Neuraxial Anesthesia Flashcards
(138 cards)
1
Q
What is Neuraxial Anesthesia?
A
Spinal
Epidural
Caudal (mostly peds)
2
Q
Why use Neuraxial Anesthesia?
A
- -Alternative to general anesthesia
- -Can be used in conjunction with GA
- -Post-operative analgesia (may use lower opioid use with and decreases incidence of atelectasis, hypoventilation, and aspiration pneumonia)
- -Management of acute or chronic pain
3
Q
What are some advantages of using spinal anesthesia?
A
- Simple
- Predictable
- Fully conscious patient
- Analgesia into the post-op period
- Ideal for lower abdomen, pelvis/ perineum, and lower extremities
- Reduces risk of DVT*
- Use small dose of LA, less toxicity
4
Q
What are some disadvantages of Spinal Anesthesia?
A
---Sympathetic blockade 100% of the time (B fiber causes this) Hypotension --Intense motor blockade May last for hours post-op --Surgeons complain “It takes to long”
5
Q
What are the Absolute contraindications?***
A
—Patient refusal (if you do this, it is assault and battery)
—Severe psychiatric disease
May not cooperate
—Cardiovascular disease
Severe aortic/mitral stenosis and septal hypertrophy
—Severe hypovolemia
Can be corrected before the spinal
—CNS disease
MS or nerve injury
Herpetic infections
Increased ICP- brain herniation
—Blood clotting anomalies
Anticoagulant therapy
ASRA guidelines
—-Infection at the site
Septicemia or bacteremia
—Allergy to LA
Ester LA
Reaction to the preservatives
6
Q
What are the Relative contraindications?**
A
---HIV Associated with neurological manifestations ---Surgery of unknown duration ----Untreated chronic HTN Unstable BP after spinal Greater drop in BP than normal pt ---Procedures above the abdomen ---Obesity ----Deformities of the spinal column (depends what kind of deformities) ----Chronic HA or backache ----Bloody tap ----Multiple attempts ----Minor abnormalities in blood clotting ASA therapy Small dose of heparin Check coags before spinal insertion and document Platelet count
7
Q
What are the pros and cons for doing a neuroaxial block on the sick elderly patient??***
A
—PROs
Possibility of less post-operative delirium
—-CONs
Hypotension, bradycardia
Rebound HTN, tachycardia = Fluid & pressors
8
Q
What are some things to watch out for in the obstetric patient and neuroaxial block??***
A
Decreased M&M
Less effects on mother and fetus
9
Q
When doing a neuroaxial block, make sure the patient understands and accepts risk, what is the most important thing that must be documented??**
A
Document the informed consent*
10
Q
How many Cervical vertebral are there?
A
7 cervical
11
Q
How many Thoracic vertebral are there?
A
12 thoracic
12
Q
How many Lumbar vertebral are there?
A
5 lumbar
13
Q
How many Scaral vertebra are there?
A
5 sacral (fused) vertebra
14
Q
What are the vertebral bodies connect by?
A
The vertebral bodies are connected by the intervertebral disks
15
Q
The spinal column forms what shape??***
A
Spinal column forms a DOUBLE C**
16
Q
Ligamentous elements provide structural support, long with muscles help maintain shape. Ventrally (Motor) how is the spinal column supported?
A
Ventrally –Motor
Vertebral bodies and intervertebral disks are connected + supported by anterior and posterior longitudinal ligaments
17
Q
Ligamentous elements provide structural support, long with muscles help maintain shape. Dorsally (Sensory) how is the spinal column supported?
A
Ligamentum flavum = LF
Interspinous ligament = ISL
Supraspinous ligament = SSL
18
Q
What space is in between the ligamentum flavum and dura mater?***
A
Epidural space (potential)
19
Q
What space is in between the Dura mater and the Arachnoid mater?***
A
Spinal subdural space (potential)
20
Q
What space is in between the Arachnoid mater and the Pia mater?***
A
CSF (subarachonoid space)
21
Q
What covers the spinal column?
