Regional Anesthesia Flashcards
1
Q
How long does it take for the spinal cord to go from L3 in the newborn to L1?
A
20-24mos
2
Q
Which ligament binds the epidural space posteriorly?
A
ligamentum flavum
3
Q
Where is the epidural space the widest?
A
L2
4
Q
Where is the epidural space the narrowest?
A
C5
5
Q
What are the two high points of the vertebral column when the patient is lying supine?
A
L3 and C3
6
Q
What are the two low points of the vertebral column when the patient is lying supine?
A
S2 and T6
7
Q
What is ALWAYS going to be the principle site of action for spinals or epidurals?
A
the nerve root
8
Q
Name the 3 main structures you pass through to get to the epidural space.
A
1) supraspinous ligament
2) interspinous ligament
3) ligamentum flavum
9
Q
What are the 3 primary layers of the spinal meninges before reaching the cord?
A
1) dura mater (outermost–> toughest–> extends from foramen magnum to S2-3)
2) arachnoid mater (middle layer–> delicate, nonvascular–> ends at S2–> almost like spiderweb)
3) pia mater (closely adheres to spinal cord–> delicate, highly vascular)
10
Q
Where is the subarachnoid space and CSF found?
A
between the arachnoid and pia mater
11
Q
What is the easy way to remember the 3 outer layers and location of the subarachnoid space before the spinal cord?
A
DASP Dura Arachnoid Subarachnoid space Pia
12
Q
Where is the epidural space located?
A
it is a potential space bound by the dura mater and the ligamentum flavum
13
Q
Describe the blood supply to the spinal cord and nerve roots.
A
blood supply to the spinal cord and nerve roots is derived from a single anterior spinal artery and paired posterior spinal arteries
14
Q
The principal site of action for neuraxial blockade is the ______.
A
nerve root
15
Q
How much CSF do we have at any time? in the subarachnoid space?
A
100-150ml; 25-35ml
16
Q
How much CSF do we produce per day?
A
500mL
17
Q
How do vasoconstrictors prolong a spinal block?
A
decrease absorption
18
Q
When administering a spinal, where is the concentration the greatest?
A
at the site of injection
19
Q
What is the normal specific gravity of CSF?
A
1.004-1.009
James Bond 1.007 is in the middle
20
Q
Label in relation to CSF: SAME, GREATER, LESS
Isobaric
A
same
21
Q
Label in relation to CSF: SAME, GREATER, LESS
hyperbaric
A
greater
22
Q
Label in relation to CSF: SAME, GREATER, LESS
hypobaric
A
less
23
Q
Is sterile water hypo, hyper, or iso baric?
A
hypobaric
24
Q
Is dextrose 5-8% hypo, hyper, or iso baric?
A
hyperbaric
25
What direction will a hyperbaric spinal given at L2 while the patient was sitting go if the patient is immediately laid supine?
cephalad. Think of the high and low points
26
What determines the duration of spinal anesthesia?
rate of elimination
27
What is the predominant action of a sympathetic blockade d\t local anesthetics?
venodilation
| venodilation--> reduces venous return, SV, CO, and BP
28
What are the two causes for bradycardia following local anesthetic administration?
1) blockade of cardiac accelerator fibers
2) decreased venous return (from venodilation)
* Bainbridge reflex (unopposed vagal stimulation)
29
What is the BEST means for treating hypotension during spinal anesthesia?
physiologic not pharmacologic
| *give fluids if not normovolemic, if normovolemic give ephedrine
30
Why do you not want to give fluids that are rich in glucose, but instead give balanced salt solutions for hypotension?
b\c glucose can act as a diuretic
31
What is the difference between a high spinal and a total spinal?
high spinal is >T4
| total spinal goes all the way
32
What is an advantage of a spinal over epidural?
ability to control the spread of anesthetic by controlling the specific gravity of the solution and the position of the patient
33
Are there any time restraints to receiving neuraxial anesthesia for patients taking NSAIDs or aspirin?
