Articles, Blog

Septic shock – pathophysiology and symptoms | NCLEX-RN | Khan Academy

September 5, 2019

– Septic shock is a
very serious condition. About half the patients
who have septic shock will die within the first
month of their diagnosis. But what is septic shock? Let’s break down the two words. Septic comes from the old
Latin term meaning “rotten”, and the word shock, of course, means decreased tissue oxygenation
and low blood pressure. So combined, it’s decreased
tissue oxygenation caused by something that is rotten. Now, this rotten thing is an infection, infective material, that causes some sort of inflammation. So it’s infective material that causes decreased oxygenation of tissues. So how does infective material do that? Let’s take a look at a blood vessel and of course the blood is used to deliver oxygen to tissue. So here’s some red blood cells, and I’ll put some tissues right here. These little boxes represent cells. So these red blood cells are supposed to transfer oxygen, this
little purple substance right here, to these cells. Delivery of oxygen to the tissues. Now let’s say there’s some sort of infective material in the bloodstream. White blood cells will encounter
this infective material whether it’s bacteria,
virus, or a fungal infection, that’s in the bloodstream. So now your blood vessels are like pipes, septic pipes, containing this sewage, this unclean material. It’s no longer sterile. So this white blood cells, their job is to find this and clean it up. Of course when white blood cells encounter this infective material, they activate. When they activate,
there are several things these white blood cells do. First, they’re going to call on other white blood cells to
come and check this out, because the idea is you want to recruit as many white blood cells to wherever this infective material is
so you can eradicate it. So first, white blood cells recruit their buddies. Now here comes a major point. This infective material is normally not in the bloodstream, in fact, it’s usually out here in
the interstitial tissue. So usually white blood cells have to get into the interstitial tissue
and eliminate the threat. White blood cells do that
by releasing molecules, such as nitrous oxide. The molecules that are released interact with the blood vessels, and cause the blood vessels to do a couple things. First of all, blood vessels will dilate. Or in other words, the
diameter of the blood vessel will increase in size. So let me go ahead and erase some of this so we can show the dilation
of the blood vessel. So let’s make this dotted, showing that it was this size, and now, blood vessel diameter increases. We’ve increased from this size to a little bit larger. This causes a localized
decrease in vascular resistance, systemic vascular resistance. The blood, all of the blood
contents, have more space to move around, and there’s
less resistance that they’re bumping up
against, because of this widened diameter of the blood vessel. So there’s increased diameter of the vascular space. Of course, this makes
sense if this is happening locally, blood slows down in an area where there is an infection. Because remember, the
immune system usually encounters infective material
in the peripheral tissues. To be able to get into
the peripheral tissues, white blood cells need to
make the blood vessels leaky. So that’s the second thing
that’s happening here. Increase diameter and
increase permeability, or leakiness, of the blood vessels. Here is actually the cause of shock. You have this infective material in the blood vessels
all throughout the body, so this happens everywhere, systemic vascular
dilation, or vasodilation. This decrease in vascular
resistance causes a drop in blood pressure,
because remember, vascular resistance and cardiac output equals blood pressure. A large drop in this causes a large decrease in pressure. But also they have low tissue perfusion, because the equation for tissue perfusion is really the same,
cardiac output and systemic vascular resistance contribute
to tissue perfusion. But let me show you something else that’s causing low
oxygenation of the tissues, low tissue perfusion. You’ve got these cells that are receiving oxygen from red blood cells. With the increased leakiness, fluid will get into the tissues. So you have all this fluid buildup in the tissues, and this makes it really difficult for oxygen to get
to the cells it needs to. It has to diffuse through all this fluid. These cells become starved of oxygen. This is primarily what causes shock. There’s a third thing
that happens when these white blood cells encounter