A
The meninges
22
Q
Where does the spinal cord extend too?
A
Extends from foramen magnum to L1 in adults
L3 in children
23
Q
Anterior & posterior nerve roots at each spinal level join one another and exit where?
A
Anterior & posterior nerve roots at each spinal level join one another and exit the intervertebral foramina forming spinal nerves from C1 to S5
24
Q
The single anterior spinal artery supplies how much of the spinal cord?**
A
–Single anterior spinal artery
Formed from vertebral artery at the base of the skull
–Course down the anterior surface of the cord
–Supplies the anterior 2/3 of the cord *
25
The Paired posterior spinal arteries supply how much o the spinal cord??***
- -Arise from the posterior inferior cerebellar arteries
- -Course down along the dorsal surface of the SC medial to the dorsal nerve roots
- -Supplies the posterior 1/3 of the cord *
26
Artery of Adamkiewics supplies what???***
Artery of Adamkiewics (Radicularis Magna) Blood supply to Anterior, lower 2/3 of the spinal cord- Injury due to ischemia- Anterior Spinal Artery Syndrome ***
27
What is the principal site of action for neuraxial blockade?
Principal site of action for neuraxial blockade is the nerve root
LA bathes the nerve roots in subarachnoid space or epidural space
28
Blockade of anterior nerve root fibers prevents what?
Blockade of anterior nerve root fibers prevents efferent motor and autonomic outflow
29
Blockade of neural transmission (conduction) in the posterior nerve root fibers interrupts what two things?
Blockade of neural transmission (conduction) in the posterior nerve root fibers interrupts somatic and visceral sensation
30
Sensory blockade blocks what two things?
Sensory blockade – somatic + visceral
31
Smaller and myelinated fibers are generally more easily blocked than larger unmyelinated fibers. Why?
Smaller and myelinated fibers are generally more easily blocked than larger unmyelinated fibers
- --Because the concentration of LA decreases the further away from the injection site, called the phenomenon of differential blockade
- ---Sympathetic blockade 2 segments higher than sensory blockade which is 2 segments higher than motor blockade
32
What is the Dermatome Sensory blockade rule of two mean?*****
Level of block is determine by the sensory
Sympathetic is two levels about the sensory and motor is two levels below the sensory
33
What is the oder of nerve fiber blockage??***
---B fibers-Autonomic, sympathetic efferent
---C and A Delta Temperature, Touch
--A Gamma- muscle tone
--A Beta- small motor, pressure
--A Alpha- Large Motor, Proprioception
This is the order for motor blockade
34
Due to the small size ,autonomic fibers are blocked quickly what can happen because of this?*****
In terms of Sympathectomy and BP?
- --Due to small size autonomic fibers are blocked quickly
- --Sympathectomy is accentuated in the hypovolemic pt
- --Drop in BP is the earliest sign that the spinal is working
- --A rapid drop in BP may cause nausea and dizziness
- --Treat quickly
35
Temperature and Light touch is innervated by which fibers??****
Innervated by the unmyelinated C and myelinated A-delta fibers**
Loss of these follows autonomic blockade
36
How do we assess the C and A-delta fibers?
Alcohol sponge
Loss of temperature correlates with sensory loss
37
Motor impairment and touch are innervated by which fibers??****
Myelinated A-beta & A-gamma**
---Loss of motor & touch follows loss of light touch and temperature discrimination
----Differential block
Motor block is 2 dermatones below sensory block
--Use a sharpened device or pinch method to assess level
---DO NOT USE A NEEDLE**
38
Profound Motor Block is innervated by which fibers?****
Myelinated A-alpha***
- -Motor block and loss of propioception
- --Pt’s will feel legs are still in the air after being prepped
- ---Make sure pt knows that this is normal and it will wear off
39
Where do you assess the level of profound motor block??****
```
Assess block (this is for the motor response?)
