Approach

The management of central airway obstruction (CAO) is challenging and requires a multidisciplinary team approach with involvement of a pulmonologist, medical and radiation oncologist, anesthesiologist, ear, nose and throat specialist, thoracic surgeon, and interventional bronchoscopist.[58]

CAO management is largely dependent on the initial presentation. More than half of the interventions performed for an airway obstruction are done on an urgent or emergency basis.[28]

Airway obstruction presenting with imminent suffocation requires immediate action to promptly and effectively re-establish and secure a patent airway and relieve the obstruction.[18] Due to the acuity of the presentation in such patients, investigations that would normally be preliminary (e.g., high-resolution computed tomography, pulmonary function tests) and a diagnostic flexible bronchoscopy may not initially be performed.

Most patients whose presentation of CAO is benign or nonacute are treated as day-cases in an outpatient setting. These patients are observed for several hours in the recovery room and, if clinically stable after the procedure, are discharged that day.[9]

Experts generally describe a two-step treatment approach to CAO, with initial stabilization followed by the use of various airway interventions that can be divided into endoscopic, or surgical therapies.

Initial stabilization

The initial step, and a mandatory priority in the management of CAO, is to maintain adequate oxygenation and ventilation.

Patients with a subacute presentation of CAO may be treated with supplemental oxygen via nasal cannulae or a respiratory mask. In such stable patients, additional diagnostic information may be obtained via a diagnostic flexible bronchoscopy.

In patients presenting with severe tracheal or bronchial obstruction who are unstable with impending respiratory failure, initial stabilization is focused on establishing a secure airway. These patients should be evaluated and managed in an intensive care setting. The establishment of a secure airway may require endotracheal intubation or rigid bronchoscopy. In patients with severe proximal upper airway obstruction, urgent cricothyroidotomy or tracheotomy are the procedures of choice.[2][67]

Endotracheal intubation should be performed with anesthesia of the mucous membranes in an awake or mildly sedated patient who is actively breathing. Avoiding paralytics is advisable, as intubation may be difficult or impossible.[2][67] Although patients with CAO are very anxious, sedatives should be used with caution as hypoventilation may further compromise the airway.[60][82] The endotracheal tube (ETT) must be carefully advanced along the trachea, as trauma to the friable tissues may exacerbate an intraluminal obstruction and cause bleeding.[60] Fiberoptic-assisted intubation with ETT placement under direct visualization should be considered for proximal tracheal obstructions.[60] A laryngeal mask airway or suspension laryngoscopy are alternative options to avoid these complications.[82]

If there is any doubt regarding the stability of the airway in severe obstruction, rigid bronchoscopy is the procedure of choice as it provides a secure airway, enabling oxygenation and ventilation.[2][70]​ It also serves as a therapeutic tool for rapid stenosis dilation.[2][58][67]​​​​

Heliox, a mixture of 60% to 80% helium and 20% to 40% oxygen, may be used in acute patients as a bridging therapy, in order to avoid intubation, or to perform a more secure or stable intubation. It reduces the work of breathing by reducing the turbulent flow of gases in the large airways, and allows faster establishment of a laminar flow after changes in airway diameter.[15][82] This effect lowers the driving pressure required to obtain a given flow, or improves flow at the same driving pressure. The resultant reduced work of breathing allows for a more stable intubation with an ETT or rigid bronchoscopy. The major limitation of the use of Heliox is the inability to deliver gas with a fraction of inspired oxygen (FiO2) of >40%. Despite physiologic evidence and clinical reports, prospective randomized trials demonstrating improved outcomes with the use of Heliox are lacking.

