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208 Cards in this Set
- Front
- Back
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The spinal column runs from the _____ to the _____, with (#) vertebrae.
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foramen magnum to the sacral hiatus, 33
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What are the 4 sections of the spinal column?
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cervical: 7 vert, convex
thoracic: 12 vert, concave lumbar: 5 vert, convex sacral: 5 vert w a fused coccyx. concave |
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What happens to the intervertebral disks in the elderly?
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become ossified or nonexistent (also w surgical fusion)
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This approach hits the paraspinous muscle and ligamentum flavum, and does not traverse the interspinous or supraspinous ligaments
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paramedian approach
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How can you determine if you are returning CSF or NS that has already been injected during the loss of resistance technique?
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CSF has glucose, and will warm your forearm (ew, gross!)
thiopental and lidocaine will precipitate, CSF will not halo effect |
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Site of action of LA in the spine
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on the nerve roots where dura is thin (except S1-S1-- more difficult to anesthetize sciatic nerve)
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What does the line betwen the iliac crests landmark?
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L4-L5 interspace
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What is the pressure in the epidural space?
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subatmospheric pressure
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How do you determine how many cm to place a catheter into the space?
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whether it is multiport or uniport
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Taylor approach
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go between L5 and S1, largest interspace in the body for spinal/epidural placement
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What is the angle of the needle for entry into cervical spine or lumbar spine?
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straight on, 0 degrees
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What is the angle of the needle for entry into the mid thoracic spine?
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60 degrees
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What is the angle of approach for needle entry into the lower T/upper L spine?
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40 degrees
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Components of a vertebra
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- vertebral body
- pedicles (2 anterior) - laminae (2 posterior) - transverse process (junction of pedicles and laminae) - spinous processes (joining of lamine) - intervertebral disks (herniate and cause back pain) |
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How many spinal nerves are there?
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31
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What are the 3 layers of spinal coverings?
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1. dura mater (outermost)
then subdural space (potential space) 2. arachnoid mater (middle) then subarachnoid space (cranium to S2) 3. pia mater (innermost) then caudal canal (Epidural space) |
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The spinal cord terminates at the _____ and the ______ extends down and anchors in the lower sacral region.
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conus medullaris, filum terminale
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The spinal cord extends from the the ____ to _____ through the vertebral column.
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foramen magnum, L1-L2
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____ covers the spinal cord and spinal nerves, and ends with the spinal cord at L1-L2
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pia mater
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This space is located between the arachnoid mater and pia mater and holds the CSF.
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subarachnoid space
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____ ends at the S2 and creates the _____ sac.
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dura mater, dural sac
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This is the space between the dural sac and the coccyx
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caudal canal
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The spinal cord vessels are located in what layer?
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pia mater
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Not everyone has this nerve:
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coccygeal
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Describe the nerve distribution out of the spinal cord?
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cervical - 8 nerves (exit above vert)
thoracic- 12 (exit below vert) lumbar- 5 sacral- 5 coccygeal- maybe 1, maybe none |
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This area is the "horse's tail," in the lower lumbar and sacral nerves that extends past the spinal cord.
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cauda equina
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What is the big ass ligament that runs down your back from C7 to the sacrum, and has "high liability?" --- this one's for you london!!...
connects tips of spinous processes |
supraspinous ligament
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Where is the interspinous ligament found?
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between posterior spinous processes
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This ligament runs from the foramen magnum to the sacral hiatus, connects the laminae, is thickest in the middle (making it hard to get to the meninges) and is a very dense narrow band.
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ligamentum flavum
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What happens if a needle is inserted into the ligamentum flavum?
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will stick like an arrow in a target, will not sag
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What are the advantages of spinal/epidural anesthesia?
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- avoid hazards of general
- pt alert earlier post op - lower incidence N/V - better pain control w less narcotics |
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What are the absolute contraindications of spinal/epidural anesthesia?
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- pt refusal
- infection at injection site - severe coagulopathy - documented LA allergy |
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Unintentional dural puncture could result in ...
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CSF loss, brain herniation
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What are the relative contraindications of spinal/epidural anesthesia? (There's a lot of these!)
