3722183.ppt

NEURAXIAL
ANESTHESIA:
SPINAL
EPIDURAL
CAUDAL
Rebecca Johnson, CA3 November 29, 2012

Outline
 Anatomy
 Mechanism of Action
 Systemic Manifestations
 Indications/Contrandications
 Anticoagulants/Antiplatelets
 Anatomic Approaches
 Spinal Anesthesia
 Epidural Anesthesia
 Caudal Anesthesia
 Complications

All of the following are true EXCEPT:
 A. The interspinous ligament attaches to the ligamentum flavum.
 B. The ligamentum nuchae continues inferiorly as the supraspinous
ligament.
 C. The ligamentum flavum is thickest in the midline and elastin is the
primary component.
 D. The epidural space terminates cranially at C1.
 E. The epidural space is bounded inferiorly by the sacrococcygeal ligament.

Answer:
 Boundaries of Epidural Space:
 Posterior:
 ligamentum flavum/vertebral laminae
 Anterior:
 posterior longitudinal ligament
 Lateral:
 vertebral pedicles/intervertebral foramina
 Inferior:
 sacrococcygeal ligament covering sacral hiatus
 Superior:
 foramen magnum
 D.

Vertebral Column
 7 cervical vertebrae
 12 thoracic vertebrae
 5 lumbar vertebrae
 5 fused sacral vertebrae
 Rudimentary coccygeal vertebrae
 Paired spinal nerves exit at each level, C1 to S5
 At cervical level
 nerves arise above respective vertebrae
 Starting at T1
 nerves exit below their vertebrae
 As a result…
 8 cervical nerve roots but only 7 cervical
vertebrae

Spinal Canal
 Contains:
 Spinal cord
 Meninges (3 layers)
 Pia Mater
 Arachnoid Mater
 Dura Mater
 Fatty tissue
 Venous plexus
 CSF
 Subdural space
 Poorly demarcated, potential space that exists between the
dura and arachnoid membranes

Anatomic features pertinent to the performance of
neuraxial blockade include all EXCEPT:
 A. In adults, the spinal cord ends at L1-L2.
 B. The angulation of the spinous process of the thoracic
vertebrae makes a paramedian approach preferable.
 C. In adults the dural sac ends at S2.
 D. The largest interspace in the vertebral column is L4-L5.
 E. Midline insertion of an epidural needle is least likely to
result in unintended meningeal puncture.

Answer
 D.
 The largest interspace is L5-S1.
 The ligamentum flavum is farthest from the spinal
meninges in the midline, measuring 4-6mm at L2-
L3 interspace.

Anatomy
 The spinal cord extends from the
foramen magnum to the level of L1 in
adults
 In infants, the spinal cord ends at L3
and moves up as they grow older
 Lower nerve roots course some
distance before exiting the
intervertebral foramina
 Forms the cauda equina
 Pushing vs piercing the cord
 The dural sac, subarachnoid and
subdural spaces usually extend to S2 in
adults
 Often to S3 in children

Blood Supply
 Anterior 2/3 of cord
 Anterior spinal artery
 vertebral artery
 Posterior 1/3 of cord
 Two posterior spinal arteries
 posterior inferior cerebellar arteries
 Radicular arteries
 intercostal arteries in the thorax
 lumbar arteries in the abdomen
 The artery of Adamkiewicz
 Aorta
 Typically unilateral and on the ___ side?
 Left
 Major blood supply to the anterior, lower 2/3 of the spinal cord
 Injury to this artery can result in …?
 Anterior spinal artery syndrome

Mechanism of Action
 Principal site of action - nerve root
 Local anesthetic bathes the nerve root in the
subarachnoid space or epidural space
 Spinal anesthesia:
 Direct injection of LA into CSF
 Relatively small dose and volume to achieve
dense sensory and motor blockade
 Epidural/Caudal anesthesia:
 Same LA concentration is achieved at nerve roots only with much
higher volumes and quantities
 Level for epidural anesthesia
 Must be close to the nerve roots that are to be anesthetized

Somatic Blockade
 Sensory blockade interrupts both
somatic and visceral painful stimuli
 Motor blockade produces skeletal
muscle relaxation
 Provides excellent OR conditions
 LA effect on nerve fibers varies
according to many factors:
 Size of the nerve fiber
 Myelination
 Concentration achieved
 Duration of contact
 Smaller and myelinated fibers are
more easily blocked

