Mod VII: EPIDURAL ANESTHESIA Flashcards Preview

8362 T&T Exam 2 > Mod VII: EPIDURAL ANESTHESIA > Flashcards

Flashcards in Mod VII: EPIDURAL ANESTHESIA Deck (48)
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When a local anesthetic (may also add opioid, epi, bicarb) is injected into the epidural space, initially blocking spinal nerve roots and then diffusing into the subarachnoid space creating a conduction blockade of the spinal nerves, this technique is known as:

Epidural Anesthesia (EA)

 

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Epidural Anesthesia (EA)

Placement of a flexible catheter into the epidural space via needle, remains in place for

the anesthetic and dosing is intermittent/continuous

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Epidural Anesthesia

Indications for EA

Sole anesthetic for operations below the umbilicus

Lower extremities (esp. hip and knee)

Pelvis

Perineum

Lower abdomen

Obstetrical procedures (very popular in this population)

Adjunct anesthetic or post-op pain control

Upper and lower abdominal procedures

Thoracic procedures

Treatment of Acute / Chronic pain

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Epidural Anesthesia (EA)

Advantages: (compared to GA)

Similar to spinal anesthesia!!!

Awake patient, reflexes

Decreased stress response

Decreased cost

Early ambulation, eating, less PONV

Decreased blood loss

Postoperative analgesia

Flexibility

Increased patient satisfaction

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Epidural Anesthesia (EA)

Disadvantages

Technically more difficult to place

Takes longer to set up than SAB or GA

Less dense block than SAB

Catheter may migrate from epidural space

Less reliable (higher failure rate or patchy block)

Greater chance for LA toxicity

Infection

Epidural hematoma

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Epidural Anesthesia (EA)

Absolute Contraindications

 

Inadequate resuscitation drugs or equipment

Patient refusal or uncooperative

Uncorrected coagulopathies

Infection at site of injection

Septicemia

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Epidural Anesthesia (EA)

Relative Contraindications

Hypovolemia

Fixed CO states

Anatomical deformities of spine

Neurological disease

Increased ICP

Chronic back pain

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Epidural Technique

Most components are very similar to spinal administration - including:

Patient position, prep, drape, local

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Epidural Technique​

Major difference in technique between epidural and spinal are:

Introduction of tuohy needle

Identification of epidural space

Threading the catheter

Removal of tuohy needle

Test dose of catheter

Securing catheter for dosing

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Epidural Technique​

Technique for dentification of epidural space

Loss of resistance technique

(to be demonstrated in lab)

 

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Epidural Anesthesia (EA)

Dosing Techniques

Test Dose

LA solutions should be injected in increments of 3-5 ml every 3-5 minutes (always aspirate prior to injecting) and titrate to desired anesthetic level

Block should set up in about 20 min.

When block recedes 1-2 dermatone levels, re-dose with 30-50% of initial dose to maintain initial level of anesthesia (if continuous infusion, increase rate or concentration)

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Epidural Anesthesia (EA) - Dosing Techniques

How should LA solutions be injected?

In increments of 3-5 ml every 3-5 minutes

Always aspirate prior to injecting

Titrate to desired anesthetic level

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Epidural Anesthesia (EA) - Dosing Techniques

Block should set up in about

20 min.

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Epidural Anesthesia (EA) - Dosing Techniques​

What could you do When block recedes 1-2 dermatone levels in order to maintain initial level of anesthesia ?

Re-dose with 30-50% of initial dose to maintain initial level of anesthesia

If continuous infusion, increase rate or concentration

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Epidural Anesthesia - Assessment of block

Three classes of nerves blocked:

Autonomic nervous system

Sensory nerves

Motor nerves

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Epidural Anesthesia - Assessment of block

Dermatomes

Dermatomes

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Epidural Anesthesia (EA)

Factors influencing spread of LA in the epidural space

Injection site (Most important determinant)

Drug Volume

Drug Dose

Drug concentration

Patient position

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Factors influencing spread of LA in the epidural space

Injection site - Epidural anesthesia produces a segmental block that spreads in which directions from site of injection?

Caudally & Cranially

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Factors influencing spread of LA in the epidural space

Caudal spread (or is it caudal injection?!) of LA restricted to which dermatomes?

Sacral and lower lumbar dermatomes

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Factors influencing spread of LA in the epidural space

Under which condition can Caudal spread (or is it caudal injection?!) of LA reach Lower thoracic levels? what's a possible disadvantage of this approach?

Larger volumes (30ml)

Block is “patchy” and short lived

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Factors influencing spread of LA in the epidural space

Which dermatomal levels can be reached with Lumbar site injection/spread?

 

Midthoracic levels (T4-T6) with 20ml

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Factors influencing spread of LA in the epidural space

Lumbar site injection/spread can reach caudally with only what volume of LA?

only 10mL of LA

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Factors influencing spread of LA in the epidural space

Thoracic injection/spread

Produces a symmetric segmental block

With mid to upper thoracic injection sites, reduce dose by 30-50% to prevent excessive cephalad spread

Not feasible to produce surgical anesthesia in lower lumbar region with this site

 

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Factors influencing spread of LA in the epidural space

With mid to upper thoracic injection sites, reduce dose by what % ? - why?

30-50%

To prevent excessive cephalad spread

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Factors influencing spread of LA in the epidural space

Thoracic injection/spread Not feasible to produce surgical anesthesia in which region?

Lower lumbar region

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Factors influencing spread of LA in the epidural space

Drug Volume - Increase the volume, what happens?

...

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Factors influencing spread of LA in the epidural space

Drug Volume - Suggested volumes of LA per spinal segment spread (how many interspaces you need LA to spread) - Cervical & Thoracic epidural vs Lumbar epidural?

Cervical & Thoracic epidural = 0.7-1.0 ml per segment (~10ml)

Lumbar epidural =  1-2  ml per segment (~15-20ml)

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Epidural Anesthesia

Factors influencing spread of LA in the epidural space

Drug Dose

Drug concentration

Patient position

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Epidural Anesthesia

Factors influencing duration

Local anesthetic drug (principle determinant of duration)

Common LA used (Table 56-6)

Shortest duration: chloroprocaine

Intermediate duration: lidocaine, mepivacaine

Longest duration: bupivacaine, ropivacaine, etidocaine

LA’s exhibit different effects of intensity and duration of sensory and motor block

Etidocaine : most intense motor block vs. sensory

Bupivacaine: more intense sensory block vs. motor

Dose (concentration)

Increasing dose = increased duration and intensity

Addition of epinephrine, sodium bicarbonate

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Factors influencing duration - Local anesthetic drugs

Common LA used

(Table 56-6)