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- uncorrected hypovolemia
- untreated chronic HTN - aortic/mitral stenosis (esp in SAB, decr afterload) - incr ICP - MS (demyelination makes hypersensitive/toxic effects to LA) - HIV (can introduce virus into spinal canal) - sepsis - major sx above umbilicus - severe spinal deformity (may be traumatic) - may exacerbate chronic back pain/headache - arthritis, spinal stenosis, lumbar fusions |
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What are the considerations for providing spinal/epidural anesthesia in pts w HTN?
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dry due to vasoconstriction and redistribution of total blood volume --> sympathectomy will result in greater vasodilation and decr venous return -- the higher the SBP, the more precipitous the drop in BP
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This is the single injection of an LA into the subarachnoid space usually at the lumbar level, often w intrathecal narcotics.
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spinal anesthesia
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Where is spinal injected?
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commonly L3-L4, but the largest interspace is L5-S1 (taylor approach)
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In spinals, small needles...
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decr PDPH
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In spinals, large needles...
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improve tactile sensations
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In spinals, pencil-point needles---
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decr PDPH
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In spinals, side injection needles with large holes...
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incr CSF but be careful to have the entire hole in the subarachnoid space
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This is the oldest needle, rarely used, and helpful in elderly and obese cases.
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quincke sounds kinky!
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This needle is more commonly used, has a tiny hole, and if you get return, you're almost definitely in the right place.
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whitacre
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This needle is commonly used, very long, and more likely to only get a partial block
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sprotte
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This needle is cheap, and is a combo of whitacre and sprotte
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pencan
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How does needle choice influence PDPH?
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- 2% incidence in women between 16-35 w quincke
- other needles incidence decr to 0.2% |
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What are the most important factors affecting block height in SAB?
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1. baricity of solution (usually mixed in D5, D7.5, D10, higher density will sink in canal)
2. position of pt (sitting during injection, supine or lateral immediately after depending on surgical site) 3. drug dosage (Concentration x volume) 4. site of injection |
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How does CSF baricity compare to H20?
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its the same!
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How do you make a solution isobaric? (same baricity as CSF)
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mix w NS or withdraw and mix w equal parts of CSF
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How do you make a solution hypobaric?
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mix w sterile H20
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What is the SAB consideration for elderly population?
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lower dose if > 80 yrs
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What is the preferred spinal administration for someone 5'-5'10"?
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hyperbaric bupivacaine or ropivacaine 11.25mg at T4 level w additive opioids
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How does pregnancy/obesity affect SAB?
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can give lower dose because space is compressed w incr intra-abdominal pressure
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What role does volume place in SAB compared to epidural?
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with spinal, you're in a closed space right on the nerves, so less volume is required -- whereas epidural must diffuse through dura to take effect -- more volume required
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How does addition of a vasoconstrictor affect SAB?
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epi potentiates LA used -- decr reuptake into bloodstream and has its own LA characteristics
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Do rate of injection, gender or weight affect SAB height?
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NOPE!
hypobaric soln- may be more sensitive to rate of injection wt- adjust for morbid obesity *HEIGHT OF BLOCK DICTATED BY DOSAGE IN SPINAL* |
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A sympathetic block can extend ____ dermatomes higher than the sensory block.
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2-6
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A motor block can extend ____ dermatomes lower than the sensory block.
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2
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Isobaric
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stays where you put it -- LA has same density or specific gravity as CSF (1.003-1.008), ex: NS
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Hypobaric
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"floats up" -- lighter than CSF, LA has density/specific gravity less than CSF (<1.003),
EX: sterile H20 |
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Hyperbaric
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settles to dependent aspect of subarachnoid space -- heavier than CSF, LA has spec gravity/density > CSF (>1.008),
ex: dextrose 5/7.5/10 |
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LAs are ____ to nerves.
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toxic
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What effect does incr glucose of LA soln (hyperbaric) have on nerves?
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glucose adds to crystalization around nerves in cauda equina -- cause cauda equina syndrome
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Hypobaric injections will spread _____, hyperbaric solutions will spread ______, and isobaric solutions will spread _____.
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hypo- cephalad
hyper- caudad iso- same place but may spread cephalad |
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How does raising the patient's shoulders affect SAB injection?
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narrows the space, so more helpful if pt relaxes the shoulders for placement
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Describe sitting position for SAB
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with legs hanging over side of bed, have pt hug a pillow and place feet on stool w no wheels, assistan keeps pt from swaying, then curve back like a mad cat
(up in the bed is quicker but not optimal) |
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Describe lateral decub position for SAB
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pt must be parallel to edge of bed, legs flexed to abdomen, chin to chest , hips and shoulders vertical
men have narrower hips, women got big buddha hips |
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Advantages of lateral decub position for SAB
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- blood patch - placing 20 cc autologous blood in epidural space to prevent/treat PDPH
- hip fx or lower extrem pain, use isobaric soln |
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What is the IVF plan for SAB placement?
