What exactly does anaphylaxis mean?

[CBG23]

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So, I am a bit confused about the term anaphylaxis. Based on one source it refers to a systemic manifestation of a type I hypersensitivity reaction - basically, with all the signs and symptoms you would expect from a local Type I reaction (such as hives, swelling, and itchiness). Based on another source, it refers to a systemic increase in vascular permeability because of a type I reaction leading to a drop in blood pressure, tissue hypoxia, etc. So which of the two is it? Or is there a more precise/ accurate definition out there?

 

[aggie08]

So, I am a bit confused about the term anaphylaxis. Based on one source it refers to a systemic manifestation of a type I hypersensitivity reaction - basically, with all the signs and symptoms you would expect from a local Type I reaction (such as hives, swelling, and itchiness). Based on another source, it refers to a systemic increase in vascular permeability because of a type I reaction leading to a drop in blood pressure, tissue hypoxia, etc. So which of the two is it? Or is there a more precise/ accurate definition out there?

The second definition you give is more descriptive of Anaphylactic Shock. You are on target with the definition of anaphylaxis being a Type I Hypersensitivity Reaction. Basically the body just becomes overwhelmed with degranulated Mast cells, causing all the typical allergic-reaction symptoms (hives, swelling, itching, difficulty breathing, etc.) When the reaction starts including major vasodilation with severe blood pressure drops (to the point of loss of consciousness or seizures) then it is referred to as Anaphylactic Shock.

I'm not sure if there is a hard dividing line between the two, because as I understand it you have some degree of increased vascular permeability and vasodilation even with less severe episodes of anaphylaxis. So, basically everything you said is correct and the definition kind of encompasses all the descriptive factors you listed up there.

Eh, I hope that makes at least a grain of sense.

 

[PBandJ]

The second definition you give is more descriptive of Anaphylactic Shock. You are on target with the definition of anaphylaxis being a Type I Hypersensitivity Reaction. Basically the body just becomes overwhelmed with degranulated Mast cells, causing all the typical allergic-reaction symptoms (hives, swelling, itching, difficulty breathing, etc.) When the reaction starts including major vasodilation with severe blood pressure drops (to the point of loss of consciousness or seizures) then it is referred to as Anaphylactic Shock.

I'm not sure if there is a hard dividing line between the two, because as I understand it you have some degree of increased vascular permeability and vasodilation even with less severe episodes of anaphylaxis. So, basically everything you said is correct and the definition kind of encompasses all the descriptive factors you listed up there.

Eh, I hope that makes at least a grain of sense.

I think the poster above pretty much hit the nail on the head. Anaphylaxis is synonymous with "type I hypersensitivity reaction", whereas anaphylactic shock refers to an extreme case where you have anaphylaxis / Type 1 HS with massive systemic vasodilation & extreme bronchoconstriction. It's important to remember that there is a sliding scale - not all anaphylaxis manifests to the same extent, but it's still called anaphylaxis or type 1 hypersensitivity. The extent of anaphylaxis is dependent on several factors, including the amount of allergen present, the level of sensitization of the patient, and even other factors such as medication or other conditions already present in the patient.

 

[werd]

anaphylaxis is a systemic type 1 hypersensitivity. getting a couple hives isn't anaphylaxis, but getting covered in them is. as pointed out above, the whole blood pressure drop definition sounds like anaphylactic shock, which is a subcategory of anaphylaxis.

 

[ArcGurren]

Yeah pretty much what's been said. Anaphylaxis = Type I hypersensitivity reaction with subtypes of systemic anaphylaxis (the shock that you're referring to with increased vascular permeability and exudates etc) and localized anaphylaxis (hives and such).

 

[Dirt]

Typically anaphylaxis is defined as a type 1 hypersensitivity reaction involving at least two organ systems. Isolated hives is not anaphylaxis, hives plus hypotension is, for example. Shock is defined separately and anaphylactic shock is just shock due to anaphylaxis.