Photo courtesy of National Cancer Institute

Bronchoscopic history began in 1890 when the first laryngeal intubation was done accidentally during an esophagoscopy.1 The technique of performing laryngeal intubation and advancing the scope into the lobar level followed shortly thereafter. In 1897, Gustav Killian removed a piece of pork bone from the right main bronchus using an esophagoscope.2 Physicians had been inserting endoscopes into other body cavities for several years, but this particular episode represented a tipping point for further medical inspection of the human airway. Through the late 1890s, a number of physicians began using endoscopy with what were basically rigid bronchoscopes. Clearly, technical improvements to endoscopes have followed, but bronchoscopy using a rigid scope remains a useful component in the diagnosis and treatment of patients with pulmonary disease.

Rigid bronchoscopy (RB) is most useful when there is a need to view the trachea and proximal airways and is most frequently performed under general anesthesia. As the term implies, the scope used for this procedure is a straight hollow tube and is frequently the same diameter from one end to the other. Compared to other scopes, its internal and external diameters are relatively large, which makes it ideal for many applications, such as:

  • removal of copious amounts of viscous secretions
  • aiding in tonsillectomies
  • removal of foreign objects
  • laser surgery
  • stent placement

These scopes come in a variety of sizes (2 mm to 14 mm) and can view large airways from fixed angles of 0, 30, 40, 50, 90, and 180 degrees. Some scopes have a beveled tip, which facilitates lifting of the epiglottis. Others have tip variations to allow dilation of bronchial strictures. Rigid scopes also can be used to analyze expired gases. They may even incorporate the use of laser fibers for tumor shrinkage. Rigid scopes of varying lengths may be used to provide ventilation to one lung while working within the main bronchus. The light source is usually xenon or halogen bulb. The newer scopes have an iris similar to the human eye, which can adjust the amount of light being applied and minimizes glare on the mucosa. Most rigid scopes have the ability to add video components, which enhances their value as a teaching tool. Ironically, the features that make it the ideal tool for some conditions also limit it in other applications. Specifically, its large diameter and rigid bias limit its application when a study involving peripheral lung fields is required.

Flexible Bronchoscopy

Flexible bronchoscopy (FB) was developed in the 1960s and is the technique used most often for bronchoscopy today. The flexible scope allows visualization down to the segmental bronchi (third generation). Flexible bronchoscopy is a useful tool in both therapeutic and diagnostic circumstances involving infant or adult patients. The list of applications is extensive and includes:

  • clearing of copious secretions
  • instillation of cold saline for control of hemoptysis
  • administration of topical vasoconstriction agents
  • staging of tumors
  • laser therapy (including laser-assisted resection)
  • aid in the placement of airway stents
  • brachytherapy
  • electrocautery
  • cryodebridement

The outer diameter of the flexible bronchoscopes varies depending on the patient’s size (Table 1).

Knowing the outer diameter of the scope is key to selecting the proper sized scope for patients with artificial airways (3.9 mm to 9.0 mm). The scope should not take up more than 60% of the inner diameter of the artificial airway. Flexible bronchoscopy can be performed using local anesthesia and conscious sedation or with general anesthesia. It allows for greater flexibility and distal visualization than rigid bronchoscopy and is most helpful in cases where it is difficult to identify a pathogen in patients with pneumonia or other pulmonary disease processes. Flexible bronchoscopy also plays a role when other forms of therapy are provided, including laser therapy, balloon dilatation, stent placement, cryotherapy, argon beam coagulation, and electrocautery.

Equipment used with FB are aerobic and anaerobic brushes; various biopsy forceps, eg, round jaw, radial jaw, and round cup with needle; aspiration needles; foreign object retrieval baskets; snares; and three-prong graspers. Other tools are available in order to facilitate stent placement or to provide brachytherapy, cryodebridement, or electrocautery.

Contraindications to bronchoscopy include bronchospasm, hypoxemia, laryngeal spasm, hemoptysis, pneumothorax, cardiac arrhythmias, infection, laryngeal edema, bacteremia, vasovagal syncope, seizure, methemoglobinemia, laryngeal injury, epistaxis, and transient hypotension.

Fiber-optic bronchoscopy continues to be frequently used by today’s pulmonologists. Recent advances in bronchoscopy technology, such as endobronchial ultrasound guided bronchoscopy and electromagnetic navigational diagnostic bronchoscopy, have enhanced the diagnostic value of this procedure.

