Resp 1 Flashcards
What is FEV1?
Maximal inspiration and maximal exhalation as fast as possible
Fraction of the total forced vital capacity expired in 1 second = FEV1
What is a normal/average FEV1 as a percentage?
Healthy individuals can expire approx. - 80% of vital capacity in one second
What is FVC?
forced vital capacity
the total amount of air forcibly expired
What is FEF25?
flow at point when 25% of total volume to be exhaled has been exhaled
What can FEV1/FVC ratio tell you?
IF ratio is below 0.7 = airway obstruction
IF ratio is high i.e. normal but the FVC is low = airway restriction
What are examples of obstructive respiratory disorders?
obstructive = reduction in airflow
- COPD
- Asthma
- Bronchiectasis
What are examples of restrictive respiratory disorders?
restrictive = reduction in lung volume
- Interstitial lung disease
- Scoliosis
- Neuromuscular cause
- Marked obesity
What would you see in terms of pO2 and pCO2 in Type 1 Respiratory Failure?
pO2 is low
pCO2 is low or normal
Type 1 = 1 change = low pO2 + normal/low CO2
What would you see in terms of pO2 and pCO2 in Type 2 Respiratory Failure?
pO2 is low
pCO2 is high
Type 2 = 2 changes = low pO2 + high pCO2
What are causes of Type 1 respiratory failure?
low ambient oxygen
ventilation-perfusion mismatch (P.E.)
Alveolar hypoventilation (neuromuscular disease)
Shunt (right to left shunt)
What are causes of Type 2 respiratory failure?
Increased airway resistance (COPD, asthma, suffocation)
Reduced breathing effort (drugs, brainstem, extreme obesity)
Decrease in the area of the lung available for gas exchange
Neuromuscular (GBS, MND)
Deformation (kyphoscoliosis, ankylosing spondylitis, flail chest)
What are some signs of hypercapnoea?
bounding pulse flapping tremor confusion drowsiness reduced consciousness
What is COPD? What 3 conditions are associated with it?
disease state characterized by airflow limitation that is not fully reversible
Chronic bronchitis - mucous secretion which blocks airways
Emphysema - loss of elasticity and airway collapse during expiration
Bronchiolitis - inflammation and scarring cause the small airways to narrow
What are some causes of COPD?
SMOKING
chronic exposure to - pollutants at work, outdoor air pollution, inhalation of smoke from biomass fuels
Alpha-1-antitrypsin deficiency (early onset COPD)
How would you investigate COPD?
Spirometry - FEV1/FVC ratio <0.7
Pulse oximetry - low oxygen saturation
ABG - hypercapnia, hypoxia and resp acidosis
CXR - hyperinflation, pneumonia, pneumothorax
FBC - raised haematocrit
How would you treat COPD?
SABA/SAMA
if no asthma/steroid responsiveness - add LABA + LAMA
if asthma/steroid responsive - add LABA + ICS
if either still uncontrolled add what’s missing
- LABA + LAMA + ICS
What is emphysema?
Dilation and destruction of the lung tissue distal to terminal bronchioles
Leads to expiratory airflow limitation and air trapping
Patients with emphysema referred to as pink puffers
What is chronic bronchitis?
airway narrowing and airflow limitation - hypertrophy and hyperplasia of mucus secreting glands of bronchial tree, bronchial wall inflammation and mucosal oedema
Patients with chronic bronchitis referred to as blue bloaters
What causes COPD patients to be described as pink puffers? How do they become blue bloaters?
low-normal PaCO2 due to increasing alveolar ventilation in an attempt to correct their hypoxia
In short term, rise is CO2 leads to stimulation of respiration - longer term = patients insensitive to CO2 = dependent on hypoxaemia to drive ventilation
these patients start to retain fluid and become cyanosed = blue bloaters
How does COPD present?
productive cough with white or clear sputum, wheeze and breathlessness - many years of a smokers cough
hypertension, osteoporosis, depression, weight loss
breathless at rest, prolonged expiration, chest expansion is poor and lungs are hyperinflated (barrel chest)
What is extrinsic allergic alveolitis?
Type of Interstitial Lung Disease - cellular infiltrates and extracellular matrix deposition in the lung distal to the terminal bronchiole
What are some types/causes of extrinsic allergic alveolitis?
Farmers lung - MOST COMMON - exposure to mouldy hay
Bird/pigeon fanciers lung - exposure to avian proteins in droppings
Cheese-workers lung - exposure to mouldy cheese
Humidifier fever - contaminated humidifying systems in the air conditioners
How would extrinsic allergic alveolitis present?
4-6 hrs post exposure
fever rigors myalgia dry cough dyspnoea crackles chest-tightness
resolution occurs within 24-48 hrs following removal of antigen
subacute attacks happen with less severe and more gradual onset symptoms - improvement takes weeks and months
How would you manage extrinsic allergic alveolitis?
avoid antigen
corticosteroid taper - prednisolone
What are some examples of occupational lung disorders?
Coal-workers pneumoconiosis
Silicosis - stonemasons, sand-blasters, pottery and ceramic workers
Asbestosis - roofing, insulation and fireproofing
Byssinosis - cotton mills
Berylliosis - aerospace industry, atomic reactors and electrical devices
