COPD

What is it?

COPD (chronic obstructive pulmonary disease) consists of either one or a combination of  two types, chronic bronchitis and or emphysema. In either case, air is obstructed from leaving the lungs upon expiration, leading to a build up of CO2, and over inflation of the alveoli.

Chronic Bronchitis

Chronic Bronchitis, is often the result of chronic tobacco use, most specifically smoking, as it paralysis the cilia in the upper airway. The Trachea, and Primary Bronchus produce mucus which collect bacteria in the airway, which in turn is moved upward by the cilia to be expelled. Roughly 1L of mucus is produced each day. Apart from obstructing the airway, mucus collection often times leads to chronic infections, which in turn leads to increased inflammation, and an even smaller airway.

Emphysema

Emphysema is also primarily brought on by smoking, or a polluted air source. As the airway becomes irritated, inflammation occurs which produces a substance known as “Elastase” which breaks down elastic fibers in the lungs. These elastic fibers are what are needed to help pull open the airway and alveoli during inspiration. Over time the airway is unable to remain open for as long as is needed to expel all of its CO2. This means that on the next inspiration, the alveoli are already partially filled, and as more air enters, they become distended. These distended alveoli have a reduced surface area, which leads to a decreased ability to transfer what little oxygen that is being brought in, into the bloodstream.

B2 & M Receptors

Our airway consists of a series smooth muscles which consist of Beta-2 and M receptors. When B2 receptors are activated, the smooth muscles relax, and when M receptors are activated they contract. This is key to understanding medications used in treating COPD.

Symptoms
  • Shortness of breath
  • Cough / Sputum
  • Barrelled chest
  • High CO2 retention
Pulmonary Function Test

Have the patient breathe into a spirometer, and expel as much air as they can over roughly 6-10 seconds. This is known as the FVC (forced vital capacity). Next have the patient breathe into the spirometer, and expel as much air as they can in one second. This is known as the FEV1 (Forced Expiratory Volume). Next divide FEV1 / FVC, if the number is less than 0.70 they meet the criteria for COPD.

Labs
  • Arterial Blood Gas (ABG)
Imaging
  • CT Scan
  • Chest X-Ray
Treatment
  • Beta-Agonists
    • Albuterol (short acting)
    • Serevent (long acting)
    • Foradil and Perforomist (long acting)
  • Muscarinic antagonist
    • Atrovent (short acting)
    • Spiriva (long acting)
    • Tudorza (long acting)
  • Inhaled Steroids
    • Advair
    • budesonide
  • Oxygen Therapy
    • PaO2 <55 mmHg / 60 for pulmonary hypertension
    • SaO2 <89% /90 for pulmonary hypertension