Acute post-operative pain is common in the post-operative care unit (PACU). When conventional doses of opioid analgesics fail to bring acute postoperative pain under control the condition may represent acute opioid tolerance and hyperalgesia; patients undergo wind-up, central sensitization and experience opioid induced acute hyperalgesia resulting from activation of spinal NMDA receptors. The goal of our study was to determine if a combination of magnesium (1 gm), lidocaine (100mg), ketorolac (15mg) - MLK mixed together and administered in fixed dosage intravenously would reverse opioid tolerance and therefore provide pain relief. Each of the medications in the MLK combination has been independently shown to produce analgesia in the PACU. We believe the combination is synergistic and provides rapid reversal of the acute opioid tolerance. We performed an open label, non-randomized, IRB approved study at the LAC-USC Medical Center. We administered MLK to any patient in the PACU with postoperative pain levels >7/10 on the verbal analogue scale after having received 2 mg total dose of hydromorphone. Two sets of vital signs and VAS scores over 15mins each were obtained after administration of MLK. Patients who did not experience adequate analgesia (pain levels remaining >7/10 after MLK) were treated with additional opioids. Our aim was to determine if opioid resistant pain is more adequately treated by MLK. Our results showed that 80% (12/15) patients who received the MLK solution showed a significant and adequate pain relief to cross over from severe >7/10 pain to moderate <6/10 pain. The 3 patients that did not benefit from the MLK solution did not benefit from the additional opioid medication doses given to them either. This open label study merits further confirmation but our initial results are very promising. Our prospective, randomized double blinded study is in currently in progress.
© 2013 Published by Elsevier Inc.