In the future, as at present, the internist will tap and look and listen on the outside of the chest…; the roentgenologist will continue to look through the patient; but in a continually increasing proportion of cases, the surgeon, the internist and the roentgenologist will ask the bronchoscopist to look inside the patient.
Introduction
Bronchoscopy is an essential tool in critical care medicine and an increasingly ubiquitous presence in the hospital. The ease, safety, and portability of bronchoscopy make it one of the most commonly requested invasive procedures in the ICU setting.
The ready access of bronchoscopy to intensivists has broadened the pulmonary diagnostic and therapeutic capabilities in critically ill patients, but like many technologies it also raises certain challenges in its appropriate application. Technology is not a substitute for good clinical judgment; operators must assess patient safety and perform procedures with attention to patient comfort with knowledge of potential complications and a management plan for complications including respiratory failure, pneumothorax, etc.
In this chapter I hope to outline the most common consultations and appropriate uses for bronchoscopy in the ICU. The overwhelming number of indications will be for diagnostic questions, all though some therapeutic indications exist. Common indications for bronchoscopy in the ICU are listed in Table 12.1.
Table 12.1 Indications for Bronchoscopy in the ICU
| Diagnostic | Therapeutic |
|---|---|
| Secretion/atelectasis management | Hemoptysis |
| Fever/Ventilator associated Pneumonia | Foreign body removal |
| Hemoptysis | Difficult intubations |
| Failed extubation | Percutaneous traceostomy guidance |
| Undiagnosed X-ray change/ | |
| Central airway obstruction |
Route of Bronchoscopy in the ICU
Bronchoscopy performed in the ICU on critically ill patients is safe, but an appropriate risk benefit analysis is always necessary. Bronchoscopy can be performed on both intubated and extubated patients but when performing bronchoscopy on extubated patients stability of oxygenation and ventilation must be assessed and the risk of respiratory failure either from sedation medications or the procedure itself must be evaluated.
Bronchoscopy in the Extubated Patient
Bronchoscopy on the extubated patient can be performed either via the oral route using a bite block or transnasaly. The patient must have oxygen requirements that can be managed by reasonable supplementation and cannot have impending respiratory failure or requirements for noninvasive ventilation like CPAP or BIPAP. The patient should have a mental status that permits the use of sedation and analgesia. The bronchoscopist when performing bronchoscopy on an extubated ICU patient must be skilled in intubation either by direct laryngoscopy or over a bronchoscope, in case of respiratory failure. Contraindications to flexible bronchoscopy without intubation include: (1) Respiratory rate > 30 bpm, (2) Clinical use of accessory muscles signifying impending respiratory failure, (3) PaO2 < 70 mm Hg or SaO2 < 90 percent with supplemental oxygen, (4) Requirement for minimally invasive BiCAP/CPAP ventilation, (5) Significantly altered mental status.
Bronchoscopy in the Intubated Patient
Performing bronchoscopy through an endotracheal tube (ETT) in the ICU is a common procedure. The endotracheal tube should be placed prior to the procedure if the patient’s respiratory status is felt to be fragile and the information from bronchoscopy is critical to patient care. The most common sizes for endotracheal tubes in adults are: 7.0 mm, 7.5 mm, and 8.0 mm. Bronchoscopes are commonly referred to as “diagnostic” and “therapeutic” based on the size of the suction channel and the overall size of the bronchoscope. Therapeutic bronchoscopes are larger and typically have a suction channel ≥2.8 mm, they are best suited to viscous and larger volume airway secretions. Diagnostic scopes are smaller with working channels ≤2.8 mm. The bronchoscope must easily pass through the inner lumen of the ETT and permit exhaled gas to escape to prevent air trapping, Table 12.2 shows common ETT sizes and size appropriate bronchoscopes. If the patient has a smaller-diameter ETT limiting bronchoscopy, the intensivist should consider changing the ETT to a larger diameter. Remember a smaller bronchoscope will have a smaller working channel and considerably less suctioning capability limiting visibility and decreasing suctioning of secretions and specimen acquisition. When performing bronchoscopy on the mechanically ventilated patient an adapter is required on the end of the endotracheal tube to ensure that tidal volume and PEEP are maintained during the procedure (Figure 12.1).
