Flexible and Rigid Bronchoscopy in Thoracic Anesthesia

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.

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 ).

• Fig. 13.1Tracheal, 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%).

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.

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.

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.

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.

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.

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