Week 3 Regional - Epidural Everything Flashcards
Central neuraxial blockade (CNB)-
spinal and epidural blocks (involve placement of LA onto or adjacent to the spinal cord
Central neuraxial blockades are used for a variety of reasons. Name some:
-surgical procedures, -treatment of acute and chronic pain syndromes, -labor analgesia-safe transition if C/S required -May be used in combination with other types of anesthesia (MAC, GA etc..for surgery) -Post-op pain relief
CNB’s are a Surgeon preference due to:
- procedure (urologic procedures, can monitor neuro status etc..)
Incidence rate of persistent paresthesia and sensory or motor dysfunction is
< 1%
Discussion with patient alleviates most:
fear/concern
Additional discussion with patients include talking about topics such as:
risks, inadequate anesthesia, additional medications, paresthesia, hypotension, dyspnea, high or total spinal, N/V, and allergic reaction …
CNB Postoperative complications:
backache, postdural puncture headache (PDPH), hearing loss, transient neurologic symptoms (TNS), infection, abscess, or hematoma formation
Absolute vs relative contraindications- somewhat controversial
-Increased intracranial pressure (ICP) -Skin infection at site of injection -Bacteremia/sepsis/shock -Hypovolemia -Spinal cord disease -Progressive neurological diseases (MS, etc) -hypertrophic cardiomyopathy or -severe aortic stenosis) -Coagulopathy. -“anticipated” length of surgery
what are transient neruologic symptoms (TNS) *from his notes
TNS is a painful condition of the buttocks and thighs with possible radiation to the lower extermities, beginning as soon as a few hours after spinal anesthesia and lasting as long as ten days. Pain can be mild to severe. However, unlike in cauda equina syndrome, TNS is exclusively a pain syndrome - there is no bowel or bladder dysfunction, and neurologic, MRI , and electrophysiologic examinations are normal.
what is Cauda equina syndrome (CES)? ffrom his notes
Cauda equina syndrome (CES) is a serious neurologic condition in which damage to the cauda equina causes acute loss of function of the lumbar plexus, (nerve roots) of the spinal canal below the termination (conus medullaris) of the spinal cord. CES is a lower motor neuron lesion
why is ICP contraindication for spinal/epidural?
Increased ICP- spinal/epidural increases risk of brain herniation if dura is punctures… also, addition of large volume of fluid into epidural or SA space could increase already elevated ICP
What are some anatomical concerns that may have you NOT place an epidural or a spinal?
Severe kyphoscoliosis arthritis ( -kyphosis and scoliosis), -osteoporosis-vertebral deformities and -fractures with narrowing of the spinal canal, -lumbar fusion (may make placement difficult)
Coagulation contraindications (2:
Controversial range.. 1. Plt < 100,000 2. PT, PTT and bleeding times greater than 2 times the normal values Assess herbal medications that may affect hemostasis (garlic, ginkgo, ginseng)
what herbal medications should we Assess for and why?
- that may affect hemostasis -garlic, -ginkgo, -ginseng “anything with a “G”’
Regional thrombophrophylaxis: Contraindication or not? When to stop/Restart before/after block. ASA or NSAIDs
no contraindication
d/c ticlid prior to block
14 days
d/c plavix prior to block
7 days
GP 11b/111a inhibitors (Aggrastat, Integrilin) d/c prior to block
8 hours
ReoPro d/c
24-48 hours
Heparin- Subcutaneous is it contraindicated in regional techniques?
No contraindication in BID dosing of < 10,000 units
Regional thrombophrophylaxis: Heparin-IV Contraindication or not? When to stop/Restart before/after block.
…Heparinize 1 hour after block, -remove catheter 2-4 hours after last dose
LMWH (lovenox) plan for regional
-delay procedure at least 12-24 hours after last dose… -remove catheter 2 hours before first dose
Warfarin- usually requires d/c
for 4-5 days before Because:block requires normal INR.. Remove catheter when INR is 1.5 or less)
block requires
normal INR..
Thrombolytics (Retavase etc..)-
Absolute contraindication
Thrombin inhibitors-Angiomax
Avoid block insufficient info..
ASRA Guidelines
will add
Mini Dose heparin SQ prophylaxis is
not a contraindication to neuraxial anesthesia or epidural catheter removal
If a patient is to receive heparin intraoperatively, blocks may be performed
1 hour or more before heparin administration
IV Heparin stop _____ (hours) prior to catheter removal.
