Regional - Exam 2 Flashcards
ABSOLUTE contraindications for CNB
-pt refuses #1
-coagulopathy or bleeding diathesis
-increased ICP
-severe aortic or mitral stenosis
-ichemic hypertrophic subaortic stenosis
-allergy
-hypovolemia
-infection at injection site
-timing
Relative contraindications for CNB
-coagulopathies
-sepsis
C Spine nerves emerge _ the respective vertebrae
above
-UNTIL C8, EMERGES BELOW CV 7
All spinal nerves beyond the cervical region emerge _ the respective vertebra
below
DC AC for neuraxial block?
-ASA or NSAIDS
no restrictions, safe w neuraxial blocks
DC AC for neuraxial block?
-clopidogrel (plavix)***
DC 5-7 days prior **
DC AC for neuraxial block?
-warfarin (coumadin)
DC 4-6(or 5) days WITH normal INR*** ( N= 1.0, therapeutic for AC=2-3)
Spinal anesthesia is AKA : (3 other names)
subarachnoid, intrathecal, SAB
Spinal anesthesia is a temporary interruption of nerve transmission in _ space produced by LA injection into _.
subarachnoid
CSF
T/F Spinal blocks can be used in wide variety of settings and can allow segmental control of which parts are blocked.
F, not as broad as epidural, all or nothing, total sensorimotor block
T/F epidurals can deliver LA via a single bolus, continuous infusion, titratable, or via PCA for postop pain
true
-can allow for segmental blocks
Which method of neuraxial block is diffusion dependent?
epidural
-requiring larger volumes than spinal
Typical LA volume required for a spinal block is _-_mL and for epidurals is _mL
spinal: 1-4mL
epidural: 20mL
_ blocks can take longer to achieve and longer to perform.
epidural
_ blocks can be given anywhere on spinal column unlike _ blocks which must be below spinal cord under L2
epidural
spinal
Which method of neuraxial block has a lower risk of PDPH and hypotension, spinal or epidural?
epidural
The spinal cord extends from the _ _ to the spinal level _ or _ (adults) and _ in kids
foramen magnum
L1/L2
L3
The dural sac can be found in adults at _ and kids at _
S2
S3
The epidural space is between the _ _ and _
vertebral canal and meninges
The dura extends from the _ _ to _ and terminates as the _ _
foramen magnum to S2
filum terminale
Which meningeal layer adheres to the spinal cord?
pia mater
Which area of the spinal cord contains CSF?
subarachnoid space
T/F the dural sac is the highest point one may give a spinal block
false, dural sack is at S2, spinal must stay below L2
T/F A spinal block can be placed at L1 or above
false!
must be BELOW L2
The vertebral column extends in midline from the _ of the _ to the pelvis
base of skull
T/F spinal canal’s functions are supporting head, protecting vertebral column, attaching point for extremities, and transmission of weight from trunk to LE
false, this is the job of the vertebral column
**The landmark which is the most prominent spinal process is _ which has the spinal segment _ beneath it. **
CV7, C8
* The landmark that is opposite to the inferior angle of the scapula is _*
T7
Tuffier’s line is a landmark connecting the iliac crests which is at the level of _ - _
L4-L5
-IMPORTANT FOR SPINALS
How many fused bones are there in vertebrae?
- 5 sacral
4 coccyx
How many total vertebrae are there? In which regions?
33 total
7 C
12 T
5 L
5 S
4 C
***The caudal end of the epidural space can be accessed via the _ _
sacral hiatus
-an opening formed by incomplete POSTERIOR fusion of FIFTH sacral vertebrae***
-important landmark for caudal anesthesia
The cervical and lumbar curves are _ anteriorly and _ posteriorly
convex
concave
The thoracic and sacral curves are _ anteriorly and _ posteriorly
concave
convex
What significance does anatomical curves of vertebral column offer?
influences spread of LA in SUBARACHNOID space along with gravity and baricity of LA
If pt laying supine, which points are high points? ***
C5 and L5
High 5!
