Bronchial Thermoplasty Periprocedural Care

Updated: Mar 08, 2019
  • Author: Said A Chaaban, MD; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Periprocedural Care

Preprocedural Planning

Patients selected for bronchial thermoplasty (BT) should be monitored by a medical team (eg, including a pulmonologist and an experienced bronchoscopist) to ensure that the patient has undergone a detailed medical evaluation. To ensure an ideal outcome, it is imperative to adhere to the recommendations derived from previous studies. [19]

The success of the procedure depends on a number of variables, including a patient profile similar to that studied in previous clinical trials, [19]  the technique of the bronchoscopist, and adequate patient management at the time of the procedure.

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Equipment

The thermal energy used in bronchial thermoplasty is delivered via the Alair System (Boston Scientific, Natick, MA; see the image below). This system consists of the Alair radiofrequency (RF) controller and the single-use catheter with an expandable four-electrode basket at one end and a deployment handle on the other.

Alair™ RF Controller & Catheter. Courtesy of Bosto Alair™ RF Controller & Catheter. Courtesy of Boston Scientific.

The Alair thermoplasty system is used in conjunction with a flexible bronchoscope with a 2-mm minimum working channel to allow the deployment of the catheter and a 4.9- to 5.2-mm outer diameter that allows access to smaller airways.

This catheter is deployed under direct visualization through the working channel. The array of electrodes at the distal tip of the catheter is expanded to contact the airway wall circumferentially, and the source energy is then activated. The electrical energy delivered is converted into heat when it meets tissue resistance. Continuous feedback to the energy generator ensures a close regulation of the degree and time of tissue heating to the desired prespecified temperature of 65°C. [22]

All accessories must be connected for the controller to deliver energy. If the array of electrodes is not in contact with the airway wall, the front panel notifies the bronchoscopist to reposition the electrode array.

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Patient Preparation

Patients are given 50 mg of prednisone 3 days before the procedure, on the day of the procedure, and after the procedure to minimize postprocedural inflammation of the airways. Nebulized albuterol (2.5-5 mg) is given before the patient undergoes screening spirometry to assess forced expiratory volume in 1 second (FEV1) and again before the procedure.

The patient should have had nothing by mouth after midnight the day before bronchoscopy to reduce the risk of pulmonary aspiration.

Anesthesia

Topical anesthesia with 5 mL of 1% lidocaine jelly is applied to the nostril being used for bronchoscopy; 2-mL aliquots of 1% lidocaine are then applied at the level of the vocal cords until the patient is comfortable with minimal cough. Additional 2-mL aliquots of lidocaine can be applied to the tracheobronchial tree. It is recommended to use a 1% concentration of lidocaine to limit the risk of lidocaine toxicity.

Positioning

The patient is placed in the supine position, and the bronchoscopist is at the head of the table.

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Monitoring & Follow-up

Because asthma is a heterogeneous disease with different phenotypes, not all patients with severe asthma will respond to BT. Biopsies, pulmonary function tests (PFTs), exhaled nitric oxide, and sputum eosinophils have been studied as markers to evaluate for treatment response; however, those markers cannot provide information regarding remodeling happening at the airway level.

Computed tomography (CT) of the chest and magnetic resonance imaging (MRI) of the chest with inhaled contrast would enable indirect evaluation of the airway. Optical coherence tomography (OCT) is a minimally invasive imaging technique that offers the benefit of visualizing airway remodeling. This modality was assessed for the selection process of BT in a pilot study performed on two patients, which concluded that a larger study was required to determine whether OCT can help select asthma patients who will benefit from BT and to evaluate long-term effects of BT. [35]

OCT may be considered as an effective screening tool for BT. The TASMA trial, a large multicenter, randomized, international trial, is investigating BT patients by OCT next to airway biopsies and radiographic imaging to evaluate for the immediate and late effects of this treatment on airway smooth muscle (ASM). [36, 37]

Helium MRI and multidetector CT have been validated for the quantification of regional pulmonary ventilation at the segmental level. The importance of those imaging studies is that they allow assessment of regional structure-function relations. This would help in the pretreatment and posttreatment assessments for BT. [38] Ventilation defects are increased in the pretreatment but get better in the posttreatment period. [39]

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