NA 1 > Regional Anesthesia > Flashcards

Regional Anesthesia Flashcards

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1
Q
A

If patient doesn’t want it - severe coagulopathy is the answer

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2
Q
A
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3
Q

What is spinal anesthesia?

A

regional anesthetic technique where local anesthetic is injected into the subarachnoid space to produce temporary loss of sensation and motor function by blocking nerve transmission primarily at spinal nerve roots

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4
Q

What is epidural anesthesia?

A

regional anesthetic technique in which local anesthetic is injected into the epidural space to produce temporary sensory and/or motor blockade by diffusing through the dura to act on the spinal nerve roots.

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5
Q

Spinal versus epidural:

A

Spinals provide total sensorimotor block

Epidurals may produce segmental block
Epidurals titrated to deliver analgesia/sthesia

Epidurals allow control over extent of sensory or motor block

Epidural utilize catheter - bolus, cont. infusion, titration

Epidural has lower risk of PDPH/hypotension

Epidural LA is diffusion dependent

Epidural anesthesia may be admin. anywhere along spinal column

Epidural may take longer to perform

Epidural anesthesia takes longer to achieve

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6
Q
A

KNOW

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7
Q

How many vertebrae?

A

33
7 cervical
12 thoracic
5 lumbar
5 sacral
4 fused coccygeal

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8
Q

Sacrum =

A

Triangle shaped/fused bodies between iliac crest

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9
Q

Sacral hiatus:

A

S5 - incomplete fusion of S5 (S4) lamina - covered by sacrococcygeal ligament

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10
Q

Sacral cornua =

A

bony nodules at sides of sacral hiatus –> incomplete facet joints (Landmark for caudal anesthesia)

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11
Q

When do coccyx fuse?

A

25-30 yrs old

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12
Q

Cervical and lumbar curves are:

A

Convex anteriorly

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13
Q

What influences spread of LA in subarachnoid space?

A

Curves of column, gravity, and baricity

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14
Q

If apex is C5 and L3-L5

A

Lordosis

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15
Q

If low points are T4-T7 and S2

A

Kyphosis

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16
Q

the junction of lamina and pedicles give rise to:

A

INFERIOR and SUPERIOR articular processes

Junction known as facet/ZYGApophyseal joints

Facet joints form intervetebrla foramina

Spinal nerves exit via intervetebral foramen

Common site of injury causing spinal nerve compression –> pain and muscle spasms –> facet joint injections common in pain medicine

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17
Q

Vertebral column stabilized by a series of ___ ligaments:

A

5
Ant. Post. longitudinal ligaments:
Run along anterior and posterior surfaces of vertebral bodies

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18
Q

Supraspinous ligament:

A

Strong fibrous cord connecting apices of spinous processes form sacrum to C7

FIRST THAT THE NEEDLE WILL TOUCH

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19
Q

Interspinous ligament:

A

Thin, membranous ligament that connects the spinous processes

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20
Q

ligamentum flavum:

A

Yellow ligament/ yellow elastin fibers
80% elastin

Connects lamina together

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21
Q

Range of spinal cord:

A

Continuous above with medulla oblongata and extends to lumbar region

Birth L3
Adults extends to L1-L2 **

IMPORTANT BECAUSE Spinals placed below L2 to avoid trauma to spinal cord

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22
Q

What is the cauda equina?

A

bundle of nerve roots in subarachnoid space distal to conus medullaris

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23
Q

Filum terminale:

