Chapter 68. Intravenous Patient-Controlled Analgesia
Which statement is correct regarding the site of action of opioids?
A. The mechanism of action for opioids is only via the mu-receptors of the central nervous system.
B. Pure agonists are the most useful for acute pain.
C. Agonist-antagonist opioids act as a kappa antagonist and a mu-receptor agonist.
D. Partial agonists have a major role for analgesia.
B is correct. Pure agonists are the most useful for acute pain because of their complete mu binding.
A is incorrect. They also act via receptors in the peripheral nervous system.
C is incorrect. Agonist-antagonist opioids act as a kappa agonist and mu-receptor antagonist.
D is incorrect. Because they only have partial mu-receptor binding, pure agonists have a significant ceiling effect.
Which statement is correct regarding patient-controlled analgesia (PCA) for acute post-operative management?
A. Morphine is the best analgesic for PCA.
B. In at least 0.5% of the cases, PCA gives respiratory depression.
C. The fentanyl patch has a comparable effect to PCA, and therefore is a good choice in acute pain.
D. PCA is cost-effective through savings on nursing costs.
D is correct. It does reduce demand on the nursing staff, who are required for delivery of IV or IM PRN analgesics. This reduced workload of the nursing staff may indeed have a cost benefit. There is no apparent decrease in cost.
A is incorrect. There is no standard opioid. Patient characteristics will influence choice of opioid.
B is incorrect. All side effects together are less than 0.5%.
C is incorrect. Patches have a good indication for chronic cancer pain but none in acute pain.
Which statement is true regarding improving patient-controlled analgesia (PCA) effect?
A. Nonsteroidal anti-inflammatory drugs (NSAIDs), cyclo-oxygenase (COX)-2 inhibitors, and acetaminophen all have an opioid-sparing effect.
B. NSAIDs, COX-2 inhibitors, and acetaminophen reduce opioid-induced side effects.
C. Ketamine infusions should be avoided perioperatively because of the increased risk of hallucinations.
D. Association of lidocaine has an opioid-sparing effect.
A is correct. Several meta analyses suggest that the use of nonsteroidal anti-inflammatory drugs (NSAIDs), cyclo-oxygenase (COX)-2 inhibitors, and acetaminophen all have an opioid-sparing effect.