Somatic Blockade
 Spinal nerve roots contain varying mixtures of these fiber types and
they vary in their sensitivity to the LA blockade
 This results in a differential block
 Which nerve fibers are blocked by the lowest sensitivity to LA?
 A. pain
 B. motor
 C. sympathetic
 D. touch
 Order of sensitivity:
 Sympathetic > pain > touch > motor

Somatic Blockade
 Sympathetic block is highest,
generally 2 (up to 6) segments
higher than the sensory block
(pain, light touch)
 Which in turn is usually 2-3
segments higher than the
motor blockade

Autonomic Blockade
 Block of efferent autonomic transmission
 sympathetic and some parasympathetic blockade
 Sympathetic outflow from the spinal cord
 Thoracolumbar
 Sympathetic preganglionic nerve fibers
 exit the spinal cord with the spinal nerves from T1 to the L2 level and
 may course many levels along sympathetic chain before synapsing with a
postganglionic cell in a sympathetic ganglia
 Parasympathetic outflow
 Craniosacral
 Parasympathetic preganglionic fibers exit the spinal cord with the
cranial and sacral nerves
 Neuraxial anesthesia does not block the vagus nerve
 decreased sympathetic tone and/or unopposed parasympathetic tone

A pt receives a spinal anesthetic with a sensory level
of T5. Which of the following is likely to occur?
 A. The small bowel will be dilated and relaxed.
 B. Glomerular filtration will be decreased by one
third.
 C. Tidal volume will be reduced by one third.
 D. The cardioaccelerator nerves will be unaffected.
 E. Blood pressure will lower predominantly by
decreasing venous return.

Answer
 E
 Level of sympathetic block can be 2-6 levels
higher than sensory block.

Cardiovascular Manifestations
 Variable decreases in blood pressure
 +/- decrease in heart rate and cardiac contractility
 Generally proportional to degree of the sympathectomy
 Arterial and venous smooth muscle vasomotor tone:
 Innervated by sympathetic fibers from T5 to L1
 Blocking these nerves causes:
 vasodilation of the venous capacitance vessels
 pooling of blood
 decreased venous return to the heart
 Arterial vasodilation may also decrease SVR
 May be minimized by compensatory vasoconstriction above the
level of the block

 A high sympathetic block
 prevents compensatory vasoconstriction
 blocks the sympathetic cardiac accelerator fibers
that arise at …?
 T1–T4
 Profound hypotension may occur
 Vasodilation combined with bradycardia and decreased
contractility
 Exaggerated if venous return is further compromised
 head-up position or gravid uterus
 Sudden cardiac arrest sometimes seen with spinal anesthesia
 Unopposed vagal tone

 Steps to minimize the degree of hypotension:
 Volume loading with 10–20 mL/kg of IVF
 partially compensates for the venous pooling
 LUD in the third trimester of pregnancy
 minimizes obstruction to venous return
 Hypotension may still occur
 Increase IVFs
 Autotransfusion - head-down position
 Vasopressors (phenylephrine/ephedrine)
 Excessive or symptomatic bradycardia
 Atropine
 If profound hypotension and/or bradycardia persist
 Epinephrine (5–10 mcg)

Pulmonary Manifestations
 Usually are minimal
 diaphragm innervated by the phrenic nerve
with fibers originating from C3–C5
 Even with high thoracic levels…
 tidal volume is unchanged
 only a small decrease in vital capacity
 from loss of abdominal muscles' contribution to forced expiration
 Phrenic nerve block may not occur even with total spinal
anesthesia
 apnea often resolves with hemodynamic resuscitation
 suggests that brain stem hypoperfusion is responsible

 Severe chronic lung disease patients
 Rely upon accessory muscles of respiration
 Coughing and clearing of secretions require these muscles
 High levels of neural blockade impair these muscles
 Use caution in patients with limited respiratory reserve
 Must weigh against the advantages of avoiding airway
instrumentation and PPV
 Surgery above the umbilicus
 Pure regional technique may not be
the best choice

