Locals/Regional Anesthesia 1 Flashcards
central neuraxial blocks, anatomy, physiology, mechanisms, & complications
What are the 3 main bony parts of the vertebrae?
- vertebral body
- spinous process
- bony arch
What is the spinous process formed by?
Formed by the joining of each lamina
The bony arch is made up of what 3 major parts?
lamina
processes
pedicles
Which position are the lamina located? How many?
2 lamina posterioly
Which position are the processes located? How many?
2 transverse processes
Which position are the pedicles located? How many?
2 anterior pedicles
The IV foramen contains what?
Spinal cord
CSF
How many vertebrae are in the spinal cord?
33 vertebrae
How many vertebrae are in the spinal cord if fused vertebrae are counted as 1?
26 vertbrae
How many cervical vertebrae?
7 vertebrae
What are the smallest vertebrae?
cervical
How many thoracic vertebrae?
12 vertebrae
How man lumbar vertebrae?
5 vertebrae
What are the largest vertebrae?
Lumbar
How many sacral vertebrae? Are they fused? Are they considered 1 vertebrae?
Yes, 5 fused vertebrae but may be considered 1 vertebrae
How many coccygeal vertebrae? Are they fused? Are they considered 1 vertebrae?
Yes, 4 fused vertebrae but may be considered 1 vertebrae
Which spinal processes have a horizontal angle?
Cervical
Low thoracic
lumbar
Which spinal processes have a caudad angulation?
thoracic
Do ligaments increase stability and elasticity?
Yes
What does the supraspinous ligament connect?
Connects the tips of the spinous processes from sacrum to T7
What does the interspinous ligament connect?
Connects the posterior spinous processes & fills gap
What is considered the thickest ligament?
Interspinous
What does the ligamentum flavum connect?
Connects the lamina of the adjacent vertebrae
Which ligament is the primary supportive ligament of the vertebral column?
Anterior/posterior longitudinal ligament
What does the Anterior/posterior longitudinal ligament bind?
Binds vertebral bodies
_____ angles determine needle approach angles
VERTEBRAE angles determine needle approach angles
What is the key surface landmark for C7-T1?
Vertebral prominens
What is the key surface landmark for T7
Inferior scapula
Where does Touffier’s/intercristal line correlate with?
Illiac crest
The illiac crest are located at what vertebrae?
top of L4
What is the key surface landmark for S2?
Posterior/ Suprior illiac spines
Where is the foramen magnum located?
L1-L2
Where does the dural sac terminate?
S2
Where does the epidural space start and end?
Foramen magnum to the sacral hiatus
Where does the spinal cord terminate in adults?
L1-L2
Where does the spinal cord terminate in children? What implication does this have for completeing blocks?
L3, you must start your block lower than that of adults
What is the order of spinal covering from inner to outer?
pia mater > arachnoid > subarachnoid > dura mater > epidural space
Where is the pia mater located?
adheres to the SC and nerves
Where is the arachnoid located?
between the pia mater and dura mater
Where is the subarachnoid loacated?
between the arachnoid and pia mater
What does the arachnoid hold?
CSF
What is considered the toughest outer membrane
dura mater
What is the epidural space and where is it located?
- a potential space between dura mater and ligamentum flavum
How many nerve root pairs are there?
31 pairs
Group these words together: posterior, ventral, anterior, dorsal
- ventral = anterior
- dorsal = posterior
Is dorsal motor or sensory? Ventral?
- dorsal = sensory
- ventral = motor
Gray matter provides how many cc/100 gm/min of blood to the brain?
80 cc/100 gm/min
White matter provides how many cc/100 gm/min of blood to the brain?
20 cc/100 gm/min
What is the avg amount of blood supply to the brain from the SC?
50 cc/100 gm/min
Are blood flow and auto regulation to the SC similar to the brains?
Yes, slightly less blood flow
Where does the blood supply for the SC come from?
1 anterior spinal artery
2 posterior spinal arteries
Is CSF an ultra filtrate?
No
What lytes are associated with CSF?
High Na
Low K, Ca, Bicarb, Glu
What is normal appearance of CSF?
clear, colorless, water-like solution
Why could CSF be yellow/xanthochromia?
post SAH
Why could CSF be hazy or turbid?
leukocytes or protein
Is it normal to see some blood in CSF which quickly clears while doing a block?
Yes
What does the monroe kelly doctrine say in regards to CSF?
brain tissue, blood and CSF work together to keep normal ICP
What is normal ICP?
5-15mmhg
Can you do a subarachnoid block if the patient has increased ICP?
NO
What is a sensory dermatome?
Specific area of skin innervated by a single spinal nerve
What is the sequence of clinical anesthsia blocking?
- symp blocking w/peripheral vasodilation & skin temp elevation
- loss of pain & temp sensation
- loss of proprioception
- loss of touch and pressure sensation
- motor block
What is first to get blocked? What is last?
SNS blocked first
Motor blocked last
What is first to come back when block wears off? What is last?
Motor back first
SNS back last
What is the order in which nerve fibers are blocked from 1st to last?
B fibers > C & A delta fibers > A gamma fibers > A beta fibers > A alpha fibers
Which fibers are preganglionic? Which are post ganglionic?
- preganglionic B fibers
- postganglionic C and A delta fibers
What are the zones of differential blockade?
ANS > Sensory > Motor
How many dermatomes must be blocked in order to have a sympathetic block?
Approximately 2 dermatomes above the sensory level
How to determine a sensory block?
determined by loss of normal sensation (like pinprick or cold) which is 2 levels above motor
Which nerve is hardest to block?
Motor
What is involved in patient prep & consent?
- explaination risks and agreeement
- IV access
- Fluids (can co treat)
- sedation (sometimes)
What is the preferred position for spinals?
sitting because it allows for easier visualization of anatomy
What is involved in proper patient sitting positioning for a spinal?
- no torquing (remain straight)
- dangle or cross legged
- chin to chest
- arms resting on knees
What are the 2 approaches to inserting a spinal/epidural?
- midline
- paramedian
Which insertion technique is most common?
midline
Why would you use a paramedian insertion approach?
For older individuals with calcified interspinous
For what spinal location can you use the paramedian approach?
with lumbosacral spinals
How would you do the paramedian approach?
1 cm down, 1 cm lateral
What is the order in which the needle punctures the layers during a SPINAL in the medial approach?
Skin
Sub Q
Supraspinous
Interspinous
Flavum
Epidural space
Dura mater
Subdural space
Arachnoid
Subarachnoid
Which layer is bypassed in the paramedian insertion approach?
Supraspinous ligament
What is the order in which the needle punctures the layers during an EPIDURAL?
Skin
Sub-Q
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space
How deep is the epidural space?
4-6 cm depth
When is the Taylor’s approach used for SAB?
In the event of severe arthritis
What approach is used for the Taylor’s Approach?
paramedian technique at L5-S1