Mechanism of Action
Ketamine causes intense amnesia by inhibiting glutamine at the NMDA receptors in the thalamocortical and limbic central nervous system (CNS).
- The heart rate, blood pressure, and cardiac output increase due to the sympathetic effects of ketamine through stimulating CNS outflow.
- This leads to fewer reuptake catecholamines from outside the cell which causes a rise in these chemicals within neurons as well as between them.
Dose
1 to 2 mg/kg (common, 100-200 mg)
Onset
- Onset: ~ IV 30 seconds IM 3-4 minutes
Duration
- Duration: 5-10 minutes
Adverse Effects
- Hypertension
- Tachycardia
- Nausea & Vomitting
- Emergence phenomenon
Ketamine Impact on Hemodynamics
Blood Pressure (BP) | Heart Rate (HR) | Cardiac Output (CO) | Intracranial Pressure (ICP) |
---|---|---|---|
↑ Increased | ↑ Increased | ↑ Increased | ↔/ ↓ No Change/Decrease |
Literature Review
Author, year | Design/ sample size | Intervention & Comparison | Outcome |
---|---|---|---|
Lyons, 2015 | Cohort study/ n=261 | Etomidate+ Succinylcholine (Group 1) vs Fentanyl+ ketamine+ rocuronium (Group 2) | Significantly better laryngeal views with fentanyl/ketamine/rocuronium group 100% first attempt intubation with fentanyl/ketamine/rocuronium group ↑ post-intubation MAP+ HR with etomidate + succinylcholine |
Bruder, 2015 | Cochrane Review | Etomidate Midazolam Propofol Ketamine | There was no difference in mortality, hospital LOS, duration of ventilation, and duration of vasopressors Etomidate associated with ↑ ACTH and ↓ in cortisol level |
Jabre P, 2009 | RCT/ n=469 | Etomidate 0.3 mg/kg vs Ketamine 2 mg/kg | No difference in intubating condition, SOFA score, 28-day mortality, Ventilator free days, vasopressor support, or GCS |
Comments by ED Physician Attendings
Pro’s | Con’s |
“Ketamine has some bronchodilatory properties and can be useful if intubating for asthma angioedema, airway narrowing from anaphylaxis, infection or malignant processes are the typical examples.” | “The dose should be greatly reduced in shock states- most notably hypovolemic shock as it is a direct myocardial depressant. There are some case reports of cardiac arrest when full induction doses of ketamine are pushed in these patients. In those patients, I will push 10mg at a time until dissociation occurs (usually around 0.2-0.3 mg/kg in my experience).” |
Comment
- Ketamine has an analgesic effect unlike other induction agents
- Ketamine has properties that treat seizures by decreasing excitation via inhibtion of NMDA receptor