Considerations for Epidural & Spinal Anesthesia Flashcards
What is an epidural anesthetic?
injection of a local anesthetic into the epidural
space for spread to the region of the dural cuffs
– Leaks into intravertebral foramen and paravertebral spaces
– Medication spread is diffusion dependent
– Onset is longer
What is the idea behind epidural/spinal anesthesia?
Reversible chemical blockade of neuronal transmission
What lasts longer, epidural or spinal?
epidural
What is interrupted with administration of an epidural or spinal?
autonomic, sensory and
motor nerve fiber transmission
[EPIDURAL} results are related to drug concentration & volume
Results of an epidural is related to?
drug concentration & volume
What are 2 major differences between a spinal and epidural?
- Spinal directly bathes spinal cord in local anesthetic
- Epidural is titratable & can be redosed
[spinal catheter CAN be placed but it is RARE!]
What are 2 other names for a spinal?
- subarachnoid block
2. intrathecal block
What are 6 advantages of an epidural?
- ↓ surgical stress
- ↓ opioid consumption
- ↓ overall blood loss
- ↓ risk of DVT
- provides anesthesia OR analgesia (can re-dose, or convert from pain to primary anesthetic in laboring mother)
- versatile
- can use with or without adjunctive medications
- can control extent of sensory or motor blockade based on concentration of local anesthetic used
What are 4 disadvantages of an epidural?
- post dural puncture headache (PDPH)
- sympathetic blockade occurs 100% of the time
- block may last longer than the procedure
- urinary retention
What is more difficult, an epidural or spinal?
epidural
What are considerations when deciding to do an epidural?
- length of surgery
- multimodal pain management
- procedure
[involving abdomen, lower extremities] - certain comorbidities
[pulmonary disease; will keep the pt breathing, no GA necessary]
What are 5 absolute contraindications to an epidural?
- pt refusal
- increased ICP
- severe aortic or mitral valve stenosis
- severe hypovolemia
- infection at injection site
What are relative contraindications for an epidural?
7
1. Uncooperative patient • Inability to communicate / obtain informed consent • Unable to assist 2. Local anesthetic allergy 3. Patient on anticoagulant or thrombolytic therapy [why are they on it? afib, DVT?] --- this might be why doing an epidural is GOOD for them... 4. Preexisting neurologic deficit 5. Chronic headache or backache 6. Severe spinal deformity 7. Valvular stenosis
Pre-procedure medications for epidural placement?
- anxiolytic, do not over sedate!
- follow NPO guidelines
- consider IV bolus if pt is dehydrated?
Minimum pre-procedure monitoring for epidural placement?
- IV
- Suction
- Airway supplies
- ECG, BP, SpO2,
- oxygen
What should be available when performing an epidural?
- suction
- airway supplies
- supportive medications [induction agent, paralytic, atropine, vasoactive meds, zofran]
What type of regional anesthesia is high volume?
epidural
What are the 2 needle approaches for spinal/epidurals?
- midline
2. paramedian
What vertebral body aligns with the lower scapula tip?
T7
What vertebral body aligns with the end of an adult spinal cord?
L1
What vertebral body aligns with superior iliac crests?
L4
What vertebral body aligns with the posterior superior iliac spines? (dimples)
S2
What movement of the spine will create larger interspinous spaces?
flexion
What do you check right before performing an epidural?
- patent IV
- monitoring devices
- oxygen attached & functioning
- resuscitation equipment is available
What are characteristics of a Tuohy needle?
- pronounced curve
- easier for novice
- directional placement of catheter
What are characteristics of a crawford needle?
- not curved
- easier to insert
- higher rate of dural puncture
How long is a standard epidural needle?
9cm
What are 2 factors that alter distance to the ligamentum flavum?
- body habitus
2. level of placement
What is the standard depth of the epidural space in the lumbar region?
5cm
What type of needle requires an introducer?
spinal needle
How is the bevel situated when doing a spinal or epidural?
bevel “up” towards patient’s head
What is the needle advanced through when placing an epidural?
- skin
- SQ tissue
- supraspinous ligament
- interspinous ligament
- ligamentum flavum
- epidural space!
How is the needle inserted/advanced when placing an epidural?
VERY SLOW!! mm BY mm!!
tap plunger of syringe between movements
TAP EVERY mm!!!
If using the “loss of resistance” technique for epidural placement, how much NS or air is in the syringe?
