A nurse is administering hydromorphone to a client who is experiencing postoperative pain. Which of the following findings is an adverse effect of this medication?

A. Tachypnea: Opioids such as hydromorphone depress the respiratory center in the medulla, leading to slowed respiratory rate rather than increased breathing. Respiratory depression is a key concern, not tachypnea. An elevated respiratory rate would suggest pain or anxiety rather than an opioid effect. B. Dilated pupils: Opioids characteristically cause miosis due to stimulation of the oculomotor nucleus. Pupil dilation is more commonly associated with stimulant use or hypoxia. This finding does not align with the expected neurologic effects of hydromorphone. C. Urinary retention: Hydromorphone increases sphincter tone and decreases bladder detrusor muscle contractility through central and peripheral opioid receptor activation. This interferes with normal voiding and can lead to urinary retention, particularly in postoperative or older adult clients. Monitoring urinary output is an important nursing consideration. D. Hypertension: Opioids more commonly cause vasodilation and hypotension due to histamine release and decreased sympathetic tone. Elevated blood pressure is not a typical adverse effect of hydromorphone. Changes in blood pressure usually trend downward rather than upward.