Week 12 Spinals, Epidurals, and Locals Flashcards
1
Q
Spinal and epidural are considered ________ _________.
A
Neuraxial Blocks
2
Q
In the history of epidural anesthesia, what occurred in the 1950s?
A
- Popularized epidural anesthesia in the 1950s
- Touhy Needle introduced in 1949
- Lidocaine available in 1950s
3
Q
In the history of epidural anesthesia, what occurred in the 1960s?
A
By the 1960s it was popular amongst the obstetric population
4
Q
Today neuraxial blocks are widely used for:
A
- Labor analgesia;
- Caesarian section;
- Orthopedic procedures;
- Perioperative analgesia
- Chronic pain management
(He said even Urology cases)
5
Q
Neuraxial blocks in anesthesia use (3)
A
- Alternatives to general anesthesia
or
- Used simultaneously with general anesthesia
or
- afterward for postoperative analgesia.
6
Q
Neuraxial techniques have proven to be safe when well managed. However, the is still risk of complications ranging from:
A
- self-limited back soreness to debilitating permanent neurological deficits and even death
7
Q
Benefits of neuraxial blocks:
A
Reduce the incidence of:
- Venous thrombosis & pulmonary embolism
- Cardiac complications in high-risk patients
- Bleeding & transfusion requirements & vascular graft occlusion
- Pneumonia & respiratory depression following upper abdominal or thoracic surgery in patients with chronic lung disease
- An earlier return of gastrointestinal function
8
Q
Epidural is the reversible chemical blockade of ________ ________ produced by the injection of a LA drug into the epidural space
A
neuronal transmission
It interrupts transmission of sensory, autonomic, and motor nerve fiber transmission in the anterior and posterior nerve roots
9
Q
Epidural anesthesia interrupts transmission of sensory, autonomic, and motor nerve fiber transmission in the _______ and _______ nerve roots.
A
anterior;
posterior
10
Q
More benefits of epidural anesthesia:
- Avoidance of larger doses of anesthetics and opioids
- amelioration of the _________ state.
- improved oxygenation from decreased splinting.
- enhanced ___________ (Hint: GI).
- suppression of ________ _________ response to surgery.
- ______-______ increases in tissue blood flow.
A
hypercoagulable
peristalsis
neuroendocrine stress
sympathectomy-mediated
11
Q
Epidural benefit:
Reduction of parenteral opioid requirements, which decreases – (4)
A
- Atelectasis
- Hypoventilation
- Aspiration pneumonia
- Reduction of ileus duration
12
Q
Postoperative epidural analgesia reduces the time to __________; and preserves _________ reducing cancer spread according to some studies
A
Extubation;
Immunity
13
Q
Benefits of epidural anesthesia in OB:
A
- Widely used for women in labor and during vaginal delivery.
- C-sections are most performed under epidural or spinal anesthesia: both blocks allow a mother to remain awake for the birth of her child.
- Some studies show it is less maternal M&M than GETA (largely d/t incidence of aspiration and failed intubation)
14
Q
Epidural Anesthesia advantages:
A
- Predictable
- Can provide a segmental blockade
- Reduce risk of thrombosis
- PT can remain fully conscious
- Analgesia into the post-operative period
15
Q
Epidural Anesthesia
disadvantages:
A
- May require 10-20 minutes to establish a level
- Sympathetic blockade
- Surgeon complains “It takes to long”
- Time-consuming to perform
16
Q
Vertebral column is made up of ____ Vertebrae
Cervical:
Thoracic:
Lumbar:
Sacral:
Coccygeal:
A
33
Cervical: 7 (C1-C7)
Thoracic: 12 (T1-T12)
Lumbar: 5 (L1-L5)
Sacral: 5 fused (S1-S5)
Coccygeal: 4 fused to form the coccyx
17
Q
T/F: Vertebrae differ in shape and size at the various levels
A
True
18
Q
____ cervical vertebra (_______)- lacks a body and has unique articulations with the base of the skull
A
1st
atlas
19
Q
______ cervical vertebra (_______)- has atypical articular surfaces
A
2nd
axis
20
Q
All _______ thoracic vertebrae- articulate with their corresponding _______.
