Asthma Flashcards
What is the basic cellular underpinning of asthma?
Hyper-responsive airways disease
(type 1 hypersensitivity - IgE mediated)
Exposure - Th2 response, mast cells become sensitised to antigen, IgE binds to Fc epsilon receptors on mast surface
Second + exposure - mast cell degranulation, release mediators such as histamine (broncho constrict, vasodilate), PGD2 (vascperm inc), LTA4 (inc mucus), and pro-inflammatory cytokines TNF-A, IL4, IL12 etc
Later inflammatory response: eosinophils, basophils, Th2 cells. Proteases damage lung tissue. Leads to destruction of epithelium chronic inflammatory changes and risk of airway remodelling.
What are the key gross changes in the pathophysiology of asthma?
Reduced airway diameter due to airway inflammation and production of excess mucous.
Bronchoconstriction
Airway oedema.
Difficult to exhale
Define asthma
Chronic inflammatory airway disease characterised by: chronic bronchial inflammation, airway hyperresponsiveness and obstructive air-flow limitation
What are the key distinctive features of asthma?
Diurnal variability - PEFR variation >20% - worse at night or early morning.
Usually presents in childhood, however can develop in adults.
What are the different forms of asthma?
Eosinophilic
Non-eosinophilic
Occupational
Irritant induced
Exercise-induced bronchospasm.
What are the typical symptoms of asthma?
Cough (nocturnal /dry)
Wheeze (widespread polyphonic wheeze)
Chest tightness
SOB - intermittent, worse at night/monring/trigger
Variable expiratory airflow limitation - vary in time and intensity
Triggerd by exercise, allergen, irritant, changes in weather, viral respiratory infection
May resolve spontaneously or in response to medication - may be absent for weeks or months at a time
What is meant by acute asthma exacerbation?
Onset of severe asthma symptoms, can be life-threatening.
What can cause a wheeze sound in the lungs?
Airway obstruction - narrowed airway - results in a wheeze
Asthma - reversible
COPD - fixed
Upper airway obstruction (stridor)
Foreign body
Pulmonary edema (cardiac wheeze)
Eosinophilic vasculitis /EGPA / MPO-ANCA
Respiratory bronchiolotitis
What is important to do when taking a history from a potential asthmatic patient?
Characterise resp pathology - pattern of symptoms (variation, timing)
Explore trigger (pets, carpets, temp, occupational exposure, smoking)
Personal or family history of atopy
Assess severity of asthma - best expected and recent PEFR, treatment adherence, attendance to hospital with exacerbation/previous ICU
Normal SABA requirements
What may be found during respiratory examination of an asthmatic patient?
Around bedside - oxygen, inhaler, space, PEFR meter
Inspection - inc work of breathing, cyanosis, cough, audible wheeze
Peripheries - fine tremor (salbutamol), tachycardia, oral candidiasis (steroid inhaler use)
Chest - polyphonic expiratory wheeze.
What are some risk factors and triggers for asthma?
Irritant induced - chemical and perfumes - cause tissue damage and generate an immune response
Allergic/sensitized - classic, repeated trigger recongised as foreign (pets, pollen), should establish relationship between trigger and when asthma worse.
Family history - first degree relatives with atopic history
Prematurity and LWB
Medications - beta blockers and NSAIDs - exacerbate asthma.
What is meant by occupation asthma?
Types?
Symptoms improve when patient away from work
Onset >1yrs after starting work - time for sensitivity to develop
Sensitised induced (allergen response) or irritant induced (chemical cause local inflammation, immune response to inflamed tissue)
What is the diagnostic process behind asthma?
More than one variable wheeze, cough, breathlessness and chest tightness
pMH or FH of atopic conditions
FeNO - eosinophilic inflammation is 17yrs+, 40ppb+
Spirometry - obstructive (FEV1/FEV <70%)
Bronchodilator reversibility - 12% improvement
Variable PEFR - 20% variability after BD for 2-4w.
May also give a BHR test, IgE blood test, RAST test.
Describe the difference between obstructive and restrictive lung disease on spirometry.
Obstructive - FVC remains normal or slightly reduced, FEV1 reduced, FEV1/FVC <70
Restritive - FVC reduced, FEV1 reduces proportionately . FEV1/FVC ration remains around normal.
How do we assess the functional impact of asthma on a patient?
Number of SABA used per week/day
Number of days missed from school/work
Nocturnal symptoms
Any recent exacerbation?
Ever required hospital attendance?
Ever been to intensive care?
What safety netting should be provided to patients receiving community chronic asthma treatment?
Use of SABA >3x weekly - go to GP
<4hr gas between requirements for salbutamol - go to A&E
10 puffs of salbutamol without relief of symptoms - call 999
What conservative management is often recommended for asthmatics?
Smoking cessation/avoidance of triggers
PEFR diary
Regular annual asthma reviews (typically in GP annually) - presonalised asthma plan and inhlaer technique education
Vaccination - flu, covid-19,
What are some side effects of inhaled salbutamol ? (asthmatics)
Tachycardia
Tremor (fine)
When is the use of inhlaed corticosteroids indicated in asthmatics?
Nocturnal symptoms
Recent severe exacerbation
SABA use >3 times/week
What are the side effects of inhaled corticosteroid use? (asthmatic inhlaers)
Oral candida
What is the pharmacological treatment pathway for adult asthmatics?
- Newly diagnosed - SABA
- SABA only if infrequent, short lived wheeze, normal lung function
- ICS first line maintenance if symp 3>w, night waking, SABA use >3w
- Then offer LTRA
- Then offer combined LABA and ICS, review LTRA or consider inc ICS dose
- MART (budesonide and formoterol) regime and refer for specialist care.