A

Fibrous extension of spinal cord, extends caudally to the coccyx

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24
Q

Spinal cord tapers and ends as the ____ at the level of ____ intervertebral disc

A

CONUS medullaris

L1j-L2

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25
Nerve pairs:
31 8 cervical 12 thoracic 5 5 1
26
Nerves 1-7 numbered according to what?
according to vertebral body below
27
What are the target sites for neuraxial anesthesia?
Spinal nerve roots and spinal cord
28
Membranes Dura, arachnoid and PIa divide vertebral cana into three distinct compartments:
Epidural Subdural Subarachnoid
29
Dura mater extension and info:
Outer most connective tissue layer Tough fibrous inelastic sheath that extends form cranial vault to sacrum (S2) Laterally teh dura mater covers each spinal nerve
30
Arachnoid mater:
Cobweb mother Thin intermediate membrane (Between pia and dura) Terminates at S2
31
Pia mater:
Soft mother Thin sheet of vascular fibroelastic tissue Inner most connective tissue layer Cord and nerves closely surrounded by pia mater Terminates as filum terminale
32
Epidural space (Extradural, peridural) surrounds what and extends?
Surrounds meninges circumferentially Extends from foramen magnum to sacral hiatus
33
Boundaries of epidural space:
Foramen magnum (Cranial) Sacrococcygeal ligament (Caudal) Post. longitudinal ligament (Anterior) Vertebral pedicles (Lateral) Ligamentum flavum/vertebral lamina (post Contains nerve roots, fat, vessels 5mm wide Potential space
34
Skin to epidural space in average patient:
5cm (2-9cm)
35
Subarachnoid (Intrathecal) space contains what?
Lies btw pia and arachnoid space Contains mumerous arachnoid trabeculae - forming delicate, sponge like mass Space contains: spinal cord, nerves, CSF, blood vessels
36
Cerebrospinal fluid characteristics, gravity, daily secretion, amount, normal pressure:
Clear colorless fluid that fills the subarachnoid space Ultra filtrate of plasma Specific gravity - 1.004 - 1.009 Daily secretion 500ml 30-80mL in spinal canal (Total about 140-150mL between spinal canal and cranium - 1/2 and 1/2 Normal pressure 10-20cm H20
37
What is the anterior spinal artery?
Branch of vertebral artery Anterior 2/3 of spinal cord
38
What is the posterior spinal artery?
Branch of posterior inferior cerebellar artery Posterior 1/3 of spinal cord
39
Spinal anesthetic midline approach layers of anatomy traversed from posterior to anterior:
Skin Subcutaneous fat Supraspinous ligament Interspinous ligament Lig. flavum Dura mater Subdural space Arachnoid mater Subarachnoid space
40
Spinal anesthetic Paramedian approach layers traversed:
Skin Subcutaneous fat Lig. falvum Dura mater Subdural space arachnoid mater subarachnoid space
41
Indications for spinal anesthesia
Operations of perineum, lower abdomen, and lower extremity High quality anesthesia Avoid ETT in patient with respiratory problems or difficult airway Decreased risk of vomiting and aspiration NOT ELIMINATED Same preoperative fasting guidelines Muscle relaxation Patient remains awake Chronic pain therapy Postoperative analgesia Labor analgesia & C-section section Optimal choice for TURP to monitor for TURP syndrome Spinal plus light general anesthesia for upper abdominal surgery Cholecystectomies and gastrectomies
42
Risk of N/V with spinals:
Decreased! but NOT eliminated Same preoperative fasting
43
What does spinal anesthesia consist of and what is the primary and secondary site of action?
Consists of injecting local anesthesia into the cerebral spinal fluid (CSF) within subarachnoid (intrathecal) space of spinal cord The local anesthetics bind to nerve tissues and disrupt nerve transmission Primary site of action for local anesthetics = nerve roots Secondary site of action = spinal cord Interrupts sensory, motor and SNS innervation
44
Differential sensitivity:
Difference in how local anesthetics affect different nerve fibers
45
Differential blockade:
Temporary blocking of nerve fibers using local anesthetics
46
Factors that affect diff. sensitivity
Fiber type - Unmyelinated fibers are more resistant to local anesthetics than myelinated fibers Fiber size - Smaller fibers are more susceptible to local anesthetics than larger fibers Local anesthetic - Some local anesthetics, like bupivacaine and ropivacaine, are more selective for sensory fibers
47
48
When the distance from the injected site increases -->