If a dedicated airway team is not available, patient transfer to a specialized center should be considered after initial stabilization. If the patient presents with impending respiratory failure due to extrinsic airway compression, immediate intubation using a flexible bronchoscope passed distal to the stenosis and cleaning of the distal airways to remove pus and mucus prior to referral can be life-saving. Inflation of the tracheal cuff aids with the compression of the tumorous section, and the patient can be safely transported to a referral center for further treatment.[18]

In some cases, extracorporeal membrane oxygenation (ECMO) support may be considered if the degree of stenosis and risk of respiratory decompensation is deemed prohibitive for a conventional bronchoscopic approach.[83][84]​ The potential therapeutic adverse outcome should outweigh the risk of ECMO itself.[23][85]​​

Once initial stabilization is achieved in patients not managed with rigid bronchoscopy, or in patients who do not require an urgent intervention, a detailed and careful flexible bronchoscopy, as well as other additional studies required for diagnosis and treatment planning, may be performed.

Malignant airway obstruction

Resectable tumors

  • Radical surgical resection with systemic nodal dissection is the standard therapeutic approach in resectable tumors.[18]

Nonresectable tumors

  • Malignant CAO normally presents as advanced disease with no chance of curative surgical resection.

  • In patients with inoperable tumors of the central airway, restoration of airway patency provides palliation and may prolong life, especially in cases of CAO presenting with impending respiratory failure.[22]

  • Interventional bronchoscopy may be indicated prior to chemotherapy or radiation therapy (or when such treatment fails) in the management of nonresectable tumors, and has been shown to improve dyspnea and extubation rates, thus increasing quality of life.[29][58]

  • Bronchoscopic therapy is an alternative to surgery in cases where an otherwise resectable tumor is deemed inoperable due to the high functional or anesthetic risk to the patient.[29]

  • Although there are very few cases where nonresectable lung cancers have become operable following interventional bronchoscopic treatments,​​ therapeutic bronchoscopy can be used as a complementary tool in the combined bronchoscopic and surgical management of malignant CAO prior to curative lung surgery.[29][30][86]​​

  • Patients with inoperable lung cancer and symptomatic airway obstruction should be offered therapeutic bronchoscopy with mechanical or thermal ablation, brachytherapy, or stent placement, with the aim of improving dyspnea, cough, hemoptysis, and quality of life.[87]

  • A large retrospective study of more than 800 patients showed that interventional bronchoscopic procedures for severe neoplastic airway obstruction have an 85% success rate.[88]

Nonmalignant airway obstruction

The management of nonmalignant airway obstruction requires close collaboration with a thoracic surgeon experienced in the reconstruction of complex airway abnormalities.

The treatment of central expiratory airway collapse depends on the severity of the functional impairment, its etiology, the degree of airway narrowing, and the extent of the collapse. Tracheobronchomalacia or symptomatic severe dynamic posterior airway collapse may be managed with conservative therapy such as bronchodilators at standard doses or continuous positive pressure ventilation.[13]

In low-risk patients with focal tracheal stenosis, surgical resection with primary reanastomosis is the first-line therapy.[22] In patients with central expiratory airway collapse due to tracheobronchomalacia or excessive dynamic airway collapse, temporary airway stenting may be indicated if the patient is a candidate for tracheoplasty as there is the possibility that the symptoms will improve after stenting. A foreign body obstructing the central airway may be removed using a variety of instruments including forceps, grasping hooks or baskets, a Fogarty balloon, or a cryotherapy probe.[72]

Flexible and rigid bronchoscopy

Bronchoscopic therapy, which may be performed via flexible or rigid bronchoscopy, results in an improvement in symptoms, quality of life, and survival. However, for any therapeutically intended relief of obstruction in symptomatic patients, rigid bronchoscopy is the preferred option.[59]​ Selection of the appropriate approach among the possible endoscopic interventions (thermal, nonthermal, and radiation) depends on a number of factors, including the acuity of the presentation, the underlying cause and type of lesion, the stability of the patient, the patient's general, cardiac, and pulmonary status, quality of life, overall prognosis, physician expertise, and the technology available.[2][58][62]​​

