What is the appropriate dosage and administration of ketamine and atropine for procedural sedation?

Ketamine and Atropine for Procedural Sedation

For procedural sedation in children, administer ketamine at 1.5-2 mg/kg IV (or 4 mg/kg IM) combined with atropine 0.01 mg/kg, based on American College of Emergency Physicians guidelines demonstrating superior efficacy and safety. 1, 2

Intravenous Dosing Protocol

Ketamine 1.5-2 mg/kg IV is the optimal dose, with only 5.5% of patients requiring additional doses compared to 54% with lower 1 mg/kg dosing. 1 The FDA-approved range is 1-4.5 mg/kg IV, but 2 mg/kg produces 5-10 minutes of surgical anesthesia within 30 seconds. 2

• Administer slowly over 60 seconds to prevent respiratory depression and enhanced vasopressor response 2
• Onset of adequate sedation occurs within 30-96 seconds 1, 3
• Success rate for procedural completion is 98.9% with appropriate dosing 3
• Average recovery time is 84 minutes (range 22-215 minutes) 1, 2

Intramuscular Dosing Protocol

Ketamine 4 mg/kg IM combined with atropine 0.01 mg/kg provides faster onset (3 minutes vs 18 minutes) and shorter discharge time (85 minutes vs 113 minutes) compared to other sedatives. 1

• FDA-approved IM range is 6.5-13 mg/kg, with 9-13 mg/kg producing surgical anesthesia within 3-4 minutes 2
• The 4 mg/kg dose is preferred for procedural sedation based on emergency medicine guidelines 4, 5
• Anesthetic effect typically lasts 12-25 minutes 2

Atropine Coadministration

Atropine 0.01 mg/kg (minimum 0.1 mg, maximum 0.5 mg) should be administered with ketamine to prevent hypersalivation and potentially reduce post-procedural vomiting. 4, 2

Evidence Supporting Atropine Use:

• Reduces hypersalivation from 30.8% to 11.4% (OR 0.29,95% CI 0.09-0.91) 6
• May decrease post-procedural vomiting from 25.6% to 9.1% (OR 0.29,95% CI 0.09-1.02) 6
• FDA labeling recommends antisialagogue administration prior to ketamine induction 2

Counterpoint on Atropine:

One study found atropine reduced hypersalivation statistically but provided no clinical benefit, as only 9.7% of placebo patients had significant secretions requiring simple interventions like suctioning. 7 However, the preponderance of guideline evidence and FDA labeling supports routine atropine use. 4, 2

Atropine-Associated Side Effects:

• Transient rash occurs in 22.7% with atropine vs 5.1% without (OR 5.44,95% CI 1.11-26.6) 6
• Increased heart rate is expected and clinically insignificant 7

Preparation and Administration

For IV ketamine 100 mg/mL concentration: Must dilute with equal volume of Sterile Water, Normal Saline, or 5% Dextrose before IV administration. Use immediately after dilution. 2

For maintenance infusion: Dilute to 1 mg/mL concentration (10 mL of 50 mg/mL vial in 500 mL carrier solution) and administer at 0.1-0.5 mg/minute. 2

Monitoring Requirements

Continuous vital sign monitoring is mandatory during ketamine administration, including: 1, 2

• Pulse oximetry (maintain SpO2 >93% on room air) 3
• Heart rate and blood pressure at regular intervals 1
• Respiratory status throughout procedure and recovery 3
• Emergency airway equipment must be immediately available 2

Expected Adverse Effects

• Emesis: 7-8% of patients 1, 3
• Nausea: 4-5% of patients 1
• Recovery agitation: 7.1% in pediatric patients, higher in younger children 8
• Laryngospasm: 0.9-1.4% of patients 3
• Airway complications: 1.4% without requiring intubation or causing sequelae 4

Adjunctive Midazolam Consideration

Midazolam 0.05 mg/kg IV may be added to reduce emergence reactions, particularly in adults where recovery agitation occurs in 13% of cases. 3, 8 However, in children, midazolam does not significantly reduce recovery agitation and may increase it in patients >10 years old. 4

Critical Pitfalls to Avoid

Underdosing ketamine is the most common error: Using 1 mg/kg IV results in inadequate sedation requiring supplemental doses in over 50% of patients, prolonging procedure time and increasing total drug exposure. 1, 3

Rapid IV bolus administration causes respiratory depression and enhanced vasopressor response—always administer over 60 seconds. 2

Failure to follow NPO guidelines increases aspiration risk, though ketamine preserves some airway reflexes. 2