No
34
When can a catheter be removed from a patient on IV heparin therapy?
2-4 hours after the last heparin dose; heparinization can occur one hour after catheter removal
35
What are the special considerations for patients on warfarin therapy?
controversial
- should d\c at least 4 days before surgery
- should check INR (neuraxial block may be given if perioperative INR is <1.5)
36
What is an acceptable INR in order to administer a neuraxial block to a patient on warfarin?
<1.5
37
The catheter should not be removed until INR is _____.
<1.5
38
Do not place or remove a neuraxial catheter if INR is ______.
>1.5
39
What considerations for neuraxial anesthesia should be made for a patient who has received, is receiving, or will be receiving fibrinolytic or thrombolytic drug therapy?
should NOT receive neuraxial for 10 DAYS
40
First dose of LMWH can be given _____ hours after removal of the catheter.
2 hours
41
What are two other names for L4?
1) Tuttier's line
| 2) intercristal line
42
Spinal, epidural, and caudal blocks are all considered ________.
neuraxial anesthesia
43
Describe the distribution of local anesthetic when injected into the subarachnoid space.
spreads to nerves of the cauda equina and laterally to the nerve rootlets and nerve roots--> may also diffuse into the spinal cord
44
Which two structures will you not pass through during a lateral approach to a spinal?
1) supraspinous ligament
| 2) interspinous ligament
45
Infection as a result of spinal anesthesia:
| predisposing factors?? (5)
1) advanced age
2) diabetes mellitus
3) alcoholism
4) cancer
5) AIDS
46
Infection as a result of spinal anesthesia:
| classic symptoms?? (3)
1) high fever (only seen with meningitis, not PDPH)
2) nuchal rigidity
3) severe headache
47
Nausea and vomiting should be viewed as signs of ______ until proven otherwise.
central hypoxia
48
What is the most common complication of spinal anesthesia? second?
backache; headache (PDPH)
49
When does the patient start to feel a PDPH?
within 12-72 hours; the earlier the onset, the more severe
* self limiting
* can last 10 days
50
Name s\s of PDPH (caused by traction on cranial nerves).
1) nausea and loss of appetite
2) photophobia
3) changes in auditory acuity
4) tinnitus
5) depression
6) feel miserable
7) tearful
8) bed-ridden
9) dependent
10) diplopia and cranial nerve palsies
51
What cause a PDPH?
loss of CSF in the subarachnoid space--> medulla and brainstem drop into the foramen magnum, stretching the meninges, vessels, and nerves--> headache
52
Blood patch should be _____ to _____mL.
10-30ml aseptically drawn blood
* injected into epidural space until the patient can feel pressure in back
* after the blood patch, bed rest for 1-2 hours before ambulating
* 1st= 89-95% resolution
53
What are the conservative treatments for PDPH?
1) lie flat
2) hydration
3) caffeine (IV/oral)--> cerebral vasoconstriction
54
In regards to nerve types, what is the order in which they are blocked with local anesthesia?
B fibers--> C fibers and A-delta--> A-gamma--> A-beta--> A-alpha
55
In regards to nerve types, what is the order of most to least sensitive?
"LSU"
Large myelinated
Small myelinated
Unmyelinated
56
Label whether the following is a characteristic of a spinal (S) or epidural (E):
takes less time to perform
S
57
Label whether the following is a characteristic of a spinal (S) or epidural (E):
catheter used for post op pain management
E
58
Label whether the following is a characteristic of a spinal (S) or epidural (E):
pain during surgery is less
S
59
Label whether the following is a characteristic of a spinal (S) or epidural (E):
rapid onset
S
60
Label whether the following is a characteristic of a spinal (S) or epidural (E):
less hypotension
E
61
Label whether the following is a characteristic of a spinal (S) or epidural (E):
sensory and motor block quality is better
S
62
Label whether the following is a characteristic of a spinal (S) or epidural (E):
can prolong block with catheter
E
63
Distance from skin to epidural space:
| Average adult?
