Neuraxial anesthesia III Flashcards
(103 cards)
1
Q
what do these terms mean: hyperbaric, hypobaric, isobaric?
A
hyperbaric = more dense than CSF
isobaric = equal density to CSF
hypobaric = less dense than CSF
2
Q
what spinal drugs are hyperbaric?
A
- bupivacaine 0.75% in 8.25% dextrose
- lidocaine 5% in 7.5% dextrose
- tetracaine 0.5% in 5% dextrose
- procaine 10% in water
3
Q
what spinal drugs are isobaric?
A
- bupivacaine 0.5-0.75% in saline
- lidocaine 2% in saline
- tetracaine 0.5% in saline
4
Q
what spinal drugs are hypobaric?
A
- bupivacaine 0.3% in water
- lidocaine 0.5% in water
- tetracaine 0.2% in water
5
Q
in a supine position, at what level should hyperbaric LAs be expected to settle?
A
T6 and S2
falls to the lowest points
6
Q
in a supine position, at what level should hypobaric LAs be expected to settle?
A
C3 and L3
rises to the highest points
7
Q
T/F: No LA metabolism occurs in the CSF
A
True
all are eliminated by reuptake in vessels and fat
8
Q
what are the doses for spinal bupivacaine?
A
0.5-0.75%
T10 dose: 10-15 mg
T4 dose: 12-20 mg
9
Q
what is the onset and duration of spinal bupivacaine?
A
onset = 4-8 mins
duration plain = 130-220 mins
w/ epi = +20-50% longer
10
Q
what is the spinal dose for spinal levobupivacaine?
A
0.5%
T10 = 10-15 mg
T4 = 12-20 mg
11
Q
what is the onset and duration of spinal levobupivacaine?
A
onset = 4-8 mins
plain = 140-230 mins
12
Q
what is the spinal dose for spinal ropivacaine?
A
0.5-1%
T10 = 12-18 mg
T4 = 18-25 mg
13
Q
what is the onset and duration of spinal ropivacaine?
A
onset = 3-8 mins
duration = 80-210 mins
14
Q
what is the dose for spinal 2-chloroprocaine?
A
3%
T10 = 30-40 mg
T4 = 40-90 mg
15
Q
what is the onset and duration of spinal 2-chloroprocaine?
A
onset = 2-4 mins (most rapid)
duration = 40-90 mins (shortest acting)
16
Q
what is the dose for tetracaine?
A
0.5-1%
T10 = 6-10 mg
T4 = 12-16 mg
17
Q
what is the onset and duration of tetracaine?
A
onset = 3-5 mins
duration plain = 90-120 mins
w/ epi = +20-50% longer
18
Q
eipdural LA spread occurs in what direction?
A
cephalad and caudad
19
Q
what does incremental dosing of 5 ml avoid with epidurals?
A
- Accidental “High spinal”
- Hypotension from rapid autonomic blockade (cardiac arrest)
- LAST
20
Q
what are the concentrations for 2-chloroprocaine? which is used for surgical anesthesia?
A
2% and 3%
3% for surgical anesthesia
21
Q
what class of LA is 2-chloroprocaine? what is it metabolized by?
A
ester
plasma cholinesterase
22
Q
what is alkalinization? what is its purpose?
A
- Adding NaHCO3 (1 mEq/10 mL of local anesthetic)
- makes LA more basic + increase non-ionized form
- Increases the rate of diffusion of the drug
- Increases the speed of onset of the block
23
Q
which LA is only used for epidurals? which is only used for spinals?
A
Lidocaine = epidural only
tetracaine = spinal only
24
Q
epinephrine is commonly added to which 2 LAs for spinals?
A
bupivacaine w/ epi
tetracaine w/ epi
25
what are the drugs and their concentrations for epidurals?
