APEX - Neuraxial Flashcards
Each vertebra can be divided into what two segments?
Anterior and Posterior segment
What two structures join the anterior and posterior segments of the vertebra and form the vertebral foramen?
The laminae and pedicles
What part of the vertebra contains the spinal cord, nerve roots, and epidural space?
The vertebral foramen
How do the spinal nerves exit the vertebral column?
The spinal nerves exit the vertebral column by way of the intervertebral foramina
The transverse processes project (in what direction), while the spinous process projects (in what direction)
The transverse processes projects LATERALLY, while the spinous process projects POSTERIORLY.
The cervical and thoracic spinous processes angle is in what direction?
The cervical and thoracic spinous processes angle is a CAUDAL direction. This requires a more cephalad approach with the needle.
Lumbar spinous processes projects in what direction?
Lumbar spinous processes projects in a POSTERIOR direction. This makes access to the epidural and intrathecal spaces easier.
The supraspinous ligament joins what part of the vertebra
The tips of the spinous processes
How does the Interspinous Ligament connect the vertrebras?
The Interspinous Ligament travels adjacent to and joins the spinous processes
What is the significance of the Ligamentum Flavum?
Piercing the ligamentum flavum contributes to the loss of resistance when the needle enters the epidural space.
What ligaments will you pierce using a Midline approach?
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
What ligament will you pierce using a paramedian approach?
Ligamentum flavum
The paramedian approach bypasses the suprasponous and interspinous ligaments.
What space is between the Ligamentum flavum and dura mater?
Epidural space
What space is between the dura mater and the arachnoid mater?
Subdural space
What space is between the Arachnoid mater and Pia Mater?
Subarachnoid space
What are the layers of the meninges? (In order from outside in)
Dura
Arachboid
Pia
DAP
What is the subdural space?
The potential space between the dura matter and the arachnoid mater
What is the subarachnoid space?
This space is just past the arachnoid mater. It contains CSF, nerve roots, rootlets, and the spinal cord. This is the target when performing a spinal anesthetic.
What is the Dura mater?
- It is the first meningeal layer.
- After the needle advances through the epidural space, it comes into contact with the dura matter.
- The Dura matter is a rough fibrous protective shield that protects the spinal cord.
What is the arachnoid mater?
- A think layer of connective tissue that neighbors the dura mater.
- The second meningeal layer
What is the Pia Mater?
- This is the external covering of the spinal cord.
- This is the meningeal layer.
How many vertebrae does the sacrum consist of?
5 Vertebrae
At what level of the spinal column does the superior iliac spines coincide with?
S2
The sacral hiatus is cover by what ligament?
It is covered by the sacrococcygeal liagment
How many paired spinal nerves does the spinal cord have?
31 paired spinal nerves
What is a dermatome?
A dermatome is an area of skin that is innervated by a dorsal nerve root from the spinal cord.
What is the site of action for spinal anesthesia?
In the subarachnoid space, the primary site of local anesthetic action is on the myelinated preganglionic fibers of the spinal nerve roots.
What is the site of action for an epidural anesthesia?
LA in the epidural space must first diffuse through the dural cuff before they can block the nerve roots.
With spinal anesthesia, which fibers are blocked first, second, and last?
Autonomic fibers are blocked first (B fibers)
Sensory fibers are blocked second (C and Adelta)
Motor neurons are blocked last (A g, A b, Aa)
With neuraxial anesthesia, how is bradycardia caused?
Bradycardia is caused by the blockage of the preganglionic cardioaccelerator fibers at T1-T4, this is causes a relative increase of parasympathetic tone.
With neuraxial anesthesia, what causes apnea?
Apnea is usually the result of cerebral hypoperfusion, it is NOT the result of the phrenic nerve paralysis or high concentrations of local anesthetics in the CSF
For neuraxial anesthesia, if a patient is on aspirin, what do you do?
Proceed with neuraxial anesthesia if:
patient has normal clotting mechanism and
patient is not on any other blood thinning agents
For neuraxial anesthesia, if a patient is on Eptifibatide (Integrilin), what do you do?
Hold the medication 8 hours before the block placement
For neuraxial anesthesia, if a patient is on abciximab (Rheopro), what do you do?
Hold the medication 1-2 days before the block placement
For neuraxial anesthesia, if a patient is on Clopidogrel (Plavix), what do you do?
Hold the medication for 7 days before the block placement
For neuraxial anesthesia, if a patient is on Ticlopidine (Ticlid), what do you do?
Hold the medication for 14 days before the block placement
For neuraxial anesthesia, if a patient is on SQ heparin for DVT prophylaxis, what do you do?
Proceed with neuraxial anesthesia if:
Patient has normal clotting mechanism and
Patient is not on other blood thinning drugs
For neuraxial anesthesia, if a patient is on IV heparin, what do you do?
Hold for 2-4 hours before the block placement.
Hold for 1 hour after the block placement.
Hold for 2-4 hours after the indwelling catheter has been removed.
For neuraxial anesthesia, if a patient is on Enoxaparin, what do you do?
Hold 12 hours for the prophylactic dose (1x daily)
Hold for 24 hours for the therapeutic dose (2x daily)
Hold 12 hours before removing indwelling catheter
Hold 2 hours after the indwelling catheter has been removed.
For neuraxial anesthesia, if patient is on Warfarin, what do you do?
Hold for 5 days before the block placement.
Can remove catheter if INR less than 1.5
For neuraxial anesthesia, if patient is on Garlic, Ginko, Ginseng, Glucosamine, or Chondroitin, What do you do?
Proceed with neuraxial anesthesia if patient is not on other blood thinning drugs
Where is the conus medullaris in adults and children?
Adults L1-L2
Infant L3
What is the Cauda Equina?
A bundle of spinal nerves extending from the conus medullaris to the dural sac
Where is the Dural sac?
Adults S2
Infant S3
The subarachnoid space terminates at the dural sac
What is the Filum Terminale?
This extends from the conus medullaris to the coccyx
What are the S/S of Cauda Equina Syndrome?
Bowel and bladder dysfunction, sensory deficits, weakness, and/or prarlysis
What causes Cauda Equina Syndrome?
Neurotoxicity is the result of exposure to high concentrations of local anesthetics
What causes transient neurologic symptoms?
patient positioning, stretching of the sciatic nerve, myofascial strain, and muscle spasms. It is highly unlikely that neurotoxicity causes TNS
What are the S/S of transient neurologic symptoms?
severe back and butt pain that radiates to both legs.
In general it develops within 6-36 hours and persist for 1-7 days.