A multimodal treatment with the combination of various endoscopic techniques is usually used, as some techniques such as laser therapy or electrosurgery with airway stenting are complementary to one another.[16][58]​ In general, endoscopic management involves less risk, discomfort, and morbidity than surgical treatment.[Figure caption and citation for the preceding image starts]: Post-lung transplant anastomotic bronchial stenosisFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@6a3c254d[Figure caption and citation for the preceding image starts]: Post-lung transplant anastomotic bronchial stenosis: right mainstem anastomosis post-multimodal endoscopic therapyFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@1fb83ba7

Rigid bronchoscopy

  • Safe and effective way of securing the airway that provides the ability to ventilate and oxygenate the patient while undertaking diagnostic and therapeutic airway interventions.[16][67][70][71][72][89]

  • The bronchoscopic modality of choice in patients with impending respiratory failure and the preferred approach for any therapeutically intended relief of obstruction in symptomatic patients.[58][59]​​

  • Allows the use of large-suction catheters to aspirate blood or debris, while the barrel may be used to dilate stenoses and as a coring-out instrument for tumor obstructions.

  • Requires general anesthesia and an operating theater.[58]

  • Ventilation can be achieved via spontaneous ventilation, spontaneous assisted ventilation, controlled Venturi jet ventilation, high-frequency ventilation, or closed-circuit positive pressure ventilation through the rigid bronchoscope.[16][60][71][82] Jet ventilation is used by an open system where a jet ventilation adapter is connected proximally in the rigid bronchoscope. Usually, 100% oxygen is injected at 50 psi with a rate of 8 to 15 breaths per minute. Since it is an open system, room air is also introduced and a variable FiO2 is transmitted to the distal airways. Potential complications include iatrogenic pneumothorax.[90]

  • Contraindications are those related to anesthesia and the anatomy of the neck and jaw (e.g., unstable cervical spine, oral or maxillofacial trauma, cervical ankylosis, or severe kyphoscoliosis).[16][71]

  • Complications are uncommon. Few data exist regarding the incidence of complications, but severe complications are rare in experienced hands. The most common complication is sore throat after the procedure. Other complications include injury to the teeth or gums, tracheal or bronchial tears, and severe bleeding. Hypoxemia-induced cardiac ischemia and arrhythmias are the most dangerous complications. The overall mortality related to rigid bronchoscopy is as low as 0.4%.[16][71][89][91]

  • A retrospective study has shown that rigid bronchoscopy and mechanical debulking as a sole therapy is safe and successful in up to 83% of cases of central airway tumors.[92]

  • Improvements have been made to the design of the rigid bronchoscope, to create a more versatile instrument.[93] Commonly used rigid bronchoscopes are the Bryan-Dumon series II and the Karl Storz rigid bronchoscope. The Hemer rigid bronchoscope has a measuring tube connected to the bronchoscope that allows the measurement of inspiratory and expiratory pressures, as well as oxygen and carbon dioxide concentrations.[94]

  • Rigid bronchoscopy requires special training. It is underutilized in the United States, as rigid bronchoscopy training is offered in only 4.4% of all pulmonary medicine programs, and 31.3% of pulmonary programs that have an interventional pulmonology service.[91]

Flexible bronchoscopy

  • Once initial stabilization is achieved, a detailed and careful flexible bronchoscopy, as well as other additional studies required for diagnosis and treatment planning, may be performed. This is not necessary in patients who are initially managed with rigid bronchoscopy or in patients who require urgent intervention.

  • Can be performed under local anesthesia with intravenous sedation, or under general anesthesia.

  • In flexible bronchoscopy procedures without an endotracheal tube (ETT), ventilation is spontaneous, while in those undertaken through an ETT or laryngeal mask airway, intermittent positive pressure ventilation is required.[60]

Thermal endoscopic airway interventions

All thermal endoscopic airway interventions can be used with either a rigid or a flexible bronchoscope.

Laser therapy[2][3][16][17][18][22][62][63][67][72][89][95][96]

  • Laser photoresection refers to the application of laser energy to produce thermal, photodynamic, and electromagnetic changes in living tissues. Several types of laser exist, including Nd:YAG (neodymium:yttrium-aluminum-garnet), CO₂ (carbon dioxide), and Nd:YAP (neodymium:yttrium-aluminum-perovskite). Nd:YAG laser is likely the most widely used type of laser for endobronchial disease.

