American Society of Regional Anesthesia and Pain Medicine February 2018 - 36

of the medication and isolate its block-related effect. Additives may
improve the block's quality, onset time, duration, or performance
(ie, motor block). Opioids added to IVRA may improve tourniquet
pain and onset time modestly; these benefits are generally not
outweighed by the significant occurrence of nausea, vomiting,
and sedation at tourniquet
deflation.13 Recent interest
in the use of tramadol and
sufentanil as adjuncts in
IVRA is inspired by the local
anesthetic-like properties
of both drugs; indeed, both
agents seem to shorten
the onset of sensory block.
However, neither appears
to confer significant
postoperative analgesic
benefits. The addition of nondepolarizing muscle relaxants may
improve motor block and in combination with fentanyl may result
in acceptable blockade at a reduced dose of local anesthetic. This
benefit, however, is offset by the potential for increased sensory
block onset time. Furthermore, the theoretical analgesic benefit
of muscle relaxants added to IVRA solutions (through reduction in
muscle spasm) has not been convincingly shown.12

mg added to plain lidocaine 3 mg/kg shortens block onset and
improves postoperative analgesia in some small studies,19 and this
effect may be magnified by the addition of other additives such as
ketorolac.16 The addition of ketamine to the block solution improves
postoperative and intraoperative analgesic requirements20;
however, this effect seems
to be no different than with
systemic administration.21
The addition of potassium22
confers no advantages, and
changing the temperature
of the injectate does not
affect the quality of the
block, although warmer
solutions are less painful
on injection.23

"Intravenous regional anesthesia is one
of the oldest anesthetic techniques still
in use today. More than 100 years of
experience attest to its safety and utility
in a wide variety of procedures."

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) as
adjuncts for IVRA has been widely studied. A review by Choyce and
Peng in 2002 summarized the state of the literature at that time,
with ketorolac shown to reduce postoperative pain after IVRA.13
However, the subsequent retraction of several articles published
regarding NSAIDs and acute pain have clouded the picture.14 Recent
studies have indirectly addressed that question by investigating the
use of additional adjuvants. Two of those studies have associated
ketorolac with postoperative pain and analgesic requirements when
added to the IVRA solution compared with lidocaine alone but did
not include a systemic administration control group.15,16
Clonidine and dexmedetomidine have also been added to IVRA
solutions with mixed results. Clonidine may increase tourniquet
tolerance time and modestly reduce postoperative pain scores, but
sedation and hypotension after tourniquet release are significant
adverse effects.13 Dexmedetomidine is more selective for alpha-2
receptors than clonidine, which accounts for its preferential
sedative over hemodynamic effects. At doses of 0.5-1 μg/kg added
to lidocaine, dexmedetomidine improves postoperative analgesia
and may shorten sensory block onset time.17,18 Importantly,
hemodynamic changes (bradycardia, hypotension) may still occur
with dexmedetomidine but seem less severe than with clonidine.
A wide variety of other additives have been studied to improve
IVRA, although most studies are small and often limited by the
lack of a systemic control group. Dexamethasone in a dose of 8

SUMMARY
Intravenous regional anesthesia is one of the oldest anesthetic
techniques still in use today. More than 100 years of experience
attest to its safety and utility in a wide variety of procedures. Recent
investigations have sought to improve the technique via lower doses
of local anesthetic with more distal tourniquets, the use of longeracting local anesthetics (ropivacaine), and the addition of other
medications (eg, dexmedetomidine) to the block solution. As always,
vigilance, careful patient selection, consideration of comorbidities,
and case-by-case individual assessment by a skilled anesthesiologist
are necessary to ensure optimal outcomes.
REFERENCES
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Holmes C. Intravenous regional analgesia: a useful method of producing
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Brill S, Middleton W, Brill G, Fisher A. Bier's block: 100 years old and still going
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10. Heath ML. Deaths after intravenous regional anaesthesia. BMJ
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American Society of Regional Anesthesia and Pain Medicine
2018

Table of Contents for the Digital Edition of American Society of Regional Anesthesia and Pain Medicine February 2018