diseases with 11.8% and 2.3%, respectively, in the ACCP survey [15] and 10% use in the UK survey [2].
The overall complication rate for blind TBNA is quite low 0.8% [54]. The most common is damage to the bronchoscope working channel [15].
The introduction of EBUS-TBNA for mediastinal and hilar adenopathy and central tumors has replaced blind TBNA to a great extent. More guidance tools to reach peripheral lung nodules, like radial probe EBUS and virtual bronchoscopy have changed the way pulmonologists perform TBNA.
A brief review of advanced diagnostic bronchoscopy is to follow.
- 4.
Bronchial Brushings
Bronchial brushings involves the introduction of a small-protected brush via the flexible bronchoscope to the visible endoluminal lesion or peripheral pulmonary nodule with assistance via fluoroscopy or guidance tools of bronchoscopy (radial EBUS or virtual bronchoscopy techniques).
It is a useful tool to obtain both microbiological and cytological samples.
Protected brushings have shown to increase the diagnostic yield in peripheral lung nodules [57].
A review of 30 studies published in 2003 assessed the performance characteristics of different modalities for suspected lung cancer. They found that the diagnostic yield of all modalities combined for central endobronchial disease is 88%. The highest sensitivity is for endobronchial biopsy 74%, followed by cytobrushing 59% and washings 48%. For peripheral lung lesions, cytobrushing demonstrated the highest sensitivity (52%) followed by transbronchial biopsy (46%) and BAL/washings (43%). The overall sensitivity for all modalities was 69%. Peripheral lesions <2 cm or >2 cm in diameter showed sensitivities of 33% and 62%, respectively [58].
Advanced Diagnostic Bronchoscopy
- 1.
EBUS-TBNA
EBUS-TBNA refers to the technique of obtaining needle aspiration biopsies under direct sonographic visualization using the EBUS bronchoscope (Fig. 2.8).
The special flexible bronchoscope incorporates an ultrasound transducer at its distal end allowing real-time visualization and characterization of mediastinal and parabronchial structures and real-time needle aspiration of lymph nodes and lesions. The procedure is usually performed under moderate sedation. No advantage has been demonstrated by performing EBUS-TBNA under general anesthesia [59]. The reported safety profile is excellent. In their meta-analysis, Gu et al. reported only two complications in 1299 patients (0.15%) [60].
The current available needle sizes for EBUS-TBNA are 22G, 21G, and most recently 19G needle.
Nakajima and colleagues demonstrated no differences in the diagnostic yield between the 21G and 22G needles during EBUS-TBNA, though more blood contamination was present in the 21G needle TBNA biopsies. The preserved histological structure of the samples obtained by the 21G needle may be useful for the diagnosis of mediastinal and hilar adenopathy of unknown etiology which may be a challenge with the 22G needle [61].
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