Emergent FFP for Angioedema?

You get a call from an ER nurse that they new FFP emergently on a patient in the ER. The patient's tongue and face is swelling to the point of respiratory compromise. You don't have any blood type on file so you tell the nurse, and decide that it's so emergent that you'll have to thaw AB plasma and give it emergently. 

What was happening to this patient? Why was this such an emergency? What is FFP going to do to help this patient in this situation?

Angiotensin Converting Enzyme (ACE)

 Millions of people in the world have diagnosed hypertension and may be prescribed an Angiotensin Converting Enzyme (ACE) inhibitors to control their elevated blood pressure. An uncommon side effect of ACE inhibitors includes angioedema, in which fluid buildup and swelling occurs underneath the skin in certain areas. Inhibiting Angiotensin Converting Enzyme can lead to a build up of an enzyme known as bradykinin, which is a potent vasodilator, but also leads to increased vascular and capillary permeabilty. This allows fluids to leave the space they should occupy and accumulate in other areas in which they shouldn't. This effect is known as ACE inhibitor-induced angioedema or ACEI-IAE.

ACEI-IAE typically presents as an emergency as airways and respiratory systems can quickly become compromised by excessive tongue, face, neck, etc., swelling. Initial treatment will include discontinuation of the drug, and potentially antihistamines, steroids, epinephrine, IVIG, etc. This may not work for all patients, however. 

How Does FFP Help with Angioedema?

FFP has been used successfully in patients who do not respond to other treatments. Some patients respond quite rapidly after FFP transfusion and regain respiratory control. The idea behind FFP administration is that FFP contains ACE, sometimes referred to as Kininase II, as it's an enzyme that can break down Bradykinin. This immediate addition of Kininase II from FFP transfusion helps to breakdown the excessive bradykinin that has accumulated due to ACE inhibitor use. This is why so many patients will see a very rapid improvement post FFP administration.