Asthma and COPD
Roger Deering + Phil Thirkell
Asthma - Definition
A chronic inflammatory disorder of the airways… Symptoms usually associated with variable airflow obstruction and an increase in airway response to a variety of stimuli. Obstruction is often reversible.
COPD - Definition
• Irreversible aspect of– Emphysema– Chronic bronchitis– Asthma
• Pulmonary component = airflow limitation (not fully reversible and usually progressive)
Pathology – Asthma Triggers• Allergens• Air pollution• Infection• Exercise• Smoking• Pets
Pathology – COPD
Large Airway•Mucus hypersecretion.•Neutrophils in sputum.•Squamous metaplasia of epithelium – no basement membrane thickening. •↑ macrophages.•↑ CD8 lymphocytes•Mucus gland hyperplasia•Goblet cell hyperplasia•Little increase in airway smooth muscle
Small Airway•Inflammatory exudate in lumen.•Disrupted alveolar attachments. •Thickened wall with inflammatory cells (macrophages, CD8s and fibroblasts).•Peribronchial fibrosis.•Lymphoid follicle – in severe COPD
Lung Parenchyma
•Alveolar wall destruction.•Loss of elasticity.•Destruction of pulmonary capillary bed.•↑ inflammatory cells, macrophages, CD8 lymphocytes
Result = Airflow limitation
Causes of airflow limitation – in simpler terms
•Fibrosis = narrowing of lumen.•Alveolar destruction = loss of elastic recoil.•Destruction of surrounding alveolar support = loss of small airway patency.
Irreversible
•Accumulation of inflammatory cells, mucus and exudate.•Smooth muscle contraction.•Dynamic hyperinflation.
Reversible
Pathology – COPD
Risk Factors
Host Factors
Genetic (a1-
antritrypsin
deficiency)
Hyper-responsiv
eness
Cells involved
Let’s get clinical!
AsthmaSigns/symptoms• Wheeze• Cough• Chest tightness• Dyspnoea• DIB
Things to look for on Hx• Date of onset• Other atopic disease• Family Hx• Smoking/Occupation/Pets• Provocation
3 things to ask• Day time control• Amount of relieving meds required• Night time control
Peak Flow – mainly asthma monitoring at GP and home
– Stand up– Breathe out– Maximum breath in– Seal lips around cardboard tube– Blow out as hard and fast as possible
• litres/minute• Best of 3 readings• Depends on technique – practice required• Peak flow diary
Spirometry – diagnosis/differentiation of asthma/COPD and monitoring
• Forced vital capacity - FVC• Forced expiratory volume in 1 second – FEV1
• GP surgery - nurses trained for spirometry• Predicted FEV1 and FVC - Height, Weight, Age, Gender
• <80% of predicted for FVC or FEV1 is abnormal• FEV1/FVC ratio differentiates asthma and COPD
– <0.7 = obstructive lung disease– >0.7 = restrictive lung disease
Contraindications: recent surgery, ENT disorders, recent pneumothorax, haemoptysis, communicable disease
Reversibility/Bronchoprovocation
Reversibility– Give salbutamol and retest FEV1. If increased after
salbutamol it’s more likely to be asthma, not COPD
• Bronchoprovocation– Checking for hypersensitivity in asthma– Nebulised histamine or methacholine causes
airway constriction, seen in asthma
Obstructive vs. Restrictive
• Obstructive– Narrowed airways, reduces the amount of air that
can pass through at any time– Reduces FEV1
• e.g. COPD and Asthma
• Restrictive– Lungs can’t expand as much, so FVC is reduced• e.g. Interstitial lung diseases, sarcoidosis, obesity
obstructive
restrictive
Management of Asthma and COPD
• Patient education– symptom recognition– allergen avoidance– exercise– diet– smoking cessation
Asthma
COPD
• Stop smoking• β2-agonists• Anti-cholinergics• Steroids• Methylxanthines (theophylline)• Long term oxygen therapy (LTOT)
• Infection prevention – flu jab• Rescue packs – steroids + antibiotics
β2-agonists – salbutamol, salmeterol
• Reliever inhalers• Relax smooth muscles in airways• Activates G-protein coupled receptors• Tolerance develops
SE: tremor, headache, tachycardia
Anti-Cholinergics – ipratropium, tiotropium (inhalers)
• Blocks muscarinic receptors (M3) of the parasympathetic NS
• Reduces contraction to open airways
SE: dry mouth, constipation, urinary retention
• Methylxanthines (theophyllines/aminophylline)– ↑ PDE– Need close monitoring– SE: insomnia, nausea, vomiting
• Leukotriene Antagonists (montelukast)– Block inflammatory phase– Tablet, used as a preventer
• Steroids (beclometasone, prednisolone)– Preventers– Reduce inflammation– Loads of side effects
• Inhaled• Oral
• Mast Cell Stabilisers (sodium cromoglycate)– Reduces histamine release from mast cells
• Monoclonal antibodies (omalizumab)– Binds IgE to stop histamine release from mast cells– Expensive
Asthma Attack Management
O – high flow Oxygen
S – salbutamol (nebulised)H – hydrocortisone (IV)I – ipratropium (IV)T – theophylline (IV)
+ intubation