COPD

Chronic Obstructive Pulmonary Disease is a chronic, progressive, irreversible airway obstruction caused by lung tissue damage, which is almost always due to smoking. This obstruction makes ventilation more difficult, therefore making patients more prone to infections. The main feature that differentiates it from asthma is its irreversibility w/bronchodilators.

It's main risk factors are Smoking, Age, and Occupational exposure.

Presentation

• Productive cough

• Dyspnoea

• Reduced exercise tolerance

• Wheeze

Complications:

• Infective exacerbations

• Polycythaemia

• Cor pulmonale

• Respiratory failure

• Pneumothorax

• Lung cancer

Chronic Bronchitis

With this, the chronic exposure to noxious particles, such as smoking or air pollutants, causes increased mucus production and airway inflammation. The fibrotic changes from this results in narrowing and chronic obstruction. Smoking also destroys cilia, therefore leading to increased susceptibility to infections.

These patients are known as BLUE BLOATERS as they're overweight and cyanosed.

Clinical features:

• Chronic productive cough

• Cyanosis

• Hypoxic and Hypercapnic (decreased alveolar ventilation)

• Peripheral oedema

The main complications here are Cor Pulmonale (signs of RHF) and Polycythaemia (as a response to chronic hypoxia).

In these patients, their respiratory centres become insensitive to CO2, so they develop a hypoxic drive. Oxygen has to be given with caution as too much of it will decrease their respiratory drive.

Emphysema

With this, there's permanent enlargement and damage of airspaces, therefore reducing alveolar surface area and efficient gaseous exchange.

• Smoking stimulates the production of neutrophil elastase, which destroys alveolar walls

• α1-antitrypsin inhibits neutrophil elastase, so its deficiency leads to more damage

Overall, there’s loss of elastic recoil and subsequent airway collapse during expiration, with air trapping.

These patients are known as PINK PUFFERS as they're older and thin, but not cyanosed.

Clinical features:

• Exertional dyspnoea

• Pursed lip breathing

• Barrel chest (hyper-expansion)

• Sitting forward in a hunched-over position

The main complication here is Type 1 respiratory failure.

Investigations

COPD should be suspected in a chronic smoker that presents with chronic exertional dyspnoea, productive cough, wheeze, and recurrent chest infections.

The main invesitgation to do here is a Spirometry, which will show an obstructive pattern with FEV1/FVC < 0.7. To rule out asthma, a bronchodilator can be given to check for any reversibility.

Other investigations to do include:

• Bloods - FBC (polycythaemia)

• ABG (respiratory failure and raised HCO3-)

• ECG and Echo - Signs of Right heart strain/failure (cor pulmonale)

• CXR - Hyperinflation (6+ anterior ribs), Flattened diaphragm, Bullae

• Serum α1 antitrypsin to look for deficiency, which leads to early onset of symptoms and more severe disease

Management

Non-pharmacological - Smoking cessation, Annual flu vaccine, Nutritional support, Pulmonary rehab

Stepwise approach:

• SABA/SAMA (e.g. salbutamol/ipratropium)

• Check for features of asthma/steroid responsiveness

  • If NO - Add on LABA + LAMA

  • If YES - Add on LABA + ICS

• LABA + LAMA + ICS if still no improvement

Other medications to consider giving include:

• Mucolytics e.g. carbocisteine

• Long-term prophylactic Abx e.g. azithromycin

N.B. Asthmatic features include atopy, raised eosinophils, reduced FEV1, or PEF variations > 20%.

Long-Term Oxygen Therapy (LTOT)

This is considered if:

• pO2 < 7.3kPa on 2 readings over 3 weeks apart + non-smoker OR

• pO2 7.3 - 8kPa alongside one of: nocturnal hypoxia, polycythaemia, peripheral oedema or pulmonary hypertension

N.B. Not to be used in active smokers (oxygen + cigarettes is a fire hazard).