Tuesday, March 25, 2014

Extravasation of noncytotoxic medications in the ED

I must admit that I rarely read the primary publication in the pharmacy world (Pharmacotherapy) because of its general lack of anything new or interesting.  Ground breaking clinical research is simply not published in this journal, but it does have excellent review articles that are so over the top, hyper-detail oriented and nauseatingly thorough and make obsessive clinical pharmacists drool.  The latest review (Management of Extravasation Injuries: A Focused Evaluation of Noncytotoxic Medications) is a prime example. But all sarcastic ranting aside, this is an excellent article for a number of reasons. For us in the ED, it’s not so much about reviewing general vasopressor type extravasation (whoopee!), but rather remembering that many other drugs we administer routinely in the ED can cause devastating extravasation due to either hyperosmolarity or acidic/alkaline properties.  And remember, we do administer a number of these medications, undiluted in small peripheral lines.

Table 4 in the manuscript is the case and point example (and I wish the authors expanded further on these medications, not the tried an true vasopressor/calcium stuff).  But from that list here are the agents you may find familiar:

Aminophylline (10 mOsm/L) – the only hypotonic med on the list
Dextrose 50% Water (D50W) – 2520 mOsm/L
Mannitol 20% - 1369 mOsm/L
Hypertonic saline 3% - 1026 mOsm/L
Hypertonic saline 23.9% - 8008 mOsm/L!
Sodium Bicarb 8.4% - 2000 mOsm/L
Propylene glycol – a hyperosmolar vehicle found in various medicaions in the ED, namely: Etomidate, lorazepam, diazepam, nitroglycerin, digoxin
Phenytoin – pH 10-12, > 700 mOsm/L
  
The paper discusses hyaluronidase as an option to manage hyperosmolar extravasations.  But again, the critical information is found at the bottom footnote of Table 4, which is how the heck to administer to a patient (I mean its great to know the mechanism and kinetics and all, but administration tends to be an often overlooked, unsexy factor).

“Hyaluronidase is commonly diluted to a 1:10 ratio (0.1 ml reconstituted hyaluronidase, 0.9 ml normal saline). A series of five injections of 0.2 ml is then administered with a tuberculin syringe until all 15 units are given. Dosage is expressed in turbidity reducing units (TRUs ). One TRU will allow the dispersion of volumes up to 50 ml from the subcutaneous compartment.”

I fortunately have not had any experience with this in the ED, so can’t comment on the ease or feasibility of effectively determining the volume of extravasated drug and subsequent estimation of dose.  I would imagine it is more of a guess and empiric dose than anything.

I would encourage any ED pharmacists to review the article, since it is quite a good review, but be ready to do some heavy reading and digging into the references for the best outcomes.