Epidural Anasthesia Flashcards
Important concepts to remember when administering the LA
Inject slowly,
in 3-5ml increments q 3 min to get desired effect
What is “top off dose?”
When 2 segment regression of the sensory block has occurred, give 1/3 to 1/2 of the initial loading dose of local anesthetic to maintain block
- Always administer a Test dose of…
3ml of1.5% lidocaine w/ 1:200000 epi: 5mcq/ml
Significance:
+ numbness=SAB
+ increase of HR= intravascular
Test dose in subarachnoid
S/S
Spinal anesthesia w/in 3 min
Rapid decrease in HR & B/P
May also see s/s of sensory & motor blockage.
Test dose in a blood vessel
Intravascular
20% in HR & SBP within 30 sec
Change in SBP of >20 mmHg in pt on beta blockers is more indicative of an intravascular injection
What 3 meds always need to be available?
Ephedrine
Phenylephrine
Atropine
What Ned “spares” motor nerves especially in lower concentration?
Bupivacaine
- Identify why thoracic epidural is more difficult to insert & the risks associated w/a thoracic epidural anesthesia
- spinous processes are more angled
- spinal canal is closer to the skin (shallow)
- accidental dura puncture- risk of spinal cord injury
- S/S of local toxicity
Numbness lips & tongue, metallic taste, tinnitus, visual disturbances, muscle twitching, vertigo, seizures, CNS depression/coma, respiratory arrest, CV compromise.
- Why we use additives w/LA for epidural anasthesia
CLONIDINE: prolongs sensory but not motor block, effects occur w/long acting locals
- causes sedation, decrease in B/P & HR
EPINEPHRINE: prolong sensory & motor block of short & intermediate acting LA
- greater decrease in MAP due to beta 2 vasodilation
NARCOTICS: prolong sensory but not motor
BICARBONATE: speeds ones to epidural block
- Identify the difference in motor, sympathetic, & sensory blockade between SABs & epidurals.
SAB/Epidural: Sympathetic, 2 below Sensory desired, 2 below Motor
Epidural
Sympathetic: decreased SVR due to arterial & venous dilation. Less hypotension than a SAB. Bradycardia only if T5 or higher (T1-4)
Motor: variable, depends on amount & concentration of LA
- Lab values for epidural placement
INR must be 100,000 heparin SQ 2hrs after the last dose Lovenox 12 hrs Plavix 7 days Ticlid 14 days
- Epidural blood patch.
How is it done?
What is administered?
Where? How much?
10-20 ml (15 ml) of autologous blood aseptically injected into the next lower interspace, sterile procedure.
Avoiding lifting, straining and air travel for 24-48 hrs.
Can be repeated
90% effective
- Describe the characteristics of the epidural space.
- extends from skull foramen magnum to sacral hiatus
- usually has negative pressure
- widest @ L2 (5-6mm); narrowest @ C5 (1-1.5mm)
- contains: spinal n roots, adipose & connective tissue, lymphatic vessels & blood vessels (sm arteries & veins that form plexus - making placement of catheter more difficult )
8a. Describe the procedure in Administering an epidural anesthetic in midline approach
MIDLINE approach - lumbar or low thoracic epid in the sitting position
- attach monitors, identify levels, spine is prepped & draped sterile, infiltrate skin wheel & deep, insert epidural needle w/stylet through same skin puncture, advance needle through supra and into inters, aprox 3 cm depth, loss of resistance needle w/2-3 cc of air or saline, push needle slowly till loss of resistance, thread catheter 3-5cm into epidural space
8b. Describe the paramedian approach
PARAMEDIAN: for entry level T3-T7, the midline level is impossible to enter due to angulation of the spinous processes.
- skin wheel 1.5-2 cm. lateral to midline
- needle advance perpendicular to skin until the lamina is encountered
- needle redirected & advanced @ 10-15 degree angle toward midline
- needle is “walked off” the bone into the ligamentum flavum
- needle penetrates para spinous muscle w/little resistance b4 entering ligamentum flavum
- Recognize the significant of test dose
3ml of 1.5% lidocaine w/ 1:200,000 epinephrine (5mcq/ml)
-If SAB = w/in3 min, decrease of HR & B/P, sensory & motor blockade
-If intravascular = 20% increase in HR & SBP w/in 30sec. A change in SBP >20 mm Hg in pts w/beta blocing agents is more indicative of an intravascular injection
LA toxicity may be also seen.
- Identify anatomical structures associated w/ epidural insertion
Skin–sub q tissue–supraspinous ligament–interspinous ligament–ligamentum flavum–epidural space–spinal cord
Midline: insert needle between spinal processes
Paramedian: insert 1cm lateral to the spinous process & perpendicular to skin–contact lamina & walk off the edge to ligamentum flavum
Anasthesia of first stage of labor
T10-L1 dermatomes anesthetic
Widest epidural space
L2 (5-6mm)
Narrowest epidural space
C5 (1-1.5mm)
Which LA can have tachyphylaxis?
Lidocaine 1.5-2%
Second stage of labor
S2-4 segments due to vaginal distention &perineal pressure
Initial dosing for
Thoracic
Lumbar
Thoracic poke 6-8 ml: short reduce by 1-2; tall pts increase by 1-6 ml Lumbar poke L3: 8-12 ml T10: 10-14 ml T4: 20-25 ml (ex. C-section)
- Potential complications and Rx
Pruritis due to narcotics: Nalmene or Benadryl
Nausea & Vomiting: Nalmene or antiemetic
Urinary retention: Foley cath, straight cath or d/c urinary cath
No pain relief: catheter not in correct spot….
- How hemodynamics may be effected with epidural
- Hypotension: IVF, Ephedrine, Phenylephrine
- Decrease SVR
- Bradycardia: if level T5 or higher watch with c-section
- What is caudal anesthetic?
Common in peds: epidural cath or single injection for post op pain
Adults: used for procedures requiring blockage of the sacral & lumbar nerves & for chronic pain Rx.
Bupivicane .25 2mg/kg, onset 12min, duration 43hrs
Ropivicane .2 2mg/kg. onset 9min, duration 17hrs
- How do you know if epidural is working?
No pain in the surgical area
Anatomy & dermatomes
Perineum s2-s4 Lateral foot s1 Knee/thigh L3-L4 Superior iliac crest L4 Umbilicus T10 Xiphoid T6-8 Nipples T4-5 C7 C4 clavicle
Surgical procedures and recommended peak block
T1: upper abd, chole, expl
T4-6: lower abd, TAH, vs, hernia, appy
T6-8: TURP, vaginal delivery, total hip, fem-pop
T8-10: LE w/tourniquet, knee replacement, BKA
S4-L1-2: percirecatal, perineal (hemorrhoidectomy, transvag sling
