Technology overview

This briefing describes the regulated use of the technology for the indication specified, in the setting described, and with any other specific equipment referred to. It is the responsibility of healthcare professionals to check the regulatory status of any intended use of the technology in other indications and settings.

About the technology

Bronchial thermoplasty (BT) is a catheter‑based bronchoscopy treatment for severe, difficult to control asthma in adult patients. The Alair system is designed to help control asthma symptoms by delivering thermal energy from a radiofrequency source to reduce the amount of excess airway smooth muscle.

CE marking

The Alair BT catheter (class IIb), radiofrequency controller (class IIb) and accessory kit (class I) were first CE marked to Asthmatx, the original developer of the Alair system, in November 2002. Boston Scientific acquired Asthmatx in October 2010. The current certification, issued to Boston Scientific in July 2014, is valid until December 2018.


The Alair system consists of 2 main components:

  • A sterile, single‑use Alair catheter designed to be deployed through a standard bronchoscope. The catheter delivers radiofrequency energy through an electrode array, which expands against the airway wall to deliver energy and contracts to enable repositioning. The catheter has 4 marker bands, spaced 5 mm apart, to aid positioning for energy delivery at adjacent sites across the target airway.

  • A reusable Alair radiofrequency controller designed to connect all system components and to provide temperature‑controlled delivery of the thermal energy. The controller front panel includes 3 separate connectors for the Alair catheter, a gel‑type patient return electrode (supplied by third‑party manufacturer) used to complete the radiofrequency circuit, and a footswitch allowing the operator to start and stop thermal energy delivery. The controller incorporates a temperature control algorithm, which uses temperatures measured every 0.02 seconds by a thermocouple attached to one of the catheter electrodes. The algorithm automatically adjusts and delivers low power (up to 18 Watts), temperature‑controlled radiofrequency energy to the airway at 65°C for 10 seconds. There are no user controls for these parameters. A small display counter indicates the number of complete activations during the procedure.

The Alair system delivers BT in 3 separate treatment sessions to different sections of the lungs. The first procedure treats the airways in the right lower lobe, the second treats the airways in the left lower lobe, and the final procedure treats the airways in both upper lobes. Each session is routinely done under moderate sedation and typically takes 45 to 60 minutes.

Patients are given 40 mg to 50 mg corticosteroids daily for 3 days before the procedure, on the day of the procedure and on the day after the procedure to minimise post‑procedure inflammation.

During the BT procedure, a flexible bronchoscope is introduced into the patient's airways through the nose (or mouth if nasal access is difficult). The bronchoscope is then positioned at the first target treatment site, typically the most distal airway in the targeted lobe. The Alair catheter is introduced under direct visualisation through the bronchoscope working channel. Once in position, the electrode array is expanded until all electrodes are seen to be in contact with the airway wall. The operator presses the footswitch once to start automatic delivery of thermal energy and again to manually stop treatment, if necessary. The controller will automatically cease energy delivery if it detects atypical delivery or temperature response. The controller provides audio and visual user alerts to indicate correct energy delivery or if electrodes need to be redeployed. Following energy delivery, the electrode array is retracted and the catheter is repositioned (using the 5 mm marker bands as a guide) before the array is expanded again ready for the next activation. This process is repeated until the target lobe is fully treated, which typically involves 40 device activations.

Setting and intended use

BT is usually done as a day case at tertiary respiratory centres. Three treatments are needed, scheduled a minimum of 3 weeks apart. The Alair system is indicated as an add‑on therapy for treating severe difficult to control asthma in patients aged 18 years and older, whose asthma is not well controlled despite management at step 4/5 of the BTS/SIGN guidelines.

The system is intended to be used by qualified respiratory clinicians with experience in bronchoscopy procedures and who are specifically trained to use the Alair system. The manufacturer advises that in the NHS, most procedures are done by 2 respiratory consultants plus a nurse. There may also be an additional nurse, operating department practitioner or a specialist registrar present.

The manufacturer has listed 6 contraindications to the BT procedure using the Alair system:

  • presence of a pacemaker, internal defibrillator, or other implantable electronic devices

  • known sensitivity to medications needed for bronchoscopy, including lidocaine, atropine and benzodiazepines

  • repeat treatment (areas previously treated with the Alair system should not be treated again because of a lack of clinical data on safety and effectiveness of repeat treatments)

  • active respiratory infection

  • asthma exacerbation or changing dose (up or down) of systemic corticosteroids for asthma in the past 14 days

  • known coagulopathy.

Current NHS options

Current NHS standard therapy for asthma follows the stepwise approach in the BTS/SIGN guidelines (BTS/SIGN guideline 2014). Severe, difficult to control asthma is recognised as an area of unmet therapeutic need (NHS England standard contract 2013). Current NHS standard therapy for severe asthma is inhaled high‑dose corticosteroids, long‑acting beta 2 agonists, leukotriene receptor antagonists, theophyllines, oral corticosteroids and smoking cessation if clinically appropriate (NICE asthma pathway 2016). NICE's technology appraisal guidance on omalizumab for treating severe persistent allergic asthma recommends the drug as an option when given as an add‑on to optimised standard therapy in people 6 years and older, with confirmed presence of a perennial allergy, who need frequent treatment with oral corticosteroids.