this infective material. They want to destroy it, right? If you’ve got bacteria,
or a virus, or fungus, that’s the job of the white blood cells, to destroy this infective material. These white blood cells
release lytic enzymes and reactive oxygen species that cause damage to destroy this
pathogen, but again, this is happening everywhere. So not only do you damage the pathogens, but you’ll end up damaging
the blood vessels as well. So that’s number three. You have damage of blood vessels. Remember, this is happening everywhere, and because of that, serious
complications can occur. First of all, when blood
vessels get damaged, there are things called
coagulation factors in the blood. I’m gonna make them this
little lavender color. They’re a protein that
helps cause clotting, so when blood vessels get ruptured, you want to create a
clot to patch this up, so that blood doesn’t spill
into the extravascular space outside of the blood vessel. Again, this is happening to blood vessels everywhere in the body, I cannot emphasize that enough. So what ends up happening
is these coagulation factors end up getting used up. They’re trying to patch up
all these blood vessels, so clots are forming everywhere. Some of these clots actually break off into the bloodstream, so an
interesting thing happens. There’s coagulation that’s happening in the vascular system,
but the coagulation can’t keep up with the
breakage of blood vessels. So sooner or later, blood is spilling out of the blood vessels. This weird state of coagulation
in the blood vessels with simultaneous bleeding is called disseminated intravascular coagulation. Coagulation in the intravascular space, inside the blood vessels,
and it’s everywhere. It’s disseminated everywhere. This is a very serious complication that can be seen in septic shock. Another complication that can be seen in septic shock is ARDS, acute respiratory distress syndrome. As you know, the lungs
are highly vascularized, they have a lot of blood vessels, because they need to
be able to take oxygen from the atmosphere to
saturate blood vessels. Let’s, again, return to our
pathology of septic shock. This is happening everywhere, and the damaging enzymes and cytokines and different immune molecules end up damaging blood vessels
in the lungs as well. If you damage all of these
blood vessels in the lungs, then oxygen won’t be absorbed properly into the bloodstream. So patients with severe
septic shock end up in respiratory distress, because they can no longer pull in oxygen from the environment
into their bloodstream. So that’s acute respiratory
distress syndrome. A final point that I want to touch on is the cardiac output. Cardiac output will initially increase to try to compensate for this decreased vascular resistance, right? It makes sense that if you
increase cardiac output, it will even out the blood pressure. However, as septic shock
goes on, the heart, too, can become paralyzed and
damaged by all these molecules, these immune molecules. If left untreated long
enough, cardiac output will start to be depressed. Cardiac output will decrease. Of course, if you decrease
cardiac output instead, then blood pressure will also decrease. For symptoms, think about
a very severe infection. With a severe infection, you’ll see things such as fever, chills, and sweating. But a major symptom of
septic shock is warm skin. As these blood vessels dilate in size, as they increase in size,
this happens in all organs, and the largest organ in your
body is technically the skin. So the skin takes out a lot of the blood from the rest of the body. So initially, patients
will have very warm skin. However, as a patient
is in shock long enough, and their sympathetic nervous system tries to increase blood pressure, it’s going to clamp these vessels back
down to try to improve the resistance, the systemic
vascular resistance, and maintain blood pressure. With progression of septic shock, patients will eventually have cooler skin, and this is a bad sign,
because, obviously, it means septic shock has been occurring for a long period of time. And the clamping down
of these blood vessels doesn’t necessarily mean
that fluid can’t escape anymore, the blood vessels
are still going to be leaky from all these vasoactive
molecules that are increasing the leakiness and permeability of the blood vessel. So you’ll still have this
decreased tissue perfusion from all of this fluid that’s accumulating in the tissues. Also, you’ll see other symptoms such as respiratory distress,
altered mental status, and decreased urination. As organs get starved
from oxygen, they start to lose the functions
they normally carry out.


