Questions about putting in an epidural?

  1. Hi all,

    Had a few questions about epidurals and would greatly appreciate any answers!

    1. I was wondering, when you put in an epidural, how do you know it is in the epidural space and not the subdural/intrathecal space?

    2.)What would be some signs/symptoms that it was placed too far?

    3.Is it possible for the epidural to "migrate" into the intrathecal space and basically turn into a spinal?

    4.) If the epidural needle pokes a hole in the dura, can the epi medication travel through it into the subdural space?

    Thanks!
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  2. 4 Comments

  3. by   wtbcrna
    I saw this is your first post, if I may ask what is your reason for asking that way I or we can tailor our responses better to answer your questions.
  4. by   Nursing2102
    I now work on a surgical oncology floor and often patients come to the unit with a PCEA in place. Just curious about how epidurals work and how they're put in along with potential complications that may arise. Thanks!
  5. by   wtbcrna
    The most common way to tell if in epidural is in the right place is usually by a loss of resistance technique. Loss of Pressure Epidural Injection - YouTube

    Once the epidural is in place it is commonly tested with epidural test dose to make sure the epidural is not in a vein/vasculature or past the dura. Commonly this is done with a mixture of lidocaine and epinephrine. When and if the the test dose is positive (bad sign) then if it is past the dura the patient will have almost instantaneous numbness of the lower extremities since epidurals generally take several minutes to set up, but if it is in the vasculature the heart rate will temporarily increase d/t the epinephrine.
    It is technically possible for the epidural catheter to migrate in or out. It is much more common for the epidural catheter to be pulled out. I have not personally seen an epidural catheter migrate into or past the dura. There multiple reasons that epidural catheters failed to respond as expected. Failed epidural: causes and management. - PubMed - NCBI
    Yes, the epinephrine can travel into the subdural space, but small amounts of epinephrine are essentially inconsequential and often used in small doses along with local anesthetics in spinals. You would be unlikely to notice any response to subdural epinephrine except for possible small increase in the time for single dose of local anesthetics to wear off.

    Epidural Nerve Block: Overview, Indications, Contraindications
    Last edit by wtbcrna on Mar 16
  6. by   offlabel
    1. I was wondering, when you put in an epidural, how do you know it is in the epidural space and not the subdural/intrathecal space?

    The only way to truly know is when the epidural is working properly.

    2.)What would be some signs/symptoms that it was placed too far?

    There isn't really a "too far". If the catheter is advance too much, a one sided or patchy block might result, but for most purposes 4-6 cms is about as far as it should be placed into the epidural space.

    3.Is it possible for the epidural to "migrate" into the intrathecal space and basically turn into a spinal?

    Anything is possible and, yes, it has happened, but it isn't common and would be the result of some very unusual circumstances. Migration into an epidural vein is more common and a sign of that is when the patient begins to have more pain.

    4.) If the epidural needle pokes a hole in the dura, can the epi medication travel through it into the subdural space?

    Wet taps happen from time to time and are most usually followed by a successful placement of the epidural catheter. There should be no concern of the mediation entering the rent in the dura, mostly because the CSF in the thecal sac is under positive pressure and is leaking out, preventing anything from "leaking in". Not really an issue at all.

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