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Chronic Obstructive Pulmonary Disease (COPD)

Considerations

The Global Initiative of Chronic Obstructive Lung Disease (GOLD) – a project initiated by the US National Heart, Lung, and Blood institute (NHLBI) and the World Health Organisation defines COPD as follows:

'Chronic obstructive pulmonary disease (COPD), a common preventable and treatable disease, is characterized by airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lung to noxious particles or gases. Exacerbations and comorbidities contribute to the overall severity in individual patients.'

COPD may be caused by chronic bronchitis, chronic asthma, emphysema, and alpha-1 antitrypsin deficiency. The most important risk factor for COPD is smoking. Around 80% of people affected by COPD have a history of smoking. In the absence of genetic / environmental predispositions, smoking less than 10 pack years is unlikely to result in COPD while smoking more than 40 pack years has a positive likelihood ratio of 12 [Confidence interval 2.7-50]. Thus inquiring about smoking habits is important.

Symptoms of COPD include chronic chough, sputum production and dyspnoea. Exertional dyspnoea is an early symptom.

Pulmonary functions tests are the cornerstone in the diagnosis of COPD. The most important values measured during spirometry are the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC). The post bronchodilator ratio FEV1/FVC determines the severity of irreversible airflow limitation. A ratio of less than 0.7 is considered abnormal however the normal value decreases with age. The force expiratory volume in six seconds (FEV6) obtained by stopping expiratory effort a 6 seconds is an acceptable surrogate for FVC. Spirometry reference values are available from:

cdc.gov/niosh/topics/spirometry(external link)

Please refer also to the Asthma section for spirometry normal values.

Staging of COPD

The Revised GOLD Classification looks at three things: Symptoms (Dyspnoea), FEV1 and history of Exacerbations.

Dyspnoea

Grade 0: 'I only get breathless with strenuous exercise.'
Grade 1: 'I get short of breath when hurrying on level ground or walking up a slight hill.'
Grade 2: 'On level ground, I walk slower than people of the same age because of breathlessness, of have to stop for breath when walking at my own pace.'
Grade 3: 'I stop for breath after walking about 100 meters or after a few minutes on level ground.'
Grade 4: 'I am too breathless to leave the house or I am breathless when dressing.'

FEV1

GOLD 1 Mild FEV1>80% of predicted (but has other positive markers)
GOLD 2 Moderate 50% <FEV1<80%
GOLD 3 Severe 30% <FEV1<50%
GOLD 4 Very severe FEV1 <30%

Exacerbations

Low risk: 1 or less exacerbations per year
High risk: 2 or more exacerbations per year

Information to be provided

  • Routine spirometry at the first application in accordance with the GD 'timing of routine examination';
  • Routine spirometry at age 46 and 56 if the applicant has ever smoked tobacco, in accordance with the GD 'timing of routine examination';
  • Spirometry at any application when an applicant presents with a history, signs or symptoms suggestive of lung disease;
  • The spirometry is to include post bronchodilator recordings if the FEV1 is less than 80% of predicted or if the FEV1/FVC is less than 70%;
  • Pulse Oximetry Oxygen Saturation result if COPD is suspected;
  • Consider altitude simulation (FiO2 15%) oximetry at rest and with exercise if there is concern regarding abnormal gas exchange;
  • GP notes for the past 24 months if the applicant reports attending for respiratory problems or the ME is uncertain about the history given;
  • A respiratory physician report, on the first occasion that the FEV1/FVC is less < 60%, or SaO2 < 95%, or if the applicant has attended for respiratory problems or has signs or symptoms suggestive of more than mild COPD.

Disposition

  • A Class 1 applicant with mild COPD may be considered as having a condition that is not of aeromedical significance if: the FEV1 is 70 % of predicted or better, the Dyspnoea Grade 1 or less, the pulse oxymetry 95% or better, and there is no history of exacerbation;
  • A Class 2, or 3 applicant with mild to moderate COPD may be considered as having a condition that is not of aeromedical significance if: the FEV1 is 60% of predicted or better, the Dyspnoea is Grade 1 or less, the pulse oxymetry 95% or better, and there is no more than one exacerbations per year.
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