Regional Exam II Flashcards
Injection location
(spinal vs. epidural)
spinal - lumbar only
epidural - anywhere
duration of block
(spinal vs. epidural)
spinal - brief
epidural - longer
Which has a better quality of block, spinal or epidural?
spinal
sacral hiatus
unfused opening between S4 and S5
T7-T8 Landmark
lower limits of scapulae
C7 landmark
bony knob at base of neck
L2 Landmark
terminal point of 12th ribs
L4 Landmark
Iliac crest
S2 Landmark
posterior iliac spines
what connects the epidural space with the paravertebral space?
foraminae
Maximal depth of epidural space
6 mm at L2
(only 4-5 mm in the midthoracic area)
plica mediana dorsalis
connect dura mater to the ligamentum flavum
(may not even exist)
(5) complications to discuss with patient
- nerve damage
- bleeding
- infection
- headache
- failed block
Which type of block would be performed in a perineal surgery?
spinal
One should probably not attempt a spinal above _____
L3 - L4 interspace
Which type of needles are more likely to cause PDPH?
beveled
(Quincke)
Two types of Pencil-point Spinal Needles
Whitacre and Sprotte
Which spinal approach is independent of patient flexion?
Taylor
- star 1 cm medial and caudal to PSIS
- advance cephalad at 55o with medial orientation
Which spinal approach is best suited for narrow interspaces or difficulty with flexion?
Paramedian
Level and duration of spinal are primarily determined by _____
baricity, contour of spinal canal, and patient position
Epinephrine in spinals
vasoconstricts, decreasing the spread, and has some alpha-2 analgesia
Tetracaine in spinals
major vasodilation
(vasopressors have a profound effect)
Bupivacaine in spinals
decreases spinal and dural blood flow
Dose of Lidocaine for spinals
60-75 mg
Dose of Chloroprocaine for Spinals
40-60 mg
Dose of Bupivacaine for spinals
5 - 20mg
Which one is more profoundly affected by vasoconstrictors?
Tetracaine or Bupivacaine
Tetracaine
Opiates in spinals
affect the dorsal horn
usually 25 ug of Fentanyl
Dose of Tetracaine for spinals
5 - 20 mg
Sensory level for Hemorrhoidectomy
S2 - S5
Sensory level for Foot surgery
L2 - L3
Sensory level for lower Extremities
L1 - L3
Sensory level for Hip, TURP, or vaginal delivery
T10
Sensory level for Lower abdomen or Appendectomy
T6 - T7
Sensory level for upper abdomen or C-section
T4
Anything above ____ inhibits SNS to the GI tract
T5
First-line drug to treat hypotension in Spinals
Ephedrine
Blood Patch
15 - 20 mL
injected at or below the site, as the blood will travel cephalad
Warning sign of hypotension and stroke during spinal
nausea
Hypotension in Spinals
occurs in 1/3 of patients
initially due to decreased SVR
Most common epidural needle
Tuohy
Most common approach for lumbar epidural
midline
Two techniques to identify epidural space
loss of resistance
or
hanging drop
Test dose
3 cc of 1.5% lidocaine with 1:200,000 Epi
Caudal blocks
epidural injections placed through the sacrococcygeal ligament and sacral hiatus
Sacral Hiatus is absent in ____% of patients
10
Difference between Lumbar and Thoracic epidurals
Lumbar tends to flow cephalad due to negative intrathoracic pressure, whereas thoracic stays in place
What will cause spread of local in epidurals?
negative intrathoracic pressure
Intermediate duration LA
lidocaine
Which LA is not effected by Epinephrine?
Bupivacaine
Epinephrine in Epidurals
prolongs duration
(especially if chloroprocaine or lidocaine)
- may accentuate the fall in blood pressure
Sodium Bicarbonate with Epidurals
promotes more rapid onset
If epidural anesthesia has “partially failed, “ consider ____
injecting small doses of chloroprocaine
Which LA has a higher risk of absorption or intravascular injection?
Bupivacaine
Major site of action for an epidural
nerve roots
Neuraxial blocks results in a sympathectomy ____ dermatomes above the sensory block
2 - 6
Bainbridge Reflex
stimulation of right atrial stretch receptors leads to vagal afferent stimulation of medulla and subsequent inhibition of parasympathetic activity
(increase HR)
(3) mechanisms that effect heart rate
- bainbridge reflex
- direct effect on the SA node elicited by atrial stretching
- anesthesia of T1-4 cardioaccelerator fibers
Cardiovascular effects of Neuroaxial Anesthesia
arterial and venous dilation
and
decreased preload and HR
Which drug should be considered in parturients instead of Epi or ephedrine
phenylephrine
Risk of headache after accidental dural puncture with an epidural needle is ____
about 50%
(6) Risk Factors for PDPH
- beveled needle (quinke)
- larger needle
- female
- pregnant
- young
- history of headaches
Order of block sensitivty
temperature > SNS > pain > touch > motor
(first to last to go)
Anesthetic effects of central blocks
- decrease MAC
- produce sedation
- potentiate hypnotics
location of cardioaccelerators
T1-4
Epidural with epinephrine seems to cause _____ hypotension than without Epi
more
What are two major factors affecting block height?
baricity and patient position
Spinal blocks wear off in a ______ direction
cephalad to caudad
(thus sacral lasts longer than thoracic)
Higher blocks usually wear off _____ than lower blocks
faster
_____ agonists can prolong a spinal block
adrenergic
Reduce anesthetic dose by _____ if working on upper dermatomes
30-50%
(rksk of cephalad spread is increased)
Caudal is more similar to an epidural or spinal?
epidural
Spinal is injected into the ___
subarachnoid space
subarachnoid space is a continuous space that contains _____
CSF, spinal cord, and conus medullaris
Where does the subarachnoid space end?
conus medullaris at the sacral hiatus
termination of spinal cord
usually at L1
(L3 in pediatrics)
Dorsal (posterior) roots are responsible for ____
sensory blockade
Anterior (ventral) roots are responsible for _____
motor blockade
total CSF in adults
100 - 150 mL
CSF volume in subarachnoid space
25 - 35 mL
specific gravity of CSF
1.0003 - 1.0006
Supraclavicular Nerves
branches of the superficial cervical plexus (C3-C4)
- provides cutaneous innervation at the shoulder
Suprascapular Nerves
C5 and C6 provides sensory innervation to posterior/superior shoulder and anterior axilla
Intercostobrachial Nerves
T2
- often used to treat tourniquet pain
Axillary Block

Infraclavicular Block

Interscalene Block

Supraclavicular Block