* 2-chlorprocaine = 3%
* lidocaine = 2%
* ropivacaine = 0.1-0.75%
* bupivacaine = 0.0625-0.5%
* levobupivacaine = 0.0625-0.5%
26
the order of onset and duration from **fastest to slowest** for epidurals
* 2-chloroprocaine = 5-15mins/30-90 mins
* lidocaine = 10-20 mins/60-120 mins
* ropivacaine = 15-20 mins/140-220 mins
* bupivacaine = 15-20 mins/160-220 mins
* levobupivacaine = 15-20 mins/ 150-225 mins
27
why is 2-chloroprocaine the fastest acting despite its basic pKa?
highest concentration of 2-3%
28
what is the inital volume of epidural LA when injected into L4 and desired level is T10?
6 segment above L4-T10
**6-12 ml of LA** must be injected to reach T10 (1-2 ml per segment)
29
if after 120 mins, the level of epidural anesthesia has dropped **2 segments**, how much volume of LA is given to re-establish appropriate block?
top-up dose = **50-75% of initial dose** when there is ***at least a 2 segment drop***
initial dose = 6-12 ml
top-up dose = **3-6 ml**
30
size of the epidural space is ____ in the thorax than in the lumbar area
**smaller**
larger in lumbar area
31
what determines block density in epidurals?
drug concentration
(i.e. 3% vs 2%)
32
what are the neuraxial adjuncts?
* **opioids** (Sufentanil, Fentanyl, and Morphine)
* **alpha-2 agonists** (Dexmedetomidine IV or IT*, Clonidine)
* **vasopressors** (epinephrine, phenylephrine)
33
T/F: opioids extend post-operative analgesia, duration, and density of block
**False**
Opioids do not extend duration of block
Extends only post-op analgesia and density
34
T/F: dexmedetomidine and clonidine both extend post-op analgesia, duration, and density of block
**True**
35
Vasopressors only extend ___________
**duration**
No effect on density or analgesia
36
why is epinephrine a good adjunct to epidural LAs?
accidental intravenous infiltration will result in severe tachycardia
37
what do opioidse target in the spinal cord?
substantia gelatinosa of dorsal horn
lamina II
38
opioids reduce neurotransmission by ____ cAMP, ____ Ca++ conductance and ____ K+ conductance
opioids reduce neurotransmission by **decreased** cAMP, **decreased** Ca++ conductance and **increased** K+ conductance
39
what are the hydrophilic opioids? what is their onset and duration?
**morphine**
**hydromorphone**
**meperidine**
slow onset 30-60 mins (lasts 6-24h)
40
what are the lipophilic opioids? what is their onset and duration?
**fentanyl
sufentanil**
rapid onset 5-10 mins (lasts 2-4h)
41
how does the spread in CSF compare between hydrophilic and lipophilic opioids?
**hydrophilic** = wide spread, larger pain relief, more rostral spread
**lipophilic** = limited spread, less rostral spread
42
which class of opioid has the most systemic absorption?
lipophilic opioids (fentanyl, sufentanil) highly absorbed by body
results in shorter duration
43
which class of opioid is most dangerous due to respiratory depression?
**hydrophilic**
respiratory depression occurs late (when back on the floor or D/C home)
44
intrathecal and epidural dose for sufentanil?
intrathecal = 5-10 mcg
epidural = 25-50 mcg
epidural infusion = 10-20 mcg/hr
45
intrathecal and epidural dose for fentanyl?
intrathecal = 10-20 mcg
epidural = 50-100 mcg
epidural infusion = 25-100 mcg/hr
46
epidural dose for hydromorphone?
epidural = 0.5-1 mg
epidural infusion = 0.1-0.2 mg/hr
47
intrathecal and epidural dose for meperidine?
intrathecal = 10 mg
epidural = 25-50 mg
epidural infusion = 10-60 mg/hr
48
intrathecal and epidural dose for morphine?
intrathecal = 0.25-0.3 mg
epidural = 2-5 mg
epidural infusion = 0.1-1 mg/hr
49
epidural administration of opioids diffuse where?
diffuses into **fat**, **CSF**, and **bloodstream**
50
what is the treatment for opioid induced pruritus?
* Benadryl 25-50 mg IV
* Naloxone 0.1 mg IV (best)
* Buprenex (mixed agonist/antagonist)
51
what drugs are used for pruritus prophylaxis?
