What is the recommended dose of ketamine (intravenous or intramuscular anesthetic) for sedation in a 28kg child?

Ketamine Dosing for Sedation in a 28kg Child

For procedural sedation in a 28kg child, administer ketamine 1.5-2 mg/kg IV (42-56 mg) over 60 seconds, or 4 mg/kg IM (112 mg) if IV access is unavailable. 1, 2

Intravenous Administration (Preferred Route)

The standard IV dose of 1.5-2 mg/kg provides optimal sedation with minimal need for supplemental dosing. 1, 2

• For your 28kg patient: 42-56 mg IV administered slowly over 60 seconds 2
• Only 5.5% of patients require additional doses when initially dosed at 1.5 mg/kg, compared to 54% requiring additional doses at 1.0 mg/kg 1, 3
• Onset of action occurs within 30-96 seconds, allowing rapid procedural intervention 1
• Average recovery time is approximately 84 minutes (range 22-215 minutes) 1

Critical Administration Details

• Must dilute the 100 mg/mL concentration with equal volume of sterile water, normal saline, or D5W before IV administration 2
• Administer slowly over 60 seconds—rapid administration causes respiratory depression and enhanced vasopressor response 2
• Use immediately after dilution 2

Intramuscular Administration (When IV Access Unavailable)

For IM route: 4 mg/kg (112 mg for 28kg child) 1, 2

• Onset within 3-4 minutes 1, 2
• Repeat doses of 2-4 mg/kg allowed after 5-10 minutes if needed 1
• Surgical anesthesia typically lasts 12-25 minutes 2
• Bioavailability of IM ketamine is only 41%, explaining the higher dose requirement 4

Essential Monitoring Requirements

Continuous monitoring of oxygen saturation, heart rate, blood pressure, and capnography is mandatory throughout sedation. 5, 1

• Maintain oxygen saturation >93% on room air 1
• Emergency airway equipment must be immediately available 2
• Document vital signs at least every 5 minutes during deep sedation 5
• Have bag-valve-mask ventilation equipment ready—required in approximately 2% of cases 1

Adjunctive Medications to Consider

Antisialagogue (Recommended)

• Administer atropine 0.01 mg/kg (0.28 mg for 28kg child, maximum 0.5 mg) prior to ketamine induction 1, 2
• Reduces excessive salivation that can occur with ketamine 2

Benzodiazepine (For Emergence Reactions)

• Consider midazolam 0.05-0.1 mg/kg (1.4-2.8 mg for 28kg child) to reduce emergence agitation 5, 1
• Particularly beneficial in children over 10 years old, reducing recovery agitation from 35.7% to 5.7% 1
• Mild recovery agitation occurs in 17.6% of patients, moderate-to-severe in 1.6% 1

Common Adverse Effects and Management

Respiratory depression is the most critical concern, though serious events are rare. 5, 1

• Hypoxemia occurs in 1.6-7.3% of patients, typically transient and responsive to supplemental oxygen 1
• Emesis without aspiration in 6.7% of cases 1
• Laryngospasm is very rare (0.9-1.4%) 6
• Ketamine causes dose-dependent increases in heart rate and blood pressure through sympathetic stimulation 1

Contraindications

Avoid ketamine in patients with: 1

• Uncontrolled cardiovascular disease or hypertension
• Cerebrovascular disease
• Active psychosis
• Severe hepatic dysfunction
• Elevated intracranial or intraocular pressure

Clinical Pearls

• Starting with the full 1.5-2 mg/kg dose is more effective than titrating up from lower doses 1, 3
• All patients achieve adequate sedation for procedures when appropriately dosed 1, 6
• Parental satisfaction is consistently high (92-99% rate as "excellent" or "good") 6
• Ketamine provides simultaneous sedation, analgesia, and amnesia through NMDA receptor antagonism 5, 6
• Purposeless or tonic-clonic movements may occur during ketamine anesthesia—these do NOT indicate inadequate sedation or need for additional doses 2