Lecture 12 - Asthma Flashcards

1
Q

What is asthma?

A

The chronic inflammation of the airways causing REVERSIBLE airway obstruction

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2
Q

What are the 4 main symptoms associated with asthma?

A

Wheeze
Cough
Chest tightness
Breathlessness

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3
Q

Why can bronchiospasm occur in patients with asthma?

A

The patients have an increased airway responsiveness to stimuli, if stimuli occurs bronchoconstriction happens

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4
Q

What is meant by asthma exacerbation?

A

When there are periods of increased symptoms

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5
Q

Why is it thought that asthma is more prevalent in high income countries?

A

Better access to health care
Better diagnostic processes
Different climates (colder?)
More dust/air pollutants?

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6
Q

What is the pathophysiology of the airways in asthma?

During normal period:
During an asthma attack/exacerbation:

A

Inflammation and thickening of the smooth muscle and thickening of the epithelial layer which narrows the air way

In an attack the smooth muscle constricts (Bronchoconstriction) which significantly narrows the airway

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7
Q

What increases your risk of having asthma?

A

Genetic susceptibility (Mainly inherited from Mothers side)

Atopy

Sensitisation to an allergen

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8
Q

What are the 3 atopic conditions?

A

Eczema
Hay fever
Asthma

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9
Q

What is the triad of things that occur in the airways that all contribute to each other?

A

Airway inflammation
Airway hyper responsiveness
Airway remodelling

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10
Q

What are the 2 phases in the immune response in asthma?

A

Immediate response Type I hypersensitivity

Late phase response Type IV hypersensitivity

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11
Q

What cells are involved in the Type I hypersensitivity stage/sensitisation stage of asthma?

A

APC (like a macrophage)
Th2 (T-Helper cell 2)
B cells
Plasma cells
Mast cells or basophils

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12
Q

What is the end result in the Type I hypersensitivity phase?

A

Bronchoconstriction

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13
Q

Describe what happens in the Type I hypersensitivity stage of asthma:

A

First exposure to allergen
Allergen encounters APC (phagocytosed) and its antigen displayed on APC

Antigen of allergen activates Th2
Th2 activates B cell to stimulate plasma cell to produce IgE to that allergen

IgE then taken up by the inflammatory mast cells and basophils

When the allergen is reintroduced from the body, the allergen binds to the IgE now on the mast cells, this leads to mast cell degranulation leading to substances being released that cause bronchoconstriction

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14
Q

What is released by the degranulation of the mast cells in Type I hypersensitivity in asthma that leads to bronchoconstriction?

A

Histamine
Leucotrienes
Other inflammatory mediators

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15
Q

What are the 2 main types of asthma?

A

Eosinophilic/allergy asthma

Non allergic eosinophilic inflammation

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16
Q

What is the main interleukin produced that stimulates eosinophilic activity?

A

IL-5

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17
Q

What is the process that occurs in Eosinophilic asthma (atopic) in Type IV hypersensitivity?

A

Allergens in bronchiole
APC
T cell activates B-cells(Type I hypersensitivity)

T cell makes IL-5 which affects eosinophils increasing bone marrow production nd causing them to migrate to the airways

In the airways the eosinophils produce cytokines and other inflammatory mediators maintaining the inflammation

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18
Q

What is the key difference between eosinophilic asthma and non-allergic eosinophilic inflammation/asthma?

A

Eosinophilic asthma involves activation of Th2

Non-allergic eosinophilic inflammation/asthma doesn’t involve Th2 and doesn’t involve allergens

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19
Q

What is usually the trigger in the bronchioles leading to eosinophils moving into the airways in no-allergic eosinophilic inflammation?

A

Pollutants
Microbes

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20
Q

What is meant by the airways being hyper responsive in asthma?

A

The inflammation makes the airway more reactive meaning stimuli that are non allergen can trigger bronchoconstriction

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21
Q

What are some examples of stimuli that may trigger bronchospasms in asthma/trigger asthma?

A

Allergens
Dust
Car fumes
Cigarette smoke
Cold air
Exercise
Strong smells
Infection
Drugs (NSAIDs, beta blockers)
Emotional stress

22
Q

What airway remodelling can take place in asthma?

