It’s winter and nobody has shoveled the roads; everyone and their mama is slipping. You have a patient with an obvious ankle dislocation and ortho is requesting that you put the patient to sleep so they can yank on the foot in peace without all that bothersome screaming. Ortho is requesting propofol but you are wondering if there is a better agent to use. How come everyone is using propofol or ketamine, why don’t they use etomidate, or even ketofol (that sounds like the perfect drug)???
Before even going down that path, it is important to think about what you want out of sedatives prior to the start of sedation. A nice procedural sedation should have a rapid onset, short duration, analgesia, and minimal hemodynamic effects.
To find such an ideal medication, one should know the mechanism of action, duration of action, dosing, and effects on RR, HR, BP of an assortment of medications I have compiled a list of classic medications seen in the ED below:
|Medication||Analgesia||Amnesia||Concentration||Initial Dose||Subsequent Dose||Onset||Duration||Resp. Rate||Heart Rate||Blood Pressure|
|Etomidate||No||Yes||2mg/ml||0.1mg/kg (up to 10mg)||N/A||<1min||6min||preserved||neutral||-/+|
|Fentanyl/Versed||Yes (Fentanyl)||Yes (Versed)||Fent (50mcg/mL), Versed (1mg/mL)||Fent (0.5-1mcg/kg), Versed: 1-2mg||fent(0.5mcg/kg) push||2-5min||30min||–||–||–|
|Precedex||No||Maybe||4mcg/mL||0.6mcg/kg||0.4mcg/kg/hr||~1hr unless bolus given||~1-2hrs||–||–||–|
From looking at the duration of action and BP effect in the chart above, one might see why no one is using Precedex for something quick and dirty like a shoulder dislocation. Conversely, if you know that the procedure in question is going to take some time (ortho wants to place a cast after the reduction but doesn’t want the patient to move), expect to use a slightly longer-acting combination or anticipate having to give repeated pushes of your sedative and increasing the risk of side effects manifesting.
Keep in mind that this chart is merely a quick guideline and not the whole story. For example, etomidate and ketamine are thought to be hemodynamically stable but the risk of hypotension mid-sedation is always there. Always be aware of what adjuncts you want to have nearby always when preparing for a PSA.
Special Notes: Etomidate – has a rapid onset of action and is relatively short-lasting. Why is it not being used as frequently for procedural sedation? Etomidate is associated with myoclonus (~20% incidence in some studies) and as a result, is thought to be a poor choice in the setting of procedural sedation for orthopedic injuries despite its great hemodynamic profile. It can be great in other situations (think cardioversion)
Ketofol (0.5mg/kg ketamine + 0.5mg/kg propofol) – would a mixture of ketamine (has analgesic effects and better hemodynamic stability) and propofol (good sedative effects and good muscle relaxation) be the perfect ED drug? Is this the messiah for whom we have been searing?
Turns out the answer is not quite. Multiple studies have been done comparing ketofol to ketamine or propofol. In recent literature, no clinically significant difference has been found between ketofol and the other two meds when reviewing rates of respiratory depression, hypotension, or procedural success.