Exam 1 - Neuraxial Principles (Part 1) Flashcards
What are the two components of Central Neuraxial Anesthesia?
Which one is harder to perform?
- Spinal Anesthesia
- Epidural Anesthesia (This one is harder to perform, it takes skills.)
Will you expect to see CSF during epidural blocks?
No. CSF should not be expected in epidural blocks.
If CSF is present, you have entered into the subarachnoid space.
CSF is expected in spinal/intrathecal blocks.
What ligaments will the needle pass through to get to the epidural space?
- Supraspinous Ligament
- Interspinous Ligament
- Ligamentum Flavum
Spinal Anesthesia is the injection of local anesthetic (LA) into ___ space.
- Subarachnoid
also called a subarachnoid block (SAB) or intrathecal.
Describe the onset between a spinal block and an epidural block.
Spinal Block: Rapid Onset (5 min)
Epidural Block: Slow Onset (10-15 mins)
Describe the spread of LA between a spinal block and an epidural block.
Spinal Block: Higher than expected; may extend extracranially.
Epidural Block: As expected, can be controlled w/ volume of LA.
Describe the nature of the block between a spinal block and an epidural block.
Spinal Block: Dense
Epidural Block: Segmental
Describe the motor block between a spinal block and an epidural block.
Spinal Block: Dense motor block
Epidural Block: Minimal
Is hypotension more likely to occur between a spinal block or an epidural block?
Spinal Block
What LA discussed in class is used for a “walking” epidural?
A. chloroprocaine
B. ropivacaine
C. lidocaine
D. bupivacaine
B. Ropivacaine
Ropivacaine provides a very segmental block
What are your cardiac accelerator nerves?
T1 - T4 spinal nerves
What term was used in class to describe antagonized sympathetic nerve fibers secondary to local anesthetics?
- Sympathectomy
This usually results in hypotension and bradycardia.
Differentiate the duration of action between a spinal block vs an epidural block.
Spinal: Limited and fixed (one-shot)
Epidural: Unlimited (Catheter in place w/ LA infusion)
Differentiate the level of placement between a spinal block vs an epidural block.
Spinal Block: L3-L4, L4-L5, L5-S1
Epidural Block: Any Level
How many attempts are permitted for a spinal/epidural block?
- Three
Differentiate the dosing between a spinal block vs an epidural block.
Spinal Block: Dose-base
Epidural Block: Volume-base
What is the max amount (volume) of LA for a spinal block vs epidural?
Spinal Block: 3 mL
Epidural Block: 20 mL
Differentiate the concentration of LA between a spinal block vs an epidural block.
Spinal Block: Concentrated and fixed
Epidural Block: Varies
Differentiate the LA Toxicity between a spinal block vs an epidural block.
Spinal: No
Epidural: Yes (Higher risk of LA entering the bloodstream due to bilateral veins on the spine.)
Which LA discussed in class is the most sensitive to the heart?
- Bupivacaine
What should be done during a Bier Block procedure if IV Bupivacaine is accidentally administered instead of Lidocaine?
- Leave the tourniquet in place and let the bupivacaine be absorbed.
- Do not deflate the cuff unless you want V-tach/ V-fib.
Differentiate the gravity influence between a spinal block vs an epidural block.
Spinal Block: Yes, there will baricity
Epidural: No, unless the needle punctures the dura (“wet tap”).
Differentiate the manipulation of dermatome spread after dosing between a spinal block vs an epidural block.
Spinal: Positional Change depending on baricity (Iso, Hyper, Hypobaric)
Epidural: Incremental dermatome spread based on volume. 1-2 mL per segment.
The use of neuraxial anesthesia can reduce these 6 factors.
- Bleeding
- Narcotic usage
- Postop Illeus
- Thromboembolic events
- PONV
- Respiratory complications
What are the other benefits of Neuraxial Anesthesia?
- Great mental alertness
- Less urinary retention
- Quicker to eat, void, ambulate
- Quicker PACU discharge (use Lidocaine)
- Preemptive anesthesia
- Blunts stress response from surgery
What are the indications of spinal anesthesia?
- Surgical procedures involved with Lower abdomen, Perineum, and Lower extremities (Knees/Hips)
- Cesarean Delivery (for elective and stat cases only)
What anesthesia would be indicated if the surgeon needs the patient to be still?
- General Anesthesia
Important to communicate with surgeon about the plan of care.
What anesthesia would be indicated if there is an emergency Cesarean delivery?
- General Anesthesia (Rapid Sequence Induction)
What are absolute contraindication of spinal anesthesia?
- Coagulopathy (risk of epidural hematoma)
- Sepsis
- Patient refusal/ cooperation/ mental competency/ age/ lack of informed consent
- Evidence of dermal site infection
- Hypovolemia (Already prone to sympathectomy)
- Pre-existing spinal cord disorder (intraspinal mass)
- Valvular disease (Aortic/Mitral Stenosis)
What is the problem with aortic stenosis when performing spinal anesthesia?
- Decrease SVR resulting in hypotension
Do not perform spinal anesthesia if the patient has severe aortic stenosis <1.0 cm2
Absolute contraindication coagulopathy lab values for spinal anesthesia.
INR
Platelets
- INR > 1.5
- Platelet < 50-100K (consider trends)
What are relative contraindications of neuraxial anesthesia?
- Deformed spinal column (ie: kyphoscoliosis)
- Pre-existing disease of the spinal cord (MS)
- Chronic HA/ backache (take a baseline assessment)
- Inability to perform SAB after 3 attempts
How many vertebrae does a human have?
- 33