Asthma

Question 1

what immune cell mediates asthma?

Answer 1

CD4 mediated, and the lungs will show an eosinophil infiltrate

Question 2

what are the 3 main characteristics of asthma?

Answer 2

Airflow limitation
Airway hyper-responsiveness
Inflammation of the bronchi

Question 3

in asthma, inflammation of the bronchi results in

Answer 3

infiltration by eosinophils, T cells and mast cells. Associated plasma exudate, oedema, smooth muscle hypertrophy, mucus plugging and epithelial damage

Question 4

asthma is

Answer 4

long term inflammation of the lungs

Question 5

What is the inflammatory process of asthma?

Answer 5

CD4 differentiates T helper cells
Excessive reaction by TH2 cells
Environmental triggers are picked up by dendritic cells and presented to TH2 cells
Produce cytokines like IL-5 and IL-4

Question 6

what does IL-4 cause in asthma?

Answer 6

causes B cells to become plasma cells, which secrete IgE which coat mast cells (and basophils?) – produce histamines, leukotrienes, prostaglandins

Question 7

what does IL-5 cause in asthma

Answer 7

produce eosinophils which promote immune response by producing more cytokines and leukotrienes

Question 8

what type of hypersensitivity reaction is asthma?

Answer 8

Type 1 - IgE anitbodies produced

Question 9

What are the airway affects of the inflammation?

Answer 9

Minutes after allergen exposure:
Smooth muscle around bronchioles spams and increased mucous secretion
= narrows airways = difficult to breathe = obstructive
Also:
Increased vascular permeability and
Recruitment of immune cells - Eosinophils that release chemical mediators that physically damage endothelium of the lung

Question 10

what is the process behind irreversible damage in asthma?

Answer 10

Oedema, scarring and fibrosis build up
Thickens epithelial basement membrane
Permanently reduces airway diameter
Epithelial cells lose columnar cilated cells and these are replaced with over active mucous secreting cells

Question 11

what are the other intrinsic types of asthma?

Answer 11

non-atopic - recurrent viral resp infections
aspirin - increased leukotrienes and decreased prostaglandins
occupational - type 1 + 4, allergin can bind directly to T
food

Question 12

What are the 2 types of asthma?

Answer 12

Intrinsic and Extrinsic

Question 13

what is intrinsic asthma

Answer 13

asthma with no causatory factor

Question 14

when is the common onset of intrinsic asthma?

Answer 14

late onset - middle age

Question 15

what is extrinsic asthma

Answer 15

asthma with definite external causes

Question 16

what are the 2 types of extrinsic asthma?

Answer 16

atopic and non-atopic

Question 17

what are the causes of atopic asthma?

Answer 17

genetic - ADAM33, PHF11

environmental - hygiene hypothesis

Question 18

how is the ADAM33 gene linked to asthma?

Answer 18

airwar hyper-responsiveness and airway remodelling
is responsible for the release of factors by eosinophils. Some of these factors include MBP (major basic protein), ECP (eosinophil cationic protein) and other factors. These factors can cause remodelling of the epithelium, and stimulate growth of fibroblasts

Question 19

how is PHF11 linked with asthma?

Answer 19

increased IgE production

Question 20

what are common triggering symptoms of asthma?

Answer 20

Air Pollution – cigarettes, car exhausts
Allergens – dust, pet dander, cockroaches, mould
Medications – aspirin, beta blockers

Question 21

What are the common symptoms of asthma?

Answer 21

coughing, chest tightness, dyspnoea, wheezing, reduced air entry, sputum

Question 22

what are the features of wheeze in asthma?

Answer 22

Expiration
Audible
Polyphronic
Widespread

Question 23

what are the features of sputum in asthma?

Answer 23

curschman spiral (spiral shaped mucous plugs from small bronchi)
charcot-leyden crytsals – needle shaped, from breakdown of eosinophils

Question 24

what other aspects of an asthma history should you ask?

Answer 24

Precipitants, Diurnal variation, Exercise, Disturbed sleep, Acid reflux, Other atopic disease, The home, Job, Days per week of work or school

Question 25

what are the 2 main diagnostic features of asthma?

Answer 25

Diurnal variation of 20% on>3d a week for 2 weeks ↓ FEV1/FVC = <75%, obstructive pattern (Usually >15% improvement in FEV1 following B2 agonists or steroid trial)

Question 26

Other diagnostic tests for asthma

Answer 26

``` PEFR monitoring NO – raised in asthma Exercise Tests Trial of Corticosteroids Blood and Sputum tests CXR – hyperinflation Skin prick tests may help identify allergens Histamine or methacholine challenge Aspergillus serology ```

Question 27

what is the treatment of an asthma attack

Answer 27

Start on 100% O2 (non-rebreathing mask) with the patient sat upright in bed Give 5mg salbutamol with 0.5mg ipratropium bromide via nebulizer on 100% O2 Give hydrocortisone 100mg IV or 50mg prednisolone orally. Give both if very unwell Do CXR to exclude pneumothorax

Question 28

what is the management of a non resolved asthma attack

Answer 28

Inform ITU and seniors Give magnesium sulphate 1.2-2g IV over 20 minutes Change the nebulized salbutamol every 15 minutes, or give 10mg continuously per hour. Only give more ipratropium every 4-6 hours Repeat PEF every 15-30 minutes to assess the situation

Question 29

Pharmacological management of asthma

Answer 29

Short acting β2agonists as required (unless using MART) – consider moving up if using three doses a week or more Low-dose ICS Add inhaled LABA to low-dose ICS (fixed dose or MART) Increasing ICS to medium dose or Adding LTRA If no response to LABA, consider stopping LABA Refer to specialist care

Question 30

Step 1: Mild intermittent and exercise induced asthma is defined as

Answer 30

 Symptoms ≤2 times a week  Asymptomatic and normal peak expiratory flow (PEF) between attacks  Attacks are brief with varying intensity  Night-time symptoms ≤2 times a month  Forced expiratory flow at 1 second (FEV1) or PEF ≥80% of predicted  PEF variability <20%.

Question 31

Step 2: mild persistent asthma is defined as

Answer 31

```  Symptoms >2 times a week but <1 time a day  Exacerbations may affect activity  Night-time symptoms >2 times a month  FEV1 ≥80% of predicted  PEF variability between 20% and 30%. ```

Question 32

Step 3: moderate persistent asthma is defined as

Answer 32

 Daily symptoms  Use of short-acting beta agonists daily  Attacks affect activity  Exacerbations ≥2 times a week and may last for days  Night-time symptoms >1 time a week  FEV1 greater than 60% to less than 80% of predicted  PEF variability >30%.

Question 33

step 4-6 severe persistent asthma is defined as

Answer 33

```  Continual symptoms  Limited physical activity  Frequent exacerbations  Frequent night-time symptoms  FEV1 ≤60% of predicted  PEF variability >60%. ```

Question 34

what are the differential diagnosis of asthma?

Answer 34

pulmonary oedema, COPD, large airway obstruction, SVC obstruction, pneumothorax, PE, bronchiectasis, obliterative bronchiolitis

Question 35

what are the "bonus points" treatment for asthma attack?

Answer 35

``` ensure good analgesia take time to reassure patient check inhaler technique PEFR check compliance ```

Question 36

which type of respiratory failure is common in asthma attacks?

Answer 36

type 2 respiratory failure (low CO2, high O2)

Question 37

Treatment of Life threatening asthma

Answer 37

``` recognise call for help high flow o2 back to back inhalers IV hydrocortisone IV magnesium IV aminophylline infusion ECG ```