2-4 hours
IV Heparin – Wait _____ after neuraxial block or catheter removal before administration of drug
1 hour
Pradaxa- d/c
7 days prior to regional block;
Pradaxa first post-op dose (after needle placement and after catheter removal)
-24 hours after needle placement and -6 hours post catheter removal (whichever is later)
Herbal meds-
no evidence for d/c.. Be aware of drug interactions etc..
Infection (regional related) can cause persistent
neurologic deficit… -loss of bowel and bladder control, -chronic pain, -lower extremity paraplegia
Sources of Infectious complications:
-Abscess (epidural, spinal, or subdural; paravertebral, paraspinous) -Meningitis -Encephalitis -Sepsis -Bacteremia, fungemia, or viremia -Osteomyelitis -discitis
Ways we can limit infection in regional techniques:
-WBC -Use sterile technique -Use of sterile occlusive dressing at catheter insertion site -Use of bacterial filter during continuous infusion -Limit disconnection and reconnection of delivery system -Limit duration of catheterization
most common cause of epidural abscess
Staphylococcus aureus –
is there a set limit on WBC’s for when we won’t perform regional techniques?
No
When assessing WBCs what do you want to look at specifically?
neutrophils - associated with early infection/reaction
Advantages of Spinal anesthesia include:
-Reduced stress response to surgery -Less blood loss (hip surgery) -Less incidence of DVT -Pulmonary complications appear to be less -Possible less cardiac complications -Better in obstetrics —> less medications are administered to mother and fetus
What equipment do you want for spinal anesthesia?
**Always have your emergency equipment ready** -as well as equipment for block (kit, needles, syringes, solutions, meds, drapes, 4x4s, gloves, etc *FLUIDS
goal of needle design is to
minimally rend, tear, or cut dural tissues
2 main types of needles:
- Quincke-Babcock (or Pitkin ) 2. Whitacre, Sprotte, (Pencan)
describe Quincke-Babcock or Pitkin needles–
have cutting bevel tip with matching stylets that minimize tissue coring, and the tips cutting angle is blunter than that of standard needle
describe Whitacre, Sprotte, Pencan-
newer noncutting tip that are pencil point shaped with lateral opening (other new noncutting needles may have rounded bevel tip and an opening at the needles end)
gauges for spinal needles:
22-29 g
lengths for spinal needles:
3.5 and 5 inches
Most blocks are performed using a
25-27 gauge, 3.5 in needle
What needle is preferred? why?
Noncutting (pencil point/Whitacre/Sprotte) -less of incidence of complications such as: - infection, -PDPH -also have a clear, perceptible “click” or “pop” when pierce the dura
what needles has a clear, perceptible “click” or “pop” when pierce the dura
non-cutting - whitacre/sprotte/ pencil point
Newer, thin walled noncutting needles have improved
CSF flow rates
Pencil point needles are associated with what % of PDPH? % of failure rate?
<1% rate of PDPH and failure rate of approx. 5%
spinal structures entered (in order):
Skin Subcutaneous structures Supraspinous ligament Interspinous ligament Ligamentum flavum Dura Mater Arachnoid membrane “some say sister ida loves doing acid”
spinal anesthesia is what kind of blockade? this results in:
blockade of sympathetic nervous system (nerve transmission of sensory adn motor fibers) –> hypotension and bradycardia
If block is too high (T1-T4), what happens? why?
cardiac accelerator fibers -severe bradycardia -overall loss of normal CV homeostatic reflexes and ability to compensate for minor CV stresses
what is very important that we do DIRECTLY before block?
fluid bolus - tx hypotension with hydration, O2, meds
spinal cardiac arrest odds vs those of GA
spinal: 7:10,000 GA: 3:10,000
Depression of the cervical spinal cord and brain stem fxn, dysphonia, dyspnea, UE weakness, LOC, mydriasis, hypotension, bradycardia, and cardiac arrest are signs of
Total Spinal
Nausea and vomiting in spinal anesthesia results from:
- unopposed/dominant parasympathetic activity-GI hyperperistalsis… 2. hypotension
increased tone of urethral spinchter results in
urinary retention
paraplegia occurs how frequently?
< 1 per 10,000
PDPH causes - two theories:
- decrease in CSF available in SA space through leak created by dural puncture… medulla and mainstem lose support, drop into foramen magnum, stretch meninges and pull on tentorium… further irritated by movement and upright position 2. cerebrovasodilation as result of low CSF… beneficial effects of vasoconstrictor drugs such as caffeine and theophylline
Causes associated with PDPH
-Large, non-pencil point needles (cutting needles)-Quincke -Multiple punctures -Female patients -Young patients -OB (esp in 30s)
PDPH occurs w/in how many hours postop? resolve in?
several hours -within the 1st or 2nd post op day Resolve in <10 days
in addition to caffeine, what is another cerebral vasoconstrictor/CNS stimulant we might use to tx PDPH?
