Endoscopic Management of Emphysema
Section snippets
Endobronchial blockers
The first published human data on BLVR reported the use of endobronchial blockers to occlude airways leading to emphysematous lung segments to cause resorption atelectasis. Silicone vascular balloons filled with radiopaque contrast were initially inserted bilaterally before custom-built stainless steel stents with a central occlusive biocompatible sponge were used.5 However, the high rate of endobronchial blocker migration, postobstructive pneumonia, and need for repeat endoscopic procedures
Airway bypass
The creation of extra-anatomic bronchial fenestrations to deflate emphysematous lung parenchyma is called airway bypass. This technique relies on the presence of preexisting collateral ventilation. Collateral ventilation is defined as the ventilation of alveoli through anatomic channels that bypass the airways. These pathways include interalveolar pores, accessory bronchiole-alveolar connections, accessory respiratory bronchioles, and interlobar pathways across fissures.6 Although collateral
Endobronchial valves
Endobronchial valves are designed to exclude the worst affected emphysematous regions from ventilation and reduce dynamic air trapping. If segmental or lobar resorption atelectasis can be induced as an additional result, a physiologic effect similar to LVRS is expected. Therefore, patients with heterogeneous emphysema are suitable candidates for endobronchial valve therapy. Valves allow one-way flow of secretions and air out of an occluded pulmonary segment but prevent any distal flow. The
Biologic lung volume reduction
Biologic sealants (Aeris Therapeutics, Inc, Woburn, MA, USA) aim to reduce lung volume in heterogeneous emphysema by sealing off the most damaged areas. Unlike endobronchial valves or bypass, these sealants are designed to work at the alveolar level rather than in the airways. The mechanism of action involves resorption atelectasis from airway occlusion, subsequent airspace inflammation, and finally remodeling, which will lead to scarring and contraction of lung parenchyma. A mature scar and
Airway implants
Airway implants such as nitinol coils (PneumRx Inc, Mountain View, CA, USA) of 10 to 20 cm in length were designed to induce lung volume reduction in patients with either homogeneous or heterogeneous emphysema. These implants, which are straight when housed in the delivery catheter, coil up on deployment and tether the lung (Fig. 5). This is hoped to change the elastic recoil and was shown to reduce lung volumes in explanted lungs.27 The coils are inserted via flexible bronchoscopes under
Anesthesia for BLVR
Although most BLVR modalities can be performed under moderate or deep sedation, use of general anesthesia to maintain control over the airways and minimize coughing is still the current practice. The anesthetic challenges are similar in all techniques of BLVR because of the dual considerations of avoiding auto–positive end-expiratory pressure (PEEP) and the need to recover the patients rapidly after the procedure.30 Auto-PEEP secondary to air trapping is a concern because of the degree of
Summary
BLVR, regardless of modality, appears to be safer than LVRS in terms of mortality and morbidity. This relatively better safety profile presents an attractive alternative to patients with COPD who are physiologically very fragile because of the severity of their lung disease and comorbid illnesses.
Efficacy data in the form of short-term, subjective improvement in dyspnea and quality of life are readily available from the currently published small, nonrandomized studies. This kind of data
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