ERBE flexible cryoprobes for bronchoscopic diagnosis and treatment

Introduction

Several diseases can cause stenosis (narrowing) or obstruction of the trachea (windpipe) or bronchi (the main passages) of the lungs, including tracheal and bronchial tumours. Lung cancer is one of the most common and serious types of cancer. Over 41,000 people are diagnosed with the condition every year in the UK (NHS Choices: Lung cancer). In England and Wales, about 30% of people survive for 1 year or more and about 10% of people survive for 5 years or more after they are diagnosed (Cancer Research UK, 2015). It can start in the trachea, the bronchi or the lung tissue.

Bronchoscopy is a technique used to visualise and examine abnormalities in the respiratory system. It is typically done using a flexible fibre‑optic bronchoscope, which is usually about 1 cm wide and 60 cm long and has a small camera at the end. Rigid bronchoscopes may also be used but they require a general anaesthetic and are less able to access distal areas of the lung (British Thoracic Society guideline). Bronchoscopes have a channel that can be used to pass small instruments or fluid into the lungs to collect lung tissue as part of diagnosis or therapy. Diagnostic and therapeutic procedures that can be done during a bronchoscopy include:

Several methods can be used to carry out these procedures. Forceps are typically used for biopsy samples and can be used to debulk cancerous tumours as part of treatment. However, forceps can cause bleeding and mechanical damage to tissue, and limit the sample size. This can make histological interpretation difficult. Recanalisations are typically done using brachytherapy, laser ablation, photodynamic therapy or stenting. Diseased lung tissue can be destroyed (selective tissue necrosis) using electrocautery or laser ablation.

Cryotherapy is the application of extreme cold to freeze abnormal or diseased tissue. It involves inserting a flexible cryoprobe into the instrument channel of a bronchoscope. Once the bronchoscope is in position, the cryoprobe tip is placed on the target tissue which, when frozen, sticks to the tip. Frozen tissue can then be removed for diagnosis (cryobiopsy) or as part of treatment (cryorecanalisation). Alternatively, diseased lung tissue can be destroyed by alternating between phases of freezing and thawing (cryonecrosis). The destroyed tissue can either be left in the bronchus to be resorbed by the body, be coughed out post‑operatively or be removed mechanically.

Biopsy samples taken using cryotherapy are larger and less likely to be elongated or distorted (because of crushing) than those removed with forceps (Hetzel et al. 2008, Hetzel et al. 2012, Schumann et al. 2010a). Also, flexible cryoprobes can be used to approach lesions tangentially (that is, from the side), as well as directly. This increases the number of accessible areas through which the procedure can be done. Finally, the freezing process minimises bleeding after tissue removal.

Flexible cryoprobes are indicated for use in both central and peripheral lung regions, but the scope of this briefing is limited to the use of flexible cryoprobes in the trachea and bronchi.