 Thoracic or upper abdominal surgery
 Decreased diaphragmatic function postop
 Decreased FRC
 Atelectasis and hypoxia via V/P mismatch
 Postop thoracic epidural analgesia may improve
pulmonary outcome
 decrease the incidence of
pneumonia and respiratory failure
 improve oxygenation
 decrease duration of vent
support

GI Manifestations
 Sympathetic outflow originates at T5–L1
 Sympathectomy - vagal tone dominance
 small, contracted gut with active peristalsis
 Excellent operative conditions for lap procedures when
used as an adjunct to GENA
 Postoperative epidural analgesia has been shown to hasten
return of GI function
 Hepatic blood flow will decrease with reductions
in MAP from any anesthetic technique
 Intraabdominal surgery - decrease in hepatic
perfusion related more to surgical manipulation
than to anesthetic technique.

Urinary Tract Manifestations
 Renal blood flow – maintained through autoregulation
 little clinical effect upon renal function
 Neuraxial anesthesia at the lumbar and sacral levels blocks both
sympathetic and parasympathetic control of bladder function
 Loss of autonomic bladder control results in urinary
retention until the block wears off
 If no urinary catheter is anticipated perioperatively:
 use the shortest acting and smallest amount of
LA necessary for the procedure
 limit the amount of IVF as much as possible
 Monitored pt for urinary retention to avoid
bladder distention following neuraxial anesthesia

Metabolic & Endocrine Manifestations
 Surgical trauma produces a neuroendocrine response
 localized inflammatory response
 activation of somatic and visceral afferent nerve fibers
 increases in ACTH, cortisol, epinephrine, NE, and vasopressin
 activation of the renin–angiotensin–aldosterone system
 Clinical manifestations:
 HTN, tachycardia, hyperglycemia, protein catabolism, suppressed immune
responses, and altered renal function
 Neuraxial blockade can partially suppress (during major invasive
surgery) or totally block (during lower extremity surgery) this stress
response
 Reduction in catecholamine release
 may decrease perioperative arrhythmias and reduce the incidence of
ischemia
 Neuraxial block should precede incision and extend postop

Indications for Neuraxial
 Used alone or in conjunction with GENA for most
procedures below the neck
 Most useful for:
 lower abdominal
 inguinal
 urogenital
 rectal
 lower extremity surgery
 Lumbar spinal surgery may also be performed
under spinal anesthesia
 Upper abdominal procedures
 difficult to achieve a sensory level adequate for patient comfort yet avoid the
complications of a high block
 Spinal anesthesia for neonatal surgery

Contrandications
 Patient refusal
 Infection at the site of
injection
 Coagulopathy or other
bleeding diathesis
 Severe hypovolemia
 Increased intracranial
pressure
 Severe aortic stenosis
 Severe mitral stenosis
 Preexisting
neurological deficits
 Sepsis
 Uncooperative patient
 Demyelinating lesions
 Stenotic valvular heart
lesions
 Severe spinal
deformity
Absolute Relative Controversial
 Inability to
communicate with pt
 Prior back surgery at
site of injection
 Complicated surgery
 Prolonged operation
 Major blood loss
 Maneuvers that
compromise
respiration
Preexisting neurological deficits
Patient refusal
Infection at the site of injection
Inability to communicate with pt
Sepsis
Coagulopathy or other bleeding diathesis

Oral Anticoagulants
 Long-term warfarin therapy
 Must be stopped
 Need PT/INR to be normalized
 Perioperative thromboembolic prophylaxis
 If initial dose given > 24 h prior to the block or if more than
one dose was given
 PT and INR need to be checked
 If only one dose given within 24 h
 Safe
 Removing an epidural catheter from patients receiving low-
dose warfarin (5 mg/d)
 Safe

Antiplatelets
 Aspirin and NSAIDs
 Alone don’t appear to increase risk of spinal hematoma
 More potent agents
 Ticlopidine (Ticlid)
 14 days
 Clopidogrel (Plavix)
 7 days
 Abciximab (Rheopro)
 48 h
 Eptifibatide (Integrilin)
 8 h

Unfractionated Heparin
 Minidose subQ prophylaxis
 OK to proceed
 Patients to receive heparin intraoperatively
 1 h or more before heparin administration
 A bloody epidural or spinal does not necessarily require cancellation of surgery
 discussion of the risks with the surgeon
 careful postoperative monitoring needed
 Removal of an epidural catheter
 1 h prior to dosing
 or 4 h following dosing
 Patients on therapeutic doses of heparin (elevated PTT)
 Avoid neuraxial
 The risk of spinal hematoma is undetermined in the setting of full anticoagulation
for cardiac surgery

