In this episode I’ll:
1. Discuss an article about trends in use of midodrine in the ICU.
2. Answer the drug information question “Should phentolamine be used to treat dobutamine extravasation?”
3. Share a resource for targeted medication safety best practices for hospitals.
Article
Trends in Use of Midodrine in the ICU: A Single-Center Retrospective Case Series
Lead author: Mahrukh Rizvi
Published in Critical Care Medicine March 2018
Background
Midodrine is an oral alpha-agonist that has been used off-label as a way to wean otherwise stable ICU patients off of vasopressor therapy. While some studies support the efficacy of midodrine for this purpose, side effects and complications are less well known. The authors of this article describe the trends in use and reported side effects and complications of midodrine in multidisciplinary ICUs of a tertiary care institution.
Methods
The study was a single-center retrospective case series spanning 5 years at the medical and surgical ICUs at Mayo Clinic, Rochester. Any adult patient who received midodrine for hypotension was included.
Results
During the study period, more than 1000 patients were initiated on midodrine. Slightly more than half of the patients were in a surgical ICU.
There were 2 distinct patterns of midodrine use:
1. As an oral agent to allow the weaning of IV vasopressors.
2. As an oral agent to be introduced early prior to vasopressor initiation to either spare the need for IV vasopressors or decrease the dose and duration of IV vasopressors.
Of the patients who were on IV vasopressors, at 24 hours after initiation of midodrine, 48% were weaned off vasopressor infusion.
Of the patients who were not on IV vasopressors, 90% remained off.
Doses of midodrine ranged from 5 mg po every 8 hours to 30 mg po every 8 hours, and there was no set protocol to decide which dose to use.
Asymptomatic bradycardia (heart rate < 50 beats/min) occurred in 15% of patients who received midodrine. Of those patients, 60% also had a heart rate < 40 beats/min.
Two patients developed bowel ischemia after initiation of midodrine that prompted discontinuation of midodrine in one case.
Conclusion
The authors concluded:
Our results suggest that midodrine is being increasingly used as an adjunct to increase mean arterial pressure and facilitate weaning of vasopressors in the ICU. Prospective trials are required to further establish the appropriate timing, efficacy, safety, and cost-effectiveness of midodrine use in ICU patients.
Discussion
Until prospective evidence is reported on the safety of midodrine as a vasopressor sparing therapy, this study represents the best information available. Asymptomatic bradycardia is a common but otherwise benign side effect of midodrine. In an ICU setting, this is easily detected by routine monitoring.
The most concerning unanswered question with using midodrine as vasopressor sparing therapy is: When and how do you wean the midodrine off?
I’ve yet to see any study of midodrine for weaning IV vasopressors that include a description of a tapering schedule. Due to the 3-4 hour half-life of midodrine, it can likely be tapered off quickly. However, the decision to taper would likely be made in a general medical unit – where there is less ability to closely monitor a patient’s response to a reduction in midodrine dosage.
Drug information question
Q: Should phentolamine be used to treat dobutamine extravasation?
A: Yes
Also thought of as an inotrope, the L-isomer of dobutamine has alpha1-adrenergic effects. There is a case report of dermal necrosis from dobutamine extravasation. In this report, the authors did not give phentolamine only because of the time that had lapsed between when the extravasation happened and when it was recognized. For dobutamine extravasation that is caught early and before necrosis occurs, I use phentolamine in the same manner as I would for a vasopressor extravasation.
Resource
The resource for this episode is the ISMP guidelines on Targeted Medication Safety Best Practices for Hospitals. These guidelines were developed to identify, inspire, and mobilize widespread, national adoption of best practices for specific medication safety issues that continue to cause fatal and harmful errors in patients, despite repeated warnings in ISMP publications.
Some of the issues addressed in the guidelines are:
- VinCRIStine (and other vinca alkaloids) inadvertently administered by the intrathecal route
- Accidental daily dosing of oral methotrexate intended for weekly administration
- Inappropriate use of fentaNYL patches to treat acute pain and/or patients who are opioid-naïve
- Serious tissue injuries and amputations from injectable promethazine use
Get an example of the 7 questions I use to lead a topic discussion on vasopressors in my free download area. It’s download #17.
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.
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