Asthma Flashcards by E Thomas

What is asthma?

A chronic inflammatory condition of the airway

Recurrent episodes of dyspnoea, cough and wheeze caused by airway obstruction

How well did you know this?

Not at all

Perfectly

What are the 3 characteristics/features of asthma?

Airflow limitation

Airway hyper-responsiveness to stimuli

Inflammation of the bronchi

How well did you know this?

Not at all

Perfectly

Is the airway obstruction in asthma reversible?

Yes, usually

How well did you know this?

Not at all

Perfectly

How is asthma classified?

Two categories.

Extrinsic: atopic
- allergens can be identified that are triggering the asthma

Intrinsic:

no definite external cause
many of these patients are atopic however

How well did you know this?

Not at all

Perfectly

When do extrinsic and intrinsic asthma patients usually present?

Extrinsic: childhood

Intrinsic: middle age

How well did you know this?

Not at all

Perfectly

Is there a genetic influence in asthma?

If so, which genes?

Yes

Often in genes involved in sensing pathogens

How well did you know this?

Not at all

Perfectly

What is atopy?

Syndrome where people develop IgE antibodies against common environmental antigens such as dust, pollen

Atopic people have one or more of:

Asthma
Eczema
Hayfever

How well did you know this?

Not at all

Perfectly

What 3 features cause airway narrowing in asthma?

Bronchial muscle contraction triggered by stimuli
Mucosal swelling and inflammation
Increased mucus production

How well did you know this?

Not at all

Perfectly

In an asthma attack it is harder for the person to breathe in than to breathe out.

True or false?

False

It is harder for the person to breathe out that breathe in
Resulting in hyperinflation of the lung

How well did you know this?

Not at all

Perfectly

How does the lung become hyper-inflated? And what happens when this happens?

In an acute asthma attack it is harder for the person to breathe in than out so the lungs become over filled.

No new air can get in or out so the blood does not receive enough oxygen

How well did you know this?

Not at all

Perfectly

What happens to the smooth muscle in the airways in asthma?

Inappropriate and excessive contraction, constricting the airways

Hypertrophy and proliferation of the smooth muscle cells, making the airways narrower

How well did you know this?

Not at all

Perfectly

What happens to the epithelial cells in the airways in asthma?

Metaplasia

Loss of ciliated columnar cells

An increase in the number of goblet cells

Increased basement membrane thickening

How well did you know this?

Not at all

Perfectly

What do goblet cells do?

Secrete mucus

How well did you know this?

Not at all

Perfectly

What is the role of antigen presenting cells (dendritic cells) in asthma?

They digest antigens of the allergen and present it to the lymphocytes which then cause inflammation

How well did you know this?

Not at all

Perfectly

When the lymphocytes have been triggered by being presented with an antigen, what do they do?

They release cytokines (interleukins mainly) which activate and summon mast cells and eosinophils

These continue the immune response causing inflammation

How well did you know this?

Not at all

Perfectly

What is the progression from encountering some pollen to developing asthma?

Inhale pollen

APCs present antigen to lymphocytes

Immune response occurs

Memory response is formed to the allergen, mediated by IgE

Immune system is now sensitised to the antigen

Everytime the person inhales pollen with this antigen again an immune response will occur

How well did you know this?

Not at all

Perfectly

What is the role of mast cells in asthma?

They are summoned to the site by lymphocytes (that had been activated by APCs)

Antibodies produced by B cell bind to the mast cells and cause them to degranulate

When mast cells degranulate they release inflammatory mediators such as cytokines and histamine

How well did you know this?

Not at all

Perfectly

What is the role of B cells in asthma?

They produce antibodies against the antigen

Theses then go on to activate mast cells to degranulate

How well did you know this?

Not at all

Perfectly

What does histamine do?

Increases the permeability of the capillaries to white blood cells and some proteins

This allows them to engage with pathogen/allergen in the affected tissues

Causes an inflammatory response

How well did you know this?

Not at all

Perfectly

What is eosinophilic asthma?

A type of asthma that involves eosinophils

Too many eosinophils are produced in the bone marrow

Too many eosinophils are recruited to the airways

How well did you know this?

Not at all

Perfectly

In eosinophilic asthma, what causes greater numbers of eosinophils to be produced in the bone marrow?