A
12;
Rib
21
Q
_______ vertebrae- have a large anterior cylindrical body
A
Lumbar
22
Q
When all vertebrae are stacked vertically the hollow rings become the ________ _______ (where the cord and its coverings sit)
A
spinal canal
23
Q
Individual vertebral bodies are connected by :
A
intervertebral disks
24
Q
Spinal Ligaments- (superficial to deep):
A
- Supraspinous
- Interspinous
- Ligamentum flavum
- Posterior longitudinal
- Anterior longitudinal
25
The spinal canal contains the cord with:
- coverings (meninges)
- fatty tissue, and
- venous plexus
26
Meninges- 3 layers:
- pia mater,
- arachnoid mater and
- dura mater (contiguous with cranial counterparts)
27
meninge closely adherent to the spinal cord
Pia mater
28
meninge closely adherent to the thicker and denser dura mater
Arachnoid matter
29
Where is the CSF contained?
contained between the pia and arachnoid mater in the subarachnoid space
30
where is the Epidural space (potential space)?
within the spinal canal bounded by the dura and the ligamentum flavum
31
The spinal cord extends from the ____ to the _____ in adults.
and in children?
Extends from the **foramen magnum** to the **level of L1** in adults
In children the spinal cord ends at **L3** and moves up with age
32
Lower spinal nerves form the :
cauda equina (horse’s tail)
33
*Performing lumbar (subarachnoid) puncture below L1 in adults and L3 in children usually avoids potential needle trauma to the cord; damage to the _______ _________ unlikely*
cauda equina
34
MOA of neuraxial blockade:
Interruption of **efferent** autonomic transmission at the **spinal nerve roots**
**Sympathetic Blockade**
35
The physiological responses of neuraxial blockade
S/S:
decreased sympathetic tone/ unopposed parasympathetic tone.
drop in BP
decrease in HR
arterial vasodilation- decreased SVR
36
As a primary anesthetic, neuraxial blocks are most useful in:
- lower abdominal
- inguinal
- urogenital
- rectal
- lower extremity surgeries
37
Upper abdominal procedures such as gastrectomy have been performed with spinal or epidural anesthesia- but:
can be difficult to safely achieve adequate sensory levels for patient comfort
38
T/F: Epidurals are good choice for patients with coexisting pulmonary disease.
True :)
39
Pre-op considerations for neuraxial blocks:
- Discuss the plan with the surgeon.
- Discuss the proposed surgery and explain the epidural technique in detail.
- Do not coerce the patient into an epidural anesthetic
- Do a full pre-operative assessment and interview
40
Most important pre-op labs to have before epidural procedure?
Coags!!! Specially **platelets**
41
Informed consent for neuraxial block considerations:
- Make sure you document that you have discussed the advantages & disadvantages of the anesthetic
- Discuss risk
- **GA is plan B**
- Document
42
Pre-op meds considerations for neuraxial blocks:
- Pt should be NPO
- Do not over-sedate the patient
- OB patients are not sedated
- Midazolam (titrate to effect)
- Opioids
43
Epidural is indicated for (6)
- “balanced” regional/general anesthesia
- Pt has a full stomach
- Upper airway anomalies
44
Contraindications for neuraxial blocks: **absolute**
**Epi I RAP CHICAS**
- **I** nfection at the site
|
- **R** efusal from patient.
- **A** ortic/mitral stenosis or asymmetric septal hypertrophy
- **P** sychiatric disease - **Severe**
|
- **C** oagulopathy
- **H** erpetic infection
- **I** ncreased ICP
- **C** NS disease - Preexisting
- **A** llergy to LA
- **S**epticemia or bacteremia
45
Contraindications for neuraxial blocks: **relative**
**my Epi Relatives love CHOC MUSH**
- **C** lotting/blood abnormalities (Minor) ( ASA or mini heparin doses / Check coags ).
- **H** A (chronic) or backache
- **O** besity/ deformities of the spinal column
- **C** hronic HTN (Untreated)
- **M** ultiple attempts
- **U** mbilicus - surgeries above it.
- **S** urgery of unknown duration
- **H** IV infections
46
Neuraxial Block patient preparation:
- Baseline VS & Pt must have an IV
- Standard monitors
- Equipment to provide positive pressure ventilation
- Supportive meds
47
In the history of epidural anesthesia, what occurred in the 1950s?
- Popularized epidural anesthesia in the 1950s
- Touhy Needle introduced in 1949
- Lidocaine available in 1950s
48
Benefits of epidural anesthesia in OB:
- Widely used for women in labor and during vaginal delivery.
- C-sections are most performed under epidural or spinal anesthesia: both blocks allow a mother to remain awake for the birth of her child.
- Some studies show it is less maternal M&M than GETA (*largely d/t incidence of aspiration and failed intubation*)
49
In an epidural **midline** approach - what layers do you penetrate with needle?
