TSRA Content:
Author: Brock Daughtry, DO
This is a revision and update from the previous edition of the TSRA Primer in Cardiothoracic Surgery written by Jacob Klapper, MD, Siva Raja, MD, Neil Ninan, MD, Scott Shofer, MD
Flexible bronchoscopy
Flexible bronchoscopy is performed for a wide variety of indications. They include but are not limited to severe or changing cough, abnormal chest radiograph, unresolving pneumonia, smoke inhalation, tissue sampling or biopsy, and bronchoalveolar lavage. One may also choose to perform flexible bronchoscopy in the setting of atelectasis, lung abscesses, difficult intubations, aspirations, obstructive atelectasis, or management of hemoptysis.
Flexible bronchoscopes come in a variety of sizes, ranging from outer diameters of 2.4-6.2 mm. The smaller bronchoscopes are used more commonly for pediatric patients and those who will not tolerate larger scopes. The disadvantages of these smaller scopes are smaller working channels and decreased suction capacity. Conversely, larger bronchoscopes have better suction ability and larger working channels but can be more irritating. Larger bronchoscopes also have a larger field of view, usually measuring 120 degrees compared to 40 degrees for the smallest scopes. All bronchoscopes have a standard of 180 degrees of deflection in the superior direction and 130 degrees in the inferior direction.
Bronchoscopes can also be classified as standard flexible bronchoscopes or video fiberoptic bronchoscopes. Video bronchoscopes require a separate tower, but offer a larger, higher resolution image than a standard scope. Their outer diameters range from 3.8 to 6.2 mm. Their instrument channels vary only slightly in diameter. Their degrees of deflection and field of view are no different.
Routine bronchoscopy can be performed on both the awake and sedated patient, as well as those who are under general anesthesia or intubated in the intensive care unit. When performed on an awake patient, the patient must have an adequate pulmonary reserve and the ability to tolerate the somewhat noxious stimuli of the procedure. Patients who can cooperate with the exam are more likely to do well. It may also be beneficial to discuss a deviated septum, previous sinus surgery, or a preferred nostril with the patient before proceeding, as this may make for a more tolerable procedure.
Procedural Technique:
The standard monitoring for conscious sedation is also used to monitor the patient throughout the procedure. This includes pulse oximetry, blood pressure, and electrocardiogram monitoring. The choice of sedation, and whether sedation is indicated at all, is a conversation to be had between the anesthetist and the bronchoscopist and is largely patient-dependent. According to Harzheim, published in General Thoracic Surgery in 2019, several studies indicate that over 50% of life-threatening complications arise from hypoxemia, hypercapnia, and respiratory depression due to oversedation. For this reason, planning and constant communication between the anesthetist and the bronchoscopist are key.
Local anesthesia can also provide increased comfort for the awake patient and increased success for the practitioner. Local anesthesia options start at the nares, where lidocaine jelly can be of great benefit. Viscous lidocaine can be used as a lubricant on the end of the scope. Aerosolized lidocaine is usually sprayed in the posterior oropharynx, sometimes using a 4x4 gauze to depress the tongue. The patient should then be encouraged to swallow for greater coverage. Make sure the scope, light, and suction are all working appropriately. Ensure all instruments and sterile saline or medications that may be used are readily available.
Before starting the procedure, the patient should be placed on supplemental oxygen with 100% FiO2. For an awake patient, the scope is then passed through the previously selected nostril to the back of the tongue. During this maneuver, a gentle downward curve can be helpful. The vocal cords should come into view. If the patient can participate, have them pant, deep breathe, or say “Ahh” to assist with the abduction of the vocal cords for easier passage of the scope and less trauma to the tissues. It may also be beneficial to spray local anesthetic through the bronchoscope to numb the cords before advancing. Once through the cords, advance the bronchoscope until the carina is visible. A topical anesthetic can again be used on the carina to decrease discomfort and the threat of coughing. Orientation can be obtained by keeping in mind that the posterior trachea is membranous while the anterior trachea is made of cartilaginous rings, as these distinctions are usually visible and discernable. For an intubated patient or one under general anesthesia, the bronchoscope will be placed through the port of the endotracheal tube and advanced through the end of the endotracheal tube until the carina is visible. Orientation is obtained in a similar fashion as in the awake patient.
The right mainstem bronchus branches at a more acute angle than the left and is usually entered first. The right upper lobe stems from the lateral wall of the mainstem bronchus and branches fairly proximally. Withdrawing back to the right mainstem and progressing distally will reveal the bronchus intermedius. The right middle lobe bronchus arises medially/anteriorly while the superior segmental bronchus arises posteriorly, immediately distal to the right middle lobe bronchus. The segmental bronchi continue distally.