(Chronic inflammation of the airways)

A

Thickening and constriction of smooth muscle

Mucus hypersectrion and impaired mucus clearance due to cilia lost

Increased eosinophils and/or neutrophils in lumen

Sub epithelial inflammation and fibrosis

23
Q

What are some common symptoms/history’s of asthma patients?

A

Dry cough
Worse at night
Chest tightness
Wheeze
Breathlessness
History of Atopy
Family history

24
Q

What are some atopic features that may present with asthma?

A

Eczema
Rhinitis
Nasal polyps

25
Q

What is rhinitis?

A

The irritation of the nose often due to allergens

26
Q

When doing examinations how do you diagnose asthma?

A

You have to rule out other conditions

27
Q

How do you diagnose a patient with asthma who has a high probability of asthma?

A

Give inhaled steroids (anti inflammatories)
If all the symptoms resolve you diagnose with asthma

28
Q

What investigations are done if you suspect theres an intermediate probability of a patient having asthma?

A

Do peak flow rate
Spirometry

Then access bronchodilator reversibility

29
Q

What values does spirometry use?

A

FEV1
FVC

30
Q

What is FEV1?

A

The amount of air that an be forcefully exhaled in 1 second

31
Q

What is FVC?

A

The max amount of air that can be moved into or out of the lungs in 1 breath

32
Q

What can you get the patient to do at home if you’re unsure if they have asthma?

A

Get them to measure their peak flow twice per day for 4 weeks

Then you see the variability % between their best and worst reading

If variability > 20% then likely asthma

33
Q

If an asthma patient did spirometry, what would you expect their FEV1: FVC ratio to be?

A

Less than 70%

34
Q

How much would you expect the FEV1:FVC to improve by if a patient has asthma if you give them bronchodilators?

A

12% or more improvement in FEV1:FVC ratio

35
Q

How do you manage asthma patients?

A

Patient education (taking inhalers properly)

Trigger avoidance

Vaccines (reduce infection risk and so exacerbation)

Medications

36
Q

What medications are given for asthmatics?

A

Inhalers
Some oral and injectable meds as additional treatment in some patients

Stepwise approach

37
Q

What are the 3 diferent coloured inhalers?

A

Blue
Brown
Pink

38
Q

What is the function of the blue inhaler?

A

Brochodilator
(Short acting reliever)

39
Q

What is the function of the brown inhaler?

A

Anti inflammatory (steroid) inhaler

Reduces damage to the airway long term

40
Q

What is the function of the pink inhaler?

A

Combined bronchodilator and steroid/anti inflammatory inhaler

(Basically blue+brown inhaler)

41
Q

What type of drug is a bronchodilator?

What receptors does this target?

A

Beta agonist

B2 in lungs

42
Q

Why is it very concerning if a patient who is having an asthmatic attack/exacerbation has a normal pCO2 despite having low pO2?

A

They are becoming exhausted so their ability to hyperventilate is getting worse
This is allowing the CO2 levels in the blood to build up which will lead to hypercapnia

43
Q

How many you treat a patient with asthma exacerbation?

A

Salbutamol by nebuliser
+
Oral steroids

44
Q

What are some reassuring signs seen when examining an asthma patient?

A

Normal resp rate
Normal Heart rate
Normal O2 sats
Normal breathing pattern
Wheeze
Alert
Speaking full sentences

45
Q

What are some concerning signs seen when examining an asthma patient?

A

Tachypnoea
Tachycardia
Hypoxia
Unable to speak full sentences
Accessory muscle use
Silent chest
Altered conscious level

46
Q

What oxygen sats do you aim to get for asthma exacerbation?

A

94-98

47
Q

What steroids can be given if its a serious asthma exacerbation?

A

Magnesium sulphate IV
Aminophylline IV

48
Q

What conditions does asthma mimic or can be associated with asthma?

A

Psychosocial factors: anxiety, depression, panic disorder

Inducible laryngeal obstruction/vocal cord dysfunction

Breathing Pattern Disorder

49
Q

Why are asthma symptoms worse at night?

A

There’s more parasympathetic outflow at night meaning theres more vasoconstriction leading to more constriction of airways

More muscles relax so increased resistance in airways

50
Q

How would you be able to tell the difference between asthma or COPD using spirometry?

A

Asthma - when given bronchodilators theres a 12% or more improvement in the FEV1:FVC ratio

COPD - when given bronchodilators there’s less than a 12% improvement in FEV1:FVC since COPD is irreversible asthma is reversible