Page 30 - CASA Bulletin of Anesthesiologisy 2022 9(6)-1 (3)

CASA Bulletin of Anesthesiology

as postoperative respiratory depression, hypoxemia, re-intubation and cardiac complications
including arrhythmias and prolonged QTc . Patients who received methadone treatment gain the
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most analgesic benefit between 48-72 hours postoperatively. In addition to opioid agonism,
methadone is also an NMDA antagonist that can be useful for opioid tolerance and hyperalgesia.
Other mechanisms include inhibition of 5-hydroxytryptamine and norepinephrine reuptake .
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Fentanyl

The fentanyl iontophoretic transdermal system (ITS) is another type of patient controlled
analgesic system that offers similar analgesic efficacy as IV PCA without the complications
associated with administering medications intravenously (ie. line occlusion, infections). The ITS
utilizes iontophoresis to administer medications transdermally and at pre-programmed doses.
The ITS eliminates the risks associated with administering medications intravenously such as
line occlusion and infections. Although ITS still requires skilled nursing monitoring, it is easier
to set up and trouble shoot compared to IV PCAs. Overall ITS formulation of fentanyl had less
opioid related complications including hypotension, tachycardia, hypotension, pruritus and
urinary retention. However, it was shown to be better than IV morphine PCAs in promoting early
mobilization following surgery .
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New therapeutic modalities for postoperative pain management continue to emerge.

TENS, Epidural Analgesia, ESPB

Transcutaneous electrical nerve stimulation (TENS) is another non-invasive technique that
can be used to relieve pain by transmitting electrical pulses to areas of pain. TENS is based on
‘ ’
impulses, thereby decreasing painful input to the central nervous system. Evidence behind the
analgesic efficacy of TENS in the perioperative period for postoperative pain control is unclear
but there are multiple studies demonstrating significant reduction in pain and pharmacological
analgesic consumption with its use .
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Epidural analgesia has shown to be effective for both intraoperative and postoperative
analgesia in a variety of surgeries including spine surgery. Epidural analgesia can provide
potential benefits including increased patient satisfaction, decreased opioid requirements, earlier
mobilization and decreased risk of postoperative nausea & vomiting. In a retrospective study
done at the Cleveland Clinic Foundation, epidural analgesia was shown to decrease opioid
requirements and their side effects, particularly in the elderly population 57, 58 .

Erector spinae plane blocks (ESPB) is a paraspinal interfascial nerve block where local
anesthetic is injected between the erector spinae muscles and the thoracic transverse processes to
target the ventral and dorsal rami of spinal nerves. A meta-analysis of 13 studies done on patients
receiving ESPB following spine surgeries have shown reduced total opioid use, better pain
scores and lower risk of postoperative nausea and vomiting with the use of ESPB. However, the
quality of pooled findings was judged to be low to moderate . In a study done by Avis et al.
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where 50 patients undergoing lumbar spine surgery were randomized to receive bilateral ESPB
with ropivacaine versus saline showed that there was no difference between the two groups in
opioid sparing effects and pain scores . None of these studies investigated the effect of
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continuous ESPB for postoperative analgesia which is an area that may be worth exploring.

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