Flexible and Rigid Bronchoscopy in Thoracic Anesthesia




Flexible and Rigid Bronchoscopy in Thoracic Anesthesia



Manuel Granell Gil, Elena Biosca Pérez, Ruth Martínez Plumed



Abstract


Bronchoscopy can be considered among the most significant advances in diagnostics and treatment of respiratory disease. There are several types of bronchoscopies, including rigid and flexible, each with their own particular characteristics and indications. In the field of thoracic surgery, flexible bronchoscopy has a crucial importance. Flexible bronchoscopes are still a key element in the management of anesthesia for thoracic surgery, particularly in confirming the correct position of the isolation device used to achieve one lung ventilation. Parallel to the traditional use of the flexible bronchoscope in thoracic surgery, its uses in the field of interventional pneumonology continues to expand and develop. More and more procedures are being performed with both the rigid and flexible bronchoscope, which require adequate levels of sedation for tolerability and patient comfort. This presents a challenge for the anesthesiologist both because of the comorbidity of the subsidiary patients and because of the difficulties involved in ventilation and maintenance of the permeable airway. This is when the anesthesiologist has to share the airway with the surgeon and must have a close communication with the surgical team.


This review describes the use of the bronchoscope in thoracic surgery and the anesthetic management of the main branches of interventional pneumology: diagnostic and therapeutic bronchoscopy.


Keywords


flexible bronchoscope; rigid bronchoscope; thoracic surgery; interventional bronchology; diagnostic bronchology



Introduction


The complex cardiopulmonary interactions, combined with abnormal secretion and surgical impairment of lung-chest wall dynamics makes hypoxemia, hypo- and hypertension, dysrhythmia, hypercapnia, and acidosis common threats in the perioperative period. Bronchoscopy by definition is a procedure that allows for the visualization and examination of the tracheobronchial tree. This discipline has been one of the most significant advances in respiratory disease diagnosis and treatment, and is considered an essential instrument in pneumonology.1


Bronchoscopy originated at the end of the 19th ­century. Before this, direct exploration of the distal respiratory tract was considered an overly dangerous procedure. ­Nevertheless, in 1887, Dr. Gustav Killian, otorhinolaryngology specialist of the University of Freiburg in Germany, carried out the first direct laryngoscopy on a patient suffering from dyspnea, cough, hemoptysis, and foreign body aspiration. Using a Kirstein laryngoscope, Killian was able to visually inspect the primary bronchi and observe the presence of a solid foreign mass in the patient’s lungs. Through esophagoscopy and under a local anesthesia using cocaine, Killian was able to extract the foreign body successfully. History considers Killian as the father of modern bronchoscopy.


Sometime afterwards, Dr. Chevalier Jackson, a North American physician, offered an alternative without the need for a laryngoscope; the autonomous rigid bronchoscope. This self-illuminating instrument contains a small bulb at the distal extremity, providing the distinct advantage of visualizing endobronchial lesions. This can be considered one of the most significant advances in bronchoscopy, providing greater possibilities for visual diagnostics and providing possible treatments.


In 1966, Japanese physician Dr. Shigeto Ikeda, introduced the first flexible bronchoscope containing optical fibers, revolutionizing bronchial endoscopic procedures, following which, the use of rigid bronchoscopes diminished significantly. Nevertheless, toward the end of the 20th century, there was an increase in the variety of therapeutic techniques, including procedures using lasers, endobronchial implants, stents, and bronchial prosthetics, known as interventional bronchoscopy.


Anesthesiologists presently use flexible bronchoscopy (FB) in various clinical scenarios with regards to bronchoscopy, the most common of which incorporates the use of the guided insertion or optimal positioning of double-lumen tubes (DLTs) and/or endobronchial blockers for pulmonary isolation and/or separation. Moreover, bronchoscopy is useful and necessary in managing difficult airways, allowing for tracheal intubations by using FB. Other scenarios that implicate these types of instruments include the cardio thoracic surgery intensive care units (ICUs) and in procedures for interventional pneumology.



Rigid Bronchoscopy


Rigid bronchoscopy (RB) is an invasive procedure that allows for the simultaneous ventilation, oxygenation, inspection, and intervention on the airways



Composition


A rigid bronchoscope is composed of a hollow metallic tube with a bevelled distal extremity. In the proximal extremity, the “head” of the endoscope has three ports; one designated to an optic device, one for the instrument at work, and another for ventilation (lateral port). The lengths may vary between 33 cm (tracheoscope) and 43 cm (bronchoscope), while diameters may vary between 3 and 14 mm. Rigid bronchoscopes have fenestrations on the distal segment that allow for lateral ventilation when performing selective intubation.



Indications


These instruments are ideal for complex cases, allowing for greater control of the respiratory tract, respiration, blood, secretions, and obtaining large samples. RB is used to place rigid silicone tracheal stents that are used as primary treatment for lumen collapse or to stabilize a reconstructive effort of the larynx or trachea to prevent collapse.


