Overview of Bronchoscopy and Its Employment in Pulmonary Emphysema

Abstract

Bronchoscopy is a medical procedure usually performed by a specialist for diagnostic or therapeutic purposes in the airway passages. There are two main types of procedure: rigid and flexible bronchoscopy, in addition to developed types such as ultrasound and navigational bronchoscopy to help improve the required outcome. There are several indications for bronchoscopy, but the leading one is suspicion of lung cancer, followed by detection of possible pulmonary infection. On the other hand, hypoxia is the main contraindication for his operation. A precise clinical history of the patient should be taken and multiple tests should be provided before the procedure. Sampling can be done in different ways depending on the indication. Overall, bronchoscopy is a minimum invasive procedure and complications are uncommon, especially for highly experienced doctors. However, patients with chronic pulmonary disorders such as COPD patients must be handled cautiously, especially when treated under sedation and those who have exacerbations.

1. Introduction

Bronchoscopy is the procedure of passing a camera or telescope into the trachea reaching the lower respiratory tracts to examine the large and medium-sized airways. It may be performed either in the way preferred by physicians where the patient is under local anesthetic with or without sedation using a flexible scope or as surgeons usually do, under general anesthesia with a rigid scope [1].

Bronchoscopy procedure has become a major tool for the pulmonologist, in addition to its diagnostic applications from airway inspection to sampling, it has also been used for its therapeutic capabilities such as palliative treatment of endobronchial tumors, also in the treatment of asthma and emphysema [2].

2. Types of bronchoscopy

There are two main types of bronchoscopy procedure: Rigid bronchoscopy and flexible bronchoscopy.

2.1 Rigid bronchoscope

A rigid bronchoscope is a stainless steel, straight cylindrical tube with an external diameter of 9–14 mm (Adult scopes are usually 7–9 mm and pediatric scopes are 3.5–6 mm). The length of the bronchoscope can be up to 45 cm and the thickness of walls is 2–3 mm. The tube is hollowed to allow the passage of different tools. The proximal third of some rigid bronchoscopes can have several ports for lung ventilation when inserted into the main stem bronchus (Figure 1) [4, 5].

Figure 1.

The three most common sizes of bronchial tubes are used in adults: (outer diameter/inner diameter mm color) A. 10/9.2 mm red, B. 12/11 mm (black), and C. 13.2/12.2 mm (orange) [3].

Visualization via a rigid bronchoscope can be done directly through the hollowed tube of the scope which is limited and unsuitable for fine details, or can be done by using a rigid optic telescope or video scope that is passed through the scope which is more convenient [6].

2.2 Flexible bronchoscope

A flexible bronchoscope is basically a thin flexible tube with a diameter range of 2.2–6.3 mm, containing fiberoptic bundles that carry light to the distal end inside the airways and transmit the image to an eyepiece or a monitor chip (video bronchoscope) which are more suitable for teaching and observation by multiple physicians. The flexible bronchoscope is also equipped with channels to insert different tools (brush, biopsy forceps, transbronchial aspiration needles, etc.) (Figure 2). An important advantage of this bronchoscope is the rotation of the distal end 180–180 degrees via a lever at the handle end of the scope in addition to manual wrist rotation which facilitates airway examination [2].

Figure 2.

A. Video flexible bronchoscope with connections to image processor and light source. B. Distal end of a video bronchoscope showing the instrument channel, fiberoptic, and charge-coupled device video chip that connects to the monitor for image processing [2].

There are three main sizes of flexible bronchoscope [6]:

• Pediatric (Ultrathin) bronchoscope with an outer diameter of 2.8 mm and a channel width of 1.2 mm. This small size allows suctioning and passing small tools such as brush for cytology tests and biopsy forceps. Nevertheless, clear visualization is limited to small sizes.

• Adult (Standard) bronchoscope has an outer diameter of 4.9–5.5 mm and a channel size of 2 mm, which allows baskets and greater suctioning.

• Therapeutic bronchoscopes of an external diameter of 6–6.2 mm and a larger channel size of 2.8–3.2 mm. This size is used for laser therapy and insertion of electrocautery instruments.

Over the recent decades, two new bronchoscopy techniques have been developed to help biopsy mediastinal and peripheral pulmonary lesions and examine beyond the airways.