  • Reply brownmolasses November 25, 2014 at 5:01 pm

    Excellent explanation!

  • Reply Neha Patel December 11, 2014 at 4:43 am

    I absolutely love the way everything is explained here. 

  • Reply moch50 January 9, 2015 at 12:19 pm

    Nice detail, my textbook in visual form

  • Reply K Bui March 5, 2015 at 3:45 am

    thank you so much

  • Reply Gary Richardson March 22, 2015 at 5:14 pm

    I'm not sure I wanted to know all of that but it is what it is. Thank you it was very informative .

  • Reply TM April 4, 2015 at 7:35 am

    Exactly what I needed! 😀

  • Reply mia hayes May 5, 2015 at 9:09 am

    What an excellent video! all the important main points explained clearly within 8mins buy if I read this in a book it would have taken me 1 hour. The visual diagrams really helps to understand.

  • Reply Nimra Aslam May 9, 2015 at 5:30 pm


  • Reply Lea Reeves July 25, 2015 at 11:12 pm

    OMG just brilliant. thank you so much.

  • Reply SoshiHogosha4 August 2, 2015 at 1:47 pm

    At last I understand Septic shock! Thank you so much!!

  • Reply malirsal August 31, 2015 at 4:27 am

    Thanks a lot, I personally searched this in books and couldn't understand it as well as i did here. I was afraid probably of the "unaccuracy" of the terms, but for real all was very precise and helpful. Again, thanks a lot.

  • Reply Vanessa C September 28, 2015 at 4:27 pm

    So the your blood vessels dilate because of the nitrous oxide and other molecules released from WBC, and that's why you get hypotension in septic shock. Is that correct?

  • Reply Dee gonzalez October 21, 2015 at 3:24 am

    AMAZING!!!!! So clear and thoroughly explained!!!! Thank you!

  • Reply Suprateeka T November 22, 2015 at 2:13 pm


  • Reply Brad Jones December 18, 2015 at 1:32 pm

    Didn't mention the lactic acid buildup in the cells due to anaerobic metabolism…

  • Reply shaza AA December 22, 2015 at 7:25 pm

    Thank you , good explaining ??

  • Reply Abood Albouq December 25, 2015 at 10:57 pm

    Thank you very much 🙂 … i will never forget the meaning of septic shock after this diagram

  • Reply Mi The Y December 30, 2015 at 9:59 am

    What about the causative agent and its mechanism in causing septic shock, like the LPS ,gram -ive bacteria and All that things?

  • Reply ale January 1, 2016 at 9:21 pm

    The nitrous oxide cause the vasodilation? But what about the prostaglandines, and other inflamatory factors that increase the vascular permeability?

  • Reply Anita Contarini January 5, 2016 at 7:10 pm


  • Reply Ashley Balitaan January 18, 2016 at 4:03 am

    NITRIC oxide causes vasodilation

  • Reply Raul Rodriguez March 8, 2016 at 9:06 pm

    Good explanation!!!! I already understood some mechanisms related to septic shock. Thanks so much

  • Reply Reem Hussain March 14, 2016 at 7:26 am

    the best explanation ever! u are really talented , thank u so much

  • Reply anderw andrew March 18, 2016 at 2:49 am

    Metabolic Theory of Septic Shock
    Please do a search for the above
    Core tip: For decades septic shock has been attributed to an over-active immune response. However, immune modulation has failed to reduce mortality, casting doubt on a direct causal role for the immune response in the development of septic shock. A closer look suggests that septic shock is the result of a generalized build-up of hydrogen peroxide, a toxic cellular by-product generated as a consequence of the hypermetabolic state that accompanies a systemic immune response. This finding points to the systemic accumulation of hydrogen peroxide as a significant risk factor for the development of septic and non-septic shock syndromes.

  • Reply Ali Kulz May 18, 2016 at 10:21 am

    I have my shock exam next week. This is the resource that summarises all text books I have read

  • Reply Gerry Winters May 24, 2016 at 4:49 pm

    I had 2 prostate  surgeries 4 months ago followed by Septic Shock 8 days later.  One day my wife found me on the kitchen floor.  The surgeries were a Sunday picnic compared to Septic Shock.  It was a hell I hope I  never see again. I still measure my blood oxygen and pulse per minute, and blood pressure 3 times a day.  I consider myself a pretty tough guy but I  still cry every day  and I cant control it. I cried in the hospital several times a day every day. A nurse would walk in and say Good Morning and I would cry.