Amount of LA decreases and fewer molecules are available to produce a block of nerve transmission This and different nerve fiber sensitivites provides rationale for zones of differential blockade
49
In neuraxial anesthesia, how are sympathetic nerve fibers blocked by?
The lowest concentration of LA followed by nerve fibers responsible for pain, touch and finally motor function
50
B fibers are easiest to block because htey are on the outside in the cross section Block SNS --> Sympathectomy
51
Local anesthetic onset path:
B C/A delta A Gamma A beta A alpha
52
Local anesthetic is deposited near the nerve and requires___
Diffusion towards the nerve, away from the nerve, into the nerve, and along the axis of the nerve
53
Sequence of neural blockade (Effects)
1. loss of sympathetic fx 2. pain 3. sensation of cold, warmth, touch, deep pressure 4. proprioception 5. motor function
54
Potency is _____ and it is primarily related to _____
Dose required to achieve anesthetic effects Lipid solubility
55
Higher potency =
Longer DOA
56
Duration of action of local anesthetic is affected by:
Protein binding (also lipid solubility and regional blood flow)
57
How do we dose a spinal?
1st - level of block dictated by sx procedure 2nd - determine dermatome level to cover that level
58
Since needle inserted below spinal cord (L2-L3) -->
Position and baricity are important to manipulate height of the block.
59
What is a dermatome?
Area of skin that receives sensation (touch, pain, temp) from a single spinal nerve Territory of skin that belongs to the nerve
60
Regions with dermatome matching:
Umbilical area is dermatome T10 but anterior to L3 Damage to L5 in nlower back leads to sensations such as pain or numbness the area of your leg that belongs to L5
61
KNOW
62
T10 dermatome corresponds to:
Umbilicus
63
T6 dermatome corresponds to:
Xiphoid
64
T4 dermatome corresopnds to:
Nipples
65
Factors affecting block distribution!!
Ratio of LA density to CSF patient POSITION during and just after injection DOSE of LA injected
66
Know top line
67
Epinephrine spinal additive use:
Decrease absorption, prolong DOA, enhance sensory and motor effects, and serves as possible marker for inadvertent intravascular injection (More for epidural) 0.1-0.2mL of 1:1,000 (1mg/1mL)
68
Opioids spinal anesthesia additives:
Prolong duration and enhance analgesia Fent, morphine, sufent, meperidine Fentanyl = 10-25 mcg Morphine = 0.1-0.5mg (See DURAMORPH - up to 1 mg)
69
A2 adrenergic agonists additives to spinals:
Prolongs duration and enhances analgesia Clonidine 150mg Dexmedetomidine 5 mcg
70
What does spinal anesthesia block?
Sympathetic chain, which is the main mechanism of cardiovascular changes Sympathectomy
71
What determines the level of sympathetic bockade which determines the degree of change in cardiovascular parameters?
Nerve block hight
72
High block =
Complete sympathectomy - more severe physiologic response Leads to hypotension and complex effect on HR
73
Why does hypotension occur with spinals?
Preganglionic sympathetic blockade --> effecting preload, afterload, contractility and HR and decreasing SVR
74
WHy is preload decreased with spinals?
Sympathetic block induced venodilation (pooling of blood in periphery reduces venous return to the heart) Venous system is maximally dilated - reliant on gravity for return to heart - position and aortocaval (Gravid uterus) compression have significant effect on venous return during a sympathectomy Arterial system dilated reducing SVR but not maximally
75
Consequences of hypotension with spinals:
N/V - common, likely d/t chemical sympathectomy with unopposed PSNS tone and or hypotension - GIVE ephedrine Ischemia of critical organs CV collapse Fetal compromise
76
Management of hypotension with spinals:
USE clinical judgement Health and asymptomatic - dont treat <33% decrease in BP CV disease - Treat >20-25% decrease in BP Monitor BP, ECG (ST segment), sats, fetus Provide supplemental oxygen
77
Management of decreased preload:
FLUID - Preemptive preload technique = crystalloid 15-20ml/kg over 20 mins - Tx of hypotension first response = 500-1500mL IVF - not effective if pt normovolemic
78
Position with decreased preload:
Tren > 20 degrees may decrease CBF due to increased jugular venous pressure MAKE SURE height of spinal fixed before changing position Leg compression Uterine displacement
79
Management of vasodilation with spinals:
Vasoconstrictor Preemptively hydrate if patient is hypovolemic