The left mainstem bronchus arises more obliquely and is usually longer and more linear than the right mainstem. It bifurcates into the left upper lobe bronchus (located anterolaterally) and the left lower lobe bronchus (located posteromedially). The left upper lobe bronchus divides into the upper and lingular divisions, which arise laterally and medially, respectively. Alternately, the superior segment of the left lower lobe is located proximally and posteriorly off the left lower lobe bronchus. The basilar segments continue distally.
Bronchoalveolar lavage (BAL) may be performed at any point after diagnostic imaging. BAL can be both diagnostic and therapeutic for treating mucous plugs, diagnosing pneumonia, diagnosing interstitial lung diseases, and isolating microorganisms, particularly in immunocompromised patients. It is best performed at the subsegmental bronchus level. The bronchoscopist irrigates with 30-50 mL of sterile saline into the lingula or middle lobes, preferably. These locations are preferred due to the greater volume of irrigation recovery. The fluid is suctioned into a trap and sent for appropriate analysis.
Following the termination of the procedure, the patient is weaned to pre-procedure oxygen requirements. A post-procedural chest X-ray is usually performed to rule out complications, such as pneumothorax.
Rigid bronchoscopy
Rigid bronchoscopy, once the only method for visually inspecting the airway, is now indicated for evaluation and management of bronchial lesions with definitive control of the airway. These specific purposes include foreign body retrieval, management of an obstructive lesion, biopsy of bronchial masses, management of significant hemoptysis, bronchial stent placement, and dilation of bronchial strictures. Another benefit of rigid bronchoscopy is the ability to maintain the airway after an obstructing lesion is removed, allowing an opportunity for definitive control.
Preoperative evaluation for rigid bronchoscopy is like that of other minor surgical procedures. Patients are almost always required to undergo general anesthesia so they should meet the standard requirements set forth by one’s institution for anesthesia. General laboratory evaluation, including complete blood count, complete metabolic panel, and coagulation profile, should be obtained. Patients should be asked to withhold any blood thinners due to the increased risk of bleeding with any biopsies performed.
Of special interest in rigid bronchoscopy is the evaluation of the patient’s neck mobility. A patient should have an excellent range of motion in all planes to facilitate navigation of the scope through the patient’s airway. This includes flexion and extension, but also the ability to tilt the head to either side until the ear rests on the ipsilateral shoulder. Any difficulties in the manipulation of the head should be addressed before beginning so the appropriate procedural planning can be made.
As with any procedure, risks and benefits, including those of general anesthesia, should be discussed with the patient. The general risks of bronchoscopy include bleeding, infection, respiratory failure, prolonged intubation, and pneumothorax. Rigid bronchoscopy does come with a rather specific set of complications including, but not limited to:
- Damage to the teeth, tongue, hard and soft palates, pharynx, larynx, and vocal cords
- Airway perforation
- Pneumomediastinum
- Hemorrhage secondary to injury to the great vessels
- Airway fire
Airway fire is a rare, but often fatal, complication of rigid bronchoscopy. Due to the use of several forms of thermal energy (lasers, radiofrequency ablation, electrocautery, argon plasma coagulation, etc.) used to treat hemoptysis, central airway obstruction, and to cauterize biopsy sites, the bronchoscopist and anesthesiologist should be working to avoid an airway fire at all times.
Ventilation
During rigid bronchoscopy, communication between the bronchoscopist and the anesthesiologist is essential. The bronchoscopist controls and maintains the airway while the anesthesiologist watches for signs of adequate oxygenation and ventilation. Standard end-tidal CO2 and pulse oximetry can be used to monitor a patient’s status. There are two main types of ventilation utilized in rigid bronchoscopy:
- Jet ventilation – This allows for the free introduction of instruments through an unobstructed system. Pressure is generated either by hand or by a pump. Enough pressure is instilled to create chest rise, at an appropriate FiO2. This is typically performed at a rate of 12-15 times per minute.
- Volume ventilation – A fenestrated cap is placed over the side port of a bronchoscope to create a more traditional closed-circuit ventilation.
Procedural Technique:
The patient is given general anesthesia and bag-mask ventilation is used to prepare the patient for the procedure. A bite block or tooth guard can be placed over the patient’s upper teeth. If using a telescope for magnified visualization during entry, insert it to the distal end of the bronchoscope, but ensure the entire beveled end is in view to reduce the risk of injury.
The rigid bronchoscope is then held in the operator’s dominant hand with the barrel between the thumb and index finger. The non-dominant hand is used to clear the patient’s tongue, and the thumb and middle finger are used to protect the patient’s dentition. The patient’s head should then be flexed to allow for a straighter alignment of the oropharyngeal axis.
