What is spirometry?
assesses lung function by measuring expiration volume after max inhale
differentiates between obstructive and restrictive lung disease
Includes FEV1, FVC, and % (normal 0.7)
What is FEV1? Normal values?
Forced expiratory volume in 1’s
Volume exhaled in 1st second after deep inspiration and forced expiration
80% or greater than predicted is normal
What is FVC? Normal values?
Forced Vital Capacity
Total volume of air that patient can forcibly exhale in one breath
How are the results of spirometry expressed?
FEV1 / FVC
in %, best of three readings
Normal is >0.7
What does it mean to have an obstructive spirometry pattern?
FEV1/FVC below 0.7 = obstruction
What does it mean to have a restrictive spirometry pattern?
Normal FEV1/FVC > 0.7
but FVC is low = restriction
Name a few obstructive diseases?
COPD, asthma, emphysema, bronchiectasis, bronchiolitis,
cystic fibrosis
Name a few restrictive diseases?
Pulmonary
Pulm fibrosis, Pulm oedema, TB !
Non pulm
kyphoscoliosis, neuromuscular disease, connective tissue disease, obesity, pregnancy
What is reversibility?
Bronchodilator responsiveness - see if lung function gets better with meds
If
reversible - + asthma likely diagnosis
not reversible - fixed obstructive patho
partially reversible - coexist
How might you assess reversibility?
Spirometry → Administer bronchodilator → repeat
Test with 400 microgram salbutamol
Compare and contrast asthma & COPD?
Asthma
variable airflow obstruction
reversible
COPD
fixed airflow obstruction
may be mixture
What is COPD?
Chronic Obstructive Pulmonary disease
persistent airflow limitation, not fully reversible
progressive, assoc chronic bronchitis & empysema
What is chronic bronchitis?
Cough with sputum for 3 months
2 or more years
What is emphysema?
Histological!
Enlarged airspaces distal to terminal bronchioles, with destruction of alveolar walls
loss of elastic recoil = - expiratory airflow
loss of alveoli = loss of SA for exchange
= airway collapse during expiration
Risk factors for COPD?
Cigarette smoke
Occupational exposure to pollutants, dust, chemicals, smoke
alpha-1 antitrypsin deficiency
recurrent lung infections
How might cigarette smoke cause COPD?
Mucus gland hypertrophy in large airways
= increase in WBC (N, M & L) & release of inflam mediators →
structural changes in lung = emphysema
Presentation of COPD (4)?
Productive cough
with white or clear sputum
Breathlessness - even at rest
prolonged expiration, poor chest expansion
lungs hyperinflated = barrel chest
Pursed lips on expire = prevent alveolar & airway collapse
Extra-pulmonary manifestations of COPD?
Pulmonary hypertension
= fluid retention, peripheral oedema
= (severe) RV hypertrophy, cyanosed
Weight loss, reduced muscle mass, general weakness, osteoporosis, depression
Function of alpha-1 antitrypsin in normal person?
secreted by liver, acts in parenchyma
Inhibits elastase
= protease that breaks down elastin
Elastin = important for
structural integrity of alveoli
How might alpha-1 antitrypsin deficiency caused COPD present?
Early onset, family history!
auto recess
smoking still +++ risk tho
a-1 a = hepatic secreted elastase inhibitor, deficiency = breakdown of alveoli = emphysema
Investigations for COPD (4)?
Lung function test
FEV < 80
FEV1/FVC < 0.7 = obstruct
CXR / CT
normal / hyper inflated lungs = low flattened diaphragm, long narrow heart shadow
reduced peripheral lung markings
bullae = airspace >1cm, complete destruct of lungs
FBC = chronic hypoxia
alpha-1 antitrypsin levels / genotypes
esp in premature disease & lifelong non smokers
What is peak flow?
= test of peak flow rate during forced expiration following max inspiration
Varies with:
diurnal (high afternoon low early)
age, gender, height
How might you differentiate between asthma & COPD (in investigations)?
Repeat peak flow to exclude asthma
Classification of stages of COPD?
Stage 1 - FEV1 <80%
Stage 2 - FEV1 50-79
Stage 3 - FEV1 30-49
Stage 4 - FEV1 <30%