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- 500 cc bolus prior to injection, then at time of injection infuse 10-20 cc/kg
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What is the premedication for SAB injection?
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if not in labor/c-section case, give versed and fentanyl and O2 prior to neuraxial anesthesia, local lidocaine (may burn)
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List the layers the needle must pass through for SAB
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1. skin
2. subcutaneous fat 3. supraspinous ligament (avoided w paramedian approach) 4. interspinous ligament (Avoided w paramedian approach) 5. ligamentum flavum 6. epidural space 7. dura mater 8. arachnoid mater 9. subarachnoid space |
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What are the meds required for placement of SAB?
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- LA
- epi/neosynephrine - opioids |
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In this approach, you palpate the largest interspace, find the spot that is midway between spinous processes and mark, insert needle anywhere between C7 and buttcrack (usually second fat roll)
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midline approach
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In this approach, you palpate the largest interspace, find the inferior spinous process mark 1 cm lateral and 1 cm down
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paramedian approach
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Why is it important to let betadine dry or wipe off excess before SAB puncture?
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can cause chemical meningitis if needle introduces it to space
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What are the steps of SAB?
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1. prep back w betedine or chloroprep
2. drape back 3. draw up and label meds, uncap needles/catheters 4. find L4 using iliac crests, feel interspaces above and below LR 5. mark where you want to inject LA 6. inject 3 cc lidocaine 1% plain (1 cc on each side and 1 cc midline) 7. allow time for LA to kick in 8. place 18 g needle at same site, parallel to fibers, do not hub it 9. insert whitacre or sprotte needle through introducer -- when "pop"/change in resistance occurs, stop advancing needle! |
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Why is parallel insertion of the needle (bevel sideways) preferable to vertical insertion (bevel facing cephalad)?
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sideways/parallel - faster/better healing of puncture hole
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After you've reached the subarachnoid space in placing an SAB....
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1. remove stylet from needle
2. allow CSF to come back into hub 3. rotate needle to all 4 quadrants 4. connect syringe to local admixture (LA + OPIOIDS)-- dont allow needle to move now 5. aspirate CSF - will see a swirl! 6. inject LA, aspirate again at the end 7. remove introducer and needle as one and position the pt (supine or lateral decub) |
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T4 dermatome
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nipple line
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T6 dermatome
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xiphoid
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T10 dermatome
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umbilicus
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C8 dermatome
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fingers (4/5 digits)
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C4-5 dermatome
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clavicles
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posterior T7
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scapula
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S2-S5
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hemorrhoidectomy
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L2-L3 sx
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foot surgery
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L1 sx
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lower extrem surgery
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T10 sx
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hip sx/turp
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T6 sx
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lower abd sx
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T4 sx
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upper abd sx
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What is the dose for lidocaine 5% at T10 and T4?
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T10- 30-50 mg
T4- 75-100 mg |
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What is the dose for bupivacaine (0.5-0.75%), ropivacation (0.5-0.75%), and tetracaine 0.5% at T10 and T4?
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T10- 6-10 mg
T4- 12-15 mg |
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What LA is the likely culprit of TNS and Cauda Equina syndrome (incontinence, foot drop)?
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lidocaine
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Methods of checking SAB level
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- etoh pad
- ice water - tongue blade - pinprick - nerve stimulator |
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What fiber am I?
0.25 microns preganglionic autonomic fcn |
B fibers
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What fiber am I?
0.5 microns temp and dull pain fcn unmyelinated, slow, first affected, what you're checking when you assess level of block |
C fibers
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What fibers are you checking w nerve stimulators?
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A fibers
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Which fiber am I?
0.5 microns temp and sharp pain fcn |
A delta
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What fiber am I?
0.75 microns muscle spindle, muscle tone fcn |
A gamma
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What fiber am I?
0.75 microns light pressure, touch fcn |
A beta
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What fiber am I?
