Hemodynamics question - page 2

I'm a student, of course, and here goes... (thanks to the smart nurse who helps) Why is afterload increased in cardiogenic shock? I understand the preload, but If blood volume is increased in... Read More

  1. by   papawjohn
    Hey Nurse032006

    Oh MY God....this ancient ghost rises out of the wishing well---makes me play an air-guitar to a GordonLightfoot tune....

    Well, you have to think....

    Cardiogenic shock is because the 'heart is in shock', OK? So what are the numbers from the PA Catheter telling us? That the Cardiac Output is in the toilet. Despite good numbers for SVR and CVP--the heart can't supply the body with blood. Think about that. Blood gets INTO the heart (CVP) and is handled by the body in an approriate way (SVR). And you still are in 'shock'. Well--what is left? The heart is in shock? Right? Cardiogenic shock.

    Hypovolemic shock is because the heart doesn't have enough 'stuff' to push out. OK? We assume that the Cardiac Output of the Right Heart and the Left Heart are equal. (If they're not--we have big problems that show up in a hurry with PulmEdema and such.) So the Cardiac Output number is very low but the SVR is HIGH and the CVP is LOW. Don't you see how the body is doing its best to deal with lousy CardiacOutput (high SVR) and the heart is doing its best to deal with lousy circulating volume (low CVP)?

    Septic shock is because the body is infested with bugs and the capillaries and arterioles are open to the max and are leaking into the tissues almost as fast as blood gets into them. So the Cardiac Output starts as OK (goes down as volume is depleted) but the SVR is in the toilet. CVP starts OK--becomes low as volume is sucked into the tissues.

    You'll see that it's actually reasonable if you think: Is the blood coming in?(CVP) Is it being pumped efficiently?(Cardiac Output) Is it meeting a healthy environment?(SVR) And that is what you're really asking: Hypovolemic? Cardiogenic? Septic?

    But always remember!!!! Your Pt will tell you more about themselves than the Swan will.

    Papaw John
    Last edit by papawjohn on Oct 20, '05
  2. by   ghmccart
    It is important to know the physiological diff between cardiogenic shock, and septic scock, and throw in anaphylactic, hypovolemic, and neurgenic shock. taking the time to get these straight in your head is a good idea, even if you wont need the info regularly. we do know that the end result in any true shock in altered cellular metabolism and anaerobic happenings.