- Skin
- Subcutaneous tissue and fat
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Epidural space
50
For an epidural you palpate the patient's back to find the:
and which sites do you use?
Superior aspects of the iliac crest and the spinous process
L4 or L4-5
Use the largest and most superficial interspace you can find
L2-3
(according to VP- we use L4 - L5)
51
Draw up the LA to be used for the skin wheal in a _____ ml ______ syringe
Draw ______ ml of **preservative free** saline into the ____ ml _______ syringe
3; plastic
2-3; 5ml glass
52
In an epidural: Raise a skin wheal with the ______ -gauge needle
27
53
Ligamentum flavum is normally _____ cm from the skin
4 cm
54
In an epidural **paramedian** approach - what layers do you penetrate with needle?
- Skin
- Subcutaneous tissue and fat
- Paraspinous muscle
- Ligamentum flavum
- Epidural space
55
With the Paramedian technique how do you point the needle?
Direct needle medially and cephalad
56
Touhy Needle (Epidural needle) characteristics:
- 3.5 inches long
- 17-18 gauge
- With inner stylet: prevents occluding the lumen with tissue.
- with rounded tip: prevent puncture of the dura and easier to thread the catheter
- Markings along the shaft of the needle are in **1 cm** increments
- 9 cm from the tip of the needle to the *proximal* edge of the hub
- 11 cm to the *distal* edge of the hub
57
Markings on the Epidural **Catheter**
1st. marking= _______ cm
Each marking after that is _____ cm
2nd double marking= _____cm
**Thick** mark is ______cm.
3rd triple mark is _______cm.
- 1st marking= 5 cm
- Each marking after that is 1 cm
- 2nd double marking= 10 cm
- **Thick** mark is 11 cm
*When inserted to this point you are at the tip of the needle in the epidural space*
- 3rd triple mark= 15 cm
**Single hole at the end vs multiple ports on its distal side**
58
Skin to Epidural Space:
_______ cm in 60% of patients
_______ cm in 25% of patients
_______ cm in 10% of patients
>________ cm in 5% of patients
- 4-6 cm in 60% of patients
- 2-4 cm in 25% of patients
- 6-8 cm in 10% of patients
- >8 cm in 5% of patients
59
Usually leave _____ cm of the catheter in the epidural space.
3-4 cm
60
Things to keep in mind with the epidural catheter: (4)
- When advancing the catheter, the patient may feel **transient paresthesia**
- Catheter may puncture the dura and you will get CSF (may not aspirate CSF).
- Be careful removing the needle with the catheter.
- An **antibacterial filter** is attached to the end of the catheter
61
T/F: A negative aspiration ensures you are not in a vessel or the subarachnoid space
False! - it does NOT
62
Test dose for epidural
and
what level of block would be produced if inadvertently injected in CSF?
3 ml of 1.5-2% Lidocaine with **1:200,000** epinephrine
This dose will only produce a **T10** block if injected in the CSF
63
What should you ask a patient during a test dose?
to report symptoms of “feeling different, ringing in the ears or metallic taste in the mouth”
64
During test dose, if it is an intravascular injection what symptoms would you see?
- Increase in HR of **15-20** bpm for 2-3 minutes
- Systemic toxicity- numb tongue, dizziness, ringing in the ears
65
During test dose, if it is a **subarachnoid injection** what symptoms would you see?
Immediate onset of **sensory** and **motor** block in the buttocks and lower extremities **(T10 block)**
66
During test dose, if injection is in the **subdural** what would happen?
Produces a **High** block
67
T/F onset of epidural is faster than the spinal
False - Epidural onset takes longer (~10- 20 mins)
68
Evaluation of patient after an epidural involves:
- After repositioning evaluate patient for 10-30 minutes
- Measure BP **every minute** for the first 3-5 minutes then **every 2-3 minutes** until the block is set.
- Determine the level of blockade every 2-3 minutes with an alcohol sponge and then a sharpened device until the level is set.
**Check level every 30-45 minutes**
- Evaluate BP, ECG, and pulse ox
69
The distribution of the LA in the epidural space is dependent on:
the volume injected
**Positioning will not aide in distribution of the local**
70
The primary objective of the **epidural is to block** the_________ fibers located in the ______ _______.
afferent;
dorsal roots
71
Site of action of Local:
- **Ultimate target are the spinal nerves & roots**
- The dura serves as a barrier to diffusion of Local
- Most is absorbed into the circulatory system some will stay in the epidural space and the rest will enter the spinal nerves and nerve roots
- The Local will spread horizontally and longitudinally once in the epidural space
72
Distribution of the LA
Blockade of fibers occurs quickly.
