Question

Discuss in detail chronic obstructive pulmonary disease (COPD).

• Compare and contrast chronic bronchitis and emphysema (include manifestations, etiologies, diagnosis and treatment).
• Describe the pathophysiology of COPD (include heart, kidney, respiratory muscle compensations, pH discussion, ventilation/perfusion mismatching)
• What is the significance of the central chemoreceptors in the brainstem in relation to the body's response to these conditions. Why may it be dangerous to give patients high flow oxygen?

Answer 1

Chronic bronchitis and emphysema often occur together and make up COPD. Smoking is a leading cause of both conditions. Both causes breathing problems

Emphysema is a lung condition where the air sacs or alveoli, become damaged,as a result tissues receive less oxygen, over time, emphysema weakens the alveoli and destroys the elasticity of pulmonary airways. as a result, emphysema sufferers experience shortness of breath and a constant struggle to breathe.If a person has a persistent cough that produces mucus for at least 3 months of the year for 2 years in a row, it may signal chronic bronchitis. Arterial Blood Gases Analysis can be done,these blood tests measure how well your lungs transfer oxygen to your bloodstream and remove carbon dioxide.There’s no cure for emphysema, but treatments are available to relieve symptoms and prevent further lung damage. Steroids can also be used to treat emphysema, your doctor may prescribe corticosteroids in an inhaler form. Corticosteroids relieve symptoms by reducing inflammation.Quit smoking.

Chronic bronchitis is a lung condition that destroys tiny hairs, called cilia, in the airways of the lungs. The airways then become inflamed and narrower, making breathing difficult, the lining of your bronchial tubes becomes inflamed or irritated. This can cause wet cough that lasts at least for few months.  If tests show stretched lungs or lungs that are larger in places than usual, a person may have emphysema, a blood test to look for signs of infection or a chest X-ray to see if your lungs and bronchial tubes look normal and rule out pneumonia.The goal of treatment for chronic bronchitis is to help you breathe better and control your symptoms. Your doctor may recommend healthy lifestyle changes such as quitting smoking; taking medicines to help clear your airways or to prevent symptoms from getting worse; or, in some cases, getting oxygen therapy to help you breathe better

Pathophysilogy of COPD.

COPD results from the combined processes of peripheral airway inflammation and narrowing of the airways. This leads to airflow limitation and the destruction and loss of alveoli, terminal bronchioles and surrounding capillary vessels and tissues. COPD patients have a reduced ability to exhale the carbon dioxide adequately which leads to hypercapnia (having too much CO2 in body) Chronic elevation of carbon dioxide over time leads to acid-base disorders and a shift of normal respiratory drive to hypoxic drive .Alveolar hypoventilation leads to an increased PaCO2 (ie, hypercapnia). The increase in PaCO2, in turn, decreases the bicarbonate (HCO3–)/PaCO2 ratio, thereby decreasing the pH, leading to respiratory acidosis. In severe cases of COPD, the condition can actually cause the development of right-sided heart failure. This occurs when low oxygen levels due to COPD cause a rise in blood pressure in the arteries of the lungs, a condition known as pulmonary hypertension. COPD can lead to V/Q mismatch. Alveolar dead space in COPD leads to inefficient gas exchange, which leads to a ventilation-perfusion mismatch. Patients with chronic obstructive pulmonary disease (COPD) have an increased risk of renal impairment and renal failure.

Central chemoreceptors of the central nervous system, are sensitive to the pH of their environment,Chemoreceptors are instrumental in the regulation of breathing. Blood concentrations of O₂ and CO₂ as well as serum pH need to be maintained within a narrow range to ensure normal function of the body’s tissues. In a condition like COPD there is increases CO2 levels in the body, An increase in arterial carbon dioxide levels indirectly stimulates central chemoreceptors  In COPD patients this effect is blunted as the chemoreceptors develop tolerance to chronically elevated arterial carbon dioxide level.

If too much oxygen is given in patients with COPD it can cause hypoventilation and dangerous levels of CO2 in body, hence it is very important that only optimum levels of oxygen to be given.