Ketamine

Question 1

Ketamine Chemical Name and Class

Answer 1

Chemical name: 2-(o-chlorophenyl)-2(methylamino) cyclohexanone hydrochloride

Class: phencyclidine derivative

Question 2

Ketamine Clinical Uses

Answer 2

GA induction and maintenance
Monitored anesthesia care (MAC)
Anesthetic
Analgesic
Antidepressant

Question 3

Ketamine MOA (6)

Answer 3

Non-competitive antagonist at NMDA receptor ion channels.

Ketamine blocks the open channel, inhibiting the excitatory response to glutamate.

Provides amnesic and potent analgesia.

Produces a “dissociative state” by depressing the cerebral cortex and thalamus and stimulating the hippocampus.

It also binds with opioid, MAO, serotonin, NE, muscarinic and sodium channels

Ketamine inhibits neuronal sodium channels (producing a modest local anesthetic action) and calcium channels (causing cerebral vasodilation)

Question 4

Ketamine IV and IM Induction Doses

Answer 4

IV Induction 1-2 mg/kg

IM Induction 4-6 mg/kg

Question 5

Ketamine Sedation and Multi-modal Pain Infusion Doses

Answer 5

Sedation 1-3 mcg/kg/min or 0.5-1 mg/kg boluses as needed

Multi-modal infusion – 3-5 mcg/kg/minute

Question 6

Ketamine IV Onset and DOA

Answer 6

Onset: 2-5 minute
DOA: 10-20 minutes (may require an hour for full orientation)

Question 7

IM Ketamine Onset

Answer 7

Onset: 20 minutes

Question 8

Ketamine Distribution (protein binding)

Answer 8

Least protein bound of induction agents

Question 9

Ketamine Metabolism

Answer 9

P450 enzymes in the liver

Chronic ketamine use induces enzymes that metabolize it

Active metabolite: norketamine is 1/3 as potent as ketamine and is renally excreted

Question 10

Ketamine Excretion

Answer 10

Excreted by the kidneys

Question 11

Ketamine CNS Effects (5)

Answer 11

Increased CMRO2, CBF, ICP

Dissociative

Analgesic

Depression

Associated with emergence delirium, nightmares and hallucinations

Question 12

Ketamine CNS Delirium Risk Factors and Prevention

Answer 12

Benzodiazepines are an effective means of prevention

Risk factors: age > 15, female gender, personality disorder, dose > 2mg/kg

Question 13

Ketamine CV Effects (3)

Answer 13

SNS stimulant

Increased SVR, HR, myocardial O2 consumption, PVR

Mild myocardial depression

Question 14

Ketamine Respiratory Effects (4)

Answer 14

Bronchodilator

Maintains respiratory rate

Preserves reflexes at low dose

Increased secretions, often paired with an antisialogue like glycopyrrolate

Question 15

Ketamine Ocular Effects (2)

Answer 15

Nystagmus

Increased IOP

Question 16

Ketamine Precautionary Considerations (8)

Answer 16

Hypertension

Angina

CHF

Increased intracranial pressure

Increased ocular pressure

Auditory/Visual hallucinations

Airway problems d/t increase secretions

Emergence reactions – vivid dreams, hallucinations (lasts 1-3 hours) and can be reduced with propofol and/or benzodiazepines