Table 12.2 Endotracheal Tube (ETT) Size Correlation with Bronchoscope Size
| Sizes of Scopes Internal diameter of endotracheal or tracheotomy tube at least 2 mm larger than bronchoscope diameter | |||||
|---|---|---|---|---|---|
| Bronchoscope Models | Inner Diameter of suction port | Outer Diameter of distal end of Bronchoscope | ENDTRACHEAL TUBES Sizes related to scope model size | TRACHEOSTOMY TUBES Sizes related to scope model size | |
| BF-XP160F | 1.2 mm | 2.8 mm | ETT 5.0 < | PORTEX # 6 / 5 MM ID | |
| BF-3C160 | 1.2 mm | 3.8 mm | ETT 6.0 < | PORTEX # 7 / 6 MM ID | |
| BF-P180 | 2.0 mm | 4.9 mm | ETT 7.0 < | PORTEX # 8 / 7 MM ID | |
| BF-Q180 | 2.0 mm | 5.1 mm | ETT 7.0 < | PORTEX # 9 / 8 MM ID | |
| BF-1T180 | 3.0 mm | 6.0 mm | ETT 8.0 < | PORTEX # 10 / 9 MM ID | |
| BF-XT160 | 3.2 mm | 6.3 mm | ETT 9.0 < | ||
Will not fit with tower interface and light source.
Figure 12.1 Bronchoscope and endotracheal tube adapter.
Sedation
When performing bronchoscopy on either the intubated or extubated patient in the intensive care unit sedation is required. Typical sedation involves the use of an analgesic and a sedative, the most common combination is opiates and benzodiazepines but sedation can be individualized to your specific ICU protocol. Topical sedation for both the intubated and extubated patient cannot be overlooked. In the extubated patient topical anesthesia in the posterior pharynx and airway limits the gag reflex. In the intubated patient topical anesthesia down the ETT or tracheostomy tube minimizes airway irritation and cough. When bronchoscopy is to be performed via the nasal route the nares must be adequately anaesthetized with topical gels. For ICU bronchoscopy routine neuromuscular blockade is not required.
In general patients who are not and will not need to be intubated and require bronchoscopy in the ICU should have had no oral or tube feed intake (NPO) for six hours prior to the procedure. NPO status is required to minimize the risk of aspiration and further compromise to critically ill patients; this is less of a concern in patients who already have an endotracheal tube in place. The patient can be maintained with intravenous hydration during this period.
Safety of Bronchoscopy in the Critically Ill
Flexible bronchoscopy and sample acquisition from the airways is a valuable tool of the critical care physician. Bronchoscopy is considered safe in critically ill patients with both respiratory failure and hemodynamic impairment as long as simple principles are followed. Steinberg and colleagues prospectively studied the effects of bronchoscopy with bronchoalveolar lavage (BAL) or protected brush specimen (PSB) on 110 patients who met clinical criteria for adult respiratory distress syndrome (ARDS). In their study there was no statistically significant change in the patients mean PaO2/FIO2 ratio, mean arterial pressure (MAP), or heart rate (HR) when comparing pre-procedure values to one-hour post procedure data. Approximately 5 percent of patients experienced oxygen desaturation to <90 percent none lasted longer than 15 minutes. No patients experienced prolonged effects from the transient desaturations or the procedure itself. Papazian et al focused on a group of 12 critically ill hemodynamically unstable patients who underwent bronchoscopy with BAL and PSB on inotropic or vasoactive support. No significant hemodynamic or ventilatory interventions were required during or after the procedures.
In all the studies demonstrating safety of bronchoscopy and BAL in critically ill patients safety was maintained despite the installation of 100–200 mL of 0.9 percent saline for lavage.
To safely perform bronchoscopy in critically ill patients a knowledgeable team is required. Staffing should include a respiratory therapist at the bedside for intubated and nonintubated patients, as well as a nurse present to assist with sedation and patient monitoring. The team must be familiar with bronchoscopy equipment set up, specimen acquisition, and ventilator management if relevant. A safety pause should be initiated prior to starting the procedure to insure the appropriate patient and procedure are identified and that all team members are present and focused on their responsibility. A safety checklist with indications and contraindications is outlined in Box 12.1. Bronchoscopy is relatively contraindicated in the following clinical circumstances until the acute clinical situation has stabilized: (1) PaO2 <60–80 on 100 percent FiO2, (2) acute ischemic heart disease or unstable angina, (3) hypotension with systolic blood pressure less than 90 mm Hg, (4) critical cardiac dysrhythmias, and (5) known increased intracranial pressure.
