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AS - N931 Advanced Principles of Anesthesia > Epidural & Spinal > Flashcards

Epidural & Spinal Flashcards

1
Q

Epidural Anesthetic

A

Reversible neuronal transmission chemical blockade produced via LA injection into the EPIDURAL space (above the dura)
Local anesthetic leaks into intravertebral foramen & paravertebral spaces
Medication spread = diffusion dependent
Longer onset 15-20min
Temporary interruption autonomic, sensory, & motor nerve fiber transmission r/t drug concentration & volume

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2
Q

Epidural Advantages

A

↓surgical stress (therefore opioid consumption)
Blunts SNS response
↓blood loss - controversial d/t hypotension
↓DVT risk r/t coagulation cascade
Titratable, able to re-dose w/ catheter, convert from pain management to 1° anesthetic (labor epidural)
Versatility to control the sensory & motor blockade extent
Used w/ or w/o adjunct medications

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3
Q

Epidural & Spinal Disadvantages

A

Post-dural puncture headache
Sympathetic blockade → hypotension & bradycardia
Block lasts much longer than the procedure +/-
Urinary retention (more common spinal side effect)
Regional takes too much time - more difficult than a spinal

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4
Q

Epidural/Spinal ABSOLUTE Contraindications

A 
Patient refusal
↑ICP (herniation risk)
Severe aortic or mitral valve stenosis ↓SNS → relative
Coagulopathy or bleeding diathesis
Severe hypovolemia
Infection at injection site
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5
Q

Epidural/Spinal Relative Contraindications

A 
Uncooperative patient
Local anesthetic allergy
Anticoagulant or thrombolytic therapy
Pre-existing neurologic deficit
Chronic headache or backache (document baseline)
Severe spinal deformity
Valvular stenosis
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6
Q

Epidural/Spinal Pre-Procedure Monitoring

A 
Patent large bore PIV
Suction
Airway supplies
Difficult airway equipment
EKG, BP, SpO2, ETCO2
Oxygen
Medications - induction, paralytic, atropine, vasoactive
Support person
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7
Q

C7

A

Most prominent cervical process

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8
Q

T7

A

Scapula inferior tip

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9
Q

L4

A

Tuffier’s line

Superior iliac crest aspect

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10
Q

Epidural/Spinal Positioning

A

Sitting, lateral decubitus (hip fracture), prone
Needle approaches - midline or paramedian
Placement - thoracic, lumbar, or caudal
Assistant/support person
Patient hold pillow or blanket or lean over table
- Drop head down & roll his/her back
- Push out against hand on back to ensure correct position
Proper positioning = key to successful procedure
Spine flexion → increases interspinous spaces
Flex at neck & back not only hips to optimize the interspinous space

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11
Q

Epidural Procedure

A
  1. Proper positioning
  2. Palpate landmarks
  3. STERILE procedure (hat, mask, & sterile gloves)
  4. Open tray
  5. Cleanse injection site & allow to dry completely
  6. Set-up tray & draw up meds
  7. Apply sterile drape
  8. Re-position patient & identify injection site
  9. Inject local anesthetic 25-27G
  10. Place epidural Tuohy needle
  11. Attach normal saline syringe
  12. Advance 1mm until lose resistance
  13. Removed syringe & thread the catheter 3-5cm past the needle hub
  14. Remove needle PRIOR to pulling the catheter back
  15. Test dose
  16. Secure the catheter
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12
Q

Tuohy Needle

A 
Pronounced curve
Orient bevel up
Blunt tip to help prevent damage to structures
Marked at 1cm increments
Standard = 9cm
Longer & more rigid needles
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13
Q

Crawford Needle

A 
Epidural needle
Not curved
Easier to insert
↑dural puncture rate
Requires more skilled clinician
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14
Q

Standard Depth at Lumbar Level

A

5cm (2.5-8cm) to the ligamentum flavum

Depth & needle angle changes based on vertebral level

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15
Q

Bromage Grip

A

One-hand grip firm support to stabilize the needle
Attach & secure the syringe (filled w/ air or saline)
Pass the catheter through the needle

Alternative - stabilize needle on both sides (two-handed)
More stability as advancing needle