Blockade is ___ __________ higher than sensory
2 dermatomes
73
Distribution of the LA in epidural:
1. A quick drop in BP may be an early sign that a “_________” is setting up.
2. Rapid decrease in BP cause :
3. These effects will be accentuated in which patients:
1. spinal;
2. nausea or dizziness.
3. hypovolemic pt's
***Cardioaccelator fibers***
74
Distribution of the LA in epidural:
Temperature & Light Touch
- **Unmyelinated C & myelinated A-delta fibers**.
- Loss of these follows **autonomic blockade**.
- Assess with Alcohol sponge
- Loss of temperature correlates with **sensory loss**
- May report lower extremity feels **warm**
75
Distribution of the LA in epidural:
Initial Motor Impairment & Touch
- **Myelinated A-beta & A-gamma**.
- Follows loss of **temperature and touch** discrimination
- Onset of **motor weakness** and **impaired perception of *strong tactile*** stimulation
- Use a sharpened device or pinch method to assess level
76
Distribution of the LA:
Profound Motor & **Proprioception**
Myelinated A-alpha fibers
Profound motor block develops with loss of proprioception
Feel “Phantom Limb”
77
How to Assess motor block:
Lift shoulders of the bed (T6-T12)
Raise knees (L2-3)
Flex toes (L4-L5)
Dorsiflex feet (S1-S2)
78
Epidural Desired Level of Block
Will be determined by:
- The volume and concentration of drug.
and
- The level of the epidural catheter placement.
79
Injection of **10-15** ml of LA into the epidural space in the lumbar area will produce a ___________ level in the average sized patient
T7-9
80
What is an inadequate block and what can you do?
The concentration or volume of the drug may have been too weak to penetrate spinal nerves
If the block does not reach the desired level, you can give a **top off dose**:
- One-half of the initial volume can be reinjected
- Wait 10-15 minutes before reinjection
81
_________ is the key factor in the height of the block (in epidurals)
Volume
82
The guideline for dosing an epidural in adults is _________ ml per segment to be blocked.
Adjust the guideline for shorter patients (______ in.) or taller patients (__________in.).
1 - 2;
< 5 ft. 2;
> 6 ft. 2
'"**T10 block from L3-4 injection: 6-12 ml of local anesthetic. **
83
Epidural:
The ______, _______, and _______ _______ administered will vary with the level and duration of block desired.
The type, volume, and total dose
84
LA drugs **reversibly** interrupt nerve impulse conduction by interfering with_________ conductance.
sodium ion
85
Local Anesthetic
Potency
- Equal to lipid solubility
- Higher lipid soluble, the more readily it penetrates neuronal membranes
- Better able to penetrate **A-alpha** motor fibers
86
Local anesthetic
Rate of onset:
- Determined by pKa
- **Weak bases**
- pKa near physiologic ph will move more readily into nerve membranes
**The neutral (non-ionized) form is most readily able to penetrate the neuronal membrane**
87
Local anesthetic
DOA:
- Determined by potency and protein binding
- Highly protein-bound agents are less available for systemic absorption
88
Most common LAs:
- Bupivacaine (Marcaine)
- Ropivacaine
- Lidocaine
- Mepivacaine
- 2-chloroprocaine
89
Distribution and Uptake of LA
The spinal nerves in the epidural space are larger and covered by _______ and ______ matter.
It takes ________ times the dose **(mass)** of LA to accomplish the same blockade as a spinal
arachnoid; dura
6-8
90
what three factors influence the level of DOA of LA in an **epidural**?
and which has biggest influence of **level** of blockade
1. volume: larger = greater vertical spread.
2. dose: increase= intense analgesia/ prolonged DOA.
3. concentration: increase= faster onset/ more intense block
___________________
**Volume**
91
Vasoconstrictors such as Epinephrine can help:
Be a marker for intravascular injection
Prolong duration of action of Locals
92
effect of vasoconstrictors on the DOA of LA
prolong
93
epi in LA is usually a __________ dose
1:200,000
94
The closer the injection site is to the spinal nerve to be blocked, the _______ rapid the onset of analgesia
more
95
Slowly titrate LA into the epidural space ( _____ ml increments every _____`)
Pt. may complain of?