They are frequently used for the extraction of foreign bodies and interventional pulmonary procedures such as the insertion of stents, dilation of tracheal and bronchial stenosis, as well as laser ablation. Such procedures are frequently performed under general anesthetic alongside neuromuscular blockades (Fig. 13.1).


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• Fig. 13.1 Tracheal stenosis dilation with balloon. (Courtesy of ­Edmond Cohen.)


Flexible Bronchoscopy


The flexible fiberoptic bronchoscope (FFB) has become an essential tool in the thoracic anesthesiologist’s practice over the past 25 years. It was the logical successor to the rigid intubating bronchoscope as a tool for precise positioning of transthoracic echocardiography. It is used as an intubation guide, a directed suction catheter, a short-term airway, and a therapeutic instrument in a number of perianesthetic settings. Fiberoptic bronchoscopy is the most widely performed procedure, noninvasive, simple, and associated with a lower morbidity rate (0.1%–2.5%) and a practically null mortality rate (<0.05%).2


The development of FB, as described by Ikeda in 1968, revolutionized bronchology to allow visualization of airways down to the segmental bronchi and is used in guiding the pulmonary isolation and separation procedures. Furthermore, FB is used for diagnostics for a variety of pulmonary diseases.



Composition


FFB is a flexible instrument with the length measuring between 50 and 60 cm, made from fiberoptics, and encased in a vinyl covering. The interior contains a work canal, with the last 2.5 cm having a steerable angulation. The external diameter for adults is usually between 5.2 and 6 mm, with a work canal of 2.0 and 2.8 mm, respectively. Small size FFBs from 2.0 mm to 4.0 mm are available and recently introduced as disposable for single use. Flexible video-bronchoscopes have a digital chip in the distal extremity that transmits images to a video processer for external monitoring. A newer generation of FFBs, with improved optics, a larger working channel, greater stiffness, and a more slender profile, is more easily used to assess or position a device in optimal bronchial position or within small bronchopulmonary segments and is less likely to obstruct ventilation during use with consequent air trapping and barotrauma. It is logical that the thoracic anesthesiologist with knowledge of cardiorespiratory function and the pathology of pulmonary disease, should master the use of fiberoptic instruments as an adjunctive means for precise definition of the dynamics of airway pathology, for direct control of DLT, EET, or bronchial blocker (BB) placement.3


The FFB is connected to an external light source. Image processor connections allow for the adjustment of light intensity, color, and brightness, also having the ability to save images. The majority of anesthesiologists prefer to use an external monitor, which is more comfortable, allowing access to enlarged images and is useful as a teaching tool.


Portable FFB exists that include a small screen incorporated into the head, which uses a battery that economically powers the device and also helps adjust the intensity of light. This is especially useful for procedures outside of an endoscopic unit, such as in an ICU, emergency room, or in an operating theatre.



Indications


Among the indications for FB for the anesthesiologist during thoracic surgery intraoperatively are practices related to general airways and isolation and/or separation of lungs. The latter is additionally associated with requirements for one-lung ventilation (OLV) during thoracic surgery; for example, the insertion of DLTs or a BB. Moreover, FB is fundamental throughout the postoperative periods for the diagnostics and treatment of complications associated with thoracic surgery.


FB is also considered a diagnostic procedure and has been the focus of most basic therapeutic procedures in pneumology and is used to obtain biopsies from the mediastinum and the pulmonary parenchyma, among other anomalies in the respiratory tract. From this perspective, a large number of therapeutic techniques are available, including the use of cryotherapy (Fig. 13.2) and cryobiopsies using flexible probes, coagulation with argon plasma (Fig. 13.3), and electrocautery. In other cases, these may also include the implantation of prosthetics stents and devices that can be used to place a unidirectional airways valve for the treatment of pulmonary emphysema. Although many of these techniques can be successfully carried out under moderate sedation, the complexity and longer duration of these procedures combined with the necessity to guarantee the tolerance and comfort of the patient usually makes a deep general anesthetic necessary. The type of anesthetic will be dependent on the difficulty and approximate duration of the procedure, as well as the comorbidities and level of cooperation of the patient.3


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• Fig. 13.2 Cryotheraphy.

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• Fig. 13.3 Argon on tumor tissue.


Contraindications


Contraindications are few taking into consideration the risk-benefit ratio of each disease and the contraindications of the technique itself.


Some clinical situations are considered particularly high risk, such as severe arrhythmias during the 4 weeks after an acute myocardial infarction in a patient with unstable angina. Other cases include refractory hypoxemia and the existence of uncontrolled coagulopathies in severe cases of renal failure and in the patient objection.



