In this episode I’ll:
1. Discuss an article about using dexmedetomidine for agitated delirium when haloperidol doesn’t work.
2. Answer the drug information question “Should I use a loading dose when initiating a dexmedetomidine infusion?”
3. Share a resource I created for calculating the time to wait after the last dose of a non-vitamin K antagonist oral anticoagulant before a low or high risk surgical procedure.
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Lead author: Genís Carrasco
Published online February 2016 in the journal Critical Care Medicine
Agitated delirium in the ICU setting complicates the management of critically ill patients.
The study was a non-randomized controlled trial in a 13 bed medical-surgical ICU setting. 132 consecutive ICU patients with a diagnosis of agitated delirium were included. Numerous exclusion criteria were applied including history of substance abuse, Parkinson’s, bradycardia, and QTc interval prolongation at baseline.
Despite the exclusion criteria, only 18 of 154 patients evaluated were excluded for these reasons. This is a very low number and speaks well to the generalizability of the results.
Haloperidol was titrated as follows:
All patients received IV haloperidol bolus doses of 2.5–5 mg, with intervals of 10–30 minutes, until control of agitation (RASS score, 0 to −2) or until reaching the maximum cumulative daily dose of 30 mg.
The patients were then split into “responder” and “non-responder” groups. Patients in the responder group were given a haloperidol infusion of 0.5-1mg/hr to maintain a RASS of 0. Patients in the non-responder group were given a dexmedetomidine infusion starting at 0.2 mcg/kg/hr titrated to a maximum of 0.7 mcg/kg/hr to maintain a RASS of 0.
86 patients responded to haloperidol titration and were given a haloperidol infusion. 46 patients were non-responders and were given a dexmedetomidine infusion. Patients in the dexmedetomidine group had a satisfactory sedation level 92% of the time, compared to 59% for the haloperidol group. This difference was statistically significant.
Although 2 patients in the haloperidol group had QTc lengthening above 440 msec, the difference between groups did not reach statistical significance. The only adverse effect that was statistically significant between groups was over-sedation, which occurred only in the haloperidol group in 10 patients, and required non-invasive mechanical ventilation in 8 patients.
The authors concluded that
Dexmedetomidine shows to be useful as a rescue drug for treating agitation due to delirium in non-intubated patients in whom haloperidol has failed, and it seems to have a better effectiveness, safety, and cost-benefit profile than does haloperidol.
At my institution most patients with agitated delirium are managed with atypical antipsychotics. Dexmedetomidine is used occasionally but I can’t remember ever using a continuous infusion of haloperidol.
Drug information question
Q: Should I use a loading dose when initiating a dexmedetomidine infusion?
The risk of bradycardia from dexmedetomidine may be significantly higher when a loading dose is used. The risk is almost never worth the few minutes of faster sedation that a loading dose provides. Because of this I do not use a loading dose when initiating a dexmedetomidine infusion.
In the past I’ve used a reference by IPRO for deciding how long to wait for a surgical procedure after stopping apixaban, dabigatran, or rivaroxaban. The IPRO authors suggest waiting 2 to 3 medication half-lives for low bleeding risk procedures and 4 to 5 half-lives for high bleeding risk procedures.
The reference has some inaccuracies when it comes to calculating half-lives, so I have created my own version in the form of an interactive calculator. The calculator takes into account a patient’s age & renal function, and displays the length of time needed to wait for 2, 3, 4 or 5 half-lives for each anticoagulant. You can find the calculator at pharmacyjoe.com/NOAC.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.