Theophylline **caffeine dose: 500mg IV
Accessory abdominal and intercostal muscles for ventilation are impaired… ability to cough and clear secretions is inhibited… pts “feel”
dyspneic (creates anxiety, esp in OB pt.. Communicate with pt that this is normal/ reassure the pt)
Careful with sedation after block, somnolence usually occurs for normal, un-medicated patient, those medicated may become
overly sedated (esp with those that were receiving lots of pain meds prior to block
before performing any spinal anesthesia, what all should we do first:
-Obtain consent and perform pre-op exam (PMH/physical exam/labs etc..) -During pre-op, explain procedure, risks/benefits, etc -Obtain necessary equipment (emergency and equipment for block) -Obtain needed medication (emergency and block drugs) -Fluids -Position patient and identify landmarks
before performing any spinal anesthesia, what all should we do first:
-Obtain consent and perform pre-op exam (PMH/physical exam/labs etc..) -During pre-op, explain procedure, risks/benefits, etc -Obtain necessary equipment (emergency and equipment for block) -Obtain needed medication (emergency and block drugs) -Fluids -Position patient and identify landmarks
*** most used interspace is:
L3-L4
*** largest interspace is:
L5-S1
** spinal cord ends at (adults and peds):
L1-L2: adults L3: peds
** Dural sac ends (adults and peds);
S2: Adults S4: peds
*** When performing any neuraxial techniques, what is a vital step we perform PRIOR to injecting medication?
aspirate - looking for CSF, blood, etc. Make sure we are where we should be EVERY TIME
when placing skin wheel, what agent do we use?
1% Lidocaine
in a spinal - when we aspirate, what do we want to see?
+ CSF - (should swirl with fluid in syringe) - blood
what patient types might be well suited for a paramedian approach?
elderly arthritic patients
needle is inserted 1 cm (1 fingerbreadth) lateral to the caudal (posterior) aspect of the interspace… the needle is directed slightly cephalad and then medially approx 10-15 degrees This describes what approach?
Paramedian-
In addition to median and paramedian approaches, what is a less common technique used? differences?
-Taylor Approach (paramedian) -L5 interspace -1cm medial, 1cm caudal to posterior superior iliac spine -needle is directed medially and cephalad at 55 degree angle toward L5
The anesthetic agent is reabsorbed from the CSF into the circulation for metabolism
and elimination
**what is the resting position of 2 fluids with differing specific gravities when the fluids are mixed in a single container (CSF and LA in SA space)?
Baricity
**when the baricity(ratio for specific gravity of LA to patient CSF)=1.. Remain and act in same location injected
Isobaric-
**has a SG > than that of CSF… baricity > 1.0015…soln falls or sinks to lowest anatomic point at which CSF is contained in relation to gravity and pt position
Hyperbaric-
**baricity < 0.999less dense than CSF; soln rises or floats
Hypobaric-
**factors that affect level of spinal anesthetic:
-patient: height, position, gender -Type of needle, site of injection, and the direction of the needle -Dosage amount and choice of LA -Characteristics of the local anesthetic (baricity) -Volume of CSF in the spinal canal
***most influential factor affecting spinal anesthesia:
Dosage
Dermatomes for: Nipple: Xiphoid: Umbilicus:
nipple - T4 xiphoid - T6 Umbilicus - T10
dermatome for c/s:
T4
Duration of spinal depends on:
-LA and total dose -protein binding of drugs (more pr binding, longer DOA; less pr binding, shorter DOA) - Vasocontrictor use (delays uptake of LA)
epi and phenylephrine vasoconstrictor doses:
Epi: 0.1-0.2ml of 1.1000 (1mg/ml) Neo: 2-5mcg
**highly protein bound LAs; longer DOA
Bupivacaine Ropivacaine Tetracaine “BRT” - be right there
** less protein bound LAs; shorter DOA
Lidocaine Mepivacaine
120 – 150 minutes…minimal increase with addition of vasoconstrictor which LA?
Bupivacaine 0.75 %:
90 – 120 minutes, double the time with the addition of vasoconstrictor which LA?
Tetracaine 1%:
short to intermediate 60 – 75 minutes, with added vasoconstrictor possibly 90 minutes (usually epinephrine) which LA?