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16
Q

Hanging Drop Method

A

Less common
Epidural needle hub filled w/ saline until small drop visible
Negative pressure created as needle passes into epidural space “sucks” the drop in
More pronounced at thoracic levels

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17
Q

Epidural Space Dilation

A 
Loss resistance noted when needle passes through the epidural space
Syringe contents (air or saline) injected into the epidural space
When syringe removed common to see small amount clear fluid
Puncturing the dura results in profuse CSF return
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18
Q

Epidural Catheters

A 
Typically 2 gauges smaller than the needle
Open-ended or multiport
Dashed lines = 1cm
Two-dashed lines = 10cm
Thick line = 12cm
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19
Q

Parethesia

A

Inform/prepare the patient prior to procedure about the steps & what to expect
When to notify provider (i.e. parethesia or pins & needles sensation)
Catheter has entered the nerve root
Withdraw the catheter

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20
Q

Catheter Advancement

A

Noted needle location at the skin
Advance catheter 3-5cm past needle hub
Ensure adequate catheter available to hold securely when removing needle
Unable to pull back catheter while needle in & unable to re-advance once needle removed

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21
Q

Shallow Placement

A

Potential to results in dislodgement from the epidural space

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22
Q

Deep Placement

A

Dura puncture risk
Passage into the epidural vein
Migration through the intervertebral foramen

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23
Q

Test Dose

A

1.5% Lidocaine w/ Epi 1:200,000 or 5mcg/mL
Inject 3mL = 45mg Lidocaine & 15mcg Epi
Subarachnoid space → spinal anesthetic
Intravascular → >20% increase HR & BP
Note vital signs before test dose & ask patient about last contraction

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24
Q

Paramedian Approach

A

Patient unable to flex spine - previous spine surgery, rheumatoid arthritis, or hip/upper leg trauma
Skin wheal 1cm lateral & 1cm caudal to spinous process
Advance needle toward midline
- Needle passes through paraspinous muscles to ligamentum
- Does NOT pas through supraspinous or interspinous ligaments

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25
Q

Trouble Shooting

Contacting Bone

A

Withdraw the needle & stylet to subcutaneous fat
Reposition the introducer & reinsert the needle
- Needle touching the spinous process superior crest below the interspace → redirect cephalad
- Needle touching the spinous process inferior surface process above the interspace → redirect caudal
- Repeatedly encounter bone → remove the needle & reassess landmarks

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26
Q

Trouble Shooting

Paresthesia

A

Patient experiences paresthesia during catheter insertion
Sharp, shooting pain indicates needle w/in nerve root
STOP
- Resolves → continue w/ procedure
- Persistent → withdrawal & reposition

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27
Q

Trouble Shooting

Blood in Catheter

A

Frank blood vs. blood-tinged
Continuous blood - withdraw the catheter & replace
Blood-tinged that clears up continue

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28
Q

Caudal Anesthesia

A 
Distal approach to the epidural space
Indications:
- Hemorrhoidectomy
- Chronic pain patients
- Pediatric analgesia (inguinal herniorrhaphy, circumcision, & perineal procedures)
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29
Q

Caudal Dosing

A

0.5-1mL/kg
2.5mg/kg
Adult test dose 12-15mL sacral anesthesia
Lower extremity procedures 20-30mL

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30
Q

Combined Spinal-Epidural

A

CSE

Offers advantages of both spinal & epidural anesthesia w/ reducing the disadvantages

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31
Q

One-Level CSE

A

Place epidural needle
Spinal needle passed through
Small intrathecal dose injected
Epidural catheter place

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32
Q

Two-Level CSE

A

Spinal placed first

Epidural catheter placed 1-2 levels above

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33
Q

Parasagittal U/S

A

Low frequency curvilinear transducer
Paramedian (off midline)
Longitudinal view
Located sacrum 1st = fused (hyperechoic line)

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34
Q

Axial U/S

A

Low frequency curvilinear transducer
Transverse (horizontal)
Midline view
Identify spinous processes “unicorn or traffic cone”
Then move up to down to locate BATMAN sign
Measure distance (depth) to ligamentum flavum

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35
Q

Esters

A

Procaine
Chloroprocaine
Tetracaine

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36
Q

Amides

A

Lidocaine
Mepivacaine
Ropivacaine
Bupivacaine

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37
Q

How to administer neuraxial injection?

