Investigations

Correct diagnosis is essential for treating COPD. The investigations include:

  • A detailed history often reveals the diagnosis

o    History of smoking; age at which smoking was started; total duration of smoking; total number of cigarettes smoked per day (maximum / day); type of cigarette smoked (with filter or without filter) and pipe or cigar.

o    History of any significant air pollution at home (like burning wood, coal or living in an ill-ventilated house).

o    History of air pollution at work place e.g. coal mining, etc.

o    Any family history of lung disease or emphysema. This history is important if an individual is a non smoker.

Tests for Diagnosis

  • Lung function test (Spirometry) is carried out with the aid of computerized machines.  It is an objective method to confirm the diagnosis and helps in assessing the severity of the disease. The 4 lung volumes most relevant to COPD  are Total Lung Capacity (TLC), Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV 1) and Residual Volume (RV). Most lung volumes show minor changes in COPD except Residual Volume which usually increases  markedly. The volume of air rapidly exhaled in one second after deep inhalation is known as FEV 1. As COPD progresses the amount of air that is exhaled (FEV 1) too diminishes. Infact more than expected annual fall in FEV1 is a fairly reasonable predictor of disability and early mortality.
  • Chest X-rayis done in order to rule out any other disease process and look for characteristic signs suggestive of COPD on X-ray.
  • Diffusing Capacity of Carbon Monoxide (DLco): Destruction of the alveolar walls decreases the diffusion of gases across it, which can be determined by measuring the amount of Carbon Monoxide (CO) transferred from the alveoli to the blood after the patient inhales a known amount of CO (0.1%). It helps establish the diagnosis of Emphysema and indicate its severity.
  • High Resolution C.T.Scan:It helps detect and quantify Emphysema It is the most sensitive and specific imaging technique and can detect emphysema in symptomatic patients with a normal chest X-ray.

Tests for Monitoring

  • Mini Peak-flow (PEFR) meterThis is a small and simple instrument which can be used by the patient at his / her house. The patient blows into the instrument and it gives an indication of the patient’s lung function (PEFR – Peak Expiratory Flow Rate). It can be useful in
    • Assessing patient’s daily condition.
    • As a warning to the patient (impending attack).
    • To check for the effect of the medicines given.

Corroborative tests

  • Blood counts are done to rule out any infection.
  • Sputum examination is done to look for any infective organisms in the phlegm of the patient.
  • Exercise test is done to determine the limit of safe exercise level that the patient can perform, without getting breathless.

Tests to assess Severity

  • ECG is done to detect any heart abnormality arising due to COPD.
  • Blood gas evaluation is done by taking a sample from the patient’s artery in the arm and measuring the various gas levels (oxygen and carbon dioxide).
  • Blood test for genetic defect (a1– antitrypsin deficiency gene typing) can be done to rule at an early onset of the disease in suspected individuals.