S1-2- dorsiflex his feet
L4-5- flex his toes
L2-3- raise his knees* (if they cant raise their knees, you have a L2-3 block)
T6-T12- lift shoulders off the bed (if they cant do this, you have a T6-12 block)
```
40
S2-5 is the desired level of block for what??****
S2-5***
Saddle block
No affect on the ANS
Surgical anesthesia limited to perineum, perianal, & genitalia
41
T10 is the desired level of block for what??*****
```
T10 (umbilicus)***
Low spinal
Blocks S1-5 & L1-5
Produce vasodilation, lower BP
Good for GYN, vaginal delivery, lower extremity surgery, TURP, & cysto
```
42
T4 is the desired level of block for what?****
```
T4 (nipple)***
High spinal
Used for upper abdominal surgery
Can feel traction
Can cause vasodilation and block cardioaccelator fibers
(c-section)
```
43
C8 is the desired level of block for what???***
```
C8 (little finger)***
Total spinal
Difficulty breathing
Can lead to respiratory & cardiac arrest
(should not want this)**
(you’ll have cardiac accelerators)
```
44
What are the CV manifestations of a neuraxial blockage?
CV:
↓ BP, ↓ HR, ↓ Contractility – all proportionate to the level of sympathectomy
----Vasomotor tone arises from T5-L1 – innervates arterial and venous smooth muscle
Vasodilation
Decreased venous return to heart
May decrease SVR
----REMEMBER the cardiac accelerator fibers that arise from T1-T4
45
How do you prevent the CV manifestations of a neuraxial blockage?**
```
CV effects prevention:
Loading fluid bolus 10-20ml/kg *
LUD (pregnancy)
Trendelenbug
Medications:**
ATROPINE
EPHEDRINE OR PHENYLEPHRINE
EPINEPHRINE
```
46
What are the pulmonary manifestations of a neuraxial blockade?
Pulmonary:
---Usually minimal effects
Small decrease in VC due to loss of abdominal muscle contribution
--Diaphragm innervations C3-4-5
Even with total spinal phrenic nerve may not be blocked
Apnea should resolve after resuscitation
---BEWARE in patients with limited respiratory reserve
Accessory muscles NEEDED
47
What are the GU manifestations of a neuraxial blockade?
GU:
- --Little effect on renal BF
- -Loss of control of bladder function = urinary retention with bladder distention
48
What are the GI manifestations of Neuraxial Blockade?
GI:
---Sympathetic outflow originates T5-L1
Vagal tone dominance = small contracted gut with active peristalsis
--Hepatic blood flow decreases with MAP
49
What are the metabolic and endocrine manifestations of the neuraxial blockade?
