Asthma Flashcards
What is asthma
Airways smooth muscle hyper responsiveness leading to periodic, at least partly reversible obstruction of the airways
What is the obstruction caused by
Inflammation/swelling of the mucosal lining.
What does the obstruction cause
Turbulent airflow - audible wheeze. Should hear in all lung fields
What are signs of pneumothorax
Hyper resonant and no breath sounds
What are signs of pneumonia
Bacterial infection of one lobe - dull percussion
What are signs of lung collapse
Blockage in proximal airway, dull percussion everywhere
How is asthma severity assessed
PEFR/FEV1 and response to bronchodilator (nebulised salbutamol 5mg given with pure O2)
Blood gases: oximetry <92%
Who are high risk asthma px
Poor compliance, psychosis, depression, denial, alcohol or drug abuse, obesity, social problems, severe stress from any source
What is cyanosis a sign of
Terminal sign of asthma (pO2 has to be around 50)
What does hypercapnia cause in the brain
Hypercapnia is a potent vasodilator - causes cerebral oedema
When should an asthma px be admitted
FEV1/PERF less than 50%, predicted 15-30 minutes after bronchodilator
What is the management for admitted severe asthma
Oxygen - high conc up to 100%
Hypercapnia is asthma reflects alveolar hypoventilation and not lung disease
Inhaled beta2-agonits (prevents bronchospasm)
Nebulised
Give continuously if necessary
Always nebulise with O2: may acute aggravate hypoxia in severe asthma; hypoxia and hypercapnia alter cardiac response to beta2-agonist
If px does not have access to nebuliser, breath in Ventolin through spacer
Ipatropium bromide 0.5 mg 4-6hourly added to beta2-agonist if acute severe or life threatening asthma
What is given IV in severe asthma
Single bolus of IV magnesium sulphate if PEF<50%
What is the role of steroids in acute asthma
Glucocorticoids: given orally
Reduction in airflow obstruction begins 1-3 hours, peaks 5-9 hours after single dose
Probably no need to give 0.6 mg/kg prednisolone in 24 hours; typical emergency regimens are 2-3 mg/kg hydrocortisone 4 hourly
What to do with acute asthma px with a good response to management
Continue oxygen, nebulised beta2-agonsits 4 hourly, glucocorticoids
Do not discontinue any existing inhaled glucocorticoid therapy
What to do with acute asthma px with a poor response to management
Continuous high flow oxygen Nebulised beta2-agonist every 15-30 mins Consider complications Hypokalaemia (beta agonists cause migration of potassium ions intracellularly) Coexisting problems Admit to intensive care
How is vent support given with asthma
Benzodiazepine and pancuronium sedation
Aim to correct hypoxaemia with permissive hypercapnia
What is allergic asthma
most easily recognised, usually commences in childhood. Associated with Fx. Usually presents eosinophilic airway inflammation. Good responses to ICS
What is non allergic asthma
sputum may be neutrophilic, eosinophilic or with few inflammatory cells. Less response to ICS
What is late onset asthma
more common in women. Tendency to non-allergic, higher doses of ICS
What is asthma with fixed airflow limitation
long standing asthma, airflow limitation thought to be due to airway wall remodelling
What is asthma with obesity
prominent resp symptoms, little eosinophilia
What are the inflammatory pathologies of asthma
Inflammatory infiltrate (Th2, mast cells and eosinophils)
Mucosal oedema:
Bronchial microvascular leak
Mucus hypersecretion: Blockage of airways
Bronchial smooth muscle contraction:
Action of inflammatory mediators
What are the remodelling pathologies of asthma
Reticular BM thickening
Airway smooth muscle thickening
Submucosal mucus gland hypertrophy