80
Vasopressor drug of choice and dose:
Ephedrine - indirect action, stimulation of alpha, beta 1 and beta 2 receptors CO and PVR are increased with ephedrine thus restoring BP 5-15mg IV
81
Epinephrine Action and dose:
Direct action, more beta than alpha Do not hesitate to use in extreme bradycardia 5mcg IV
81
Phenylephrine action and dose:
Direct action, stimulation of alpha receptors 50-100mcg IV
82
Bradycardia drugs of choice:
Atropine 0.4-0.8mg/glycopyrrolate
83
Tachycardia with spinals:
Baroreceptor reflex Negative feedback loop to maintain BP Hypotension (From spinal anesthsia) decreases baroreflex activation and causes heart rate to increase to restore BP
84
Bradycardia with Spinal anesthetics:
Sympathetic block of cardiac accelerator fibers T1-T4 -slow onset -poisition changes do not increase HR Reverse bainbridge reflex Bezold-Jarisch reflex
85
High risk of bradycardia with spinals patients:
Young and health BB
86
Reverse bainbridge reflex:
Decreased HR due to decreased venous return Detected by stretch receptors in right atrium - explains why low spinal levels below cardiac accelerator fibers produces bradycardia Bradycardia CORRELATES with decreased arterial blood pressure (Decreased venous return) Trendelenburg increases HR WIth a T1-T4 block - raising the HR wont work
87
Bezold-jarish reflex:
Hypopnea, hypotension, bradycardia Sympathectomy reduces venous return to the heart > decreased BP > this is sensed by carotid baroreceptors causing rapid contraction of ventricles > rapid contraction of underfilled ventricles activates 5HT3 receptors (on LV) > resulting in hypotension, bradycardia and vasodilation due to vagal activation
88
Tx of BJR:
5HT3 antagonist (Ondansetron) 5HT3 receptors on vagus nerve and myocardium --> blocked receptors can't be activated and cause vagal response
89
Cerebrovascular autoregulator mechanism maintains cerebral blood flow at:
MAPs > 50-55mm Hg
90
Cerebrovascular autoregulation is _____ of SNS
Independent Treat hypotension to maintain cerebral blood flow
91
Spinals effect on neurologic system:
No direct depression of cortex or brainstem --> changes secondary to reduced cerebral perfusion, systemic hypotension, sedation Spinal anesthesia decreases sensory input to RAS --> Somnolence
92
Respiratory impact of spinals in normal lungs:
Minimal effect
93
High blocks into thoracic area can cause what with respiratory?
Block intercostal and abdominal muscles --> may influence ACTIVE exhalation --> ability to cough or clear secretions in patient's with pulmonary compromise Healthy patients - decreased sensation of chest and abd. movement with normal breathing may lead to sensation of dyspnea IS patient speaking and oxygenating?
94
Kidneys and liver with spinals:
Liver = no autoregulation --> heaptic blood flow correlates to arterial flow --> MAINTAIN BP Kidneys = Autoregulated - spinal doesn't alter - kidneys perfused when MAP remains above 50mmHg --> maintain BP
95
In regards to kidney and liver, if mean blood pressure is maintained -->
Neither Hepatic or renal blood flow will decrease:
96
Urethra with spinal anesthetics?
Increase tone of sphincter --> urinary retention
97
GI system with spinals:
Unopposed PSNS activity - through vagus nerve Sympathetic innervation by T5-L2 Blockade = Increased secretions, sphincters relax, bowel constricts, increased peristalsis, increased intraluminal pressure, increased blood flow N& V = GIhyperperistalsis (Nausea), hypotension (Nausea), hypoxemia, meds (Opioids or rapidly infused antibiotics - Atreopine treats nausea.
98
Paramedian (lateral) and goal:
Goal to avoid narrowed or calcified interspinous space 1cm lateral to the midline directly opposite the cephalad edge of the spinous process below the selected interspace Direction of needle is 10-20 degrees midline and slightly cephalad
99
Epidural LA MOA:
Spinal nerve roots primary site of action for LA Mixed spinal nerves in epidural, and spinal cord
100
What makes epidurals rely on to make their action?
Spinal roots are away from the site of action: Dura - acts as a barrier Absorption into circulatory system Risk of toxicity - large vous network in epidural spa e retention in fatty tissue Fat acts as a reservoir, redistributes over time
101
Epidurally administered LA site of action:
SPINAL nerve roots Rootlets Mixed spinal nerves DRG Spinal cord Brain - reaches SC and impulses not conducted to brain
102
