The Rise of Chronic Obstructive Pulmonary Disease

Like everywhere else in the world, India is changing – not only in terms of its demographics, urbanization, economic profile, and pollution but also in terms of its health burden, disease pattern, dominant-disease composition, morbidity, and mortality.

Traditionally, Chronic Obstructive Pulmonary Disease (COPD) has been considered an overlapping of two principle conditions: emphysema and chronic bronchitis. Emphysema is defined as either histopathological or radiographical by the loss of lung parenchyma and abnormal enlargement of air spaces without associated fibrosis, whereas chronic bronchitis is defined clinically as the presence of a productive cough for at least three consecutive months in two consecutive years. Over the past decade, further refinements in the constellations of symptoms defining various groups of patients with COPD have been developed. These clinical groupings are called COPD phenotypes and they are believed to assist with the prediction of clinical course and optimal therapies.

According to the WHO world health statistics report 2016, chronic obstructive pulmonary disease (COPD) killed 1,061,900 people which were 10.8 per cent total deaths. India is experiencing a continued increase in COPD, with an estimated prevalence of more than 57,000,000 people suffering from obstructive airway diseases (OADs) by the end of 2016.

In early COPD, the major causes of death are lung cancer and cardiac disease, whereas, in more advanced COPD, respiratory failure is the major cause of mortality. During acute exacerbations of COPD, the leading causes of death are heart failure (37.2%), pneumonia (27.9%), pulmonary thromboembolism (20.9%), and respiratory failure (14%).

RISK FACTORS FOR COPD

The single most significant risk factor for the development of COPD is tobacco smoke inhalation. Factors that influence the development of COPD include the age at the start of smoking, amount, type of tobacco product consumed, the age of quitting, and the length of smoking cessation. The prevalence of COPD has generally followed the prevalence of tobacco smoking; with a lag time of approximately 20-30 years. Whereas only 20-50% of all smokers develop COPD, approximately 75-90% of all individuals with COPD have been or are smokers. Other factors that may be associated with the development of COPD include indoor and outdoor air pollution; occupational exposures to gasses, dust, and fumes, and respiratory infections such as tuberculosis and human immunodeficiency virus.

Biomass (Solid Fossil) fuels are now considered a major cause of COPD and could be the single most common cause of COPD in the world.  In India, 70% of the homes use biomass fuel for cooking and heating purposes in poorly ventilated kitchens and the amount of particulate matter pollution generated by the burning of biomass fuel is extremely high. Ninety percent of rural households and 32% of urban households cook their meals on a biomass stove.  With only 25% of the cooking being done with cleaner gasses. Exposure to biomass smoke thus becomes a major risk factor for COPD in India. Mosquito coils and DoopBati used in homes to get rid of mosquitoes are other sources of exposure in Indian homes; burning of one mosquito coil at night is capable of emitting particulate matter equivalent to those of around a 100 cigarettes.


SIGNS AND SYMPTOMS

Pulmonary: Breathlessness, cough, and sputum production are the three major symptoms of COPD. Initially, there may be subtle changes such as an inability to maintain the pace when walking with peers or increased sensation of breathing while doing routine activities which gradually progresses to impede routine daily activities.

Extra-pulmonary manifestations: Over the past decade, COPD has been recognized to be more than just a pulmonary disorder; inflammation is postulated to be the pathophysiologic process linking pulmonary and no pulmonary manifestations of COPD. This multisystem involvement is believed to be due to inflammatory cytokines produced within the lungs and released into the circulation or inflammatory cells that are activated within the lungs and then enter the circulation for distribution throughout the body.

These non-pulmonary manifestations include cardiac, cerebrovascular, oncologic, musculoskeletal, hematologic, endocrine, and psychological disorders. The prevalence of ischemic cardiovascular disease among individuals with COPD is more than twice the level found among smokers who do not have COPD.

Non-pulmonary processes cause significant morbidity and mortality in COPD. Increased awareness, detection, and management of these manifestations of COPD have the potential to improve survival, reverse morbidity, improve the quality of life, and reduce healthcare utilization among patients with COPD. At present, there is no evidence that current pharmacologic treatments for COPD are effective treatments for COPD’s non-pulmonary manifestations.

Diagnostic Testing

SPIROMETRY: Because COPD is a syndrome, there is not a single objective criterion for its diagnosis. Although pulmonary physiologic measurement of airflow limitation was previously required for the diagnosis of COPD and remains the most commonly applied diagnostic standard; recent evidence shows that some individuals with radiographic evidence of emphysema may not have demonstrable obstruction during spirometric testing. Therefore, physiologic demonstration of obstruction is a critical but not essential factor in the diagnosis of COPD, especially emphysema.

