AS belongs to type I allergic reactions. Upon repeated contact of the sensitized organism with the allergen, the latter binds to fixed on the surface of tissue mast cells (MC) and circulating basophils IgE-Am.

2. MCs are located mainly in the submucosal layer and the skin next to the blood vessels. The interaction between IgE and the allergen on the surface of inflammatory mediators, including histamine.

3. Released from the MC leads to the inclusion of a complex of reactions, the final stage of which is the release of multiple MCs, histamine acts on the H1 and H2 receptors of target organs: smooth muscle, secretory cells, nerve endings, which leads to an increase and increase in vascular permeability, bronchospasm, hyperproduction of mucus . Prostaglandins, leukotrienes, and other BASs synthesized upon MC activation cause similar changes.

4. An increase in the concentration of histamine and other mediators of allergy in the serum leads to (1) dilatation of small-caliber vessels, (2) increased permeability of the vascular wall, and the release of the liquid portion of blood into the tissue.

5. Histamine causes a spasm of pre- and postcapillary sphincters, with pre-capillary sphincters rapidly relaxing and additional volume of blood entering the capillary zone, leading to the exit of fluid into the tissue. The capacity of the vascular bed increases sharply and the volume of circulating blood decreases.

6. Decreased vascular tone leads to a sharp drop in vascular resistance, a consequence of this is a reduction in blood pressure - "peripheral vascular collapse".

7. Decrease in blood pressure leads to a decrease in venous return of blood to the heart, and, consequently, the shock volume of the heart decreases. The minute volume of the heart is first compensated for by tachycardia, then it also decreases.

8. The fall of blood pressure leads to a violation of blood flow in vital organs (heart, kidney, brain, etc.), and the release of pressor hormones decreases.

The peculiarities of AS consist in the fact that with other types of shock, when the volume of circulating blood decreases, adrenaline is released, causing vasospasm, an increase in peripheral vascular resistance and maintenance of arterial pressure; in case of anaphylaxis, this compensatory mechanism does not work in connection with the development of acute peripheral vascular collapse.

Patients who are taking ß-blockers have increased incidence and severity of anaphylaxis and can develop a paradoxical response to epinephrine (Anaphylaxis By : O. Ahmadi, MD. Professor Assistant of Esfahan medical School, Emergency Department of Al-Zahra Hospital.http://slideplayer.com/slide/5858566/)

Asystole after the first dose of ceftriaxone. Am J Emerg Med 2012; 30(7):1321. 10. Ernst MR, van Dijken PJ, Kabel PJ, Draaisma JM.

Asystole after the first dose of lansoprazole

Article in The American journal of emergency medicine 32(10) · April 2014

DOI: 10.1016/j.ajem.2014.03.051 

Dear Dr Vaikhanskaya,

Thank you so much for your detailed reply and the literature recommendations. I appreciate this a lot. My main interest are these rare cases where anaphylaxis immediately leads to asystole (i.e. within a second of exposure), without intermediate steps such as decreasing blood pressure, tachycardia, etc.

Yours sincerely,

Rainer Spiegel

Dear Dr Spiegel, cardiac arrest or pulseless electrical activity can occur following severe anaphylaxis. But cardiac asystole immediately Following anaphylaxis is not very common common .If patient have preexisting cardiac disease like IHD, sick sinus syndrome or LV dysfunction then immediate hypotension in anaphylaxis may precipitate asytote. Other factor may be coronary vasospasm specially ofRCA or direct cardiotoxicity of drugs... Does your patient have any preexisting cardiac disease? 

Dear Dr Dan,

thank you so much for your helpful answer, this is very much appreciated, in particular the relation to Kounis syndrome.

Yours sincerely,

Rainer Spiegel

Dear Dr Majumder,

Thank you so much for your helpful advice. To answer your question whether the patient had any pre-existing heart disease: as far as I remember, he had no cardiac disease. In the end, the patient had a ROSC after approximately 10 minutes of mechanical resuscitation and administration of multiple adrenalin doses.

Yours sincerely,

Rainer Spiegel

Dear all,

Thank you again for all your excellent comments. I appreciate them a lot.

Yours sincerely,

Rainer

Dear Dr Rainer,

I would like to share with you an article on this issue (link below) -

Kounis syndrome, a disease to know: Case report and review of the literature

Sincerely,

Tatiyana