Asthma Flashcards
Pathophysiology
Defined: condition in which there is a recurrent ‘reversible’ obstruction of airflow in the airway due to a stimuli that is not normally considered to be noxious and would not affect a non-asthmatic subject.
2 Main causes of air flow limitation:
*Bronchial hyper-responsiveness (easily-triggered bronchospasm)
*Inflammatory changes in the airways.
Asthma attack consists of a combination of an immediate bronchospasm, due to exposure to a stimulus, followed by a later phase of bronchiole inflammation, in which local blood vessels dilate, oedema forms and excess mucus is produced.
Inflammatory phase caused by eosinophils releasing inflammatory mediators.
Therefore = bronchial smooth muscle contracting and the linings of the airways becoming inflamed, the calibre of the airways becomes much reduced, so making breathing difficult.
Allergic asthma = initiation by sensitization to specific allergen. Will be slow 1st time but 2nd time faster. involves antigen presenting cells (APC) presenting an antigenic peptide fragment of the allergen, via MHC (major histocompatibility complex) Class II to CD4+ T helper cells. chain of events occurs; development of Th0 lymphocytes, a rise in a clone of Th2 lymphocytes and their associated cytokines leads to expansion of B cells and plasma cells which produce IgE specific to that allergen and IgE receptors on mast cells. now sensitized. 2ND exposure to the same allergen will result in the allergen cross linking IgE and rapid mast cell degranulation.
Mast cell degranulation results in the release of spasmogens (mediators of bronchoconstriction) including histamine, PGD2 and cysteinyl leukotrienes (cysLTs) such as leukotrienes C4 and D4 (LTC4, LTD4) powerful mediators of bronchoconstriction (early phase). Chemotactic mediators also released promoting an influx of inflammatory cells (particularly T-h2 cells, eosinophils and monocytes) which 4-6 hours later results in a delayed inflammatory response (late phase)
Trigger factors
Occupation = eg car fumes, flour dust, animal dander, grain and poultry dust for agricultural workers
Pollen = Immune system overreact and release histamine. also can lead to blocked nose = breathe in through your mouth, the air you’re inhaling is colder and drier
Infection = URTI/LRTI. Can cause increased obstruction = more difficult breathing.
Smoke = Tobacco can settle in the lining of airways. also damage cilia which removes mucus.
Cold air/dry air = cold air can cause bronchi to constrict.
Exercise = use inhaler b4 it.
Signs & Symptoms
common = cough, wheeze, chest tightness, and breathlessness.
Vary over time and intensity can change.
Diagnosis
Take clinical history.
SUSPECT IF:
If symptoms are present - can be worse at night and early morning.
History of atopic disorder.
Widespread wheeze.
No single diagnostic test but some that can help are:
fractional exhaled nitric oxide (FeNO) testing, spirometry, bronchodilator reversibility (BDR), peak expiratory flow (PEF) readings, and direct bronchial challenge testing with histamine or methacholine.
FeNO results.
17+ = 40 ppb + = positive
5 -16 = 35 ppb + = positive
FeNO can be affected by ICS
FEV1/FVC <70% = air flow limitation.
Bronchodilator reversibility (BDR) = give to 17+ consider in 5 to 16 with FEV1/FVC <70%.
improvement of FEV1 12% or + with increase in volume of 200mL in response to beta agonist or corticosteroid = positive result. In children FEV1 improvement of 12% or + is positive.
Variable peak expiratory flow (PEF) readings can support an asthma diagnosis if there is diagnostic uncertainty after other above tests. >20% variability after monitoring at least BD for 2-4 weeks = positive
(more condition in cks)
NEED TO EXCLUDE OTHER CONDITONS DONE VIA:
Chest X ray, FBC = need to exclude - COPD, bronchiectasis, HF, PE or TB
Treatment (NON pharmacological)
Breast feeding
Weight reduction - Losing weight allows more room in the lungs as the visceral area does not contain as much fat.
Smoking cessation - Smoking irritates the airways, parents shouldn’t smoke too.
Immunisations - Influenza vaccine, pneumococcal vaccine small benefit
Breathing exercise - adjunct to pharmacotherapy to reduce symptoms and improve quality of life.
Treatment (Pharmacological)
Drug plan depends on severity.
SABA as reliever.
ICS as preventer for all who:
- use SABA 3 times a week or +
- symptoms 3 times a week or +
- Woken at night by symptoms once weekly or +
ICS dose depends on severity. Higher doses in smoker/ previous smokers. ICS normally BD. Over time adjust try get to lowest possible.
