Acute and Chronic Asthma Flashcards
What is the pathophysiology of asthma?
Chronic inflammatory disease of the airways
Airway obstruction that is reversible (but not completely so in some subjects), either spontaneously or with treatment = bronchial muscle contraction, mucosal inflam, increased mucus production
Increased airway responsiveness (airway narrowing) to a variety of stimuli
Outline the aetiology of asthma
Not fully understood
Strongest risk factors are a combination of genetic predisposition with environmental exposure to inhaled substances that may provoke allergic reactions
What are the symptoms and signs of asthma?
- Intermittent dyspnoea
- Wheeze - polyphonic
- Cough - often worse at night (poor performance at school/activities)
- Inability to complete sentences
- RR increased
- Pulse increased
- Disturbed sleep
- Precipitants = cold air, exercise, emotion, allergens
Poor control = need for bronchodilators >3/w, >5d absence per term, >1 ep of cough/wheeze per month
How should asthma be investigated?
Peak flow 33-50% (diaries)
Lung function testing = scooped curve, FEV1:FVC <70, DLCO normal, reversible >12% increase FEV1
Fractional exhaled nitric oxide (FeNO) = measures the level of NO in the exhaled breath and provides an indication of eosinophilic inflammation
Acute = ABG, CXR
How should acute asthma be managed?
Peak flow = assess severity
A-E assessment = capillary blood gas, CXR
- oxygen, non-rebreathe 15L (if sats <94%)
- salbutamol inhaler with spacer, 10x
- PO/IV prednisolone
- salbutamol nebuliser (risk of hypoK)
- ipratropium bromide mixed with salbutamol nebuliser
- IV salbutamol
- IV aminophylline
- IV 2g magnesium sulphate
How should chronic asthma be managed?
S = Smoking cessation, skin prick = identify allergen I = Inhaler technique M = monitoring P = pharmacotherapy (below) L = lifestyle E = education
- Short acting beta 2 agonist (Salbutamol) = Sx relief
- Add very low dose ICS (Beclomethasone)
- Add
- >5y LABA (Salmeterol)
- <5y LTRA (Montelukast) - Beclomethasone medium dose, theophylline
- Oral prednisolone
Name some possible complications of asthma
Pneumonia
Lung collapse
Respiratory failure
What are the features of moderate asthma?
Sats >92%, pulse <110, RR <25
Wheeze ++
PEFR 50-75%
What are the features of severe acute asthma?
Peak flow 33-50%
Inability to complete sentences, accessory muscle use, inability to feed, O2 sats <92%
RR
- > 25/min >12y
- > 30/min 5-12y
- > 40/min 2-5y
Pulse
- > 110/min >12y
- > 125/min 5-12y
- > 140/min 2-5y
What are the features of life threatening asthma?
Peak flow <33% Sats <92% Silent chest Bradycardia Diminished resp effort Hypotension Exhaustion Coma, confusion, altered consciousness Signs of hypercapnia Cyanosis
What are the histological features of asthma?
Bronchial obstruction Thickening of the basement membrane Mucosal thickening Mucus plugging Bronchial smooth muscle hypertrophy
What are common triggers of acute asthma?
Cold air Exercise Allergens = pollution, dust mites, pollen, fur Infection Smoking/passive NSAIDs Beta-blockers
What are the causes of a paediatric wheeze?
Viral-induced wheeze - rhinovirus
Foreign body aspiration (CXR exhalation - over inflated blocked lung, other deflated)
LRTI - bronchiolitis, viral pneumonitis
Asthma
Bacterial bronchitis
Bronchomalacia - weak cartilage in the walls of the bronchial tubes
Prematurity
How does poorly controlled asthma present and what are the causes?
Present = salbutamol most days, cough at night, tight chest with exercise
Aetiology = non-adherence, poor inhaler technique, inadequate maintenance therapy, environment (passive smoke, started smoking, damp, mould), allergic rhinitis, chest infection
Gives types of examples of preventers used to manage asthma
Inhaled steroids = beclomethasone, budesonide, fluticasone
LABA = salmeterol, formoterol
Leukotriene antagonist = Montelukast
Methyxanthines = theophylline