Metabolic & Endocrine:
- --Surgery causes neuroendocrine response
- Neuraxial anesthesia can partially supress or totally block responses
- Decreases catecholamine release
- May reduce perioperative arrhythmias and ischemia
50
Neuraxial Blockade and Anticoagulation
Warfarin
Oral Anticoagulants (Warfarin)
Check PT/INR
Stopped 4-5 days prior
If only one dose was given within 24 hours of block – it is safe to proceed
Epidural removal in low dose warfarin (5 mg/d)
51
Neuraxial Blockade and Antiplatelet Agents
ASA & NSAIDs***
Antiplatelet Drugs ***
ASA & NSAIDS – do not increase risk of spinal hematoma
Ticlid = 14 day, Plavix = 7 days, Rheopro = 48 hours, Integrilin 8 hours
52
Neuraxial Blockade and Anticoagulation
Heparin
Standard Heparin
Minidose SQ not contraindicated
If getting heparin intraop – block must be done 1 hour prior at least
Check PTT
53
Neuraxial Blockade and Anticoagulation
Lovenox
LMWH (Lovenox)
Concern with epidural removal (1 hour prior to med or 10 hours after )
INR is <1.5
54
Neuraxial Blockade and Anticoagulation & Antiplatelet Agents
Fibrinolytic/Thrombolytic Therapy
Fibrinolytic/Thrombolytic Therapy
| Avoid neuraxial anesthesia
55
Neuraxial Blockade and Anticoagulation & Antiplatelet Agents
Herbal Medication**
Herbal Medication
Feverfew, garlic, ginkgo or ginseng, glucosamine***** and chondroitin****** (similar to aspirin, see these last two in the elder generation)
No single evidence
One report of subarachnoid hemorrhage patient taking ginkgo
56
Surface Anatomy
Spinous processes usually palpable
Spinous processes usually palpable
Help define midline
57
Surface Anatomy
Cervical and Lumbar spinous processes******
Cervical and Lumbar spinous processes are horizontal
- --Slight cephalad angle
- --C2 first palpable, C7 most prominent
- ---Tuffier’s line L4-5 interspace (highest points of both iliac crests)
- ---S2 - Posterior superior iliac spine
58
Surface Anatomy
Thoracic spinous processes
Thoracic spinous processes slant in caudal direction
- More cephalad angle
- -T7 at level inferior angle of scapula
59
What is Tuffier’s line?????****
Tuffier’s line L4-5 interspace (highest points of both iliac crests)***
60
What are the three positions you can have for a spinal block?
-----Sitting
Easiest to visualize midline
“Mad cat”, or Shrimp position
-----Lateral Decubitus
Pt on side with knees flexed and pulled high against abdomen and chest
“Fetal position”
----Prone
Good for anorectal procedures – hypobaric
CSF does not flow freely, need to aspirate
61
What are the layers you will hit if you do a midline approach??****
Layers you will penetrate with needle:
- Skin
- Subcutaneous fat
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Dura mater
- Subdural space
- Arachnoid mater
- Subarachnoid space- CSF
62
During a spinal block, if you hit bone-->
If you hit bone:
- -superficially you are hitting lower spinous process
- --Deeper you are hitting the upper spinous process
- -Lateral you are hitting the lamina
63
How do you do a paramedian approach for a spinal??
Directed and advanced at a 10-25 degree angle toward the midline
- -Avoid most of ligaments
- -LF and epidural space entrance less subtle
Selected if patient has positioning difficulties or block is difficult
64
What is a spinal headache?
Spinal headache, the larger the lumen is the more likely you will get this, this will cause the leak of csf and essentially herniate
65
What layers will you hit if you use a paramedian approach on a spinal block?***
Layers you will penetrate with needle:
- Skin
- Subcutaneous fat
- Paraspinous muscle
- Ligamentum flavum
- Dura mater
- Subdural space
- Arachnoid mater
- Subarachnoid space- CSF
66
What layers are you missing when you go from a median to paramedian approach?***
Supraspinous ligament
| Interspinous ligament
67
On a paramedian spinal block, if you hit bone--->
If you hit bone:
- --Shallow depth you in contact with the medial part of the lower lamina, redirect upward and slightly more lateral
- -Deep depth you are in contact with lateral part of the lower lamina and should be redirected only slightly upward and more toward the midline
68
How do we test level of blockage with sensory and sympathectomy?
Testing:
Sensory ---- pinprick with blunted needle
Sympathectomy ---- temperature sensation
69
Which spinal needle is considered a sharp cutting needle?****
Quincke***
Risk for spinal headache
70
Which two needles are considered blunt spinal needles?
Whitacre and Sprotte
71
Which spinal needles will create a flap when you pull the needle out?
the Whitarce and Sprotte needle
72
What are the needle size of quincke, whitarce, and sprotte?
16-30 gauge
73
Will you see a Spinal catheter?
No, they are no longer approved by the FDA
74
Withdrawal of a spinal catheter was associated with what kind of syndrome?
