6 & 7: Respiratory Problems Flashcards
What are the benefits and drawbacks of peak flow meters?
Benefits: cheap, easy, individual monitoring
Drawbacks: effort dependent, wide range, very variable
What are the benefits of FEV1.0 over peak flow?
- Reduced variability
- Less effort dependent
- Can classify lung disease into obstructive and restrictive
What are the normal lung changes that occur with exercise?
- Increased sympathetic activity and circulating catecholamines
- Results in airway muscle relaxation
- Leads to bronchiole dilation and decreased parasympathetic activity
What are the proposed contributing factors to exercise induced bronchoconstriction?
- Airway drying
- Increased fluid tonicity
- Resulting in mast cell degranulation and release of bronchoactive mediators
What is a bronchoprovocation test?
- Test that measures lung function after exposure to common asthma triggers
- Direct: histamine, MCh
- Indirect: challenge with hypertonic saline
Why is airway resistance higher during expiration?
- Increased pressure in thoracic cavity
- Compresses airways
- Increases resistance
How does airway resistance change moving through the bronchial tree?
- Higher in large central airways
- Total cross sectional area of the small airways is enormous
- Resistance is inversely proportional to cross sectional area
Why are the small airways considered the silent zone of the lung?
- Small resistance, so large change required to be picked up on lung function tests
What is the residual volume?
Volume of air in the lungs after a full exhalation
What is the vital capacity?
Greatest volume of air expelled in the lungs after the deepest possible breath
What is the FRC?
Volume of air left in lungs at the end of a passive expiration
Pattern of breathing is determined by respiratory ____
Work
What causes late inspiratory crackles in a patient with restrictive lung disease?
- Increased basal airway closure with decreased compliance
- Breathing in not enough negative IPP generated
- Crackles heard when the small airways snap open in late inspiration
What is the most common physiological cause of dyspnoea?
Increased work of breathing (not gases)
