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Principles of Anesthesia I 2024 > Exam 1 Spinal & Epidural Neuraxial Anesthesia [06/04/24] > Flashcards

Exam 1 Spinal & Epidural Neuraxial Anesthesia [06/04/24] Flashcards

1
Q

What are the common causes of unilateral epidural blocks?

A
  • The catheter may have been inserted too far, exiting the epidural space through intervertebral foramen.
  • The catheter tip might be too close to a nerve

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2
Q

What are the solutions for unilateral epidural blocks?

A
  • Adjust the Catheter: Pull the catheter slightly, about 1-2 cm, but ensure at least 3 cm remains in the epidural space.
  • Reposition the Patient: Lateral Decubitus Position: Lay the patient on their side with the side not feeling numb facing downwards.
  • Administer More Anesthetic: Dilute Anesthetic: Inject a diluted local anesthetic to try to even out the block.
  • Catheter Replacement: If adjustments and additional anesthetic don’t resolve the issue, the catheter may need to be replaced.

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3
Q
  • What is the most common cause of Local Anesthetic Systemic Toxicity [LAST]
  • most frequent symptom?
  • What is it common in?
A
  • most common cause of Local Anesthetic Systemic Toxicity [LAST]: inadvertent injection
  • most frequent symptom: seizure. Yet, with bupivacaine, cardiac arrest may come first before seizure.
  • LAST is more common in peripheral nerve blocks than in epidural.

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4
Q

CNS effect of Lidocaine toxicity:
* 1-5 mcg/ml
* 5-10 mcg/ml
* 10-15 mcg/ml
* 15-25 mcg/ml

A
  • 1-5: analgesia
  • 5-10: tinnitus, skeletal muscle twitching, numbness of lips/tongue
  • 10-15: seizures, loss of conciousness
  • 15-25: coma

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5
Q

Cardiopulmonary effect of Lidocaine toxicity:

  • 5-10 mcg/ml
  • 15-25 mcg/ml
  • > 25 mcg/ml
A
  • 5-10: hypotension, myocardial depression
  • 15-25: respiratory arrest
  • > 25: cardiovascular collapse

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6
Q

Risk of CNS toxicity with LAST increases with?

A

Hypercarbia:
* Increases cerebral perfusion, increasing drug delivery to the brain
* Decreases protein binding, increasing the free fraction of LA available to enter the brain

Hyperkalemia
* Neurons are more excitable and likely to depolarize

Metabolic Acidosis
* Lowers seizure threshold and increases brain drug retention (ion trapping).

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7
Q

Risk of CNS toxicity with LAST decreases with?

A

Hypocarbia
* Decreases cerebral perfusion, reducing drug delivery to the brain

Hypokalemia’
* Neurons are less excitable and require larger stimuli to depolarize

CNS Depressants (like benzodiazepines and barbiturates)
* Raise the threshold for seizures, providing protection.

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8
Q

What is the impact of LA on heart functions? [CV toxicity]

A
  • Decrease the heart’s automaticity, conduction velocity, action potential duration, and the effective refractory period.
  • Depress myocardium by affecting intracellular calcium regulation.

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9
Q

What are the key factors in determining the extent of cardiotoxicity?

A
  • LA affinity to the voltage-sodium channel in the active and inactive states.
  • Rate of dissociation from the receptor during diastole

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10
Q

What is the primary reason why cardiac morbidity is high with bupivacaine and resuscitation is very difficult?

A
  • Bupivacaine has a high affinity to the voltage-sodium channel and a slower dissociation rate from the receptor during diastole.

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11
Q

Difficulty of cardiac resuscitation [greatest to least]

A
  • bupivacaine > levobupivacaine > ropivacaine > lidocaine

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12
Q

List the treatments of LAST

A
  1. Manage the Airway: Give 100% oxygen
  2. Treat Seizure:
    -Use Benzodiazepines: These drugs help control seizures.
    -Avoid Propofol: It can weaken the heart in large doses and doesn’t replace lipid therapy.
  3. Modified ACLS
  4. Lipid emuslion therapy

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13
Q

How do you modify ACLS for tx of LAST?

