Asthma Flashcards
Describe Asthma
Chronic inflammatory disease characterised by reversible bronchoconstriction and airway hypersensitivity
What are the classical features of Asthma?
Recurrent (reversible) episodes of -wheeze (widespread, expiratory) -cough (nocturnal) -dyspnoea -chest tightness Sx worse at night (peak flow worst in morning)
What three factors contribute to airway narrowing?
Bronchial muscle contraction
Mucosal swelling/inflammation
Increased mucus production
What are the common symptoms of Asthma?
Intermittent dyspnoea, wheeze, cough
Cough often nocturnal
Sputum production
Describe childhood (extrinsic) Asthma
Presents early w/ classical symptoms
Type 1 Hypersensitivity reaction
Precipitants often atopic
Can disappear in later life
Describe adult (intrinsic) Asthma
Presents late in life w/ classical symptoms Non-immune More severe, quicker deterioration Precipitants less atopic -cold -laughing -stress
Describe the early phase of an Asthma attack
Histamine/Leukotriene/Prost D2 release from mast cell causes contraction of bronchial smooth muscle
Describe the laterphase of an Asthma attack
Mucus production from inflammatory cells - repeated attacks damages lining
Airway hyper-reactivity can lead to acute deteriorations
Define chronic Asthma
Persistent airway obstruction b/w attacks
Bronchoconstriction & mucosal oedema
A diurnal variation of >20% on >3/7 for 2/52
What are the common precipitants of an Asthma attack?
Cold air Exercise Emotion Allergens - Pet dander, dust, pollen Viral infection Smoking Pollution Drugs - NSAIDs, B-blockers
What are the clinical features of an acute, severe asthmatic attack?
Tachycardia (>110) Tachypnoea (>25) Pulsus paradoxus Bilateral widespread expiratory wheeze Inability to complete sentences PEF <33-50% predicted
What is Pulsus Paradoxus?
An abnormally large drop in systolic BP and pulse wave amplitude during inspiration
What is the immediate investigation required in acute, severe asthma?
ABG
CXR only if suspected pneuom/consol OR if patient requires IPPV
What features can suggest a life threatening asthma attack?
Silent chest, cyanosis, poor resp effort Exhaustion/confusion Bradycardia, hypotension, dysrhythmia PEF <33% predicted SpO2 <90%
What ABG abnormalities would be indicative of severe/life threatening asthma?
Low pH PaO2 <8.0kPa PaCO2 4.6-6.0kPa -PaCO2 can be high in life threatening asthma/chronic attacks HYPERVENTILATION CAN CONFUSE ISSUES
What is good inhaler technique for MDIs?
Breathe out first Shake MDI between puffs Inhale immediately after pressing canister Hold breath 10 secs Leave 30-seconds between puffs
What is good inhaler technique for DPIs?
Breathe out first
Inhale hard
Hold breath 10 secs
What morphological airway changes occur in Asthma?
Fragile epithelial cells (upregulation of EDGF) Reticular basement membrane thickening Proliferation of airway SM Golbet cell/submucosal gland hyperplasia Oedematous swelling of airway wall
What are the key points when taking a history of asthma?
Known precipitants Diurnal variation in sx Associated reflux Atopy hx Occupation - days off History of exacerbations - ITU?
What is the structure of asthma diagnosis?
Clinical diagnosis Patients classified as high/low probability of asthma If high then treat as asthma -if improves then confirm diagnosis -if poor response refer for spirometry
What spirometry values are diagnostic of asthma?
FEV1/FVC <70% w/ bronchodilator reversibility
What does the sputum of a chronic asthma pt contain?
Charcot-Leyden crystals
Curschman spirals
What is the major complication of chronic asthma?
Pulmonary HTN
What is the management of severe asthma?
O2 - 15L/min via non-rebreather Salbutamol 5mg via neb (Terb 10mg) Ipratropium 0.5mg via neb Oral pred 50mg OR IV hydrocortisone 100mg NO SEDATIVES
