Chronic Obstructive Pulmonary Disease (COPD)

Introduction

- Chronic, slowly progressive disorder of fixed (or minimally reversible) airways obstruction.

- Airway obstruction secondary to loss of alveolar attachments, inflammatory obstruction and mucus plugs.

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Sub-categories of COPD

Chronic bronchitis
- Clinical differential diagnosis
- A cough with mucoid expectoration for ³ 3 months in a year for 2 successive years that is not due to a specific disease (e.g. bronchiectasis / TB)

Emphysema
- Pathological differential diagnosis
- abnormal permanent enlargement of the airway distal to the terminal respiratory bronchioles with destruction of their walls
- 2 types:

1. Centrilobular (smoking, pneumoconiosis)
2. Panacinar (alpha-1 antitrypsin defiecincy)

Other
- bronchiectasis
- chronic asthma
- cystic fibrosis

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Clinical features

- patient > 35 yrs old
- smoker / ex-smoker
- Progressive symptoms (dyspnoea, cough, wheeze)
- Not reversible (unlike asthma, which shows reversibility with beta-2 agonists)

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Management of COPD: conservative

Smoking cessation
- cessation clinics
- nicotine replacement
- Bupropion

Pulmonary rehabilitation
- exercise training
- if functionally disabled (=/>MRC grade 3)

Management of COPD: medical

Bronchodilators
- beta-2 agonists
- ACh antagonists

Steroids
- steroid responsiveness trial (symptoms improve in 10%)
- no effect on course of disease

Methyl xanthines
- theophylline (PO)

Vaccinations
- influenza
- pneumococcus

Home oxygen therapy if:
- non-smoker
- severe COPD (FEV1 <1.5L, FVC <2L / cor pulmonale)
- chronic respiratory failure (PaO2 <7.3kPa on room air)
- type I failure (PaCO2 normal on O2)

Note:
2–4L/min via nasal prongs >15 hours day –1 prolongs survival by 9 months: this is the ONLY COPD treatment that improves life-expectancy.

Management of COPD: surgical

- bullectomy (if bullae >1L)
- lung reduction surgery (improves elastic recoil)
- lung transplant

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Management of COPD: acute exacerbation

15% in-patient mortality

History
- dyspnoea
- sputum volume
- sputum purulence

Investigations
- sputum culture (H. influenzae, S. pneumoniae, M. catarrhalis)
- CXR pneumonia / pneumothorax
- ABGs (first-line investigation)
- ECG
- bloods (FBC, U+Es, CRP, theophylline levels)

Initial management
Controlled O2
- 24% Venturi mask
- aim for SaO2 >90%

Bronchodilators
- terbutaline (nebs)
- ipratropium bromide (nebs)

Antibiotics
-amoxicillin (IV)

Steroids
- prednisolone (PO)
- hydrocortisone (IV)

If poor response:
(IV) theophyllines
- aminphylline

Resp stimulants
- doxapram

Ventilation
- NIPPV: BIPAP via face-mask
- IPPV: intubation