The two key spirometric measurements are the amount of air expelled in the first second (FEV1), and the total amount of air exhaled (FVC). The spirometer also calculates the FEV1: FVC ratio, which is used to diagnose airflow obstruction or limitation. Normally, this ratio is approximately 80% (four-fifths of a vital capacity can be exhaled within the first second of exhalation). With obstruction, the FEV1: FVC ratio is reduced. The two most common thresholds for the definition of airflow limitation are an absolute value of FEV1/FVC < 0.7 or the lower limit of normal, the fifth percentile of the distribution of the FEV1/FVC ratio in a nonsmoking population with no clinical evidence of lung disease. As individual’s age, the ratio of FEV1: FVC decreases.

IMAGING: The most common imaging tests for the evaluation of COPD are the chest radiograph and computed tomography (CT) scan. Common chest radiographic manifestations of COPD include lung hyperinflation that manifests as enlarged lung fields, flattened diaphragms (best seen on the lateral view), increased retrosternal airspace, and caudal movement of the mediastinum with inferior displacement of the heart. Emphysema may cause effacement of the vascular markings and cause cysts or bullae. CT scans are more sensitive than chest radiographs for detecting the presence of emphysema and may be used to quantify lung parenchymal destruction, air trapping, and hyperinflation. CT scans are also useful in the diagnosis of bronchiectasis and more recently, have been used to measure airway luminal diameter and wall thickness that may be increased in chronic bronchitis

 

Management

The mainstays of COPD pharmacologic management are anticholinergics, bronchodilators (short, long and ultra-long-acting) and inhaled corticosteroids. Short-acting beta-agonists are usually the initial bronchodilator and should be prescribed on an as-needed basis as a rescue medicine. Nebulizers are an alternative to metered-dose inhalers (MDI) and Dry powder inhalers (DPI) when patients are seriously ill or unable to use them properly.

Other medications for the treatment of COPD include phosphodiesterase inhibitors, macrolides, and mucolytics. Phosphodiesterase inhibitors include methylxanthines such as theophylline or aminophylline, which are rarely used due to their narrow therapeutic window and frequent side effects and medication interactions. The specific phosphodiesterase 4 inhibitor, roflumilast, is approved by the FDA for the reduction of COPD exacerbations in individuals with chronic bronchitis and frequent exacerbations. Macrolides, such as erythromycin and azithromycin, have anti-inflammatory properties in addition to antimicrobial effects. Recent studies have shown that either daily erythromycin or azithromycin decreases the frequency of COPD exacerbations in patients with a history of exacerbations.Mucolytics such as n-acetylcysteine and carbocysteine may reduce COPD exacerbations and improve health-related quality of life in patients with COPD.

Supplemental oxygen improves survival in patients with hypoxemia at rest (PaO2 < 55 mmHg or SpO2 < 88%; or PaO2 < 60 and > 55mmHg with evidence of cor pulmonale). Smoking cessation is the singularly most important intervention for the prevention and treatment of COPD. Even after initially quitting, many smokers return to smoking; Half of all individuals who are able to quit smoking for at least 6 months will resume smoking within 8 years of quitting. Thus, the process of smoking cessation is often a series of episodes of quitting and relapses before permanent abstinence is achieved.

GOLD (Global initiate for chronic obstructive lung disease) guidelines:

  • Doctors should suspect COPD in anyone with shortness of breath, chronic cough, and/or a history of cigarette smoking.
  • Doctors should recommend pulmonary function testing to people who meet these COPD criteria.
  • Quitting smoking, and continued smokingabstinence are absolutely essential for anyone with COPD.
  • Inhaled corticosteroids may be recommended for people with severe COPD with frequent exacerbation episodes. Oxygen may be needed for those with very severe COPD.
  • Treatments should mainly consist of bronchodilators: inhaled medicationthat improves breathing.
  • Treatments should be individualized; each person should use a drug or combination of drugs that work for him or her.
  • Patients with severe COPD may require long-term oxygen therapy (LTOT) and bi-level positive airway pressure (BIPAP) devices to maintain oxygen saturation for optimal functioning of the diseased body.

Conclusion

COPD is a chronic, incurable but very treatable condition that is currently the third leading cause of death in the world. COPD is a syndrome composed of historical factors, clinical signs and symptoms, and physiologic and imaging abnormalities. Classically, COPD has been classified as emphysema, chronic bronchitis, or a mixed process; more recent studies suggest that there are many more clinical groupings or phenotypes that may have prognostic and therapeutic implications. Additionally, COPD is now recognized to be a multi-systemic disorder with a myriad of non-pulmonary manifestations, including cardiovascular, hematologic, endocrine, metabolic, and psychosocial derangements. Although there is no single diagnostic test for COPD, most individuals with COPD have airflow obstruction on spirometric testing and exhibit lung parenchymal and airway abnormalities on radiographic imaging. Over the past decade, the treatment of COPD has migrated from therapeutic nihilism to multiple effective medications that reduce respiratory symptoms, improve the quality of life, and improve survival.

 

Dr. Abhinav Sharma

Associate Consultant

Department of Interventional Pulmonology, Allergy, Immunology, Sleep Medicine and Critical Care

Shri Mata Vaishno Devi Narayana Superspecialitity Hospital, Kakryal

 

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