3-5ml every 60 seconds.
Headache (HA)
**this does not detect intravascular injection**
96
T/F: **level and duration of action? (For epidurals)
1. Patient position does NOT affect it.
2. Extremes of age affects spread.
3. Height does not affect the dose.
True :)
False
True
97
for epidural LA dose, what would you do for each population
elderly
obese
Parturient
E- half dose
O- decrease d/t larger cephalad spread
P- 1/3 dose needed from non-pregnant (d/t engorgement of epidural veins/ hormones).
98
If the pt. has an adequate level but not a solid block, redose with a **top-up dose** or
20% of the initial volume
**During the anesthetic do not allow the level of blockade to recede**
99
If the pt. has an adequate level but not a solid block and they are redosed, what will happen to the intensity and height of the block
intensity increase
height remains the same
100
if epidural level has regressed 1-2 dermatomes, redose with:
1/2 to 1/3 initial volume.
101
Dermatome level for C- section:
T4 level ( nipple area )
102
Dermatome level for knee or hip sx:
T10 ( umbilicus )
103
Dermatome level that is considered dangerous area:
C4- C5, *even T1 ( Cardiac accelerators ).
104
CNS S/S of LA toxicity (7)
**Nobody Drinks Like Drew Drinks Vodka And Club**
1. numbness of tongue and lips
2. dizziness
3. lightheadedness
4. disorientation
5. drowsiness
6. visual & auditory disturbance
7. convulsions
105
CV S/S of LA toxicity (3)
1. ecg changes
2. CV depression
3. cardiac arrest
106
what is it called when an intended epidural is given into spinal space
high spinal and its very dangerous
107
treatment for CV collapse from LA toxicity
IV 20% lipid emulsion
108
in LA toxicity, what 4 meds should be avoided
1. vasopressin
2. Ca2+ channel blocker
3. beta-blocker
4. LAs
109
spinal are the reversible chemical blockade of **neuronal transmission** produced by injection of a LA into CSF contained in the _______
subarachnoid space
110
t or F: the advantages of spinals are similar to epidurals
T
**only differences is the smaller dose of LA = less toxicity**
111
spinals produce a (sympathetic/parasympathetic) blockade 100% of the time, which can cause?
sympathetic
hypotension
112
what can be given prophylactically for a spinal
phenylephrine
113
T or F: spinal anesthesia is a good choice for major intraabdominal procedures
F- not a good choice
Good choice for procedures of the mid to lower abdomen and lower extremity
114
in pts with pulmonary disease, spinal level should not exceed what level
T4
115
T or F: spinal anesthesia is a good choice for major intraabdominal procedures
F- not a good choice
116
9 absolute contraindications for spinal
1. pt refusal
2. severe psych disease
3. CV disease
4. severe hypovolemia
5. CNS disease
6. blood clotting anomalies
7. infection at site
8. septicemia/bacteremia
9. allergy to LA
117
10 relative contraindications of spinal
1. HIV
2. Surgery of unknown duration
3. untreated chronic HTN
4. procedure above the abdomen
5. obesity
6. deformity of spinal column
7. chronic HA/backache
8. bloody tap
9. multiple attempts
10. minor blood clotting abnormalities
118
procedural site for spinal
one of four intervertebral spaces L2-S1 (popular site L2-3 or L3-4)
119
if pt is in lateral position for spinal insertion, would surgical side be up or down if using a hyperbaric solution
surgical side down!
120
when preparing a spinal, what two structures will differe between midline and paramedian approach
midline- supraspinous ligament & interspinous ligament
paramedian- paraspinous muscle & ligamentum flavum
121
how often should you check BP after spinal admin
Q3-5 minutes until block is set
122
how frequently should you assess the progress of the spinal block after administration until block achieved and then how frequently after that
every mintute until block achieved
Q30-45 min
123
two ways to test if spinal is working
1. Alice/hemostats?
2. alcohol sponge
124
earliest sign spinal is working
drop in BP followed by nausea and dizziness
125
after spinal admin, loss of temp and light touch signals that what fibers are blocked . How can we assess this
C and A-delta
alcohol sponge
**loss of these follows autonomic blockade**
126
in spinal admin, motor impairment and touch and managed by what fibers
A-beta and A-gamma
127
which comes first in spinal
loss of motor & touch OR loss of light touch and temperature
loss of light touch and temperature
128
:)
129
which dermatomes are you assessing if you ask pt to dorsiflex feet
S1-S2
130
which dermatomes are you assessing if you ask pt to flex his toes
L4-L5
131
which dermatomes are you assessing if you ask pt to raise their knees
L2-L3
132
which dermatomes are you assessing if you ask pt to lift shoulders off bed
T6-T12
133
a block at S2-S5 is referred to as a ___________.
