spinal and epidural neuraxial pharmacology exam one Flashcards
(127 cards)
1
Q
example of esters
A
benzocaine
cocaine
chloroprocaine
procaine
tetracaine
2
Q
examples of amides
A
bupivacaine
dibucaine
lidocaine
mepivacine
ropivacaine
3
Q
onset of action is determined by
A
pka
4
Q
potency is determined by
A
lipid solubility
5
Q
duration of action is determined by
A
protein binding (a1-acid glycoprotein)
6
Q
LA inhibition of peripheral nerves occurs in what order
A
- B fibers
- c fibers
- small diameter A fibers
- large diameter A fibers
7
Q
Factors influencing vascular uptake and plasma concentration of LA
A
- site of injection
- tissue blood flow
- physiochemical properties
- metabolism
- additon of vasoconstrictor
8
Q
put in order the injection sites for local anesthestics from highest to lowest blood concentration: (i took cocaine, pastout everthign became super slow)
A
intravenous
tracheal
intercostal
caudal
paracervical
epidural
brachial
sciatic
subcutaneous
9
Q
refers to the density of a local anesthetic solution compared to the csf
A
Baracity
10
Q
what solution has density equal to csf, barcity = 1 and tends to stay in place where it is injected
A
isobaric
11
Q
what solution has a density greater than csf (baracity >1)
sinks within the csf, moving downward from site
A
Hyperbaric
12
Q
what solution has a density less than csf, baracity <1
rises within csf, moving upward from site
A
hypobaric
13
Q
examples of hyperbaric local anesthetics
A
Bupivacaine 0.75% in 8.25% dextrose
lidocaine 5% in 7.5% dextrose
Tetracaine 0.5% in 5% dextrose
procaine 10% in water
14
Q
why is procaine 10% in water hyperbaric
A
many molecules present in the solution
15
Q
examples of isobaric solution
A
bupivicaine 0.5% in saline
bupivicaine 0.75% in saline
lidocaine 2% in saline
tetracaine 0.5% in saline
16
Q
examples of hypobaric solution
A
Bupivicaine 0.3% in water
Lidocaine 0.5% in water
Tetracaine 0.2% in water
17
Q
what are the highest points (apexes) of the spinal column when supine
A
C3 AND L3
18
Q
what are the lowest points (troughs) of the spinal column when supine
A
T6 and S2 are the lowest levels (troughs)
19
Q
when you have a hyperbaric solution whats the furthest it can go and why is this significant
A
T6
close to T4, expect hypotention and bradycardia
20
Q
SPINAL
Bupivacaine 0.5-0.75%
dose T4
dose T10
onset
duration for plaine/ with epi
A
T10=10-15mg
T4= 12-20mg
onset: 4-8 mins
duration: 130-220
duration with epi: +20-50%
21
Q
SPINAL
Levobupivacaine 0.5%
dose T4
dose T10
onset
duration for plaine/ with epi
A
T10: 10-15mg
T4: 12-20mg
onset: 4-8mins
duration: 140-230
22
Q
SPINAL
Ropivacaine 0.5-1%
dose T4
dose T10
onset
duration for plaine/ with epi
A
T10: 12-18mg
T4: 18-25mg
onset: 3-8 mins
duration: 80-210 mins
23
Q
SPINAL
2-chloroprocaine 3%
dose T4
dose T10
onset
duration for plaine/ with epi
A
T10: 30-40mg
T4: 40-60mg
onset: 2-4 mins
duration: 40-90 mins
24
Q
SPINAL
Tetracaine 0.5-1%
dose T4
dose T10
onset
duration for plaine/ with epi
A
T10: 6-10mg
T4: 12-16mg
onset: 3-5 mg
duration: 90-120
duration with epi: +20 - 50%
25
the spread for epidural is what way
both cephalad and caudad from catheter insertion site
26
when incremental dosing with 5ml during epidurals avoid
accidental high spinal
hypotension from rapid autonomic blockade(cardiac arrest)
local anesthetic toicity
27
epidural onset
10-25 mins
28
2-chloroprocaine facts
comes in 2% and 3%
3% surgical anesthesia
popular in ob
short lived, redose 45 mins
ester
rapid
29
how to speed up the onset of an epidural
Alkalinzation
30
how does Alkalinzation increase onset
adds NaHCO3
increases ph of LA
increase the concentratin of nonionized free base
increase the rate of diffusion of the drug
increase the speed of onset of the block
31
# EPIDURAL
For epidural what is crucial for determining how high the anesthetic block reaches
volume
32
Epidural initial dose
1-2ml per segment of the spine
33
amount of top dose and timing
50-75% of initial dose
administer before the block decreases more than 2 dermatomes
34
Epidural space variation
thoracic vs lumbar
thoracic region epidural space is smaller than lumbar greater spread in thoracic
35
epidural concentration determines
determines block density (how strong the block is)
36
# EPIDURAL
2-chloroprocaine
concentration
onset
duration
