EBV intervention in emphysemaDecember 13, 2018
Chronic obstructive pulmonary disease (COPD) is characterised by the presence of bronchitis and emphysema. The latter process, due to breakdown of elastic alveolar tissue, leads to increased lung compliance and gas trapping. Lung hyperinflation worsens with exercise, leading to breathlessness and is associated with reduced physical activity and reduced survival. Inhaled bronchodilator medications have only modest impact on the symptoms and do not alter the natural history of the disease. In selected patients with a heterogeneous pattern of emphysema, surgical resection can be targeted at the worst affected areas of lung tissue which contribute disproportionately to gas trapping and hyperinflation, and improve respiratory mechanics. Lung volume reduction surgery (LVRS) improves symptoms and prolongs survival, but can be associated with significant morbidity and a risk of death, with a cost per quality adjusted life year (QALY).
A more recent approach has
been to instead use endobronchial valves to occlude the airways supplying the worst affected part of the lung. This is intended to cause a collapse in the target lobe, with a similar impact on the function of the rest of the lung as seen in LVRS. However, atelectasis will only occur in the absence of significant collateral ventilation between the
target lobe and the adjacent one. Because of this, the success rate of valve placement in early studies was low, impacting the value of endobronchial valves as a therapeutic intervention.
Case series and single-centre trials have demonstrated that endobronchial valve treatment in patients with emphysema can lead to improvements in symptoms, lung function and exercise capacity, reduction in dynamic hyperinflation and improvements in oxygen kinetics and chest-wall synchrony. Moreover, where target lobe volume loss is seen on CT, a substantial survival benefit has been observed, compared with cases where valve treatment has been ineffective.
During a bronchoscopic procedure, endobronchial valves are placed in the airways to occlude a diseased part of the lungs and reduce hyperinflation, allowing the healthier parts of the lungs to take in more air and work more effectively. The valves are designed to be permanent, but can be removed if necessary.
The most common side effect associated Zephyr valve treatment was pneumothorax, which occurred in roughly one third of the patients. No intervention was required in about 20% of the incidents; the majority of the rest of such cases were addressed with standard medical management. Other side effects, which occurred less frequently, included COPD exacerbation, pneumonia, respiratory failure and death.
The Zephyr valve is contraindicated in patients with active lung infections; those who are allergic to nitinol, nickel, titanium or silicone; active smokers; and those who are not able to tolerate the bronchoscopic procedure.