**There (is/is no) effect of ANS**.
Surgical anesthesia is limited to ________, _________, & __________
saddle block
is no
perineum, perianal, genitalia
134
A block at T10 (umbilicus) is referred to as a ________.
It blocks ______ &__________.
it produces _________ & __________.
What surgeries is it good for?
low spinal
s1-5 & L1-5
vasodilation and lowers BP
gynecologic, vaginal delivery, lower extremity surgery, TURP, cysto
(**C-section is T4**)
135
A block at ______ is referred to as a high spinal.
It is used for ___________ surgery though the patient can still feel traction.
It can cause (vasodilation/vasoconstriction) and block _______________ fibers
T4 (nipple)
upper abdominal
vasodilation
cardio accelerator
136
A block at C8, referred to as __________,
is a (high/low/total) spinal.
Pt may experience ________ that can lead to ____ &________.
little finger
total
difficulty breathing
respiratory & cardiac arrest
**This is bad news friend** you better grab airway eqt.
137
which two spinal needles are "puncturing" needles
Quincke & whittacre
138
name the 4 spinal needles
Quincke
Whittacre
Sprotte
Pencan
139
what causes PDPH and how can it be prevented/exacerbated
CSF leak
choice in needle size
- large (20 -22G) = more CSF but easier to use
- smaller (25- 26G) = less CSF but more difficult to use
140
LA solutions > 5% concentration are linked to ___________
neurotoxicity
141
very (large/small) amounts are needed for spinals
**SMALL**
142
T or F: LAs are the safest anesthetic we have and as a result are completely risk free
F- *nothing* is risk free
143
Which LA does this describe for spinal use:
2 ml ampule of 5% solution premixed with 7.5% dextrose (*hyperbaric*). This mixtures has a risk for **cauda equina syndrome**
A. Lidocaine
B. Procaine
C. Tetracaine
D. Bupivacaine
A
144
Which LA does this describe for spinal use:
2 ml ampule of 10% solution. *Short* DOA, low potency.
A. Lidocaine
B. Procaine
C. Tetracaine
D. Bupivacaine
B
145
Which LA does this describe for spinal use:
2 ml ampule of 1% solution. Provides a more profound block than the other three listed
A. Lidocaine
B. Procaine
C. Tetracaine
D. Bupivacaine
C
146
Which LA does this describe for spinal use:
2 ml ampule of 0.75% with 8.25% dextrose (*hyperbaric). The onset is 3-5 minutes. You must use a *filtered* needle with this
A. Lidocaine
B. Procaine
C. Tetracaine
D. Bupivacaine
D
147
Bupivacaine has less motor block than
tetracaine
148
spinal dose for *normal* duration total knee or hip replacement for T10 level
Lidocaine
Bupivacaine
L- 50-75 mg (of a 5% solution = 1-1.5 ml)
B - 8-12 mg (of a 0.75% soltuion = ~1-1.6 mL)
149
how to we extend normal duration of spinal dose if, for example, you're with a slow surgeon
epi-wash (100 mcg)--> extends ~ 1 hour
(0.1 - 0.2 mg)
150
spinal dose for *normal* duration total knee or hip replacement for T4 level
Lidocaine
Bupivacaine
L- 75-100 mg (of a 5% solution = 1.5-2 ml)
B - 14-20 mg (of a 0.75% soltuion = ~1.8-2.6 mL)
151
what LA is mainly used for D&C
Chloroprocaine 3% (VERY quick acting and short DOA)
152
T or F: vasoconstrictors prolong the action of bupivacaine
F- do not prolong the *action* of bupivacaine... its just vasoconstricting to its not being taken away as quickly
153
T or F: vasoconstrictors will prolong DOA of ester LAs
T
154
2 vasoconstrictors used for spinals
epinephrine
phenylephrine (less common)
155
Vasoconstrictors in the spinal space can: (6)
- constrict blood vessels at the site and slow absorption of LA
- produce analgesia
- prolong DOA of **ester** LA ( tetracaine, procaine).
- does prolong action of **lidocaine**
- does not prolong action of *bupivicaine*
- does not affect spread of block.