Lidocaine 5 %:
addition of opioids/clonidine to spinal anesthetics produce synergistic effects, resulting in
prolonged and adequate spinal anesthesia
just for knowledge and exposure opioids added to spinal anesthetics and dosing:
10-25 mcg fentanyl 2.5-10 mcg sufentanil 250 MCG preservative free morphine 20-100 mcg hydromorphone 150 mcg clonidine
Epidural Indications are similar to those of SAB with distinct difference that epidural allows for
continuous anesthesia secondary to placement of catheter
** Epidural LA spread
- horizontally and cephalad (diffuses into CSF & leak into intravertebral foramen and paravertebral spaces to achieve anlagesia/anesthesia)
epidural anesthesia is dependent on:
diffusion
because Epidural anesthesia is diffusion dependent this means?
relatively large volumes of LA must be used (20 mL) for block like SA
advantages of Epidural over GA:
-no airway manipulation needed (alternative for difficult airway etc..) -Less hypertension and tachycardia -Less thrombogenesis -Less postoperative nausea and vomiting -Better post-op pain control -Less pulmonary dysfunction postoperatively -Less blood loss intraoperatively
potential complications of epidural:
-Hypotension (sympathetic blockade) -Intravascular injection of local anesthetic -Subarachnoid injection (high spinal) -Postdural puncture headache (PDPH) -Epidural hematoma -Infection, abscess etc… -Nerve damage (rare) -Backache (more prevalent than with SAB)…30-45% in OB pt)
Epidural hematoma:
-clinically rare; but EMERGENT -s/s back pain and weakness; lower extremity numbness/ paralysis -dx: MRI or CT -Tx: emergent decompression 6-8hr or irrreversible neurological damage
***small amount of local anesthetic is injected directly into the CSF. It produces an intense, rapid, and predictable neural blockade
Spinal
*** requires a tenfold increase in dose (ml) to fill the epidural space and penetrate the nerve roots… slower onset
Epidural
Epidural technique Inserting a needle midline, the anesthetist encounters the following structures:
Skin Subcutaneous fat Supraspinous ligament Interspinous ligament Ligamentum flavum Epidural space “some say sister ida loves ether”
epidural– The layers passed through in a paramedian approach are (from superficial to deep)
Skin, SubQ fat, Ligamentum flavum, Epidural space
2 most common epidural needles:
- Tuohy-most pronounced curvature 2. Hustead-intermediate needle with less-pronounced (15 degree) curvature
Standard epidural needle is : -gauge -length -tip
-16 to 18 gauge -3 inches long, -a blunted bevel and gentle curve of 15-30 degrees at tip
which needle has the most pronounced curvature?
touhy
epidural Catheters- diameter is
2 gauges smaller than needle (20 G catheter might be guided with 18 G needle)
epidural catheter markings are in what increments? -most common?
1 cm markings to measure depth of placement 2 most common: Single holed, open ended (uniport) Lateral holed, closed tip (multiport)
epidural technique pre-op and procedural prep — would you do anything differently from spinal prep?
no - the same
epidural patient positioning
sitting or lateral
process of epidural technique / fyi
-Identify landmarks (mark with finger nail) -Continuously explain procedure to patient -Sterile prep and drapes -Local anesthesia (skin wheel)-1% plain lido -Epidural needle/syringe for technique (bevel up or sideways??) -“pop” when hit Lig. Flavum -LOR when enter epidural space
when do you have loss of resistance?
when enter the epidural space
when will you feel the classic “pop” when performing an epidural?
when hit the ligamentum flavum
*** Signs of intravascular injection…
Assess for : -tachycardia (increase in HR of 10-20 beats per minute), -tinnitus, -metallic taste in mouth, -perioral numbness
**amount of epidural catheter recommended in epidural space?
manufacturer: 1-3cm most providers: 5cm *optimal insertion should be 3-5cm in epidural space
Test Dose is
1.5% with epi
with an epidural; before ever injecting anything what must you do?!
ASPIRATE
epidural injection should be fast or slow?
SLOW!! 3-5 ml at a time; q 3 mins. -avoid rapid increase in CSF/ICP
during epidural injection, what may pt feel?
cramping or cold feeling in back during injection -cramping should go away after injection and should NOT be severe
**Dermatomal blockade is determined mostly by 2 factors:
- Dose of LA (volume multiplied by concentration) 2. Site of injection (site of injection depends on type of surgery etc… L&D, abdominal surgery, thoracic surgery or chronic pain treatment (neck) etc..