A

Only after negative aspiration

NEVER MORE THAN 3-5mL

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38
Q

Local Anesthetic Dosing

Based on Spinal Levels

A

Caudal 2mL/segment
Lumbar 1mL/segment
Thoracic 0.7mL/segment

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39
Q

Epinephrine

A

α1 agonist
1:200,000 (indicates gram per mL = 5mcg/mL)
Prolongs DOA w/ short-acting LAs
Greatest effect w/ Tetracaine

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40
Q

Clonidine

A

NOT vasoconstrictor
Selective α2 agonist
Used when Epi contraindicated
Synergistic effects when mixed w/ Lidocaine or Bupivacaine (labor analgesia)
Central action appears to help w/ tourniquet pain (ortho surgeries)

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41
Q

Epidural Fentanyl

A

High lipid solubility
PK/PD similar to systemic administration
Provides profound analgesia

Dose: 50-100mcg
Onset: 3-5min
DOA: 1-2hrs

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42
Q

Epidural Morphine

A

Highly polarized, not very lipid soluble
PK/PD similar to systemic admin
Provides profound analgesia

Dose: 2-4mg
Onset: 10-15min
DOA: 8-10hrs

Adverse effects - itching & urinary retention

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43
Q

Patient Controlled Epidural

A

Low concentration infusion + additive

Able to inject additional LA

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44
Q

GOAL

A

Block A delta & C fibers

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45
Q

Nerve Block Onset

A

B → A delta & C → A gamma → A beta → A alpha

46
Q

B Fiber Block

A

Pre-ganglionic autonomic vasomotor
Diameter < 3μm
Light myelination
Onset = early

Rapid 1st sympathetic
Hypotension r/t level
T4 = cardiac accelerator fibers
1st sign ↓BP followed by N/V 
Typically N/V 1st patient noted sign → cycle BP cuff
47
Q

A Delta & C Fibers

A

Pain & temperature
Unable to discriminate light touch or temperature
Temperature discrimination mirrors sensory loss

48
Q

A Delta

A
  • Pain, cold temperature, touch
  • 1-5μm
  • Heavy myelination
  • Intermediate block onset
49
Q

C Fibers

A

Sympathetic:

  • Post-ganglionic vasomotor
  • 03-1.3μm

Dorsal root:

  • Pain, warm & cold temperature, touch
  • 0.4-1.2μm

Both:

  • No myelination
  • Early block onset
50
Q

A Fibers

Alpha, Beta, & Gamma

A

Last fibers to be blocked

  • Touch & proprioception
  • Surgical muscle relaxation
  • Able to feel pressure
51
Q

A Alpha

A

Proprioception, motor
6-22μm
Heavy myelination
Onset = last

52
Q

A Beta

A

Touch, pressure
6-22μm
Heavy myelination
Intermediate onset

53
Q

A Gamma

A

Muscle tone
3-6μm
Heavy myelination
Intermediate onset

54
Q

Evaluation

Assess the block every ___ minutes

A

2-3 minutes

Vital signs & blood pressure

55
Q

How to manipulate the LA spread?

A

Adjust the OR table level
Trendelenburg or reverse
Local anesthetic baricity impact compared to CSF specific gravity

56
Q

Physiologic Alterations

A

Dependent on block level
Assess dermatomes & sensory changes
Manipulation to LA spread via positioning
Elevate HOB to prevent cephalad spread & post-dural puncture headache
Autonomic blockade usually 2 dermatome levels higher than sensory block level
Motor block upper limit usually 2 levels below the sensory block

57
Q

Epidural/Spinal Complications

A 
Hypotension
Intercostal muscle paralysis
Apnea/phrenic nerve paralysis
Paresthesias
Subarachnoid or epidural hematoma
Infections:
- Meningitis/epidural abscess
- Chemical meningitis
- Prevention = proper sterile technique
Cauda equina syndrome
Transient neurological symptoms
New nervous system lesion
Exacerbation pre-existing neurological disease
N/V
Urinary retention
Post-dural puncture headache
58
Q