156
intrathecal opioids will not produce analgesia. How can better anesthesia be provided/achieved
administer with LA
157
Fentanyl Intrathecal Opioid:
Dose:
S/E:
Onset:
Duration:
15-25 mcg
Higher doses: resp. depression, itching , and urinary retention
5- 10 minutes
2- 4 hours.
158
Duramorph is :
Onset:
Dose:
DOA:
Morphine (**preservative-free**)
- 60 - 90 minutes
- 0.1- 0.5 mg
- Profound analgesia for 18-27 hours.
**most commonly used**
159
intrathecal fentanyl and duramorph dose
F- ~ 20 mcg (15-25 mcg)
D- 0.15 mg (common in *OB*)
160
about how long should spinal last
~ 2 hours
161
3 most important factors for determining distribution of LAs for spinal
1. baracity
2. pt position during/just after
3. dose of LA
162
density of CSF =
1.004- 1.008
163
determines where spinal LA will distribute
Baracity
164
solution is hyperbaric... what is its density in relation to CSF
>CSF
>1.008
**most commonly used** **SINKS**
165
solution in hypobaric... what is its density in relation to CSF
< CSF
< 1.008
**FLOATS** up to the least dependent area. Good for lateral position sx.
166
Li
167
what is used to make a solution hyperbaric
dextrose
168
you want to achieve a saddle block... what baracity LA will you adminster
hyperbaric
169
T or F: you can achieve a high spinal after an isobaric solution LA administration by placing pt in trendelenberg
F- isobaric do **NOT** spread with position changes and are ideal when **repositioning may be required**
**Limited clinical application/ Difficult to obtain a high level**
170
spinal level normally fixed in ________ minutes of positioning patient.
5-10
**most evident with hyperbaric solutions**
171
4 CV complications following a spinal
1. block sympathetic fibers
2. block cardioaccelerator fibers
3. cause hypotension/bradycardia
4. BP decrease by 15-20% in most healthy pts
172
3 ways to treat hypotension following spinals
1. prevent with preload/prophylactic admin of 1-2L crystalloids
2. supplementary O2
3. treatment (slight trendelenberg, bolus crystalloid, ephedrine 5-10mg IV)
173
S/S of PDPH
N/V
photophobia
tinnitus
dizzy
cranial nerve palsies
**symptoms are postural**
174
3 treatment therapies for PDPH
1. resolves in 5-7 days
2. conservative therapy x24 hours
3. epidural blood patch
175
when administering an epidural blood patch for PDPH, where should you adminsiter it
blood moves cephalad so one interspace below
176
all LAs are weak (acids/bases)
Bases
177
how are LAs classified
according to structure
178
for amide LAs, the amine group is (hydrophobic/hydrophilic) and the aromatic end is (lipophobic/lipophilic)
hydrophilic
lipophilic
179
amides metabolized by
microsomal P-450 system
180
Put in order: amide LAs order of metabolism
ropivacaine
lidocaine
Prilocaine
bupivacaine
mepivacaine
prilocaine>lidocaine>mepivacaine>ropivacaine>bupivacaine
181
ester LAs metabolized by
pseudocholinesterases, hydrolysis is very rapid
182
procaine and benzocaine is metabolized by ______
PABA (p-aminobenzoic acid)
183
CSF lacks esterase enzymes so termination of action of ester depends on
redistribution to bloodstream
184
short cut way to tell the difference bewteen amides and ester LAs
I before C = Am**I*des
185
name some amide LAs
- bupivacaine
- lidocaine
- ropivacaine
- etidocaine
- mepivacaine
186
name some ester LAs
cocaine
procaine
tetracaine
187
_______ end of ester LA is lopohilic and penetrates lipid bilayer of nerve membrane
aromatic
188
_________ part of amide LA is hydrophilic and remians of either side of nerve membrane
hydrophilic ring
189
which is hydrophobic and which is hydrophilic (the ends only)
190
allergy or cross sesntivity occurs with (amide/ester) linkage
ester
191
Nerve fibers classified according to what 3 things
1. size
2. conduction velocity
3. function
192
Ester LAs are rapidly metabolized in plasma by __________ into the metabolite __________. Amides are slowly destroyed by ______________
cholinesterase
PABA
liver microsomal P450 enzymes
193
Na+ channels are membrane-bound proteins composed of ________ subunits and ________ subunits. LAs bind to a specific region on (alpha/gamma) subunits and inhibit membrane (depolarization/repolarization), thus inducing anesthesia
1 alpha
2 betas
alpha
depolarization
194
(transmission/transduction) of electrical impulses along nerve membrane signal (transmission/transduction) along nerve fibers
transmission
transduction
195
sensitivity of nerve fibers to LA is determined by _________, __________, and other factors
axonal diameter
myelination
196
RMP = _________ by active transport and passive diffusion. Na+/K+ pump transports ___ Na+ out of cell for every ____ K+ into cells
-60 to -70 mV
3
2
197
onest of action of LA depends on what two things
While the DOA of LA depend on what two things
**ONSET:** lipid solubility & pKa
**DOA:** lipid solubility & potency
198
T or F: pH is pKa at which fraction of ionized and nonionized drug is equal
F -- pKa is pH at which....
