Asthma

Question 1

What are the 3 features of asthma?

Answer 1

reversible airway obstruction
airway inflammation
bronchial hypersensitivity and constriction

Question 2

What 3 factors contribute to airway obstruction?

Answer 2

1 bronchial muscle constriction caused by stimuli
2 swelling and inflammation caused by mast and basal cell degranulation and histamine/other inflammatory markers release
3 increase mucus production

Question 3

What is the difference between extrinsic and extrinsic asthma?

Answer 3

extrinsic asthma- early onset (childhood) due to a known cause
intrinsic asthma- late onset due to an unknown cause

Question 4

What is sensitisation?

Answer 4

exposure to an allergen which results in the development of an immune response

Question 5

what are the classical symptoms of asthma?

Answer 5

cough (worse at night)
wheeze
SOB
chest tightness

Question 6

What type of reaction is allergic asthma?

Answer 6

Type 1 hypersensitivity reaction

Question 7

describe the early phase of asthma

Answer 7

sensitisation–>IgE release
IgE binds to mast cells–>degranulation and histamine release
smooth muscle contraction, bronchoconstriction and inflammation–>airway obstruction
Tcells cause cellular infiltration into bronchial walls
afferent nerve activation leads to mucus hypersecretion
eosinophils migrate to mucosa and release leukotrienes which constrict the airways.

Question 8

describe the late phase of asthma?

Answer 8

production of chemotaxis (leukotrienes, platelet activating factor) attracts leukocytes–>inflammation and upper airway hypersensitivity

Question 9

Explain how asthma can cause chronic airway obstruction?

Answer 9

repeated exposure to triggering antigens can lead to airway remodelling.
fibrous tissue is laid down leading to permanent airway obstruction
steroids can prevent chronic remodelling

Question 10

What are the respiratory accessory muscles?

Answer 10

sternocleidomastoid
pectorals (major and minor)

Question 11

Outline 4 signs of severe asthma

Answer 11

RR>25
HR>110
can’t talk in full sentences
PFR<50% of expected

Question 12

Life threatening asthma- criteria

Answer 12

33 92 CHEST- if any of these call anaesthetists and ICU
PFR<33% expected
sats <92%
Cyanosis
Hypotension
Exhausted
Silent chest
Tachy or bradycardia

Question 13

What are some triggers of asthma

Answer 13

cold air, exercise, emotion, allergens (house dustmites, pollen, fur), infection, pollution, NSAIDs, B blockers, smoking or passive smoking

Question 14

True/False- Atopic individuals will develop asthma at lower levels of exposure

Answer 14

True

Question 15

Why does systolic BP decrease on inspiration and pulse go up slightly?

Answer 15

inspiration makes the intrathoracic pressure more negative relative to atmospheric pressure.
negative pressure increases venous return to the heart due to the increase in pulmonary vasculature volume.- lots of blood flow to right side of the heart and the left side of the heart is slightly more compressed –> decreased stroke vol –>low systolic BP–>increase HR (pulse)

Question 16

What sort of blood gas abnormalities would you expect in asthma?

Answer 16

high PaCO2- >6kPa
severe hypoxaemia (low O2) <8kPa despite O2 treatment
low pH

Question 17

Outline the management of an acute asthma attack (7 steps)

Answer 17

1. ABC approach
2. 100% O2 non rebreathe mask
3. Hx, Ex, diagnosis asthma
4. salbutamol 5mg neb
5. ipratropium bromide 500 micrograms neb
6. steroid hydrocortisone 100mg IV if severe or 40-50 if moderate
7. theophylline (life threatening)