If pt laying supine, which points are low points? ***
T5 and S2
When going thru low point ppl say “Thats 5ad”, and “Sorry” 2
The spinal canal extends from the _ _ to the _ _
foramen magnum
sacral hiatus
Contents of the spinal CANAL
-spinal cord
-spinal nerves
-epidural space
***Boundaries of spinal CANAL:
Ant: vertebral body*
Lat: pedicles*
Post: spinous processes and LAMINAE*
-help guide placement of needle for neuraxial techniques ***
Which articulate posterior elements of adjacent vertebrae?
Vertebral facet (zygapophyseal) joints
The _ articular process protrudes caudally and overlaps the inferiorly adjacent vertebra’s _articular process
inferior
superior
The junction of the lamina and pedicles gives rise to
inferior and superior articular processes
Which ligaments reinforce the vertebral column anterior and posteriorly?
Ant and Post LONGITUDINAL ligaments
**Give the order of structures the needle will pass before it reaches the subarachnoid space for a spinal block:
1.skin
2. subcut tissue
3. supraspinous lig
4. interspinous lig
5. LF
6. epidural space (STOP IF EPIDURAL*)
7. dura
8. arachnoid
Which ligament connects the apices of the spinous processes?**
supraspinous
The supraspinous lig is strong and fibrous, connects the spinous processes from the _ to _**
sacrum to C7
Which ligament is a thin membranous and connects spinous processes?**
infraspinous lig
-supraspinous connects this via apices and is strong and fibrous
Which ligament has a DENSE supply of yellow elastin fibers?
LF
Which ligament will give a sense of resistance to one placing a neuraxial needle?***
lig flav
***The spinal CORD spans:
CONTINUOUS above medulla oblongata and extends to lumbar region as CONUS MEDULLARIS**~LV1/LV2
**The landmark which is the posterior superior iliac spine is found at level. **
S2 and S3
Cauda equina is where we typically place _ blocks.
spinal
-bundle of nerve roots in the SUBARACHNOID space past conus medullaris
-covered in PIA mater so sensitive to LA**not dura like other parts
Nerves exit the _ _ which is between pedicles of 2 adjacent vertebrae
intervertebral foramen
***How many spinal nerves are there?
62!! 31 PAIR***
-8C
-12T
-5L
-5S
-1C
Target sites of neuraxia anesthesia?
spinal nerve roots and spinal cord
Dura mater is tough, fibrous and INelastic and extends from the _ _ to the _ (S2)
cranial vault
sacrum
Which meninge is thin, vascular, fibroelastic tissue and terminates at filum terminale?
PIA
The epidural space extends from the _ _ to the _ _
foramen magnum
sacral hiatus
The epidural space produces negative pressure of _ cmH2O with inspiration
-9cm H2O
***Contents of epidural space:
-nerves
-vessels (arteries and vertebral venous plexus AKA BATSON veins)
-fat
-lymphatics
-connective tissue
Skin to epidural space distance ranges from 2-9cm but is TYPICALLY:
4cm
*** Contents of subarachnoid space:
-numerous arachnoid trabeculae-spongy masses
-spinal cord
-nerves
-CSF
-blood vessels
*Blood supply of the spinal cords comes from _ anterior and _ posterior arteries
1
2
T/F A benefit of having neuraxial anesthesia only is pts do not need to fast
false, yeah they do!