  • Nd:YAG is a noncontact or contact technique in which energy from an Nd:YAG laser is applied to the airway tissue for the relief of malignant and nonmalignant CAO. [Figure caption and citation for the preceding image starts]: Central airway obstruction: malignant obstruction of the right mainstemFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@4ef94a97[Figure caption and citation for the preceding image starts]: Bronchoscopic therapy for central airway obstruction of the right mainstem: laser photoresectionFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@4c140f5f

  • Can be used in emergency situations and is an excellent tool for rapid endobronchial debulking, with a reported rate of lumen restoration of 83% to 93% and symptom relief of 63% to 94%.[63]

  • A “Rule of Four” for laser photoresection can be used to increase the chances of success and minimize risk:[17]

    • Duration of collapse: <4 weeks

    • Length of lesion: <4 cm

    • Distance from endotracheal tube to lesion: >4 cm

    • Distance from fiber tip to lesion (noncontact): 4 mm

    • Distance from bronchoscope to fiber tip: 4 mm

    • FiO2: <40%

    • Power (watts) - noncontact: 40 W

    • Power (watts) - contact: 4 W

    • Pulse duration: 0.4 seconds

    • Number of pulses between cleaning: 40

    • Operating room time: <4 hours

    • Laser team: 4

  • With laser resection, the vaporization of tissue is immediate, and the depth of tissue destruction is usually 3-4 mm. Excellent knowledge of the anatomy is essential to avoid complications such as major vessel perforation.

  • As the depth of tissue destruction cannot be accurately assessed by the appearance of the tissue surface, extreme caution should be taken to direct the laser beam parallel to the bronchial wall to avoid damage. To achieve an immobile field for accurate alignment of the laser beam, general anesthesia with neuromuscular relaxants is preferred to avoid movements (e.g., coughing).[60][71]

  • The only absolute contraindication is isolated extrabronchial disease.

  • In general, laser resection has a complication rate of <3%.

  • Complications include perforation (of airways, esophagus, or pulmonary artery), cardiac arrhythmias, pneumothorax (tension and nontension), hemorrhage, hypoxemia, myocardial infarction, stroke, air embolism (secondary to gas exiting the probe tip under pressure and crossing the mucosal membranes into the blood vessels through bronchovascular fistulae formed by coagulation of the tissue), and endobronchial ignition.[61] It is thus recommended that the FiO2 should not exceed 40% during the procedure.

  • Although no randomized trials exist to compare Nd:YAG laser therapy with other forms of CAO management, several retrospective studies have shown successful outcomes.[2][16][97][98][99]

Electrosurgery (electrocautery)[2][3][16][17][18][22][62][63][89][93][95][100][101][102]

  • Use of an electric current to heat and destroy tissue.

  • Contact or noncontact technique in which a high-frequency alternating electric current is delivered to the airway tissue for the relief of malignant and nonmalignant CAO. [Figure caption and citation for the preceding image starts]: Post-lung transplant anastomotic bronchial stenosisFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@6142902[Figure caption and citation for the preceding image starts]: Post-lung transplant anastomotic bronchial stenosis: electrocautery radial incisionFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@2877f18c

  • The effect on the airway tissue depends on the power used, the application time, the contact surface area, and the tissue type. The heat generated by the electric current is proportionally related to tissue resistance, and inversely related to tissue vascularity and moisture content.

  • Can be used in emergency situations and is an excellent tool for rapid endobronchial debulking, with a reported rate of lumen restoration of approximately 90%, and symptom relief of 70% to 97%.

  • Several tools exist to apply electrocautery in the airway, for example rigid electrocautery probes and forceps. For the flexible bronchoscope, electrocautery snares, knife, blunt probes, and hot forceps are available.

