Anaphylactic shock | Circulatory System and Disease | NCLEX-RN | Khan Academy


– [Voiceover] Anaphylactic
Shock is probably one of the shocks that most
people are familiar with. It’s also known as anaphylaxis. Anaphylactic shock is an allergic reaction that’s severe enough to cause shock. And of course shock is
decreased tissue perfusion, or in other words decreased
oxygenation of tissues. There are a number of different things that can cause an allergic reaction. For example, bee stings can
cause an allergic reaction, peanut allergies, food allergies, pollen can cause allergic reactions and so can certain medications as well. Now of course, allergies
can be either very mild and seasonal such as hay fever and sometimes allergies can be so severe that it can cause shock. But how does it cause shock? Well first of all to answer that, I want to acknowledge that there are two types of anaphylaxis. Those that are immunologic and those that are non-immunologic. And I’ll go ahead and start
with immunologic anaphylaxis, because that’s actually
the most common type. In immunologic anaphylaxis,
there’s some sort of allergic agent, whether
it’s poison from a bee sting or a food allergy that
somehow gets in to the system. And whatever this material is, it’s known as an allergen because it generates an allergic response. So when this allergen
first gets into the body, it will interact with B cells, and not B cells like the
insect, the bee right up here, but B cells as in the letter B. Now these cells are the
antibody creating cells of the immune system,
they create antibodies. And antibodies are essentially
a little Y shaped protein that is used like a signal marker to find something that’s
foreign, foreign material. So in this case, the antibodies will be reacting to the allergen. Now antibodies that are created
in response to an allergen, are known as IgE. IgE stands for immunoglobulin E. Globulin means protein and
immuno just means immune. So really it’s immune protein
and the classification is E. Now the reason I want to emphasis this, is because IgE specifically
docks on to other immune cells which are known as Mast Cells, and these mast cells are
mediators of the immune system. So what ends up happening
is, once IgE is created, it will dock on to these mast cells. So this all occurs when a person is first exposed to an allergen, and this is called sensitization. The immune system is
sensitized to this allergen. So the next time that
this allergen comes along, it will create a rapid, allergic response. The allergen will dock
on to these antibodies and when they do, the mast cells activate. And when mast cells activate,
two main things happen. First of all, mast cells
release immune molecules known as cytokines. Cytokines are essentially used
for cellular communication. So mast cells communicate
with other white blood cells and tell them to come over. So what ends up happening
is these white blood cells continue to recruit
more white blood cells, and it’s a cycle that creates more and more white blood cells being recruited and activated in response
to these allergens. Now that activation of both the mast cells and the immune cells, causes release of another molecule known as histamine. Now histamine is a potent vasodilator. In other words, it dilates blood vessels. So here, with the dotted line, I’m showing a blood vessel size
before and after histamine, the diameter of the
blood vessel increases. Now this is happening in the blood stream in the entire body, and it causes a large drop in blood pressure. So patients lose the function
of their circulatory system and are no longer able
to distribute oxygen and so that’s how an allergy causes shock. And also, let me note that
histamine causes blood vessels to become leaky, so fluid
escapes the vascular space which causes swelling to
occur all throughout the body. So a patient has massive swelling along with a massive
drop of blood pressure. Now the second type of anaphylaxis is called non-immunologic. Now non-immunologic anaphylactic shock is essentially the same
as immunologic shock, it’s just the pathology
is slightly different. Instead of mast cells
being stimulated by IgE, the allergen specifically targets the receptors on the mast cells. And so you get the same process of histamine release as
well as cytokine release, which of course causes the
super immunological response as more white blood cells are recruited and then also causes this
drop of blood pressure. So what are the symptoms that
we see in anaphylactic shock? Well the symptoms are
going to be characterized by the actions of histamine. So a patient with anaphylactic shock has this major drop in blood pressure due to vessel dilation. So we’ll see flushing of the skin, as blood vessels dilate and blood starts to saturate in the skin. And swelling as fluid is getting outside of the blood vessels. And itchiness, which is also
caused by histamine release. So these are all symptoms that you would come to expect from an immune response. You may see other various symptoms such as rhinorrhea, which is a runny nose and this is caused by vessel dilation in the nasal vasculature, so you have an overactive
release of fluid. But the symptom that I
really want to get to, occurs with the lungs. Histamine not only causes vessel dilation, one of it’s most serious
symptoms is bronchospasms. Spasms of the bronchi,
the main air passages to the right and left lungs. So these bronchospasms make it difficult for a patient to breath. What makes it worse also is that swelling can be occuring in the throat as well, which can close off the airway, making it even more difficult to breath. So a patient comes in
whose non-responsive, he’s not breathing, and
you check and find that the patient has a very low blood pressure. So what do you do? Do you order lab tests? No, that’s a terrible idea. This patient is having
a severe bout of shock. It should already be apparent based off of the clinical symptoms
that this patient has. Especially the low blood pressure, severe low blood pressure should indicate that right away, something
needs to be done. So you progress right to treatment. And treatment is based off of the ABC’s, airway, breathing and circulation. So number one, you want
to establish the airway. If a patient is not breathing, you want to give them 100% oxygen so you can fill up their lungs. And ventilating the
patient with a bag mask, to push air into the lungs,
may be one of the first ways to respond to a patient
who has anaphylactic shock. Along with this, the blood
pressure needs to be maintained. And there’s one medication
that’s especially effective at maintaining blood pressure in patient’s with anaphylactic shock
and that’s epinephrine. First of all, of course patients have these very dilated blood vessels. Now epinephrine has strong
sympathetic activity, so it acts in a way to constrict
blood vessels back down to maintain blood pressure. So this directly counteracts
what histamine does to blood vessels. Epinephrine also effects the lungs and causes bronchodilation,
so it opens up the airways. So this is important to allow
airflow back into the lungs. Now to also maintain blood pressure, IV fluids will help fill
up the vascular space. So these are the main ways to treat a patient with anaphylaxis. And along with this, you
can give antihistamines to really directly counteract the effects of histamine in the body. But of course, let me emphasize that epinephrine and IV fluids are the mainstay of treatment, because they act to immediately reverse the low blood pressure and restore a patient’s circulatory system.