Name the typical drug used for each class of inhaler/medication given in asthmatics?
SABA = salbutamol
ICS = inhaled budesonide, oral prednisolone
LABA = salmeterol
LTRA = montelukast
What are some common complications of asthma?
Exacerbations
Secondary Pneumothorax
What is an asthma exacerbation?
Infective of non-infective
Bronchospasm, mucosal thickening and mucous production
Narrows terminal airway = acute deterioation in breathlessness
Leads to hyperventilation until exacerbation resolves
At what severity is asthma considered moderate acute?
Increasing symptoms
PEF >50-75% best or predicted
No features of acute severe
At what point is asthma considered acute severe?
PEF 35-50% best or predicted
RR >25/min
HR >110bpm
Inability to complete sentences in one breath
At what point is asthma considered life-threatening?
Acute severe asthma with any one of the following:
PED <33% BEST or predicted
SpO2 <92%
PaO2 <8 kPa
Normal PaCo2
Altered conscious level /exhausation
Arrhythmia
Hypotension
Cyanosis
Silent chest
Poor respiratory effort
At what stage is asthma considered near fatal?
Raised PaCO2 and/or mechanical ventilation with raised inflation pressures.
What investigations should be done on an asthmatic?
Peak flow - severity
Observations - severity
Sputum culture - infective exacerbation
ECG - tachy/arryhtmia
FBC - eosinophils
CRP - inflammatory markers
ABG - respiratory alkalosis in moderate exacerbation, nor in life threating asthma, high in near fatal.
CXR - focal changes, pneumothorax
Spirometry - obstructive and reversibility pattern
What acute management should be used for asthmatics?
- oxygen - 15L non-rebreath
- Help
- Salbutamol - 2.5-5mg nebs
- Hydrocortisone - 100mg IV or prednisolone 40mg PO
- Ipatropium 500mg neb
- Theophylline (PDE5 inhibitor)- aminophylline infusion
- Magneisum sulphate 2g IV over 20mins
Escalate care - +/- antibiotics if infective exacerbation.
Before discharging an acute asthma admission what should be ensured?
Stable for 4hrs after exacerbation
Ensure PEFR returned to >75%
If infective exacerbation of asthma how long should steroid/abx be continued?
Pred for 5 days +/- antibitoics
In life threatening asthma/tiring asthmatic what additional support may be required in ICU?
BPAP
Intubation
ECMO
Due to loss of respiratory drive.
When is it not safe to send ana cute asthmatic home from ED?
Exacerbation whilst on course of steroids
History of poor compliance with treatment
History of depression/anxiety
History of severe/refractory asthma (previous ICU)
Pregnancy
Poor social circumstances.
What should be done at the annual review of an asthmatic?
Asthma control - spirometery or peak flow variability testing
Inhlaer technique
Risk factors
Discuss treatment options
Check/update asthma action plan
Assess asthma severity
May discuss smoking, exercise, healthy weight maintenance
What are the four key disease processes that occur in asthma?
Chronic bronchial inflammation
Airway hyper-responsiveness
Obstructive airflow limitation
Reversible
What type of hypersensitivity reaction is asthma?
Type 1
What are the several forms of bronchial asthma?
Occupational
Exercise induced
NSAID induced
Allergic
Thunderstorm
What is meant by brittle asthma?
Term to describe a severe type of asthma
Type 1 - uncontrolled - regularly use high doses of inhaled steroids but still have large changes in PEF and active symptoms
Type 2 - suddenly develop severe asthma attacks for no apparent reason despite having otherwise well-controlled asthma.
How do we assess the severity of asthma?
Best expected and recent PEFR
Adherence with treatment
Attendance to hospital with exacerbation/previous ICU admission
Normal requirement for SABA/whether this has changed.
What on examination can be a sign that an asthmatic is reliant on their medication?
Fine tremor due to salbutamol
Oral candidiasis due to oral steroids.
When using clinical judgment to determine the probability of an asthma diagnosis, what features should it be based on?
- Variable symptoms of wheeze, cough, breathlessness and chest tightness
- Personal/FH of atopic conditions
- Results of FeNO testing
- Results of objective tests including - spirometry, BDR, PEFV
- Results of a direct bronchial challenge test with histamine or methacholine (requires specialist)
What is asthma COPD overlap syndrome?
Clinical conditions characterised by peristent airflow limitation with several features usually associated with both asthma and COPD.
Increased reversibility, eosinophilic bronchial and systemic inflammation, and increased response to corticosteroids.
Who is asthma COPD overlap syndrome more common in?
- Smokers or ex-smokers with a history of childhood asthma
- Suspected to have a genetic polymorphism relationship.
- Long term exposure to pollutants such as occupational dust
- Allergen exposure
- Poorly controlled asthma
- Recurrent resp infections particularly in childhood
- Age - more in adulthood
- Female
How does Asthma COPD overlap syndrome present clinically?
Frequent exacerbations - often more severe than in COPD or asthma in isolation.
Severe dysponea
Cough
Wheezing and chest tightness
Poor health related quality of life
How does Asthma COPD overlap syndrome present on examination?
Prolonged expiration
Wheezing on auscultation
Hyperinflation of the chest
Use of accessory muscles for respiration including resp distress
Advanced - signs of cor pulmonae such as peripheral oedema and raised JVP
What is the typical pharmacological treatment for asthma COPD overlap syndrome?
Inhaled corticosteroids combined with LABA are the first line.
May then add on LAMA if remain symptomatic or frequent exacerbations
What co-morbidities are common in asthma COPD overlap syndrome?
Cardiovascular disease
Osteoporosis
Depression
Anxiety
GERD
What are the different theories around Asthma COPD Overlap Syndrome as a disease?
For reference not learning