2.2.1 Endobronchial ultrasound (EBUS)

The flexible bronchoscope in this type of bronchoscopy, the probe is combined with an ultrasound probe at the distal end of the scope, which allows the examiner to view more extended bronchial structures, lymph nodes, masses, and mediastinal structures. There are two types of the EBUS scope:

• Radial probe: This scope was developed first for early evaluation and detection of infiltrated cancer in the airway tissue, as well as an examination of peripheral and mediastinal lymph nodes [7, 8, 9]. The radial probe can be in two forms [10]:

  • The miniature: The probe is equipped with a balloon-tipped catheter that inflates with saline to obtain clear visualization by optimizing contact between airway walls and probe (Figure 3).

  • The ultra-miniature: In this type the inserted probe is covered with a guiding sheath, the lesion is examined and the image is obtained. Then the probe is removed with the sheath remaining in the spot and a biopsy forceps or a brush is passed to the sheath location for sampling (Figure 4).

• Convex probe: This scope allows direct visualization during biopsy sampling. The scope is equipped with a convex transducer at the tip that scans parallelly to the insertion direction of the bronchoscope (Figure 4). A saline inflatable balloon is also combined for a clear image and a fine aspirating needle covered with a removable sheath is inserted through the working channel to the lesion site for sampling during visualization [10, 11].

Figure 3.

A: miniature radial probe, B: balloon tip catheter, and C: the balloon tip inflated with saline [10].

Figure 4.

A: miniature radial probe, B: the balloon tip inflated with saline and a fine needle is inserted for transbronchial aspiration [10].

2.2.2 Electromagnetic navigational bronchoscopy (ENB)

This technology was first commercially available in 2006, where bronchoscopy is combined and compassed with CT imaging, which allows biopsy of lesions that can be difficult to reach [12]. It is usually performed in two stages: the planning stage and the procedure stage.

In the planning stage, the patient goes through a thin slice CT scan, which is then uploaded to the computer software that provides a three-dimensional image of the bronchial tree with more than one highlighted pathway created to the lesion for better biopsy outcome.

For the procedure stage, the patient is laid on an electromagnetic mat under their chest which is registered with both; the therapeutic bronchoscope and the three-dimensional airway construction with the highlighted pathways [13].

The disadvantage of this technology compared to the traditional CT-guided biopsy is the additional exposure to radiation for the planning stage and the cost of the dedicated software. However, with very minimum complications [14].

3. Indications for bronchoscopy

The major indications for bronchoscopy are suspicion of lung cancer followed by suspicion of pulmonary infection for microbiological sampling [2]. Table 1 lists the main indications for bronchoscopy, including diagnostic and therapeutic purposes.

Diagnostic indications	Investigation of symptoms like persistent cough, hemoptysis, and recurrent infection.
	Suspected lung cancer: Patients who have one or more of these signs: unexplained paralysis of vocal cords, stridor, localized monophonic wheeze, unexplained paralysis of hemi-diaphragm or raised right hemi-diaphragm and unexplained pleural effusions.
	Assessment of nodules or masses identified on radiology.
	Staging of lung cancer
	Suspected pulmonary infection: Assessment of pulmonary infiltrates, identification of organisms.
	Differential cell counts and cytology
	Transbronchial lung biopsy
Therapeutic indications	Foreign body removal
	Clearance of airway secretions
	Recurring mucus obstruction that causes lobar collapse and lung atelectasis in patients on ventilators.
	Emphysema (endobronchial lung volume reduction)
	Bronchial thermoplasty for asthma
	Endobronchial ablation of tumor (cryotherapy, electrocautery, laser).
	Insertion of airway stents.

Table 1.

Indications for bronchoscopy [1, 2].

4. Contraindications of bronchoscopy

• The main contraindication for bronchoscopy is hypoxia which cannot be adequately corrected by oxygen supplementation. Therefore, if the patient’s air saturation is less than 90% at rest or less than 8 kPa, the risk of hypoxia is greatly increased during the procedure [1, 2].

• If the forced expiratory volume (FEV1) was below 40% [1].

• Bleeding tendency: Blood clotting abnormalities, especially platelet level <50,000/mm3 [1].

• Pulmonary hypertension (PHT), uremia, superior vena cava obstruction (SVCO), liver disease, and immunosuppression [1].

• Recent myocardial infarction (MI) may be associated with cardiac ischemia during bronchoscopy [1].

• Cervical spine instability [3].

• Failure of the patient or his representative (in special cases) to provide consent for the operation [2].

However, even in these circumstances, similar to other invasive procedures, firm cut-offs are not given as the risks and benefits of bronchoscopy should be carefully evaluated on an individual patient basis [2, 3].

