Obstructive Conditions

Asthma

Asthma is a disease that is characterised by reversible bronchoconstriction, bronchial hyper-responsiveness, and airway inflammation.

Allergens induce a Th2 response which stimulates production of IgE and attracts eosinophils to the airways, leading to airway inflammation.

This leads to the release of chemical mediators (such as histamine and leukotrienes) which leads to bronchoconstriction increasing airway resistance.

Risk factors

Personal or family history of atopic conditions (allergic rhinitis, eczema)

Air pollution

Precipitants – cold air, allergens (ask about pets, carpet etc.)

Drugs – e.g., aspirin intolerant asthma (usually features nasal polyps)

Occupational (baking, factory work) – this classically causes reduced peak flow readings during the working week and normal readings when at home

Symptoms

Wheezing

Shortness of breath

Diurnal variation in symptoms (worse in morning and night)

Productive cough

Chest tightness

Expiratory wheeze

Reduced peak flow rate (especially in the mornings)

Key tests

For patients ≥ 17 years

Spirometry will indicate obstructive pattern – FEV1/FVC < 0.7

Bronchodilator reversibility testing (BDR) – this is positive if there is an improvement in FEV1 ≥ 12%, or an increase in volume ≥ 200 ml

Fractional exhaled nitric oxide test (FeNO) – positive if > 40 parts per billion (ppb)

For patients 5–16 years

BDR: a positive test is indicated by an improvement in FEV1 ≥ 12%

FeNO is usually only requested if normal spirometry or negative BDR test

FeNO: a level of > 35 parts per billion (ppb) is considered positive

Grading

Asthma exacerbation severity is divided into categories – moderate, severe, lifethreatening and near-fatal.

Acute management

If moderate:

SABA inhaler (ideally via a spacer)

Can be managed in community with a course of oral steroids

If acute-severe or more:

High flow oxygen therapy to maintain SpO2 94–98%

1st line is salbutamol nebulised with O2 (+ ipratropium) with IV/oral steroids

2nd line is IV magnesium sulphate with repeat nebulisers every 15 minutes

If unsuccessful, can add IV aminophylline (this should only be initiated by a senior and needs cardiac monitoring)

If still unresponsive patients may require intubation and ventilation

Chronic management

This involves using inhalers to prevent severity and frequency of exacerbations:

Patients are given a short-acting beta agonist (salbutamol) for relief of symptoms

Step 1: SABA + low dose inhaled corticosteroid (ICS)

Step 2: SABA + low dose ICS + leukotriene receptor antagonist (LTRA)

Step 3: SABA + low dose ICS + long-acting beta agonist

Step 4: Increase steroid dose and consider other drugs

Step 5: May require regular oral dose prednisolone (and refer to specialist)

COPD

This is a progressive disorder characterised by a triad of chronic bronchitis, emphysema, and small airways fibrosis. It is heavily associated with smoking.

Symptoms

Chronic cough with sputum, polyphonic expiratory wheeze, shortness of breath

Hyperexpanded chest (low cricosternal distance), hyper-resonance to percussion

Increased frequency of chest infections

Key tests

Spirometry shows obstructive pattern of disease. FEV1 helps assess COPD severity.

Chest X-ray – shows hyperinflated lungs, bullae and a flat hemidiaphragm

ABG is used to assess oxygenation status and assess for respiratory failure

Acute management

Oxygen therapy if needed (aim for 88–92% if CO2 retainer)

1st line is salbutamol and ipratropium nebulisers AND IV/oral steroids

Add antibiotics if evidence of bacterial infection (e.g., concomitant pneumonia)

If there is type 2 respiratory failure and no response to medical management for 1 hour, patients will require non-invasive ventilation (BiPAP

Chronic management

All patients have pulmonary rehabilitation, annual influenza vaccine and one-off pneumococcal vaccination. Some may also have azithromycin antibiotic prophylaxis.

1st line is SABA or SAMA inhalers

The next step considers whether the patient is steroid responsive or asthmatic:

If not steroid responsive, add LABA and LAMA inhaler (if on SAMA, switch to SABA)

If patient is steroid responsive, add ICS and LABA inhaler

If no response, patients should have combination LAMA-LABA-ICS therapy

Bronchiectasis

This refers to chronic inflammation of the bronchi and bronchioles, causing permanent dilation of the airways.

It is associated with airflow limitation and increased mucus production.

Causes

Post-infectious, e.g., TB, ABPA

Congenital, e.g., cystic fibrosis, primary ciliary dyskinesia

Lung disease, e.g., COPD, asthma

Symptoms

Persistent productive cough with copious purulent sputum, worse when lying down

Shortness of breath, wheezing, chest pain and coarse crackles on auscultation

Finger clubbing

Key tests

CXR shows tram tracking and parallel line shadows

Spirometry shows obstructive pattern of disease (FEV1/FVC < 0.7)

HRCT – this is the gold-standard diagnostic test which shows bronchial dilation with possible fibrosis of the lower lobes

Management

Pulmonary rehabilitation and antibiotics to treat recurrent infections.

Hypertonic saline nebulisers can be used to thin respiratory secretions