  • Reply Kayalvizhi Duraisamy June 8, 2016 at 5:13 pm

    Isnt there any role played by Endotoxins and its formation of a complex with LBP?

  • Reply Burnin Sage July 17, 2016 at 4:29 pm

    Great job! Thank You !!!

  • Reply agmuhammad August 9, 2016 at 11:37 am

    Just brilliant preview and explanation .
    you should add that Many Metastatic cancer Cells in the blood stream could cause a fast sever SEPSIS , and eventually death !
    it usually happens at the advanced stages of cancer or with some aggressive cancers like Pancreas CA or , Biliary CA.

  • Reply tere williams September 11, 2016 at 5:56 pm

    Please understand decreased tissue oxygenation.. Time is of the essence when dealing on this level..  Be aware and move on it please.  Better safe than sorry.  White blood cells must get into interstitial tissue to fight this internal war.  These are All great info for all to know.  Systematic vascular resistance with this particular situation and more.

  • Reply Mandana Mashoof November 13, 2016 at 11:13 pm

    Thank you so much. You explained this great.

  • Reply MADDER November 16, 2016 at 3:36 pm

    Rest in piece Muhammad Ali.

  • Reply petr petrich November 30, 2016 at 6:10 pm

    Please tell me why do WBCs release lytic sybstances in the blood stream itself when trying to damage pathogen? Why don't they phagocytose them to lyse them safely without damaging outer tissues? Thank you!

  • Reply first class roadman December 13, 2016 at 6:29 pm

    great video extremely helpful.i have an alternative explanation would like to confirm with you or anyone else is welcome .if CO=HRxSV and SV is affected by peripheral vascular resistance ( PVR), NO causes dilation decreasing PVR decreasing venous return also taking into consideration increased vascular permeability .could SV be reduced?resulting in tachycardia to maintain CO?is that not a symptom worth mentioning or does it fall vaguely under RDS related symptoms ? but once again great video ,i have just subscribed!

  • Reply khald elsherbiny January 3, 2017 at 8:23 pm

    very good

  • Reply Nooruddin Quadri January 12, 2017 at 10:21 am

    explain the two types of septic shock…..warm and hyperdynamic.

  • Reply Nifty Dude January 22, 2017 at 7:04 pm

    I just got septic shock recently due to pneumonia and it was hell. my mom is a nurse so she was able to send me to the hospital and caught the septic shock very early on. I was only in the ICU a week but it was terrible. I'm 15 and never had an experience quite so insane ever before, and I would never wish an experience like this on anyone ever.

  • Reply Luke Fenech February 3, 2017 at 2:33 am

    This is the best explanation of sepsis I have found so far. Thank you very much.

  • Reply Ernest Whilhem February 13, 2017 at 2:08 am

    This video should be used by kindergarten kids, not medical students. Basic "information" with many errors. Thanks for wasting my time.

  • Reply FrankieBeans February 27, 2017 at 11:23 am

    my father just had a distributive shock 2 days ago they are saying it could possibly be septic I just listened to the first couple seconds of the video and my heart just dropped.

    the doctor said they may possibly be bacteria on one of the lines of the pacemaker he has on his heart .

  • Reply Kamran Boka March 7, 2017 at 9:55 pm

    Correction: @2:19 "nitric" oxide not nitrous oxide. Great video!

  • Reply Lauren Stewart March 25, 2017 at 5:50 pm


  • Reply Mr Nullius Testikleez Eeasteez April 3, 2017 at 11:58 am

    This, I reckon, is the best video on septic shock I've ever seen.

