Ketamine Dosing for Procedural Sedation
For procedural sedation in adults, administer ketamine 1.5-2 mg/kg IV (or 4 mg/kg IM if IV access unavailable), and in pediatric patients use 0.75-2.0 mg/kg IV (or 4 mg/kg IM), with continuous monitoring of vital signs and airway status. 1
Intravenous Dosing
Adult Patients
- Administer 1.5-2 mg/kg IV as the initial bolus dose 1, 2
- This dosing range is significantly more effective than lower doses, with only 5.5% of patients requiring additional doses compared to 54% when using 1.0 mg/kg 1, 3
- Onset of action occurs within 30-96 seconds, allowing for rapid procedural intervention 1
- Duration of effect is 10-15 minutes, with average recovery time of approximately 84 minutes 4, 1
Pediatric Patients
- Use 0.75-2.0 mg/kg IV for children aged 1 month to 20 years 4
- Age-adjusted dosing may be required: younger children need slightly higher doses (2.125 mg/kg for 2-year-olds vs 1.5 mg/kg for adults) 3
- Inadequate sedation occurs in only 3.1% of pediatric patients when combined with midazolam 4
Intramuscular Dosing
When to Use IM Route
- Administer 4 mg/kg IM when IV access is unavailable or impractical 1, 2
- Provides 100% adequacy of sedation to complete procedures 2
- Onset of action within 3-4 minutes 1, 2
- Recovery time averages approximately 90 minutes 1
Pediatric IM Dosing
- Use 4 mg/kg IM with repeat doses of 2-4 mg/kg allowed after 5-10 minutes if needed 1
- When combined with atropine 0.01 mg/kg, results in faster onset (3 minutes vs 18 minutes) and shorter discharge time compared to other sedatives 1
Combination Therapy with Midazolam
Rationale for Adding Midazolam
- Consider adding midazolam 0.05-0.2 mg/kg IV to reduce emergence reactions 4, 1
- Emergence phenomena (floating sensations, vivid dreams, hallucinations, delirium) occur in 10-30% of adults receiving ketamine alone 4, 5
- Midazolam reduces recovery agitation from 35.7% to 5.7% in patients over 10 years old 1
Combination Dosing Protocol
- Administer midazolam 0.05-0.1 mg/kg IV followed by ketamine 1.5-2 mg/kg IV 1, 6
- Alternative: midazolam 0.07 mg/kg followed by ketamine 2 mg/kg provides effective procedural sedation in adults 4, 1
- This combination provides superior sedation with fewer respiratory complications than fentanyl/midazolam regimens 1, 6
Alternative Dosing Strategies
Top-Up Technique for Intermittent Pain
- Use a smaller initial bolus (0.75-1.0 mg/kg) with a subsequent half-dose "top-up" at 8 minutes 3
- Achieves same sedation level as single large dose but with earlier recovery 3
- Better suited for procedures with intermittent painful stimuli 3
Infusion Technique for Continuous Pain
- Initial bolus: 0.25-0.35 mg/kg IV (age-adjusted) 3
- Followed by infusion: 2.5-3.5 mg/kg/hour for 15 minutes 3
- Provides more even sedation level and rapid recovery (20 minutes to drowsy state) 3
- Better suited for procedures requiring continuous analgesia 3
Cardiovascular Considerations
Hemodynamic Effects
- Ketamine produces dose-dependent increases in heart rate, blood pressure, and cardiac output through sympathetic nervous system stimulation 4
- These effects increase myocardial oxygen demand 7
Absolute Contraindications
- Avoid ketamine in patients with:
Safety Data in Older Adults
- In patients over 50 years, new onset ischemia on ECG occurred in only 9.7% (3/31 patients), with no statistically or clinically significant impact on patient disposition 7
- Consider using the lowest possible dose to obtain adequate sedation in patients with cardiovascular risk factors 7
Monitoring Requirements
Essential Monitoring Parameters
- Continuous pulse oximetry, heart rate, and blood pressure monitoring throughout sedation 1, 2, 6
- Capnography when available 1
- Vital signs documented at least every 5 minutes during deep sedation 1
- Maintain oxygen saturation >93% on room air 1
Equipment Preparation
- Airway equipment must be immediately available 2
- Bag-valve-mask apparatus ready for potential respiratory support 2
- Naloxone should be available if opioids are co-administered 4
Adverse Events and Management
Respiratory Complications
- Hypoxemia occurs in 1.6-7.3% of patients, typically transient and responsive to supplemental oxygen 1
- Bag-valve-mask ventilation required in approximately 2% of cases 1
- Brief apnea around time of injection is common 5
- Laryngospasm is rare (0.9-1.4% of cases) 2, 6
- Only 1% of pediatric patients experience transient hypoxemia when ketamine is combined with midazolam 4
Emergence Reactions
- Recovery agitation occurs in 17.6% of cases overall, with moderate-to-severe agitation in 1.6% 1, 2
- Dysphoric emergence occurs in 10-20% of cases 2, 5
- Associated with higher ASA status and decreasing age in pediatrics 1
- Midazolam effectively prevents and manages these reactions 4, 5
Gastrointestinal Effects
- Emesis without aspiration occurs in 6.7% of cases 1, 2
- Associated with increasing age in pediatric patients 1
- Nausea occurs in 4-5% of patients 6
Unique Safety Profile
- Ketamine does not depress airway or cardiovascular reflexes even when administered at doses 5-100 times greater than intended 4
- When inadvertently administered to 9 children at doses 5-100 times intended, only brief respiratory depression was observed 4
- No episodes of clinically significant respiratory depression or cardiovascular instability in large pediatric series 1
Clinical Pearls
Advantages Over Other Agents
- Ketamine possesses both analgesic and sedative properties, unlike most sedation agents 4
- Preserves pharyngeal reflexes and stimulates cardiovascular tone 5
- Superior respiratory safety profile compared to fentanyl/midazolam combinations (6% vs 24% hypoxemia, P=0.001) 6
Patient Satisfaction
- Patient satisfaction consistently high: 92-99% rate experience as "excellent" or "good" 2, 6
- Physician satisfaction similarly high: 88% rate as "excellent" or "good" 6
- All patients receiving appropriate dosing achieve adequate sedation for procedures 1, 6