-less risk of N/V can still happen tho
Optimal cases for neuraxial anesthesia:
-cases of perineum, lower abdomen, and LE
-laboring pt -> CS
-**TURP to monitor for TURP syndrome
-upper abdominal surg
-cholecystectomy or gastrectomy
Primary site of action of neuraxial anesthesia is _ _ and the secondary is the _ _
nerve roots
spinal cord
*Factors influencing sensitivity of nerve fiber to LA:
-anatomical position(location or number of axons)
-chemical factors(myelination-more sensitive)
*Factors influencing onset, duration, and differential blockade of different functions of body:
-which fiber is blocked
-which LA is being used
-both affect DIFFERENTIAL sensitivity
Physiological causes of differential blockade:
-distance AND type of nerve fibers relative to the injection site (diffusion causes spread and less LA available the farther the spread)
If giving a spinal block at L3/L4, expect a sympathetic block to be about _ dermatomes beyond motor block, and pain/touch sensory block to be about _ dermatomes from motor block
2-4 dermatomes
2-3 dermatomes
SENSORY BLOCK WILL BE 2 ABOVE MOTOR
SYMPATHETIC BLOCK WILL BE 2 ABOVE SENSORY
Why could B fibers be the easiest to be affected by neuraxial blocks and cause sympathectomy?
-lightly myelinated, small in size, usually found on outside of nerves
Neuraxial fiber block order:
-B (pre ganglionic- autonomic**)
-A Delta + C fibers (C>A deltapost ganglionic-pain/temp/touch)
-rest of A fibers (gamma>beta>alpha-proprioception +motor)
B>C>Ad>AG>Ab>Aa
Neuraxial fiber recovery order occurs in _.
reverse
-motor/proprioception function comes back 1st
-A alpha>beta>gamma
-A delta > C
-B
***Neuraxial sensorimotor function block order:
- sympathetic function
- pain
- temp, touch, pressure
- proprioception
- motor function
Spinal block distribution is dependent on:
-Baricity
-Pt position (except isobaric)
-Dose(concentration) of LA
Giving a spinal block for perineal/anal procedures should have block around -
S2-S5
-saddle block
Giving a spinal block for foot and ankle procedures should have block at_
L2
Giving a spinal block for thigh/LE procedures should have block at _
L1
Giving a block for TURP, vaginal delivery, or hip procedures should have block at _
T10
TURP T10
Giving a block for LE (with tourn) procedures should have block at _
T8
Tourn T8
Giving a block for intestinal, GYN, or urology cases should have block at _
T6
inTestinal
Giving a block for abdominal procedures should have block at _
T4
T4 block correlates with
nipple line
T6-T7 block correlates with
xiphoid process
T10 block correlates with
umbilicus
L1 block correlates with
inguinal ligament
C8 block correlates with
fingers
Hyperbaric LA is _ dense than CSF and spreads _ more easily.
more
up
How to make more dermatomes anesthetized with neuraxial block:
increase dose
How to keep dermatomes anesthetized longer with neuraxial block:
add Epi to LA
-increases DOA
Shortest acting LA
lidocaine
Longer acting LA
Tetracaine
Which LA is isobaric?
Mepivacaine
Serum conc of LA depends on:
injection technique
site of injection
additives
Bupivicaine max dose
3mg/kg
Lidocaine max dose
4.5mg/kg
7mg/kg with Epi
Mepivacaine max dose
4.5mg/kg
7mg/kg with Epi
Prilocaine max dose
8mg/kg
Ropivacaine max dose
3mg/kg
Rop = 3 letters
T/F Adding opioids increases sensorimotor block in spinal blocks
false, just sensory only
Adding fentanyl to spinal LA
-dose
15-25mcg
Adding morphine to spinal LA
-dose
0.1-0.5mg
-up to 1mg
Spinal anesthesia can cause CV changes via blocking the _ _
sympathetic chain (preganglionic)
-B fiber ae easiest to block, higher the block, higher level of sympathectomy
MOA of CV effects after spinal block:
causes venous dilation leading to
-reduced preload and HR, SVR (results in reduced CO)too
-venous system depends on gravity for return, position/pt wt plays role in this too
Tx for CV effects after LA spinal block:
