Pathophysiology Flashcards
Types of pulmonary disease that limit exercise tolerance
- obstructive diseases (high airway resistance/obstruction)
- restrictive diseases (fibrosis-loss of alveoli, non-compliant lung)
- chest wall defects (muscle weakness/chest wall deformity)
what is CODP characterized by?
by progressive development of airflow limitation, not fully reversible, caused by chronic inflammation of the airways and lung parenchyma
COPD and mortality
- 4th leading cause of death
- only cause of death in USA that continues to climb
what causes COPD
long-term exposure to noxious gases and particles
three major mechanisms of COPD
- Loss of elasticity and alveolar attachments to airways (emphysema)
- Narrowing of small airways lumen (inflammation and scarring)
- Excessive secretion of mucus that blocks the airways
More of what COPD is characterized by
- High airway resistance (low FEV1%) –> Hyperinflation at end-expiration.
- Patients have a high functional residual capacity which encroaches on inspiratory capacity
- Because of hyperinflation inspiratory muscles work more than normal, and are mechanically inefficient.
- Skeletal muscle deconditioning and/or myopathy
emphysema and barrel chest
• Loss of elasticity (increased compliance of the lung) in emphysema leads to hyperinflation of the lungs.
• Hyperinflation leads to increased chest wall diameter (called “barrel-
chest”)
obstructive disease has lower
FEV and FEV1%
what is the limiting symptom at rest and exercise of COPD
- Dyspnea = perceived difficulty or distress in breathing
* Shortness of breath
what does poor V/Q matching lead to?
increased need for VE (higher VE ) at given work rate to eliminate CO2 and maintain PaO
why is work of breathing increased with COPD
- Due to airflow obstruction (high resistance)
* Due to inefficient breathing mechanics (hyperinflation)
COPD and energy cost of breathing
- low VO2max
- increased energy of breathing, lactic acidosis at low work rates –> When severe energy cost during exercise can reach 40%!
- This energy cost “steals” blood away from exercising muscles –> Some COPD pts limited by leg fatigue, not dyspnea, during exercise
what can therapeutic interventions that decrease work of breathing do?
increase exercise tolerance
strategies for decreasing dyspnea
- bronchodilation
- exercise therapy
- oxygen therapy
bronchodilation for decreasing dyspnea
- Decreases Hyperinflation & Dyspnea
* Increases breathing efficiency
what does oxygen therapy decrease?
- VE
- Breathing Frequency
- Dyspnea
- Hyperinflation
- Improve Metabolic Status
what is much of the disability in COPD related to?
concurrent deconditioning
maybe some evidence for disease related muscle disfunction
evidence for muscle dysfunction in COPD
- low muscle mass and strength, muscle aerobic enzymes and capillarity, and OBLA
- slow rise in VO2 at exercise onset –> increased O2 deficit and reliance on anaerobic metabolism
- exercise training improves muscle tolerance and muscle function
Potential abnormalities in muscle structure and function in patients with COPD
CS
HADH
Mechanisms Underlying Muscle Dysfunction In COPD
• Deconditioning
• Malnutrition
• Skeletal muscle myopathy
— Associated with chronic corticosteroid use
— Associated with chronic hypoxia, hypercapnia, and/or inflammatory cytokines
• Low circulating androgens
Purposes Of Exercise Training In Persons With Pulmonary Disease
Exercise training has NOT been shown to affect the progression or reversal of the actual disease pathology /mechanisms
Benefits Of Regular Exercise Training
- Improve functional capacity for daily activities (work tolerance) via
improvements in muscle fitness, flexibility, cardiorespiratory endurance - Reduced VE during submaxexercise
- Shift OBLA to higher intensity by increasing skeletal muscle aerobic
capacity - Improved coordination and economy of movement, respiratory muscle endurance, and improved work tolerance by reducing dyspnea severity during submax exercise
Selected Evidence Based Clinical Practice Guidelines for Pulmonary Rehabilitation
- Exercise training of muscles of ambulation recommended as a mandatory component of pulmonary rehabilitation for patients with COPD
- Lower-extremity exercise training at higher exercise intensity has greater physiologic benefits than lower intensity training in patient with COPD
- Both low-and high-intensity exercise has clinical benefits for patients with COPD
- Addition of a strength training to pulmonary rehab increases muscle strength and mass
- Supplemental oxygen should be used during rehab exercise training in patients with severe exercise induced hypoxemia
A major difference between testing in a patient with cardiac disease and pulmonary disease
increased emphasis on measuring pulmonary function before, during and after the testing
