Ketamine Flashcards
Ketamine
Pharmacology
- Ketamine antagonises N-methyl-D-aspartate (NMDA) receptors; also interacts with muscarinic receptors, descending
monoaminergic pain pathways, voltage-sensitive calcium channels and opioid receptors in brain and spinal cord.
Ketamine
Metabolism
- Ketamine undergoes extensive hepatic metabolism. About 90% of ketamine is excreted in the urine, mostly as
metabolites, with only about 2 to 4% as the unchanged drug. Approximately 5% is recovered in the faeces.
Route Onset Duration Half-Life
Ketamine
Route Onset Duration Half-Life
IV / IO
Ketamine
Route Onset Duration Half-Life
IV / IO 30sec 5-20min 45min
Ketamine
Indications
- Analgesia.
- Agitation in the trauma & critically unwell patient.
- Behavioural disturbance.
- Cardiac arrest.
Ketamine
Contraindications
⛔ Allergy or hypersensitivity to ketamine.
⛔ Patients < 6 years of age.
⛔ Suspected ACS or acute heart failure.
Ketamine
Adverse/Side Effects
Common
Infrequent
Rare
- Common (>1%) – raised BP and pulse rate, increased muscle tone (sometimes tonic-clonic and resembling seizures), lacrimation, hypersalivation, nausea and vomiting, raised intracranial pressure, raised intraocular pressure, emergence reactions.
- Infrequent (0.1 – <1%) – diplopia, nystagmus, hypotension and bradycardia, pain on injection, erythema, morbilliform rash.
- Rare (<0.1%) – apnoea, laryngospasm, arrhythmias, anaphylaxis.
Ketamine
Precautions / Warnings
9
- During the administration of ketamine, respiratory depression, apnoea, respiratory arrest, and/or cardiac arrest can occur
and regular close monitoring of the patient and vital signs should occur (especially respiratory effort/ETCO2 and cardiac
monitoring). - A transient rise in blood pressure of 20–25% can occur a few minutes after IV injection.
- Some patients may have involuntary movements of the arms and legs during IV administration.
- Emergent reactions may occur during recovery and sometimes up to 24 hours later. These include vivid dreams, hallucinations, delirium, and irrational behaviour. Reactions are less common with lower doses used for analgesia.
- Conditions that may be worsened by an increase in BP and/or heart rate (eg severe hypertension, stroke, intracerebral
haemorrhage, angina, AMI, stenotic valvular heart disease, tachyarrhythmias, chronic heart failure)—ketomine increases
BP and heart rate; use cautiously. - Psychiatric disorders—hallucinations, irrational behaviour, and other effects may occur; minimise stimulation during recovery to reduce the risk of emergence reactions.
- Pregnancy: Category B3 - The safe use of ketamine in pregnancy has not been established, and such use is not recommended.
- Use in lactation – Ketamine is likely to be excreted in breast milk and therefore breastfeeding should be discontinued
when ketamine is in use. - Effects on Ability to Drive and Use Machines – This medicine can temporarily impair cognitive function, which can affect a patient’s ability to drive safely. Patients should be cautioned that driving an automobile, operating machinery or
engaging in other hazardous activities should not be undertaken for 24 hours or after administration (unlikely required in
NSWA setting).
Ketamine
Interactions 2
- The use of ketamine with other central nervous system (CNS) depressants (e.g. ethanol) can potentiate CNS depression
and/or increase risk of developing respiratory depression. - Benzodiazepines may prolong the half-life of ketamine.
Ketamine
Notes 2
- Clinicians must ensure they follow all procedures associated with procedural sedation when administering ketamine,
including applying EtCO2 where practical. - Emergence reactions associated with ketamine administration for analgesia in adult patients may be managed with
midazolam. Be aware this may induce further loss of consciousness.
Ketamine
CIPRIC
ADULT ONLY Dose
IV - Diluted Initial Dose: 20mg diluted bolus
Repeat: 3 minutes
Maximum Total Dose: 100mg
Ketamine
Analgesia
Note
- In the elderly, frail and/or critically ill (e.g. shocked) patient use 50% of the recommended lower end of the adult dose
range.
Ketamine
Analgesia
Adult Dose
IV/IO Diluted
Initial Dose: 10-20mg diluted
Repeat: 5 minutes
Maximum Total Dose: 200mg
IM
Initial Dose: 1mg/kg
Repeat: 15 minutes
Maximum Total Dose: 2mg/kg (up to 200mg)
Ketamine
Analgesia
Paed Dose
≥ 6 years of age
IV/IO Diluted
Initial Dose: 0.1mg/kg diluted
Repeat: 5 minutes
Maximum Total Dose: 200mg
IM
Initial Dose: 1mg/kg
Repeat: No repeat
Maximum Total Dose: 1mg/kg
Ketamine
Agitation in the Trauma & Critically Unwell Pt
Dosage Notes
First line sedation
Ketamine
Agitation in the Trauma & Critically Unwell Pt
Adult Dose
IV/IO Diluted
Initial Dose: 10-20mg
Repeat: 3-5 minutes
Maximum Total Dose: 200mg
IM Undiluted
Initial Dose: 0.5mg/kg
Repeat: 10 minutes
Maximum Total Dose: 2mg/kg (up to 200mg)
Ketamine
Agitation in the Trauma & Critically Unwell Pt
Paed Dose ≥ 6 years of age
IV/IO Diluted
Initial Dose: 0.1mg/kg
Repeat: 3-5 minutes
Maximum Total Dose: 100mg
IM Undiluted
Initial Dose: 0.5mg/kg
Repeat: 10 minutes
Maximum Total Dose: 1mg/kg (up to 100mg)
Ketamine
Behavioural Disturbance
Indications
Note All ages ≥ 6 years of age for Behavioural Disturbance
- 1st line for acutely violent (dangerous) patients who present an immediate risk to themselves, bystanders, or clinicians.
- Third line if droperidol is ineffective.
Ketamine
Behavioural Disturbance
1st Line
- patients ≥ 6 years of age
IM - Undiluted
Initial Dose: 4mg/kg Undiluted
Repeat: Nil
Maximum Total Dose: 4mg/kg
Ketamine
Behavioural Disturbance
3rd Line if Droperidol ineffective
- patients ≥ 6 years of age
IM - Undiluted
Initial Dose: 2mg/kg Undiluted
Repeat: Nil
Maximum Total Dose: 2mg/kg
IV - Diluted
Initial Dose: 0.25mg/kg Diluted (Max bolus 30mg)
Repeat: 3-5 minutes
Maximum Total Dose: 200mg