concentration: 3%
onset: 5-15 mins
duration: 30-90 mins
37
# epidural
lidocaine
cconcentration
onset
duration
concentration: 2%
onset: 10-20mins
duration: 60-120 mins
38
# Epidural
Ropivacaine
concentration
onset
duration
concentration: 0.1 -0.75%
onset: 15-20 min
duration 140-220 min
39
# epidural
Bupivacaine
concentration
onset
duration
concentration 0.0625-0.5%
onset: 15-20 min
duration: 160-220mins
40
# epidural
Levobupivacaine
concentration
onset
duration
concentration 0.0625-0.5%
onset: 15-20 min
duration 150-225 mins
41
Benefits of neuraxial pharmacologic Adjuncts
provides postop analgesia, extends duration and improves the density of the block
42
what does opiods as adjuncts for neuraxial do
sufentanil, fentanyl and morphine
no extention of duration
analgesia/density: yes
43
what does Alpha 2 agonists do as adjuncts to neuraxial
improves density, duration and analgesia
44
what do vasopressors as adjuncts do to neuraxial
extends duration only: no effect on density or analgesia
epinephrine: good iv marker epidurals: initial bolusing
phenelphrine
45
what is being investigated as adjuncts
neostigmine, magnesium, ketamine, versed
46
what does neuraxial opioids target
substantia gelatinosa of the dorsal horn (lamina 2)
47
neurotransmission is reduced by
decreased cAMP
decreased Ca++ conductancce and increased K+ conductance
48
example of hydrophillic opioids
morphine
hydropmorphone
meperidine
49
example of lipophillic opiods
fentanyl
sufentanil
50
**Hydrophillic opioids **
duration in csf
spread
onset
duration
systemic absorption
respiratory depression
duration in csf: stays longer
spread: wide, affects large area for pain relief
onset: takes long to work 30-60 misn
duration: lasts longer: 6-24 hrs
systempic absorption: stays longer in csf, less
respiratory depression: occurs late
51
**Lipophillic**
duration in csf
spread
onset
duration
systemic absorption
respiratory depression
duration in csf: short
spread: limited, less rostral spread
onset: fast 5-10 mins
duration: short 2-4 hrs
systemic absorption: absorbed more by body
respiratory depression: early after admin
52
intrathecal and epidural opiod dosing for sufentanil
intrathecal dose: 5-10 mcg
epidural dose: 25-50 mcg
epidural infusion dose 10-20 mcg/hr
53
intrathecal and epidural opiod dosing for fentanyl
intrathecal dose: 10-20 mcg
epidural dose: 50-100 mcg
epidural infusion dose 25-100 mcg/hr
54
intrathecal and epidural opiod dosing for Hydromorphone
intrathecal dose:n/a
epidural dose: 0.5-1mg
epidural infusion dose : 0.1-0.2mg/hr
55
intrathecal and epidural opiod dosing for Meperidine
intrathecal dose: 10mg
epidural dose: 25-50mg
epidural infusion dose : 10-60 mg/hr
56
intrathecal and epidural opiod dosing for morphine
intrathecal dose: 0.25-0.30 mg
epidural dose: 2-5mg
epidural infusion dose: 0.1-1 mg/hr
57
Treatment for pruitis that occur from neuraxial adjuncts
Benadry 25-50 mg IV
Naloxone 0.1 mg iv: best
Buprenex: mixed agonist/antagonist
58
neuraxial adjuncts pruitius prophylaxis
ondansetron 4 mg IV
Nubaine 2.5-5.0 mg iv
minimize dose of morpine <300
59
Neuraxial adjuncts respiratory depression
* delayed or immediate first 24 hrs
* higher incidence with morphine
* hydrophilic nature causes cephalad spread
60
intrathecal morphine requires apnea monitoring using
capnograhy
pulse oximetry
alarms
61
Treatment for respiratory depression occuring from neuraxial adjuncts
naloxone 0.1-0.2 mg
62
Nausea/Urinary retention that occurs with neuraxial adjuncts
dose dependence: morphine <300 mcg: dose of <100mcg almost absent
used in combination: Fentanyl/Sufentanil + Morphine has a very high incidence
63
Treatment for nausea/urinary retention that occurs with neuraxial adjuncts
ondansetron
naloxone 0.1mg
phenergan 12.5-25mg im
64
What vasoconstrictors do when added to local anesthetics
prolongs action of the LA by reducing blood flow
65
Vascoconstrictor doses for neuraxial adjuncts
epinephrine 0.2-0.3. mg: epi wash
phenylephrine=2-5mg
66
what happens when vasoconstrictors are added to tetracaine, bupivacaine or lidocaine
tetracaine: pround increase
bupivacaine or lidocaine: variable increase
67
patients on anticoags should avoid neuraxial anesthesia why
epidural hematoma
68
symptoms of epidural hematoma
lower extremity weakness, numbness, low back pain
bowel and bladder dysfunction