What is the most important route of entry for epidurals?
Dural cuff region Many proliferations of arachnoid villi and granulations Grandulations effectively redue the thickness of the dura mater, permitting rapid diffusion of anesthetics from the epidural pace through the dura and into the CSF Also diffuses into paravertebral area leading to multiple paravertebral blocks Also reaches spinal cord though absorption into radicular arteries
103
Factors influencing levels of epidural: 4
Large dose = more intense sensory/motor block and duration Increased Concentration = reduces onset time and increases density/intensity of motor block Larger VOLUME = greater vertical spread Age and pregnancy
104
Level of catheter influence of epidural:
Ideal insertion is near surgical level (Midpoint) Leads to more rapid onset and intense block Lumber: greater cranial than caudal spread - delay at L5-S1 due to large size of roots Midthoracic: even spread form site of injection
105
Addition of vasoconstrictors for epidurals:
Constricts vessels, prolongs duration, and increases intensity of agent's effect
106
107
The most significant affectingspread of epidural anesthesia are:
DOSE (Concentration x volume) Site of injection
108
The baricity of local anesthetic agents ______ spread of epidural anesthesia:
Does NOT affect
109
Duration of anesthesia is influenced by:
Choice of local anesthetic Addition of vasconstrictor - Epi
110
Initial dosing:
1-2ml/segment to be blocked (Less in thoracic and cervical regions) - Biodirectional spread from injection site - Epidural at T7, want sensory block from T4-T10, this is 7 spinal segments, inject 6-12mL of local anesthetic (Consider age, height and spinal anatomy influences on spread)
110
Dose considerations pharmacology KNOW:
Aspirate before injection Inject 3-5 ml at a time every 3-5 mins Loading dose - usually hgih concentration local solutions (2% lido or 0.5 rop) Intermittent injections/bolus or continuous infusion Continuous infusion: - usually lower concentration local aneshtetic solutions (0.0625% - .125% bupivacaine)
111
Top up dose:
33.3-75% (1/3 to 2/3) of the initial dose (Given at 2 segment dermatome regression) - sources vary
112
113
114
What is a test dose and how to perform?
3cc 1.5% lido with 1:200,000 epi - 45mg lido and 15 mcg epi Assesses for IT catheter - sensory block in 3-5 min - should not give >T10
115
What does intravascular injection look like?
Cause increase in HR 15-20 bpm for 2-3 min If signs of systemic toxicity remove immediately and treat symptoms
116
HR changes MAY NOT be reliable in ____ with intravascular injection:
Elderly Beta blocked patients Pregnant women
117
What does epinephrine do?
Reduces vascular absorption Enhances intensity of motor block Quality of sensory block and duration of block
118
Using vasoconstrictors like epi is more affective in:
Short/intermediate acting LA's
119
Commercial preparations of LA with epi are very____ resulting in greater latency to onset of block
Acidic
120
Bicarb function:
Increases ph - speeds onset, increases potency, reduces pain on injection 1cc of 8.4% sodium bicarb to 9 ml of LA May precipitate with bupivacaine
121
Opioids function:
Must cross dura to opioid receptors in substantial gelatinosa Retained in fat/connective tissue Abosrbed into systeemic circulation via vasculature 10 x the dose of intrathecal
122
Morphine opioid dose:
2-5mg DepoDUR (Extended release epidural morphine) --> uses a drug release delivery system called DepoFoam DepoFoam is composed of microscopic lipid-based particles with internal vesicles that contain the active drug and slowly release it Risk of delayed respiratory depression
123
Fentanyl dose opioids
50-100mcg
124
Sufentanil dose:
10-60mg
125
Hydromorphone dose:
1 mg
126
What are the wings on epidural catheter for?
To grasp
127
What is the clear hub for epidural catheter?
Early detection of CSF or blood
128
Epidural catheters anatomy:
Multi orifice catheters Catheter tip marking Catheter - 1st 5cm is single mark, 10cm double, 15 triple mark, 1 cm markings in between
129
How may cm would like in epidural space:
3-5cm of epidural catheter into epidural space 5cm to get into spiedural space - then 5 more IN epidural space Secured at 10
130
Cervical insertion positioning and technique?
Sitting Midline
131
Throacic insertion position and technique?
Lateral or sitting Paramedian approach allows easiest access to epidural space
132
