Ketamine

Question 1

What is the MOA of ketamine?

Answer 1

• Dissociative anesthesia (not hypnotic)→ intense analgesia and profound amnesia
• Depresses neuronal function of cortex and thalamus
• Stimulates limbic system

Question 2

What factors contribute to the analgesic effect of ketamine?

Answer 2

• Activates opioid receptors (mu, delta, kappa, weak sigma)
• Activates subcortical neurons in spinal tract (monoaminergic, muscarinic, VG Na+, L-type Ca2+ channels, nAchRs)

Question 3

What are benefits of using ketamine?

Answer 3

• Dissociative anesthesia
• Pain relief
• Decrease other anesthesia drugs
• Chronic pain
• Decrease narcotic use

Question 4

Preparation of ketamine:

Answer 4

• 1%, 5%, or 10% solutions
• 5% (50mg/mL) most common

Question 5

What are some reasons why ketamine is better than etomidate and propofol?

Answer 5

• No pain at injection
• Profound analgesia at subanesthetic doses

Question 6

Adult induction dose of Ketamine:

Answer 6

• 0.5-1.5mg/kg IV
• 4-8mg/kg IM
• 10mg/kg PO

Question 7

What is the IV/IM maintenance doses of ketamine to provide intense analgesia?

Answer 7

• IV: 0.2-0.5mg/kg
• IM: 4-8mg/kg

Question 8

What is the onset and duration of IV Ketamine?

Answer 8

• Onset: 1 min
• Duration: 10-20min
  EPS symptoms will last up to 1hour

Question 9

What meds are in a ketamine dart?

Answer 9

Ketamine, Versed, Robinol

Question 10

What is the onset/duration of IM ketamine?

Answer 10

• Onset: 5 min
• Duration: a little longer than IV (iv is 10-20min)

Question 11

What are drug interaction with ketamine?

Answer 11

• Volatiles: hypotension
• Non depolarizing NMBDs: Enhanced
• Succinylcholine: Prolonged
• MAOIs: Increases EPI

Question 12

What is the E1/2time of ketamine?

Answer 12

2 hours: affects wake up from drug

Question 13

How is ketamine broken down in the body?

Answer 13

• High hepatic clearance (low protein binding)
• 20-30% metabolism to active nor-ketamine
• Induced CYP450→Responsive in 30min
• Excreted by kidneys

Question 14

How does nor-ketamine compare to ketamine?

Answer 14

1/3-1/5 potency of ketamine→ still causes prolonged anesthesia

Question 15

Clinical uses for ketamine:

Answer 15

• Acutely hypovolemic pts (stimulates SNS)
• Asthmatic and MH pts (bronchodilator)

Question 16

What are CV effects of ketamine?

Answer 16

Increases SVR, PVR, HR, MVO2, SNS outflow, Epi/NE (inhibit reuptake)

Question 17

Why might airway not be fully protected if patient received ketamine?

Answer 17

D/t dissociation

Question 18

How does ketamine benefit a pt with status asthmaticus?

Answer 18

Intense bronchodilation

Question 19

What should be given prior to ketamine to mitigate?

Answer 19

Robinol→ decrease salivary secretions associated with ketamine

Question 20

What is the MOA of ketamine causing hallucinations/emergence delirium? How can this be minimized?

Answer 20

• Depression of inferior colliculus and medial geniculate nucleus
• IV benzo 5 minutes prior OR alpha 2 agonists

Question 21

What are potential side effects of ketamine aside from emergence delirium and CV effects?

Answer 21

• Inhibit platelet aggregation
• Inhibit cytosolic free calcium concentration
• Prolong apnea from succs (inhibits plasma cholinesterases)

Question 22

How are CV effects from ketamine blunted?

Answer 22

Premed with benzo or inhalation anesthetic/N2O

Question 23

What are CNS effects of ketamine?

Answer 23

• Potent cerebral vasodilator (modest decrease in ICP)
• Increases CBF by 60%