What is the preferred choice between intramuscular (IM) midazolam and ketamine for procedural sedation?

IM Ketamine is Superior to IM Midazolam for Procedural Sedation

For intramuscular procedural sedation, ketamine at 4 mg/kg IM combined with atropine 0.01 mg/kg is the preferred choice over midazolam, providing faster onset, superior analgesia, and maintained respiratory drive. 1

Why Ketamine Outperforms Midazolam for IM Procedural Sedation

Pharmacologic Advantages of IM Ketamine

• Ketamine provides dissociative sedation with simultaneous analgesia and amnesia through NMDA receptor antagonism, whereas midazolam offers only anxiolysis and amnesia without intrinsic analgesic properties 1, 2
• IM ketamine at 4 mg/kg achieves adequate sedation within 30-96 seconds with a 98.9% procedural success rate, making it highly reliable for emergency procedures 1
• Ketamine preserves airway reflexes and respiratory drive, a critical safety advantage over midazolam which causes dose-dependent respiratory depression 3

Midazolam's Significant Limitations for IM Use

• Midazolam's major side effect is respiratory depression, with deaths reported when combined with opioids (which would be necessary to achieve analgesia comparable to ketamine) 3
• Apnea may occur up to 30 minutes after the last midazolam dose, requiring prolonged monitoring 3
• Midazolam alone provides no analgesia, necessitating additional opioid administration that increases respiratory depression risk synergistically 3

Optimal IM Ketamine Protocol

Dosing and Coadministration

• Administer ketamine 4 mg/kg IM combined with atropine 0.01 mg/kg (minimum 0.1 mg, maximum 0.5 mg) to prevent hypersalivation and reduce post-procedural vomiting 1
• The 4 mg/kg IM dose is specifically recommended by the American College of Emergency Physicians for procedural sedation, providing faster onset and shorter discharge times compared to alternatives 1

Expected Adverse Effects (Manageable)

• Emesis occurs in 7-8% of patients 1
• Recovery agitation occurs in 7.1% of pediatric patients, higher in younger children 1
• Laryngospasm occurs in only 0.9-1.4% of patients without requiring intubation 1

Monitoring Requirements

• Continuous vital sign monitoring is mandatory, including pulse oximetry, heart rate, and blood pressure throughout the procedure 1
• Average recovery time is 84 minutes (range 22-215 minutes) 1

When to Consider Adjunctive Midazolam

• Midazolam 0.05 mg/kg IV may be added to ketamine to reduce emergence reactions, particularly in adults and older children 1, 4
• This combination (ketamine + midazolam) demonstrates superior efficacy: in adult ED patients receiving 0.07 mg/kg midazolam followed by 2 mg/kg ketamine IV, only 1% were dissatisfied with sedation, with minimal serious adverse events 5

Critical Pitfalls to Avoid

• Never underdose ketamine—this is the most common error, resulting in inadequate sedation requiring supplemental doses in over 50% of patients 1
• Do not use midazolam alone for painful procedures, as it lacks analgesic properties and will require opioid coadministration, dramatically increasing respiratory depression risk 3
• Avoid rapid midazolam administration, as this administration-related phenomenon increases apneic episodes 3

Special Populations

Pediatric Considerations

• Ketamine is designated as a Level A recommendation by the American College of Emergency Physicians for safe administration to children for procedural sedation 3
• Ketamine/midazolam combinations show significantly lower distress scores during orthopedic procedures compared to fentanyl/midazolam (1.12 vs 2.70, P<0.0001) 2
• Parental satisfaction with ketamine sedation is consistently 92-99% rating the experience as "excellent" or "good" 2

Adult Considerations

• The combination of midazolam and ketamine receives a Level B recommendation for effectiveness in adult ED procedural sedation 3
• Adults may benefit more from adjunctive midazolam to reduce emergence phenomena 4