Lumbar insertion position and approach?
Lateral or sitting Midline - identify intervertebral space in the midline - slight 10 degree upward angulation
133
Two categories of complications of neuraxial blocks:
Complications from needle used Complications from medications used
134
Complications from needles being used:
PDPH Backache Maternal fever TNS
135
Compliations from medications used:
Nausea High or total spinal Cardiac arrest Systemic toxicity (LA toxicity) Urinary retention Cauda equina Meningitis/aracnoiditis Epidural abscess or hematoma Spinal or epidural hematoma
136
Cardiovascular complications of epidural:
Hypotension - sympathectomy Bradycardia - T1-T4 blockade - Reflexes
137
Treatment of bradycardia with epidural:
Atropine Brady and hypotension - Fluid and ephedrine or epi
138
Causes of N/V with epidurals:
HYPOTENSION additive drugs - opioids Inadequate block - surgical stim >T6 increased risk - over activity of PSNS Hx motion sickness Increased HR Anxiety, decreased lwoer esophageal sphincter tone, increased gastric pressure, vagal hyperactivity, uterus manipuylation, peritoneal traction, opioids, antibiotics
139
Respiratory complications with epidurals:
Rare with low spinal High spinal - paralysis of accessory muscles and ineffective cough
140
Urinary system complications:
Urinary Retention - sacral blockade (S2-4) causes an atonic bladder and retention of urine Sympathetic blockade of T5-L1 results in increased sphincter tone - Tx: Foley (600ml) - Be aware of fluid
141
PDPH MOA:
Dural puncture --> CSF leak --> cerebral vessels dilate and brainstem sags into foramen magnum --> stretches meninges and pulls on tentorium
142
Increased incidence with PDPH:
Female Pregnant Age Large non-pencil point needles or cutting wihtout horizontal bevel insertion Multiple insertions
143
S/S of PDPH:
Headache - frontal, occipital, radiate to neck, relieved when supine
144
What needle to reduce risk of headaches:
Pencil point - 25-27g widicker needle on pregnant patients
145
S/S of PDPH besides headache:
N/V Blurred vision/photophobia Appetite loss Tinnitus Vertigo Plugging of ears Depression
146
Treatment for PDPH:
Supine Fluids analgesics abd. binder Caffeine 500mg IV caffeine benzoate/300mg oral caffeine Sphenopalatine block
147
Epidural blood batch for PDPH:
Clot formation that seals dural puncture 12-15mL of autologous blood into epidural space Inject until patient senses pressure in back, buttock or legs Supine 30-60 min after headache relief instantaneous Backpain
148
Definitive treatment for PDPH:
Blood batch
149
Epidural hematoma etiology
Accumulation of blood in epidural space creating pressure on nerve roots
150
S/S of epidural hematoma:
Mild back pain and/or sensory and motor neural deficit progresses to paraplegia and incontinence - onset 12 hours to 2 days post blockade or catheter removal with epidural Prevention is Key
151
Dx of epidural hematoma:
MRI
152
Tx of epidural hematoma:
Surgical decopression in 8 hours
153
S/S of high/total spinal:
Severe hypotension Bradycardia Resp. insuffiency Later: - unconsciousness, apnea ONSET --> RAPID
154
Etiology of high/total spinal
Spread of LA along entire spinal cord and brainstem
155
Tx of high/total spinal:
Supportive Airway management - ensure arterial oxygenation and ventilation CV support - Hypotension: vasopressors and IV fluids Bradycardia: atropine Bradycardia and hypotension: ephedrine or epinephrine
156
Backage incidence:
25% patients 25-30% of patients that receive only GA complain of backache postop
157
Etiology of backache:
Localized inflammatory response andm uscle spasms from needle Traumatic puncture Excessiv einfiltration of LA in subQ tissue Usually benign but keep epidural hematoma and abscess in mind Also exacerbation of pre existing neuro, infection
158
Tx of backache
Analgesic and reassurance
159
Epidural abscess:
Rare but devastating PRESENTS as acute radicular back pain Staphylococcus aureus
160
Four stages of epidural abscess:
Back or vertebral pain that is intesnified by percussion over area Radicular pain Motor/sensory deficits or sphincter dysfunction Paraplegia or paralysis
161
Dx of epidural abscess:
Emergent MRI or CT
162
Tx of epidural abscess:
Abx and sx (Decompressive laminectomy within 6-8 hours to prevent neurologic sequala)
163
TNS symptoms:
Pain originating in gluteal region which radiates to both lower extremities Burning, aching, cramping, radiating in anterior and posterior thigs Symptoms appear within a few hours to 24 hours after recovery from neuraxial block