Flexible Bronchoscopy in Thoracic Surgery



Presurgical Diagnostics


The advantage of a flexible instrument is that it can be steered and directed around the anatomic structures. The FFB is not rigid enough to force its way past obstructions and foreign bodies. Consequently, lifting or displacing tissues the way one does with rigid instruments should not be attempted. The tip is advanced and angled by both hands to follow the most convenient, least resistant path to reach its goal. Once there, it can provide information and be used to direct drug application or suction for pulmonary toilet. Fibrobronchoscopic diagnostics before surgery is a fundamental procedure to extensively evaluate the type of tumor, the possibility of resectability, or any tracheal or main stem pathology that could interfere with the placement of isolating devices to provide OLV.4


Once the lesion has been located, biopsy forceps can be used through the working channel to obtain histologic samples for analysis. A sample of a purely cytologic nature can be obtained through brushing the area. Furthermore, in cases where the lesion is difficult to locate with bronchoscopy, obtaining distal samples can be performed via blind brushing of the area, as well as bronchoalveolar lavage (BAL). In microbiologic diagnostic cases, BAL is of great importance, while brushes and biopsies are also viable resources.5


Following an evaluation of the airway, the possibility of placing a conventional endotracheal tube (ETT) can be assessed, as well as the size of the tube. Additionally, the possibility of ventilation using a laryngeal mask or ventilation jets through a cannula can be considered. The information provided by FB can thus be considered of great value in each of these cases.



Airway Management


The patients frequently subjected to thoracic surgery are more likely to present abnormalities of the superior and inferior airways in comparison to the rest of the general population. These patients therefore potentially present with a difficult airway (DA).6 Despite the availability of other devices for airway management such as the videolaryngoscopes, FB can be considered the “gold standard” for endotracheal intubation in cases of DA.6



Use of Flexible Bronchoscopy in Difficult Airways


Handling of DAs in thoracic surgery and the need for separation can be a challenging. In high-risk situations such as hemorrhage, infection, and tracheobronchial fistulas among others, securing the airway will always be the ­priority.7


DA is the “gold standard” to perform awake intubation with FB. In cases where pulmonary isolations are absolutely necessary, tube exchangers can be used to place a DLT. Otherwise, a BB can be placed through the single lumen tube to provide lung separation. Only in those patients where mask ventilation is presumed easy, can the insertion of a DLT be performed with the aid of a videolaryngoscope as a main option.6,8,9


The direct insertion of a DLT through FB while the patient is awake is not an easy task because of the angled morphology of the distal extremity of the device, making the correct placement difficult as well as maneuvering the device through the vocal cords.


For the technique to be successful, the key is the adequate preparation of the patient before intervention. Unless specified as a contraindication, antisialogues are generally recommended, especially in cases of thoracic surgery because of the high percentage of patients who are smokers and/or chronic bronchial patients with increased basal secretions. Likewise, other common actions include a degree of sedation that allows for spontaneous ventilation and a correct topicalization of the airway with 1% lidocaine, allowing for the elimination of cough reflexes, as well as laryngospasms.10



Use of Flexible Bronchoscopy for the Correct Positioning of Double-Lumen Tubes (See Chapters 16 and 17)


To achieve an adequate OLV, two main devices are available, including BBs and DLTs. The FFB provides both diagnostic and therapeutic information when used for precise placement of lung isolation devices, selective tracheobronchial suction and lavage, and management of otherwise difficult airways. Surgical procedures in the thorax actively manipulate intrathoracic structures and may displace the tracheobronchial structure and secretion possibly requiring intraoperative bronchoscopy. Secretion obstruction, misalignment, and/or kinking of ETT and DLTs can present as clinical bronchospasm, with decreased tidal volume, air trapping, or increased intraoperative “shunt”. For these reasons, hypoxemia during OLA requires repeat endoscopy for verification of EBT or BB position.


The incorrect positioning of DLTs are one of the most common causes of hypoxemia during OLV. This then requires checking the instrument positioning after blind insertion. Although this was traditionally performed through visual inspection and monitoring, a 35% rate of malpositioning had been reported, putting the reliability of these techniques into question. Current practice, if available, recommends using an FFB (Fig. 13.4).11


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• Fig. 13.4 Left double-lumen tube position checking using flexible bronchoscopy (the semi lunar view of the blue bronchial cuff is indicated by the arrow). (Courtesy of Edmond Cohen.)

Right-sided DLTs are of particular relevance considering the increased rate of malpositioning caused by the potential obstruction of the right main bronchus orifice. With an entry of the right upper lobe of less than 2 cm from the carina, there is a narrow margin of safety for the correct position. This requires frequent monitoring. To check the position of a left DLT, an FFB is introduced through the tracheal ­lumen, observing the carina to certain that the semilunar rim of the bronchial cuff is viewed. That will ensure that the left upper lobe is not obstructed by the tip of the bronchial lumen of the DLT.


After positional changes or any alteration in gas exchanges, as well as increased airway pressures during the interoperative period, checking the position of the isolating device with FB is recommended.


Various sizes of FFB are available, with diameters of 6, 5, 4.9, and 3.9 mm. The latter is easily handled using a DLT of 37 Fr, however, it can be difficult for 35 Fr. In such a situation, an FFB of 2.2 mm without a suction channel can be used.


An additional notable device is the relatively recent introduction of DLTs with a built-in high-resolution camera, facilitating the correct positioning of the tube accompanied and aided with a continuous stream of video throughout the operation. This can also be performed without the need of a fibrobronchoscope.12

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Oct 6, 2021 | Posted by in ANESTHESIA | Comments Off on Flexible and Rigid Bronchoscopy in Thoracic Anesthesia
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