A single infusion of intravenous ketamine improves pain relief in patients with critical limb ischaemia: results of a double blind randomised controlled trial

We report the first double blind randomised controlled trial of regular opioids and an infusion of low dose (0.6 mg/kg) intravenous ketamine compared with opioids and placebo in patients with allodynia, hyperalgesia and hyperpathia secondary to critical limb ischaemia. Thirty-five patients completed the study, 18 received regular opioids plus ketamine, while 17 received regular opioids plus placebo. Using the Brief Pain Inventory, the % pain relief that the patients in the ketamine group attributed to their medication improved significantly from 50% immediately pre-infusion to 65% 24 h post-infusion and 69% 5 days post infusion. Over the same period, the pain relief achieved by the placebo group rose from 58% pre-infusion to 56% 24 h post infusion and then 50% relief 5 days later. This was statistically significant (P