Question about Cushing's

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    Generally, as the ICP rises and results in cushing's response, the pulse pressure widens. Systolic goes up, diastolic goes down. I am wondering- what causes the diastolic pressure to drop? Thanks for any ideas...
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    I read your question and thought it was a good one. I asked a neurosurg NP that we work with, she didn't think that she had ever seen the answer but thought that it may be because of the occlusion of the posterior arteries when the brain starts to herniate. It may also have to do with the baroreceptors in the vessels that respond to pressure. She's going to research it and get back to me. I'll let ya know. GOOD QUESTION! Doesn't change our practice but it's an interesting FYI.
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    Thanks kc ccurn. Ive read up on this and asked around a bunch and havent found an answer for this one yet. If i come across anything interesting ill make sure to post it.
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    Quote from Lorus
    Thanks kc ccurn. Ive read up on this and asked around a bunch and havent found an answer for this one yet. If i come across anything interesting ill make sure to post it.

    I'm just a student, but of all the articles I've seen none of them mention the diastolic pressure going down. I've seen them talk about the systolic rising, but I have seen none talk about the diastolic going down. Can you show me where you saw this at? I was trying to find the answer to this question because I don't understand why the diastolic would go down either, but with everything I have looked at nothing says the diastolic goes down. Sorry if I have overlooked something. This bugs me just as much as it does you.
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    Hope this helps_" The Cushing reaction is a special type of CNS ischemic response that results from increased pressure in the cranial vault. For instance, when the cerebrospinal fluid pressure rises to equal the arterial pressure, it compresses the arteries in the brain and cuts off the blood supply to the brain. This initiates a CNS ischemic response which causes the arterial pressure to rise. When the arterial pressure has risen to a level higher than the cerebrospinal fluid pressure, blood flows once again into the vessels of the brain to relieve the ischemia. Ordinarily the blood pressure comes to a new equilibrium slightly higher than the cerebrospinal fluid pressure thus allowing blood to continue to flow to the brain".
    Cushings Triad-Hypertension, Bradycardia, Irregular Respirations
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    Quote from duckboy20
    Hope this helps_" The Cushing reaction is a special type of CNS ischemic response that results from increased pressure in the cranial vault. For instance, when the cerebrospinal fluid pressure rises to equal the arterial pressure, it compresses the arteries in the brain and cuts off the blood supply to the brain. This initiates a CNS ischemic response which causes the arterial pressure to rise. When the arterial pressure has risen to a level higher than the cerebrospinal fluid pressure, blood flows once again into the vessels of the brain to relieve the ischemia. Ordinarily the blood pressure comes to a new equilibrium slightly higher than the cerebrospinal fluid pressure thus allowing blood to continue to flow to the brain".
    Cushings Triad-Hypertension, Bradycardia, Irregular Respirations

    That was a very good explanation of Cushing's Triad. Thanks for the post.

    My main problem though is finding anywhere where it says the diastolic pressure goes down during cushings triad. I understand the dynamics of the systolic pressure rising, but I don't understand the diastolic falling.

    Thanks for the description.
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    since i don't know how to cut and paste, i'll try and answer from memory. it was from 'nursewise' and a case scenario where a young man was brought to the er with traumatic head injury. he eventually developed cushing's triad secondary to a subdural hematoma. it stated that a drop in the diastolic pressure was related to the decrease in cerebral perfusion pressure and decrease in cerebral blood flow during the ischemic event. hope i described it accurately enough....i googled "cushing's triad diastolic"....
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    Quote from DustinRN
    I'm just a student, but of all the articles I've seen none of them mention the diastolic pressure going down. I've seen them talk about the systolic rising, but I have seen none talk about the diastolic going down. Can you show me where you saw this at? I was trying to find the answer to this question because I don't understand why the diastolic would go down either, but with everything I have looked at nothing says the diastolic goes down. Sorry if I have overlooked something. This bugs me just as much as it does you.

    Sorry Dustin, just saw your post...

    Hudak, C. M. (1998). Critical Care Nursing: A Holistic Approach, (P. 620)

    Its not the most recent source, but thats where I saw it. The graph shows the diastolic pressure dropping even before the systolic begins to rise. Didnt see an explanation of this anywhere in the text.

    Im still looking around for more info on this..
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    Quote from Lorus
    Sorry Dustin, just saw your post...

    Hudak, C. M. (1998). Critical Care Nursing: A Holistic Approach, (P. 620)

    Its not the most recent source, but thats where I saw it. The graph shows the diastolic pressure dropping even before the systolic begins to rise. Didnt see an explanation of this anywhere in the text.

    Im still looking around for more info on this..

    NO PROBLEM!!!

    I'll try looking and see if I can find anything.
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    Hickey J. The Clinical Practice of Neurological and Neurosurgical Nursing 1997 p 312

    "Cushing's response is a compensatory ischemic response that reflexively raises the blood pressure in response to a rising ICP. If the blood pressure did not rise, the ICP would be equal to the blood pressure abd CBF would cease."

    The reason for a lowered diastolic is release of vasoactive agents (Lysosomes I think) from ischemic brain cells. This lowering of the diastolic can be seen in terminal shock when you are not perfusing the brain and these vasoactive substances are released.

    Cushings Triad is a LATE sign of rising ICP and usually occurs just before the brain herniates. By the time the patient exhibits this sign usually little can be done.

    PS Sorry but that edition of Hickey is the only one I have lying around at home - don't have anything more recent.


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