Asthma and COPD Q 43

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A nurse plans care for a client with chronic obstructive pulmonary disease, knowing that the client is most likely to experience what type of acid-base imbalance?

  

     A. Respiratory acidosis

     B. Respiratory alkalosis

     C. Metabolic acidosis

     D. Metabolic alkalosis

    

    

Correct Answer: A. Respiratory acidosis

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Respiratory acidosis is most often due to hypoventilation. Chronic respiratory acidosis is most commonly caused by COPD. In end-stage disease, pathological changes lead to airway collapse, air trapping, and disturbance of ventilation-perfusion relationships. Respiratory acidosis is a state in which there is usually a failure of ventilation and an accumulation of carbon dioxide. The primary disturbance of elevated arterial PCO2 is the decreased ratio of arterial bicarbonate to arterial PCO2, which leads to a lowering of the pH.

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Option B: Respiratory alkalosis may be an acute process or a chronic process. These are determined based on the level of metabolic compensation for the respiratory disease. Acute respiratory alkalosis is associated with high bicarbonate levels since there has not been sufficient time to lower the HCO3 levels and chronic respiratory alkalosis is associated with low to normal HCO3 levels.

Option C: Metabolic acidosis is characterized by an increase in the hydrogen ion concentration in the systemic circulation resulting in a serum HCO3 less than 24 mEq/L. Metabolic acidosis is not a benign condition and signifies an underlying disorder that needs to be corrected to minimize morbidity and mortality.

Option D: Normal human physiological pH is 7.35 to 7.45. A decrease in pH below this range is acidosis, an increase over this range is alkalosis. Metabolic alkalosis is defined as a disease state where the body’s pH is elevated to greater than 7.45 secondary to some metabolic process.

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