CHECK SIGN 158 DIAGRAMs HOW TO CONTROL IF THE ABOVE DONT WORK. FOR ADULTs and CHILDREN
EXAMPLES Inhalers:
LABA- Salmeterol, Formoterol, Indacaterol, Olodaterol
ICS + LABA - Formoterol + Beclomethasone (Fostair®)
Salmeterol + Fluticasone (Seretide®)
, Formoterol + budesonide (Symbicort®),
Vilanterol + fluticasone furoate
(Relvar®)
MAYBE FOR COPD ONLY CHECK PHONE FOR PHOTO EXAMPLES
EXACERBATION Treatment (Pharmacological)
Severity is graded as:
Moderate –
PEFR >50–75% best or predicted (at least 50% children) and normal speech, no features of acute severe or life-threatening asthma.
Acute severe –
PEFR 33–50% best or predicted, (<50% children) OR
RR of at least 25/min >12 years,
30/min 5-12 yrs, and
40/min 2-5 yrs, OR
Pulse rate at least 110/min >12 yrs, 125/min 5-12 yrs, and
140/min 2-5 yrs, OR any of
- inability to complete sentences in one breath,
- accessory muscle use,
- inability to feed (infants),
- + O2 sats of at least 92%.
Life-threatening –
PEFR <33% best or predicted, OR
O2 sats of <92%, OR any of
- altered consciousness,
- exhaustion,
- cardiac arrhythmia,
- hypotension,
- cyanosis,
- poor respiratory effort,
- silent chest,
- confusion.
IF NEED HOSPITAL-
SABA =
Life threatening/Severe =
nebulised salbutamol 5mg to all. 2.5 mg to 2-5 yrs
- O2 driven nebuliser avoid hypoxia if not available use air.
Intermittent nebuliser give salbutamol every 20-30 min. Continuous nebulizer, give over 30–60 minutes.
POOR response ALT nebulized ipratropium bromide (500mcg for adults, 250mcg for children 2–12 yrs, don’t repeat within 4 hours)
Moderate or no nebuliser = PMDI with large spacer. Adult 4 puffs then 2 puffs every 2 mins up to 10 Puffs. Repeat every 10-20 mins.
CHILD- puff every 30–60 secs, to 10 puffs.
Both severities - 1st dose of prednisolone (40–50 mg Adults, 30–40mg >5 yrs, 20mg 2–5 yrs, and 10mg <2 yrs).
CANT swallow = ALT IM methylprednisolone 160mg adults, or IV hydrocortisone 100mg >5 yrs, and 50mg 2–5 yrs.
Monitor PEFR (if the person can comply) and O2 sats (if available) to assess response to treatment.
DONT NEED HOSPITAL:
SABA + large spacer.
Adult, give 4 puffs initially, followed by 2 puffs every 2 minutes according to response, up to 10 puffs.
CHILD give a puff every 30–60 secs, up to 10 puffs. Each puff one at a time and inhaled with five tidal breaths. Repeat every 10–20 mins.
Adults - short prednisolone course.
NO ANTIBIOTICS UNLESS INFECTIONS SIGNS.
Consider initiating Montelukast in children >2 yrs with a mild asthma exacerbation early after the onset of symptoms.
Follow up
Normal follow up:
Annually, to see if treatment needs to be changed. monitor asthma control. At annual review advise on inhaler technique.
In all people monitor:
- Number of asthma attacks, oral corticosteroid use, time off school/nursery/work due to asthma
- nocturnal symptoms
- adherence
- possession/use of self management plan and asthma plan.
- exposure to tobacco smoke
In children monitor & record:
- Symptom score
- Growth
In adults monitor & record:
- Symptomatic asthma control
- Lung function
- Bronchodilators over use >12 SABAs / year
- Smoking status
- Possibility of occupational asthma
Asses risk of future attacks (info on on nice [scenario follow up])
People on long term steroid use monitor:
BP, Urine or Blood sugar, Cholesterol, Bone mineral density, Vision.
If medication is adjusted review response of treatment in 4 to 8 weeks.
ORAL MACROLIDE
50 - 70 years who have ongoing symptoms despite ICS who suffered 1 exacerbation in past year CAN HAVE PROPHYLACTIC ORAL MACROLIDE - reduce possibility of exacerbation frequency
- Azithromycin 500 mg 3/7 = minimum 6 -12 months.
B4 STARTING:
ECG, baseline LFTs, counselling on AEs.
LFTs should be checked 1 month after and then every 6 months. ECG 1 month after to check for new QT prolongation if present med should be stopped.
IF GI effects = reduce dose to 250 mg.
Follow up Exacerbation
Follow-up within 48 hours of presentation, if not admitted to hospital.
Follow-up all admitted to hospital within 2 working days of discharge.
Review symptoms and check PEF
Check inhaler technique.
Consider stepping-up treatment by increasing ICS or adding new preventer.
Advise on lifestyle, vaccinations diet, exercise, smoking.
Advise on recognising poor asthma control.
Consider giving oral corticosteroid for home use in case of exacerbation.
Consider referral to a respiratory physician if has had 2 asthma attacks within 12 months.