A
  • Be cautious with Epinephrine: It can make LAST resuscitation harder and lower the effectiveness of lipid therapy.
  • Use less than 1 mcg/kg.
  • Use Amiodarone for ventricular arrhythmias

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14
Q

How is lipid emulsion therapy given?

A

Over 70 kg:
* Start with a 100 mL bolus for 2-3 minutes
* followed by a 250 mL infusion over 15-20 minutes.
* Repeat or double if unstable.

Under 70 kg:
* Start with a 1.5 mL/kg bolus for 2-3 minutes
* followed by a 0.25 mL/kg/min infusion.
* Repeat or double if unstable.
* Continue the infusion until 15 minutes after stability is regained.

Maximum dose: 12 mL/kg.

If unresponsive to modified ACLS and lipid therapy, prepare for cardiopulmonary bypass

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15
Q

Explain the MOA of lipid emulsion therapy?
* Lipid sink:
* Metabolic effect:
* Inotropic:
* Membrane effect:

A
  • Lipid sink: Sequesters and reduces LA plasma concentration
  • Metabolic effect: Boosts myocardial fatty acid metabolism; increases heart energy use.
  • Inotropic: Increases heart muscle calcium levels by increasing calcium influx and intracellular calcium concentration
  • Membrane effect: Impairs LA binding to voltage-sodium channel

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16
Q

Once last is stable, what do you do?

A
  • Continue lipid emulsion >15 min
  • Max: 12 ml/kg

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17
Q

LAST checklist

A
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18
Q

What meds do you avoid in LAST?

A
  • local anesthetics
  • beta blockers
  • CCB
  • vasopressin

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19
Q

What are Epidural/Spinal Hematoma associated with?

A
  • Preexisting abnormalities in clotting hemostasis
  • Traumatic or difficult needle placement
  • Indwelling catheters and long-term anticoagulation

Overall low incidence [1:200K]

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20
Q
  • Whare are the s/sx of epidural/spinal hematoma?
  • If epidural/spinal hematoma occurs, how do you reverse cord ischemia?
  • Why do we worry about this as CRNAs?
A
  • Symptom of numbness/weakness confusing by the use of local anesthetics; Pain is a major symptom!!
  • Laminectomy is performed in < 8 hours
  • Large jury awards [among other things]

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21
Q

105 and 108-116

  • ____ is inflammation of meninges associated with what 3 things?
  • What does arachnoiditis lead to?
A
  • Arachnoiditis is inflamation of meninges
  1. Nonapproved administration of drug into intrathecal or epidural space (medical error)
  2. Using non-preservative free solutions
  3. Betadine contamination (wipe off)
  • Leads to extensive sclerosis of arachnoid membranes and constriction of vascular supply

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22
Q
  • ASA (since 1990) make up what percent of nerve injury claims?
  • spinal cord injury rates were higher than ____ injuries causing ____ nerve damage.
  • This is caused by blocks done on ____ patients and ____ ____ patients.
A
  • 19%
  • positioning, ulnar
  • anticoagulated and chronic pain

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23
Q
  • There were ____ deaths from cardiac related events after ____ anesthesia.
  • anesthesia contributed to ____ % of those cases d/t undetected ____ ____ and ____ blockade
A
  • 14, spinal
  • 54%
  • undetected respiratory compromise and sympathetic blockade

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24
Q
  • With EVERY neuraxial case we should be prepared to do ____.
  • What problems might lead to us needing to do a general? (6)
A

GENERAL!
* Failed block
* “High spinal”
* LAST
* Anaphylaxis
* Severe CV collapse
* Case exceeds duration of local anesthetic

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25
Q

What are 3 common reasons for failure of neuraxial anesthesia?

A
  • wrong dose
  • wrong location
  • wrong position

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26
Q

What are the common components to a spinal Kit?

A
  • 3.5 inch, styleted needle (avoid microclots)
  • Introducer
  • Local anesthetic
    • Skin (1% lidocaine -5ml glass vial)
    • SAB (2 ml total)
      • Baricity (Hyperbaric, Isobaric, or Hypobaric)
  • Prep (Types: Chlorohexidine/Betadine)
  • Sterile Drapes
  • Needles (22 g or smaller (skin) and 18 gauge and filter needle)
  • Sterile gloves, hats (both patient and you), and a mask for anesthesia provider

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27
Q

Spinal needles consist of two parts: ____ and ____, which is what type of needle?

