LEC 17: Pulmonary Disease - Asthma and COPD

What is asthma?

Chronic inflammatory disorder of the airways Increased responsiveness of the trachea and bronchi to various stimuli Widespread narrowing of the airways Recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning

What is the epidemiology of asthma?

Most common chronic disease among children Affects 262 million people worldwide 4.6 million Canadians, 900,000 under age 19 8% of the US population have asthma

What is the aetiology (risk factors) of asthma?

Unknown Genetic Allergies – indoor and outdoor air pollution, house dust mites, animals, moulds, and occupational exposure to chemicals, fumes or dust As lungs are developing – low birth weight, prematurity, exposure to tobacco smoke and other sources of air pollution, viral respiratory infections Obesity

What is the pathology of asthma?

Bronchial hypersensitivity Trigger Excess mucus Inflammation Epithelial & muscle damage Bronchoconstriction Bronchospasm Increased airway resistance Airway obstruction

What are asthma triggers?

Allergic Dust mites Pollens Moulds Pet danders Non-allergic Smoke Cold air Air pollutants Exercise Intense emotions

How is asthma diagnosed?

Symptoms History Lung Function Tests

What is FEV1/FVC in asthma?

FEV1 lower

What are the signs and symptoms of asthma?

Variable & reversible Shortness of Breath / Dyspnea Wheeze Chest tightness Cough

What is the prognosis of asthma?

Generally good, if managed well Inhalers Steroids reduce inflammation Bronchodilators open airways Avoid triggers Can limit PA & ADLs – less likely to meet PA guidelines 300 people in Canada die every year from an asthma attack

What is exercise for asthma?

Imperative if not meeting guidelines May provide some therapeutic benefit for people with asthma Symptoms can be provoked or worsened by exercise Reduced participation in PA/exercise/sports Deconditioning & reduced CRF Downward spiral with asthma symptoms being triggered by less intense PA & subsequent worsening of exercise tolerance Exercise can improve PA in people with asthma (RCTs): Step-based exercise prescription using pedometer Combined weight loss + aerobic & resistance exercise programme HIIT Exercise increases CRF in people with asthma (systematic reviews) Leads to general health benefits & reduced incidence of exacerbations Improved lung function & increased days without asthma symptoms (not universal findings in studies) Positively affects health-related QoL

What is exercise-induced bronchoconstriction?

Airway narrowing that occurs as a result of exercise is experienced in a substantial proportion of people with asthma, but people without a diagnosis of asthma may also experience EIB In athletes: Cold or dry air Air pollution Allergens Trichloramines in swimming pools Managed with pharmacotherapy and/or adjusted warm-up

What are the special considerations with exercise with asthma?

Individuals experiencing exacerbations of their asthma should not exercise until symptoms and airway function have improved Use of bronchodilators may be necessary before or after exercise to prevent or treat EIB Individuals on prolonged treatment with oral corticosteroids may experience peripheral muscle wasting and may benefit from resistance training Exercise in cold environments or those with airborne allergens or pollutants should be limited to avoid triggering bronchoconstriction in susceptible individuals EIB can also be triggered by prolonged exercise durations or high-intensity exercise sessions Use of a nonchlorinated pool is preferable because this will be less likely to trigger an asthma event Be aware of the possibility of asthma exacerbation shortly after exercise particularly in a high-allergen environment

What is COPD?

Persistent airflow limitation associated with an enhanced chronic inflammatory response in the airways to noxious particles or gases Encompasses Chronic Bronchitis & Emphysema Chronic Bronchitis Inflammation of the main air passages to the lungs Emphysema Abnormal and permanent enlargement of the airspaces that are distal to the terminal bronchioles, accompanied by destruction of the airspace walls, without obvious fibrosis

What is the epidemiology of COPD?

Affects 2 million Canadians 26% Canadians over 85 2nd leading cause of hospitalization (after childbirth) Causes 5% of all global deaths

What is the aetiology of COPD?

Develops gradually over time from a combination of risk factors Tobacco exposure Occupational exposure to dusts, fumes, or chemicals Indoor air pollution Early life events that prevent maximal lung growth Asthma in childhood

What is the pathology of COPD?

Exposure to smoke Inflammatory response Increase in the volume of inflammatory cells in airway wall and accumulation of mucus in airway lumen Breakdown of elastic fibers (elastolysis) Loss of alveolar attachments resulting from the destruction of alveolar septa

What are the effects of COPD?