Interleukin 5

In eosinophilic asthma, what causes greater numbers of eosinophils to be recruited to the airways?

Chemokines

Prostaglandin 2

What is the role of eosinophils in asthma?

They contribute to airway remodelling and tissue damage

What is non-eosinophilic asthma?

No eosinophils are involved

Could be neutrophils instead

What are the phenotypes of asthma?

Eosinophilic Non-eosinophilic

List some causes of asthma attacks?

``` Cold air Exercise Emotion Allergens Infection (especially viral) Smoking Pollution NSAIDs B-blockers ```

How do asthma patients present?

Intermittent symptoms ``` Wheeze Cough SOB Chest tightness Sputum production ```

When are asthma patients' symptoms usually worse?

At night, usually about 4am

What are the 3 Royal College of Physicians questions to ask an asthma patient?

Any recent nocturnal waking? Usual asthma symptoms in the day? Interference with activities of daily living

What should you ask an asthma patient during a GP consultation?

Age of onset Did they have respiratory problems in childhood? Do they have signs of atopy: eczema, Hayfever Diurnal variation: worse in early hours of morning? Disturbed sleep Exercise tolerance What is their environment? Any pets, dusty carpet, feather pillows What is their job? Any allergens there, and do symptoms reduce when they are not at work? Family history

What are the signs of chronic asthma?

Tachypnoea Audible wheeze (polyphonic) Hyper-inflated chest Reduced air entry

What are the signs of a severe asthma attack?

Inability to complete sentences Pulse over 110bpm Resps over 25/min Peak flow 33-50% of predicted

What are the signs of a life threatening attack? What about near fatal?

Peak flow < 33% SpO2 < 92% PaO2 < 8kPa ``` Silent chest Reduced GCS Exhaustion = poor resp effort Cyanosis Hypotension ``` Near fatal = PaCO2 raised

What are the signs of a moderate asthma attack?

Peak flow over 50% of predicted No signs of severe asthma

How do you distinguish asthma from COPD?

COPD: Later onset and usually smoking related Relentless, progressive SOB + wheeze Less diurnal and day-to-day variation

Investigations for asthma.

Blood: eosinophils, O2 + CO2 stats Tests for atopy: skin prick tests CXR: exclude infection or pneumothorax Oxygen saturations Lung function tests: - Peak flow - Spirometry - (Response to a challenge agent) - Reversibility testing

What information can you get from spirometry?

FEV1 + FVC

What is FEV1?

Forced expiratory volume in 1 second

What is FVC?

Forced vital capacity: total amount of air exhaled during FEV test (all 3 seconds of exhalation)

What challenge agents are used in the response to a challenge agent test?

Mannitol: a bronchial irritant Methacholine: a bronchoconstrictor

What is a response to challenge agent test? | What does it help diagnose

Airways are irritated and you watch what happens to the person Helps diagnose exercise triggered asthma

What is reversibility testing?

Looks to see if there is an increase in lung capacity with bronchodilators or anti-inflammatory treatment

What is the differential diagnosis of wheeze, SOB, cough, etc.

Pulmonary oedema COPD Airway obstruction: tumour, foreign body Pneumothorax Pulmonary embolism Bronchiectasis

Which asthmatics are at risk of death?

Those on at least 3 classes of treatment Recent admission/frequent hospital attendance Previous near fatal disease Brittle asthma Psychosocial factors

What is Brittle asthma?

Type of asthma where they get recurrent, severe attacks

Treatment of chronic asthma?

Avoid triggers Use peak flow meter every day Educate in case of emergency Step up + down drug treatment: 1. SABA 2. SABA + LD ICS 3. SABA + LD ICS + LTRA 4. SABA + LD ICS + (LTRA if helpful) + LABA 5. SABA + (LTRA) + MART (with LD ICS) 6. SABA + (LTRA) + MART (with MD ICS) 7. SABA + (LTRA) + HD ICS + LAMA/theophylline + REFER

Which oral steroid is usually used?

Prednisolone

Which inhaled steroid is usually used?

Beclometasone

Management of an acute asthma attack.

Salbutamol nebulised with oxygen Prednisolone Monitor O2 stats, heart and resp rate Admit to ICE/HDU if in need of ventilation

What is the red-flag sign that you need to quickly admit to ITU/HDU and ventilate the patient?

Raised CO2 levels