Bronchoscopy

1 What is flexible bronchoscopy?

Bronchoscopy literally means “to see the airways.” This procedure allows visualization of the upper airways, trachea, and bronchi. Flexible bronchoscopy uses a small-caliber fiberoptic scope, which is passed through the nose or mouth or through a tracheostomy or endotracheal tube (Fig. 17-1). The bronchoscope is then directed down the trachea to the main carina (Fig. 17-2) and beyond to the regions of interest. In most patients, the airways can be visualized at least to the segmental bronchi.

Figure 17-1 Flexible bronchoscopy

Figure 17-2 Bronchoscopic view of the distal trachea, main carina, and right and left main stem bronchi.

2 How is flexible bronchoscopy performed?

Flexible bronchoscopy can be performed at the bedside or in a specialized suite with the assistance of a nurse and a respiratory therapist. Preparation includes the following steps:

3 How is rigid bronchoscopy different from flexible bronchoscopy?

Rigid bronchoscopy is performed while the patient is receiving mechanical ventilation under general anesthesia, with use of a rigid hollow tube that provides a large working channel and direct illumination. This technique is preferable to flexible bronchoscopy when more suction is required (as in the work-up of hemoptysis), during removal of some foreign bodies, during surgical or laser removal of endobronchial lesions, or in the placement of endobronchial stents. Rigid bronchoscopy requires a stable cervical spine and the ability to manipulate the mandible.

4 When should intubation be considered before bronchoscopy?

A spontaneously breathing patient scheduled to undergo flexible bronchoscopy without an artificial airway or mechanical ventilation should be cooperative, without violent coughing, and without risk for upper airway obstruction or hypoxic or hypercarbic respiratory failure. Patients who do not fit these criteria, but in whom bronchoscopy is considered a necessary procedure, may require intubation before the procedure. In all cases, equipment for endotracheal intubation should be easily accessible.

5 How is bronchoscopy different for patients receiving mechanical ventilation?

Fiberoptic bronchoscopy can be performed through an endotracheal tube at least 7.0 mm in diameter. Topical anesthesia is achieved with 1 to 2 mL of 2% lidocaine through the endotracheal tube, followed by additional boluses as needed during the procedure. A silicone-based lubricant is applied to the bronchoscope to facilitate passage through the endotracheal tube. The bronchoscope will partially obstruct the tube, causing increased airway pressure and potentially increased air trapping. The respiratory therapist should set the ventilator on a volume mode with increased peak airway pressure limits to ensure that the patient receives adequate minute ventilation. The fractional concentration of oxygen in inspired gas (FiO₂) should be increased (usually to 1.0) because bronchoscopy and lavage may cause transient hypoxia.

6 What are the indications for bronchoscopy in the intensive care unit (ICU)?

Bronchoscopy allows inspection of the airways, collection of samples from the lower airways, and performance of various interventions (Table 17-1). In the ICU, it is most commonly used to diagnose infection via bronchoalveolar lavage (BAL) or protected specimen brush. In BAL, the tip of the bronchoscope is wedged into a subsegmental bronchus while aliquots of saline solution (typically 30 mL each) are injected and aspirated into sterile traps. Alveolar contents are collected while the bronchoscope position prevents flooding of other regions of the lung. The protected specimen brush is a sterile brush with a gelatin cap that is inserted into a potentially infected area, agitated, then withdrawn and sent for culture.

^{Table 17-1} Indications for bronchoscopy

7 What other kinds of samples can be collected by bronchoscopy?

8 What is endobronchial ultrasound examination (EBU)?

EBU uses a specialized bronchoscope with a small ultrasound transducer at its tip. In addition to direct visualization of the airways, the operator is able to see ultrasound images of the tissue structures deep to the airway mucosa, such as lymph nodes and blood vessels. EBU allows more precise sampling of lymph nodes or other submucosal masses than blind needle aspiration. It is most often used in the staging of lung cancer, often in conjunction with transesophageal ultrasound examination. The sensitivity of these ultrasound-assisted biopsy techniques rivals surgical mediastinoscopy while incurring less morbidity, and they are increasingly used in this setting. It is not commonly performed in the ICU.

9 List the absolute and relative contraindications for bronchoscopy

10 What are the potential complications of bronchoscopy?

Flexible bronchoscopy is generally a safe procedure. However, complications do occur, with an incidence in observational studies of 0.1% for death and 2% to 5% for major complications (Table 17-2). Sources of complication include the bronchoscopic procedure itself and anesthetic or sedative medications.

^{Table 17-2} Potential complications of bronchoscopy

11 What is the role of bronchoscopy in the diagnosis of community-acquired pneumonia (CAP)?

CAP in an immunocompetent host does not require microbiologic confirmation by bronchoscopy and is typically treated with empiric antibiotics. However, bronchoscopy may be indicated in patients with preexisting lung disease, immunosuppression, or critical illness because the microbiologic flora involved are less predictable. In patients whose conditions fail to respond to initial treatment for CAP, bronchoscopic sampling may provide information about bacterial resistance or atypical organisms or may reveal noninfectious etiologies.

12 Discuss the role of bronchoscopy in a patient with immunosuppression and pulmonary infiltrates

The differential diagnosis of pulmonary infiltrates in an immunocompromised host is broad and includes infectious and noninfectious etiologies. Bronchoscopy is particularly useful in these patients to guide therapy by collecting samples that are analyzed by culture, special stains, and serologies. These methods are useful in the diagnosis of infections with Pneumocystis jiroveci, atypical bacteria, viruses (e.g., cytomegalovirus, respiratory syncytial virus, adenovirus), fungal pathogens, and mycobacteria. In addition, bronchoscopy and cytology may reveal alveolar hemorrhage, malignancy, or other noninfectious sources that are more common in this population than in immunocompetent hosts.

