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Type 1 Hypersensitivity: Anaphylaxis

pandr2885 — 2024-03-06 18:10:10 UTC

Overview:

pandr2885 — 2024-03-06 18:12:45 UTC

Type 1 hypersensitivity is an immediate and traditional reaction involving the production of IgE antibodies due to the presence of a specific antigen. It results in mast cell degranulation and the release of inflammatory mediators. There are two stages involved in its response–sensitization and the effect stage. In the sensitization stage, the host makes contact with the antigen. Following this stage, in the effect stage, the pre-sensitized host is re-introduced to the antigen, which leads to immune response or more severely anaphylaxis.

Pathophysiology:

pandr2885 — 2024-03-06 18:13:42 UTC

Cellular pathophysiology: The initial exposure happens when the antigen is exposed to the T cells. The T-cells signal B-cells to produce IgE. After second exposure, IgE antibodies bind with mast cells which causes mast cell degranulation. This causes the release of histamines, leukotrienes, and other cellular mediators. The response to the release of the cellular mediators is inflammation.

Tissue or organ level pathophysiology: The tissues and organs affected are dependent on the host. The release of the cellular mediators causes vasodilation, increased vascular permeability, bronchoconstriction, and smooth muscle contraction. This can affect the organs of the GI, respiratory, cardiovascular, and integumentary systems. After the cellular mediators are released, immune cells come to the area and work to rid of the foreign invaders. This is seen when you find neutrophils, basophils, eosinophils, in the mucosal and submucosal lining.

Risk factors:

pandr2885 — 2024-03-06 18:13:58 UTC

previous anaphylaxis
allergies (foods, medications, environment)
genetics
asthma
heart disease
mastocytosis (irregular accumulation of a certain type of white blood cell)

Clinical Manifestations:

pandr2885 — 2024-03-06 18:14:59 UTC

GI: nausea, vomiting, diarrhea, abdominal pain
Skin: urticaria(Hives), itching, angioedema
Respiratory: rhinitis, bronchospasm, laryngeal edema
CV: hypotension, tachycardia, dysrhythmias

Expected therapeutic management:

pandr2885 — 2024-03-06 18:17:29 UTC

Therapeutically, prompt intervention with an adrenergic, more specifically epinephrine, can reverse symptoms of anaphylaxis. Adrenergics intervene symptoms of anaphylaxis by constricting blood vessels, relaxing airway muscles, and sometimes by stabilizing blood pressure. Following acute treatment, ongoing therapeutic management may help to reduce and prevent delayed or recurrent reactions. Because anaphylaxis affects multiple organ systems simultaneously, it is best to keep in mind to not delay the injection of epinephrine. Prompt intervention can reduce the likelihood of severe, life-threatening complications. Listed are some examples of the expected therapeutic management:

Adrenergics:

Epinephrine
- Epinephrine can be administered SubQ, IM, IV
- EpiPens are administered in the anterolateral thigh
  - adult dose (patients >30 kg) = 0.3 mg
  - pediatric dose (patients 15-30 kg) = 0.15 mg
- Can also be administered via inhalation (racemic epinephrine) or spinal (adjunct in the prolongation of anesthesia)
- no absolute contraindications to epinephrine administration for an anaphylactic shock-- use immediately!
Bronchodilators (short-acting beta-adrenergic)
- Bronchodilators are typically used for patients with chronic obstructive pulmonary disease (COPD) or asthma, but people who have either of these are at an increased risk of having an anaphylactic reaction
  - e.g. Albuterol/Ipratropium bromide
Antihistamines (alpha-adrenergic)

Other forms of therapeutic management:

Supplemental O2
Diphenhydramine (Trade name: Benadryl)
- given only if patient is able to swallow, A&Ox4

References:

pandr2885 — 2024-03-13 00:47:35 UTC

Abbas, M. (2023a, July 17). Type I hypersensitivity reaction. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK560561/#:~:text=As%20previously%20stated%2C%20the%20most,circulatory%20failure%20(distributive%20shock).

Davis, F. A. (2019). Davis’s Drug Guide Online + App | DrugGuide.com. Drugguide.com; FA DAVIS. https://www.drugguide.com/ddo

Roger’s J. (2023) McCance & Huether’s Pathophysiology: The Biologic Basis for Disease in Adults and Children, Ninth Edition. Elsevier.

Vitte, J., Vibhushan, S., Bratti, M., Montero-Hernandez, J. E., & Blank, U. (2022). Allergy, Anaphylaxis, and Nonallergic Hypersensitivity: IgE, Mast Cells, and Beyond. Medical principles and practice : international journal of the Kuwait University, Health Science Centre, 31(6), 501–515. https://doi.org/10.1159/000527481

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ahwan1323 — 2024-03-13 12:47:51 UTC

pandr2885 — 2024-03-14 19:19:06 UTC

2024-03-17 19:55:02 UTC

https://my.clevelandclinic.org/health/diseases/8619-anaphylaxis