Prognosis
The clinical presentation and prognosis of central airway obstruction (CAO) are as diverse as the diseases that cause them. Two prognostic extremes exist. CAO resulting from a treatable cause of respiratory distress, such as foreign-body aspiration, has an excellent prognosis once the offending agent is removed. By contrast, CAO in chronically ill patients with conditions such as severe COPD or metastatic lung cancer, presenting with a localised obstruction of the airway amenable to palliative treatment, have a poor prognosis, as treatment of the CAO may or may not marginally prolong survival.
A prospective study has shown that therapeutic bronchoscopy for malignant and non-malignant CAO significantly improves spirometry values (i.e., FVC, FEV1), quality of life, and survival rate. However, patients with malignant CAO in whom the airway patency cannot be recovered after therapeutic bronchoscopy have a poor survival rate.[133]
Malignant central airway obstruction
In the vast majority of cases, malignant airway obstructions are not curable and the approach is aimed at the palliation of symptoms (e.g., dyspnoea, cough, haemoptysis) that may be amenable to pharmacological or invasive procedures.[134] Patients and family members should be made aware of the palliative nature of these efforts. It is known that the survival of patients with untreated malignant CAO is very poor and ranges from 1 to 2 months.[135] Furthermore, their quality of life is extremely poor, and they may die with asphyxia or on mechanical ventilation support.
In patients with malignant airway obstruction, multimodal therapy and stent insertion have shown improvements in quality of life when compared with other strategies. However, comparisons against placebo or no palliative treatment are considered unethical and have thus not been made. A prospective study on patients with CAO due to advanced or recurrent lung cancer who underwent laser ablation demonstrated significant improvement in objective measures of quality of life.[136] Endobronchial use of laser and electrocautery in retrospective studies has shown successful palliation of dyspnoea and haemoptysis in 51% to 90% of patients.[2][16][17][18][22][69][74][90]
Two retrospective studies showed improved palliation and improved survival after airway stenting in advanced lung cancer.[121][135] One retrospective study found reduced survival in patients with malignant CAO and a high American Society of Anesthesiologists score, a non-squamous cell histology, in metastatic tumours, and in patients without prior specific therapy.[137] Another retrospective study demonstrated certain predictors associated with successful therapeutic bronchoscopy for malignant CAO, including distal patent airway visualised on CT imaging and during bronchoscopy.[24] The odds of successful relief of obstruction were found to be higher in non-smokers and with decreased time from radiographic finding of CAO to intervention.
A report from the American College of Chest Physicians multi-centre registry study of therapeutic bronchoscopy for malignant CAO showed a very high technical success rate (90% to 98%). The highest success rate was associated with stent placement and endobronchial obstruction. A 48% clinically significant improvement in dyspnoea was reported, and greater dyspnoea at baseline was associated with more significant improvement. With regards to health-related quality of life, 42% showed clinically significant improvement; again, greater baseline dyspnoea was associated with better results.[138]
Non-malignant central airway obstruction
Prognosis depends on the underlying disease, the extent of disease, and the clinical presentation. In general, these are treatable diseases, and in most instances are curable by surgery or endoscopic techniques. However, some non-malignant conditions (e.g., relapsing polychondritis, tracheobronchial papillomatosis) are recurrent and carry significant morbidity.
Tracheal dilation and laser debulking typically confer transient palliation of symptoms. Silicone stenting should be used as a bridge to surgery, or in patients who are poor surgical candidates. Surgical resection is considered the definitive treatment and should be considered early in the management of patients with stenosis who are operative candidates. If these general principles are followed, surgery will not be delayed by repeated trials of endoscopic treatment. However, successful endoscopic therapy may avoid the complications and discomfort associated with a major surgical procedure, particularly in patients with underlying cardiopulmonary disease or other significant comorbidities. In the hands of an experienced bronchoscopist, aggressive endoscopic management does not preclude future surgical procedures if necessary.
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