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The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans
Author(s) -
Persson J.,
Hasselström J.,
Wiklund B.,
Heller A.,
Svensson J.O.,
Gustafsson L. L.
Publication year - 1998
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1998.tb05317.x
Subject(s) - medicine , analgesic , ketamine , arteriosclerosis obliterans , anesthesia , morphine , neuropathic pain , visual analogue scale , dissociative , pharmacology , surgery
Background : Ketamine in sub‐dissociative doses has been shown to have analgesic and phantom‐Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain‐generating mechanisms are not well understood. Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub‐dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5‐min infusion on four separate days in a cross‐over, double‐blind, randomised protocol. Plasma levels of (S)‐ and (R)‐ketamine and their nor‐metabolites were analysed with an enantioselective high‐performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS). Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose‐dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side‐effects, mainly disturbed cognition and perception, were pronounced and dose‐dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg. Conclusion : We have demonstrated a potent dose‐dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.