Endobronchial valves | Airway bypass stents | Affecting lung parenchyma | |||
Coils | Thermal vapour ablation | Sealants | |||
Mechanism of action | Implantation of unidirectional valves block inhaled air from entering targeted airways, while allowing trapped air and secretions from distal airways and parenchymal tissue to escape during exhalation | Anatomical fenestrations are created between bronchial walls and hyperinflated parenchymal tissue followed by insertion of a small drug-eluting paclitaxel-coated stent; these act as transbronchial passageways that allow decompression of the damaged tissue and increase gas flow from the hyperinflated region into the main airway during exhalation | Implantation of coils in targeted airways results in compression and retraction of the hyperinflated lung parenchyma, restoring elastic recoil of the healthier tissue | Heated water vapour is used to thermally damage lung parenchymal tissue and induce fibrotic responses; this leads to the formation of scar tissue that stimulates contraction of the lung, reducing the overall volume | Lung adhesives are locally delivered that polymerise in situ and induce inflammatory and fibrotic responses; this leads to the formation of scar tissue and reduction in lung volume |
Reported complications and adverse events | Valve migration/misplacement, granulation tissue formation, lack of benefit, pneumonia, pneumothorax, COPD exacerbations, severe haemoptysis, pulmonary infections and death | Granulation tissue formation, COPD exacerbations, respiratory infections, pneumothorax and haemoptysis | Pneumothorax, pneumonia, COPD exacerbations, chest pain and haemoptysis | Pneumonia, COPD exacerbations, respiratory tract infection, haemoptysis and death | Breathlessness, thrombosis, fever pulmonary embolus, leukocytosis, increased C-reactive protein, COPD exacerbations, pneumonia, haemoptysis, respiratory infections and death |
Reversibility | Reversible | Reversible | Partially reversible | Nonreversible | Nonreversible |
Examples | Zephyr valve (PulmonX Corp, CA, USA), The Spiration IBV Valve System (Olympus, WA, USA) | Exhale Emphysema Treatment System (Broncus Technologies, CA, USA) | RePneu# (PneumRx, CA, USA), Lung Tensioning Device (FreeFlow Medical, CA, USA) | Uptake Medical InterVapor (Broncus Technologies, CA, USA) | AeriSeal (PulmonX Corp, CA, USA) |
Examples of randomised controlled clinical trials | STELVIO, IMPACT, LIBERATE, TRANSFORM | EASE# | RENEW, RESET, EFFORT | STEP-UP | ASPIRE |
References | [7–14] | [15, 16] | [17–22] | [23–26] | [27–31] |
#: no longer available.