A nurse is caring for a client who is receiving meperidine. Which of the following is the nurse's priority assessment before administering the medication?

Choice A rationale Urinary retention is a potential adverse effect of opioid analgesics like meperidine due to their anticholinergic effects, which can relax the detrusor muscle and increase bladder sphincter tone. While important to monitor, it is not the most immediate life-threatening concern compared to respiratory depression. Choice B rationale Vomiting is a common gastrointestinal adverse effect of opioid analgesics, often due to stimulation of the chemoreceptor trigger zone in the brainstem. While distressing for the client and requiring intervention, it does not pose the immediate life-threatening risk that respiratory depression does. Choice C rationale Meperidine is an opioid agonist that acts on mu-opioid receptors in the central nervous system, including the brainstem respiratory centers. This can lead to dose-dependent respiratory depression by decreasing the sensitivity of these centers to carbon dioxide, making a depressed respiratory rate (normal range 12-20 breaths/min) the priority assessment for client safety. Choice D rationale Altered level of consciousness, such as drowsiness or sedation, is a common central nervous system effect of meperidine. While a significant finding indicating opioid effect, it is secondary in priority to respiratory depression, which directly impacts vital gas exchange and can quickly become life-threatening.