4-6cm
64
Distance from skin to epidural space:
| Fat, I mean obese person?
up to 8cm
65
Distance from skin to epidural space:
| thin person?
approximately 3cm
66
Is a lumbar epidural injection associated with a more cranial or caudal spread?
cranial
67
Why may there be a delay in onset to an epidural at L5 or S1?
b\c of the larger size of the nerve roots
68
What is the prevalence of a epidural hematoma?
1:150,000
69
What are the s\s of a epidural hematoma?
sharp back and leg pain--> numbness and weakness, sphyncter dysfunction
70
What is the best test for epidural hematoma?
MRI or CT scan
71
What ensures a good outcome for a patient with a epidural hematoma?
surgical decompression within 8-12 hours
72
Name some complications of epidural blockade:
- penetrate a blood vessel
- epidural hematoma
- dural puncture
- back ache
- neural trauma
- air embolism (children)
- subdural catheterization
- intravascular catheterization (small alloquots)
- infection
- headache
- hypotension
- resp depression/resp failure
- bradycardia
- total spinal secondary to subarachnoid injection (intubate and sedate)
- Horner's syndrome
- trigeminal nerve palsy
73
Why do you perform a test dose after satisfactory placement of a epidural catheter?
to detect both subarachnoid and intravascular injection
74
What is the most common regional anesthetic in children?
caudal block
75
Where do you insert the needle when doing a caudal block?
through the sacrococcygeal membrane
* the injection should feel like an injection into the epidural space
* should be NO local pain on injection
76
When doing a caudal block should you be able to aspirate CSF, air, or blood?
No
77
What is the "whoosh" test?
for caudal blocks--> whoosh test with air while listening with stethoscope over midline lumbar spine
78
When performing a caudal block, the patient reports a feeling of fullness or paresthesia from the sacrum to the soles of the feet. What should you do?
nothing, this is normal during injection and will cease upon completion
79
A volume of _____ml is required to get a sensory level block at T10 to T12.
25-35mL
80
Is caudal or epidural anesthesia associated with higher plasma levels?
caudal
81
Is distribution time longer for epidural or for caudals?
caudal; d\t nerve size
82
What is the most frequent problem with caudal blocks?
ineffective blockade
83
What is the most common post-op complaint after a caudal block?
pain at insertion site
84
What are the two greatest advantages of US guided regional anesthesia?
1) ability to see where the tip of needle is in relation to anatomical structures
2) see the spread of local anesthesia
85
What are high frequency sound waves generated in specific frequency ranges and sent through tissues?
ultrasound waves
86
_____ frequencies penetrate deeper than _____ frequencies.
lower; higher
87
What is best to visualize shallow structures less than 4cm from the skin?
high frequency (10-13mHz)
88
What is best for visualizing deeper structures?
low frequency (2-5mHz)
89
As sound passes through tissue it is ______, _______, or allowed to _________, depending on the echodensity of the tissue.
absorbed, reflected, pass through
90
Substances that absorb sound well are termed ______.
anechoic (echolucent)
91
Anechoic substances like blood and CSF (high water content) appear _____ on a US.
dark
92
Substances low in water content or high in materials that are poor sound conductors are called _______. Give examples.
hyperechoic (they bounce the sound back)
| -air and bone
93
How do hyperechoic substances appear on the US?
very bright
94
The middle "shades of gray" on a US are due to substances that fall in the middle of anechoic and hyperechoic. These are called _____.
hypoechoic (vessels, etc)
95
If you are doing a caudal block for a child, what is the initial dose?
0.5-1.0mg/kg of 0.125% to 0.25% bupivacaine
96
Where in the plexus is the phrenic nerve located?
C3-C5, but C4 is 70% contribution
97
What is the cervical plexus?
C1-C5
98
What is the brachial plexus?