A

introducer and spinal needle which is a pencil point needle

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28
Q

What are the 2 types of spinal needles?

A

Cutting and non-cutting

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29
Q

Examples of cutting needles for spinals.
What are we at risk for with Cutting needles

A
  • Quincke (25g) and Pitkin
  • PDPH

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30
Q

Examples of non-cutting spinal needles

A
  • sprotte (25g)
  • whitacre (25g)
  • pencan
  • greene
  • gertie marx (26g)

Gertie marx Green Worn Pen Stinks

S113

31
Q

What are 3 major benefits to using a pencil-point tip in SAB?

A
  • Pencil-point needles “drag” fewer contaminants into subnormal tissue.
  • A “click” or “pop” can be sensed with a pencil point needle
  • Carries significantly less risk of PDPH
    • Associated with less than a 1% risk of PDPH and a failure rate of about 5%.

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32
Q

A spinal procedure should start w/ a timeout. What are the componets of a timeout?

A
  • pt ID
  • consent
  • allergies
  • site

CAPS

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33
Q

What monitors might be used for a spinal?
When should they be placed on the pt?

A
  • BP and O2 saturation
  • placed before the procedure begins

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34
Q

Step by step spinal procedure after timeout and monitors

This is how TITO performs a spinal, said we dont have to know.

A
  1. Positioning “mad cat”
  2. ID/mark interspace for SAB
  3. Sterile prep with 3 sponges
  4. Drape
  5. Draw up meds (SAB filter)
  6. Wipe excess betadine off
  7. Localize skin 1% lidocaine. (give all 5mL!!, use as marker)
  8. Place introducer
  9. Insert spinal needle
  10. Once the dura is traversed, you will feel or hear a “pop”
  11. Withdraw stylet and watch for CSF flow
  12. Rotate the needle 360 degrees to get good flow if needed
  13. Aspirate CSF with syringe of SAB LA “swirl” (Hyperbaric)
  14. Inject SAB local anesthetic
  15. Lay flat
  16. BP/HR evaluation
  17. Dermatome Assessment
  18. Reposition to prevent “high spinal” (1st 5 minutes) [arms out to the side]

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35
Q

What are common provider problems encountered with SAB procedure? (8)

A
  • Lack free flow CSF when spinning 360 degrees
  • No swirl (could still be in correct spot if volume in syringe increases or hyperbaric wasnt used)
  • Resistance with injection
  • Paresthesia (STOP! reposition)
  • Checking swirl halfway/end? (provider dependent)
  • Blood instead of CSF (slight blood continue, a lot of blood: stop!) [if in vein, reposition midline]
  • No block (lot numbers/expiration date should be checked at the beginning)
  • Partial block (single shot!)

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36
Q

List the contents found in an epidural kit!

A
  • Sterile Prep (Betadine/Chlorohexidine): 3 sponges
  • Drapes
  • 1 % lidocaine (5 ml) skin, 1.5 % lidocaine with 1:200,000 epinephrine (5 ml) – test dose
  • Tuohy needle (17 or 18 gauge)
  • Needles (22 g smaller- skin and 18 gauge)
  • 3 ml, 5 ml, and 20 ml syringes
  • Filter needle
  • Line filter
  • Loss of resistance syringe (plastic or glass)
  • Epidural Catheter

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37
Q

What are the 4 types of epidural needles?
Which is the most common?

A
  • Tuohy (most common)
  • Hustead
  • Crawford
  • Weiss

S121

38
Q
  • A Tuohy needle has the ____ curvature @ ____ degrees.
  • What kind of needle tip is less likely to puncture the subarachnoid space?
A
  • most, 30 degrees
  • blunt tip

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39
Q

A Hustead needle has a ____ degree curve

A

15

S121

40
Q

A Crawford need is preferred when?
It has what degree curvature?

A
  • the catheter placement is dificult or the angel is steep (thoracic epidural).
  • 0 degrees

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41
Q

A Weiss needle has what curvature and what special feature?

A
  • 15 degree curvature
  • has WINGS!

