A nurse is reviewing the laboratory results of a client who received a dose of sodium polystyrene sulfonate. Which of the following labs should the nurse monitor to evaluate if the medication has been effective?

Morphine is an opioid agonistthat binds to mu-opioid receptors in the central nervous system to provide potent analgesia. Beyond pain relief, it exerts a depressant effecton the respiratory center and the autonomic nervous system, necessitating continuous monitoring of the patient's level of consciousness and hemodynamic stability.

Rationale:

A.Tachycardia is not a typical adverse effect of morphine; in fact, opioids tend to cause a decrease in heart rate or have no significant effect on it. Morphine reduces sympathetic outflow, which is more likely to result in bradycardia or a stable heart rate. The presence of tachycardia in a patient on a PCA pump might actually indicate inadequately controlled pain or a different underlying complication.

B.Sedation is a common and significant adverse effect of morphine that often precedes respiratory depression in patients using a PCA pump. The nurse must use a standardized scale to assess the client's arousal level, as excessive sleepiness indicates the drug is accumulating to potentially toxic levels. Monitoring for sedation allows the nurse to intervene early by adjusting the dose before life-threatening complications occur.

C.Hypotension occurs with morphine administration due to peripheral vasodilation and the release of histamine, which lowers systemic vascular resistance. This is particularly common when the drug is administered intravenously or in large doses via a PCA pump. The nurse must monitor blood pressure regularly and instruct the client to change positions slowly to prevent orthostatic hypotension and potential falls during therapy.

D.Hyperthermia is not an adverse effect associated with opioid analgesics like morphine. Morphine does not interfere with the thermoregulatory center in the hypothalamus in a way that would cause an elevated body temperature. If a patient receiving morphine develops a fever, the nurse should investigate other causes, such as an underlying infection or an inflammatory process, rather than attributing it to the medication.

E.Bradypnea, or an abnormally slow respiratory rate, is one of the most dangerous adverse effects of morphine because it directly depresses the brainstem respiratory centers. The nurse must count the client's respirations frequently and be prepared to administer naloxone if the rate falls below 8 to 10 breaths per minute. Bradypnea can lead to hypercapnia and respiratory arrest, making it a critical focus of PCA monitoring.

Hydromorphone is a potent opioid analgesicthat provides relief through the stimulation of mu-opioid receptorsin the central nervous system. A dangerous side effect is respiratory depression, where the drug decreases the responsiveness of brainstem respiratory centers to carbon dioxide levels.

Rationale:

A.Prednisone is a corticosteroid used for its anti-inflammatory and immunosuppressive properties. It has no pharmacological ability to reverse the central nervous system depression caused by opioid agonists like hydromorphone. Administering prednisone to a client with a depressed respiratory rate would provide no benefit in managing the immediate risk of respiratory failure or apnea.

B.Naloxone is an opioid antagonist that competitively binds to mu-opioid receptors, rapidly displacing opioid molecules like hydromorphone. It is the gold standard for reversing opioid-induced respiratory depression, restoring a normal breathing rate and level of consciousness within minutes. The nurse must monitor the client closely after administration, as the half-life of naloxone is shorter than hydromorphone.

C.Epinephrine is a catecholamine used in the treatment of anaphylaxis, cardiac arrest, and severe hypotension. While it can stimulate the cardiovascular system, it is not a reversal agent for opioid toxicity. Using epinephrine for a depressed respiratory rate would not address the underlying receptor-level blockade causing the decreased ventilation and could cause unnecessary cardiac strain.

D.Flumazenil is a benzodiazepine antagonist used specifically to reverse the effects of drugs like diazepam or midazolam. It does not bind to opioid receptors and therefore cannot reverse the respiratory depression caused by hydromorphone. The nurse must correctly identify the offending drug class to ensure the proper antagonist is selected for emergency intervention.