The scope is advanced under direct visualization directly down the patient’s mouth to the base of the tongue, with the bevel up. The epiglottis should be visualized. The bevel of the bronchoscope is used to elevate the epiglottis, allowing the vocal cords to come into view. The bronchoscope should be advanced in a forward and upward motion. Similar to intubation, the vocal cords must be exposed by an anterior motion of the entire bronchoscope instead of a lever motion against the patient’s teeth to avoid damage to the teeth.
To pass through the vocal cords, the rigid bronchoscope is rotated 90 degrees so that the bevel is parallel to the vocal cords, and the bevel is passed gently through. As the end of the scope is advanced through the cords, the bronchoscope is rotated another 90 degrees so that the bevel is now resting against the posterior trachea, beveling down. It is crucial to keep constant elevation of the tip of the scope to prevent injury to the membranous surface of the posterior tracheal wall.
At this point, the bronchoscopist has gained control of the patient’s trachea. The telescope can now be removed from the rigid bronchoscope, allowing direct visualization of the trachea through the eyehole. This will also allow for the passage of instruments, suction catheters, and even flexible bronchoscopes into the patient’s airway. The scope can be carefully advanced under direct visualization to the level of the carina.
The scope can now be maneuvered into either mainstem bronchus. The side ports on the bronchoscope allow for ventilation of the contralateral lung. While advancing to, and inspecting past the carina, the patient’s head should be turned towards the contralateral side of the bronchus being interrogated. The entire distal end of the scope must be in full view to decrease the risk of injury.
Therapeutic Procedures
A myriad of instruments is available for use during rigid bronchoscopy, and these should be considered and made available before starting the procedure. Some instruments are passed directly through the bronchoscope while others are passed through a working channel. Some rigid bronchoscopes (Dumon-Harrell) allow for multiple instruments to be passed through the channel, including a telescope for improved visualization, without compromising ventilation. One may also choose to insert 45-degree or 90-degree side viewing telescopes through the working channel to evaluate portions of the bronchus that may not be visualized directly. Other instruments routinely used in rigid bronchoscopy include rigid/semi-rigid forceps, suction catheters, biopsy forceps, cryotherapy, microdebriders, biopsy needles and endobronchial stents. One may also choose to pass a flexible bronchoscope through the rigid bronchoscope and use the former’s working channel as well.
As mentioned earlier, a specific consideration while performing therapeutic procedures is the threat of airway fires. Any heat-based therapy, whether that be electrocautery, argon plasma, or laser therapy, comes with a significant risk of airway fire. Heat should be used at the lowest FiO2 possible with a maximum threshold of 40%.
Post Procedural Care
Following careful removal of the rigid bronchoscope from the patient’s airway, the airway, oxygenation, and ventilation may be maintained in whatever manner is deemed necessary. This includes mask ventilation, laryngeal mask airway, or endotracheal intubation depending on the clinical situation. A postoperative chest X-ray is performed following the completion of the procedure to rule out any complications, specifically pneumothorax or pneumomediastinum. Patients should be counseled on the likelihood of a sore throat/hoarse voice for 24 hours following rigid bronchoscopy. Depending on the procedures performed, residual blood may be expectorated following the procedure. The patient must understand that any substantial amount of hemoptysis, chest pain, or worsening shortness of breath should be evaluated immediately and may require intervention.
Endobronchial Ultrasound
Endobronchial ultrasound (EBUS), first developed in 1992, was once used mainly for confirmation of negative mediastinoscopy biopsies. However, as the technique has become more common, data have been reported that EBUS sampling is at the very least equivalent, and in some cases, superior to mediastinoscopy. EBUS allows the operator to visualize structures adjacent to the major and some minor airways and perform image-guided transbronchial needle aspiration of mediastinal and hilar lymph nodes and masses. EBUS plays a role in the diagnosis and staging of pulmonary malignancies, but also has a role in additional diagnoses, such as lymphoma and esophageal cancer.
There are two main types of EBUS scopes: radial and linear. Radial EBUS provides a circumferential view of the airway and lung parenchyma. It is performed by passing a miniature, flexible ultrasound probe through a standard bronchoscope. This allows for a 360-degree view of the surrounding structures. The tip is also equipped with an inflatable balloon that provides better contact and imaging. Probe resolutions are usually between 20 and 30 MHz. Radial EBUS requires localization of a particular bronchopulmonary segment via a regular bronchoscope. After the regular bronchoscope has been advanced as far as possible, a radial miniature probe is passed within a sheath through the working port of the bronchoscope. The lesion is identified, and the bronchoscope is retracted, leaving the sheath in place. Biopsy instruments can then be placed through the sheath and used to obtain tissue samples. Because the biopsy is not taken in real-time, it is important to remember that the sheath can become dislodged or manipulated, leading to an errant sample. Intraprocedural fluoroscopy can be used to reassure the bronchoscopist about the relative stability of the sheath.