5. Patient preparation and procedure

5.1 Patient preparation

5.1.1 Information

Informed consent should be obtained from the patient or the patient’s health care power of attorney, ideally >24 h prior to the procedure [1, 15]. The patient should be provided with written information in advance of the procedure and the key aspects, such as the risks of the procedure and the effects of any sedation and possible complications. Also, alternative approaches should be discussed before final consent [1, 2].

5.1.2 Clinical history

• A focused history and physical examination should be obtained to ensure the procedure is clinically indicated. The patients should fast (nothing by mouth) for six to eight hours before the procedure, but they may be allowed to drink water for up to 2 hours before the procedure [2, 15].

• Patients should have a full blood count and clotting prior to transbronchial lung biopsy and interventional procedures, such as tumor ablation [2].

• It is safe to stop anticoagulation if a patient is taking aspirin or prophylactic low-molecular-weight-heparin LMWh. On the other hand, patient should stop clopidogrel seven days before the procedure (may require cardiology consultation), also the patient should wait until INr is below 1.5 if he is on warfarin, in high-risk conditions, for example, mitral prosthetic metal valve, prosthetic valve or thrombophilia syndromes the patient may need a full-dose of LMWh on days before bronchoscopy [1].

• Besides tests, an ECG may be performed in patients with a history of cardiac disease. Blood sugar should be checked in patients with diabetes [1].

• Before starting the procedure, oxygen saturation level should be monitored using pulse oximetry, also intravenous access should be assured. The patient’s medication list, any possible allergies, and all laboratory results should be checked [15].

• Pulse oximetry should be monitored during the procedure and venous access should be present in all patients [1].

• Spirometry should be used if oxygen saturation is below 95% [2].

• Arterial blood gas test should be done if oxygen saturation is below 92% [2].

5.1.3 Sedation

Most bronchoscopy procedures are performed under moderate conscious sedation even though the procedure may be performed without sedation. The sedatives used are usually chosen based on the clinician’s preference (e.g., benzodiazepines, opioids, and dexmedetomidine). There are some cases where procedures may require more deep sedation or general anesthesia. In general, physicians should be aware of the potential side effects and how to manage patients receiving these medications regardless of the sedation or anesthesia used. If patients are to have any sedation, it is highly important that someone is going to accompany them home after the procedure [2].

• Nebulized bronchodilators are considered if there is evidence of bronchospasm in patients with asthma [1, 2].

• Prophylactic antibiotics are considered if there is a very high risk of endocarditis: asplenia, heart valve prosthesis, or previous history of endocarditis [2].

5.1.4 Procedure

The procedure can be performed with the patient sitting upright in a semi-recumbent position and being approached from the front (Figure 5A). This has the advantage of allowing it to be carried out in sicker patients who are desaturated upon lying flat [2].

Figure 5.

Patient positioning during bronchoscopy procedure: A: The semi-recumbent position, B: The posterior position.

The posterior approach with the patient lying flat is also widely used (Figure 5B). This approach is also required in several procedures such as endobronchial ultrasound and the super dimension procedure [2].

The nasal route is the most accessible way to the trachea where the bronchoscope is introduced into the nasal cavity, as this route gives more stability when taking biopsies and it permits the patient to cough and spit out secretions more easily. When the nasal way is not possible, a mouth guard is used and advanced to the level of the vocal cords [1, 15].

During the procedure, the movement and the appearance of the vocal cords are assessed. Later, while the bronchoscope advances beyond the vocal cords, a careful inspection of the entire airway is performed. Assessment of any abnormal endobronchial lesions or mucosal abnormalities, as well as any evidence of narrowing or dynamic collapse, is done particularly [15].

All sections of the bronchial tree should be visually checked, including the cords and trachea. Also, to increase the diagnostic yield of bronchoscopy in lung cancer suspected cases, a chest X-ray or CT may help to localize the area of concern, so the biopsy site can then be targeted accurately [1].

It is preferable to record photos and videos so they can be used as references when it is needed. Any unnecessary contact with the mucosa should be avoided to stay away from any available trauma, also unnecessary suction should be avoided, as this can increase hypoxia [1, 15].

