Intramuscular Ketamine Dosing
For procedural sedation and anesthesia induction, administer 4 mg/kg IM in both adults and children, with onset of action in 3-4 minutes; for sub-dissociative analgesia, no established IM dosing exists in the current evidence base. 1
Procedural Sedation/Anesthesia Induction
Pediatric Patients (≤17 years)
- Administer 4 mg/kg IM as the standard dose for procedural sedation, as recommended by the American Academy of Pediatrics 1
- Repeat doses of 2-4 mg/kg may be given after 5-10 minutes if initial sedation is inadequate 1
- Onset of action occurs within 3-4 minutes when combined with atropine 0.01 mg/kg IM, significantly faster than alternative sedatives 1
- Duration of optimal sedation averages 37.2 minutes with IM administration 2
- Recovery time to discharge readiness is approximately 72-90 minutes 1, 2
Clinical advantage: IM ketamine requires fewer rescue doses (10% of patients) compared to IV administration (26.7% of patients), making it more reliable for maintaining adequate sedation throughout the procedure 2
Adult Patients (≥18 years)
- Use the same 4 mg/kg IM dose as in pediatric patients when IV access is unavailable or impractical 1
- Onset of action is 3-4 minutes 1
- Average recovery time is approximately 90 minutes 1
Adjunctive Medication
- Administer atropine 0.01 mg/kg IM (minimum 0.1 mg, maximum 0.5 mg) before ketamine to reduce excessive salivation and facilitate airway management 1
- This combination results in faster onset (3 minutes vs. 18 minutes) and shorter time to discharge compared to ketamine alone 1
Sub-Dissociative Analgesia
No established IM dosing regimen exists for sub-dissociative analgesia in the provided evidence. The literature focuses exclusively on IV administration for this indication, with typical doses of 0.1-0.5 mg/kg IV 3. The IM route is not validated or recommended for sub-dissociative analgesia based on current guidelines.
Monitoring Requirements
- Maintain continuous pulse oximetry with target SpO2 >93% on room air throughout the procedure 1, 4
- Monitor heart rate and blood pressure at regular intervals 1
- Document vital signs at least every 5 minutes during deep sedation 1
- Consider capnography when available 1
Contraindications
Avoid IM ketamine in patients with:
- Ischemic heart disease, cerebrovascular disease, or uncontrolled hypertension 1
- Active psychosis 1
- Severe hepatic dysfunction 1
- Elevated intracranial or intraocular pressure 1
Common Adverse Effects
- Emesis occurs in 6.7% of cases, with higher incidence in older children 1
- Mild recovery agitation occurs in approximately 17.6% of patients 1
- Moderate-to-severe agitation occurs in only 1.6% of patients 1
- Overall side effects occur in 40% of IM patients versus 60% of IV patients 2
Key Clinical Pearls
IM administration provides more tranquil recovery (90% comfortable recovery) compared to IV administration (73.3% comfortable recovery), making it preferable when IV access is difficult 2
The bioavailability of IM ketamine is only 41%, which explains why the IM dose (4 mg/kg) must be substantially higher than the IV dose (1.5-2 mg/kg) to achieve equivalent plasma concentrations 5