Page 41 - CASA Bulletin of Anesthiology 2021, Vol 8, No. 6 (1)

Vol. 8, No. 6, 2021

infusion, and found a significant difference in pain at 48 hours, but did not follow further. This
study gave a 0.4 mg/kg bolus. The other study gave 0.1 mg/kg followed by a 7 mg/kg/hr
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infusion and found significant relief during infusion.
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Post Herpetic Neuralgia

Weak Evidence, Grade D Recommendation1
4
There was only one trial that was double blind randomized. It involved 8 patients that either
received morphine at 0.075 mg/kg plus ketamine at 0.15 mg/kg or morphine plus saline.
Allodynia and wind up pain were significantly better in the groups that also received ketamine at
15 and 45 minutes after infusion. Due to the limited amount of trials, it is difficult to say
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whether ketamine will provide long-term relief for post herpetic neuralgia. This does however
support there is an NMDA mechanism that ketamine could help.

Fibromyalgia

Weak Evidence, Grade D Recommendation1
4
There are few trials on fibromyalgia that followed patient's long-term symptoms and one of
the few that did not show long-term relief. Four double blind RCTs found significant
improvements in pain during and immediately following infusion. Dosing ranged from 0.3
mg/kg to 0.5 mg/kg over 10 to 30 minutes. 23-26 In the study with long term follow-up 24 patients
received S-ketamine at 0.5mg/kg or 5 mg midazolam. They had immediate relief, but no
significant relief from 2.5 hours to 8 weeks.
26
Ischemic Pain from Severe Peripheral Vascular Disease

Weak Evidence, Grade D Recommendation1
4
There were two double blind RCTs, one in which ketamine was compared with morphine
showing no significant difference, and another where ketamine was compared with placebo
27
resulting in significant pain relief at day 1 and 5. In the latter study 35 patients received
morphine plus ketamine 0.6 mg/kg over four hours, or morphine and placebo. This supports
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ketamine as a good pain adjunct, as it is known for its analgesic properties, but does not
necessarily support its impact on central mechanisms to provide lasting relief for ischemic pain
patients.
Migraine Headache

Weak Evidence, Grade D Recommendation1
4
One two-part double blind RCT of 17 patients found significant improvements in pain. In the
first part 17 patients with acute migraine received 80 mcg/kg subcutaneous ketamine. In the
second part 17 patients with refractory migraine received 80 mcg/kg subcutaneous ketamine
three times a day versus placebo for three weeks. Both groups had significant relief, supporting
ketamine’s use as abortive and prophylactic therapy for migraines. 29
There is otherwise conflicting evidence for ketamine as abortive migraine therapy,
especially in the emergency department setting.

Complex Regional Pain Syndrome

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