2-3mL
What are you waiting for when advancing an epidural needle?
loss of resistance
How does an epidural catheter compare to the epidural needle?
the catheter is 2 gauge sizes smaller
Dashed lines on an epidural catheter represent, what?
1cm
Two dashed lines on an epidural catheter represent, what?
10cm
Two thick lines on an epidural catheter represent, what?
12cm
What is the distance from the hub of the epidural needle to the tip?
12cm
How far should the epidural catheter be left in the epidural space?
3-5cm
What can happen if the epidural catheter is left inserted too deep?
- puncture of the dura
- passage into epidural veins
- migration through intervertebral foramen
What must be remembered when manipulating the epidural catheter and needle?
NEVER attempt to withdrawal the catheter through the needle
-catheter can break & shear, leaving pieces in the patient!
After placement of an epidural catheter, the needle is removed, then what?
attach adapter to free end, look for blood or CSF, gently aspirate
After attaching the adapter to the epidural catheter, looking for blood or CSF, and gently aspirating, what next?
administer test dose
1.5% lidocaine with 1:200000 epi
What medication is used as the test dose for an epidural?
- 5% Lidocaine
1: 200,000 epi
total: 3mL = 45mg lidocaine with 15mcg epi
How will you know if the epidural is in place?
3mL test dose will cause profound spiral block
OR
HR/BP will ↑ more than 20% if the test dose is administered into the vasculature
What must be remembered before giving an epidural “test dose”?
- ask patient, are you about to have/are having a contraction?
- tell me if you hear ringing in your ears, taste metal, or feel your bottom get heavy
What will happen if your epidural test dose is administered as a spinal?
heavy SADDLE BLOCK within 30 seconds
When is the paramedian epidural approach useful?
when the patient cannot flex their spine. [Hx spinal surgery, rheumatoid arthritis, hip or upper leg trauma]
Where is the skin wheal placed when performing a paramedian approach?
1cm lateral and 1cm caudal to spinous process
When using a paramedian approach for epidural placement, what does the needle advance through?
- skin
- SQ
- paraspinous muscles
- ligamentum flavum
(does NOT pass through supraspinous or interspinous ligaments
What do you do if a patient reports paresthesia?
stop moving, ask if it stops
if the paresthesia goes away, continue
if paresthesia does not stop, remove needle & catheter together and restart at interspinous space above
How do you redirect the epidural needle after hitting bone?
pull the needle and stylet back into SQ fat, reposition the introducer then reinsert the needle
What do you do if you get blood in the epidural needle?
withdrawal the needle & catheter and replace
What are 3 indications of caudal anesthesia?
- hemorrhoidectomy
- chronic pain patients
- pediatric analgesia (inguinal herniorrhaphy, circumcision, perineal procedures)
How is a patient positioned for a caudal block?
- prone on a flexed table or with a pillow under pelvis, legs spread and externally rotated
- laterally
What is the dose of a caudal block?
- 5-1mL/kg
- varying LA concentrations
2.5mg/kg
When doing a caudal block, ensure you are not in which two spaces?
bone
subcutaneous
What is the volume for adult caudal sacral anesthesia?
12-15mL
What is the volume for adult caudal lower extremity block
20-30mL
What are 3 complications of adult caudal anesthesia?
- high failure rate (false passage)
- inadvertent IV injection or catheter placement
- dural puncture
What are the two types of combined spinal epidural?
- 2 level; spinal placed then epidural catheter placed 1-2 levels above
- 1 level; placement of epidural needle, spinal needle is passed through & small intrathecal dose injected, then epidural catheter placed through epidural needle
What are concerns of combined spinal epidural in the partruient?
- intrathecal opioid effects on fetus
- inability to ambulate after receiving narcotics
- maternal hypotension & itching
What are 6 potential complications of combined spinal epidural?
- failure to obtain either block
- catheter migration
- increased spinal level
- metallic particles
- PDPH
- neurologic injury
What 2 things does neuraxial imaging facilitate in spinal/epidural placement?
- identify interspaces
2. determine depth to epidural space
How much metabolism of local anesthetics occurs in the CSF?
little to no
What does added vasopressor do to local anesthetics?
slows absorption and prolongs block
What are 3 ester local anesthetics?
- procaine
- Chloroprocaine
- Tetracaine
What are 4 amide local anesthetics?
- lidocaine
- mepivacaine
- ropivacaine
- bupivacaine
What is the onset & duration of procaine?
slow / 60-90m
What is the onset & duration of Chloroprocaine?
Fast 30-60m
What is the onset & duration of tetracaine?
slow / 180-600m