1 micron somatic motor, proprioception fcn |
A alpha
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Indications for SAB
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- C-Section
- TURP: can report s/s of perforated bladder, hypervolemia, turp syndrome, hypovolemia (N/V, seizure) - lower extrem sx: afferent block for decr surgical stress, speeds recovery, decr arterial and venous pressure, decr risk fo VTE, decr EBL |
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Systemic HTN, bradycardia, and subcutaneous vasodilation above the level of transection are due to _____ stimulation.
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carotid sinus stimulation
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Labor epidural should be placed ____ cm into the space due to prolonged need for labor analgesia and movement may accidently displace the catheter.
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4-6 cm
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Don't use SAB when...
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- unstable pt
- difficult airway |
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Autonomic dysreflexia
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- can be caused by full bladder
- T6 Level transection - GA doesnt guard against this w pt w T6 lesion or higher, so you have sympathetic response below the level of the lesion unabated by parasympathetic above the lesion (Baroreceptors), so you have high BP and decr HR (Can be set off by painful surgical stim) |
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What are the possible complications of SAB?
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- pain on injection
- urinary retention (blocked S2-S4 root fibers decr urinary bladder tone and inhibits voiding reflex) - vascular injury - nerve injury - high spinal anesthesia (rare) - cardiac arrest (in pts w high vagal tone such as young athletic men) - meningitis from sinus infection - backache - hypotension (#1 complication!! often w c-section) - Nausea - PDPH |
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What factors enhance incidence of PDPH?
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- young age
- female - larger needle - if needle bevel cuts dural fibers transversely - pregnancy (incr elasticity of fibers from progesterone) - multiple dural puncture attempts |
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Does ambulation incr risk of PDPH?
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nope
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If a pt already has a PDPH, what effect will ambulation have?
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incr pain
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Etiology of PDPH
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hole does not heal and CSF leaks out over time - brain is dehydrated, being pulled down into tentorium, not likely to be fatal but painful
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How is a PDPH treated?
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- supine position relieves pressure and pain
- blood patch: inject 15-20 mL of autologous blood at level of dural puncture or one space below drawn sterile from a peripheral site into subarachnoid space, inject until pt cant stand it any more or 20 cc -- can give another 24 hrs later, if this doesnt work continue giving fluids, bedrest, analgesics - caffeine, NSAIDs, tylenol, stool softeners |
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Presentation of PDPH
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- Headache is bilateral, frontal or retroorbital, occipital and extending into neck
- photophobia/diplopia - nausea - hallmark sign "better when i lie down" - 12-72 hrs and last 7-10 days or longer - worsens w sitting up - goes from back of head to front of head |
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How does caffeine help with PDPH?
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stimulates CSF production and vasoconstriction of intracranial vessels
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How do you decide between SAB vs epidural?
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- longer procedure (>3-4 hr) use epidural
- onset of anesthetic (spinal faster) - if needs post op analgesia, use epidural - if coexisting diseases, like severe stenosis, use epidural and load slowly to allow time for equilibrium and stabilization - inpt can use epidural, outpt use spinal |
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What's hiding in the epidural space?
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- fat (posterior and lateral)
- venous plexus (anterior and lateral) - lymphatics - arteries |
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What do you have to poke through to place an epidural?
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skin --> subcutaneous tissue --> supraspinous ligament --> interspinous ligament --> ligamentum flavum--> epidural space
stop short fo subarachnoid space -- not as deep as spinal! |
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What are the landmarks to look for identification when placing an epidural?
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- C7
- superior aspect of ischial spines (L4-L5) - spinous process - transverse process - 12th rib |
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Where does the spinal cord end?
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L1-L2 in adults
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Epidural space is....
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potential, not a real space!
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Unlike epidural space, subarachnoid space is...
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real space filled w fluid and nerves!
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What are the sites of action of epidural anesthesia?
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1. spinal nerves in paravertebral spaces (LA seep through intravertebral foramina)2. dorsal root ganglia adjacent to dural cuff (relatively thin region)
3. individual ant. and post. spinal nerve roots within dural root (where dura mater is thin, rapid diffusion - fastest- through arachnoid granulations) 4. spinal nerve rootlets (fine nerve filaments w large surface area, reach through adjacent dural cuff) 5. peripheral regions of spinal cord (CSF bathes these areas) 6. brain (by cephalad spread) |
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What are the physiological effects of epidural blockade?
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- vasoconstrictor fibers (Below T4)
- Cardiac accelerator fibers (T1-T4) |
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You can avoid a major sympathectomy by restricting level of blockade to ____, as with TURP pts.
