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