69
treatment for epidural hematoma
surgical decompression within 8 hours
70
when do you hold asprin for high risk and intermediate risk procedures
4-6 days
71
when do you hold aspirin for low risk procedures
do not need to hold aspirin
72
what inhibits cycloxygenase which prevents the formation of the potent platelet aggregation of thromboxane A2
COX-1 Inhibitors
73
considerations for Nsaids prior to surgery, for high, intermediate, low risk procedures and central neuraxial blocks
High: hold 5 half lives
Intermediate: hold for cervical ESI and stellate ganglion block
low: do not need to routinely hold
central: no additional precautions
74
low cardiac risk <1% surgeries
endoscopic procedures
cataract surgery
superficial surgeries
breast surgeries
ambulatory surgery
75
intermediate cardiac risk surgery
carotid endarerectomy
head and neck surgeries
intrathoracic or intra abdominal
orthopedic surgeries
prostate surgery
76
High cardiac risk >5%
emergency surgery
open aortic surgeries
peripheral vascualar surgeries
long surgeries with significant volume shifts and blood loss
77
Glycoprotein IIB/IIIA Antagonists inhibits platelets aggregation via
surface receptors
78
examples of Glycoprotein IIB/IIIA Antagonsits
Triofiban, Eptifibatide, Abciximab
79
Glycoprotein IIB/IIIA considerations
Triofiban, Eptifibatide, Abciximab
avoid until platelet function has recovered
Triofiban and Epifibatide: Hold for 4-8 hours
Abciximab: Hold 24-48 hours
80
Thienopyridine derivaties inhibits platelet aggregation by
blocking ADP transferase
81
Examples of Thienopyridine derivatives
clopidogrel(plavix)
prasugrel (Effient)
Ticlopidine (Ticlid)
82
considerations for
clopidogrel(plavix)
prasugrel (Effient)
Ticlopidine (Ticlid)
clopidogrel: 5-7 days
prasugrel: 7-10 days
Ticlopidine: 10 days
83
unfractionated heparin potentiates antithrombin and inhibits
factors 2,9,10,11,12
84
unfractionated heparin regiona anesthesia consideration
low dose <5000: hold 4-6 hours
Higher dose < or = 20000: hold 12 hours
therapeutic dose: >/= 20000, or pregnant women : hold 24 hours
UFH > 4 days: have platelet count before central neuraxial block
85
LMW Heparin inhibits
factor 10a
lovenox
dalteparin
tinzaprin
86
LMWH consideration
ensure normal coags
no other blood thinners used
check plt count if on LMWH >4 days
87
LMWH consideration before block/catheter placement
delay at least 12 hrs after prophylactic dose
delay 24 hours after therapeutic dose
check 10a activity in elderly or renal insuffiency
88
vit k antagonists impairs what factors and what are the considerations
2,7,9,10
* hold 5 days verify INR
* ensure INR <1.5
89
Thrombolytic Agents activates what
and examples
plasminogen
TPA, Streptokinase, Altepase, Urokinase
90
Thrombolytic Agent consideration
absolute contraindication to neuraxial anesthesia
91
Direct oral anticoagulants inhibits what? and examples
10a
apixaban, betrixaban, edoxaban, rivaroxaban, dabigatran
92
Direction oral anticoagulants regional anesthesia consideration
discontinue at least 72 hours before block
consider checking drug level or anti-factor 10a activity if <72 hours
93
symptoms of postdural puncture headache
headache that is worse sitting or standing than lying donw
headache from forehead to the back of the head
nausea, sensistivity to light, double vision, ringing in ears
94
factors that increase risk of PDPH
younger
female pregnant
using needle with cutting tip
large diameter needle
air from LOR with epidural
positioning needle perpendicular to the spines long axis
95
PDPH treatment
bedrest
nsaids
caffiene
epidural blood patch
sphenopalatine ganglion block
96
when is a blood patch not recommended
within 24 hours of dural puncture
48 hours is the standard
97
how much blood is injected into the epidural space
10-20 ml of patients own blood
98
what is the sphenopalatine ganglion block procedure
soak a cotton swab with LA (1-2% lidocaine or 0.5% bupivacaine)
with the patients head tilted back insert the swab, leave for 5 to 10 mins
99
what increases the risk of nerve injury during neuraxial procedures
paresthesia
CSE techniques
noncooperative patients
100
what decreases risk of nerve injury during neuraxial procedures
redirect needle if paresthesia is elicited
epidural catheter= lower risk
identify midline
document
101
what are signs of failed spinal