LMWH (Enoxaparin, Dalteparin, -parin)
 Intro of Lovenox in the US in 1993
 Reports of spinal hematomas associated
with neuraxial anesthesia
 Many involved intraop or early postop use,
and several also taking antiplatelets
 If bloody needle or catheter placement occurs
 Delay until 24 hrs postop
 Postop LMWH thromboprophylaxis if epidural catheter in place
 Remove 2 hrs prior to the first dose
 Or 10 hrs after last dose and subsequent dosing should not
occur for another 2 hrs

Fibrinolytic or Thrombolytic Tx
 Best to avoid neuraxial.

Please note…
 Drugs/regimens not considered to put pts at
increased risk of neuraxial bleeding when
used alone (minidose subQ heparin, NSAIDS)
may in fact increase the risk when combined.

Which of the following statements regarding spinal
needle insertion is TRUE?
 A. The first significant resistance encountered when advancing a needle
using the paramedian approach is the interspinous ligament.
 B. If bone is repeatedly encountered at the same depth when the needle is
advanced, the needle is likely walking down the inferior spinous process.
 C. The midline approach is preferred in patients with heavily calicified
interspinous ligaments.
 D. Free flow of CSF after resolution of a paresthesia usually indicates that
the needle is in a good position.
 E. Penetration of the dura mater is more easily detected with a beveled
needle.

Answer
 D.
 If a paresthesia occurs you should immediately
stop advancing the needle and check for CSF.
 Obtaining CSF after resolution of a paresthesia
indicates the needle encountered a cauda equina
nerve root in the subarachnoid space and the
needle tip is in a good position.
 DO NOT inject LA in presence of a persistent
paresthesia!

Anatomic Approaches
 Spinous processes
 Cervical and lumbar spine – horizontal
 Needle directed with only a slight cephalad angle
 Thoracic spine – slant in a caudal direction and can overlap
 Needle angled significantly more cephalad
 First palpable cervical spinous process is C2
 Most prominent is…?
 C7
 Inferior tip of the scapula at level of …?
 Spinous process of T7
 Highest points of both iliac crests (Tuffier's line) ?
 Body of L4 or the L4–L5 interspace
 Posterior superior iliac spine
 S2 posterior foramina
 Sacral hiatus
 Depression just above or between the gluteal clefts and above the coccyx

Midline Approach
 Body positioned with the plane of the back perpendicular to the floor
 Palpate for depression between the spinous processes of the vertebra above and
below the level to be used
 Subcutaneous tissues offer little feeling of resistance
 Supraspinous and interspinous ligaments felt as an increase in tissue density
 If bone contacted superficially
 needle is likely hitting..?
 the lower spinous process
 If bone contacted at a deeper depth
 and needle is in the midline it is likely hitting…?
 the upper spinous process
 or if it is lateral to the midline it is likely hitting…?
 a lamina
 Ligamentum flavum - obvious increase in resistance
 At this point, spinal and epidural anesthesia differ

Paramedian Approach
 May be useful in certain patients
 severe arthritis
 kyphoscoliosis
 prior lumbar spine surgery
 2 cm lateral to the inferior aspect of
superior spinous process
 Penetrates the paraspinous muscles
 lateral to the interspinous ligaments
 needle may encounter little resistance
initially and may not seem to be in firm
tissue
 Needle advanced at a 10–25° angle
toward the midline
 LOR is often more subtle than with the
midline approach

 Bone encountered
deep
 lateral part of the
lower lamina
 redirected only
slightly upward,
more toward the
midline
 Bone at a shallow
depth
 medial part of the
lower lamina
 redirect mostly
upward and slightly
more lateral

Spinal Needles
 Available in an array of sizes (16–30 gauge), lengths,
and bevel and tip designs
 Tightly fitting removable stylet
 avoids tracking epithelial cells into the subarachnoid space
 2 broad groups
1. Sharp (cutting)-tipped
 Quincke needle is a cutting needle with
end injection
2. Blunt tip (pencil-point) needles
 Whitacre – rounded point with side injection
 Sprotte – rounded point with long side opening
 markedly decreased the incidence of PDPH

Spinal Catheters
 Very small subarachnoid catheters are currently no
longer approved in the US
 Association with cauda equina syndrome.
 Larger catheters designed for epidural use are
associated with relatively high complication rates
when placed subarachnoid.