* Minimize the dose of morphine < 300 mcg
* Ondansetron 4 mg IV
* **Nubain** 2.5-5.0 mg IV
52
what is the naloxone dose to treat apnea secondary to opioids?
naloxone 0.1-0.2 mg IV
53
what is the treatment for nausea and urinary retention secondary to opioids?
* Ondansetron (5 HT antagonist)
* Naloxone 0.1 mg
* Phenergan 12.5- 25 mg IM
* Morphine < 300 mcg
54
how often does urinary retention occur with opioid adjunct?
30-40%
55
alpha-2 agonists ____and ____ block by 1 hour
intensifies
prolongs
56
most common side effects of alpha-2 agonist adjunct?
Hypotension, bradycardia and sedation
57
dose for dexmedetomidine? clonidine?
dexmedetomidine = 3 mcg
clonidine = 15-45 mcg
58
addition of vasoconstrictor to what LA causes profound increase in duration?
tetracaine
59
addition of vasoconstrictor to bupivacaine and lidocaine causes
variable increase in duration
60
dose for epinephrine and phenylephrine adjunct?
epinephrine = 0.2-0.3 mg
phenylephrine = 2-5 mg
61
symptoms of epidural hematoma?
* Lower extremity weakness, numbness.
* Low back pain.
* Bowel and bladder dysfunction.
62
what is the treatment for epidural hematoma with complications?
surgical laminectomy within 8 hrs
63
what is primary vs secnodary anticoagulation?
primary = prevention of first event
secondary = prevention of recurrence
64
how many days is aspirin held for moderate-high risk procedures?
4-6 days
all ASA doses
65
NSAIDS should be held for how long before a high risk procedure?
hold or 5 half-lives
66
what intermediate risk procedures should we hold NSAIDS?
cervical epidural steroid shot (cervical ESI)
stellate ganglion block
67
what are high cardiac risk procedures?
* Emergency surgeries (especially in elderly patients)
* Open aortic surgeries
* Peripheral vascular surgeries
* Long surgeries with significant volume shifts and/or blood loss
68
what are intermediate cardiac risk procedures?
* Carotid endarterectomy
* Head and neck surgeries
* Intrathoracic or intra-abdominal surgeries
* Orthopedic surgeries
* Prostate surgery
69
what are low cardiac risk procedures?
* Endoscopic procedures
* Cataract surgery
* Superficial surgeries
* Breast surgeries
* Ambulatory surgeries
70
name the drugs and their class that are held for 4-8 hrs before surgery
glycoprotein IIB/IIIA antagonists:
**tirofiban (aggrastat)**
**eptifibatide (integrilin)**
71
which glycoprotein IIB/IIIA antagonist must be held 24-48 hrs before surgery?
abciximab (ReoPro)
72
name the thienopyridine derivative drugs and when they should be held before surgery
* Clopidogrel: Hold for 5-7 days.
* Prasugrel: Hold for 7-10 days.
* **Ticlopidine: Hold for 10 days.**
73
heparin should be held for how long before surgery?
* Low-dose (< 5,000 U): Hold 4-6 hours.
* Higher-dose (≤20,000 U daily): Hold 12 hours.
* Therapeutic dose (>20,000 U daily or in pregnant patients): Hold 24 hours
74
UFH greater than how many days needs a platelet count before neuraxial blockade?
* > 4 days
75
heparin inhibits which factors?
2 ,9, 10, 11, 12 (intrinsic)
76
LMWH should be held for how long after a prophylactic dose?
12 hours
77
LMWH should be held for how long after a therapeutic dose?
24 hours
78
how long should warfarin be held? what is the goal INR?
hold for 5 days
INR < 1.5
79
T/F: tPA is an absolute contraindication to neuraxial anesthesia
True
80
DOACs should be held how long before neuraxial anesthesia?
72 hours
81
can neuraxal anesthesia be performed if the patient is taking garlic, gingko, or ginseng?
yes, as long as not on any other anticoagulants
82
what are the DOACs? what do they do?
