Neuraxial blocks Flashcards
1
Q
How many cervical vertebrae are there?
A
7
2
Q
How many thoracic vertebrae are there?
A
12
3
Q
How many Lumbar vertebrae are there?
A
5
4
Q
How many sacral vertebrae are there?
A
5~fused
5
Q
How many coccygeal vertebrae are there?
A
4~fused
6
Q
What is the vertebral foramen?
A
Space that contains the spinal cord, nerve roots, and epidural space
7
Q
What is vertebrae C1 also called?
A
The atlas
8
Q
What is vertebrae C2 also called?
A
The axis (this vertebrae has the dens!)
9
Q
What is another name for the facet joint?
A
Zygapophyseal joint
10
Q
Where is the vertebra prominens?
A
C7
11
Q
Where is the SPINE of the scapula?
A
T3
12
Q
Where is the Inferior angle of the scapula?
A
T7
13
Q
At what level is the rib margin?
A
L1
14
Q
At what level is the iliac crest?
A
L4
15
Q
At what level is the posterior iliac spine?
A
S2
16
Q
What is another name for the intercristal line?
A
Tuffier’s line ~ correlates with L4 vertebra
17
Q
Where is the sacral hiatus?
A
S5
Covered by the sacrococcygeal ligament
Entry point to the epidural space in pediatrics
18
Q
What are the sacral Cornu?
A
Bony nodukes that flank the sacral hiatus
19
Q
Where does the spinal cord end in an adult (aka conus medullaris)?
A
Adult: L1-L2
20
Q
Where does the spinal cord end in the infant? (Aka conus medullaris)
A
L3
21
Q
What is the cauda Equina?
A
Bundle of nerve fibers extending from conus medullaris to Duran sac
22
Q
Where does the Dural sac terminate in the adult?
A
S2
23
Q
Where does the dural sac terminate in the infant?
A
S3
24
Q
What is the film terminale?
A
Continuation of pia mater that extends from the conus medullaris to coccyx
Anchors spinal cord to coccyx
25
What is the order of the five ligaments in the spinal column? From outside in…
Supraspinous
Interspinous
Ligamentum flavum
Posterior longitudinal ligament
Anterior longitudinal ligament
26
What ligaments does the needle pass in the midline approach?
Supraspinous
Interspinous
Ligamentum flavum
27
What ligaments does the needle pass in the paramedical approach?
Ligamentum flavum
28
What are the 3 meninges layers of the spinal cord? From outside in?
DAP
Dura
Arachnoid
Pia
29
What is the cranial border, caudal border, anterior border and posterior border of the epidural space?
Cranial (top) foramen magnum
Caudal (bottom): sacrococcygeal ligament
Anterior: posterior longitudinal ligament
Posterior: ligamentum flavum
30
How does the epidural space affect lipophilic drugs?
Acts as a sink reducing bioavailability
(Bupi > Lido > morphine)
31
What is another name for the epidural veins?
Bataan’s plexus
They pass the anterior and lateral regions of the epidural space
**pregnancy and obesity increase intraabdominal pressure and cause engorgement of these vessels
32
What is the plica mediana dorsalis?
Hypothetically…this is a band of tissue that courses b/t the ligamentum flavum and dura mater.
** been considered the culprit for difficult epidural catheter insertion
33
What is a tough fibrous shield that protects the spinal cord?
Dura mater
34
What is a potential space b/t the dura mater and the arachnoid mater?
Subdural space
35
What is a thin layer of connective tissue that neighbors the dura mater?
Arachnoid mater
36
Which space is deep to the arachnoid mater and contains CSF, nerve roots, and the spinal cord?
Subarachnoid space
37
What is the external covering of the spinal cord?
Pia mater.
38
What does C6 innervate?
1st digit (thumb)
39
What does C7 innervate?
2nd and 3rd middle digits
40
What does C8 innervate?
4th and 5th digits
41
What does T4 innervate?
Nipple line
42
What does T6 innervate?
Xiphoid process
43
What does T10 innervate?
Umbilicus
44
What does T12 innervate?
Pubic symphysis
45
What does L4 innervate?
Anterior knee
46
What sensory level is necessary for an upper abd surgery, c-section, or cystectomy?
T4
47
What sensory level is necessary for a lower abdominal surgery/appendectomy ?
T6-T7 (xiphoid process)
48
What sensory level is necessary for a total hip arthroplasty, Vaginal delivery, or TURP
T10
49
What sensory level is necessary for a lower extremity surgery?