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42
Q
  • What is epidural needle guage size?
  • A tuohy needle has a line that marks what?
  • Each mark on the needle is how many cm?
  • Total length to the hub?
  • Total length to window?
A
  • 17g or 18g
  • the marker marks the direction of the tuohy opening
  • Each line = 1cm
  • Total length to hub = 9 cm
  • Total length to window = 10 cm

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43
Q

Why have a stylet in the spinal needle?

A

prevents micro-embolisms

S112

44
Q

something about 2 gauges < needle

A

slide 123

45
Q

How far is the epidural catheter placed in the epidural space?

A

3-5 cm

slide 123

46
Q

what are the types of epidural catherers?

A
  • Multi-orificed (B)
  • Single (A)

slide 123

47
Q

Multi-orifice catheters have a lower incidence of inadequate anesthesia which means?

A
  • better distribution of local anesthesia spread

slide 123

48
Q

Higher incidence of inadvertent intravascular placement occurs with what type of catheter?

A
  • Multi-orifice

side 123

49
Q

what is the otimal epidural space length/depth?

A

3-5 cm

slide 123

50
Q

Benefits of coil reinforced catheters?

A
  • Stronger, less likely to shear when removed or placed
  • Softer tips reduces inadvertent SAB placement

slide 123

51
Q

label this epidural catheter

A

slide 123

52
Q
  • what are the characteristics of a plastic catheter?
  • what is a name of this type of catheter
A

Plastic Catheter Characteristics
* Easier to thread
* Inadvertent SAB puncture is a possibility
* Stiffer
* Less expensive

Name:
* Arrow Flex Tip Plus

slide 124

53
Q

how do you determine the distance of epidural catheter insertion?

A
  • Step 1: Measuring the Skin to the epidural space
    • After reaching the epidural space with the needle, subtract the visible needle length from the total length of the needle.
    • Example: If the total needle length is 9 cm (most of them are) and 4 cm is visible, the distance from the skin to the epidural space (depth of the epidural space) needle is 5 cm. (9 cm - 4 cm = 5 cm)
  • Step 2: Skin marking
    • The optimal epidural catheter depth should be between 3 to 5 cm in the space.
    • Let us use 5 cm as our optimal length/depth.
    • So, the catheter should be secured at 10 cm at the skin. The depth to the epidural space is 5 cm, add the catheter depth (5 cm) for a total of 10 cm at the skin.

slide 125

54
Q

Would you put a lumbar epidural in this patient?

A

yes, but take paramedian approach

slide 126

55
Q

Would you put a lumbar epidural in this patient?

A

yes, but take paramedian approach

slide 126

56
Q

what are the concerns with placing an epidural in a patient with a back tattoo?

A
  • There’s a risk that tattoo ink could be carried into the spine, potentially leading to inflammation (chemical arachnoiditis).
  • Since the 2002 report, most cases have shown that these epidurals do not cause neurological problems.

slide 127

57
Q

recommendations for placing an epidural in a patient with a back tattoo

A
  • Try to avoid placing the needle through tattooed skin.
  • If needed, avoid “nicking” the skin
  • Best to perform this within 5 months of the tattoo application for safety.

slide 127

58
Q

what are the steps for an epidural procedure?

A
  • Same as SAB (Timeout, positioning, monitors, sterile prep and drape, skin local)
  • Point the epidural tip upwards (opening should be cephalad)
  • Place the needle in interspinous ligament and withdraw stylet (BOUNCE)
  • Loss of resistance (LOR) with Air, Saline, or both
  • Continue advancing the needle until LOR (note depth to the epidural space)
  • Thread catheter
  • Advance the catheter 3-5 cm into epidural space
  • Withdraw the needle while advancing the catheter
  • Place catheter at correct skin marking
  • Test dose catheter with 1.5% lidocaine with epi (3 cc) [Intrathecal vs Intravascular?]
  • Secure with dressing (note cm at skin)
  • Establish a segmental blockade with the epidural dosing

slide 128

59
Q

what are important numbers to record [in cm] for an epidural procedure?

A
  • Depth to epidural space [distance for skin to epidural space]
  • Catheter marking at the skin
  • Catheter depth/length in the epidural space (# of cm in the space)

slide 128

60
Q

what are important techniques to utilize with epidural procedures?