  • Usually a power setting of 10 W to 40 W is used with the blunt probes and 10 W to 40 W while using the snare or the electrocautery knife.[103]

  • Contraindicated in extrinsic airway compression. In patients with pacemakers or automatic implantable cardioverter/defibrillators, due to the potential for dysrhythmias or device malfunction, caution is recommended and the device should be turned off whenever possible and clinically indicated.

  • Risk of hemorrhage is between 2% and 5%. Other complications include endobronchial ignition, electric shock to the operator if appropriate grounding not in place, and airway perforation. Loss of effectiveness can occur with bleeding due to the diffusion of the current across a larger surface area.

  • As with laser and argon plasma coagulation, the FiO2 must be below 40% to avoid an airway fire.

Argon plasma coagulation (APC)[2][3][16][17][18][22][62][63][67][72][89][93][95]

  • Noncontact mode of tissue electrocoagulation in which ionized argon gas is used to conduct electric current to the airway tissue in the palliation of malignant CAO as part of multimodal treatment, and for the relief of nonmalignant endobronchial disease such as granulation tissue and airway papillomatosis.[Figure caption and citation for the preceding image starts]: Central airway obstruction: malignant obstruction of the right mainstemFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@227d5b23[Figure caption and citation for the preceding image starts]: Bronchoscopic therapy for central airway obstruction of the right mainstem: argon plasma coagulationFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@2256f606

  • Increasingly being used as an alternative to laser therapy and electrosurgery, as APC is an excellent tool for photocoagulation (hemostasis) with a rate of lumen restoration of 91%.[104]

  • Straight, radial, and lateral fire probes are available for different indications.

  • Usually a power setting of 30 W is used in the forced mode or 10 W in the pulse mode. The recommended flow of gas is from 0.3 liters per minute to 0.8 liters per minute.[103]

  • Although it has the advantage of being able to access lesions lateral to, "around the corner from," and at sharp angles to the probe, APC does not cause tumor vaporization, so other modalities are required for the debulking of large tumor masses. After applying APC to an endobronchial tumor, the operator may remove the resultant eschar and debris with suction, forceps, or cryoadhesion by using the cryoprobe.

  • Contraindicated in extrinsic airway compression. In patients with pacemakers or automatic implantable cardioverter/defibrillators, due to the potential for dysrhythmias or device malfunction, caution is recommended and the device should be turned off whenever possible and clinically indicated.

  • Complication rate of <1%. Complications include hemorrhage, airway perforation and stenosis, endobronchial ignition, and air embolism with argon gas. The FiO2 must be below 40% while using APC to avoid airway fires.

Cryotherapy[2][16][17][22][63][89][100][105]

  • Contact technique in which a cryogen (most commonly nitric oxide) is applied to the airway tissue in the treatment of malignant and nonmalignant CAO without impending respiratory failure.

  • Particularly successful in the removal of foreign objects and blood clots (via cryoadhesion), mucous plugs, granulation tissue, and polypoid lesions, with a rate of lumen restoration of approximately 80%, and symptom relief of 70% to 93%.

  • Most of the effects of cryosurgery do not occur until some hours after treatment, and historically the use of cryotherapy in the airways has been limited to nonacute or severe airway obstruction. In the literature, most cryotherapy use has been for low-grade stenosis or as adjunctive therapy. The maximal tissue destruction occurs in 1 to 2 weeks, and repeated treatments are recommended to achieve the desired effect.[106]

  • Case reports and retrospective studies have shown the use of cryotherapy for cryorecanalization to have an immediate treatment effect.[107] A large retrospective study of 225 cases found a 91% success rate with the flexible cryoprobe for cryorecanalization of malignant stenosis, with a safe profile.[108]

  • The effect on the airway tissue depends on the number of freezing-thawing cycles, the temperature reached (usually below -40°C), and the water content of the tissue, with maximal effect achieved from rapid freezing and slow thawing. Cryosensitive tissues include the skin, nerves, endothelium, granulation tissue, and mucous membranes. Connective and fibrous tissue, the nerve sheath, cartilage, and fat are cryoresistant.

