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109 Cards in this Set
- Front
- Back
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the epidural space is what kind of space
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POTENTIAL
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where is the epidural space the shallowest
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ANTERIORLY
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where is the epidural space the deepest
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POSTERIORLY and MIDLINE
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the epidural space is a series of what in the lumbar area
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discontinuous compartments
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when does the epidural space become continuous
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when the potential space seperating the compartments is opened up by injection of air or liquid
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the epidural space becomes less segmented in what area
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THORACIC
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the depth of the epidural space does what as it progresses more cephalad
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DECREASES
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what are the contents of the epidural space
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*fat
*venous plexus *segmental arteries *lymphatics |
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what is the primary component of the epidural space
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FAT
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lymphatics are found in what location of the epidural space
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LATERALLY
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segmental arteries are found where in the epidural space
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LATERALLY
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epidural fat is found primarily where in the epidural space
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*POSTERIOR
*LATERAL |
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the amt of epidural fat in the epidural space tends to correlate with what factor
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the general adiposity of the pt
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epidural fat decreases when
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with age
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what may be the primary factor in decreased dose requirements with aging
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decreases in epidural fat
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what is Batson's plexus
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extensive network of valveless veins
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Batson's plexus anastomoses with what
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EPIDURAL VEINS
*intracranial venous sinuses *pelvic veins *azygous system |
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communication b/t Batson's plexus and thoracic and abd veins results in what
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abd and thoracic pressure changes being transmitted to the epidural venous system
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what can dilate the epidural venous plexus
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*increased abd pressure
*mass compressing the vena cava |
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dilation of the epidural venous plexus increases what
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*probability of puncturing a vein during epidural placement
*spread of LA d/t decreased effective volume of epidural space |
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lymphatics in the epidural space are near what
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DURAL CUFF
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segmental arteries in the epidural space run where
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b/t the aorta and spinal cord
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T7 corresponds to what landmark on the body
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tip of scapula
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L4 corresponds to what landmark on the body
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iliac crest
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S2 corresponds to what landmark on the body
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posterior superior iliac spine
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cervical and lumbar curves of the spinal are convex where
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ANTERIORLY
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thoracic and sacral curves of the spine are convex where
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POSTERIORLY
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spinal curves will have a significant impact on what with LA
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spread of LA
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in the supine position what are the HIGH points of the cervical and lumbar curves
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*C5
*L5 |
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in the supine position what are the LOW points of the thoracic and sacral curves
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*T5
*S2 |
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the greatest thickness of the ligamentum flavum is where
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MIDLINE
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the greatest depth of the epidural space is where
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MIDLINE
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where does the needle go in a caudal
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sacral hiatus
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epidural fentanyl produces a blood level almost equivalent to what
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an IV dose
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what position should be avoided with an epidural unless desiring a lower block
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extremes of positioning such as sitting
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if you add epi to an epidural what is the effect on BP
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larger decrease
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what is the key element needed for success in an epidural placement
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POSITION
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an epidural has what effect on general anesthesia
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will decrease the amt of general needed
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the prone position for epidurals is most frequently used for what
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caudal epidurals in adults
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a pillow under the iliac crests with the prone position does what
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rotates the pelvis making it easier to enter the sacral canal
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how should the legs be in a prone position
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spread slightly with toes pointed inward
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what are the goals for holding the needle with an epidural
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SAME AS SPINAL
*absolute control of depth *tactile sensation of diff tissues & perferation of the dura |
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what is the most COMMON way to tell you have entered the epidural space
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loss of resistance
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the epidural needle is inserted with the bevel facing how
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LATERALLY
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when loss of resistance is felt with the needle when performing an epidural what is done next
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inject some of the saline & turn the bevel cephalad or caudad (90 degrees)
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when advancing the epidural catheter what may facilitate the advancement
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injection of air or saline
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if the epidural catheter does NOT advance easily without meeting resistance what could be the cause
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*in the wrong place
*up against something |
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if the epidural catheter won't advance out of the end of the needle what can be done
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withdraw the catheter and reposition the needle
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if the epidural catheter has advanced any distance out the end of the needle but not far enough what must be done
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remove the catheter and needle as a unit and start over
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a test dose if given with an epidural to affirm what
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that you are not:
*intravascular *subarachnoid |
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if you are intravascular with your epidural what will be the s/s after the test dose
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*ringing in ears
*increased HR >20bpm above baseline |
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if you are subarachnoid with your epidural what will occur after a test dose
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rapidly developing block at a level higher than anticipated
(pt will become more numb than should) |
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if the pt has a septum in their epidural space what will this cause
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will not allow anesthetic to get from one side to the other
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what should be used to improve adhesion when securing the epidural catheter
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*benzoin
*matisol |
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what type of dressing is preferred for long term use of an epidural catheter
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sterile occulusive
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the most common test dose includes what agents
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lidocaine with epi
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how should subsequent doses of medication for an epidural be performed after the test dose