Withdrawal of these catheters was prompted by their association with cauda equina syndrome
75
Is it spinal or epidural catheters that have a high complication rate?
Epidural catheters high complication rates
76
Spinal needles that are 25-26 gauge are smaller gauge to allow (blank) CSF leak, it is difficult to insert, aspirate CSF, and inject medication
Smaller gauge allows LESS CSF leak, difficult to insert, aspirate CSF, & inject medication (25-26 gauge)
77
20-22 gauge needles for spinal are larger which improves what and is a higher risk for what?
Larger gauge improves tactile feel, higher risk of PDPH (20-22 gauge)
78
For a spinal, which gauge will most clinicians use through an introducer?
Most clinicians will use the 25-26 gauge needle placed through an introducer
79
Between tetracaine and bupivicaine, which has a more profound motor block?
Tetracaine
2ml ampule of 1% (10mg/ml)
Provides a more profound motor block
80
What is the concentration of Tetraccaine for a spinal?
Tetracaine
2ml ampule of 1% (10mg/ml)
Provides a more profound motor block
81
What is the concentration of Bupivicaine for a spinal?
Bupivicaine
| 2ml ampule of 0.75% (7.5mg/ml) with 8.25% dextrose- packaged hyperbaric
82
What is the onset of Bupivicaine?
Onset of 3-5 minutes
83
Bupivicaine blocks more of what in comparing it to tetracaine?
- --Less motor block than tetracaine
| - --Blocks sensory nerves that modulate tourniquet pain better than tetracaine
84
What LA are the only drugs used for a spinal?
tetracaine, bupivicaine, lidocaine, and procaine
85
What is the concentration for lidocaine for a spinal?***
Lidocaine
2ml ampule of 5% (50mg/ml) solution premixed with 7.5% dextrose- hyperbaric
Risk of “Cauda equina syndrome” with this mixture**
86
What is the concentration for Procaine for a spinal?
Procaine
2ml ampule of 10% (100mg/ml) solution
Short duration, low potency
Solutions of greater than 5% concentration are linked to neurotoxicity
87
Intrathecal opioids will not produce surgical (blank)
Will not produce surgical analgesia
88
Intrathecal opioids will provide better anesthesia when combined with what other drug?
Does provide better anesthesia when combined with LA
89
Adding Fentanyl to LA for a spinal.. what is the dose, onset, and duration?
Dose- 15-25 mcg
Higher doses produce respiratory depression, itching, and urinary retention
Onset 5-10 minutes
Duration 2-4 hours
90
What is important side effect you will get when you add fentanyl to a spinal?
Itching
91
Adding morphine to a spinal, when will this peak? what do you have to watch out for?
Morphine will peak in 8 hours for a spinal and you will have to watch out for respiratory depression when it peaks
92
How long will morphine in a spinal provide profound analgesia for?
Provide profound analgesia for 18-27 hours
93
What type of Morphine do you need to use for a spinal, what is the onset and dose?
Morphine (preservative-free)**
Most commonly used
Onset of 60-90 minutes
Dose 0.1-0.5mg (usually 0.3mg given)
94
What is the dose for meperidine if used for a spinal?
Meperidine
| Preservative free 5-50mg of 5% solution
95
What are the two pops you feel during a spinal?
2 pops felt – LF then the dura-arachnoid membrane
96
What is a hyperbaric solution?
Hyperbaric = denser (heavier) than CSF
Glucose additive
Spreads cephalad, unless head up then spreads caudad
97
What is a hypobaric solution?
Hypobaric = less dense (lighter) than CSF
Water additive
Spreads caudad, unless head up then spreads cephalad
98
What is a Isobaric solution?
Isobaric = remain at level of injection site
99
What is Baracity?
It is the density of the LA at a specific temperature divided by the density of the CSF at the same temperature
100
What is the density of CSF?******
Density of CSF 1.004-1.008*******
101
What determines where the LA will be distributed for a spinal?