Linear EBUS, the most common form, consists of a fixed array of ultrasound transducers arranged in a curvilinear fashion. Advantages of linear EBUS include utilization of color flow Doppler and real-time sonographic guided FNA of lesions. The disadvantages are that the field of vision is now 60 degrees parallel to the long axis as opposed to the 360-degree view offered during radial EBUS. One must also remember that the optical lens exits the scope at a 30-degree angle proximal to the end of the scope. This is important when maneuvering the EBUS scope through the patient’s airway. Linear EBUS is used to identify and sample masses and lesions of the central peribronchial structures, central tumors, and mediastinal and hilar lymph nodes.
The linear EBUS scope itself has both a video component and a 5-, 7.5-, 10-, or 12-MHz curved transducer. The probe utilizes a disposable latex balloon that can be filled with water to assist in creating a contact interface for transmitting the ultrasound signals. The saline line must be flushed free of air before the procedure, as air in the balloon can cause significant artifact. The EBUS scopes have a working channel between 2 and 2.2 mm in diameter that is used for the passage of a 25-, 22-, or 21-gauge needle for biopsy.
Procedural Technique:
EBUS can be performed under conscious sedation or general anesthesia. The preoperative plan and patient fitness should help dictate this choice. If a single nodal station is to be examined, conscious sedation is likely adequate. If multiple nodal stations are to be sampled, or if the patient is to undergo mediastinoscopy as well, general anesthesia is likely the better choice.
Upon entering the airway, it is important to remember that the video lens come off at a 30-degree angle. Passage through the vocal cords can be aided by slight forward flexion well above the vocal cords, and only the anterior commissure and anterior portion of the vocal cords will be in view. For mediastinal staging, the lymph node stations are accessed in the following systematic order: 11R, 10R, 7, 4R, 2R, 11L, 10L, 4L, and 2L. Station 7 may be accessed from either the right or the left mainstem bronchus. Similarly, the more distal stations, such as levels 10 and 11, can be accessed by proceeding to the level of the secondary carina (i.e. at the first bifurcation of the mainstem bronchi).
The video lens allows one to manipulate the desired portion of the airway and the ultrasound can be used to confirm the structure to be biopsied. Intraprocedural fluoroscopy can again be used if desired. Lymph nodes appear slightly echo-dense (grayish and slightly mottled) on ultrasound, as opposed to vascular structures, which appear echo-lucent (dark and homogeneous). Color Doppler can be used to confirm the absence of significant blood flow to a structure before a biopsy. Level 2 lymph nodes that are very proximal can be challenging because the flexibility of the scope is diminished once the sheath and needle are inserted. Lymph nodes larger than 5 mm are considered to be suspicious by EBUS criteria and biopsied.
Before engaging the needle, move the scope into the airway, expose the very distal tip of the needle outer sheath, and lock it in place. This only needs to be done once at the beginning, but its routine use can prevent accidental damage to the scope. Similarly, the needle should always be pulled into the scope before moving it to prevent lacerations in the airway walls.
Once the node has been visualized, engage the needle to the bronchus/trachea with the inner wire in place. This wire is then manipulated back and forth before removal to dislodge any bronchial tissue that may have been acquired during the transbronchial penetration of the needle. 10 passes of the needle are made for each sample, and samples should be obtained from each station to maximize yield and minimize sampling error. A fresh needle is used when moving from right- to left-sided lymph node stations to avoid contamination. A rapid cytology review by an onsite pathologist is performed to confirm the adequacy of the sample. Applying suction to the needle increases tissue yield, but may also increase the amount of blood in the sample and thereby affect interpretation. After completion of the biopsies, toilet bronchoscopy with a standard bronchoscope is performed to clear the airway of clots.
Navigational Bronchoscopy
A relatively new, and not yet widely available, technology is navigational bronchoscopy. The two main forms of navigational bronchoscopy are virtual and electromagnetic navigation bronchoscopy (ENB). Both techniques utilize high-quality, thin-sliced CT scans of the airways to develop a three-dimensional visualization of the airway leading to the desired lesion. This creates a very precise path that allows access to more peripheral lesions. Because of its precision, navigational bronchoscopy has significantly increased the diagnostic yield of biopsies taken from lesions less than 2 cm.
Electromagnetic navigational bronchoscopy is different from virtual bronchoscopy in that it offers real-time navigation through the use of an electromagnetic field. ENB utilizes a high-definition CT scan to develop a three-dimensional pathway to the desired lesion, similar to virtual bronchoscopy. However, the system then combines an electromagnetic board and a steerable navigation catheter to allow the operator to remotely steer the catheter down the selected path. The selected path, as well as a regular video lens, is projected via a video monitor for the operator. Biopsies can then be taken, and the catheter removed via the same path. Despite the increased yield offered by navigational bronchoscopy, its use is still relatively rare due to the technology required and the overall cost.