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T10
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Epidural for lower abd sx
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very suitable
T7 ht of block desired reduces bleeding |
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Epidural for c-section
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very suitable
T4-T6 ht of block desired avoid aortocaval compression |
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Epidural for urological sx
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suitable
T9-T10 SAB preferred |
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Epidural for open kidney sx
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suitable
T6 ht of desired block may need IPPR (intermittent positive pressure respiration) |
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Epidural for lithotripsy
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very suitable
T6-T7 block ht desired may not need anesthesia w epidural |
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Epidural for vaginal sx
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very suitable
T10-T12 block level desired ht reduced bleeding, may need higher block if abd opened |
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How do you control height of block?
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according to volume and dose-- always place needle at same spot but actual drug dose and volume determine height of block
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How do you prep for epidural placement?
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1. identify suitable pt
2. get equipment (single-shot or cath placement, know epidural kit, tape to keep in place) 3. determine technique to be utilized (loss of resistance, hanging drop) |
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This technique is used for thoracic epidurals, and you put a drop of LA at edge of needle and wait til it gets sucked in -- risky bc may end up in lung!!
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hanging drop
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Epidural needles
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hustead, touhy, CSE
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Spinal needles
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quincke, sprotte, whitacre
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Caudal needles
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22 gage single shot, 20 gage angiocath, hustead or touhy, mostly for kiddies
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Subarachnoid space ends at...
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L5-S1
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What factors affect spread and duration of epidural?
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- dose
- volume ****** - concentration - presence of epi (high H+ concentration, pos charge that blocks Na channel; initial decr in onset outside lipid membrane, but once its on the other side, it incr onset at Na channel site; adding epi gives more potent block-- potentiates!) - class of anesthetic (ester vs amide) - opioids (fentanyl is lipophilic so gets in there quicker!) - positioning |
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Spread and duration for epidural is determined most by
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volume
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Spread and duration for spinal is determined most by
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dose
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Isobaric cocktails are used often in ___ sx.
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hip
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When might you use hypobaric cocktails?
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in jackknife position - like in hemorrhoid sx
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What are the preop meds for epidural placement?
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reglan, versed, Na citrate, beta blocker (PRN)
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What labs must be drawn before epidural placement?
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coags, platelets (don't want less than 100,000)!
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Whats the test dose for epidural analgesia?
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1.5% xylocaine w 1:200,000 epi (CV marker, see HR incr immediately)
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Techniques for providing epidural analgesia include the ____ and ___ methods.
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epidural and caudal
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Caudal method is not typically used because....
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technically difficult and requires large volumes of medication, which could lead to toxicity and incr maternal morbidity
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____ epidural analgesia is most frequent method for delivery to laboring parturient. Viewed as the cadillac of anesthesia -- requested early in course of labor
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lumbar epidural
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Usually lumbar epidural is placed when mom is ___cm dilated, but if there's twins in there, you can put it in w ____ cm dilation.
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4 cm, 2 cm w twins or if pitocin turned on
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You can offset the pain in the early course of labor with ______ which has been shown not to prolong the transition from the latency to the active phase of labor.
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intrathecal opioid placement
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What are the choices for LA in laboring pts?
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bupivacaine, lidocaine, chloroprocaine, ropivacaine
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____ is most frequently used LA for laboring analgesia bc it causes less motor blockade, is highly protein bound (minimal fetal exposure), and bc small concentrations can be used to achieve excellent anesthesia.
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bupivacaine
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Routinely ____ and ____ aren't given for continuous infusions for analgesia bc the profound motor blockade that can occur w small concentrations of _____ and the short analgesic latency of _____.
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lidocaine and chloroprocaine, lidocaine, chloroprocaine
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____ and ____ are usually reserved for providing top off doses, c-sections, or testing catheter for proper placement.
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lidocaine and chloroprocaine
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_____ is reported to cause less motor blockade while providing excellent analgesia.
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ropivacaine
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____ dosing is important in epidural drug admin.
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incremental
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What are possible approaches for epidural placement?
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midline (most often), paramedian, caudal
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What are the possible techniques for epidural placement?