Reduced gas exchange, permanent airspace enlargement, loss of elastic recoil, hyperinflation, and expiratory flow limitation

How is COPD diagnosed?

History Physical Exam Chest imaging Lung function test FEV1 < 80%, FEV1/FVC ratio < 0.7

How is COPD classified?

Mild, moderate, severe, very severe Based on FEV1

What are the signs and symptoms of COPD?

Dyspnea Productive cough Fatigue

What is the prognosis for COPD?

Severity of airway obstruction predicts 5-year mortality FEV1 35-55% predicted = 40% FEV1 <35% predicted = 55% Males aged 65 with COPD have reduced life expectancy Stage 1 = 0.3 years Stage 2 = 2 years Stage 3 or 4 = 6 years

What is the BODE index?

Body mass index (BMI) Obstruction (FEV1 % predicted) Dyspnea (modified Medical Research Council scale) Exercise capacity (6-minute walk)

How is COPD managed?

Quit smoking Medication – Steroids, bronchodilators, nebulisers Pulmonary rehabilitation

What is exercise in COPD?

• Disuse muscle atrophy is common

• Downward spiral of increasing ventilatory limitations, SOB & reduced PA Contributes to loss of muscle strength, power & endurance, & reduced functional ability/ADL

• Benefits of exercise occur primarily through adaptations in the musculoskeletal & cardiovascular systems that in turn reduce stress on the pulmonary system during exercise

• Exercise is an effective & potent intervention that can:

  • Improve symptoms

  • Lessen the development of functional impairment & disability

  • Increase QoL

  • Increase exercise capacity (6 min walk)

  • Decrease dyspnea

  • Reduce health-care use

  • Lowers risk of mortality

What are the special considerations with exercise with COPD?

• Individuals suffering from acute exacerbations of their pulmonary disease should limit exercise until symptoms have subsided

• Maximizing pulmonary function using bronchodilators before exercise training in those with airflow limitation can reduce dyspnea and improve exercise tolerance

• The use of oximetry is recommended for the initial exercise training sessions to evaluate possible exercise-induced oxyhemoglobin desaturation and to identify the workload at which desaturation occurred

• Supplemental oxygen is indicated for individuals with a PaO2 <55 mm Hg or an SaO2 ≤88% while breathing room air

What precautions and preparatory steps are required before initiating exercise in individuals with COPD?

• Avoid exercise during acute exacerbations until symptoms resolve

• Optimize pulmonary function with bronchodilators pre-exercise → ↓ dyspnea, ↑ tolerance

• Use pulse oximetry initially to detect exercise-induced desaturation and identify workload thresholds

• Supplemental O₂ indicated if:

• PaO₂ <55 mmHg OR

• SaO₂ ≤88% (room air)

How should exercise intensity be prescribed in COPD, and what are the limitations of HR-based methods?

• General principles:

  • Higher intensities → greater adaptations (↓ ventilation and HR at given workload)

  • Mild COPD → follow healthy older adult guidelines

  • Moderate–severe COPD → target >60% peak work rate

  • Severe/deconditioned → start light intensity, progress as tolerated

• Limitations of HR-based prescription:

  • HRrest often elevated

  • Medications + ventilatory limits blunt HR response

  • Predicted HRmax often unattainable → %HRmax/%HRR unreliable

• Preferred method:

  • Dyspnea-based prescription (Borg CR10):

  • Target: 3–6 (≈53–80% VO₂peak)

  • Patients can reliably self-regulate using dyspnea from exercise testing

What are the key physiological limitations in COPD and how should exercise training address them?

• Limitations:

  • Peripheral muscle dysfunction → major contributor to exercise intolerance

  • Associated with ↑ healthcare use, poorer prognosis, ↑ mortality

  • Dyspnea more pronounced during upper body ADLs

  • Postural impairments → ↓ thoracic mobility → ↓ lung function

• Training implications:

  • Resistance training (RT): strongly recommended (target peripheral muscle dysfunction)

  • Include upper body RT to reduce dyspnea during ADLs

  • Aerobic training: improves efficiency (↓ ventilation, ↓ HR at workload)

  • Flexibility training: improves posture and thoracic mobility → supports breathing mechanic