Endobronchial Ultrasound Guided Bronchoscopy (EBUS)

Ultrasound studies use high-frequency sound waves to produce images of tissue and fluid for diagnostic imaging studies. EBUS combines ultrasound with FB and was first introduced in 1992 and brought to the United States in 2002. If a fiber-optic scope is inserted into a patient’s trachea, it can only display images of the inside of the airway. EBUS can provide much more. The ultrasound component allows EBUS to view tissue that surrounds the airway (vessels, lymph nodes). It can even distinguish specific tissue layers of the bronchial walls (adventitia, connective tissue perichondrium cartilage, endochondrium, submucosa, and mucosa) and any abnormalities that might be located within them. Diseased or infected lung tissue, enlarged lymph nodes, and neoplasms outside the airway or in the mediastinum can all be visualized and biopsied using EBUS. It may be more accurate than invasive methods when staging lung cancer and evaluating mediastinal anomalies, such as lymph adenopathy and other lesions. These abnormalities may not be visible with other diagnostic techniques such as fluoroscopy or even CT scan. Using this technique to locate and biopsy suspicious lesions may eliminate the need for more invasive types of sampling (open lung biopsy).

The EBUS bronchoscope has a diameter of 6 mm, which is similar to that found in a standard adult bronchoscope. The scope has a curvilinear probe at its distal end, which gives it a 50° linear continuous ultrasound image, combined with a color-flow Doppler to assist in identifying vascular structures. Proximal to the ultrasound probe at a 30° angle to the long axis of the scope are a fiber-optic lens and a biopsy channel through which a 22G biopsy needle can be threaded. A disposable latex balloon is placed over the ultrasound probe and is inflated with sterile water. This provides an interface between the probe and the tracheal wall. As the scope descends down the bronchial tree, it is positioned in a way that allows a view of the branches of the pulmonary artery. This minimizes the chances of an inadvertent vascular biopsy. Once the optimal position is attained, the physician can map all of the nodules that are going to be biopsied. This is an essential step in the process, because bleeding from needle sampling may obscure the bronchoscope’s view. The size of the nodules can be measured by freeze-framing the image using computer software to estimate their dimensions. From there, the needle is used to obtain samples. Patients undergoing EBUS may receive conscious sedation and topical anesthesia, or the procedure can be done under general anesthesia.

EBUS has many advantages and few disadvantages, and when the usual safety practices are followed, the frequency of procedure-related complications is low. Training on the use of EBUS is intensive and requires the ability to interpret ultrasound images, which are different from those normally seen on x-ray. It is recommended that those who complete EBUS training maintain their skills by performing at least 20 EBUS procedures per year.

Electromagnetic Navigational Diagnostic Bronchoscopy (ENDB)

ENDB is a tool used to biopsy lesions in the lungs that would be difficult or even impossible to reach using conventional techniques. There are many patients who demonstrate an abnormal finding on chest x-ray, but the lesion is so small and so far into the lung periphery that the risk of performing a surgical biopsy is significant. Biopsy using a fiber-optic scope could be an alternative, but locating the lesion is difficult—an estimated 65% of conventional bronchoscopies fail to reach these lesions. The problem is that a chest x-ray is a two-dimensional image, and the lung is a three-dimensional organ. Positioning the bronchoscope into the area where the lesion is located requires knowing which anatomical route to take. In a case like this, ENDB could be very helpful.

The process begins with a CT scan. This helps to determine the lesion’s specific location. This information is then transferred to a navigational phase through proprietary software. On the day of the procedure, the patient lies on an electromagnetic board with electrodes similar to ECG leads positioned on the chest in a triangular arrangement.

Signals from these leads and the information from the CT scan act as a type of global positioning system. Instead of telling a driver which streets to turn on, this system will display a colored ribbon of light on a screen showing the physician which bronchus to follow. These systems are reported to have the ability to reach more than 17 generations of airways. A sensor probe is passed through the bronchoscope and shows the physician the position of the bronchoscope and its proximity to the target. When the tip of the scope is within approximately 1 cm of the lesion, the outer catheter is locked and the guide sensor is removed. At this point, various brushes and biopsy devices can be passed through the working channel and samples can be obtained. These are immediately given to a pathologist who can confirm the type of any abnormal cells, and many times a diagnosis can be made during the procedure. If indicated, therapy can be started without delay, which can have life-saving implications for the patient. As with any bronchoscopic procedure, there are inherent risks but ENDB minimizes the need for more traditional invasive surgical maneuvers and longer hospital stays.

Conclusion

From an accidental procedure in 1890 to ENDB today, bronchoscopic technology has advanced to encompass numerous diagnostic and therapeutic modalities.


Patricia Dugger, CRTT, CPFT, is a respiratory therapist at Long Beach Memorial Medical Center, Long Beach, Calif. She works in the ED, ICU, CCU, and PICU. She is also the clinical work instructor for respiratory therapy students. For further information, contact [email protected]

References

  1. Becker HD, Marsh BR. History of the rigid bronchoscope. In: Bolliger CT, Mathur PN, eds. Interventional Bronchoscopy, Progress in Respiratory Research. Volume 30. Basel, Switzerland: Karger; 2000:2–15.
  2. Kollofrath O. [Removal of a bone fragment from the right bronchus in a natural way and through use of direct laryngoscopy.] Münchener Medizinische Wochenschrift. 1897;38:1038–9.