Etomidate
Ultrashort-acting carboxylated imidazole anesthetic administered intravenously to induce unconsciousness, usual dose 0.3 mg/kg IV
Directly inhibits adrenal 11-beta- hydroxylase (enzyme responsible for cortisol biosynthesis)
↓ Adrenal cortisol production
↓ Serum cortisol available for stress response
Transient adrenal steroid insufficiency
↑ Morbidity & mortality in trauma/critically ill patients (Contraindicated in sepsis)
Inhibits nitric oxide signaling
Transient cerebral vasoconstriction
↓ Cerebral blood flow
↓ Oxygen delivery to brain
↓ Cerebral metabolic rate
Suppression of electrical activity in brain
Flat electroencephalogram
Binds to GABAA
(inhibitory CNS neurotransmitter) receptor
Authors:
Cindy Chang
Ran (Marissa) Zhang Reviewers:
Melissa King
Brooke Fallis
Julia Haber*
* MD at time of publication
Abbreviations:
• CNS – Central Nervous
System
• GABAA- Gamma-
aminobutyric acid type A • TRPA1- Transient
receptor potential type A1
Higher selectivity for specific GABAA receptor subtypes compared to other induction agents
Positively modulates GABAA receptor (GABAA receptor activated at lower concentrations of GABA )
↓ Cerebral blood volume
Activation of fewer GABAA receptor subtypes in neurons and cardiovascular structures compared to other induction agents
↓ Intracranial pressure ↑ Hemodynamic stability
(minimal changes in blood pressure or heart rate)
Myoclonus (brief, involuntary, irregular muscle twitch)
↑ Spontaneous CNS neuron firing to skeletal muscle
Prolonged opening of GABAA receptors (acts as ion channel for chloride)
Inhibits activity of nerve cells in the reticular activating system
Activation of peripheral nociceptor receptors
↑ Involuntary muscle contractions
Influx of chlorideàHyperpolarization of nerve membranes in reticular activating system
(brainstem neuronal network that regulates arousal and sleep- wake transitions)
Depression of arousal & loss of consciousness
Induction of general anesthesia
(no analgesic effect)
Direct activation of TRPA1 cation channels (key receptor in pain pathway)
Stinging pain with injection
(Treat with co-administration of local anesthetic)
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published July 9, 2022 on www.thecalgaryguide.com