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loss of resistance**, hanging drop
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3 tips for epidural placement
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1. insert below L2
2. place needle approx 3 cm into intraspinous ligament 3. use loss of resistance technique (3 cc NS preferable to air!) |
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equipment for epidural block placement
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EKG, O2, code cart, intubation equipment, BP cuff, spo2 monitor, assistants!, epidural tray, LA solution, "Test dose", syringes, ephedrine (Draw up), medications (LA, epi, sodium bicarbonate to add to solution- 4.2% peds, 8.4% adults, 1/4-1 cc for every 10 cc LA; opioids)
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What is the most important monitor during epidural analgesia??
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the nurse in the room watching the pt!!!
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Important things to monitor during epidural analgesia:
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- VS
- fetal HR - contractions (if laboring) - level of block - level of maternal consciousness/awareness (if indicated) - oxygenation - urine output |
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Epidural level and duration is dependent on...
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dose, VOLUME, concentration of LA, presence/absence of Epi
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Epidural level and duration is NOT dependent on
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1. weight, age, height, rate of injection
2. baricity of LA 3. maternal position (only little bit of influence) |
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Process of epidural placement
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1. prep sterile field/gloves
2. prep back w betadine/chloraprep 3. drape back 4. draw up meds, remove covers from needles/caths 5. find L4 using iliac crests - feel interspaces above and below, mark where you want to inject local 6. inject 3 cc lidocaine 1% (1 cc on each side and 1 cc midline), allow time to take effect 7. place touhy at same site, insert until seated well (firm when tapped in intraspinous ligament) 8. remove stylet |
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Describe loss of resistance technique
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- glass/plastic luer-lock syringe w 2-3 cc NS w small air bubble (not air only, creates painful hotspot x2 hrs)
- place glass syringe on touhy (tight but dont shear plastic from end of needle) - find loss of resistance (Steady/intermittent pressure w advancement) - loss of resistance occurs due to negative pressure in potential space which has adipose and connective tissue w a prominent venous plexus but no free fluid exists |
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Using air for loss of resistance technique may cause....
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pneumocephalus, venous air embolism
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Using saline during loss of resistance technique may mask...
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a wet tap
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Most epidural caths are stiff w reinforced wire, and have _____ ends that are marked so that you know you are putting the correct end in.
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multiorifice
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When is combined spinal epidural used?
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- labor: intrathecal narcotic with or without LA epidural infusion
- surgical procedure: SAB w epidural infusion for post op acute pain mgmt |
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This is the technique for spinal/epidural needle placement where you put the back of your hand up against the pts back and stabilize the needle so you don't move it around after it's in the right place
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bromage grip
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Indications for CSE
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- lower levels of LA used if SAB for surgery and epidural for post op analgesia
- more rapid onset and density of SAB for surgery than epidural if surgery is prolonged - intrathecal narcs in early labor followed by epidural for active labor |
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Epidurals have ____ differential sympathetic block.
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NO
sympathetic level = sensory level |
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Epidurals have differential motor blockade of ____ segments below the sensory level.
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2-4 segments
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What is the difference in volume required for spinal vs epidural?
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much more volume in epidural -- 15-20 cc
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Spinal has a sympathetic block ___ levels above sensory and motor block ____ levels below sensory.
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sympathetic 2 above
motor 2 below |
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You shouldn't give bupivacaine 0.75% to the OB population due to this nasty little side effect
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cardiotoxicity
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Chloroprocaine epidural
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2-3% concentration
45 mg dose 5-15 min onset 30-90 min duration |
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Lidocaine epidural
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1-2% concentration
25 mg dose 5-15 min onset 60-120 min duration |
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Bupivacaine epidural
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0.25-0.75% concentration
7 mg dose 10-20 min onset 120-140 min duration |
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Ropivacaine epidural
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0.25-0.75% concentration
9 mg dose 10-15 min onset 120-160 min duration |
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Epidural test dose
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lidocaine 1.5% with epi 1:200,000
3 cc |
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What does epidural test dose tell you?
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incr HR/BP if intravasc
decr BP if in subarachnoid space |
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Positive test dose for epidural
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pull back 2 cm (bc you have accidental subarachnoid/intravascular placement)
incr HR 20% within 30 sec (dont give it during a contraction!) intrathecal injection of 45 mg of lidocaine will cause spinal anesthesia within 3-5 min post-injection (wait 3-5 min before dosing epidural because it takes that long to take effect!) |
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Negative test dose for epidural
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does not indicate proper placement into epidural space
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In giving epidural injection, you should give ___cc of LA every 5 min -- don't hurry!
