Lung transplantation is an increasingly successful treatment for patients with end-stage pulmonary disease. Leading indications for the surgery include, in descending order, COPD, cystic fibrosis (CF), bronchiectasis, idiopathic pulmonary fibrosis (IPF), primary pulmonary hypertension (PPH), and numerous less common conditions. Currently, one-year survival approaches 90%. Overall survival at one and five years is approximately 85% and 56% respectively.
Pulmonary infection and acute rejection are a threat to lung transplant recipients in the first weeks and months after surgery. In the long-term, infection and deterioration in lung function secondary to an irreversible condition called bronchiolitis obliterans syndrome (BOS) poses a major threat to survival. Although graft rejection and adverse effects of immunosuppressive therapy are the immediate causes of BOS, consequent damage to airway clearance mechanisms initiates a vicious cycle of pulmonary deterioration and ultimately, respiratory failure.
The mucociliary clearance (MCC) system maintains the mucus clearing ability in the lungs and lowers risk for infection. The effectiveness of MCC is significantly impaired after lung transplantation, both in the immediate post-surgical period and in the long term.
Following lung transplantation, several factors have been shown to reduce MCC including:
- Denervation or loss of normal nerve supply
- Impairment of cough function
- Abnormally thick mucus
- Immunological responses
- Adverse effects of immunosuppressive therapy
- Recurrent episodes of inflammation and infection
The consequences of retained airway mucus are recognized as a direct cause of pulmonary deterioration and a significant risk in lung transplant patients with impaired airway clearance function. To prevent or manage post-transplant complications associated with secretion retention, affected patients require aggressive, reliable daily mucus clearance. Post-surgical airway clearance therapy is routinely recommended in the literature and is increasingly reimbursed by insurance companies.
Many physicians prescribe vest therapy for post-lung transplantation patients unable to mobilize airway secretions without therapeutic intervention.