To prevent deep vein thromboses following knee replacement surgery, an adult male client is receiving daily subcutaneous enoxaparin. Which laboratory result requires immediate action by the nurse?

Reference Range:
Hematocrit [42% to 52% (0.42 to 0.52 volume fraction)]
Platelets [150,000 to 400,000/mm² (150 to 400 × 10^9/L)]
Creatinine [0.5 to 1.1 mg/dL (44 to 97 μmol/L)]
Blood Urea Nitrogen (BUN) [10 to 20 mg/dL (3.6 to 7.1 mmol/L)]

Choice A reason: This statement indicates understanding of naloxone. Naloxone is an opioid antagonist that can reverse the effects of opioid overdose, such as respiratory depression, sedation, and hypotension. Naloxone can be administered by different routes, depending on the availability and urgency of the situation. Intravenous, intramuscular, and subcutaneous routes are all acceptable ways to give naloxone.

Choice B reason: This statement also indicates understanding of naloxone. Naloxone works best on pure agonist opioids, such as morphine, heroin, and fentanyl. These opioids bind to the same receptors as naloxone, but naloxone has a higher affinity and can displace them. Naloxone is less effective on partial agonist or mixed agonist-antagonist opioids, such as buprenorphine and pentazocine. These opioids have lower intrinsic activity or antagonize some receptors, making them less susceptible to naloxone.

Choice C reason: This statement indicates no understanding of naloxone. Naloxone is not a harmless drug that can be given repeatedly without consequences. Naloxone has a short half-life of about 30 to 90 minutes, which means it can wear off before the opioid does. This can cause the patient to relapse into respiratory depression and require repeated doses of naloxone. However, giving too many doses of naloxone can also cause adverse effects, such as agitation, hypertension, tachycardia, pulmonary edema, and seizures. Therefore, naloxone should be given cautiously and titrated to the minimum effective dose to reverse respiratory depression.

Choice D reason: This statement indicates no understanding of naloxone. Naloxone will affect the client's level of pain by blocking the analgesic effects of opioids. This can cause the patient to experience acute pain and distress, especially if they have a chronic pain condition or a surgical wound. Naloxone should not be used to treat opioid-induced sedation or pruritus without respiratory depression, as this will unnecessarily expose the patient to pain and suffering.

Choice E reason: This statement indicates no understanding of naloxone. When given IV, naloxone starts working immediately, but it does not last several hours. As mentioned earlier, naloxone has a short half-life and can be eliminated from the body quickly. The duration of action of naloxone depends on the dose, route, and frequency of administration, as well as the type, dose, and route of the opioid involved. Generally, naloxone lasts for about 30 to 90 minutes when given IV, which may not be enough to counteract the longer-lasting effects of some opioids. Therefore, continuous monitoring and repeated doses of naloxone may be needed until the opioid is cleared from the system.

Choice A reason: Platelet count of 100,000/mm³ (100 x 10^9/L) is below the normal range and indicates thrombocytopenia, which is a decrease in the number of platelets in the blood. Thrombocytopenia can increase the risk of bleeding and bruising, and can be a serious adverse effect of enoxaparin. This laboratory result requires immediate action by the nurse, such as notifying the prescriber, monitoring for signs of bleeding, and withholding the next dose of enoxaparin.

Choice B reason: Hematocrit 45% (0.45 volume fraction) is within the normal range and does not indicate any problem with the client's red blood cells or oxygen-carrying capacity.

Choice C reason: Blood urea nitrogen (BUN) 20 mg/dL (7.1 mmol/L) is within the normal range and does not indicate any problem with the client's kidney function or hydration status.

Choice D reason: Serum creatinine 1.0 mg/dL (88.4 μmol/L) is within the normal range and does not indicate any problem with the client's kidney function or muscle metabolism.