Ketamine

Question 1

Presentation

Answer 1

200mg in 2ml glass ampoule

Question 2

Pharmacology

Answer 2

Anaesthetic agent with analgesic properties at lower doses.
Exact mechanism of action is unclear, but primarily works as an antagonist on NMDA receptors. Ketamine may also interact with opioid, muscarinic and other receptors. Produces a trance-like dissociative state with amnesia, with preservation of laryngeal and pharyngeal reflexes.

Question 3

Indications

Answer 3

• intubation
• pain relief
• sedation- agitation
  - patient movement during CPR

Question 4

Contraindications

Answer 4

• suspected non-traumatic brain injury with severe hypertension (SBP >180)

Question 5

Precautions

Answer 5

• may exacerbate cardiovascular conditions (eg. uncontrolled hypertension, stroke, recent MI, cardiac failure) due to effects on HR and BP

Question 6

Side effects

Answer 6

1. CV: hypertension, tachycardia
2. CNS: emergence reactions (eg. vivid dreams, restlessness, confusion, hallucinations, irrational behaviour); increased skeletal muscle tone (may resemble seizures)
3. Respiratory: transient respiratory depression and apnoea (rare)
4. GI: nausea and vomiting
5. Other: injection site pain, lacrimination, hypersalivation, diplopia, nystagmus

Question 7

Route

Answer 7

• IV: dilute ketamine 200mg/2ml to 20ml with 18ml normal saline (10mg/ml). Administer IV doses slowly (over at least 1 minute); rapid administration may result in respiratory depression and enhanced hypertensive response
• IM: (do not dilute)
• IN: (add 0.1ml to required amount to allow for dead space in MAD)

Question 8

Special notes

Answer 8

Onset of action:
- IV 30 seconds
- IM 3-4 minutes
-IN 5 minutes
Peak:
- IN 20 minutes
Duration:
- IV 5-10mins (anaesthesia)
- IM 12-25 mins
- IN 45 mins

Emergence reactions associated with ketamine administration for analgesia in adult patients can be managed with midazolam. Consult with RCH is required to administer midaz to paediatric patients.