  • Reply Samuel Chase Shoptaw April 11, 2017 at 7:44 pm


  • Reply Jenna White April 19, 2017 at 12:28 am

    You're the best!! Your videos make it SO much clearer. You're an excellent teacher. Thank you so much for taking the time to make and post these. 🙂

  • Reply Courtney Tewary April 25, 2017 at 2:43 am

    THANK YOU!!!

  • Reply kevykev913 June 16, 2017 at 5:47 pm

    interesting even for the layman

  • Reply Nesrine Saoudi June 26, 2017 at 4:48 pm

    WHAT A NICE JOB ! thank you

  • Reply Allison Wayman July 11, 2017 at 9:53 pm

    oh my God this exactly what happened to my husband that resulted in his death with in 2 weeks of being diagnosed.

  • Reply K Jugs July 30, 2017 at 10:56 pm

    Wait I have a question. So technically when you have blood infection, WBCs are useless and would even cause your death? I had a blood infection once from UTI, had a 3-day fever but then it settled down after I took localized antibiotics. But the doctor said those antibiotics I took are for my kidneys; wonder how it 'cured' the infection in my blood.

  • Reply Amber Shaw August 10, 2017 at 6:32 pm

    This is brilliant thank you. Just helped me really understand septic shock in time for my OSCE!

  • Reply Luke Histon September 7, 2017 at 7:58 pm

    Muhammad Ali died from this

  • Reply Rob Kranz September 27, 2017 at 9:46 pm

    Go Kahn

  • Reply LETMEC4FREE October 31, 2017 at 7:41 am

    This is dynamite, thank you!!!!

  • Reply Benjamin Washington November 13, 2017 at 7:44 pm

    Awesome video!

  • Reply udaya udaya ranasinghe seneviratne December 24, 2017 at 9:42 am

    I. Would.

  • Reply Helena Halasz January 6, 2018 at 10:39 am

    Thanks for the awesome videos! Quick ques: you said that the WBC release NO? I thought the endothelial cells are the ones that would release nitric oxide, thus causing the vasodilation? (Also, maybe if you could discuss the role of LPS in a future video, that would be great 🙂 )

  • Reply life is crazy February 3, 2018 at 4:19 pm

    best video…. excellent explanation….really got to know the importance of the topic

  • Reply Siva Mahalingam February 14, 2018 at 10:14 pm

    Fantastic video,

  • Reply Yousaf Shaikh February 15, 2018 at 12:31 pm

    Why is the effective material in the interstitial fluid"

  • Reply Khamis Zananiri February 26, 2018 at 6:21 pm

    excellent.thanks sir

  • Reply Agata Ramesh March 5, 2018 at 12:27 am

    I thought nitrous oxide was a laughing gas. is he maybe  meaning nitric oxide

  • Reply jocy galvan March 12, 2018 at 8:32 pm

    omg you totally saved my ass on my homework in nursing school plus i actually understood the process where as reading two pathophysiology books i couldnt understand it well enough so thank you somuch what would i do without youtube?

  • Reply Dr Balram Ji Omar March 16, 2018 at 2:07 am

    wonderfully explained

  • Reply Susan Golian April 13, 2018 at 6:04 am

    This is a splendidly informative video. Thank you SO much!

  • Reply General Larsson April 24, 2018 at 6:06 am

    Thank you for this video!
    I have had septis chock, and this was very helpfull To understand it

  • Reply Channell 110 May 2, 2018 at 4:50 pm

    Good presentation but there is always a problem of low voice in videos please solve this problem in the next videos

  • Reply ivan susilla May 25, 2018 at 7:27 am

    Do you think tramadol and temazepam had something to do with sepsis?

  • Reply Sam Hussein May 28, 2018 at 3:39 pm

    Perfect ??

  • Reply iliketoreid June 13, 2018 at 12:25 am

    This video helped me so much to understand septic shock! Thank you! I always watch it when I need a review! I recommend it to anyone who is struggling to understand the topic!

  • Reply Nout ayyash June 14, 2018 at 9:51 am

    everything is clear about sepsis in less than 10 min vid! thank you.