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3-5 cc
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Once you aspirate fluid from a newly placed catheter, what could it be???
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- CSF (if positive for glucose)
- lidocaine + thiopental creates precipitation - CSF + thiopental = no precipitation, do glucose test! |
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Lidocaine epidural %
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intraop 1-2%
postop/labor 0.25-0.5% |
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Bupivacaine epidural %
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0.25-0.75% intraop
0.0625-0.125% postop/labor |
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Ropivacaine epidural %
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0.2-0.5% intraop
0.1% postop/labor |
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Chloroprocaine epidural %
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2-3% intraop
N/A postop/labor |
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Indications for epidural anesthesia
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- labor analgesia/c-section
- turp - lower extrem sx - procedures of unknown length |
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What is autonomic dysreflexia?
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Autonomic dysreflexia (AD), also known as autonomic hyperreflexia, is a potentially life threatening condition which can be considered a medical emergency requiring immediate attention. AD occurs most often in spinal cord-injured individuals with spinal lesions above the T6 spinal cord level. Acute AD is a reaction of the autonomic (involuntary) nervous system to overstimulation. It is characterised by severe paroxysmal hypertension (episodic high blood pressure) associated with throbbing headaches, profuse sweating, nasal stuffiness, flushing of the skin above the level of the lesion, bradycardia, apprehension and anxiety, which is sometimes accompanied by cognitive impairment.[1] The sympathetic discharge that occurs is usually in association with spinal cord injury (SCI) or disease (e.g. multiple sclerosis). AD is believed to be triggered by afferent stimuli (nerve signals that send messages back to the spinal cord and brain) which originate below the level of the spinal cord lesion. It is believed that these afferent stimuli trigger and maintain an increase in blood pressure via a sympathetically mediated vasoconstriction in muscle, skin and splanchnic (gut) vascular beds --- wikipedia
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Complications of epidural anesthesia/analgesia?
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- hypotension
- parasthesias - accidental dural puncture - subdural injection - massive epidural analgesia - accidental intravasc injection (toxicity) -- seizure - backache (Residual 2-3 days after, localized) - assymetrical sensory block- often due to scar tissue, can use gravity and volume to try to move it around epidural space - headaches -- PDPH |
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Why do epidurals cause hypotension?
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aortocaval compression- chief reason for hypotension -- positioning critical after induction, can give small doses of phenylephrine (20-100 mcg), give bolus before getting started (15-20 cc/kg)
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Wet tap
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CSF leak, headaches 30-50% of the time
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What does accidental subdural injection cause when trying to place an epidural?
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widespread sensory analgesiaw minimal amt of LA
weak/patchy block delayed onset hypotension after initial rxn faster resolution of block |
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How do you deal with accidental intravascular injection when trying to place an epidural?
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1 LUD
2 airway 3 convulsions 4 observe Fetal HR |
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At a plasma concentration of 10 mcg/mL lidocaine, you can see...
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convulsions
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At a plasma concentration of 14 mcg/mL lidocaine, you can see....
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toxicity (coma, resp and CV arrest coming!)
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Clinical characteristics of epidural block
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slow onset, spread as expected, segmental nature, minimal motor block, hypotension dependant on extent of block
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Clinical characteristics of subdural block
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slow onset
spread is higher than expected, usually see sacral sparing patchy nature minimal motor block hypotension dependent on extent of block |
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Clinical characteristics of spinal block
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rapid onset
spread higher than expected, sacral block present dense nature dense motor block hypotension likely |
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If your block is segmental...
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you can give volume to raise the level of the block
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If your block is patchy, this means (Ex)
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"only numb over left chest"
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Reasons for failed epidural block
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- misplaced catheter (false loss of resistance, can go subdural or give a strange block)
- unilateral block (occurs when pt on one side for long periods of time, occurs w >5 cm in space, can pull catheter back but usually futile to try to fix) - segmental sparing (septa or air) |
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WET TAP
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accidently put epidural needle too far, hole is made in dura, more significant leak of CSF (bc epidural needle much larger than spinal needle), promotes PDPH, occurs 1% of the time
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to avoid a spinal hematoma...
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-1 hour delay between needle placement and heparin admin
-catheter should be removed 1 hour before subsequent heparin dose or 2-4 hrs after last dose -monitor PT -Avoid LMWH |
