The American Society of Regional Anesthesia and Pain Medicine, American Academy of Pain Medicine, and American Society of Anesthesiologists consensus guidelines describe ketamine as a dissociative anesthetic with dose-dependent clinical use spanning analgesic, subanesthetic, and procedural sedation/anesthetic ranges: the FDA-listed anesthetic induction dose is 1–4.5 mg/kg IV, with an average dose of 2 mg/kg, and common subanesthetic analgesic dosing in clinical practice is an IV bolus of 0.3–0.5 mg/kg, with or without an infusion usually initiated at 0.1–0.2 mg/kg/hour; for acute pain settings without intensive monitoring, the consensus recommendation is that bolus doses generally not exceed 0.35 mg/kg and infusions generally not exceed 1 mg/kg/hour, while noting that lower infusion doses of 0.1–0.5 mg/kg/hour may be needed to balance analgesia and adverse effects. The Royal Children’s Hospital Melbourne clinical practice guideline characterizes the ketamine dissociative state as a trance-like state with catalepsy, effective analgesia, usually total amnesia, maintained airway reflexes, slight increases in blood pressure and heart rate, and typical nystagmus and lacrimation, and recommends procedural sedation dosing of 1–1.5 mg/kg IV over 1–2 minutes with 0.25–0.5 mg/kg incremental IV doses every 10 minutes as needed, up to a maximum of 4.5 mg/kg, while stating that IV doses greater than 2.5 mg/kg are associated with increased adverse-event risk; it also lists IM procedural sedation dosing as 4 mg/kg initially, up to a maximum of 6 mg/kg, with a repeat 2 mg/kg dose after 10 minutes if sedation is inadequate. Neither source provides a ketamine infusion dose range specifically for non-intubated patients with status epilepticus, and the Royal Children’s Hospital Melbourne guideline explicitly states that uses other than procedural sedation are beyond its scope; therefore, based only on these attached sources, the only directly stated non-intensively monitored infusion recommendation is the American Society of Regional Anesthesia and Pain Medicine, American Academy of Pain Medicine, and American Society of Anesthesiologists consensus guideline range of generally not exceeding 1 mg/kg/hour, with 0.1–0.5 mg/kg/hour described as a lower-dose range used to balance analgesia and adverse effects, but this is not a status epilepticus recommendation. [1], [2]
A 2018 systematic review described ketamine as having a pharmacological profile characterized by a “dissociative anesthetic state,” defined as anesthesia with catalepsy, catatonia, analgesia, and amnesia that does not necessarily cause loss of consciousness; however, the review did not identify a specific ketamine dose threshold at which dissociative or anesthetic effects occur. Across published refractory status epilepticus studies, ketamine dosing was highly heterogeneous and did not appear to be an independent prognostic factor. In the adult case series, reported ketamine doses ranged from 0.07 to 15 mg/kg/h, while in paediatric case series and reported doses ranged from 0.04 to 10 mg/kg/h. The review did not provide a recommended dose range for non-intubated ketamine infusion in status epilepticus patients. It reported that endotracheal intubation was avoided or unnecessary in selected cases, including two adult patients in whom ketamine was effective, five children with non-convulsive status epilepticus treated with oral ketamine, and five of 13 children with refractory convulsive status epilepticus in the Ilvento et al. series, where the mean ketamine infusion dose was 1.8 mg/kg/h with a reported range of 0.42–3.6 mg/kg/h. [3]
A 2018 systematic review and case report series evaluated ketamine use in refractory status epilepticus (RSE) and found that, although ketamine is described as standard in anesthetic induction, the paper does not specify the dose at which ketamine produces dissociative or anesthetic effects and does not provide a recommended dose range for non-intubated ketamine infusion in status epilepticus patients. Across the reviewed RSE literature, ketamine dosing varied substantially: adult studies reported bolus doses of 0.5–5 mg/kg and maintenance infusion doses of 0.05–10.5 mg/kg/hour, while pediatric studies reported bolus doses of 0.002–5 mg/kg and continuous infusion doses of 0.0075–10.5 mg/kg/hour. The authors emphasized that no definitive ketamine protocol exists for RSE, that there is scarce safety information for long-term infusion, and that prolonged high-dose ketamine, particularly with midazolam, was associated in their review and cases with metabolic acidosis and hemodynamic instability. Therefore, available evidence supports reporting observed RSE dosing ranges rather than defining a dissociative/anesthetic threshold or recommending a non-intubated infusion range. [4]