give fluids (preferably before this happens) or epi if absolutely needed
-know how to calc maintenance fluids
N/V from spinal block is probably due to chemical sympathectomy with unopposed _ tone and/or hypotension
parasympathetic tone
-give fluids, treat for hypotension
If a pt is tachycardic after spinal block, it is likely due to _ _ with hypotension
baroreceptor rrflex
If a pt is bradycardic this could be from a sympathetic block on cardiac _ _ which are found on T1-T4**
accelerator fibers
-SLOW onset
-treat with epi and ephedrine
Main causes of hypotension following a spinal block:
decreased CO from decreased preload and/ or hypovolemia
Mgmt of hypotension from spinal:
-monitor VS
-Tx BP (healthy pt >33% drop, CV pt >20-25% drop)
-watch ST segment
-give supp O2
Mgmt of hypotension from spinal:
-fix BP
Restore preload
-crystalloid/colloids 500-1500mL(won’t help much if pt euvolemic)
-Trend bed
-displace uterus
-pressors
Mgmt of hypotension from spinal:
-pressors
Ephedrine (DOC)
-5-15mg IV
Phenylephrine
-50-100mcg IV
Epi
-5mcg IV
Spinal block impact on CBF
can disrupt autoregulation if hypotensive
-keep MAP >50-55mmHg
T/F CBF autoregulation is directly influenced by SNS
false
Spinal block influence on renal f’n:
changes are proportional to changes in arterial BP
-GFR can decrease if blood flow decreases
Spinal block into thoracic region can affect _ and _ muscles, leading healthy pt to think theyre not breathing
intercostal and abdominal
-if pt talking and spo2 ok theyre fine
GI effects from spinal block:
continued peristalsis from contracted gut and relaxed sphincters, good for GI surgeon
The PNS of the gut doesn’t get blocked because the _ nerve doesn’t get blocked by neuraxial spinal block allowing for continued peristalsis
vagus
Spinal blocks are performed below the level of _ and use Tuffier’s Line as a landmark which is seen at -.
L2
L4-L5
Should feel a “pop” after going thru _ with needle
LF
Needles with gauges larger than _ G don’t need an introducer
22G
The _ needle has highest rate of PDPH bc its used for spinals and cutting
Quincke
Check BP Q - min with spinals
3-5 min
During a spinal, aspirating approx _ mL of CSF tell you you’re in the _ region
0.2ml
subarachnoid
When using Quincke needle, move bevel to face _ to avoid cutting dura
hip
***Midline approach- spinal
midline
lower 1/3 of interspace
slightly cephalad direction (10* angle)
Benefit of Paramedian approach for spinals
can use it to avoid calcified ligaments or work around when pt anatomy is difficult (kyphosis)
-thoracic epidural insertion bc steepness of spin processes
Epidurals, compared to spinals have an increased risk of _ but lower risk of _
LAST (b/c Batsons veins are closeby)
PDPH
Epidural LA MOA:
spinal roots in CSF (subarachnoid space)*, mixed nerves in epidural space and spinal cord via DIFFUSION
Granulations in the _ mater increase the rate of diffusion in epidural blocks
dura
Epidural site of action:
-spinal nerve roots**
-rootlets
-mixed spinal nerves
-DRG?
-SC
-Brain (bc impulses won’t conduct via SC)
Main factors impacting level of epidural block:
-dose (concentration AND volume); more volume, more vertical spread
-injection site (and rate)
-NOT baricity
The ideal anesthetic insertion point for epidurals is at the _ level
surgical
Lumbar epidural blocks tend to have a greater cranial than caudal spread bc there’s a delay at _ - _ and these nerves are larger and harder to block
L5-S1
T/F Lumbar blocks are more evenly spread than midthoracic blocks for epidurals
false
The _ needle is used for epidural blocks and the average appropriate depth is _-_cm
Tuohy (idk how to spell lol)
4-6cm
The Tuohy (spelling?) needle has markings that are _ cm increments and is _ cm from tip to prox hub and _ cm from tip to distal hub
1cm
9cm
11cm
Once placed properly, the epidural catheter should be thread _-_cm into pt beyond needle tip.