L1-L3
50
What sensory level is necessary for a foot surgery?
L2-L3
51
What sensory level is necessary for a hemorrhoidectomy?
S2-S5
52
What are some controllable factors for spinal anesthesia?
Baricity
Patient position
Dose
And Site of injection
53
What are some controllable factors for epidural anesthesia?
Local anesthetic volume (most imp.)
Level of injection
Local anesthetic dose
54
How does the level of injection affect the spread in epidural anesthesia?
Lumbar: cephalon
Midthoracic: both cephalon and caudad
Cervical: caudad
55
In spinal anesthesia, what is the sensory blockade, what is the autonomic blockage and what is the motor blockade?
Sensory: usually 2 dermatomes ABOVE motor
Autonomic: usually 2-6 dermatomes ABOVE sensory
Motor: usually 2 dermatomes BELOW sensory
56
In epidural anesthesia, what is the sensory blockade, what is the ANS blockade, and what is the motor blockade?
Sensory and ANS are 2-4 dermatomes ABOVE motor
57
What is the first sensory modality blocker? What is the second? What is the last?
1st: sense of temperature
2nd: pain
3rd: sense of light touch or pressure
58
Where is the primary site of action of a spinal anesthetic?
In the subarachnoid space ~ myelinated preganglionic fibers of the spinal nerve roots
59
For a spinal anesthetic, what is the dose of bupivaciane at the T10 level and what is the dose at the T4 level?
T10: 10-15mg
T4: 12-20 mg
60
For a spinal anesthetic, what is the dose of Levobupivacaine at the T10 level and what is the dose at the T4 level?
T10: 10-15 mg
T4: 12-20 mg
61
For a spinal anesthetic, what is the dose of ropivacaine at the T10 level and what is the dose at the T4 level?
T10: 12-18mg
T4: 18-25 mg
62
For a spinal anesthetic, what is the dose of Chloroprocaine 3% at the T10 level and what is the dose at the T4 level?
T10: 30-40 mg
T4: 40-60 mg
63
For a spinal anesthetic, what is the dose of tetracaine at the T10 level and what is the dose at the T4 level?
T10: 6-10 mg
T4: 12-16 mg
64
What is the initial dose per segment to be blocked in an epidural?
1-2 mL per segment
65
What is a “top up” dose?
50-75%
66
What is the difference b/t specific gravity and baricity?
Both are the density of a substance relative to a substance
Specific gravity = water
Baricity = CSF
67
What is an isobaric solution?
Baricity is similar to CSF
68
What is a hyperbaric solution?
Baricity is greater ~ higher density > 1
Dextrose is added to increase Baricity
69
What is a hypobaric solution?
Baricity is lower ~ lesser density < 1
Water is added to reduce Baricity
70
Which is the only solution that is hyperbaric in water?
Procaine 10% in water (there are a lot of molecules in procaine)
71
What are the highest points of lordosis in the supine position?
L3
C5
72
What are the high points of kyphosis in the supine position?
T5-T7 and S2
73
What can occur if you have unloading of the ventricular mechanoreceptors?
Activation of the Bezold-Jarisch reflex (this can lead to asystole with spinal anesthesia
74
How does neuraxial anesthesia affect the resp system?
Accessory muscle function is reduced. ~this can reduce pulmonary reserve.
75
What is usually the culprit if a patient becomes apneic with neuraxial anesthesia?
Brainstem hypoperfusion.
76
How does neuraxial anesthesia affect the CNS?
Reduces sensory input to the reticular activating system ~ causes drowsiness
77
How does neuraxial anesthesia affect the Neuro endocrine system?
Inhibits afferent traffic and diminishes the stress response
78
How does neuraxial anesthesia affect the GI system?
Relaxes sphincters and increases peristalsis
79
What do opioids NOT cause in spinal or epidural anesthesia?
Sympathectomy
Skeletal muscle weakness
Changes in proprioception
80
What are some traits about hydrophilic drugs administered in the intrathecal/epidural administration?
Spread: extensive (more rostral spread)
Wider band of analgesia
Site of action: rexed laminae II and 3
Onset: 30 mins
Duration: 6-24 hours
**resp depression (early < 6 hrs; late > 6 hrs)
N&V: increased
Pruritus: increased
81
What are some traits about lipophilic drugs that are administered in the epidural and spinal space?
