Obstructive Airway Disease

Question 1

What are the 2 Obstructive Airway Diseases?

Answer 1

Asthma & COPD

Question 2

Asthma:

Prevalence?

Answer 2

inc prevalence

Question 3

Why is Asthma Prevalence increasing?

Answer 3

Hygiene hypothesis and inc in genetic hypersensitivity predisposition

Question 4

What are the different classes of asthma?

Answer 4

Allergic, non-allergic, acute exacerbation

Question 5

What is Asthma…

Answer 5

Reversible airway obstruction, inflammation of airways due to airway hyper-responsiveness

Question 6

What is the pathophysiology of asthma?

Answer 6

Bronchoconstriction due to chronic airway inflammation & airway remodelling…

Question 7

What drives inflammation in asthma pathophysiology?

Answer 7

TH1 & TH2 lymphocytes activate mast cells and eosinophils

• Mast Cells: release pro-inflam mediators which act on mucus secreting cells & ASM
• Eosinophils: release proteins that are toxic to epithelial cells

Question 8

What does airway inflammation cause as a repercussion in asthma?

Answer 8

Airway remodelling; structural changes which alter airway physiology causing symptoms

Question 9

Give 2 examples by which the airways are remodelled?

Answer 9

• depositions of proteins and cellular infiltration causing swelling of the submucosa resulting in airway narrowing
• swelling outside ASM layer causes a reduction in retractile forces of alveoli so airways close more

Question 10

Asthma triggers (aetiology)?

Answer 10

atmospheric pollution, cold air, allergen, occupational sensitisers, drugs, irritants, viral, emotion, associated atopy (e.g. eczema), not using inhaler properly

Question 11

Presenting symptoms of asthma…

Answer 11

wheezing, SOB, nocturnal exacerbations, non-productive cough

Question 12

Asthma investigations…

Answer 12

blood test (eosinophilia >4%) 
PFTs (PEFR, spirometry) 
Exercise test, exhaled NO, skin test for allergen

Question 13

Asthma treatment…

Answer 13

Avoid allergen

1. SABA (occasional symptoms)
2. SABA & Inh Corticosteroids (CS) + xanthine (e.g. theophylline)/ cromone (daily symptoms)
3. LABA & Inh CS + CysLT1/ xanthine (severe)
4. inc dose of inh CS & LABA & SABA/CysLT1/ xanthine (severe but not responding to 3)
5. step 4 + oral CS (e.g. prednisolone) (severe and deteriorating)
6. Hospital Admission

Question 14

Presentation of acute exacerbation of asthma (AEoA)

Answer 14

progressive shortening of breath, accessory muscles engaged, tachypnoea

Question 15

Grading of AEoA…

Answer 15

PEFR
Moderate: 75-50%
Severe: 50-30%, RR >25/min, HR> 100/min, can’t finish sentences
Threatening: <33%, stats <92%, CHEST criteria

Question 16

What is the CHEST criteria?

Answer 16

Cyanosis 
Hypotension 
Exhausted 
Silent chest
Tachycardic arrhythmias

Question 17

Treatment of AEofA

Answer 17

Moderate: 100% O2, nebulised SAMA/SABA, CS (oral: prednisolone, IV: hydrocortisone)
Severe: O2, IV SABA, & ^
Threatening: intubation, IV Magnesium Sulphate Infusion

Question 18

Prevalence of COPD…

Answer 18

10-20% of smokers develop COPD, dec in prevalence

Question 19

Class of COPD…

Answer 19

chronic & acute exacerbation of COPD (AEoCOPD)

Question 20

What is COPD…

Answer 20

chronic bronchitis and emphysema

Question 21

What is Chronic bronchitis and how does it occur?

Answer 21

Inflammation of bronchi

• inflammation of airways resulting in ulceration & fibrosis of airways narrowing them
• also inc in mucus secreting goblet cells resulting in mucus hyper secretion and blockage of airways (COPD has dysfunctional mucociliary escalator)

Question 22

What is emphysema and how does it occur?

Answer 22

Damaged alveoli

• abnormal permanent enlargement of alveoli due to destruction of their wall causing impaired gas exchange
• No bronchial support due to bronchitis so loss of lung recoil so small airways collapse and rapid closure of airways during expiration

Question 23

What are the main points for the pathophysiology of COPD?

Answer 23

inflammation & scarring, loss of lung elasticity, inc mucus secretion= airway narrowing
air trapping= hyperinflation= inc work of breathing

Question 24

COPD triggers…

Answer 24

smoking, long term exposure to toxins, not using inhaler properly

Question 25

COPD presentation…

Answer 25

breathlessness worsening with time, productive cough, frequent exacerbations, crackles, reduced breath sounds

Question 26

What is the COPD cascade?

Answer 26

fixed airway obstruction> impaired gas exchange> respiratory failure (inc CO2)> pulmonary HT> right ventricular hypertrophy (due inc work of breathing)> death

Question 27

COPD ix…

Answer 27

PFTs (FEV1:FVC ratio dec, PEFR low)
Imaging: cxr (flattened abdomen/hyperinflation), HRCT
ABGs: hypoxia/hypercapnia

Question 28

COPD Tx…

Answer 28

smoking cessation!!

1. SABA
2. LABA
3. combo LABA & LAMA/SAMA
4. step 3 + theophylline & inhaled corticosteroids

Question 29

What is COPD treatment expressed as?

Answer 29

Palliative as no possibility of resolution

Question 30

Causes of AEoCOPD?

Answer 30

Viral/ bacterial infection

Question 31

Ix for AEoCOPD?

Answer 31

ABGs (high bicarbonate)

Question 32

Tx for AEoCOPD?

Answer 32

Home: regular inhalers, oral prednisolone
Hospital: nebulised SABA & SAMA, prednisolone, antibis, 24-28% O2 (monitor PaCO2- can’t rise above 7kPa)
Severe: intubation

Question 33

True/False:

Asthma-COPD Overlap can be identified by COPD patient with eosinophilia >4%?

Answer 33

True