Currently BT is available in around 9 tertiary respiratory centres in England, with over 215 procedures done (Burn et al. 2015).

NICE has issued interventional procedures guidance on bronchial thermoplasty for severe asthma that states the procedure should only be used with special arrangements for clinical governance, consent and audit or research. Actions required include submitting details of all patients having the procedure to the 'difficult asthma' registry.

NICE is not aware of any other CE‑marked devices that have a similar function to the Alair system.

Costs and use of the technology

The cost of 3 procedures requiring single‑use catheters at £2,310 each and a patient return electrode at £4.04 each is £6,942.12. Use of the Alair system also requires an initial capital cost (a one‑time payment) of up to £31,500 for the radiofrequency controller. Assuming a 10‑year lifespan for the radiofrequency controller and that each centre does 30 to 60 procedures each year (10 to 20 patients), the cost ranges from £157.50 to £315.00 per patient. The estimated total cost per patient thus ranges from £7,099.62 to £7,257.12.

Hospitals may choose to buy a service agreement at a cost of £1,663 to £1,950 per year depending on its length. This covers the cost of replacing a controller or parts of the controller if anything goes wrong. No servicing or maintenance is needed. The manufacturer provides initial set‑up and training, education and ongoing clinical support at no extra cost.

Each BT procedure requires a pre‑assessment review and up to 4 follow‑up visits in the first year, as well as the procedure itself. This assumes the assessment is informed by standard investigations and no additional investigations are needed at follow‑up. In 2014/15, the mean cost for a therapeutic bronchoscopy was £746 and the mean cost for a respiratory medicine outpatient appointment was £156 (Department of Health, 2015). If all appointments are assumed to be in addition to the current care pathway, the cost consequences are about £1,525 per patient, falling to about £900 if only the pre‑assessment visit and procedure are considered additional to the current pathway. In practice, most patients are under regular follow‑up so the 4 visits would not be additional.

Further resources and costs should be considered to manage respiratory adverse events during treatment.

Additional costs include the staffing and resource requirements associated with complex bronchoscopy procedures, particularly more detailed pre‑bronchoscopy assessments and increased monitoring of patients (NIHR 2011). An estimate based on clinical trial data suggests that around 3.4% of bronchoscopies may result in a hospitalisation (NIHR 2011).

Potential savings arise from fewer subsequent attendances at primary care and unscheduled care through reduced symptoms and possibly fewer hospital admissions for severe asthma exacerbations (NIHR 2012).

Likely place in therapy

BT (and therefore the Alair system) is used in specialist centres that manage severe difficult to control asthma, as an add‑on treatment at step 4/5 of the BTS/SIGN guidelines. This may include frequent courses of oral corticosteroid or maintenance oral corticosteroid with documented evidence of medication adherence, following systematic specialist review of symptoms. Patient selection and treatment is done by a specialist respiratory team.

Specialist commentator comments

One specialist commentator noted that the estimate of 3.4% of bronchoscopies resulting in hospitalisation assumes that patients have the same severity as those from the clinical trials that informed the estimate. The commentator advised that currently, most cases treated are materially more severe than those included in clinical trials, having higher baseline exacerbation and hospitalisation rates than patients in the trials. The cost calculation using clinical trial data may thus underestimate the potential reduction in emergency room and hospital admissions given that the baseline is substantially higher. The specialist added that competing treatments may need more intensive management than BT; for example, omalizumab requires around 16 visits for 2‑ to 4‑weekly subcutaneous injections.

Two specialist commentators advised that a UK cost analysis using patients in the BTS difficult asthma registry is underway, with one adding that the current cost estimate for the BT package in their centre is about £13,000 per patient for all treatments and clinic visits.

Three commentators noted there are no phenotypes or biomarkers to direct clinicians as to which patients are most suitable for BT. One specialist commentator suggested that BT should be indicated when asthma is not well controlled despite treatment with inhaled corticosteroids and when other standard add‑on therapies (such as leukotriene‑antagonists, anti‑muscarinic inhalers and theophyllines) have been tried.

Equality considerations

NICE is committed to promoting equality, eliminating unlawful discrimination and fostering good relations between people with particular protected characteristics and others. In producing guidance and advice, NICE aims to comply fully with all legal obligations to:

  • promote race and disability equality and equality of opportunity between men and women

  • eliminate unlawful discrimination on grounds of race, disability, age, sex, gender reassignment, marriage and civil partnership, pregnancy and maternity (including women post‑delivery), sexual orientation, and religion or belief (these are protected characteristics under the Equality Act 2010).

The device is indicated for treating severe asthma only in people aged 18 years and older. Age is a protected characteristic under the Equality Act (2010).