Box 12.1 Contraindications to Bronchoscopy in the ICU
Patient PaO2 < 60–80 mm Hg on 100% FiO2
Acute ischemic heart disease (MI) or unstable angina
Hypotension with systemic blood pressure < 90 mm Hg
Critical cardiac dysrhythmias
Known increased intracranial pressures
Bronchoscopy Safety Checklist
Continuous oxygen saturation monitoring
Hemodynamic monitoring cycled every 2–5 minutes
Continuous cardiac rate and rhythm monitoring
Ventilated patients increase FiO2 to 100 percent 5–15 minutes prior to procedure
Nursing support for sedation and monitoring
Respiratory therapy support for ventilator management monitoring of minute ventilation and pressure limited volume loss
Technical support to assist with procedure lavage, etc.
To safely perform bronchoscopy on critically ill patients the following is required: (1) continuous oxygen saturation monitoring, (2) monitoring of hemodynamics every 2–5 minutes, (3) In ventilated patients the FiO2 should be increased to 100 percent 5–15 minutes prior to the procedure, (4) monitoring for loss of minute ventilation and pressure limited volume loss due to the presence of the bronchoscope in the airway increasing peak airway pressures.
Therapeutic Aspiration of Secretions
One of the most common consultations for bronchoscopy in the ICU is the management of retained secretions and atelectasis. In published series from the Mayo clinic ICU from 1985 to 1988 clearance of retained secretions accounted for 50 percent of ICU bronchoscopies and in a series from the University of California Davis from 1979 to 1980 63 percent of bronchoscopies were performed for this purpose. The use of bronchoscopy for retained secretions and atelectasis is the subject of strong convictions and little data. There is little doubt that bronchoscopy for therapeutic removal of secretions and aggressive pulmonary toilet is safe but its efficacy and impact on clinical outcomes remains unresolved. In 1979 Marini et al randomized 31 patients with acute lobar atelectasis to bronchoscopy followed by chest physiotherapy for 48 hours vs. chest physiotherapy alone for the same period without bronchoscopy; there was no clinically significant difference in outcomes of the two groups. In both groups the presence of air bronchograms (Figure 12.2) resulted in delayed recovery.
Bronchoscopy and BAL should not be considered first line therapy for routine pulmonary toilet and secretion clearance in the ICU. Bronchoscopy should be considered in cases of acute lobar collapse particularly with alterations in oxygenation status if routine suctioning fails (Figure 12.3). Patients who have undergone thoracic surgery with airway manipulation are an unstudied population but may benefit from bronchoscopic therapeutic aspiration of secretions due to airway edema or airway tortuosity complicating pulmonary toilet. The viscosity of secretions is important to consider inspissated secretions which often occlude airway stents may be challenging to remove at the bedside and require more advanced endoscopic intervention (Figure 12.4).
Figure 12.3 (A) Chest X-ray with occlusion from mucous plug (B) Endoluminal view of mucous plug (C) Chest X-ray with lung expansion following therapeutic aspiration of mucous plug
Figure 12.4 (A) Silicone Y-stent with mucous impaction (B) Self expanding bronchial stent with inspissated secretions
Bronchoscopy; Febrile Neutropenia
Febrile neutropenic patients and patients with general immune compromise are a specialty group of patients often admitted to the ICU setting. Febrile neutropenia is considered an oncologic emergency and is most commonly associated with the use of chemotherapy or hematopoietic stem cell transplantation. The differential diagnosis for febrile neutropenia and pulmonary infiltrates can be broad with infection, bacterial, fungal, or viral being the most sinister. Other diagnoses include but are not limited to diffuse alveolar hemorrhage, radiation pneumonitis, drug induced toxicity, or malignancy itself.
Early use of empiric antibiotic therapy is the standard of care for this patient population, but flexible bronchoscopy is both safe and commonly used to augment the diagnostic work up. Diagnostic yield of flexible bronchoscopy in the febrile neutropenic patient in multiple studies has been shown to be approximately 50 percent. In a prospective series of neutropenic ICU patients the diagnostic yield of flexible bronchoscopy and BAL differed by cause of neutropenia. In patients who suffered febrile neutropenia as a result of high dose chemotherapy the diagnostic yield of bronchoscopy and BAL was 63 percent if the cause of neutropenia was stem cell transplantation the diagnostic yield fell to 38–47 percent.
Bronchoscopy in the febrile neutropenic patient in the ICU is safe with complications usually being minor and most always mirroring those of the general critically ill population. A unique clinical finding in this patient population in addition to their critical illness is often thrombocytopenia either as a result of medications or underlying illness. Bronchoscopy with BAL is safe in thrombocytopenic immune compromised patients with few reported incidences of life threatening epistaxis, hemoptysis, or alveolar hemorrhage.