43 thoughts on “Anaphylactic shock | Circulatory System and Disease | NCLEX-RN | Khan Academy

  • Can you guys at khan academy make videos starting from base on because im in eighth grade and they currently dont teach biology at school so i study it on my own i do this because i want to become a surgeon. I currently volunteer at a hospital 4 times a week so i feel that if you started from the beginning that would really help

  • It's horrible. I was actually in anaphylactic shock. It happened so fast I couldn't believe it. I was barely moving air by the time paramedics arrived and in the ambulance I stopped breathing altogether. I thought his face was going to be the last thing I saw.

  • As I got older my tree nut allergies seemed to evolve from slight trouble breathing and puking to no trouble breathing and instead agonizing pain all throughout my entire body to the point where epinephrine injections have no effect. A lot of people can grow out of allergies as they grow older, but I was triggered multiple times, either through accident or on purpose due to some giant asshole who thought it would be a good idea to murder me. Though I wonder what the difference between peanuts and tree nuts are, because I can eat peanuts just fine.

  • thank you for sharing that…..its happened twice to me, one in a very serious car crash and an allergic reaction to what my dentist numbed me with

  • From what I see on other videos it seems that Anaphylaxis is autoimmune disease when It revolves around Certain foods such as apples,honey,etc. I want to know does the drugs that suppress the immune system can battle the Anaphylaxis?

