What is the recommended intramuscular (IM) dose of Ketamine for procedural sedation in adults?

Intramuscular Ketamine Dosing for Procedural Sedation in Adults

For procedural sedation in adults, administer ketamine 4 mg/kg intramuscularly, which produces surgical anesthesia within 3-4 minutes with effects lasting 12-25 minutes. 1

FDA-Approved Dosing Guidelines

The FDA label provides clear dosing parameters for IM ketamine administration 1:

• Initial dose range: 6.5 to 13 mg/kg IM
• Standard effective dose: 9 to 13 mg/kg IM produces surgical anesthesia within 3-4 minutes 1
• Duration of effect: Anesthetic effect typically lasts 12-25 minutes 1
• Repeat dosing: Additional increments of one-half to the full induction dose can be administered as needed for maintenance 1

Emergency Department Practice Recommendations

For ED procedural sedation, the practical dosing differs from full anesthesia 2:

• Standard IM dose: 4 mg/kg for procedural sedation 3, 2
• Repeat dosing if needed: 2-4 mg/kg after 5-10 minutes if initial sedation inadequate 2
• Onset of action: Approximately 3 minutes with IM administration 2
• Time to discharge: Median 110 minutes from administration 4

Comparison with IV Administration

When comparing routes, both are effective but have different characteristics 5:

• IV dosing: 1.5-2 mg/kg produces adequate sedation 3, 2, 6
• Onset: IV route has faster onset (30-96 seconds) versus IM (3 minutes) 2, 4
• Adverse events: Similar frequency of recovery agitation (13% IV vs 17% IM), respiratory events (0% both routes), and nausea/vomiting (28% IV vs 34% IM) 5

Adjunctive Midazolam Considerations

Consider co-administering midazolam 0.03 mg/kg to reduce emergence reactions, which decreases recovery agitation from 25% to 8% (NNT=6). 5

The evidence for midazolam co-administration 3, 5:

• Reduces recovery agitation significantly (difference 17%, 95% CI 6-28%) 5
• Does not increase respiratory depression risk 3
• Particularly beneficial in patients >10 years old 3

Critical Safety Requirements

All ketamine administration requires specific monitoring and preparation 1:

• Provider qualifications: Must be administered by or under direction of physicians experienced in general anesthesia and airway management 1
• Continuous monitoring: Vital signs including oxygen saturation, heart rate, and blood pressure 2, 1
• Emergency equipment: Airway equipment must be immediately available 1
• Antisialagogue: Administer prior to induction due to potential for salivation 1

Contraindications and Precautions

Avoid ketamine in specific patient populations 2, 1:

• Patients where blood pressure elevation would constitute serious hazard 1
• Ischemic heart disease, cerebrovascular disease, or uncontrolled hypertension 2
• Active psychosis, severe hepatic dysfunction 2
• Elevated intracranial or intraocular pressure 2

Expected Adverse Events

Common side effects to anticipate 2, 4, 7:

• Recovery agitation: 17.6% mild, 1.6% moderate-to-severe 4
• Emesis: 6.7% (without aspiration) 4
• Dysphoric emergence: 10-20% of cases 7
• Cardiovascular: Transient increases in blood pressure and heart rate are expected 1, 8
• Laryngospasm: Very rare (0.9-1.4%) 3

Clinical Pearls

The 4 mg/kg IM dose represents the optimal balance between efficacy and safety for ED procedural sedation, providing 100% adequacy of sedation to complete procedures while maintaining a favorable safety profile. 3

Key practice points 3, 2:

• Higher total doses result in longer recovery times 1
• Purposeless tonic-clonic movements may occur and do not indicate need for additional dosing 1
• Average recovery time is approximately 84 minutes (range 22-215 minutes) 4
• Patient satisfaction is consistently high (92-99% rate as "excellent" or "good") 6