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Sepsis: Systemic inflammatory response syndrome (SIRS) to multiple organ dysfunction syndrome (MODS)

Created by Ian Mannarino.

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  • orange juice squid orange style avatar for user Abraham George
    What is ischemia? He used it in multiple areas of the video.
    (5 votes)
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    • piceratops seedling style avatar for user Terra Fasold
      As Gábor said, it is when a certain tissue area is blocked from receiving blood supply, effectively cutting it off from receiving not only oxygen, but glucose and other nutrients from the blood necessary to sustain the tissue area. The severity of the damage will depend on what type of tissue is affected (tissues that are more active obviously require more nutrients, and the kidneys are extremely dependent on blood flow, receiving ~20% of blood flow per cycle) and how long the blockage lasts. Hope that helps!
      (4 votes)
  • spunky sam blue style avatar for user Vann Renthel
    Hi! I study to be an intensive care nurse in Norway. We now learn to use the sepsis 3 score SOFA, and that the SIRS criteria is on it`s way out... Are you hinking of changing the lesson a little bit? Than you for a lot of good teaching in the academy!
    Best regards, Hannah
    (5 votes)
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  • blobby green style avatar for user Touch.the.sky93
    Isn't the definition of sepsis SIRS + a confirmed SOURCE of infection, i.e. investigations that indicate positive results such as a positive blood or urine culture etc.?
    (2 votes)
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    • female robot amelia style avatar for user sue.peck.wetzel
      It can be either confirmed or suspected source of infection. i.e. someone with high RR, high HR, high WBC with SOB and a CXR suggestive of infiltrates. Although not confirmed with cultures, if it is highly suspicious it is considered sepsis. If there is an increased need for oxygen, renal dysfunction (as seen with increased BUN and creatinine), or change of mental status (dysfunction of the brain); then that would be considered severe sepsis.
      (1 vote)
  • blobby green style avatar for user abescasa07
    what are your sources for information?
    sometimes I find discrepancies in what khan academy provides versus what I find in my textbooks or school/work modules and I want to make sure I'm not getting misinformation but really enjoy khan videos!
    let me know, thanks!
    (1 vote)
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  • female robot grace style avatar for user Anna
    RR is normally between 12 and 20 Breaths per minute unless you have an unusually low heart rate or an unusually fast heart rate. Normal heart rate in a non-athlete is between 60 and 100 BPM unless it is young or old. In an athlete though it can be as low as 40 BPM without any symptoms because of higher stroke volume and blood pressure leading to slower heart rate and that being caused by increased cardiac muscle or in medical terms, hypertrophy.

    So why is the tachycardia in the sepsis spectrum considered to be above 90 BPM? Wouldn't it be better if it were considered to be above 100 BPM like all other tachycardia?

    Also wouldn't a lower heart rate lead to higher likeliness of an infection in the blood stream which would lead to higher likeliness of things like MODS because of how there is more time for the infectious agents to get into the blood since the whole immune system is moving slower?
    (0 votes)
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    • female robot amelia style avatar for user sue.peck.wetzel
      Although a heart rate above 90 is not considered tachycardic, it should be on the radar if someone is having some sort of inflammatory response. Also, to note, if someone is on medication to lower the heart rate (such as a beta blocker or calcium channel blocker), you don't necessarily see any rise in heart rate at all in sepsis. The heart rate is just a clue that the body is trying to compensate and keep cardiac output high enough for tissue perfusion. A lower heart rate in the setting of shock is usually either a sign of neurogenic shock as the brain swells, from severe hypoxia, or right before death. A slow heart rate doesn't necessarily increase the risk for infection to cross into the blood.
      (1 vote)

