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Chronic Obstructive Pulmonary Disease


Chronic Obstructive Pulmonary Disease overview and Definition

It is a respiratory problem which results in difficulty in breathing for indivduals. It results in airflow limitation that is only partially reversible. It is an abnormal response of the lung to the inflammatory process due to the noxious particle or gases.


Pathophysiology

Chronic obstructive pulmonary disease is characterized by chronic inflammation throughout the airways, parenchyma and pulmonary vasculature. Macrophages and T-lymphocytes (CD+8) and neutrophils are increased in the various part of the lungs. Activated inflammatory cells releases a variety of mediators such as leukotriene B4 , interleukin 8, tumor necrosis factor alpha  and others capable of damaging the lung structures. In addition to the inflammation an imbalance between the proteinases, antiproteases and oxidative stress plays an important role in the pathogenesis of chronic obstructive pulmonary disease.

Proteases: Antiprotease hypothesis holds that destruction of alveolar walls in emphysema is due to an imbalance between the proteases and their inhibitors in the lung.

In alpha 1 antitrypsin deficiency: A major protease inhibitor. Emphysema develops at a younger age especially in smokers. Impaction of the smoke particles into the bronchioles leads to the inflammatory cell aggregation , increased elastase activity and decreased alpha 1 antitrypsin activity resulting in centriacinar emphysema seen in smokers.

Chronic bronchitis:

This is a condition associated with excessive tracheobronchial mucus production sufficient to cause cough with expectoration on most days for atleast 3 months a year for more than 2 consecutive years. It can be subdivided into

Simple chronic Bronchitis(describes a condition with mucoid sputum production)

Chronic mucopurulent bronchitis(persistent or recurrent purulent sputum production in the absence of local suppurative disease)

Chronic bronchitis with obstructive or chronic asthmatic bronchitis(severe dyspnoea and wheezing in association with inhaled irritants or infections in the setting of bronchitis)

Emphysema:

It is defined as the distension of the air spaces distal to the terminal bronchitis  with destruction of the alveolar septa.

Types:

Centriacinar emphysema: there is the destruction and enlargement of central or proximal part of respiratory unit- the acinus. There is predominant involvement of upper lobe and apices. It is commonly seen in male smokers in association with chronic bronchitis.

Paraseptal emphysema: This involves only the distal acinus. It is found near the  pleura and often causes spontaneous pneumothorax.

Irregular: There is a irregular type of acinus a with scarring involvement.

Panacinar emphysema: there is uniform destruction and enlargement of acinus. It is predominant in lower basal zones. It is associated with alpha 1 antitrypsin deficiency.

 


Clinical signs & symptoms

  • Frequent coughing that produces a lot of mucus.
  • Wheezing
  • A whistling or squeaky sound when you breathe
  • Shortness of breath, especially with physical activity
  • Tightness in your chest
  • Cough


Differential Diagnosis

The most effective and common method for diagnosing COPD is spirometry. It is also known as pulmonary function test or PFT. This easy, painless test measures lung function and capacity.

To perform this test, you’ll exhale as forcefully as possible into a tube connected to the spirometer, a small machine. The total volume of air exhaled from your lungs is called the forced vital capacity (FVC).

The percentage of the Forced vital capacity  forced out in the first second is called the FEV1. FEV stands for forced expiratory volume. The maximum speed at which you empty your lung is called the peak expiratory flow rate(PEFR)

Spirometry reveals the efficiency of the lung muscles that are used in the inspiration and expiration process.

Bronchodilator reversibility test:

This test combines spirometry with the use of a bronchodilator which is the medicine to help open up your airways.

Initially, the standard spirometry test is used to get a baseline measurement of how well your lung are working. Then after about 15 minutes, the dose of bronchodilator medication and repeat the spirometry test.

Blood test:

Blood test reveals whether the symptoms are being caused by an infection or some other medical condition. An arterial blood gas test will measure the levels of oxygen and carbon dioxide in your blood. This is one of the indication of how well your lungs are working. This measurement can indicate how severe ypur COPD is and whether you may need oxygen therapy.

Genetic testing:

The doctor might check the levels of alpha 1 antitrypsin. This protein aids in the protection of the lung from inflammation caused by irritants such as pollution or smoking. It is produced by liver and then it is released into the bloodstream. With the help of the genetic deficiency alpha 1 antitrypsin can be detected. This test is harmless.

Chest x ray and CT scan:

A CT scan is a type of X ray that creates a more detailed image than a standard x ray. Any type of X ray might give the detailed pictures of structures inside your chest, including the heart lungs, and blood vessels.

Sputum examination:

Sputum is the mucus that is released when a person coughs.Sputum examination is indicated if you have a productive cough.

Analysing the sputum can help to identify the cause of the breathing difficulties and may help to detect the lung cancer.

Coughing enough to produce a sputum sample may be uncomfortable for a few moments. Otherwise, there are no real risks or downsides to a sputum examination. It can be very helpful in diagnosing your condition.

Electrocardiogram:

This helps to determine if your shortness of breath is being caused by a heart condition as opposed to a lung problem.

Over time, though, the breathing difficulties associated with COPD can lead to cardiac complications including abnormal heart rhythm and heart failure, and heart attack.

An EKG measures the electrical activity in your heart and can help diagnose a disturbance in your heart rhythm.


Prevention

Quit smoking

Reduce the exposure to the chemical irritants

Reduce the exposure to allergen

Quit the second hand smoking

Carry the inhalational steroid if you have the symptoms.