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incrementally and only after aspiration
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what is the usual amt of dosing given in each increment after a test dose is perfomed with an epidural
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5 ml at a time
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how is puncture perfomed for a caudal epidural
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puncture sacrococcygeal membrane at 45 degree angle until bone is contacted
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what is done after puncture with a caudal epidural
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withdraw slightly and redirect needle in a shallower plane
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after puncture and redirection of needle with a caudal epidural what is performed next
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advance needle 1-2 cm into the caudal canal
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after needle is advanced into caudal canal with caudal epidural what is perfomed
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rapidly inject 5ml saline while palpating the sacrum
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after injecting saline with a caudal what implies correct placement or at least not sub-q placement
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absence of midline bulge
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what is the early site of action for an epidural
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segmental spinal nerves traversing the epidural and paravertebral spaces
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what is the later site of action for an epidural
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subdural locations including within the spinal cord
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what is the main membrane that keeps drug away from the spinal cord
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arachnoid
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what are the LA used for epidurals
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*chloroprocaine
*lidocaine *mepivacaine *etidocaine *bupivacaine *levobupivacaine *ropivacaine |
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what LA used for epidurals is rapid onset and short duration
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chloroprocaine 2% and 3%
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what LA used for epidurals is intermediate onset and intermediate duration
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*lidocaine 2%
*mepivacaine 2% |
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what LA used for epidurals is intermediate onset LONGER duration
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etidocaine 1%
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what LA used for epidurals is slower onset and longer duration
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*bupivacaine 0.5-0.75%
*levobupivacaine 0.5-0.75% *ropivacaine 0.75-1% |
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what are the factors affecting epidural dose
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*inter pt varabilty
*injection site *age *ht and weight *prenancy |
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the most important determinant for affecting epidural dose is what
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injection site
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what kind of dosage adjustment is needed with increased age
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DECREASED
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what are the reasons for needing a dose adjustment in increasing age
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*decreased epidural fat content
*less compliant epidural space *decreased ability of drug to leak out of intervertebral formina |
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some studies suggest what kind of dose adjustment in pregnancy
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REDUCED
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with a lumbar epidural injection site what amt of LA will typically produce a mid-thoracic sensory block
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20 ml
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position has what effect with a lumbar epidural injection site
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little effect
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C8 corresponds to what dermatone
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little finger
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what is the best way for dosing an epidural for labor
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*establish block with 0.625%-0.125% bupivacaine
*infusion of the same |
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continuous infusions for labor epidurals contain what
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bupivacaine 0.05%-0.125% with 1-5 mcg/ml of fentanyl
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infusion rates on continuous infusions for labor epidural are what
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vary from 10-18 ml/hr
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what is a perineal or delivery dose with an epidural
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10 ml of LA
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if the pt is uncomfortable near delivery but still needing to push what can be done with the epidural
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give
*2% chloroprocaine *1% lidocaine |
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if the surgeon is planning instrumented delivery what can be done with the epidural
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give
*3% chloroprocaine *2% lidocaine |
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what are adrenergic agonists that can be added to an epidural
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*epi
*phenylephrine |
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what concentration of epi can be added to an epidural
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5 mcg/ml = 1:200,000
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addition of epi to a epidural does what
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*significant prolongation of lidocaine, mepivacaine & chloroprocaine
*reduces peak plasma levels of LA |
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what amt of sodium bicarb can be added to an epidural
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1 meq to 10 ml LA
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what does the addition of sodium bicarb do with an epidural
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*speeds onset (more drug in non-ionized form)
*may improve the density of the block |
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anytime an epidural is bolused what should be done
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should first aspirate b/c the catheter can migrate into a blood vessel or the subarachnoid space
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what are the keys to prevention of systemic toxicity with an epidural
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*an adequate test dose
*incremental injection of the LA solution |
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intravascular injection with an epidural would most likely be via what
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epidural vein
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what are the INITIAL affects to the CNS with intravascular injection with an epidural
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EXCITATION d//t inhibition of inhibitory neurons in cortex
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what are the affects to the CNS from higher concentrations of medication intracvascularly injected with an epidural
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inhibition of BOTH inhibitory & excitatory pathways
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intravascular injection with an epidural can have effects on what systems
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*CV
*CNS |
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with CV effects from intravascular injection with an epidural what med has narrower margin of safety and why
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*bupivacaine
*d/t slower dissociation from Na channels |
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what meds have lower cardiotoxic potential and may be advantageous for an epidural
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*ropivacaine
*levobupivacaine |
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subarachnoid injection with an epidural can lead to what
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high spinal or possibly total spinal
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what is the prevention for subarachnoid injection with an epidural
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*test dose
*incremental injection |
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what is the management for an inadvertant subarachnoid injection with an epidural
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*BP and HR support
*support of ventilation, intubation if needed |
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what should be considered with an epidural if an unexpected but less severe and more slowly developing HIGH block occurs
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SUBDURAL location
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what type of complaint is common following regional anesthesia tech
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BACK PAIN
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what are the potential etiologies for back pain with regional anesthesia
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*needle trauma
*LA irritation *ligamentous strain |
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what are the possible etilogies of neurologic injury with an epidural
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*direct needle trauma
*vascular injury with subsequent neural ischemic insult *epidural hematoma |
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what is the key to an good outcome with an epidural hematoma
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early detection
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outcome with an epidural hematoma is significantly worse if treatment is delayed more than what
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8 hrs
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if you are unable to remove the epidural catheter what should be done
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place the pt back in the position they were in when you placed the catheter
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what procedures are safer with regional anesthesia
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*c-section
*hip sx |
