Download Reduce Airway Smooth Muscle (ASM)

Bronchial Thermoplasty and Guided
Bronchoscopy Part One
Wes Shepherd, MD
Director of Interventional Pulmonology
Associate Professor of Pulmonary and Critical Care
VCU Medical Center
Objectives:
• Describe the physiologic background of asthma and
tissue effects of bronchial thermoplasty
• Summarize the current treatment evidence for bronchial
thermoplasty and indications/contraindications
• Identify the various modalities of guided bronchoscopy
and their utility
Disclosure:
Financial relationships to disclose:
•Consulting– Boston Scientific, CSA Medical
•Grants - Allegro Diagnostics, Veracyte, Spiration
•Royalties – UpToDate
•No off label use of any product will be discussed
Asthma:
Prevalence, Morbidity and Mortality
22.2 Million People Are Currently
Diagnosed With Asthma
13.6 Million Unscheduled Office Visits Annually
1.8 Million Emergency Room Visits Annually
0.5 Million Hospitalizations
Annually
Approximately 4000 AsthmaRelated Deaths
Approximately 11 People Die From Asthma Each Day in the US
National Center for Health Statistics, CDC, 2005;
http://www.cdc.gov/nchs/products/pubs/pubd/hestats/asthma/asthma.html
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Stepwise Approach for Managing Asthma
6
5
4
3
2
1
High-dose ICS + LABA +
Oral Corticosteroids
and Consider Omalizumab
High-dose ICS + LABA
and Consider Omalizumab
Medium-dose ICS + LABA
Low-dose ICS +
Long-acting Beta2-agonists (LABA)
or Medium-dose ICS
Low-dose Inhaled Corticosteroids (ICS)
Short-acting Beta2-agonists
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Adapted from National Asthma Education and Prevention Program (NAEPP) Guidelines. Expert Panel Report 3: Guidelines for the Diagnosis and Management of
Asthma. National Heart, Lung, and Blood Institute, NIH Publication No. 07-4051, Revised August 2007.
Challenges in Managing Severe Asthma
• Prevalence of severe asthma (NAEPP) = 5-10%
• Many patients remain symptomatic despite standard of
care medications
• High economic costs and resource utilization associated
with medications, hospitalizations, physician visits and
lost days of work/school ~ $20.7B
• Additional therapeutic treatment options are needed
Bronchial thermoplasty:
• Asthma:
– Acute and chronic airway inflammation
– Thickened airway walls
– Increased mucous glands and goblet cells
– Increased blood vessels
– Thickening of airway smooth muscle (ASM)
Bronchial thermoplasty:
• Acute asthma attack
– Allergic stimuli
– Nonallergic – infection, cold, exercise, irritant
• Cascade always leads to ASM contraction
• Which airways cause the problem in asthma ?
– Most baseline airway resistance lies in the conducting
airways > 2 mm
– Primary site of resistance uncertain in acute asthma
• Diffuse narrowing of small airways ?
• Narrowing of large airways ?
• Generalized narrowing of all airways ?
Bronchial thermoplasty:
NEJM 2007;356:1367-69
Bronchial thermoplasty:
• Functional role of smooth muscle ?
– Extends down to respiratory bronchioles
– No strong experimental evidence for its purpose
– Proposed functions:
• Peristalsis for mucous clearance
• Promote lymphatic and venous flow
• Improving cough
• Airway stabilization
• Others
– ASM seems to be uniquely heat sensitive
Bronchial Thermoplasty – Reduces ASM
Reduce Airway Smooth Muscle (ASM)
Reduce Bronchoconstriction
Reduce Asthma Exacerbations
Improve Asthma Quality of Life
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Indications for Bronchial Thermoplasty:
• Severe asthma
• Adult asthmatics (≥ 18 years old)
• Inadequate control despite combination of
inhaled corticosteroids (ICS) and a longacting β2-agonist (LABA)
• Able to undergo bronchoscopy
Alair Bronchial Thermoplasty System Instructions for Use
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Bronchial thermoplasty:
J Bronchol 2007;14:115-123
How does BT work?
• The device consists of a
small flexible tube with four
expandable wires at the tip
• It is placed through a
standard flexible
bronchoscope through the
mouth or nose
How does BT work?
• The wires are expanded
against the walls of the airway
and thermal energy is
delivered
• This sequence of energy
delivery is continued until all
targeted airways have been
treated.
Treatment Method
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Bronchial Thermoplasty with the Alair® System
Application of RF Energy
•
Temperature controlled energy (650 C) is delivered to airway wall for 10
seconds per activation – no permanent damage to epithelium
Procedure Overview
• Patient evaluated pre-procedure to verify stability and ability to undergo
bronchoscopy
• Prophylactic OCS initiated 3 days prior, day of and day after procedure
• Local anesthesia administered – lidocaine and albuterol nebulizer
• Patient placed under moderate or deep sedation
• RF energy delivered to airways ~30-60 activations per procedure and
completed within 40-60 minutes
• Patient monitored 2-4 hours post-op and discharged home same day
•
Lung function stable within 80% of pre-procedure post BD FEV1
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Bronchial thermoplasty:
• Technique:
– Flexible bronchoscopy with moderate or deep sedation
– Tightly controlled RF energy via a catheter to airways 3 mm -10 mm
(no burn)
– Right middle lobe excluded (RML syndrome)
– Target temperature controlled to avoid perforation or airway stenosis
– 3 bronchoscopies each about 3 weeks apart
Bronchial thermoplasty:
• Technique:
–
–
–
–
–
Gel-type electrode on patient to complete circuit
RF or high frequency compatible scopes
Minimum 2.0 mm working channel
Therapeutic scope not recommended
3 procedures helps reduce procedure length, edema, and
bronchospasm
– Inspect previous treatment sites for healing
– Meticulous treatment tracking to avoid duplicate or missed
treatments (use a “map”)
Bronchial thermoplasty:
J Bronchol 2007;14:115-123
Airway Responsiveness to Local Methacholine Challenge
Canine Model: Airway on left treated with bronchial thermoplasty.
Airway onCox
right
not
treated.
et was
al. Eur
Respir
Journal. 2004;24: 659-663
Reduced Airway Smooth Muscle
•
3 years post-treatment (canine model)
Ciliated
Epithelium
ASM
ASM Reduced
Ciliated
Epithelium
Parenchyma
Parenchyma
UNTREATED
Masson’s Trichrome stain
TREATED
Bronchial Thermoplasty Clinical Studies
AIR = Asthma Intervention Research Study
AIR2 = Asthma Intervention Research 2 Study
RISA = Research in Severe Asthma Study