  • A safe procedure with few and relatively minor complications, the most common of which are post-procedure fever, and airway sloughing requiring repeat follow-up bronchoscopies. Cryotherapy induces limited damage to the bronchial wall, with no residual stenosis, and has a markedly reduced risk for airway perforation.

Nonthermal endoscopic airway interventions

Photodynamic therapy (PDT)[2][16][17][22][62][63][89]

  • A light of specific wavelength (from a potassium titanyl phosphate [KTP] laser) is applied to the lesion via a flexible bronchoscope 24 to 72 hours after the local or systemic injection of a photosensitizing drug such as dihemato-porphyrin ester (DHE). This leads to a phototoxic reaction and tumor destruction as the photosensitizing drug is preferentially taken up by malignant cells.

  • Immediately, and 48 hours after the procedure, bronchoscopic toilet (cleaning and debulking of the area to remove tumor debris, retained secretions, and sloughed mucosa) is performed to establish airway patency and assess the necessity of further treatment.

  • Indicated in the palliative treatment of CAO without acute dyspnea, and particularly useful in distal obstructions due to malignant polypoid endobronchial masses with minimal extrinsic airway compression. Can also be given to patients who have already undergone surgery, radiation, or chemotherapy.

  • Due to the delayed response of treatment, PDT should not be used in the emergency management of acute, severe CAO.

  • The most common complication is skin photosensitivity that lasts for 4 to 6 weeks; patients must be advised to avoid sun exposure during this time. Other complications include local airway edema, strictures, hemorrhage, and fistulae formation, although PDT has a lower risk of airway perforation.

  • The effects are relatively long-lasting, and PDT has been shown to palliate airway obstruction in 80% of patients.

Airway dilation

  • Dilation of airway stenoses may be achieved with insertion of the barrel of a rigid bronchoscope or with balloon dilation.

  • Rigid bronchoscopic airway dilation can be used in emergency situations, as rapid recanalization can be achieved.[22][63][71]​ The distal end of the rigid bronchoscope acts as a corkscrew dilating a stenosis, or as an apple corer penetrating through large obstructive tumors. The barrel of the bronchoscope can be used to tamponade bleeding lesions. Large forceps may be introduced through the bronchoscope to aid in the mechanical debridement of bulky tumors, to remove foreign bodies, or to evacuate clots. A flexible bronchoscope may be used during rigid bronchoscopy to facilitate tissue debridement in angulated or distal airways. These techniques, although still commonly used, should be reserved for the most severe cases.[28]

  • Balloon bronchoplasty (BBP) can be performed during rigid or flexible bronchoscopy with or without fluoroscopy, and involves the use of increasingly larger diameter balloons filled with saline and maintained in position for 15-60 seconds to gently dilate the airway.[2][17][22][109][110] It induces less mucosal trauma and subsequent granulation tissue formation than does rigid dilation. Balloon tracheoplasty and bronchoplasty can be used in malignant and nonmalignant CAO, stenoses following surgical resections and lung transplantation, and in postintubation tracheal stenosis. [Figure caption and citation for the preceding image starts]: Post-lung transplant anastomotic bronchial stenosis: balloon bronchoplastyFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@5812f6d7 BBP results in an immediate improvement in extrinsic and intrinsic malignant CAO in up to 79% of patients and is useful in airway dilation prior to stenting. As its effects are not long-lasting, BBP dilation is usually followed by other therapies such as laser resection, radiation therapy, or stenting. Complications include stenosis recurrence, pain, mediastinitis, and bleeding, as well as airway tearing or rupture with subsequent pneumothorax or pneumomediastinum.

Airway stents[3][111][112]

  • Endobronchial prostheses of various materials can be used to support and maintain patency of the airway. Two types of stent (silicone and metallic or hybrid) are currently widely used in the airway, the most commonly used being the silicone stent, which is inserted with rigid bronchoscopy.

