Certified Post Anesthesia Nurse (CPAN) Practice Exam

In a patient's ABG results showing pH = 7.25 and PCO2 = 50, what is the expected outcome of neuromuscular blockade?

1. Reversal of the effect of the block

2. Inhibition of the setup of the block

3. Increase in the level of the block

4. Prolongation of the duration of the block

The correct answer is: Prolongation of the duration of the block

The expected outcome of neuromuscular blockade in this scenario is that there would be a prolongation of the duration of the block. This is largely due to the acid-base status indicated by the arterial blood gas (ABG) results, particularly the low pH (7.25) and elevated carbon dioxide levels (PCO2 = 50). In an acidic environment, neuromuscular transmission can be altered. The low pH suggests a state of acidosis, which can increase neuromuscular blockade duration and intensity by affecting the neuromuscular junction. Acidosis can enhance the neuromuscular blocking effects of certain agents, as the muscle cells may become less responsive to the neurotransmitter released at the neuromuscular junction. Additionally, higher levels of carbon dioxide can lead to respiratory acidosis, further contributing to neuromuscular transmission impairment. Consequently, neuromuscular blockade may last longer and potentially require adjustments in dosing or timing for reversal agents, leading to the choice of prolongation of the block being the most appropriate outcome given the patient's ABG results.