Progressive Care Nursing Certification (PCCN) Practice Exam

What initial ABG result should the nurse anticipate for a patient with a respiratory infection and shortness of breath?

1. Respiratory acidosis

2. Respiratory alkalosis

3. Metabolic acidosis

4. Metabolic alkalosis

The correct answer is: Respiratory alkalosis

In the context of a patient with a respiratory infection and shortness of breath, the initial arterial blood gas (ABG) result that is most likely to be anticipated is respiratory alkalosis. This is primarily due to hyperventilation that often occurs in response to shortness of breath or anxiety related to breathing difficulties. When a patient experiences increased respiratory effort, they may exhale more carbon dioxide than normal, leading to a decrease in arterial carbon dioxide levels. This decrease results in a rise in blood pH, characterizing respiratory alkalosis. Respiratory infections can initially cause irritation of the pulmonary system, leading to increased respiratory rate as the body attempts to compensate for reduced oxygenation or increased carbon dioxide levels. In the early stages, this compensatory mechanism can lead to a hyperventilatory state, further reinforcing the likelihood of respiratory alkalosis as an initial ABG result. Other potential ABG results like respiratory acidosis may appear later if the respiratory status deteriorates and hypercapnia occurs. Metabolic acidosis or metabolic alkalosis are generally not initial responses to respiratory infections and shortness of breath and are influenced by different pathophysiological processes.