199
Vasoconstrictors such as Epinephrine can help:
Be a marker for intravascular injection
Prolong duration of action of Locals
200
less potent & less lipid soluble have (slower/faster) onset than more potent more lipid soluble agents
faster
201
Quick summary of LAs **MOA**
- slows down speed/stops generation of AP
- bind to Na+ channels
- inhibit Na+ influx in the neuronal cells
202
3 factors affecting LAs action
1. lipid solubility ]
2. influence of pH
3. vasoconstrictors
203
T or F: epinephrine prolongs a bupivacaine block by increasing the volume of bupivacaine present in space
F -- literally the slopiest written question to date so my apologies
epinephrine **vasoconstricts** the vessels which decreased the rate of systemic absorption *So That (VP voice)* the local hangs out a bit longer :)
204
increased lipid solubility = (slower/faster) nerve pentration & onset of action
faster
205
A. a lower pKa (7.6-7.8) is (slower/faster) acting
B. give examples of low pKa anesthetics
C. a higher pKa (8.1-8.9) is (slower/faster) acting
D. B. give examples of higher pKa anesthetics
A. faster
B. lidocaine & mepivacaine
C. slower
D. procaine, tetracaine, & bupivacaine
206
t or F: vasoconstrictors synergize the vasoconstricting effects of LAs
F -- vasoconstrictors **antagonize** the **vasodilating** effects of LAs
207
2 medications that affect LA action
opioids -- synergistic analgesia & attenuation of C-fibers
a-2-adrenergic agonist -- clonidine inhibitory effect on peripheral nerve conduction & analgesia via supraspinal/spinal adrenergic receptors
208
rate of systemic absorption of LAs is related to ______ & ________
blood flow & vascularity
209
decreased absorption of LAs with the use of vasoconstrictors (reduces/increases) peak concentration of LA in blood, (enhances/ inhibits) quality of anesthesia, and (shortens/prolongs) DOA and (increases/limits) toxicity
reduces
enhances
prolongs
limits
210
pharmacokinetics of LAs determined by what 3 things
1. tissue perfusion
2. tissue blood partition coefficient
3. tissue mass
211
early S/S of CNS LA toxicity
late S/S of CNS LA toxicity
excitatory S/S
circumoral numbness
tongue paresthesia
dizziness
tinnitus
blurred vision
___________
clonic-tonic seizures
___________
restlessness, agitation, nervousness
**Highly lipid soluble LA produce seizures at lower blood concentration**
212
disadvantages of spinal anesthesia:
- Hypotension
- Intense motor blockade that may last for hours post-op
- "takes too long"
213
T or F: spinal anesthesia is a good choice for major intraabdominal procedures
F- not a good choice
Good choice for procedures of the mid to lower abdomen and lower extremity
214
Fentanyl Intrathecal Opioid:
Dose:
S/E:
Onset:
Duration:
15-25 mcg
Higher doses: resp. depression, itching , and urinary retention
5- 10 minutes
2- 4 hours.
215
Respiratory effects of LAs:
Relax bronchial smooth muscles
Phrenic nerve paralysis
Depression of hypoxic drive
216
Cardiovascular effects of LAs: (7)
- Depress myocardial automaticity
- Unintentional IV injection of **bupivacaine** may produce severe CV toxicity
- Left ventricular depression, AV block, arrhythmias
- Decreased cardiac excitability and contractility
- Decrease conduction rate
- **Increased refractory** rate
- Hypotension
217
Local Anesthesia Toxicity
Related to absorption from the site
(Review LAST s/s)
218
The distribution of LAs occurs in 3 phases describe:
Highly vascular tissue (lungs and kidneys) then less vascular tissue (muscle and fat), then drug is metabolized
219
Major CV toxicity requires _____ times the local anesthetic concentration in blood as that requires to produce seizures
3