Nearly all patients with febrile neutropenia are on empiric broad-spectrum antibiotics and bronchoscopy should not delay empiric antibiotic coverage. Published series report a change in antimicrobial therapy based on BAL results in 28–51 percent of the time. Viral and fungal disease often account for most therapeutic changes. A non-diagnostic bronchoscopy with BAL is insufficient to discontinue antimicrobial therapy in this patient population. Trans bronchial biopsy in the febrile neutropenic patient adds little to the diagnostic yield and is usually considered contraindicated in the setting of thrombocytopenia.
It is imperative that bronchoscopists coordinate with relevant infectious disease to insure all appropriate samples are sent to avoid the need for repeat procedures.
Ventilator-Associated Pneumonia
Ventilator-associated pneumonia (VAP) is a common and serious problem facing critically ill patients on mechanical ventilation. The diagnosis of VAP is made when a patient who has been on mechanical ventilation for ≥48 hours develops a new or progressive pulmonary infiltrate on X-ray and positive respiratory culture specimens. It is estimated that 8–28 percent of intubated patients requiring mechanical ventilation will develop a ventilator-associated pneumonia. Mortality associated with VAP is high between 24 and 50 percent. Given the severe consequences associated with VAP it is critical that a timely and accurate diagnosis is made. Bronchoscopy is an excellent tool for obtaining microbiology specimens, either bronchoalveolar lavage (BAL) or protected specimen brush (PSB), from focal affected areas identified on CXR in patients with suspected VAP. Quantitative cultures from BAL or PSB specimens help to tailor antibiotic selection and have been associated with decreased antibiotic usage but the impact of bronchoscopy in VAP on mortality remains controversial. Bronchoscopy should not delay antimicrobial therapy particularly in ICU cultures where 24-hour bronchoscopy services are not available.
Hemoptysis
The goals in managing massive hemoptysis are securing the airway, identification of the bleeding source, isolation of the bleeding area to prevent soiling of the unaffected lung, and cessation of bleeding. No consensus definition exists for massive hemoptysis, the literature often quotes 100–600 mL/24 hours but it is most important to understand that problems come not from blood loss but impairment in gas exchange. Four hundred milliliters of blood in the alveolar space can significantly impair gas exchange with only a minor perturbation in vital signs. Bronchoscopy and radiology imaging are potent tools in identifying the cause and location of hemoptysis. Bronchoscopy allows for direct examination of the central airways for tumors or other bleeding diathesis as well as examination of segmental orifices to reveal the potential regional source of bleeding or at a minimum lateralize the source of bleeding to the left or right lung. Timing is crucial in localizing bleeding in cases of hemoptysis. Bronchoscopy when performed early either during active bleeding or within 24–48 hours can localize the bleeding 75–85 percent of the time, if bronchoscopy is delayed greater than 48 hours localization of bleeding drops to 25–50 percent.
Computed tomography imaging is far superior to conventional chest X-ray and greatly helps the bronchoscopist by creating a potential road map of airway and parynchymal abnormalities. The intensivist must take into account the patient’s stability when considering the role of medical imaging because it would be inappropriate to transfer an unstable patient to radiology.
Localization of non-life threatening hemoptysis is best done employing the flexible bronchoscope. It is rapidly available, does not require general anesthesia, can be performed at the bedside, and allows for the most thorough airway survey. This rapid diagnostic survey helps with therapeutic planning. The primary limitations of flexible bronchoscopy are diminished visibility even in the presence of small volumes of blood and low suction capability. In the presence of active bleeding, it may be very difficult for the flexible bronchoscope to adequately obtain and maintain a clear airway, limiting both the goal of airway control, and the goal of bleeding localization.
Once the bleeding source has been localized good communication is required between the bronchoscopist and their therapeutic colleagues in interventional pulmonology, thoracic surgery, or interventional radiology. A number of interventional options are available for central airway bleeding lesions, beyond the scope of this review including heat energy sources; APC, laser, and cautery freezing delivery sources like cryotherapy are less effective in establishing hemostasis in airway bleeding. If the source of bleeding has been localized beyond the central airways good anatomical communication with interventional radiology colleagues is necessary for potential embolization procedures. In patients with known malignancy and central airway tumors consultation with interventional pulmonology colleagues or thoracic surgery for local control efforts followed by radiation oncology for more durable bleeding control.
If bleeding is extensive the use of endobronchial blockers is an important temporizing tool while awaiting more definitive therapy. Endobronchial blockers can be placed under direct vision using flexible bronchoscopy (Figure 12.5), once the blocker is inflated it should be deflated and the airway inspected at least every 24 hours.