Post-Dural Puncture Headache

A

Results d/t dura compromise
Obvious or following uncomplicated procedure
Risk factors - needle size/type & patient population (younger, female, & pregnancy)

59
Q

PDPH S/S

A

Bilateral frontal or retroorbital or occipital headache
Extends into neck
Photophobia
Nausea
Positional - headache relieved when supine
S/S exacerbated when upright

60
Q

PDPH Treatment

A

1st 12-24hrs conservative
- Recumbent position (supine)
- Analgesics
- Fluid admin
- Caffeine
- Stool softeners & soft diet (to prevent straining)
Epidural blood patch
- Inject 15-20mL autologous blood (obtain simultaneously w/ sterile procedure)
- Admin 1-2 levels below initial puncture site
- 90% respond to initial therapy

61
Q

Cauda Equina Syndrome

A

PERMANENT neurological deficits
Results in bowel and/or bladder dysfunction, perineal sensory loss, & variable extremity paresis
Onset usually immediate after causative injury
1991 microcatheters r/t large amounts concentrated LA pooling at the lumbosacral roots → excessive exposure & toxic effects
Treatment = supportive

62
Q

TNS

A

Transient neurologic symptoms
1993 after single-dose spinal anesthesia
NOT permanent deficit (transient)
Temporary symptoms appear 1-24hrs after spinal anesthesia resolution
Disappears w/in 10 days
Pain syndrome (no bowel or bladder dysfunction)
Back pain, weakness/numbness radiating one or both buttocks or legs, & thighs
Lidocaine more neurotoxic than Bupivacaine or Tetracaine
Contributing factors - lithotomy position or hip/knee bent (thought to be r/t LAs pooling & lumbosacral nerve roots stretching)

63
Q

Spinal Anesthetic

A

REVERSIBLE neuronal transmission blockade produced via LA injection into the CSF
Subarachnoid or intrathecal block
Temporary interruption autonomic, sensory, & motor nerve fiber transmission (ventral & dorsal nerve roots)

64
Q

August Bier

A

Performed the first spinal anesthetic 1898

Injected 15mg cocaine intrathecally

65
Q

Spinal Advantages

A

Ideal technique for lower abdomen & caudal procedures
Simple & versatile
- Able to control block distribution
- Use w/ or w/o adjunct anesthesia
↓surgical stress
↓blood loss - controversial d/t hypotension
↓DVT risk r/t coagulation cascade
Postop analgesia
Awake patient - no LOC
Full stomach (non-compliant NPO or delayed gastric emptying)
↓PONV, sedation, cognitive impairment, & surgical pain

66
Q

Spinal Technique Selection

Indications & Patient Considerations

A

Procedures involving lower extremities or lower abdomen
Patients with pulmonary disease (avoid negative pulmonary effects associated w/ general anesthesia)
Preop assessment
Address any patient concerns
Plan B = general anesthesia

67
Q

Spinal Indications

A 
Full stomach
Difficult airway
Minimal metabolic impact - liver or kidney disease or diabetes
↓systemic blood pressure
- Risk venous thrombosis & blood loss
68
Q

Aortic Valve Stenosis

MILD

A

Jet velocity <3m/sec
Mean gradient <25mmHg
Valve area >1.5cm^2

69
Q

Aortic Valve Stenosis

MODERATE

A

Jet velocity 3-4m/sec
Mean gradient 25-40mmHg
Valve area 1-1.5cm^2

70
Q

Aortic Valve Stenosis

SEVERE

A

Jet velocity >4m/sec
Mean gradient >40mmHg
Valve area <1cm^2

71
Q

Aortic Valve Stenosis

CRITICAL

A

Jet velocity >5m/sec
Mean gradient >80mmHg
Valve area <0.7cm^2

72
Q

Other Epidural/Spinal Considerations

A

Previous back surgery
Inability to communicate w/ patient
Complicated surgical procedures - long duration, major blood loss, or respiratory compromise
Local anesthetic allergy (amide vs. ester)
Untreated HTN
Major surgery above the umbilicus d/t blockade level (motor vs. sensory)