Spinal Anesthesia
 Midline, paramedian, or
prone approach
 Two "pops" are felt:
 ligamentum flavum
 dura–arachnoid
membrane
 Successful dural
puncture confirmed by
free flow of CSF
 Persistent paresthesia
or pain upon injection
 withdraw and redirect
 Aspiration of CSF may
be necessary in certain
cases:
 presence of low CSF
pressure (dehydrated
patient)
 prone position

Which of the following statements is FASLE?
 A. A patient in the sitting position will have a higher
block if the solution is hypobaric and the patient remains
erect.
 B. A patient placed supine and in the Trendelenburg
position is at high risk for developing a total spinal block
after injection of an isobaric solution.
 C. A patient in the prone jackknife position should not
have a hyperbaric solution injected.
 D. The normal lumbar lordosis limits the spread of
hyperbaric solution is a supine patient.

Answer
 B.
 An isobaric solution should not ascend to
cause a total spinal regardless of the patient’s
position.

Factors Affecting the Level of
Spinal Anesthesia
 Baricity
 Position of the patient
 During and
immediately after
injection
 Dosage
 Site of injection
 Age
 CSF
 Curvature of the spine
 Drug volume
 Intraabdominal
pressure
 Needle direction
 Patient height
 Pregnancy
Most Important Factors Other Factors

Baricity 101
 A hyperbaric solution of local anesthetic is denser (heavier) than CSF
 Addition of glucose
 Hypobaric solution is less dense (lighter) than CSF
 Addition of sterile water
 Head-down position
 Hyperbaric solution - spreads cephalad
 Hypobaric anesthetic solution - moves caudad
 A head-up position
 Hyperbaric solution - settles caudad
 Hypobaric solution - ascends cephalad
 Lateral position
 Hyperbaric spinal solution - greater effect on dependent (down) side
 Hypobaric solution - higher level on nondependent (up) side
 Isobaric solution tends to remain at the level of injection

Baricity 101
 Hyperbaric solutions tend to move to the most dependent area of the
spine
 T4–T8 in the supine position
 Apex of the thoracolumbar curvature is T4
 In the supine position, this should limit a hyperbaric solution to
produce a level of anesthesia at or below T4
 Abnormal curvatures of the spine, such as scoliosis and kyphoscoliosis,
have multiple effects on spinal anesthesia
 Difficult landmarks
 Decreased CSF

Baricity 101
 CSF has a specific gravity of 1.003–1.008 at 37°C
Agent Specific Gravity
Bupivacaine
0.5% in 8.25% dextrose 1.0227–1.0278
0.5% plain 0.9990–1.0058
Lidocaine
2% plain 1.0004–1.0066
5% in 7.5% dextrose 1.0262–1.0333
Procaine
10% plain 1.0104
2.5% in water 0.9983
Tetracaine
0.5% in water 0.9977–0.9997
0.5% in D5W 1.0133–1.0203

Spinal Anesthesia
 CSF volume inversely correlates with level of anesthesia
 Increased intraabdominal pressure or conditions that cause
engorgement of the epidural veins, thus decreasing CSF
volume, are associated with higher blocks
 Pregnancy
 Ascites
 Large abdominal tumors
 Conflicting opinion exists as to whether
increased CSF pressure caused by
coughing or straining, or turbulence
on injection has any effect on the spread of LA

Spinal Agents
 Only preservative-free solutions used
 Addition of vasoconstrictors (epi or neo) and opioids may enhance the
quality and/or prolong the duration of spinal anesthesia
Drug Preparation DOA (plain) DOA (w/epi)
Procaine 10% solution 45 60
Bupivacaine 0.75% in 8.25%dextrose 90-120 100-150
Tetracaine 1% solution in 10%glucose 90-120 120-240
Lidocaine 5% in 7.5%glucose
(dilute to 2.5% or less)
60-75 60-90
Ropivacaine 0.2-1%solution
(Off-label use)
90-120 90-120

