A nurse is caring for a patient who has been receiving morphine via PCA pump following abdominal surgery two days ago and is scheduled to be switched to oral analgesics today.

The patient’s current settings are a demand dose of 1 mg, a lockout interval of 10 minutes, a four-hour limit of 30 mg, and a basal rate of 2 mg/hr.

The patient reports satisfactory pain relief with these settings and has received an average of 20 mg of morphine per four-hour period in addition to the basal rate over the past day.

The provider orders oxycodone/acetaminophen (Percocet) 5/325 mg PO every six hours PRN for pain, starting today at noon, and discontinues the PCA pump at that time.

What action should the nurse take?

The correct answer is choice B. Administer Percocet every six hours around the clock for two days.

This is because the patient has been receiving a continuous infusion of morphine via a PCA pump, which means that they have a steady level of opioids in their system.

If the PCA pump is discontinued abruptly and the patient is switched to oral analgesics PRN, they may experience withdrawal symptoms and inadequate pain relief.

Therefore, the patient needs to receive a scheduled dose of oral opioids for at least two days to prevent a sudden drop in opioid blood concentration and to maintain adequate analgesia.

After two days, the patient’s pain level and opioid requirement may be reassessed and the oral analgesics may be tapered or given PRN as needed.

Choice A is wrong because a higher dose of Percocet is not necessary if the patient reports satisfactory pain relief with the current PCA settings. The equivalent oral dose of morphine for the patient’s average PCA consumption is about 120 mg per day (20 mg x 6 doses), which is equivalent to about 80 mg of oxycodone per day (1.5 x 120 mg).

The prescribed dose of Percocet is 20 mg of oxycodone per day (5 mg x 4 doses), which is about 25% of the patient’s previous opioid requirement. This reduction is appropriate to account for incomplete cross-tolerance between different opioids.

Choice C is wrong because stopping morphine one hour before giving Percocet will not prevent a gap in analgesia. The half-life of morphine is about 2 to 4 hours, which means that it takes about 10 to 20 hours for morphine to be eliminated from the body.

Therefore, stopping morphine one hour before giving Percocet will not significantly reduce the morphine blood concentration and will not avoid the risk of additive effects or overdose.

Choice D is wrong because giving Percocet only if the patient reports breakthrough pain will not provide adequate pain relief for the patient who has been receiving a continuous infusion of morphine via a PCA pump.

The patient may experience withdrawal symptoms and increased pain sensitivity if the opioid blood concentration drops suddenly.

Therefore, the patient needs to receive a scheduled dose of oral opioids for at least two days to prevent a gap in analgesia and to allow a smooth transition from IV to oral opioids.