Adjuvant Analgesic Use in the Critically Ill: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis addresses the efficacy and safety of nonopioid adjunctive analgesics for patients in the ICU. We searched PubMed, Embase, the Cochrane Library, CINAHL Plus, and Web of Science. Two independent reviewers screened citations. Eligible studies included randomized controlled trials comparing efficacy and safety of an adjuvant-plus-opioid regimen to opioids alone in adult ICU patients. We conducted duplicate screening of citations and data abstraction. Of 10,949 initial citations, we identified 34 eligible trials. These trials examined acetaminophen, carbamazepine, clonidine, dexmedetomidine, gabapentin, ketamine, magnesium sulfate, nefopam, nonsteroidal anti-inflammatory drugs (including diclofenac, indomethacin, and ketoprofen), pregabalin, and tramadol as adjunctive analgesics. Use of any adjuvant in addition to an opioid as compared to an opioid alone led to reductions in patient-reported pain scores at 24 hours (standard mean difference, -0.88; 95% CI, -1.29 to -0.47; low certainty) and decreased opioid consumption (in oral morphine equivalents over 24 hr; mean difference, 25.89 mg less; 95% CI, 19.97-31.81 mg less; low certainty). In terms of individual medications, reductions in opioid use were demonstrated with acetaminophen (mean difference, 36.17 mg less; 95% CI, 7.86-64.47 mg less; low certainty), carbamazepine (mean difference, 54.69 mg less; 95% CI, 40.39-to 68.99 mg less; moderate certainty), dexmedetomidine (mean difference, 10.21 mg less; 95% CI, 1.06-19.37 mg less; low certainty), ketamine (mean difference, 36.81 mg less; 95% CI, 27.32-46.30 mg less; low certainty), nefopam (mean difference, 70.89 mg less; 95% CI, 64.46-77.32 mg less; low certainty), nonsteroidal anti-inflammatory drugs (mean difference, 11.07 mg less; 95% CI, 2.7-19.44 mg less; low certainty), and tramadol (mean difference, 22.14 mg less; 95% CI, 6.67-37.61 mg less; moderate certainty). Clinicians should consider using adjunct agents to limit opioid exposure and improve pain scores in critically ill patients.