Question

A 50-year-old man was admitted to the hospital with the diagnosis of chronic obstructive lung disease. On review of the chart, the nurse noted the patient is both hypoxic and has an elevated carbon dioxide level. When examining the patient, the nurse notes an increased respiratory effort and use of accessory muscles.

1. What is compliance, resistance, and residual volume as it relates to COPD.

2. In patients with chronic obstructive disease, there is a decreased surface area for diffusion. Explain how that will impact diffusion and how that relates to the hypoxia and elevated carbon dioxide.

3. Explain the difference between the function of the central and peripheral chemorecep

Answer 1

1. Lung compliance is a measure of the lungs ability to stretch and expand. In COPD loss of elastic recoil of the lung affects the pressure difference between the interior of the alveoli and pleural surface of the lung, that is the transpulmonary pressure. Transpulmonary pressure will cause greater or lesser expansion depending on compliance of lungs. As a result, in COPD lung compliance become higher, a lung of high compliance expand to greater extent.

Resistance - Airway resistance is the resistance of respiratory tract to airflow during inhalation and exhalation. Increase airway resistance seen in COPD. Increase airway resistance can be due to loss of elastic recoil due to change in lung tissue. It cause, destruction of the elastin and collagen fibres of the lung results in destruction of the alveoli. The air spaces become larger and the surface areas of gas exchange becomes much smaller. The reduced recoil tendency no longer holds open the bronchioles and so they tends to collapse, producing the increased airway resistance that characterize COPD.

Residual volume - volume of air remaining in the lung at the end of maximum expiration.

In COPD hyperinflation and gas trapping usually increase. Increased airway resistance, reduced lung recoil and shortened expiratory time through narrowed airway. In which the pleural pressure exceed Airway pressure by trapping air in the lung, result in pulmonary hyperinflation were patient residual volume get increased