73
Q

Dural Puncture (Spinal) Location

A

Anywhere from L2 → S1
Spinal cord ends at L1 in adults
Most common location L3-L4 interspace

74
Q

Procaine

A 
Ester
pKa 8.9
Ionized 97%
Protein binding 6%
Onset - slow
DOA 60-90min
75
Q

Chloroprocaine

A

Ester

Onset - fast
DOA 30-60min

76
Q

Tetracaine

A 
Ester
pKa 8.5
Ionized 93%
Protein binding 94%
Onset - slow
DOA 180-600min
77
Q

Lidocaine

A 
Amide
pKa 7.9
Ionized 76%
Protein binding 64%
Onset - fast
DOA 90-120min
78
Q

Mepivacaine

A

Amide

Onset - fast
DOA 120-240min

79
Q

Ropivacaine

A

Amide

Onset - slow
DOA 180-600min

80
Q

Bupivacaine

A 
Amide
pKa 8.1
Ionized 83%
Protein binding 95%
Onset - slow
DOA 180-600min
81
Q

Baricity

A

Resting position of two fluids w/ different specific gravities when mixed in single container
Pertaining to spinal anesthetics & baricity hyper/iso/hypo vs. CSF

82
Q

CSF Specific Gravity

A

1.003-1.009

Denser than water

83
Q

Isobaric

A

LA = baricity as CSF

Normal saline or CSF

84
Q

Hyperbaric

A 
LA heavier (more dense) than CSF
Dextrose
85
Q

Hypobaric

A 
LA lighter (less dense) than CSF
Sterile water
86
Q

Anesthetic Level Factors

A 
BARICITY *spinal only*
Patient position
Drug dosage
Injection site
Patient height
- Short ↓LA dose/volume
- Tall ↑dose/volume
Pregnancy - epidural vein engorgement
CSF volume
Spine curvature
Drug volume
Intra-abdominal pressure
Needle direction
87
Q

Most Dependent Spinal Area

A

T4-T8

Hyperbaric solutions mitigate here most when patient supine

88
Q

Spinal Procedure

A
  1. Verify patient, patent IV, monitors attached & functioning, resuscitation equipment available
  2. Inform patient about procedure & steps involved
  3. Properly position patient at comfortable level
  4. Palpate & identify landmarks
  5. STERILE procedure (hat, mask, & sterile gloves)
  6. Open tray
  7. Cleanse injection site & allow to dry completely
  8. Set-up tray & draw up meds
  9. Apply sterile drape
  10. Re-position patient & identify injection site
  11. Inject local anesthetic 25-27G
  12. Place introducer needle
  13. Pass spinal needle through the introducer
  14. Advance through posterior ligaments
  15. Utilize non-dominant hand to stabilize needle
  16. Remove stylet & observe clear CSF flow
  17. Connect LA syringe, aspirate to confirm CSF (distinct swirl noted), inject LA
  18. Removed syringe, needle, & introducer together in one smooth motion
  19. POSITION
89
Q

Spinal Bilateral Block

A

Return patient to supine position immediately

Slightly elevate HOB to prevent PDPH

90
Q

Spinal Unilateral Block

A

Leave patient in lateral position at least 3 MIN prior to returning to supine position
Slightly elevate HOB to prevent PDPH

91
Q

Spinal Needles

A

Cutting vs. pencil point
Quincke 25G (cutting)
- Orient bevel to the side ↓tissue trauma
- Dural trauma more common
Sprotte 25G or Whitacre 25G (pencil point or blunt tip)
- Separates the tissues

92
Q

SPINAL Trouble Shooting

Absence CSF

A

Reinsert stylet
Slowly advance needle 1-2mm
Attempt to aspirate CSF
Repeat steps until obtain CSF
Advance needle additional mm after puncture to ensure complete dura puncture (especially w/ pencil point needles)
Traverse the dura - remove stylet & attach syringe, gently aspirate as withdraw needle, as needle tip withdrawn into subarachnoid space may obtain CSF
↑risk PDPH

93
Q

SPINAL Trouble Shooting

Blood-Tinged CSF

A 
FRANK blood
- Does not clear
- Needle tip likely w/in an epidural vein
- Withdraw & reposition
Blood-tinged CSF
- Allow CSF to flow for several seconds
- Inject medication when CSF clear
94
Q

