Respiratory - Asthma Flashcards
What is asthma?
Chronic inflammatory condition that causes bronchoconstriction and therefore obstruction to airflow
Type 1 hypersensitivity
Asthma triggers
Infection Night-time/early morning Exercise Animals Cold/damp Dust Strong emotions
Typical presentation of asthma
Episodic symptoms
Diurnal variability. Typically worse at night.
Dry cough with wheeze and shortness of breath
A history of other atopic conditions such as eczema, hayfever and food allergies
Family history
Bilateral widespread “polyphonic” wheeze heard by a healthcare professional
Features that suggest an alternative diagnosis over asthma
No response to treatment
Unilateral wheeze
Isolated or productive cough
Diagnosis of asthma
Symptoms of asthma plus 2 objective tests from these:
FENO (fractional exhaled nitric oxide) - In steroid-naive adults, a FeNO level of 40 parts per billion (ppb) or higher is considered a positive result. (35ppb in children)
Spirometry with bronchodilator reversibility:
- an improvement in FEV1 of 12% or more, together with an increase in volume of at least 200 mL in response to beta-2 agonists or corticosteroids is regarded as a positive result.
- An improvement of greater than 400 mL in FEV1 is strongly suggestive of asthma.
- Normal spirometry when the person is asymptomatic does not rule out asthma
Peak flow variability
What may affect FENO results?
results of FeNO tests may be affected by empirical treatment with inhaled corticosteroids.
What FEV1/FVC ratio suggests obstructive picture e.g. asthma?
<0.7
What is counted as symptomatic asthma if the patient is on SABA? What should be done?
Use of SABA 3x/week or more
Asthma symptoms 3 times/week or more
Being woken at night with symptoms once per week or more
In this case start an ICS
What is the NICE step-wise regime for asthma control?
- SABA PRN for infrequent wheezy episodes.
- Add regular low dose ICS
- Add LTRA
- Add LABA - Continue the LABA only if the patient has a good response.
- Consider changing to a maintenance and reliever therapy (MART) regime.
- Increase the inhaled corticosteroid to a “moderate dose”.
- Consider increasing the inhaled corticosteroid dose to “high dose” or oral theophylline or an inhaled LAMA (e.g. tiotropium).
- Refer to a specialist.
After how long should the patient be reviewed and potentially step up in medication be done?
4-8 weeks after change in treatment
Also check inhaler technique at each appointment
How do the different classes of asthma medications work?
SABA - short acting beta2 adrenergic receptor antagonist - smooth muscle relaxation and therefore bronchodilation
ICS - e.g. beclometasone - reduce inflammation in the airway
LABA - e.g. salmeterol (same as SABA but longer-acting)
LTRA - e.g. montelukast (blocks the effects of leukotrienes - these are produced by the immune system and cause inflammation, bronchoconstriction and mucous secretion)
Theophylline - relaxing bronchial smooth muscle and reducing inflammation
Theophylline special considerations
Narrow therapeutic window so plasma theophylline needs to be measured
Done 5 days after starting treatment and 3 days after each dose changes.
MART therapy
Combination inhaler containing a low dose inhaled corticosteroid and a fast acting LABA.
This replaces all other inhalers and the patient uses this single inhaler both regularly as a “preventer” and also as a “reliever” when they have symptoms.
Other additional management for asthmatics
Yearly asthma review
Flu jab yearly
Advice on exercise and smoking cessation
Explaining inhaler technique
Check the expiry date of the medication
Hold the inhaler upright and remove the cap to check nothing is in the mouthpiece
Shake the inhaler
Sit upright or stand
Breathe out and then put your mouth around the inhaler with a tight seal
Breathe in slowly and steadily whilst pressing the canister once until lungs feel full
Hold breath for 10s or as long as you comfortably can
Breathe out
Wait 30s if need a second puff
SPACER DEVICES - wash with detergent and allow to air-dry. Replace once a year
ICS - rinse out mouth after use - to prevent oral thrush
If symptoms not responding after 10 puffs call 999
What is severe acute asthma exacerbation?
PF 33-50% best
HR >110bpm
RR >25/min
Inability to complete sentences in one breath
What is life-threatening acute asthma exacerbation?
PF <33% best Sats <92% Poor respiratory effort - exhaustion Silent chest Hypotension Cyanosis Altered consciousness
What is life-threatening acute asthma exacerbation?
PF <33% best Sats <92% Poor respiratory effort - exhaustion Silent chest Hypotension Cyanosis Altered consciousness Normal PaCO2 PaO2 <8kPa Arrythmia
Treatment of acute asthma
Oxygen 15L
- Nebulised salbutamol 5mg (repeat every 10-15m)
- Nebulised ipratropium 500mcg
- Specialist help - consider IV Magnesium sulphate 2g over 20m or Aminophylline
ALSO patients will need oral or IV steroids:
- Oral prednisolone 30mg (moderate/severe)
- IV hydrocortisone 100mg (severe/life-threatening)
- These are continued for 5 days
Antibiotics if evidence of bacterial infection
What indicates near-fatal asthma?
CO2 retention - call ICU
Examples of SABA, ICS
SABA - salbutamol, terbutaline
ICS - beclometasone, budesonide, fluticasone
What is the ABG likely to show in acute asthma?
Initially Respiratory alkalosis due to tachypnoea causing a drop in CO2
Respiratory acidosis due to high CO2 is a very bad sign in acute asthma
Further management after exacerbation
Discharge patients with an asthma action plan
Make sure they get an asthma review - may need to step up medication
Consider rescue pack of steroids for further exacerbations for the patient to initiate
Investigations in acute asthma
Peak flow
ABG - (BTS recommends if sats <92%)
CXR not routinely done unless - suspected pneumothorax, life-threatening asthma, failure to respond to treatmetn
Criteria for discharge following asthma exacerbation
been stable on their discharge medication (i.e. no nebulisers or oxygen) for 12–24 hours
inhaler technique checked and recorded
PEF >75% of best or predicted
