Ketamine as an Adjunct to Postoperative Pain Management in Opioid Tolerant Patients after Spinal Fusions: A Prospective Randomized Trial

Abstract

Management of acute postoperative pain is challenging, particularly in patients with preexisting narcotic dependency. Ketamine has been used at subanesthetic doses as a N-methyl D-aspartate (NMDA) receptor antagonist to block the processing of nociceptive input in chronic pain syndromes. This prospective randomized study was designed to assess the use of ketamine as an adjunct to acute pain management in narcotic tolerant patients after spinal fusions. Twenty-six patients for 1-2 level posterior lumbar fusions with segmental instrumentation were randomly assigned to receive ketamine or act as a control. Patients in the ketamine group received 0.2 mg/kg on induction of general anesthesia and then 2 mcg kgfor the next 24 hours. Patients were extubated in the operating room and within 15 minutes of arriving in the Post Anesthesia Care Unit (PACU) were started on intravenous patient-controlled analgesia (PCA) hydromorphone without a basal infusion. Patients were assessed for pain (numerical rating scale [NRS]), narcotic use, level of sedation, delirium, and physical therapy milestones until discharge. The ketamine group had significantly less pain during their first postoperative hour in the PACU (NRS 4.8 vs 8.7) and continued to have less pain during the first postoperative day at rest (3.6 vs 5.5) and with physical therapy (5.6 vs 8.0). Three patients in the control group failed PCA pain management and were converted to intravenous ketamine infusions when their pain scores improved. Patients in the ketamine group required less hydromorphone than the control group, but the differences were not significant. Subanesthetic doses of ketamine reduced postoperative pain in narcotic tolerant patients undergoing posterior spine fusions.

Ketamine added to morphine or hydromorphone patient-controlled analgesia for acute postoperative pain in adults: a systematic review and meta-analysis of randomized trials

“…Supplementary 18,[20][21][22][25][26][27]29,30,32,34,36,40,41,44,45,50 cardiac or thoracic surgery (six trials), 19,23,35,37,38,53 orthopedic surgery (ten trials), 24,28,31,33,39,43,[47][48][49]51 and other surgery (three trials). 42,46,52 General anesthesia was used in 34 trials; one trial used PCA during and after a uterine artery embolization procedure, 29 and one used either general or regional anesthesia.…”

“…43 The target patients in one study were male opium abusers undergoing orthopedic surgery with morphine PCA for postoperative pain control, 24 and in another three studies, patients with chronic pain were managed with opioids preoperatively and with hydromorphone PCA for postoperative pain control. [46][47][48] Ketamine was administered via PCA in 26 trials, with a ketamine:morphine ratio of 1:1 ( (Supple mentary Table 2). …”

Why anesthesiologists need to care about the way chronic pain is managed

“…The patients who received low-dose ketamine on induction of general anesthesia and for the following 24 hr did not show statistically significant pain reduction during the first postoperative day, either at rest or with physical therapy, or reduced use of hydromorphone for pain control. 16 A recent meta-analysis shows that preemptive analgesia does have an effect on postoperative pain scores, supplemental analgesic consumption, and time to first analgesic consumption. Preemptive epidural analgesia probably has the greatest effect, while local anesthetics for wound infiltration and NSAID administration have a lesser effect.…”

“…Les patients ayant reçu une faible dose de kétamine à l'induction de l'anesthésie générale et durant les 24 heures suivantes n'ont pas montré de réduction statistiquement significative de la douleur durant le premier jour postopératoire, qu'ils soient au repos ou en traitement de physiothérapie, ou de réduction de leur utilisation d'hydromorphone pour soulager la douleur. 16 Une méta-analyse récente a montré que l'analgésie préventive a un effet sur les scores de douleur postopératoires, la consommation d'analgésiques supplémentaires et le moment de première prise d'analgésique. L'analgésie péridurale préventive a probablement l'effet le plus prononcé, alors que les anesthésiques locaux par infiltration de plaie et l'administration d'AINS ont un effet moindre.…”

Ketamine as an adjunct to patient-controlled analgesia: why, for whom, and how much?

“…16 N-methyl-D-aspartate receptors are implicated in the pathogenesis of these phenomena. Other groups of individuals who could benefit from administration of ketamine are those who have features of neuropathic pain 17 (e.g., patients undergoing spine surgery for axial and/or radicular pain) 18,19 or those who have a history of significant adverse effects (e.g., PONV) from opioids. We should also consider using ketamine for individuals who are likely to develop persistent postoperative pain (PPP) of neuropathic etiology.…”