Spread: stays in CSF for shorter period of time (less rostral spread)
Narrow band of analgesia
Site of action: rexed laminae 2 and 3/systemic
Onset: 5-10 mins
Duration: 2-4 hours
Resp depression: early
N&V: less
Pruritus: less
82
What is the intrathecal dose and epidural dose of sufentanil?
Intrathecal: 5-10 mcg
Epidural: 25-50 mcg
83
What is the intrathecal dose and epidural dose of fentanyl?
Intrathecal: 10-20 mcg
Epidural: 50-100 mcg
84
What is the intrathecal dose and epidural dose of hydromorphone?
Intrathecal: ~
Epidural: 0.5-1 mg
85
What is the intrathecal dose and epidural dose of meperidine?
Intrathecal: 10 mg
Epidural: 25-50 mg
86
What is the intrathecal dose and epidural dose of morphine?
Intrathecal: 0.25 - 0.30 mg
Epidural: 2-5 mg
87
What is the most common side effect of neuraxial opioid administration?
Pruritus
Then resp depression > urinary retention > N&V
88
Why do opioids cause Pruritus?
Stimulation of opioid receptors in the Trigeminal nucleus
**must be treated with an opioid antagonist, such as naloxone
89
How does neuraxial opioids cause urinary retention?
Inhibition of sacral parasympathetic tone ~ bladder detrusor muscle relaxation and urinary sphincter muscle contraction
90
How do opioids cause N&V?
Activation of opioid receptors in the area posted a of the medulla and vestibular apparatus
91
What can epidural morphine reactivate?
Herpes
92
Which local anesthetic reduces the efficacy of epidural opioids?
2-Chloroprocaine
93
What is ALWAYS an absolute contraindication to neuraxial anesthesia?
Patient refusal
94
At what platelet count would a neuraxial technique be contraindicated?
<100,000
95
Which anesthetic technique is preferred for a patient with MS?
Epidural is relatively safe, but intrathecal may exacerbate symptoms
96
What 3 vascular lesions are generally considered contraindications for neuraxial anesthesia?
Severe Aprtic stenosis
Severe Mitral stenosis
Hypertrophic cardiomyopathy
97
What is an example of a cutting needle?
Quincke
(Requires less force)
98
What are two examples of a pencil point needle?
Sprotte
Whitacre
99
What are the pros of a cutting needle? What are the cons?
Pros: requires less force
Cons: higher risk of PDPH, less tactile feel, needle more easily deflected, more likely to injure nerve roots
100
What are the pros of a pencil point? What are the cons?
Pros: lower risk of PDPH, more tactile feel, needle less likely to deflect, less likely to injure nerve roots
Cons: requires more force
101
How are epidural needles differed?
By the amount of curvature at the needle tip
Needle angle increases in alphabetical order
Crawford ~ 0
Hustead ~ 15
Tuohy ~ 30 degrees
102
How deep is the epidural space in most adults?
3-5 cm from the skin.
103
What are absolute contraindications to caudal anesthesia?
Spina bifida
Meningomyelocele of the sacrum
Meningitis
104
What are the two landmarks for a caudal anesthetic?
Posterior superior iliac spines and the sacral hiatus
105
What is the dose for a caudal anesthetic that goes to the sacral height?
Peds: 0.5 mL/kg
Adult: 12-15 mL
106
What is the dose for a caudal anesthetic that goes from the sacral to low thoracic (~T10)?
Peds: 1 mL/kg
Adults: 20-30 mL
107
What is the dose for a caudal anesthetic that goes from sacral to mid thoracic?
Peds: 1.25 mL/kg (this should be avoided though)
108
What are some common pediatric procedures where a causal is useful?
Circumcision
Hypospadias repair
Anal surgery
Inguinal hernia
Low thoracic surgery
109
What are the presenting symptoms of an epidural hematoma?
Lower extremity weakness
Numbness
Low back pain
Bowel and bladder dysfunction
110
If a patient has an epidural hematoma, how soon should surgical decompression be initiated?
Within 8 hours!!
111
How long should you hold COX-1 inhibitors prior to neuraxial block?
Examples: asa, NSAID
Management: none of labs look ok.
112
How long should you hold a glycoprotein IIb/IIIw antagonist?
Example: tirofiban, eptifibatide, abciximab
Management:
Before block: hold tirofiban and eptifibatide 4-8 hrs; hold abciximab 24-48 hours
(Contraindicated within 4 weeks of surgery)
113
How long should you hold a thienopyridine derivative?
