Lung function test 2 Flashcards
Maximus inspiration
Maximum air in and out
Residual volume
Air left inside lungs after full expiration
How do you diagnose lung issues
- Evaluation of signs and symptoms (cough, wheeze, stridor, SOB)
- Abnormal imaging
- Preoperative assessment
- Monitoring toxic therapies
What is spirometry?
Measures flow and volume
Volume vs time
Determines FEV1, FVC and FEV1/FVC
Obstructive spirometry
Decreased FEV2
Decreased FVC
Decreased FEV1/FVC
Differential diagnosis
Asthma COPD Bronchiectasis Bronchiolitis Upper airway obstruction
What is a wheeze?
Lower airway obstruction heard on expiration
Obstruction at bronchioles increasing resistance
Wheeze and expiration
Greater expiratory effort only increases positive intrapleural pressure, compressing small intrathoracic airways further and limiting expiratory flow
What is a stridor
Upper airway obstruction heard on inspiration
Outside thoracic cavity
What causes stridor
Tumours, infection, swelling, VC palsy or foreign body
Inspiration and stridor
Greater inspiratory effort creates more negative pressure in thorax which narrows obstructed part of airway
Expiration and stridor
Greater positive pressure generated within airways helps increase upper airway diameter, improving air flow
What is spirometry?
- Measures forced inspiratory and expiratory volume
- Evaluates upper airway obstruction
- Investigates fixed upper airway obstruction (tracheal stenosis, upper airway tumours)
- Investigates variable extra-thoracic obstruction (above sternal notch, goitre, vocal cord paralysis)
- Investigates intrathoracic obstruction (below sternal notch, tracheomalacia, inflammatory disorders)
What is body plethysmography?
Inspiratory effort against closed shutter produced measurable pressure and volume changes in box and lungs
What is diffusing capacity?
- Diffusing capacity of lungs for CO (DLCO)
- Measures ability of lungs to transport inhaled gas from alveoli to pulmonary capillaries
- DLCO or TLCO
