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Created February 7, 2021, last updated almost 4 years ago.
Collection: 136, Score: 974, Trend score: 0, Read count: 1338, Articles count: 2, Created: 2021-02-07 23:27:39 UTC. Updated: 2021-02-08 00:09:43 UTC.Notes
Etomidate (Amidate™) is short-acting intravenous anesthetic agent first developed in 1964. It is available and used in the United Kingdom, Europe, New Zealand, United States, but not Australia.
Advocates highlight etomidate's hemodynamic stability when used for induction. Critics point to the well-established adrenocortical suppression, and wide-range of suitable alternatives (propofol, ketamine, thiopentone) in trained hands.
A. Physiochemistry
- Carboxylated imidazole
- 2 isomers - only R(+) hypnotic
- Haemodynamic stability, minimal respiratory depression, cerebral protection, wide margin of safety.
- Originally formulated in propylene glycol (painful), now in soybean lipid.
B. Pharmacokinetics
- Dose - 0.3 mg/kg (0.1-0.4 mg/kg)
- Absorption - IV
- Distribution - 4 L/kg
- Protein binding - 75% (like thiopentone)
- Onset 30-60s ; Offset
- Metabolism - alpha1 ½ 2.5m, alpha2 ½ 30m, tß½ 3.5h; hepatic ester hydrolysis of ester side chain.
- Clearance - 20 mL/kg/min
C. Pharmacodynamics
- Mech - probably by GABAa receptors.
- CNS - hypnosis; no analgesic action; ⇣ CBF and CMRO2
- CVS - stable; may have slight dec MAP 15% due to ⇣ SVR.
- Resp - minimal; sometimes brief hypoventilation or apnoea post-induction.
- Endo - adrenocortical suppression - inhibits 11ß-hydroxylase (11-deoxycortisol → cortisol). Temporary & reversed by vit C.
- ⇡ ICU mortality when used for sedation.
- SEs - excitatory phenom, involuntary muscle movement (50%), PONV (30%), thrombophlebitis (20%), pain on injection.
Daniel Jolley
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Collected Articles
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Prehospital hypoxia and hypotension increase morbidity and mortality in head-injured patients. Etomidate is a sedative agent with increasing use for emergent rapid-sequence intubation (RSI) because of its favorable hemodynamic profile. This prospective, observational study documents the authors' preliminary experience with etomidate as part of an aeromedical RSI protocol. ⋯ An improvement in SBP after RSI with etomidate was observed (123 mm Hg to 136 mm Hg, p = 0.011) with a 9% incidence of hypotension, defined as a decrease in SBP to 90 mm Hg or less. Graphic analysis of individual SBP-time plots reveals hemodynamic stability, especially in patients with lower initial SBP values. These data suggest that the use of etomidate as part of a prehospital RSI protocol is associated with hemodynamic stability and a low incidence of hypotension.
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Anesthesia and analgesia · Sep 1985
Randomized Controlled Trial Comparative Study Clinical TrialEtomidate versus thiopental for induction of anesthesia.
Hemodynamic changes and side effects of anesthesia induction with etomidate or thiopental were evaluated in 83 ASA class I or II patients. Patients were randomly assigned to one of 12 groups according to pretreatment drug (fentanyl, 100 micrograms, or normal saline intravenously), induction agent (etomidate, 0.4 mg/kg, or thiopental, 4 mg/kg), and maintenance anesthetic technique (isoflurane-oxygen, isoflurane-nitrous oxide-oxygen, or fentanyl-nitrous oxide-oxygen). The purpose of this experiment, of factorial design, was to evaluate the combined effects of two or more experimental variables used simultaneously and to observe interaction effects. ⋯ Patients in whom anesthesia was induced with etomidate had a greater incidence of pain on injection and myoclonus and a lesser incidence of apnea than patients in whom anesthesia was induced with thiopental. Fentanyl pretreatment significantly decreased the incidence of pain on injection and myoclonus, but it increased the incidence of apnea when anesthesia was induced with etomidate. The incidence of postoperative nausea and vomiting was similar after thiopental and etomidate and was unaffected by fentanyl pretreatment. (ABSTRACT TRUNCATED AT 250 WORDS)