**General guide is how many ml per segment?
2 mL per segment blocked -15-20 mL required to ensure adequate anesthesia by blocking 12-16 segments….6-8 above and 6-8 below catheter tip
**Spread of blockade occurs faster in
cephalad direction
Factors affecting spread of epidural:
-Height (really tall or really short) -Weight (morbidly obese) -Age -Patient position during injection (favor dependent portion of body– Some leave pt on operative side while block sets up) -Pregnancy -Speed or mode of injection
in epidurals, vasoconstrictors are used to
prolong block
lower concentrations of LA are used for:
analgesia (l&D, post op pain control)
higher concentrations of LA are used for
analgesia / anesthesia -dense block for surgical procedures
With epidurals, Anesthetic is maintained through :
continuous infusion >lower concentration solutions–0.0625%-0.125% bupivacaine or -0.1% ropivacaine >intermittent boluses higher concentration LA -2% lido, -0.5% ropivacaine
When opioid is administered epidurally, it needs to cross the epidural space through the dura to reach the opioid receptors located in the
substantia gelatinosa in spinal cord
Fentanyl and sufentanil (highly lipid soluble) result in
serologic level of opioid similar to that produced with IV
epidural opioid dosing - low dose vs higher dose
-Low dose infusion or -higher dose intermittent
what epidural morphine is not given in combination with LA?
DepoDur (extended release epidural morphine; given individually only!!)
Time to max spread:
10-25 mins
Assess dermatome:
1-Temperature 2 - Sensation (scratch test) 3. Motor (last lost)
Intradural catheter placement (through dura without penetrating arachnoid membrane)..results in
“patchy block or total spinal like block…. TEST DOSE.. And INJECT SLOWLY.. At all times…
If suspected intradural catheter placement, what do you do?
immediately remove catheter, replace at cephalad level (if fully recovered from symptoms)
Inadequate block, one-sided block, or “hot spots” (single dermatome segment that fails to achieve adequate block) is Treated variety of ways:
-Reposition pt (inadequate block side down) -Administer more LA (increase spread) -Pull catheter back
pediatric caudal indications:
Children having procedures “below the diaphragm: Urogenital, rectal, inguinal, orthopedic and/or lower extremity surgeries
Adult caudal indications:
-anorectoal procedures -L&D failed attempts at epidural placement
if performing caudal in adult, what is are some differences to be aware of (vs. epidural):
-needles w/lateral faced opening is not needed -blunt tip is satisfactory -drugs identical to lumbar epidural block -larger vol is needed to extend block for CS or L&D - 25-35ml
caudal contraindicated in:
pilonidal cysts -b/c INFECTION!
Caudal Adult dosages:
Adult Dosage: -Lidocaine (1.5-2.0%) with or w/o epi. 15-20 ml for a block of lower limb and perineum -Fentanyl 50-100 mcg may be added Maximum Dose : -Bupivacaine- 3 mg/kg -Lidocaine- 5 mg/kg -Lidocaine with Epi- 7 mg/kg
***caudal placement: -position -landmarks
-Sitting or lateral -Identify posterior superior iliac spines (to facilitate identification of sacral cornua) -The sacral hiatus and the posterior superior iliac spines form an equilateral triangle pointing inferiorly. -The sacral hiatus can be located by first palpating the coccyx, then sliding the palpating finger cephalad until a depression in the skin is felt. -Always above intergluteal folds. -skin prep, penetrate Sacral hiatus, change direction, ASPIRATE, check, inject LA
Caudal Pediatric Dose:
Pediatric Dose: 0.5-1.0 mL/kg of 0.125-0.25% bupivacaine (or ropivacaine) with or w/o epi Fentanyl 50-70 mcg may be added
would you recommend a caudal for OP procedures?
not recommended -delayed respiratory depression -analgesic effects of block extend for hours into the post-op period
do you aspirate with a caudal technique?
yes!
Caudal Test dose
-Once the needle is within the caudal canal, 5 mL of NS is rapidly injected while other hand is palpating over the dorsum of sacrum (no mass or pressure wave should be detected over the midline of the sacrum).. -If needle is incorrectly position, fluid mass or pressure wave will be palpated -Administer test dose (exclude intravascular or dural puncture… watch for tachycardia, increasing size of T waves on ECG, total spinal etc…) -Rely on incremental dosing with frequent aspiration (experienced clinician)
**Complications of Caudal:
-Total spinal -Intravenous injection Systemic toxicity Seizures Cardiac arrest -Intraosseous injection Systemic toxicity Seizures Cardiac arrest
note cutting bevels etc
spinal
epidural
lateral landmarks
caudal
cross section of vertebra
dermatomes
c/s - t4
mneumonic