  • Silicone stents (e.g., Dumon stent, Montgomery T-tube, Hood stent, Reynders-Noppen Tygon stent) are complicated by a high migration rate and obstruction by granulation tissue formation at the stent-ends or by mucous secretions due to impaired mucociliary clearance.[2][67][72][113][Figure caption and citation for the preceding image starts]: Chest x-ray showing right mainstem endobronchial stent occlusion with mucusFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@4052e409

  • Silicone stents can be used in benign and malignant diseases and are the preferred stent type for benign airway diseases.[1]

  • The Dumon-Y silicone stent is particularly useful in malignant diseases involving the carina and the mainstem bronchi. One retrospective analysis has shown the safety and efficacy of a new type of self-expanding metallic Y stent.[114]

  • Hybrid stents, in theory, combine the qualities of silicone and metallic stents (e.g., the covered Wallstent, Ultraflex stent, Polyflex stent, Alveolus stent). They are available in uncovered (metallic stents) and covered (hybrid metallic stents) versions. The covered hybrid stents have the advantage of providing a mechanical barrier to tumor ingrowth.

  • Indicated in the management of extrinsic malignant compression and the maintenance of airway patency after intrinsic or mixed malignant endoscopic tumor removal.[Figure caption and citation for the preceding image starts]: Central airway obstruction: malignant obstruction of the right mainstemFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@100d50fa[Figure caption and citation for the preceding image starts]: Bronchoscopic therapy for central airway obstruction of the right mainstem: stent placementFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@eb30b94​ Although used in post-lung transplantation recalcitrant stenosis, stenting is only used in other forms of nonmalignant CAO if other treatments fail, as the complication rate of stenting in such conditions is 75%.[58][115][116]​​

  • Although self-expanding metallic stents are relatively easy to deploy without the need of rigid bronchoscopy, their complications may be severe and their use in benign diseases must be with caution. In 2005, the Food and Drug Administration (FDA) also issued a warning that the use of metallic stents should be avoided in benign diseases.

  • Provide immediate and durable palliation, with symptomatic relief achieved in up to 84% of patients.[117] Tracheobronchial stents have been shown to improve quality of life and survival in patients with advanced malignant obstruction.[113][118][119][120]

  • Associated with a high complication rate, particularly with long-term use of metallic or hybrid stents.[19] In addition to the aforementioned complications, stents may also be associated with halitosis, stent fracture, metal fatigue, airway and vascular perforations, mucosal tears, and obstruction of lobar orifices.[18][67][72][121]

  • A “stent alert” card should be given to every patient with an airway stent. It should specify the type and size of the stent, the location, and the appropriate size of the endotracheal tube to be used if an emergency intubation is required in the case of tracheal stents.[122]

Microdebrider[95][123][124]

  • A powered rotating blade results in accurate debridement of the obstruction. Simultaneous suction allows rapid removal of blood and debris with minimal trauma to the airway, although the tissue removed may not be fit for pathologic inspection.

  • The microdebrider blade may be smooth or serrated and comes in 2 lengths: 37 cm to access lesions of the trachea and the most proximal main bronchi, and 45 cm for more distal lesions. The usual speed of the blade is between 1000 and 2000 rpm.

  • Can be used for the therapy of subglottic stenosis as well as granulation tissue and malignant diseases in the trachea, mainstem bronchi, and distal bronchi.[Figure caption and citation for the preceding image starts]: Central airway obstruction: malignant obstruction of the right mainstemFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@3ccdc4d9[Figure caption and citation for the preceding image starts]: Bronchoscopic therapy for central airway obstruction of the right mainstem: post-mechanical debulkingFrom the collections of Jose Fernando Santacruz MD, FCCP, DAABIP and Erik Folch MD, MSc; used with permission [Citation ends].com.bmj.content.model.Caption@556ea596

  • It can be a good option in patients with poor pulmonary reserve since there is no need to decrease the FiO2 during tumor debulking.

  • The addition of electrocautery may be necessary to achieve hemostasis in up to 35% of patients.

