Respiratory: Asthma Flashcards
Define asthma
A disease that includes the symptoms of wheeze, cough and breathing difficulty together with reversible airway obstruction, airway inflammation and bronchial hyper responsiveness.
However, asthma is a heterogeneous and variable condition, frequently not all of the above are present in each individual.
Not everyone that wheezes has asthma. What other causes of wheeze are there?
Respiratory infections, especially viral - bronchiolitis, bronchiolitis obliterans
Airway abnormalities
- bronchiomalacia
- chronic lung disease of prematurity
Foreign body inhalation
What is viral induced wheeze?
A virus that triggers reversible narrowing in airways
Responds to asthma medication
Why can the diagnosis of asthma be difficult?
It is a variable condition - part of its characteristic
From what age can spirometry be typically done in children?
From 5 years old
What tests should be done (if old enough)?
Spirometry and bronchodilator reversibility test
Peak flow variability
To test for eosinophil inflammation or atopy: FeNO test, blood eosinophils, skin prick test for IgE
What symptoms are associated with asthma?
Wheeze Cough SOB Chest tightness Exercise induced cough/wheeze Nocturnal cough/wheeze
The symptoms tend to be…
Variable
Intermittent
Worse at night and early in morning
Provoked by triggers - pollen, dust, smoke, emotion, animal dander
Positive response to asthma therapy
Interval symptoms ie symptoms between acute exacerbation
What factors increase the risk of asthma?
Personal/family history of atopy Previous episode of bronchiolitis Low birth weight, prematurity Poor maternal control of asthma in pregnant women Bottle fed Exposure to passive smoking
What can be seen on examination?
Chest usually normal between attacks
Long standing asthma: hyperinflation, generalised wheeze, Harrison’s sulci
Evidence of eczema
In severe cases: growth restriction - plot growth each time
What are Harrison’s sulci?
Permanent indentation of the chest wall along the costal margins where the diaphragm inserts
What are features of a mild to moderate acute asthma presentation?
O2 more than 92% RR < 30 in over 5 RR < 40 under 5 No or minimal accessory muscle usage Feeding well, talking full sentences Wheeze (May need stethoscope to hear)
What are features of severe asthma?
O2 < 92% RR> 30 over 5 RR>40 under 5 Too breathless to feed or talk HR > 125 over 5 HR> 140 under 5 Use of accessory muscles Audible wheeze PEF 33-50% of best/predicted
What are features of life threatening asthma?
O2 <92% Silent chest Poor respiratory effort Altered consciousness - confused or drowsy Agitation Cyanosis PEF < 33% best or predicted
There should be a low threshold for admittance if…
Previous CICU/severe episode/rapid deterioration
Repeated ED attendance over last year
On high dose ICS
What is the airflow obstruction a result of?
Smooth muscle constriction
Mucous production
Bronchial inflammation
What does bronchial inflammation result from?
IgE dependent release of mediators from mast cells e.g histamine, tryptase, prostaglandins
These mediators cause further bronchoconstriction and inflammation
What can mucus plugs do?
Block small airways and further limit airflow
What is airway hyper responsiveness?
Exaggerated constriction in response to variety of stimuli
- sudden onset of symptoms
Although asthma is characteristically described as having reversible airflow limitation, what can happen over time?
Airway remodelling can occur - the airway limitation only partially reversible.
Ongoing inflammation can cause permanent structural changes e.g thickening of membrane, fibrosis, smooth muscle cell hypertrophy and hypersecretion
Describe the cough
Dry and non productive
Nocturnal
Describe the wheeze
Typically expiratory, but if severe can be biphasic
Usually polyphonic (variable pitch)
Can usually be heard w/o stethoscope
In severe asthma wheeze may disappear and no airway sounds = silent chest
What signs suggest increased work of breathing?
Tachypnoea Use of accessory muscles Intercostal, subcostal recessions Head bobbing Grunting Nasal flaring Sitting forward posture
Do children under 5 need investigations?
NICE recommends treating symptoms based on a clinical diagnosis without investigation and then carry out testing if symptoms still present at 5
What is suggestive of an obstructive airway disease?
FEV1:FVC less than 70%
In the bronchodilator reversibility rest, an improvement by what percentage in 5-16 year olds is suggestive of asthma?
> 12 %
If there is normal spirometry and negative bronchodilator reversibility, what test can be done?
Fraction of exhaled nitric oxide test
- level greater than 35 parts per billion is suggestive of asthma
If there is diagnostic uncertainty, what test can be done?
Monitoring peak flow variability for 2-4 weeks
Greater than 20% variability considered positive
After diagnosis PEF can be used as an indicator for treatment effect and marker of clinical improvement/deterioration
How is asthma managed in children <5?
1) SABA as reliever
If not controlled or new diagnosis with symptoms >= 3 /week or night time waking :
2) SABA plus 8 week trail of paediatric moderate dose ICS
- after 8w stop ICS and monitor symptoms
- if symptoms resolved and reoccurred in 4w restart the ICS at paediatric low dose as first line maintenance
- if symptoms resolved but reoccurred beyond 4 weeks repeat the 8w of paediatric moderate dose ICS
3) SABA+ paed low dose ICS+ LTRA
4) Stop the LTRA and refer to paediatric asthma specialist
How do LTRA work?
They oppose the effects of leukotrienes = inflammatory mediators
Leukotrienes promote bronchoconstriction, inflammation, microvascular permeability and mucus secretion
What is an example of a LTRA?
Montelukast
How is asthma managed in children between 5 and 16?
1) SABA as reliever
If not controlled with above, new diagnosis with 3 symptoms per week or night time waking:
2) SABA plus paediatric low dose ICS
3) SABA+paediatric low dose ICS + LTRA
4) SABA + paediatric low dose ICS + LABA
5) SABA + switch ICS/LABA for a maintenance reliever therapy (MART) regime - single inhaler contains low dose ICS and fast acting LABA
6) SABA+paediatric moderate dose ICS MART regime or change back to fixed dose of moderate ICS and separate LABA
7) SABA + either paediatric high dose ICS as part of fixed dose regime/MART or trial of additional drug s.g theophylline
What is MART?
A form of combined ICS and LABA in a single inhaler used for both daily maintenance and relief of symptoms as required.
The LABA component of MART should be fast acting e.g formoterol
What preventer treatment examples are there?
Beclomethasone dipropionate (clenil) Budesonide (pulmicort) Fluticasone propionate (flixotide)
What is seretide a combination of?
Salmeterol (LABA) and fluticasone (ICS)
What is symbicort a combination of?
Formoterol and budesonide
What is fostair a combination of?
BDP and salmeterol
How is a mild/ moderate asthma exacerbation managed?
Up to 10 puff ps of salbutamol via inhaler and spacer
Reassess after 30 mins
If no improvement: give 10 puffs every 10-20mins up to 3 times
Consider oral steroids (usually dexamethasone) - no evidence that steroids are effective in mild asthma
How is severe asthma managed?
High flow oxygen via reservoir mask
Salbutamol and ipratropium bromide nebulisers every 20 minutes (inhaler if saturations over 92% OA)
Oral steroids or hydrocortisone IV
How is life threatening asthma managed?
Move to resus
High flow O2
IV salbutamol
IV hydrocortisone
- IV magnesium sulphate as short term measure
- NIV e.g CPAP can help if IV salbutamol not helping
What is ipratropium bromide?
An anticholinergic bronchodilator (green inhaler)
If a child is being discharged after asthma exacerbation, what discharge planning should be done?
Check inhaler technique
Update personal written asthma action plan
Ask family to make appointment with GP within 48 hours
