Pathophysiology question about COPD

Question

A 62-year-old man with an 8-year history of chronic obstructive pulmonary disease (COPD) reports to the clinic with complaints of increasing shortness of breath, ankle swelling, and a feeling of fullness in his upper abdomen. The expiratory phase of his respiration is prolonged, and expiratory wheezes and crackles are heard on auscultation. His blood pressure is 160/90 mmHg, his RBC count is 6.0 x 106/µL (normal is 4.2-5.4 x 106/µL), his hematocrit is 65% (normal male value is 40-50%), his arterial PO2 is 55 mmHg and his O2 saturation, which is 85% while he is resting, drops to 55% during walking exercise.  

1. Explain the physiologic mechanisms behind his edema, hypertension, and elevated red blood cell count.  
2. His arterial PO2 and O2 saturation indicate that he is a candidate for continuous low-flow oxygen. Explain the benefits of this treatment in terms of his activity tolerance, blood pressure, and red blood cell count.

Any help with this question would be greatly appreciated! Thanks.

Answer 1

Hi! COPD damages the air sacs in the lungs and interferes with this process. If the damage reaches a critical point, a person may develop hypoxia. Hypoxia occurs when the blood does not deliver enough oxygen to the air sacs in the lungs. COPD can narrow and become fewer which can cause pulmonary hypertension. Peripheral edema (swelling in the arms or feet) is caused by pulmonary hypertension. Because the right side of the heart pumps blood into the lungs which then absorbs oxygen through the blood vessels and out through the left side of the heart and to the rest of the body, blood flow can become affected due to high blood pressure (hypertension). There is high blood pressure in his lungs which creates a harder time for the blood vessels in the lungs to pump blood in order to be oxygenated. This requires the heart to work harder creating his hypertension (160/90mmHG). This means that the right side of the heart is not pumping enough blood into the lungs resulting in the body not absorbing enough oxygen. With the rest of the body not receiving enough blood, organs like the liver and kidneys and lymphatic vessels cannot remove fluids from the body. This causes fluid to build up in the hands and feet. His increased red blood cell count is due to low blood oxygen which is a result of his hypertension and COPD. So because his airflow is obstructed, he is getting insufficient oxygen which increased the amount of red blood cells because they need more oxygen.

Low flow oxygen will be the best treatment for him. Blood oxygen levels drop only when he exercises so using oxygen during exercise may help boost performance and reduce shortness of breath. Constant flow of oxygen will help the body absorb more oxygen through the blood and reduce blood pressure as well as lower his RBC count.