3-5cm
-so if 4cm in pt with needle, thread just past 9cm and pull back until 9cm
For cervical and lumbar epidural blocks, approach should be _ while thoracic should be _ due to the steepness of SPINOUS PROCESSES
MIDLINE
PARAMEDIAN
With paramedian epidural approach, use anatomic landmarks to plan insertion and _ to redirect when necessary
bone
-usually thoracic vertebra LAMINA
Epidural insertion site
-mastectomy
T1
Epidural insertion site
-thoracotomy
T4
Epidural insertion site
upper abd
T7-T8
Epidural insertion site
-lower abd
T10
Epidural insertion site
above knee LE
L1-L2
Epidural insertion site
below knee LE
L3-L4
Epidural insertion site
Perineal
L4-L5
Tuohy needle is - G and rounded at the tip to prevent crossing thru _
17-18G
dura
-keep bevel UP
In epidural placement after loss of resistance technique, if unable to thread catheter, what do you do?**
-add 1mL NS to open space to thread cath
-if still unable to, WRONG SPOT, try again using same puncture site
LF is _-_mm thick
5-6mm
T/F aspirating is only necessary with spinals bc epidural space doesn’t have CSF***
false, while epidural space doesn’t have CSF, if it is aspirated, you know you’ve gone too far (thru dura) and if heme is aspirated you’re at risk for injecting into vasculature
T/F negative aspiration of CSF or blood means you’re in the epidural space and you’re gtg
FALSE!
-could be up against tissue in WRONG spot, ok to inject sm amt of NS to “flush”
-TEST DOSE negativity is the ticket
The test dose for epidurals consists of_ mL of _ % Lidocaine and 1: _ of Epi
3mL
1.5%
1:200,000
= 45mg Lido + 15mcg Epi
T/F a test dose should be given for ALL epidural blocks regardless of location
false-don’t give if >T10 block
Test doses for epidurals, if given in wrong spot can cause:
-sensory block in 3-5 min
-15-20 bpm increase in HR for 2-3 min (may not be seen in old pt, OB, or those on BBs)
-if + REMOVE
T/F must aspirate before every injection
true!
T/F dose, site, and baricity effect spread of all neuraxial LA
false,
epidural spread doesn’t depend on baricity and depends more on volume than concentration unlike spinals
Bupi <0.25% epidurak will cause a
sympathectomy
Bupi 0.5% epidural can cause
dense sensory block
mild motor block
Bupi 0.75% epidural can cause
full anesthetic block (sympath + full sensorimotor)
***Typically want to give - mL of epidural LA per dermatome segment you’re trying to block (while considering it spreads vertically)
1-2mL
**If giving epidural at T12-L1 and need coverage up to T8, how many mL of LA do you give?
~5 dermatomes
so 5-10mL **
Adding Bicarb to LA epidural does what?
raises pH and increases rate of diffusion /speed of onset
-alkalization speeds onset for LA
If adding bicarb to LA epidural, how much should be added?
1mL of 8.4% Na Bicarb to 9mL of LA
High spinal carries respiratory risk bc
paralysis of accessory muscles, weak cough, unable to ventilate or protect airway
Urine rtn/ poor bladder tone can happen from a _ blockade of S2-S4
sympathetic
**PDPH ppl at risk:
-female
-preg
-younger
PDPH s/s
-positional HA(frontal, occipital, radiating to neck, better laying flat or with abd pressure)
-N/V
-less often: ocular and auditory s/s
PDPH tx
-pvn
-supine (bedrest compresses CSF leak)
-fluids
-pain meds
-CAFFEINE
-EPIDURAL BLOOD PATCH (10-20mL)
T/F Epidural hematoma and abscess have same symptoms
true
-ACUTE back pain and/ or sensory and motor deficits PROGRESS to paraplegia and INCONTINENCE*** (12hr-2days postop)
-dx: MRI
-tx: surg decompress w/in 8hr
High/ total spinal
-s/s
-severe hypotension
-bradycardia
-resp distress (rapidly changes to apnea)**
-from high spread of LA on SC and brainstem
High/ Total Spinal
-tx
supportive
-airway: vent + O2
-CV: pressors and fluids (atropine for brady or ephedrine or epi for both brady and low BP)
Bladder + bowel dysfunction and leg weakness after receiving lidocaine 5% is most likely what syndrome?
cauda equina syndrome
LAST
-factors influencing plasma conc.