Examples: clopidogrel, prasugrel, ticlopidine
Before block:
5-7 days with Clopidogrel
7-10 days with prasugrel
10 day hold ticlopidine
114
How long should you hold heparin for a neuraxial block!?
Before block:
Low dose (5,000) ~ hold 4-6 hours
Higher dose (< 20,000) ~ hold 12 hr
Therapeutic dose (>20,000) ~ hold 24
May restart heparin after 1 hour
115
How long should you hold heparin after removal of neuraxial catheter?
SubQ ~ hold 4-6 hours
IV ~ hold 4-6 hours after IV infusion discontinued.
(After catheter removal ~ restart in 1 hour)
116
How long should you hold low molecular weight heparin (lovenox) for neuraxial anesthesia?
Before block placement:
Prophylactic: hold for 12 hours
Therapeutic dose: hold for 24 hours
(After block placed, delay first dose by 12 hours after block)
117
How long should you wait for catheter removal with a patient on low molecular heparin (lovenox)
Catheter removal:
Remove before lovenox if possible or delay first dose 4 hours after removal
Otherwise remove 12 hours after last dose and HOLD next dose for at least 4 hours
118
How long should you hold for a patient taking warfarin requesting neuraxial anesthesia?
Before block
Hold: 5 days
Catheter removal: wait until INR < 1.5
119
How long should you hold for a patient taking oral anti-factor 10a agents requesting neuraxial anesthesia?
Before block:
72 hrs (3 days)
Catheter removal: must wait 6 hrs prior to first postoperative dose
120
What is an ABSOLUTE contraindication to neuraxial anesthesia?
Thrombolytic agents
121
What causes a post-dural puncture headache?
As CSF pressure is lost, cerebral vessels dilate, the brain stem sags into the foramen magnum and stretches the meninges and pulls on the tentorium
122
What are some patient factors that increase the risk for PDPH?
Younger
Female
Pregnancy
123
What are some practitioner factors?
Cutting tip needle
Larger diameter needle
Using air for LOR
Needle PERPENDICULAR instead of parallel
124
What is the treatment for PDPH?
Bed rest
NSAIDs
Caffeine
Epidural blood patch (the DEFINITE treatment)
Sphenopalatine ganglion block
125
What is the most common side effects following epidrual blood patch?
Backache and radicular pain
126
What are the two routes by which an infectious organism can reach the CSF?
Failure of aseptic technique
Bacteria in the patient’s blood at the time of SAB
127
What is the most common bacteria for post-spinal meningitis?
Streptococcus
128
What is the MOST effective way to prevent post-spinal bacterial meningitis?
Alcohol and chlorhexidine
129
What is cauda equina syndrome?
Neurotoxicity as result to high concentrations of local anesthetic
130
What factors increase the risk of cauda equina syndrome?
5% lido
Spinal microcatheters
131
What are the signs and symptoms of cauda equina syndrome?
Bladder and bowel dysfunction
Weakness
Sensory deficits
Paralysis
Treatment: supportive
132
What is transient a Neurological Symptom?
Usually develops because of patient positioning, stretching of the sciatic nerve, myofascial strain, and/or muscle spasm
133
What factors increase the risk of transient neurological symptoms?
Lidocaine, lithotomy, ambulatory surgery, and knee arthroscopy
134
What are some signs and symptoms of transient neurological symptoms?
Severe back and butt pain that radiates to both legs
Develops within 6-36 hours and lasts 1-7 days
135
What is the tx for transient neurological symptoms?
NSAIDs
Opioids
Trigger point injections
136
What happens if a neuraxial catheter breaks off?
Leave the fragments in the patient, alert the patient, and watch for complications.
137
What do you do if there is blood in the NEEDLE?!
Needle was inserted too laterally
Redirect midline
138
What do you do if there is blood in the epidural catheter?
Pull the catheter back a little, flush, and repeat procedure till you are unable to aspirate blood and/or not enough catheter remains in the space
139
What do you do for a failed spinal (no anesthesia)
If a spinal does not set up in 15-20 mins, it is reasonable to repeat the injection
140
What do you do with a patchy spinal?
Do NOT repeat spinal ~ transition to another technique
141
What do you with a unilateral block?
Position the patient with the poorly blocked side down and administer several mL of anesthetic ~ if not, consider another technique