Baracity
102
What can you use to make a solution hyperbaric?
Dextrose is used to make solution hyperbaric
103
Sitting the pt after injection of LA for (how many minutes?) after injection confines the LA to the lower lumbar and sacral roots saddle block
Sitting the pt after injection of LA for "3-5 minutes" after injection confines the LA to the lower lumbar and sacral roots (saddle block)
104
With a Hyperbaric solution, what position allows the LA to move cephalad to bathe the upper lumbar and thoracic nerve roots
Allows us to inject at the lumbar area then place pt in slight trendelenburg position and allow the LA to move cephalad to bathe the upper lumbar and thoracic nerve roots
105
What is the density of a Hyperbaric solution?
Solution that has a density greater than the CSF (>1.008)
106
What is the density of a Hypobaric solution?
Solution that has a density less than the CSF where injected (<1.008)
107
How can you make a solution Hypobaric?
Diluted with preservative free sterile water
108
What is the rule of thumb for dosing for spinal?
For a T4 level: Give 1 cc for 1st 5 feet and .1cc for every 2 inches.*****
For T10= 70%
For S2/5= 40%
109
Example you have a 5’6 pt. What spinal dose will you give for a T4, T10,S2 ?
Theoretical answer 1.3cc/.9cc/.5cc
110
What are other Factors that Affect a Level of Blockade in a spinal?
---Position of patient during & after injection hypo/hyper
---Dosage of drug
--Level of injection
---Patient’s height This determines how much volume you give
---Vertebral column anatomy
----Direction of needle bevel
----CSF volume
Decreased = higher blocks (pregnant, elderly, tumors)
111
What are the spinal anesthetic agents used?
```
---Preservative free LA ONLY
Procaine, bupi, tetra,
No lido, no Ropi
----Vasopressors – limit uptake - PROLONG
Epinephrine – 0.1-0.2mg
Phenylephrine – 1-2 mcg
----Opioids
```
112
Spinal tetracaine is a better motor blockade in comparison to which Spinal LA?
Spinal tetracaine better motor blockade in comparison to bupivacaine
113
What two conditions are we concerned with, when we use lidocaine for spinal?
Cauda Equina Syndrome and Transient neurotoxicity
114
What is Cauda Equina Syndrome?**
Nerve damage to the cauda equina.
---There is a specific pattern:
Severe pain in radicular (nerve root) pattern: back, buttocks, perineum(saddle area), genitalia, thighs, legs.
--Loss of sensation: often tingling or numbness in the saddle area.
--Weakness: in legs, often asymmetric
--Bladder/bowel/sexual dysfunction: incontinence** / retention of urine; incontinence of feces; impotence/loss of ejaculation or orgasm
--Loss of reflexes: knee/ankle reflexes may be diminished, as may anal and bulbocavernosus. (a muscle of the perineum, the area between the anus and the genitals)
115
What is Transient neurotoxicity?
- ---Transient neurotoxicity of concentrated local anesthetics has been thought to be the main reason for transient neurological symptoms
- --Profound musculoligamental relaxation by high doses of local anesthetics may contribute to the development of postoperative musculoskeletal pain
- --Loss of strength of the supportive structures of the spine
116
What is the Epidural space?
- ---Is a potential space outside the dural sac
- ---Continuous from the base of cranium to the base of the sacrum
- ---Contains epidural veins, fat lymphatics, segmental arteries and nerve roots
- --Nerve roots travel in this space as they exit laterally through the foramen
117
What three ligament structures act as landmarks that help identify and access to the epidural & subarachnoid space?
Supraspinous ligament
Interspinous ligament
Ligamentum Flavum
118
What are some facts about Epidural Anesthesia?
- ---Motor block can range from none to complete
- ---Variables controlled by the choice of medication, concentration, dosage, and level of injection
- ---Slower in onset (10-20 minutes) and usually not as dense as spinal anesthesia
- ---May be manifested as a more pronounced differential block or a segmental block
119
What is the most common abnormal curvature of the spine?
