Test 1: Etomidate Flashcards
What are the uses for Etomidate?
-Air transport
-Emergencies
-Induction for unstable patients
-Induction for ECT (because it is less anti-convulsive than propofol or thiopental)
What are the CNS effects associated with the use of Etomidate?
-Dose dependent sedative effects
-Potent cerebral vasoconstrictor (dec ICP)
-Decreases CBF and CMRO2
-Maintains cerebral blood vessel responsiveness to CO2 levels
-Decreased IOP
-Anticonvulsant, EEG slowing to burst suppression, sedation, hypnosis
-Myoclonus with induction doses (10-60% of patients) that can be blocked by opioids or benzos
What are the CV effects associated with the use of Etomidate?
-Minimal Cardiac depression
-Minimal vasodilation (MAP may decrease 15%)
The cardiac stable induction agent
Doses > 0.3 mg/kg produce significant decreases in BP and CO.
What are the Respiratory effects associated with the use of Etomidate?
Dose dependent respiratory depression, but less than other IV agents
-Increased RR, decreased MV
-Usually preserves airway reflexes (can be used for MAC)
-Apnea when utilized with opioids
-No effect on bronchial tone (no histamine release)
What are the misc effects associated with the use of Etomidate?
-Nausea & Vomiting (Vomidate)
-Pain on injection/thrombophlebitis
-Adrenal steroid suppression (reduced with new analogues) for 4-8 hours after induction
No intrinsic analgesia
What is important to know regarding Etomidate and Adrenal Suppression?
-Potential for increased mortality in critically ill patients
-1983 study concluded adrenal suppression with continuous infusion (weak data)
-Occurs due to the suppression of cortisol production due to suppression of the synthesizing enzyme 11β-Hydroxylase in the adrenal cortex
-Current developmental modifications to remove endocrine effects
-It has been suggested that an alternative sedative induction agent should be considered for use in rapid sequence intubation in septic patients on multiple vasopressors or with abdominal source of infection.
Why does myoclonus occur with Etomidate injection?
Sudden, generalized, asynchronous muscle contractions that can affect many muscle groups or a single muscle.
-Occurs in 10-60% of patients
Theories:
-r/t brainstem activity of deep cerebral structures and CNS stimulation
-Alteration in the balance of inhibitory and excitatory influences on the thalamocortical tract
Can prevent with pretreatment using small doses of dexmedetomidine, midazolam, rocuronium, or lidocaine
Which IV anesthetic has the greatest selectivity for GABA A Receptors and has the fewest relevant interactions with other ion channels/receptors? (Blue box!)
Etomidate
What are the pharmacokinetics associated with Etomidate?
-Onset: 30-60 sec (rapid awakening occurs 5-15 minutes after bolus due to redistribution)
-76% protein bound
-Chemical Structure: Imidazole derivative (lipophilic)
-Metabolism: Liver CYP & Plasma esterases (Ester Hydrolysis)
-1/2 life = 2-6 hours
What is the induction dose for Etomidate (Adults and Children > 10)?
0.2 - 0.5 mg/kg
-Usually 0.3 mg/kg
What is the MOA of Etomidate?
-Allosterically binds at the GABA-A subunit in the brainstem and cortex, and increases the receptor’s affinity for GABA.
-Mimics the inhibitory effects of GABA.
-Has the highest selectivity for GABA and has less interaction with other receptors.
When is Etomidate contraindicated?
-Known hypersensitivity
-Adrenal Suppression
-Acute Porphyrias
Etomidate is hemodynamically stable, except for in which conditions?
Patients with high sympathetic tone such as those with shock, intoxication, or drug withdrawal can have a precipitous drop in blood pressure even when etomidate is used to induce anesthesia.
What is the induction dose for Etomidate? (Katzung)
0.2 - 0.3 mg/kg IV
What is the DOA for Etomidate (Katzung)?
3-8 min
