Doses

Induction

The dose of ketamine for induction:

Intravenous. Ketamine 1-2 mg/kg IV. Onset of anaesthesia is after 90 seconds (may cause temporary apnoea if given quickly); e.g. for a 20kg child, give 20 mg-40 mg IV
Intramuscular. Ketamine 5-8 mg/kg IM. Onset is slow (5 minutes), and recovery may be slow; e.g. for a 20 kg child, give 100 mg IM. atropine IM 20mcg/kg can be given with IM ketamine

Maintenance

The dose of ketamine for maintenance:

IV bolus. Titrate boluses of ketamine 0.5 mg/kg according to response, usually required every 15 minutes; e.g. for a 20 kg child give additional boluses of 10 mg when required
IV infusion anaesthesia (older children only); titrate an infusion of 2-4 mg/kg/hour to response. Be cautious using infusions in children under 20kg.

Beware accidental overdose - use a 100 ml non-microdrop burette (1 ml = 15 drops) or an infusion pump:

Make up a solution of ketamine 1 mg/ml in 100 ml or 50 ml saline
Run at 0.5-1 drops/kg/minute (burette) or 2-4 ml/kg/hour (infusion pump); e.g. 30 kg child use 15-30 drops/minute (burette) or 60-120 ml/hour (infusion pump)

Analgesia

The dose of ketamine for analgesia:

Bolus for analgesia during surgery: ketamine 0.5 mg/kg e.g. 20 kg child, give a bolus of 10 mg
IV infusion analgesia may be used for older children if the child can be closely monitored e.g. in HDU/ICU

Beware accidental overdose - an infusion pump must be used and the child should be monitored carefully:

Make up a solution of ketamine 50 mg in 50 ml saline (1 mg/ml)
Run at 0.02-0.04 ml/kg/hr (0.02-0.04 mg/kg/hr) e.g. 30 kg child, give an infusion of 0.6-1.2 ml/hr (0.6-1.2 mg/hr)

Sedation

The dose of ketamine for sedation:

Premedication: Give ketamine 5 mg/kg PO 20 minutes preop. Ketamine has a bitter taste; mix with sugar in a small amount of water
Suture of lacerations: Low-dose ketamine 2-4 mg/kg IM may be used to provide sedation for short procedures. Monitor using oxygen saturation
Burns dressing: Give ketamine 7.5 mg/kg PO with midazolam 0.25 mg/kg PO 15 mins prior to dressing change. Make sure everything is prepared and monitor the child carefully. GA may be preferable