Chapter 28 Perioperative Nonopioid Infusions for Postoperative Pain Management

Question 1

Ketamine

Answer 1

a noncompetitive N-methyl-D-aspartate glutamate

receptor antagonist and a sodium channel blocker

Question 2

racemic ketamine

Answer 2

S(+) and R(–) stereoisomers. The S(+) ketamine has
four times greater affinity for the NMDA receptor than the
R(–) ketamine

Question 3

Ketamine half-life

Answer 3

80 to 180 min.

Question 4

Ketamine metabolite

Answer 4

norketamine has a longer half-life and is one-third as potent as the parent compound

Question 5

Effects of Ketamine

Answer 5

analgesic properties at low doses, It does not depress the laryngeal protective reflexes, does not suppress cardiovascular function in the
presence of an intact nervous system, causes less depression
of ventilation compared to opioids, and may stimulate
respiration.

Question 6

The analgesic effects of ketamine occurs at plasma concentrations of

Answer 6

100 to 150 ng.ml–

Question 7

undesirable characteristics of ketamine

Answer 7

postoperative malaise, accumulation of metabolites, development of tolerance, cardiovascular excitation, and the occurrence of psychotomimetic side effects

Question 8

beneficial effects of a low-dose ketamine

infusion

Answer 8

appears to improve the efficacy of epidural analgesia. It does not seem to have any effect when the anesthetic technique is total IV anesthesia where moderate amounts of intraoperative opioid are used.
IV ketamine may find its use as an adjunct in opioidtolerant
patients, or in patients with a higher incidence of chronic postsurgical pain such as thoracotomy, inguinal
herniorraphies, limb amputation procedures, or even
mastectomies

Question 9

Lidocaine peripheral and central effects suitable for the relief of pain.

Answer 9

Centrally, it has been shown to modify the neuronal responses in the dorsal horn and selectively suppress synaptic spinal transmission
by decreasing C-fiber–evoked activity in the spinal cord

Question 10

The beneficial effects of IV lidocaine infusion were not

duplicated in patients who had

Answer 10

total hip replacement or
coronary artery bypass graft surgery. The lack of beneficial effect of IV lidocaine infusion may not be evident when the surgical trauma is minimal as in ambulatory surgery or in surgeries where there is a moderate component of neuropathic pain such as in total hip surgery or in thoracic surgery.

Question 11

Benefit of IV lidocaine

Answer 11

The improved rehabilitation was supported by decreased postoperative pain at 24 hr after surgery, lower incidence of nausea and vomiting, and
shorter duration of ileus.

Question 12

IV lidocaine has been shown to attenuate the increased levels of proinflammatory cytokines which induce

Answer 12

peripheral and central nervous system sensitization leading to hyperalgesia

Question 13

IV lidocaine beneficial in what type of surgeries

Answer 13

Abdominal surgery

Pelvic: gynecologic, urologic

Question 14

Naloxone

Answer 14

a pure mu-receptor antagonist,

Question 15

Naloxone Effects

Answer 15

reversing the analgesia from the opioid. Naloxone
infusion has been utilized to decrease the incidence of
nausea, vomiting, respiratory depression, and urinary
retention after epidural and intrathecal opioids

Question 16

naloxone intravenous infusion

Answer 16

at 10 mcg.kg–1.hr–1 reduced the duration and quality of

analgesia from epidural morphine or fentany

Question 17

biphasic or dual modulatory effect of naloxone

Answer 17

small doses of naloxone produced analgesia while large

doses resulted in hyperalgesia.

Question 18

mechanisms of analgesic effect of naloxone

Answer 18

maybe related to the release of endorphins or displacement
of endorphins from receptor sites not pertinent to analgesia. another possibility although this upregulation phenomenon
has been demonstrated after prolonged naloxone infusion
(7 days). At higher doses, naloxone blocks the action of the released or displaced endorphin at the postsynaptic receptor.

Question 19

Naloxone half life

Answer 19

Naloxone has
an alpha half-life of 4 min and a beta half-life of 55 to
60 min

Question 20

indication for IV naloxone infusion

Answer 20

control the side effects of

neuraxial opioids.

Question 21

Benefit of wound infusions

Answer 21

reduce postoperative pain, diminish opioid intake and opioid-related side effects, and increase patient satisfaction

Question 22

effect of wound infusion after abdominal surgery

appears to depend on where the wound catheter is placed

Answer 22

Subcutaneous placement restricts the blockade of parietal nociceptive inputs to the superficial layer of the abdominal wall, while subfascial placements
block the fascia and peritoneum, which are richly innervated tissues

Question 23

Risk of wound infusion

Answer 23

A risk from the technique is
direct tissue toxicity such as myotoxicity,95 but this possibility
from subcutaneous, subfascial, or preperitoneal
local anesthetic infusions is rare.