  • Reply Nick Webster August 6, 2018 at 1:32 pm

    This video was extremely informative, well explained, and very helpful!

  • Reply Lindsey Atkins September 11, 2018 at 5:45 pm

    This is happening to me over and over and it has damged so much of my tissues all over and lost alot of tissue everywhere. And no one believes me . I'm very sick and on fire and feel severely dried out and my skin is peeling off, my tissues swelled for so long and turned cold and clammy and fluid would start leaking out of my skin I cant breath and my head feels like Iv been drinking no one is listening and im fighting for my life

  • Reply BRIAN FLORES ARMENDARIZ September 17, 2018 at 1:25 am


  • Reply Erebus S September 30, 2018 at 8:39 pm

    Clear and precise explanation indeed. Thanks much for sharing your knowledge.

  • Reply MrGoblin60 October 14, 2018 at 9:01 am

    Thanks Doc. This is so eloquently yet simply articulated. Excellent presentation.

  • Reply Alonso Iriarte Wachtendorff November 10, 2018 at 9:30 pm

    Finally understood, your explaining is so comprehensive

  • Reply Caiyll November 13, 2018 at 1:50 am

    My grandpa is fighting septic shock right now. His kidney and liver has failed already. Septic Shock is no joke.

  • Reply Cr33p November 15, 2018 at 6:06 am

    Oh god I just listened to this and now I just wanna die. What a horrific way to die.

  • Reply Merida Dream November 17, 2018 at 8:58 pm

    Thank uuuuu ☺️??

  • Reply Bianca Rojas November 24, 2018 at 2:33 pm

    Te amo. Me salvaste la vida ❤️??

  • Reply lock dot 2 December 6, 2018 at 5:13 am

    I thought it was not searese i have it i was diagnosis yesterday im scard now

  • Reply Ohnolillam December 7, 2018 at 1:06 am

    So good!! Thanks!!

  • Reply Mikhaeel December 16, 2018 at 7:50 pm

    Great teaching like this makes me eager to learn more 🙂 thank you!

  • Reply Pulathisi Senevirathne January 1, 2019 at 8:59 am

    My mom died of Sepsis last week ?

  • Reply Claire Murphy January 25, 2019 at 10:33 am

    This subject is really confusing me I have a question I need to answer but getting confused with immune response and inflammatory response… with regard to sepsis what happens at the immune response level and then the inflammatory level?

  • Reply PostalBound February 11, 2019 at 8:17 am

    As someone who is recovering from Septic Shock, I can't tell you how much I appreciate this video. This is by far the best explanation. Thank You !

  • Reply Elise Calabretta February 11, 2019 at 8:59 pm

    Would you have a LOW WBC count in late stage sepsis due to the WBC being in the interstitial space treating the infection?

  • Reply kabtastick February 12, 2019 at 7:28 pm

    Explained simply, but a bit too simple for me. It sounds patronising the way you explain details.

  • Reply Santa Jacky March 19, 2019 at 12:19 am

    a buddy of mine died from this in 2019 by the operation he had on his balls with a wound vac

  • Reply Casper Christiansen April 1, 2019 at 1:25 pm

    So histamine doesn’t cause the inflammation?

  • Reply Aeroll Dela Cerna May 1, 2019 at 7:07 am

    how pneumonia causes septic shock?

  • Reply JIGANGA NYOROBI May 29, 2019 at 7:24 pm

    excellent,simple and clear
    thanks much

  • Reply Vinoli Kavin July 8, 2019 at 12:43 pm

    Thank you so much ?

  • Reply Eddie Sims July 25, 2019 at 6:54 pm

    excellent explanation, after reading med surge Book and watching this video it all makes sense!

  • Reply Irish Rock August 5, 2019 at 4:17 am

    Great video,

  • Reply Agman Trivedi August 13, 2019 at 7:52 am

    That means the body is so hell bent on "curing" you that it actually kills you – Too much of love!

  • Leave a Reply