A
  • Good Needle Control
  • Don’t advance needle without checking for resistance

slide 128

61
Q

2 ways to identify the epidural space

A
  • Loss of resistance
  • Hanging drop method

slide 129

62
Q

How to use the hanging drop method

A
  • A saline drop is placed at the hub of the needle and the needle (without syringe) is advanced
  • The epidural space is identified when the drop is “sucked” into the needle by the negative atmospheric pressure
  • Less precise and an old method

slide 129

63
Q

What is the purpose and composition of the test dose

A
  • Purpose: identify unintentional IV or SAB
  • Composition: 3mL of 1.5% Lidocaine mixed with epi (1:200,000) (will be on the test)

slide 130

64
Q

What 2 things do we watch for in the test dose of an epidural

What are the sx for IV placement?

A

Accidental IV Placement
* A jump in heart rate by 20% or more indicates a probable intravascular injection—replace the catheter (Tito says the HR change will be subtle because neuro changes happen before cardiac)

Accidental Spinal Injection
* Dense motor block within 5 min of a test dose
* Replace the catheter?

Other Symptoms:
* Ringing in ears (tinnitus)
* Metallic taste in mouth
* Numbness around the mouth

slide 130

65
Q

Special considerations for test doses

A
  • For Pregnant Women: Give the test dose after a contraction ends for clearer results - HR will increase with contractions
  • Patients on Heart Medications: A big increase in blood pressure (>20 mm Hg) could also mean the needle is in a blood vessel.

slide 130

66
Q

Plasma concentraion of LA with s/s of bad placement

A

Plasma concentration:
* 2-4: tongue numbness
* 4-6: Light-headedness
* 6-8: visual disturbance
* 8-10: Muscle twitches
* 10-12: unconsciousness
* 12-14: convulsions
* 16-18: coma
* 20-22: respiratory arrest
* 26-28: CVS depression

67
Q

Epidural Dosing

  1. What are the two ways to maintain an epidural?
  2. What is the initial dose per segment? What increment should it be given in?
  3. When should a TOP UP dose be give?
  4. How much TOP UP dose should be given ?
A
  1. Bolus and infusion
  2. 1-2mL/segment given in 5mL increments
  3. Give a top up dose before 2 segment regression.
  4. 50-75% of initial loading dose should be given as a top up.

slide 131

68
Q

Best practices for epidural anesthesia

A
  • Accurate dermatome assessment
  • Aspirate for blood or CSF
  • Injectate slowly in 5 ml increments
  • Monitor closely for 30 minutes (hypotension/unexpected dermatome spread)

slide 131

69
Q

Recommended “top-up” time in min from initial dose:
* Lidocaine
* Chloroprocaine
* Mepivacaine
* Bupivacaine and Ropivacaine

A
  • Lidocaine - 60 min
  • 2-Chloroprocaine - 45 min
  • Mepivacaine - 60 min
  • Bupivacaine and Ropivacaine - 120 min

slide 132

70
Q

6 common problems encountered with epidural placement

A
  1. CSF “wet tap”
  2. Paresthesia
  3. Can’t thread the catheter
  4. Aspirate blood: Good technique (slow aspiration)
  5. Positive test dose
  6. “False” positive test dose

slide 133

71
Q

Combined Spinal and epidural procedure steps

A

Same as epidural
* Once epidural space is located, a spinal needle is introduced through the Touhy until a “pop” is felt.
* Hold onto the spinal needle to prevent advancing the Tuohy into the subarachnoid space
* The stylet is removed from the spinal needle to observe CSF flow
* Inject spinal local anesthetic/analgesic
* Thread the epidural catheter

Fast process or the spinal will set-up in the sacral area without spreading cephalad
Catheter could enter dural puncture site

slide 136

72
Q

CSE picture for reference

A
73
Q

If you start a lumbar epidural at L4-L5, how many mL are needed for a T10 surgery?

A
  • 1-2mL per segment
  • Between L4 and L5[ don’t count L4]
    • segments: L3, L2, L1, T12, T11, T10 = 6 segments
  • administer 6-12mL of LA

Lecture

Principles of Anesthesia I 2024 (4 decks)

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