Scoliosis
120
What are three abnormal curvature of the spine?
Scoliosis
Kyphosis
Lordosis
121
How does the epidrual space surround the dura mater? (in terms of position)
Epidural space surrounds the dura mater posteriorly, laterally, and anteriorly
122
What is the most commonly used needle for an epidural and what is the significance of this needle?
Standard epidural needle is typically 17-18°, 3 or 3.5” long, and has a blunt bevel with a gentle curve of 15-30° at the tip
Tuohy needle most commonly used
The blunt, curved tip helps push away the dura after passing through the ligamentum flavum
123
What is the test dose for an epidural?
- --3 mL of rapid acting low toxicity local anesthetic with epi
- --Lidocaine 1.5 % with 1: 200,00 epi
- --45 mg Lidocaine with 15 mcq of epi in 3 mL
124
What are the symptoms of an intravascular injection if you are doing an epidural?
- -Tinnitus
- -Metallic taste
- -Circumorally numbness
- -Rushing sound in ear
- -Anything different-let provider know
125
What is the rule of thumb for dosing an epidural?
Rule of thumb: 1.0-2.0 ml of LA per segment of block desired. Administer 3-5 ml of LA every 3 minutes until desired level is achieved
If initial test dose used, catheter aspirated prior to each injection, and incremental dosing used, significant systemic toxicity and inadvertent intrathecal injections are rare!
126
What is the avg distance from skin to epidural space?***
***Average Distance from skin to epidural Space- Avg. adult 4-6cm
127
How do you dose an epidural drug? (in terms of ccs)?***
*** Adults 1-2ml per segment to be blocked. With age and height decrease dosage 1ml per segment i.e.-Achieve T4 sensory block from L4-5 (12-24ml)
128
If you are doing a surgery that involves Hemorrihoids, what Sensory level do you want?
S2-S5
129
If you are doing a surgery that involves foot or knee, what Sensory level do you want?
L2-L3
130
If you are doing a surgery that involves the lower extermity, what Sensory level do you want?
L1
131
If you are doing a surgery that involves hip or TURP, what Sensory level do you want?
T10
132
If you are doing a surgery that involves a Cesarean Section, what Sensory level do you want?
T4
133
If you are doing an appendectomy, what Sensory level do you want?
T6-T7
134
What are some factors that affect the level of block for an epidural?
---Not be as predictable as with spinal anesthesia
---Dose requirements of epidural anesthesia decreases with age
----Patient height affects the extent of cephalad spread
Shorter patients may require only 1 ml of LA per segment to be blocked
Taller patients generally require 2 ml per segment
---Spread of epidural LAs tends to be partially affected by gravity
----Additives
Opioids tend to have a greater effect on quality of block
Epinephrine prolongs the effect
Sodium bicarbonate may accelerate the onset of blockade
135
What are some short and long acting agents for an epidural block?
--Short-intermediate acting agents:
1.5-2% lidocaine
3% chloroprocaine
2% mepivacaine
---Long acting agents:
0.5-0.75% bupivacaine
0.5-1% ropivacaine
136
For an epidural block, which LA has more motor block?
Lidocaine
Bupivacaine
Ropivacaine
Lidocaine
137
For an epidural block, which LA has more of a sensory block?
Lidocaine
Bupivacaine
Ropivacaine
Bupivacaine
| Ropivacaine
138
How do you treat hypotension that occurs with an epidural?
```
How to treat hypotension?
---Try to prevent it
Preload
Prophylactic administration of 1-2L of crystalloid
----Supplementary O2
---In pt’s with essential HTN
Treat drops in BP aggressively
----Treatment
Slight head down position- Trendelenburg
Bolus of crystalloid
Ephedrine 5-10mg IV
```
