Certified Post Anesthesia Nurse (CPAN) Practice Exam

Given the ABG results of a patient on a ventilator (pH = 7.24, PCO2 = 56, SaO2 = 91%), what action does the perianesthesia nurse anticipate?

1. Increasing the PEEP and the RR

2. Decreasing the PEEP and FiO2

3. Increasing the Vt and decreasing the RR

4. Increasing the Vt and the RR

The correct answer is: Increasing the Vt and the RR

The identified answer points to an appropriate response in the context of the patient's ABG results, which exhibit a low pH and elevated PCO2. A pH of 7.24 indicates acidosis, and a PCO2 of 56 signifies hypercapnia, meaning the patient is retaining carbon dioxide. This situation can often result from inadequate ventilation. Increasing both the tidal volume (Vt) and the respiratory rate (RR) serves to enhance the patient's ventilation, allowing for the expulsion of excess CO2 and subsequently helping to correct the acid-base imbalance. By increasing the tidal volume, more air—and therefore more CO2—can be cleared with each breath. Additionally, increasing the respiratory rate further facilitates CO2 elimination by increasing the total number of breaths taken over a given time period. In contrast, the other options do not adequately address the underlying issue of CO2 retention. Increasing PEEP without addressing the inadequate ventilation may not provide a solution, as it could potentially further limit the expiratory phase. Decreasing PEEP and FiO2 would not aid in resolving the hypercapnia, and likewise, increasing Vt while decreasing the RR would be counterproductive, as it would reduce the frequency of breaths, potentially maintaining elevated CO2