Spinal and Epidural Flashcards
What is the ligamentum flavum also known as?
- “yellow ligament”
Ligamentum flavum extends:
-extends from foramen magnum to sacral hiatus
Pia mater:
-adheres to the spinal cord
Dura mater:
- begins at foramen magnum and ends at S2
- abuts arachnoid mater (subdural space)
Arachnoid mater
- physiological barrier for drugs moving btw the epidural space and spinal cord
- abuts pia mater- gives rise to subarachnoid space
Subarachnoid Space:
- contains CSF- cont with cranial CSF
- houses spinal nerve roots and rootlets
Spinal cord extends from:
-foramen magnum to conus medullaris (terminates at L1 or L2)
Termination of dural sac occurs at what level?
S2
What is a dermatome?
-the area of skin innervated by a spinal nerve and its segment
What is a segment?
- rootlets of a single spinal nerve coming from the spinal cord
CSF is found in what space?
-subarachnoid space
CSF is produced by:
-choroid plexus
Where is spinal anesthesia delivered?
- subarachnoid space
Where is epidural anethesia delivered?
- epidural space
Principal site of a neural blockade is:
- the nerve root
T/F: Blockade can occur at any point AND all points along the neural pathways extending from the site of the drug admin to the interior of the cord.
True
In a centroneuraxial blockade what fiber types are blocked?
- nociceptive
- motor
- proprioceptive
- autonomic
The purpose of the centroneuraxial blockade is to block?
- the nociceptive impulses
- but ANS and motor are blocked too
Considerations for regional techniques:
- anatomy
- age
- pregnancy
- pathophysiology
What procedures would you give GA and an epidural/SAB?
- major abdominal procedure
- lower extremity vascular cases
When would a SAB/epidural block be indicated for analgesia?
- postoperative
- labor and delivery
Major absolute contraindication for a neuroaxial block
-patient refusal
Cardiovascular effects of neuroaxial blocks depend on:
- spread and blockade of the ANS
What changes would be seen if CV effects occurred with a neuroaxial block?
- decreased BP, HR, MAP, CO and SVR
- decreased CO is typically d/t venous dilation/pooling
Major pulmonary side effects of a neuroaxial block:
- as block ascends, accessory muscle paralysis occurs
- perception of ineffective breathing and decreased ability to cough
Phrenic nerve associated with what level of the spine? What is the first sensation that this nerve may be seeing LA?
- C3 to C5
- pinky finger tingling may indicate block is ascending
Effect of neuroaxial block on GI/renal:
- hyperperistalsis
- N/V
- bladder dysfunction
Effect of neuroaxial block on metaolic/endocrine:
- decrease stress response r/t surgery
- decrease cortisol release
- catecholamine release may be decreased
Lateral decubitus position:
- forehead to knees
Which SAB needle will be more likely to cause a Postdural Puncture Headache- Sprotte (pencil point needle) or Quincke (cutting needle)?
- Quincke (cutting needle)
Most common technique for a spinal block?
- median approach
Why would you do a paramedian approach for SAB?
- for pts who cannot adequately flew b/c of pain or whose ligaments are ossified
- spinal needle is pace 1.5 cm laterally and caudad
What layers do you go through to place and epidural?
- skin
- subq tissue
- supraspinous ligament
- infraspinous ligament
- ligamentum flavum
- EPIDURAL SPACE
What layers do you go through to place a SAB?
- skin
- subq tissue
- supraspinous ligament
- infraspinous ligament
- ligamentum flavum
- (epidural space)
- dura mater
- (dural space)
- arachnoid mater
- SUBARACHNOID MATER - CSF
Landmarks for SAB?
- identify superior iliac crests and L4
Epidural placement uses what kind of technique?
- loss of resistance technique (air filled glass syringe)
The epidural space is located directly after which ligament?
- ligamentum flavum
Typically, how far is the ligamentum flavum from the skin in a normal sized adult?
- 4 to 6cm
How much do you advance your epidural catheter once in the epidural space?
- 2 to 3 cm
For SAB/epidural needle placement position the needle bevel needs to be inserted:
- needle bevel is inserted parallel to longitudinal fibers
In PARTURIENTS the epidural catheter is advanced:
- 4 to 6 cm
The density of a solution to the density of another substance.
Baracity
What is hyperbaric solution mixed with and why? What is the SG?
- dextrose
- allows LA to settle in dependent areas
- SG greater than 1.11
What is hypobaric solution mixed with and why? What is the SG?
- sterile water
- allow LA to go upward (broken right hip ex)
- SG less than 1.005
What is isobaric solution mixed with? What is the SG?
- mixed with CSF
- less than 1.006
Factors influencing block height
- dose
- site of injection
- baracity
- position of patient
When can a patient go to the floor after a spinal?
- PACU to the floor after 4 dermatome regression less than T10, stable and comfortable
When can a patient be discharged home after a spinal?
SDS to home after ambulation without orthostatic changes, + void
Delivery of LA to the epidural space via injection through the sacral hiatus
- Caudal block
Major complications of spinal/epidural/caudal blocks:
- hypotension
- sudden cardiac arrest
- post dural puncture HA
- epidural hematoma
Post dural puncture headache, treatment?
-epidural blood patch, bedrest, hydration, oral analgesics, epidural saline injection
Why does post dural puncture HA occur?
- d/t intracranial pressure with compensatory cerebral vasodilation
Epidural hematoma is primarily caused by:
- a coagulation defect
- can cause paralysis
S/S of LA toxicity:
- neuro changes
- seizure followed by CNS depression, apnea, hypotension
- transient radicular irritation
- cauda equina syndrome
Dural mater/sac extends from where to where?
-foramen magnum to S2
T1 to T4 is known as the:
-cardioaccelerators, unopposed vagal response
The continuous catheter technique for epidural placement, what needle is used?
Tuohy needle
Specific gravity of CSF
-1.004 to 1.008
What is the primary cause of an epidural hemotoma?
-coagulation defect
