A New(ish) Vasopressor – Angiotensin II
December 24, 2020
Written by Clay Smith
Spoon Feed
Angiotensin II (Ang-2) is a newer add-on vasopressor agent for patients with refractory hypotension.
Why does this matter?
Refractory hypotension is a challenge. We have the usual pressors, like norepinephrine or vasopressin. Ang-2 is a hormone with an 8 amino acid peptide structure. Bovine-derived Ang-2 has been around for 50 years; a new synthetic version became available in 2017. It is not often used in the ED, but as patients spend more time in the ED prior to moving to the ICU, we may find it necessary to use it in the future. Is Ang-2 a pressor we can add to our arsenal?
A new-ish pressor?
Norepinephrine involves the sympathetic system and binds alpha and beta adrenergic receptors to maintain blood pressure; vasopressin involves the arginine-vasopressin system and binds vasopressin 1 and 2 receptors. Ang-2 involves the renin-angiotensin-aldosterone system and binds angiotensin type 1 and 2 receptors, which is a completely different mechanism to support blood pressure. See the physiology of how it works.
In the ATHOS-3 study, Ang-2 was found to be effective as an add-on agent for raising MAP. And it may allow downward titration of other pressors, like norepinephrine. There was a possible increase in DVT in Ang-2 treated patients. It should be given at a dose of 20 ng/kg/min and titrated every 5 min in increments of 15 ng/kg/min to a maximum dose of 80 ng/kg/min in the first 3 hours and 40 ng/kg/min after this time frame. It has only been studied as an add-on to other pressors; use as a single agent is unknown and probably not advisable at this point. You need to make sure the patient is receiving DVT prophylaxis as well if you add Ang-2. Bottom line: Ang-2 is an add-on pressor for patients with refractory distributive shock that is effective at increasing MAP and may be norepinephrine sparing.
Two of the authors of this review disclosed potential financial conflicts of interest with the pharmaceutical company, La Jolla, that makes human synthetic angiotensin II.
Source
Angiotensin II for the emergency physician. Emerg Med J. 2020 Nov;37(11):717-721. doi: 10.1136/emermed-2019-209062. Epub 2020 Feb 19.
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Another Spoonful
As expected, EMCrit covered ATHOS-3 back in 2017 and has a very recent post on three scenarios when it’s best to give Ang-2. One that struck me as obvious, after I heard it, was patients who take pre-illness ACE inhibitors or ARBs.