164
Tx of TNS:
Usually sponteneoulsy resolves Lidocaine implicated COnsider other causes: position Supportive --> NSAIDs
165
Cauda Equina syndrome:
Persistent paralysis of nerves of cauda equina with LE weakness and bowel and bladder dysfunction
166
Cause of cauda equina syndrome:
Lidocaine 5% (high concentration hyperbaric) implicated
167
Know max doses
168
169
LAST Etiology:
Due to inadvertent vascular injection or absorption of large amounts of drug (High volume blocks or continuous infusions
170
Large amounts of local anesthetic depresses what?
Sodium Potassium Calcium channels in excitable tissues of CNS and CV systems CNS -> Inhibitory neurons blocked first --> seizures CV --> initially HTN and tachyarrhythmias progressing to depressed cardiac conduction, performance, reduced CO, Bradycardia and hypotension
171
Highest risk with LAST?
Bupivacaine
172
Early signs of LAST:
Lightheadedness Tinnitus Agitation Circumoral/tongue numbness Metallic taste visual disturbances
173
Late signs of LAST:
Muscular twitching Convusions Unconsciousness Coma Resp arrest CVS depression
174
Pathway with LAST:
INhibitory pathways in brain first --> leaving unopposed excitation (disinhibition) --> as lbood levels increase --> more resistance excitatory pathways are inhibited --> unconsciousness and coma
175
LAST prevention:
Double check dose, test dose, aspirate prior to injection and every 5 c's Consider pharmacologic marker --> epi - EPi as vascular markers (5-15mcg) - Positive signs are increased HR --> 10bpm or increase in systolic bp more than 15 mmHg Verbal communcation
176
Tx of LAST:
Airway management - ventilate with 100% - Prevent hypoxia and acidosis Seizure suppression - Benzo preferred because less CV effects BLS and ACLS intralipids
177
Tx of LAST main:
Lipid EMULSION (<70kg) -Bolus intralipid 20% 1.5ml/kg over 2-3 minute IBW -Infusion of intralipid at 0.2-0.5 ml/kg/min IBW -Repeat bolus up to 3 times -Continue infusion 10 minutes -Recommended upper limit: 12ml/kg over 30 mins -Over 70kg > IV bolus 100ml over 2 min -Continuous IV infusino 200-250ml over 20-30 min
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What to avoid with LAST?
Vasopressin CCB BB LA Propofol with CV instability Small doses of epi with ACLS (<1mcg/kg)
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Anticoagulation summary
Aspirin or NSAID= neuraxial blocks safe COX-2 inhibitors=neuraxial blocks safe Clopidogrel (Plavix)= discontinue 5-7 days before Ticlopidine (Ticlid)= discontinue 10-14 days before Dabigatran (Pradaxa) = discontinue 5 days before Warfarin (coumadin) = discontinue 4-6 (5) days & “normal” INR<1.4 IV Heparin= hold 4-6 hours before block & “normal” coagulation, wait >1 hr after block before administering Hold 4-6 hours & “normal” coagulation prior to removing catheter Restart medication 1-hour after catheter removal Low dose SC = discontinue 4-6 hours before Intermediate dose SC = discontinue 12 hours before High dose SC = discontinue 24 hours before Low dose LMWH (Lovenox)=discontinue 12 hours before Higher dose LMWH (1 mg/kg q 12 hr or 1.5 mg/kg daily)= wait 24 hours
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Preop assessment and patient prepartion for procedure:
IDENTIFY and document cognitive, sensory, motor and coordination deficits
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Aseptic technique:
-No current consensus regarding infection control -ChloraPrep (chlorohexidine and isopropyl alcohol) common 0.5-2% -Full barrier technique recommended when placing an indwelling catheter -Vigilance and follow-up of site of regional anesthesia important -Catheter site covered with transparent dressing to allow inspection -Chlorhexidine associated with decreased risk of central venous catheter–associated bloodstream infections compared with povidone iodine
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Midline approach:
Midline Lower third of interspace Slight cephalad direction (10 degrees)
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Just beyond ligamentum flavum -->
Feel a pop and advance through dura Remove stylet and watch for free flow of CSF (May rotate needle to confirm placement
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Tuohy needle:
Pronounced curvature 30 degrees
NA 1
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