  • the way i see it if i had too choose between ventilating the patione with CPAP or BiPAP and giving them epinephrine i would reach for the epi pen first as that is also a treatment for maintaining the airway due to smooth muscle dilation, then pop them on ventilaion

  • Recently had a miraculous reverse total shoulder replacement. However, immediately after getting home I took my first prescribed DOXYCYCLINE!  SUDDENLY MY WIFE, DAUGHTER AND, NEIGHBOR WERE HOVERING OVER ME, HOLLERING, YELLING… With record speed, another group of people hovered over me and, I soon was on my way to an ambulance. One of these people asked me a bunch of questions and, I was able to reply. Apx 2 miles later I was in the local hospital's emergency room! ** Most of my story was learned thru my wife & daughter. They nor, I remember the word ((anaphylactic shock)) being mentioned but, my wife (was) told at the ER I  was there because of an  (adverse reaction to DOXYCYCLINE)!  ** I was admitted to the local hospital for 3 days, had much difficulty sleeping and, after what seemed like a bad; very fitful nightmare , I was finally allowed to go home!   Due to osteo-arthritis, my other shoulder will also have to go thru a miraculous total reverse replacement. ** I always say a prayer before I go under, me the doctor but, I have told my story to allI am happy with my shoulder and, will do it again. I do not blame to doctor. It's also important to tell what I was told by my loved ones who I credit for saving my life with (pumping my chest, moving my protruding tongue out of the way and calling the ambulance, ***Just before going home from the local hospital, I asked a heart doctor, "You mean to tell me, after all the tests, you guys say my heart is fine? He told me, "There is absolutely nothing wrong with your heart, Joe".  WHAT IN THE WORLD HAPPENED TO ME?? ANY IDEAS?Thanks for your post.

  • These are very helpful, I just have one question. I thought the Leukotrines caused bronchoconstriction, is this incorrect?

  • Thank you so much I was taking penicillin and then my legs became string beans and I went down fast. Luckily I had only taken part of the pill for some reason . I had taken penicillin before in the past and thought nothing of it.  I started to pass out. My friend came into the room just then and I couldn't hear him and everything started to turn black
    and his face was a little circle. I laid there a while and then could hear and could see again. And waited till the paramedics came and took me to the hospital.

  • I am a paramedic student and you just solidified my understanding of anaphylaxsis. Thank you so much. I was also confused about what actually happened, even after I got my EMT. THANK YOU!!

  • I had this and I found out I am allergic to chocolate 🍫 that’s what my family doctor told me he said I had anaphylaxis reaction. At first I didn’t know what it was now I know. My reaction only lasted for like 5 or 7 minutes.

  • As usual, you of Khan Academy make everything so clear and easy to understand. It was funny to know at 33 which mechanism almost killed me for four times. Thanks.

  • does epinephrine stop the leakiness of blood vessels??
    i mean what should we give for leakiness ..
    plzz plzzzz reply

  • A peanut sat on a railway track
    It’s heart was all a’flutter
    A train came speeding
    Down the track
    TOOT TOOT

    Peanut Butter

  • RN and my first sting was while at work. I iced the sting area and took 50 mg PO banadryl asap. I experienced an internal warm feeling much like IVP contrast die administration internal warmth. I became flushed- bright red like I had an instant sun burn on my face chest and back. I could feel my hear pounding inside my head and extremities. Head pounding like a hard physical workout. Increased pressure in my ears like on a flight. My HR 140 – 160 BPM. My BP went up instead of down. I went unconscious. I have GI symptoms later. I have tried immunotherapy and rebounded several times early into the treatment. It took over four rounds of epinephrine. I was stung again twice at one time and I continued to rebound numerous times. I have vocal cord damage now and I am treated as if I have a mast cell disorder. I pray that I can be seen at mayo clinic one day. I would have never survived if I were not a nurse. Few doctors know anything about how to keep me alive with the next sting. ( Please use Epi first. The urgent care and ED tried benadryl and steroids only and it sent me into endless rebounds. The pain of the rebounding anaphylactic reactions is unbearable)

  • Once the body have been introduced to an allergen once, does the IgE for that allergen remain attached to mast cells? Or is it re released by memory B cells upon second exposure?

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