-dose
-rate absorbed
-site injected/ use of adjuncts
-biotransformation or elimination of drug
LAST
-early s/s
CAN BE MASKED IF PREMEDICATED W BENZO
-dizzy
-tongue numb*
-difficulty focusing
-tinnitis**
-confusion
-muscle twitching
LAST
-late s/s
-ton/clon sx
-coma
-resp + cardiac arrest
LA are myocardium depressants
-arrhythmias seen:
-conduction delays (long PR, CHB, asystole)
-stubborn ventricular dysrhythmias (despite traditional therapies)
LA are myocardium depressants
-low blood levels LA cause
-small INCREASE in CO, BP, HR from SNS activity and VASOCONSTRICTION
LA are myocardium depressants
-high blood level of LA cause
-low BP from low PVR, low CO, and arrhymias
-arrest
LAST
-pvn
-US GUIDANCE
-benzos as premedication can lower seizure rate but mask s/s
-be ready for anything
-LA and resusc drugs close by
-double check dose(give LOWEST effective dose)
-deliver in increments (3-5ml w/ 15-30s pause between)
-aspirate Q injection!
-TEST DOSE! (45mg Lido 15mcg Epi!)
-VERBAL communication w pt
LAST
-Tx, resp
O2-mask, LMA, ETT
LAST
-Tx CV/meds
-lift legs, fluids, BP meds
-anticonvulsants (benzos, prop, thiopental)
-standard arrhythmia drugs (EXCEPT CCB, sodium valproate, phenytoin, vasopressin, and other LAs)
LAST
-lipid infusion
-if pt unresponsive to standard resusc. but can give immediately after securing airway*
-bolus
-infusion
-CHEST COMPRESSIONS TO CIRCULATE
-repeat bolus Q 3-5 up to 3mg/kg
-leave infusion on until CV stable
Intralipid bolus dose
Pt <70kg :
1.5mL/kg (IBW) over 2-3min
repeat bolus x3 for persistent CV collapse; upper limit 12mL/kg in 1st 30 min
Pt >70kg
20% Interlipid
100mL over 2-3 min
Intralipid infusion
Pt<70kg:
0.25-0.5mL/kg /min
Pt >70kg:
200-250mL over 10-20 min
-keep on for at leas t10 min after CV stable
LA toxicity requires close control on what factor due to the factor’s influence on inotropic/chronotropic effects?
O2 + ventilation
-hypoxia, acidosis, and hypercarbia worsen this
LAST
-TEST DOSE concentrations and actual dose
3mL of 1.5% Lidocaine + 1:200,000 Epi
= 45mg Lido + 15mcg Epi
How long to hold coumadin for during regional case?
5 days
Which risk factors for development of post dural puncture headache are correct? Pick 2:
a. Elderly
b. female
c. pregnant
d. short
c+ d, female + pregnant
Which is the last ligament a needle passes thru when giving an epidural?
LF
During a spinal, which needle type is most likely to cause post dural puncture headache?
Quincke
What structure “pops” during a subarachnoid block when done properly?
LF
MOA of LA injection into epidural space:
-distributes along epidural space
-retained in fatty tissue
-diffuses thru dural cuffs
A Quincke or Whitacre can be used for a _ block
spinal
Baricity and positioning affect _ blocks
spinal
A/an _ block can be given at cervical, thoracic, or lumbar levels.
epidural
The onset of _ blocks are 10-20 min
epidural
The _ block gives segmental anesthesia
epidural
After placing a spinal block, your pt is bradycardic 10 mins later. This means their block level went up to _ - _.
T1-T4
If you want a spinal block to move cephalad, mix _ _ with the LA.
sterile water
-not dextrose or CSF
Your pt complains of rapid HR and ringing in the ears after a successful test dose and epidural is placed. What should you do?
remove the epidural cath asap