  • One retrospective study found that the microdebrider is safe and effective in the management of benign and malignant central airway obstruction.[125]

Radiation (brachytherapy) endoscopic airway interventions

Endobronchial delivery of radiation is achieved via the placement of a radioactive substance (most commonly iridium-192) directly into or in close proximity to the airway tumor using a flexible bronchoscope. This results in tissue destruction through DNA mutations leading to cell apoptosis.[2][16][17][22][62][63][89][100]

Brachytherapy is indicated in the palliation of symptoms (in particular dyspnea, cough, and hemoptysis) related to airway obstruction. High-dose endobronchial brachytherapy is also successful in the treatment of excessive granulation tissue formation after lung transplantation at the anastomosis site or as a complication of airway stenting.[14][126][127]

As brachytherapy takes up to 3 weeks to be effective, it should not be used in the emergency management of acute, severe CAO. The effects of brachytherapy are long-lasting, with a reported rate of lumen restoration of 78% to 85% and symptom relief of 69% to 93%.[7]

An advantage of brachytherapy is that it can be used for tumors in areas (e.g., the upper lobe bronchi and segmental bronchi) not accessible to other treatment modalities. The delivery of brachytherapy is via low-dose-rate (LDR) or high-dose-rate (HDR) endobronchial methods. High-dose endobronchial brachytherapy may deliver higher radiation doses with less time on each fraction, thus allowing it to be used in an outpatient setting.

Brachytherapy can be used in combination with other techniques such as laser therapy or external beam radiation, with which it has synergistic effects.

Complications of this technique include hemorrhage (in particular in the right and left upper lobes and often presenting with massive hemoptysis), fistula formation to the mediastinum, arrhythmias, hypotension, bronchospasm, bronchial stenosis or necrosis, and radiation bronchitis. Fatal hemorrhage has been described in up to 32% of cases; however, it is difficult to distinguish between bleeding caused by radiation and that caused by the tumor itself.

External beam radiation (EBR)

Although an established therapy for lung cancer and considered the treatment of choice for patients with inoperable non-small-cell lung cancer, EBR is only variably effective for malignant CAO, and its effects are delayed and unreliable.

With the recent advances in interventional bronchoscopy, the treatment of patients with malignant CAO is shifting from EBR to bronchoscopy, and in centers with interventional pulmonology capabilities, the latter should now be considered as the first-line treatment.[2][62][63] Occasionally, EBR can be performed in a stable patient with an improved performance status following bronchoscopic intervention in order to consolidate the effects of this treatment.

The major limiting factor of EBR is the unwanted radiation exposure of normal tissue, including the lung parenchyma, heart, spine, and esophagus. Approximately 50% of patients treated with EBR for local control develop disease progression in the irradiated field.

The success rate of EBR therapy for hemoptysis is 84%, although it is only effective in the treatment of airway obstruction and atelectasis in approximately 20% of patients.

Surgical management

Surgery may be indicated in malignant and nonmalignant CAO, depending on the extent of malignant disease at presentation, the nature of the benign disease, and the existence of comorbid medical conditions.[58][70][128]​​​​

The surgical management of benign CAO is a highly specialized field and should be performed by a thoracic surgeon with significant experience in complex airway procedures.[129] The goal of surgery is either to increase the size of the available airway or to resect the stenotic segment. Thus the most common procedures are end-to-end anastomosis or tracheal sleeve resection.

Malignant airway obstruction

  • Surgery is the treatment of choice for early-stage non-small-cell lung cancer (NSCLC), with a >70% 5-year survival observed in stage IA disease.[30][62]​​[130]​ As 80% of patients present with stage III or IV, the overall 5-year survival is only 4%.[62][130][131]​ Thus, for most advanced lung cancer patients, management is focused on palliation of symptoms and improvement of quality of life.

Nonmalignant airway obstruction

  • Although surgical resection and anastomosis is the treatment of choice in benign tracheal strictures, tracheal resection is only possible in approximately 50% of patients who are otherwise suitable for surgery, and no satisfactory prosthesis has yet been developed that permits a more extensive tracheal resection.[128]

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