13 What is the role of bronchoscopy in the diagnosis of ventilator-associated pneumonia (VAP)?

The clinical diagnosis of VAP is made when a patient with an endotracheal tube has a fever or leukocytosis, a new infiltrate on chest radiograph, and purulent tracheal secretions. However, these findings are not specific for pneumonia. Patients who undergo invasive (i.e., bronchoscopic) diagnosis of VAP have less antibiotic use and a lower 14-day mortality rate than patients in whom the diagnosis made by using a noninvasive, empiric approach. Protected brush specimens or BAL samples are sent for quantitative cultures; > 10³ and > 10⁴ colonies of bacteria, respectively, are generally considered diagnostic for VAP. A recent meta-analysis and large randomized trial suggested that nonquantitative endotracheal culture diagnosis of VAP may be equivalent to bronchoscopy, but lack of adherence to antibiotic protocols and extensive exclusion criteria in these other studies call this conclusion into question. Regardless of the method of obtaining the culture, narrowing empiric antibiotic coverage on the basis of culture results is key to responsible antibiotic use in the ICU.

14 What are the alternatives to bronchoscopy for sample collection in the diagnosis of VAP?

When bronchoscopy is unavailable, quantitative bacterial culture can be obtained by other methods. Blind protected brush sampling or nonbronchoscopic (mini) BALs may be viable and less-expensive alternatives. In both techniques, a catheter is inserted into the airways without bronchoscopic guidance until resistance is encountered. Then the protected brush is extended or saline solution is injected to obtain the sample, and the apparatus is withdrawn. The data to support these alternative methods of quantitative culture are not as well established, but some studies comparing the quality of samples obtained by these methods with standard bronchoscopic techniques have demonstrated similar sensitivity and specificity.

15 Are transbronchial biopsies safe in patients receiving mechanical ventilation?

Several studies have demonstrated higher complication rates in patients with mechanical ventilation. The largest case series showed a pneumothorax rate of 14%, compared with a previously reported 5% rate in spontaneously breathing patients. Other studies identified higher rates of bleeding and pneumothorax in patients with mechanical ventilation who undergo biopsies. However, no study has identified increased mortality, and valuable diagnostic information is obtained in the majority of patients. Mechanical ventilation is therefore not an absolute contraindication to transbronchial biopsy, which may provide a less morbid alternative to surgical lung biopsy in selected cases.

16 Can BAL be safely performed in patients with the acute respiratory distress syndrome?

Yes—if the partial arterial oxygen tension (PaO₂) is at least 80 mm Hg (with an FiO₂ as high as 1.0) and if the patient has no absolute contraindications for bronchoscopy. A study in 110 patients with acute respiratory distress syndrome who met these criteria found no significant morbidity or mortality associated with bronchoscopy and BAL. The protocol included sedation to improve patient cooperation and to minimize coughing during the procedure. The investigators found a nonsustained decrease in oxygen saturation (to < 90%) in 4.5% of patients. Mild, self-limited bleeding followed the procedure in 34% of patients.

17 How is bronchoscopy used in the evaluation and management of hemoptysis in the ICU?

Flexible bronchoscopy can localize the site of bleeding and allows direct intervention to control bleeding by using local injection of cold saline solution, epinephrine, vasopressin, or fibrin. If these efforts are unsuccessful, bronchoscopy may be used to tamponade bleeding by using either the tip of the bronchoscope or a Fogarty balloon placed through the suction channel. Death by hemoptysis occurs via suffocation rather than exsanguination, and these efforts can prevent compromise of the unaffected lung until definitive action is taken to control bleeding with use of interventional radiology embolization or surgical resection. When bleeding is brisk, the small suction channel of the flexible bronchoscope may be overwhelmed; in such cases, rigid bronchoscopy may be preferable. Additional tools are available via rigid bronchoscopy, particularly laser and electrocautery.

18 What is the role of bronchoscopy in potential lung donors?

Bronchoscopy is routinely performed in potential lung donors before the decision is made to perform lung explantation. The purpose of this examination is threefold. First, the anatomy of the airways is assessed. Second, the operator searches for evidence of airway trauma, infection, or previous aspiration; it is likely that the lungs will be rejected if any of these is found. Third, samples are taken and sent for culture so that the microbiologic flora (if present) can be known before transplantation and covered in the recipient, who will soon have heavy immunosuppression.

19 Is bronchoscopy indicated for management of patients with acute lobar atelectasis?

Probably not. Bronchoscopy can be effective in improving atelectasis; however, studies have shown no added benefit of bronchoscopy over vigorous respiratory therapy alone, in patients either with intubation or spontaneously breathing. However, bronchoscopic intervention may be beneficial in some cases for the removal of retained, inspissated secretions or foreign bodies.

20 How is bronchoscopy used in performing tracheostomy in the ICU?

Bronchoscopy is often performed during percutaneous tracheostomy in the ICU to confirm tracheal puncture, to avoid injury to the posterior tracheal wall, and to ensure appropriate tracheostomy tube placement. Several studies suggest that bronchoscopic guidance reduces complications from percutaneous tracheostomy.