no anesthesia effect in 15-20 mins
patch block: avoid repeating can cause neurotoxicity
unilateral block: adjust block
102
post spinal bacterial meningitis cause and txt
streptococcus viridian
follow aseptic technique
103
cauda equina syndrome:
nerve affected
cause
factors that increase risk
nerve: cauda L1-S4 nerve
cause: neurotoxicity
factors: high concentration, microcatheter, whiticare 25/26
104
cauda equina syndrome signs and symptoms
neuro complications that are permanent
bowel and bladder dysfunction
sensory deficits
back pain
saddle anesthesia
sexual dysfunction
weakness or paralysis
paraplegia
105
cauda equina syndrome treatment
supportive care
if compression: immediate laminectomy <6 hrs
106
TNS cause, factors that increase risk and factors that do not increase risk
cause: patient positioning, myofascial strain and spasms
increase: lidocaine 5% risk, lithotomy position, outpt surgies, knee arthroscopy
do not increase: early ambulation, LA concentration and baricity
107
TNS signs and symptoms
pain in back and buttocks that spreads down both legs
trigger point injections: relieve muscle spasms
108
what are risks for epidural vein cannulation
multiple attempts
pregnancy
catheter type: stiffer catheters are harderr
trauma to epidural vein during block procedure
109
Unilateral epidural block
cause, solution
**cause**
* catheter too far, exiting epidural space through intervertebral foramen
**solution**
* pull the catheter 1-2cm and leave 3 cm remains in the epidural space
* reposition: lateral decubitus position: side not feeling numb facing downwards
* administer more anesthetic
* catheter replacement
110
symptoms of LAST
1-5: Analgesia
5-10: tinnitus, skeletal muscle twitching, numbness of lips and tongue, restlessness, vertigo, vertigo, blurred vision, hypotension, myocardial depression
coma
10-15: seizures loss of consciousness
15-25 coma, respiratory arrest
>25 cardiovascular collapse
111
LAST increases with
hypercarbia, hyperkalemia, metabolic acidosis
112
LAST decreases with
Hypocarbia, hyperkalemia, cns depressants
113
LAST CV toxicity
* decreases the heart automaticity
114
Key factors that determine the extent of cardiotoxicity
* LA affinity to voltage Na channel in the active and inactive states
* rate of dissociation form the receptor during diastole
115
Difficulty of cardiac resucitations for local anesthetics
Bupivacaine>levobupivacaine>ropivacaine>lidocaine
116
LAST Treatment
* give oxygen
* treat seizures: benzos, avoid propofol
* modified acls: cautious with epi (1mcg/kg), amiodarone
* lipid emulsion therapy
117
Epidural/spinal Hematoma is associated with
preexisting abnormailities in clotting hemostasis
traumatic or difficult needle placement
indwelling catheters and long term anticoag
118
cord ischemia reversible if laminectomy is performed in
< 8 hours
119
what is arachnoiditis
* inflammation of meninges associated with: nonapproved drug admin into intrathecal or epidural space
using non preservative free solutions
betadine contamination
* leads to extensive sclerosis of arachnoid membranes and constriction of vascular supply
120
Advantage of using pencil-point tip in a SAB
* drag fewer contaminants into subnormal tissue
* a click or pop can be sensed with a pencil point needle
* carry significantly less risk of PDPH
* pencil point needles are associated with less than a 1% risk of PDPH and a failure of about 5%
121
common problems encountered with SAB
* lack free flow csf when spining 360 degrees
* no swirl
* resistance with injection
* paresthesia
* blood instead of csf
* no block
* partial block
122
epidural need with most curvature (30 degrees), blunt tip is less likely to puncture subarachnoid space
Tuohy
123
Epidural needle with 15 degrees
Hustead
124
what epidural needle is preferred when catheter placement is difficult or angle is steep. 0 degree curvature
crawford
125
what epidural needle has 15 degree curve and has wings
weiss
126
recommended top up time from initial dose:
lidocaine:
2-chloroprocaine
mepivacaine
bupivacaine and ropivacaine:
lidocaine: 60
2-chloroprocaine: 45
mepivacaine: 60
bupivacaine and ropivacaine: 120
127
common problems encountered with epidurals
csf wet tap
paresthesia
cant thread the catheter
aspirate blood
postive test dose
false positive test done