Video transcript

- [Voiceover] When you hear the term sepsis or septic, you might be thinking of sewage. In fact, that's what comes to my mind, septic tank. And it's not so much that you have sewage in the body, it's more that you have an infection or something that causes inflammation in the bloodstream. Your blood is normally clean and doesn't have any infective material in it, but in septic shock, that's kind of the issue. That's what causes septic shock. Septic shock is, shock, decreased tissue perfusion, decreased oxygenation of the tissues, and low blood pressure, hypotension, which is caused by some sort of infection or inflammation. Now, septic shock is really part of a greater category known as sepsis, and I'm going to have to get into some nitty gritty detail here, so you can understood the categorization of septic shock. Sepsis is really just a spectrum. You start with more mild symptoms, and you progress to more severe symptoms, and at the more severe end of the spectrum is septic shock. So, let's go ahead and start it out. The first category that fits into this sepsis picture is known as SIRS, and that stands for Systemic Inflammatory Response Syndrome. Now, the name of that itself, Systemic Inflammatory Response, suggests that this is in response to something that's inflammatory. Duh, it's in the name, inflammatory response, but it does not necessarily mean that there's an infection. To meet SIRS criteria, a patient must satisfy two or more of the four following signs or symptoms. First of all, having a temperature above 38 degrees Celsius, so that's 100.5 degrees Fahrenheit, or having a temperature less than 36 degrees Celsius, which is 96.8 degrees Fahrenheit. Now, to give you an idea of what's normal, normal body temperature is 37 degrees Celsius or 98.7 degrees Fahrenheit, so this is about what a patient will have if they have a normal temperature. So, being very feverish, or being very cold and clammy, can be a part of SIRS criteria. The next criteria is a heart rate above 90. Now, notice, normally when you think of a rapid heart rate, Tachycardia, which is a fast heartbeat, that's said to be above 100, but for SIRS criteria, it only has to be above 90. Next, respiratory rate is above 20, or the PaCO2, the partial pressure of carbon dioxide in the body, is less than 32. So, either one of these will satisfy one criteria. So, so far we have temperature, heart rate and respiratory rate, rapid breathing, as three criteria of SIRS, Systemic Inflammatory Response Syndrome. Now, really quickly, PaCO2 is normally 40. Less than 32 is because you're breathing rapidly, so you're expelling off carbon dioxide, and, of course, a normal respiratory rate is around 12 to 15. The final criteria of SIRS is white blood cells, and if you have greater than 12,000, or less than 4,000, then this meets SIRS criteria. Think of it this way, either your body is responding appropriately and ramping up the amount of white blood cells, immune cells in the body, or, more dangerous, whatever infective material, such as, maybe bacteria or virus in your body, is winning the battle, and their are less white blood cells available. Also, if you see greater than 10 percent band cells, that can fulfill the criterion, also. Band cells are just young, immune white blood cells, so the idea is you have a lot of white blood cells that need to be produced rapidly, so the body is trying to create white blood cells quickly, but instead, all it has is these young, immature band cells, and so it releases them, because, better to have something to be able to fight this war against this infection that's going on in the blood. Now, remember, these are just really merely clinical clues that could suggest widespread inflammation. I mean, if you go for a jog, or go for a run, you already fulfill two of these four criteria, right? You'll have your heart rate up and your respiratory rate up, as well. So, really keep it in mind, keep the clinical picture in mind when you're thinking of SIRS criteria. Next on this spectrum is the category sepsis. So, sepsis is just SIRS, the Systemic Inflammatory Response Syndrome, with a confirmed infection. And sepsis is considered more severe if a patient is showing symptoms of organ problems, organ damage or organ dysfunction. So, for example, a patient who's breathing rapidly, having difficulty breathing could have damaged lung tissue, or a patient with severe abdominal pain might have a bowel perforation, or intestinal issues. Or, maybe a patient is having a low urine output. That shows damage to the kidney. So, looking out for organ damage is how you would determine the severity of sepsis. Septic shock is the next step, it's sepsis, plus hypotension that just does not go away. And, what I mean by it does not go away, I mean the health practitioner is giving fluids, and the hypotension's still is not going away. And I want to make a point here. Adequate fluid repletion is 30 milliliters per kilogram. So, you take the patient's weight into account. So, for example, a patient who weighs 50 kilograms you would give 1500 milliliters as quickly as possible. And if the blood pressure does not go up with this fluid challenge, then the patient is in shock. Last of all, on the most severe end of sepsis, of the sepsis spectrum, is MODS. This stands for Multiple Organ Dysfunction Syndrome. Multiple Organ Dysfunction Syndrome is when a patient has severe septic shock with organ failure. Now, I know that I said at the more severe end of sepsis, I said there would be organ dysfunction. You'd have difficulty breathing, gastrointestinal ischemia, decreased oxygenation of the intestines, causing GI perforations, and maybe kidney damage, as well, causing decreased urination. But, a lot of times in severe sepsis, this organ dysfunction can be recovered. In MODS, it's essentially beyond the state of being able to recover. And, also in Multi Organ Dysfunction Syndrome, the liver begins to fail, and if the liver begins to fail, it cannot clear out the toxins that the body has. So, the infective material, the bacteria or whatever infection is in the blood, can no longer be cleared out effectively by the liver, and the body just completely shuts down. And so, with sepsis, you want to catch it as early as possible so that it does not progress to more severe septic shock or Multi Organ Dysfunction Syndrome, when all the organs begin to shut down.