The appropriate tools for the procedure are chosen according to the required indication and the task to be performed during bronchoscopy, such as tumor debulking or taking a tissue biopsy. At the end of the procedure, a final evaluation of the airway should be performed to ensure adequate hemostasis. The patient may need a chest X-ray after the procedure to evaluate the presence of a pneumothorax. All patients should be monitored before, during, and after bronchoscopy. The patient may be discharged on the same day after ensuring recovery and the absence of any complications, also an appointment is scheduled to follow up on the case. Since the effect of medications may last for several hours, the patient is advised not to drive, operate heavy machinery, or participate in any activity that requires full consciousness for the rest of the day [15].

6. Sampling in bronchoscopy

Different sampling techniques can be performed based on indication and the required test [2]:

• Bronchial washings (BW): This technique allows targeted sampling of proximal or segmental airways. The bronchoscope is held proximal and close to the location of abnormality. An aliquot of 10–20 mL saline is instilled and aspirated back. The sensitivity of bronchial washings is very variable (average 50%; range 21–76%).

• Endobronchial biopsy (EBB): In this technique, forceps are inserted through the instrument channel of the bronchoscope. The forceps are just opened, at the location of the lesion and then closed in order to obtain biopsies under direct vision (Figure 6). Multiple biopsies are recommended for more accurate results.

• Bronchial brushings (BB): This sample can be obtained by using the cytology brush to scrape some cells from the surface of the lesion or the examined area. The brush consists of fine bristles with a protective plastic sheath. The instrument is passed through the instrument channel of the bronchoscope toward the abnormal area. The sheath is then removed and the brush is rubbed against the abnormal mucosa. The brush is then withdrawn back into the plastic sheath (Figure 7).

• Bronchoalveolar lavage (BAL): The technique is performed by wedging the bronchoscope on the desired subsegment. With the bronchoscope in position, saline aliquots of 50 ml are repeatedly instilled and aspirated either manually or using a low-pressure suction, reaching a total of 250 ml based on the desired testing or indication.

• Transbronchial biopsy (TBB): This technique is performed to evaluate the assessment of diffuse lung disease and in patients where there is a localized parenchymal shadow. The biopsy forceps are inserted into the desired segment through the instrument channel of the bronchoscope. The insertion of the forceps proceeds until resistance is felt during inspiration. The forceps are then withdrawn 1–2 cm and opened. At this point, the patient should breathe out whilst the forceps are moved further during expiration. When resistance is felt, the forceps are closed and gently pulled. It is recommended to obtain multiple biopsies for better outcome.

Figure 6.

Distal view of the biopsy forceps in an open and closed position [2].

Figure 7.

Close-up of a bronchial brush (left) and handle (right): when the brush is pulled out of the sheath [2].

7. Complications of bronchoscopy

7.1 Complications of flexible bronchoscopy

Flexible bronchoscopy is a safe operation with a low rate of complications. Reported mortality rates in large series are 0.01–0.04% and major complications of 0.08–1.1% [1]. In a recent study performed on 3,473 patients had done FB. Complications occurred in 5.3% of patients were as follows: 2.2% suffered from moderate to severe bleeding, 0.7% had pneumothorax, and 0.8% suffered from severe bronchospasm. Generally, complications like (hypoxemia, psychomotor agitation, arrhythmias, vomiting, or hypotension), were shown in 1.6% of patients; and cardiopulmonary arrest occurred in 0.03% of them. No deaths related to the procedures were recorded [16].

In general, complications of flexible bronchoscopy consist of respiratory depression, pneumonia, pneumothorax, airway obstruction, laryngospasm, cardiopulmonary arrest, arrhythmias, pulmonary edema, vasovagal episodes, fever (especially following BAL), septicemia, hemorrhage, nausea, and vomiting [1].

Although most complications are caused by sedation and topical anesthesia [17]. However, several factors also play a role in causing complications, including the patient’s clinical condition, the insertion of the bronchoscope into the airway, in addition to the techniques used in taking biopsies such as BAL, EBB, TBB, and BB [18, 19]. Usually, most complications occur within 2 h after the procedure, and only a minority of patients require hospitalization [17, 20, 21, 22]. In general, side effects such as tension pneumothorax, heart/respiratory failure, and death are rare but they are serious and require interrupting the operation. The previous side effects are often related to the severity of underlying heart or lung disease, as well as to severe central airway obstruction [21, 23, 24].

To ensure the lowest rate of complications, standardized care protocols are developed, in addition to continuing suitable training of specialist doctors and nursing staff [16].

Moderate-to-severe bleeding occurs in 70.7% of patients, as a result of mechanical trauma from the bronchoscope, suctioning, brushing, or sampling, but is more common with transbronchial lung biopsy (TBB) (1.6–4.4%). The patient clinical status also plays a role, as patients suffering from malignancy, immunocompromise, or uremia are more susceptible to bleeding [1].