SPINAL Trouble Shooting

Paresthesia

A

STOP
Leave the needle & stylet in place
Paresthesia resolves then continue w/ the injection
Does not resolve then remove & reposition the needle

95
Q

Sensory Blockade at T10

AUTONOMIC

A

Autonomic blockade 2 dermatome levels HIGHER
→ T8
Cardio-accelerator fibers at T4
Autonomic blockade >T4 → systemic hypotension

96
Q

Sensory Blockade at T4

MOTOR

A

Motor blockade usually 2 levels BELOW the sensory block → T6

97
Q

Saddle Block

A

S2-S5
Surgery limited to perineum, perianal region, or genitalia
Little autonomic effect

98
Q

Low Spinal

A

T10
Low abdominal procedures & lower extremity vascular & orthopedic
Block lower lumbar & sacral roots

99
Q

High Spinal

A

C8
Block higher than T2
Undesirable effect → unable to ventilate

100
Q

Most Common Spinal

A

T4

Abdominal & lower extremity procedures

101
Q

Obese Patients

A

Spinous processes more difficult to palpate
- Adipose tissue distorts anatomic landmarks
Sitting position provides more flexion
ULTRASOUND

102
Q

Paramedian Approach

A

When patient unable to flex spine - previous spinal surgery, rheumatoid arthritis, or trauma to hip or upper leg
Place skin wheal 1cm lateral & 1cm caudal to spinous process
Advance needle toward midline
- Needle passes through paraspinous muscles to ligamentum
- Does NOT pass through supraspinous or interspinous ligaments
- Ligamentum flavum = 1st encountered ligament

103
Q

Lumbosacral Approach

A

Modified paramedian approach
L5 → S1 interspace
Identify posterior superior iliac spine
Skin wheal 1cm medial & 1 cm caudal to the spine
Needle insertion 45-55° medial & cephalad to the dorsal sacrum surface toward the lumbosacral foramen midline

104
Q

Continuous Spinal

A

Prolonged surgical anesthesia & postop pain
Dura punctured w/ 17G epidural needle
Epidural catheter passed through dura into subarachnoid space
Small, incremental doses LA admin until desired level achieved
- Slows hypotension onset
- Total dose to achieve the desired level = same
Consider using wet tap occurs when placing an epidural

105
Q

LA Metabolism

A

Little to no metabolism in CSF
Absorbed into plasma & metabolized based on physiochemical properties (esters plasma esterases via hydrolysis; amides hepatic CYP require transport to liver)
+ vasoconstrictors slows the absorption & prolongs the block

106
Q

Phenylephrine

A

Pure α adrenergic agonist
Slightly more effective than Epi
Greatest effect w/ Tetracaine

107
Q

Intrathecal Opioids

A

PRESERVATIVE FREE
Synergism b/w opioids & local anesthetics
Provide better analgesia together rather than alone
Fentanyl & Morphine

108
Q

Spinal Fentanyl

A

High lipid solubility
- Binds directly to spinal cord lipid elements
- Less drug available to diffuse systemically
Provides profound analgesia

Dose: 12.5-25mcg mixed w/ LA
Onset: 5-10min
DOA: 2-4hrs

109
Q

Spinal Morphine

A

Highly polarized, not very lipid soluble
- Drifts feely in CSF
- Approximately 6-8hrs rises to respiratory center
Provides profound analgesia

Dose: 0.1-0.25mg
Onset: 60-90min
DOA: 24hrs

Adverse effects - itching, urinary retention, & delayed respiratory depression

110
Q

Documentation

A

Informed consent
Oxygen & monitors applied
Baseline vital signs
Patient properly positioned
Prepping & draping performed in sterile fashion
Desired interspace identified
Skin wheal subcutaneous LA (amount mL)
Introducer placed w/ spinal needle passed through
Positive clear CSF noted (negative for blood or paresthesias)
Dose LA as well as any other adjuncts
Patient placed in desirable surgical position
Final dermatome level achieved

AS - N931 Advanced Principles of Anesthesia (17 decks)

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