Anaes · Anaesthetic adjuncts
Anaesthetic adjuncts
Also known as Anaesthetic adjuncts · Dexmedetomidine · Ketamine · Lidocaine infusion · Magnesium · Clonidine · Gabapentinoid · Benzodiazepine
Anaesthetic adjuncts spare opioid/volatile, improve analgesia or stabilise emergence: alpha-2 agonists with cooperative sedation and minimal respiratory depression (Weerink 2017), ketamine/esketamine with fatigue reduction at POD3/7 but not POD1 (Al Subhi 2026, 8 RCTs n equals 906), IV lidocaine in open abdominal surgery with opioid reduction (Muntean 2026, 10 RCTs n equals 658), magnesium in supratentorial craniotomy with MAP minus 4.65 and fentanyl SMD minus 1.01 (Tarimah 2026, 9 RCTs), and intrathecal adjuvants with 183-RCT hierarchy (Ollosu 2026, n equals 14431). Each needs a dose, duration, stop rule and toxicity plan. Doses are taught-formulary.
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Red flags
- Dexmedetomidine and clonidine cause bradycardia and hypotension — reduce or stop the infusion before stacking vasopressors blindly.
- Intravenous lidocaine infusions carry LAST risk — account for total amide dose from all regional and systemic sources.
- Magnesium potentiates neuromuscular blockade — confirm TOF recovery before extubation.
- Neuraxial morphine causes delayed respiratory depression (peak 6–24 h) — overnight monitoring is mandatory.
- Gabapentinoids sedate and can depress respiration with opioids, especially in the elderly and renally impaired.
Meet the patient
A 45-year-old man on long-term oxycodone for chronic back pain presents for open bowel resection. Opioid alone will not suffice. IV lidocaine in open abdominal surgery generally reduces opioid consumption (Muntean 2026, 10 RCTs n equals 658, e.g. minus 55.9 mg/72 h and minus 13.9 mg/24 h signals); ketamine fatigue benefit is POD3/7 not POD1 (Al Subhi 2026). Plan multimodal with total amide accounting.[2][1]
Examiners test doses, mechanisms, contraindications and toxicity interactions. Trial-exact anchors: Mg MAP minus 4.65, fentanyl SMD minus 1.01, S100B SMD minus 0.81 (Tarimah 2026); intrathecal hierarchy with dexmedetomidine pain-12 h benefit but prolonged motor block plus bradycardia (Ollosu 2026, 183 RCTs). Doses taught-formulary.[3][4]
References5ShowHide
- [1]Al Subhi M, et al. Effect of Perioperative Ketamine and Esketamine on Postoperative Fatigue: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Medicina (Kaunas), 2026.PMID 42356168
- [2]Muntean C, et al. Intravenous Lidocaine as an Adjunct for Postoperative Recovery After Open Abdominal Surgery: A Systematic Review J Clin Med, 2026.PMID 42278931
- [3]Tarimah K, et al. Magnesium Sulfate as a Multimodal Anesthetic Adjuvant in Brain Tumor Surgery: A Systematic Review and Meta-Analysis of Hemodynamic, Analgesic, and Biomarker Outcomes J Clin Med, 2026.PMID 42355804
- [4]Ollosu M, et al. Efficacy and safety of intrathecal adjuvants in lower limb orthopaedic surgery: a systematic review and network meta-analysis of randomised controlled trials J Anesth Analg Crit Care, 2026.PMID 42321879
- [5]Weerink MAS, et al. Clinical Pharmacokinetics and Pharmacodynamics of Dexmedetomidine. Clin Pharmacokinet, 2017.PMID 28105598