Induction Meds: Ketamine Flashcards
(45 cards)
What type of drug is ketamine?
- Phenycyclidine derivative;
NMDA receptor antagonist (PCP; “angel dust”)
What signs and symptoms does dissociative anesthesia (ketamine) produce?
“Zonked” state
- Non-communicative but awake
- Hyptonus & purposeful movements
- Cataleptic state: eyes open with a slow nystagmic gaze (“no one’s home”)
What are Ketamine’s two greatest advantages over Propofol or Etomidate?
- No pain at injection (no propylene glycol)
- Profound analgesia at sub-anesthetic doses.
What are the two greatest disadvantages of ketamine?
- Emergence delirium
- Abuse potential
What is Benzethonium Chloride?
Ketamine preservative that inhibits ACh receptors
Differentiate S(+)Ketamine vs R(-)Ketamine.
S-Ketamine (left-handed isomer) is essentially better.
- More intense analgesia
- ↑ metabolism & recovery
- Less salivation
- Lower emergence delirium
What benefits does a racemic ketamine mixture offer?
- Less fatigue & cognitive impairment
- Inhibits catecholamine reuptake at nerve endings (like cocaine).
What is Ketamine’s main mechanism of action?
- Non-competitive inhibition of NMDA (N-methyl-D-aspartate) receptors by inhibiting pre-synaptic release of glutamate.
Glutamate is most abundant excitatory NT in CNS
What are Ketamine’s secondary receptor sites?
- Weak GABA-A effects.
- Opioid (μ, δ, and κ)
What is Ketamine’s time of onset? (IV & IM)
When would this drug be utilized IM?
- IV: 1 min
- IM: 5 min (mostly for pediatric patients)
What is Ketamine’s duration of action?
10-20 min
What is the Vd of ketamine?
3L/kg (large)
S20
Name the pharmacokinetic profile of ketamine:
- Clearance:
- Metabolism:
- Excretion:
- Clearance: high hepatic clearance (1L/min)
- Metabolism: CYP450’s
- Excretion: kidneys
S21
What is the primary metabolite of ketamine and what its its significance?
Norketamine is metabolite (⅓ potency and prolongs analgesia).
S21
In what patient population is ketamine tolerance most often seen?
Burn patients
S21
What is the induction dose of ketamine IV?
What if it is given intramuscularly?
- 0.5 - 1.5 mg/kg IV
- 4 - 8 mg/kg IM
S22
What is the maintenance dosing of ketamine?
- 0.2 - 0.5 mg/kg IV
- 4 - 8 mg/kg IM
S22
What is the subanesthetic/analgesic dose of ketamine?
0.2 - 0.5 mg/kg IV
S22
What is the post-operative sedation and analgesia dosing for ketamine in pediatric cardiac surgery cases?
1-2 mg/kg/hour
S22
What is the neuraxial epidural analgesia dosing of ketamine?
What about intrathecal route?
- 30mg epidural
- 5 - 50 mg via intrathecal/spinal/subarachnoid
S22
Ketamine is a potent sialagogue.
What does this mean for your clinical practice?
- Manage excessive salivary secretions during intubation & watch for coughing/laryngospasm.
What drug and dosing to treat excessive salivary secretions from ketamine administration?
Glycopyrrolate: 0.2mg
S23
You gave ketamine and the patient fell asleep within 30 seconds. If you gave no more doses when would you expect the patient to:
- Wake up?
- Be fully conscious?
- Start remembering things?
*- Wake up *in 10-20 minutes
- Full consciousness in 60 - 90 min
- Amnestic effects should also wear off in 60 - 90 min.
S23
What patient populations is ketamine best used for?
- Acutely hypovolemic patients
- Asthmatics
- Mental health patients
S25
