Asthma Flashcards
What is asthma?
- Chronic inflammatory condition of airways causing episodic exacerbations of bronchoconstriction
What are the 3 factors that causes airway narrowing?
- Bronchial muscle contraction
- triggered by stimuli
- Mucosal swelling
- mast cell & basophil degranulation
- Increased mucus production
What are the typical triggers of asthma?
- Smoking, pollution
- Infection - mainly viral
- Night time or early morning
- Exercise
- Animals
- Cold/damp
- Dust
- Stress
- NSAIDs
- B-blockers
- Pollution
- Occupational asthma (flour, latex, isocyanates, wood dust)
What are the RF for asthma?
- Personal history of atopy.
- Family history of asthma or atopy.
- Inner city environment; socio-economic deprivation.
- Obesity.
- Viral infections in early childhood.
- Smoking.
- Maternal smoking.
- Early exposure to broad-spectrum antibiotics
What are the sx of Asthma?
- Wheeze
- SOB
- chest tightness
- Cough
What features of the sx increase the probability of asthma?
- Diurnal variation
- response to exercise, allergen, cold air
- present after taking aspirin or b-blocker
- History of atopic disorder.
- Family history of asthma and/or atopic disorder.
- Widespread wheeze heard on auscultation of the chest.
- unexplained low forced expiratory volume in one second (FEV1)
- unexplained peripheral blood eosinophilia.
What signs will you find on examination for asthma?
- Inspection
- Tachypnoea
- Hyperinflated chest
- Expiratory wheeze
- Prolonged expiration
- Harrison’s sulcus seen in children with chronic asthma
- palpation
- Hyper-resonant percussion note
- Auscultation
- Reduced air entry
- widespread polyphonic wheeze
What are the 3 characteristics of Asthma?
- Reversible airflow limitation
- Airway hyperresponsiveness
- Inflammation of bronchi
How would you diagnose Asthma?
*this is for intermediate asthma probability
- First line
- Fractional exhaled nitric oxide (FeNO>40ppb)
- Spirometry c bronchodilator reversibility
- If diagnostic uncertainty
- Peak flow variability - measured several times/day
- Methacholine challenge test
- Additional
- TLCO - raised
What are the differentials for asthma in adults?
- COPD
- Asthma-COPD overlap syndrome
- persistent airflow limitation with several features of asthma and COPD
- Acute asthma
- Acute Bronchitis
- Heart Failure
- CHD
- Malignancy
- GORD
What affects peak expiratory flow rate?
- Sex
- Age
- Height
Why is spirometry preferred over PEFR?
- offer clearer identification of airway obstruction
- less effort-dependent
- more repeatable
How does FeNO work?
- Measures level of nitric oxide in the breath
- Increased levels - lung inflammation and asthma
What are the list of medications used for asthma?
- SABA - salbutamol
- ICS - beclometasone
- LABA - salmeterol
- LAMA - tiotropium
- LRA - montelukast
- Phosphodiesterase inh. - Theophylline
- Maintenance And Reliever Therapy (MART)
- low dose ICS + fast acting LABA
What is the BTS/SIGN Stepwise ladder for mx of chronic asthma?
- SABA PRN. If use >3 times/week > step up
- Add low dose ICS (200-800mcg/day)
- Add LABA (Fostair - contains both ICS and LABA)
- Medium dose ICS/Montelukast
- Specialist referral
What are the cx of asthma?
- Pneumonia.
- Pneumothorax.
- Pneumomediastinum.
- Respiratory failure and arrest
What is brittle asthma?
- Unstable/unpredictable asthma
What are the features of moderate asthma?
- PEFR 50-75% best or predicted
- Speech normal
- RR < 25 / min
- Pulse < 110 bpm
What are the features of severe asthma?
- PEFR 33 - 50% best or predicted
- Can’t complete sentences
- RR > 25/min
- Pulse > 110 bpm
What are the features of Life-threatening asthma?
- PEFR < 33% best or predicted
- Oxygen sats < 92%
- Silent chest, cyanosis or feeble respiratory effort
- Bradycardia, dysrhythmia or hypotension
- Exhaustion, confusion or coma
What are the features of near fatal asthma?
- Respiratory arrest
- Raised PaCO2
- Altered conscoiusness
- Required mechanical ventilation
What does TLCO measure?
- gas transfer for the lungs from the alveoli into the capillaries
- reflects how much oxygen is taken up into the red cells
Aspirin can induce asthma and cause Samter’s triad. What is this triad?
- asthma
- aspirin sensitivity
- nasal polyps
What are the features of mild asthma?
- PEFR >75%
What are the causes of eosinophilia?
- Asthma/COPD
- Hayfever / allergies
- Allergic Bronchopulmonary Aspergillosis
- Churg-Strauss
- Drugs (allopurinol)
- Eosinophilic Myalgia Syndrome
- Lymphoma
- Parasite - Ascariasis
- SLE
What is the pathophysiology of Asthma
- Airway epithelial damage - shedding and subepithelial fibrosis, basement membrane thickening
- Inflammatory reaction - eosinophils, Th2, mast cells
- Inflammatory mediators release - histamine, leukotrines, prostaglandins
- Cytokines amplify inflammatory response
- Increase mucus secreting goblet cells, smooth muscle hyperplasia, hypertrophy
- Mucus plugging in fatal and severe asthma
What are the criteria for safe asthma discharge after exacerbation?
- PEFR >75%
- Stop regular neb for 24hrs prior to discharge
- Reassess inhaler technique and adherence - by inpatient asthma nurse
- Provide PEFR meter and written asthma action plan
- 5 days oral prednisolone
- GP follow up within 2 days
- Resp clinic follow up within 4 weeks
Asthma can be classified into moderate, severe, life threatening and near fatal. Describe the features of each category
*think sx, vitals, sat, PEFR
What parameters would you wan to maintain control in chronic asthma?
- Clinical: make sure no daytime symptoms, night-time waking or activity limitation
- Acute: make sure no asthma attacks and no need for rescue medication
- Medications: make sure no need for rescue medication, ensure minimal side-effects from medication
- Lung function: normal (PEF/FEV1)
How would you diagnose occupational induce asthma?
- Serial peak flow measurements at work and at home
What factors should be considered when considering asthma?
- recurrent episodes of symptoms: may be triggered by viral infection, allergen exposure, NSAIDs/beta-blockers and/or exacerbated by exercise, cold air and emotion/laughter in children
- recorded observation of wheeze: due to varying use of language this usually means wheeze documented by a clinician
- symptom variability: asthma is generally worse at night or early in the morning
- personal history of atopy: e.g. eczema/allergic rhinitis
- absence of symptoms of alternative diagnosis: e.g. COPD, dysfunctional breathing or obesity*
- historical record of variable peak flows or FEV1
