A nurse is caring for a client who has COPD. The nurse should identify that the client is at risk for which of the following acid-base imbalances?
A.
Metabolic alkalosis
B.
Respiratory acidosis
C.
Respiratory alkalosis
D.
Metabolic acidosis
The Correct Answer and Explanation is:
The correct answer is B. Respiratory acidosis.
Explanation:
Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung condition that includes chronic bronchitis and emphysema. It is characterized by airflow limitation that is not fully reversible, which impairs the lungs’ ability to effectively exchange gases. This impaired gas exchange can lead to several acid-base imbalances, but respiratory acidosis is the most common in patients with COPD.
Respiratory Acidosis:
- Pathophysiology: Respiratory acidosis occurs when there is an accumulation of carbon dioxide (CO2) in the blood, leading to an increase in carbonic acid and a subsequent decrease in blood pH. In patients with COPD, the airflow limitation causes inadequate ventilation, preventing the effective removal of CO2 from the body. This CO2 builds up, leading to a rise in the partial pressure of CO2 (PaCO2) and a decrease in pH, hence resulting in respiratory acidosis.
- Symptoms: Patients with COPD may experience symptoms such as shortness of breath, confusion, headache, and lethargy, which are associated with elevated CO2 levels and decreased blood pH. These symptoms are indicative of respiratory acidosis and can be exacerbated during acute exacerbations of COPD.
- Compensation: The body attempts to compensate for respiratory acidosis through metabolic processes. Over time, the kidneys may retain bicarbonate (HCO3-) to buffer the excess acid and help normalize the blood pH. However, in acute exacerbations or advanced COPD, this compensation might be insufficient, leading to persistent acidosis.
- Management: Management of respiratory acidosis in COPD involves addressing the underlying cause—improving ventilation and oxygenation. This can be achieved through bronchodilators, corticosteroids, oxygen therapy, and in severe cases, mechanical ventilation.
Other Acid-Base Imbalances:
- Metabolic Alkalosis (A) and Metabolic Acidosis (D) are less commonly associated with COPD. Metabolic alkalosis typically results from loss of hydrogen ions or excess bicarbonate, not a primary feature of COPD.
- Respiratory Alkalosis (C) occurs when CO2 levels drop too low, usually due to hyperventilation. While COPD patients might hyperventilate occasionally, the primary concern in COPD is the retention of CO2 rather than its loss.
In summary, respiratory acidosis is the most prevalent acid-base imbalance in patients with COPD due to their impaired ability to expel CO2 effectively.