* Apixaban (Eliquis),
* Betrixaban (Bevyxxa),
* Edoxaban (Lixiana),
* Rivaroxaban (Xarelto),
* Dabigatran (Pradaxa)
* inhibit factor 10a
83
what are possible complications to neuraxial?
* Post dural puncture headache
* paresthesia
* failed spinal
* post-spinal bacterial meningitis
* cauda equina syndrome
* transient neurologic symptom
* retained catheter fragments
* blood in the epidural catheter
* unilateral block
* LAST
* epidural/spinal hematoma
* arachnoiditis
84
why does PDPH occur?
* Failure of a dura puncture site to properly “seal over” once breeched by a needle
* Continuous leak of CSF causes an overall reduction in CSF volume
* This leak lowers the pressure in the brain area, causing the brain to sag slightly and stretch the surrounding membranes, leading to a headache.
85
what are symptoms of PDPH?
* Headache that feels **worse** when **sitting** or **standing** and **better** when **lying down**.
* Headache occurs **2-3 days** post puncture.
* The headache is usually felt from the forehead to the back of the head. (**Frontal-Occipital**)
* Other possible symptoms include nausea, sensitivity to light, double vision, and ringing in the ears.
86
risk factors for PDPH?
* Being **younger**.
* Being **female**.
* Being **pregnant**.
* Using a needle with a **cutting tip**.
* Using a **large diameter** needle.
* Using **air** for LOR with epidural.
* Positioning the needle **perpendicular** to the spine's long axis.
87
what are treatments for PDPH?
* Bed rest
* NSAIDs
* Caffeine
* Epidural Blood Patch
* Sphenopalatine Ganglion Block
88
epidural blood patch involves?
* injecting patient's own blood (10-20cc) into epidural space
* 90% success rate
* if x2 patches are unsuccessful, consider other causes of headache
89
Sphenopalatine Ganglion Block (SPG Block) involves?
* cotton swab soaked with 1-2% lidocaine or 0.5% bupivacaine
* swab inserted into nose to the back of throat wall
* sphenopalatine ganglion block
90
when is epidural blood patch typically done?
48 hours after dural puncture
91
what is paresthesia caused by neuraxial? how is it managed?
* Needle injury from Needle and Catheter
* Redirection of needle is indicated when paresthesia occurs
92
when might the provider conclude that a failed spinal has occured?
15-20 minutes with no signs of blockade
consider MAC or general anesthesia
93
what is the most common bacteria involved in post spinal bacterial meningitis?
streptococcus viridians
found in the mouth and hands
94
what is the most recommended skin prep for neuraxial?
alcohol and chlorhexidine
95
what is cauda equina syndrome? what are risk factors?
* compression or dysfunction of the cauda equina (horse's tail)
* 5% lidocaine in SAB (< 2% recommended)
* microcatheters inject LA only in localized area
* whiticare 25/26 needle
96
what are symptoms of cauda equina syndrome?
* Serious neurologic complication that can be permanent
* **Bowel and Bladder Dysfunction**
* **Sensory Deficits**: Loss of feeling in the legs or feet.
* **Back pain**
* **Saddle anesthesia**
* **Sexual dysfunction**
* **Weakness or Paralysis**
* Can lead to **paraplegia** (late sign)
97
what is the treatment for cauda equina with compression?
emergent laminectomy <6hrs
98
what is TNS? causes?
TNS is temporary pain, numbness, tingling, or weakness in the lower back, buttocks, or legs following the use of local anesthetics
causes: 5% lidocaine, surgical positions, outpatient surgeries, knee arthroscopy
99
pain that starts 6-36 hours after surgery and lasts for 1-7 days is likely
transient neurologic symptoms
100
what is the treatement for TNS?
NSAIDs
trigger point injections
101
what position should the patient be in when removing an epidural cath?
same as insertion position
lateral decubitus
102
what intervention is done when blood is in the epidural catheter?
Slightly pull back the catheter and flush it with saline
Continue this until no more blood is drawn or if the catheter can't be adjusted further safely
103