C5-C8, T1
99
Name the dermatome and nerve involved.
| pain in small finger
ulnar nerve, C8
100
What two nerves innervate the thumb?
radial and median
101
What is the only nerve that gives extension in the hand?
radial nerve
102
Name the nerve:
| supination of forearm
radial
103
Name the nerve:
| pronation of forearm
median
104
What nerve provides flexion at the wrist?
median and ulnar
105
________ nerve provides extension at the elbow, while ________ nerve provides flexion at the elbow.
radial; musculocutaneous
106
What surgery is a good indication for use of a cervical block?
CEA
107
Ipsilateral means _______.
same side
108
Contralateral means ______.
opposite side
109
A cervical plexus block is performed for C____ to C_____ by injecting ____mL of local anesthetic at each level.
C1-C4; 4mL
110
What are 4 complications that can result from a cervical plexus block?
1) block phrenic nerve (hiccups)
2) Horner's syndrome (ipsilateral ptosis, miosis, facial and arm flushing, anhydrosis, and nasal congestion)
3) hoarseness (RLN block)
4) accidental subarachnoid or epidural injection
111
Which plexus block provides adequate analgesia for shoulder and proximal humerus?
interscalene
| Intense C5-C7, Least C8-T1
112
______ is the level of the cricoid cartilage.
C6
113
What nerve may not be blocked with a interscalene block?
ulnar nerve
114
Puncture of the _______ artery is a complication of an interscalene block.
vertebral artery
115
What block: Where is the brachial plexus MOST compact (3 trunks)?
supraclavicular block
116
What is the most homogenous block of the brachial plexus that even includes the ulnar nerve?
supraclavicular
117
What is the biggest risk associated with supraclavicular blocks?
pneumothorax
118
What is "X" marks the spot for a supraclavicular block?
1) most inferior part of the interscalene groove
| 2) 2 cm's from midpoint of the clavicle
119
What is the major concern when performing a infraclavicular block?
1) pneumothorax
| 2) hemothorax
120
Which plexus block ensures blockade of the musculocutaneous nerve?
infraclavicular
121
Brachial Plexus Anatomy at the Axilla:
| What nerves are in the bundle at this level?
1) musculocutaneous (but lies outside the sheath--> requires a separate block to cover)
2) median
3) radial
4) ulnar
122
Can you do both a ulnar and radial block at the hand?
not at the same time--> compromise circulation
123
EPI should not be added to blocks __________.
below the elbow
124
What is the BEST block for knee surgery?
femoral and sciatic
125
What is the largest nerve trunk in the body?
sciatic (lumbosacral trunk)
126
What nerves compose the lumbosacral trunk?
L4-5, S1-3
127
The sciatic provides sensory to where?
sensory fibers to the posterior hip capsule as well as the knee; ALL sensory distal to the knee except the anteromedial aspect which is covered by the saphenous; motor to the hamstrings and to all the lower extremity muscles distal to the knee
128
What are the complications associated with a retrobulbar block?
1) retrobulbar injection
2) retrobulbar hemorrhage: bleeding in eye, temp loss of vision, lens occluded by blood, IOP may decrease
3) Intra-arterial injection (MOST COMMON; 1-3%)
4) injection into optic nerve sheath
5) oculocardiac refex
129
How long must you leave the tourniquet up for following a Bier block?
20 min or you can get LA toxicity
130
The most common causative organism in epidural abscesses is: ________.
staphylococcus aureus
131
When doing a CSE, how far should the spinal needle extend beyond the tip of the epidural needle?
7-10mm
132
How much clonidine should you add to your spinal anesthetic?
15-45mcg
133
What is the recommended dose (mg) for epinephrine when added to tetracaine?
0.2 to 0.3
134
What level of spinal anesthesia will be necessary to eliminate thigh tourniquet discomfort?
T12
135
What is the easiest, most frequently used, and lowest complication risk of the brachial plexus blocks?
axillary
136
The axillary approach to the brachial plexus block is best suited for procedures where?
elbow, hand, forearm
137
How much pressure should you apply on the proximal tourniquet when administering an IV regional anesthetic in the upper extremity?
SBP + 100
138
What nerve is immediately lateral to the achilles tendon in the patients ankle?
sural