In cases where severe hemorrhage occurs, the patient should be turned onto the side of the bleeding to protect the other lung. The bleeding area may be tamponade using a balloon-tipped vascular catheter. If bleeding continues, emergency interventional radiology or thoracic surgery may be recommended [1].

7.2 Complications of rigid bronchoscopy

Similar to flexible bronchoscopy, when rigid bronchoscopy is performed by well-trained doctors, complications are uncommon [25]. The most common complaint following rigid bronchoscopy is a sore throat, which usually subsides 24–48 hours after the procedure. As for serious complications, they are uncommon (<2%) and their causes are limited to either anesthesia or the operation itself [26, 27].

Several studies confirmed the rarity of complications, one of which took place in a tertiary-care university hospital, the study included 775 rigid bronchoscopies, the overall complication rate was 13.4%, most of the complications were mild, and severe complications were rare with a 0.4% mortality rate [28, 29, 30]. Another large series included 11,000 rigid bronchoscopies, and only 2 deaths were recorded [31, 32]. As for therapeutic applications, a recent study of the AQuIRE registry found the overall complication rate of therapeutic bronchoscopy done with rigid bronchoscopy to be 3.4% [32, 33].

Injury to the oropharyngeal structures, laryngeal edema, spinal cord injury, injury to vocal cords and arytenoids, airway laceration and perforation, and hypoxemia-induced cardiac ischemia and arrhythmias [3] are serious complications of rigid bronchoscopy that could be avoided with proper preoperative assessment, appropriate instrument preparation and maintain adequate communication with the anesthesiologist [28].

8. Bronchoscopy safety in patients with chronic obstructive pulmonary disease (COPD)

Although bronchoscopy is considered as a minimum invasive procedure, the British Thoracic Society has listed patients with COPD who need diagnostic bronchoscopy as a needing caution. A study by Grendelmeieret al. reported no difference in bronchoscopy complications between COPD and non-COPD patients [34]. On the other hand, a study conducted by Bellinger et al., to compare complications rate between patients with or without COPD going through bronchoscopy procedure under moderate sedation; concluded that bronchoscopy is generally tolerable with few complications in patients with COPD. However, those with confirmed severe/very severe COPD are at higher risk of complications than those without COPD [35]. Also, a systematic review and meta-analysis on the topic reported that the major complications rate in bronchoscopy are higher in COPD patients with exacerbations than those who are stable [36].

9. Bronchoscopic management of emphysema

Recently, several bronchoscopy techniques have been used for intervention in chronic pulmonary diseases such as emphysema. The main objective of such procedures is to deflate the volume of the lung or the targeted lobe, which can be done with one of the following techniques [37]:

• Endobronchial valves:

Valves in those techniques are essentially one-way valves that are introduced into a segmental targeted lobe via bronchoscopy with a flexible catheter under local or general anesthesia. Those valves facilitate the expiration of trapped air in the targeted lobe and prevent air inspiration, therefore preventing lobar or lung collapse. Recent RCTs concluded that misplacement of valves or patients on collateral ventilation do not come with promising results. Therefore, endobronchial valves are recommended in either heterogenous or homogenous emphysema patients without collateral ventilation, with the assessment of CT scan along with using the Chartis system for endobronchial measuring [37, 38, 39].

• Endobronchial coils:

Endobronchial coils are nickel-titanium shape-memory coils that are introduced into subsegmental bronchi in a targeted lobe via bronchoscopy with an insertion catheter. These coils retract the parenchyma, decrease lung volume, and facilitate lung rebound. The procedure is performed with fluoroscopy guidance under general anesthesia. About 10–12 coils are placed in the upper lobes and up to 14 in the lower lobe. Usually, treatment of the other side must be performed after 1–3 months from the first side treatment. Unlike endobronchial valves and according to recent studies, this technique is recommended for heterogeneous or homogenous emphysema patients with or without collateral ventilation. However, this technique cannot be performed when the lungs are over-destroyed because viable parenchyma is required for enhanced performance [37, 39, 40, 41].

• Bronchial thermal vapor ablation:

In this technique, a hot water steam is delivered through a bronchoscopic catheter to a targeted area of the lung, which causes parenchymal tissue fibrosis due to inflammation caused by heat and eventually lung volume reduction. This procedure is performed for heterogeneous emphysema patients with or without collateral ventilation [37, 39, 42].