What is anaphylactic shock? Anaphylactic shock is when the body has an allergic reaction and there is a sudden drop in blood pressure, and the airway constricts. Unless treated, it can be fatal.
Anaphylactic shock is at the very far end of an allergic reaction. The body goes out of control, and the results can be fatal. Anaphylaxis is not that common, but it can be fatal, so everyone should be aware of it. Some people are not allergic to anything, and people that do have allergies can have a wide range of effects from very mild to very severe. Anaphylactic shock is on the very severe end.
When we have an allergic reaction to something, our body is mistakenly reacting to the substance as though it is a threat. Our immune system works by neutralizing threats as quickly as it can. To do this, it keeps a library of all the invaders it has encountered so that it can respond more quickly the next time one comes. However, sometimes the immune system can get things wrong. When the body comes into contact with one of these allergens, such as pollen, peptides are released. Peptides are very small chains of proteins, and they trigger B-cells to produce IgE antibodies. The IgE antibodies spread out through the body, and they mark all of the “invading” cells so that they can be picked up by the body’s immune system. The IgE antibodies attach to receptors in mast cells, which are a type of immune cell, and the mast cells produce histamine and several other chemicals. Histamine and these other chemicals are the body’s first line of defense against invaders, but one of the biggest problems with an allergic reaction. Histamine is a chemical that has lots of jobs in the body. When it comes to the immune system, its job is to signal cells to begin the inflammatory process.
With inflammation, blood vessels are dilated so that plasma can flow out of them into the surrounding tissue. This causes the tissue to expand, which is inflammation. White blood cells can enter the tissue through the plasma to attack the invading particles. Once they have killed them, the invaders are flushed out through the plasma as well. This is all well and good if your body has actually been invaded by something like a virus, but not so good if it is just pollen or peanuts. The inflammation causes swelling, and the dilated blood vessels cause rashes and itchy skin. Extra fluid causes runny noses and coughs as well. The reaction usually passes after a while, but sometimes it can get even worse and become anaphylaxis.
The histamine triggers the inflammation, but the tissue around the lungs and up through the throat also expands, narrowing down the airway. The blood vessels over dilate and too much fluid comes out of them, causing blood pressure to drop. This means the heart has to beat faster, and there is less blood getting to the brain and other organs. The skin can also become very red and itchy. The immune response causes other problems as well, but these are the main ones. If these symptoms are not treated, they can gradually get worse and lead to death. Death would come from asphyxiation because the person cannot get enough oxygen in through their constricted throat. Or it can come from multi-organ failure and cardiac arrest because the blood pressure drops so low that the heart can’t cope.
That being said, these days, anaphylactic shock is rarely fatal. This is because most people who know that they have a severe allergy carry an EpiPen, and most people are not that far from a hospital. An EpiPen contains a dose of epinephrine, which is injected into the thigh muscle. It gets into the bloodstream very quickly this way and goes to work straight away. Epinephrine is adrenaline, and it works on anaphylaxis by constricting the blood vessels, which straight away reduces inflammation. It can also block the chemicals that are causing the allergic reaction. Often, one shot from an EpiPen is enough, but sometimes two shots are needed. The person should then go to a hospital. If the EpiPen doesn’t work, once the person is in the hospital, they will be treated with adrenaline, but they will also receive IV fluids, which will bring the blood pressure back up to normal. If things progress that far, the patient can also be intubated so that they can breathe.
Unfortunately, the patent for EpiPens is held solely by the drug company Mylan, which has no interest in reducing its price. The shot of epinephrine in an EpiPen costs about $1, while the EpiPen itself costs about $600 (in the US). I understand that they need to make back their research money, but that does seem a trifle over priced. And this is what I learned today.
Sources
https://my.clevelandclinic.org/health/diseases/8619-anaphylaxis
https://en.wikipedia.org/wiki/Anaphylaxis
https://medlineplus.gov/medlineplus-videos/histamine-the-stuff-allergies-are-made-of
https://www.mayoclinic.org/diseases-conditions/anaphylaxis/diagnosis-treatment/drc-20351474
https://www.beckerentandallergy.com/blog/epinephrine-for-anaphylaxis
https://www.health.harvard.edu/blog/way-lower-cost-epipens-2016101210460
image By Tokyogirl79 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=50838162