Etomidate is the most commonly used rapid sequence intubation, but may not always be the best induction agent. Here are four induction agents for RSI -
Rapid sequence intubation utilizes an induction and paralytic agent. The intent is to blunt the physiologic response of an endotracheal tube being passed and optimizes intubating conditions. Ideally, we want something that is rapid acting with a short duration of action. It would be preferable to select an agent that is cardiovascular, such as etomidate.
This agent is the most commonly used induction agent for RSI. There may be indications for other induction agents. Etomidate lacks anticonvulsant properties, which may warrant midazolam or propofol. For status asthmaticus, ketamine has benefits over other agents given its brochodilatory properties. Expand your drug bank so you have more options specific to the patient in front of you. Here are four induction agents to become familiar within rapid sequence intubation.
Mechanism of action
Nonbarbituate benzylimidazole that acts on GABA receptor
Dosing
RSI: 0.3 mg/kg
Pharmacokinetics
Onset: < 1 minute
Duration: < 5 minutes
T1/2: 75 minutes
Warnings and Precautions
Adrenal insufficiency via 11-b-hydroxylase
Myoclonus
Nystagmus
Insight
Most common induction agent used in RSI given its cardiovascular neutral properties. Single doses of etomidate have not been associated with negative outcomes. Ideal pharmacokinetics with rapid onset and short duration.
Mechanism of action
GABA agonist
Dosing
RSI: 0.2 mg/kg
Pharmacokinetics
Onset: 2 minutes
Duration: 60 minutes
T1/2: 3 hours
Warnings and Precautions
Respiratory depression
Insight
Limited use in the acute setting given its slow onset of action. I've reached for midazolam really in hypotensive patients who are seizing. Aside from that, the other three agents provide suitable kinetics for the indication.
Mechanism of action
GABA agonist
Dosing
RSI: 1 - 2 mg/kg
Pharmacokinetics
Onset: < 1 minute
Duration: < 10 minutes
T1/2: 4 hours
Warnings and Precautions
Respiratory depression
Propofol-Related Infusion Syndrome (PRIS)
Hypertriglyceridemia
Insight
Propofol use is often limited by the patient's hemodynamics as it can induce hypotension and bradycardia. I tend to recommend propofol with reasonable pressures in the setting of seizures with plans to secure the airway. It makes a nice transition from bolus to continuous infusion.
Mechanism of action
NMDA receptor antagonist
Dosing
RSI: 1 - 2 mg/kg
Pharmacokinetics
Onset: < 1 minute
Duration: < 10 minutes
T1/2: 2.5 hours
Warnings and Precautions
Emergence reaction
Cardiovascular abnormalities
More known to cause hypertension/tachycardia, but may induce hypotension in catecholamine depleted patients.
Hypersalivation
Increased intraocular pressure
Insight
Most often the secondary agent will be ketamine. There is a misconception that ketamine should be preferred in hemodynamically unstable patients; this is not true. Ketamine's minor MOA is negative inotropy, which can be dangerous in catecholamine depleted patients. Decompensating patients shouldn't receive full dose of any induction, including ketamine.
More Options, More Patient-Centered Choices
Securing the airway in the emergency department is completed via RSI with an induction and paralytic. The technique optimizes intubating conditions. Etomidate is typically used since it is considered hemodynamically stable. Ideal pharmacokinetics are quick onset and short duration. Midazolam and propofol have anticonvulsant properties compared to etomidate. Ketamine may be preferred for more bronchodilatory effects. The more you expand your drug bank, the options you have to make patient-centered interventions.
Mark Nguyen, PharmD, BCEMP
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