Spinal Agents
 Hyperbaric bupivacaine and tetracaine are two of the most commonly
used agents for spinal
 Relatively slow in onset (5–10 min)
 Prolonged duration (90–120 min)
 Similar sensory levels
 Tetracaine more motor blockade
 Addition of epi to bupivacaine prolongs its duration only modestly
 In contrast, epi to tetracaine prolongs by more than 50%
 Phenylephrine also prolongs tetracaine anesthesia but has no effect on
bupivacaine
 Ropivacaine
 Experience with spinals is more limited
 A 12-mg intrathecal dose of ropivacaine is roughly equivalent to 8 mg of
bupivacaine, but it appears to have no particular advantages for spinal
anesthesia

Spinal Agents
 Lidocaine and procaine
 rapid onset (3–5 min) and short duration of action (60–90
min)
 modest if any prolonged effect with epi
 Lidocaine associated with transient neurological
symptoms (TNS) and cauda equina syndrome
 TNS: back pain radiating to the legs without sensory or motor
deficits after resolution of spinal
 resolves spontaneously within several days
 Some experts suggest that lidocaine can be safely used
as a spinal anesthetic if the total dose is limited to 60
mg and diluted to 2.5% or less

Epidural Anesthesia
 The epidural space surrounds the dura mater posteriorly, laterally, and anteriorly
 Contents of Epidural Space:
 Nerve roots
 Fatty connective tissue
 Lymphatics
 Rich venous (Batson's) plexus
 Septa or connective tissue bands
 Epidural anesthesia is slower in onset (10–20 min) and may not be as dense as a spinal
 Can cause a pronounced differential or segmental block that can be useful clinically
 Relatively dilute concentrations of a LA combined with an opioid:
 Block the smaller sympathetic and sensory fibers and spare the larger motor fibers
 = analgesia without motor block
 Segmental block – LA not readily spread by CSF so confined close to level it was injected
 Characterized by a well-defined band of anesthesia at certain nerve roots
 Nerve roots above and below are not blocked
 Ex. thoracic epidural

Epidural Needles
 Typically 17–18 gauge
 9cm to hub
 Tuohy needle most commonly used
 Blunt bevel with a gentle curve of
15–30° at the tip
 Pushes away the dura after passing
through the ligamentum flavum instead
of penetrating it
 Straight needles without a curved tip
(Crawford needles) may have a higher
incidence of dural puncture but facilitate
passage of an epidural catheter.
 Needle modifications include winged
tips and introducer devices set into the
hub designed for guiding catheter
placement.

Epidural Catheters
 Continuous infusion or intermittent boluses
 May allow a lower total dose of anesthetic to be used
 Intraop and/or postop analgesia
 19- or 20-gauge catheter is introduced through a 17- or 18-gauge epidural needle
 Bevel opening directed either cephalad or caudad, and catheter advanced 2–6 cm
 The shorter the distance advanced:
 more likely it is to become dislodged
 The further the catheter is advanced:
 greater the chance of a unilateral block
 exiting the epidural space via an intervertebral foramen
 coursing into the anterolateral recesses
 Single port at the distal end or multiple side ports close to a closed tip
 Some have a stylet for easier insertion
 Spiral wire-reinforced catheters are very resistant to kinking
 The spiral or spring tip is associated with fewer, less intense paresthesias and may be
associated with a lower incidence of inadvertent intravascular insertion

Epidural Techniques
 LOR technique most commonly used
 Needle advanced through subQ tissues with the stylet in place
 Once interspinous ligament entered (increase in tissue resistance), stylet
removed
 Glass syringe filled with approximately 2 mL of fluid or air is attached
 If tip of needle is within the ligament, gentle attempts at injection are met
with resistance
 Needle slowly advanced, millimeter by millimeter, with either continuous or
rapidly repeating attempts
 As tip enters the epidural space there is a sudden LOR and injection is easy
 Hanging Drop Technique
http://www.youtube.com/watch?v=7kDi47vqBis
 Variation of Hanging Drop Technique
http://www.youtube.com/watch?v=TvCBDamF4jQ&feature=related

Activating an Epidural
 Quantity LA for epidural anesthesia is very large compared to spinals
 Significant toxicity can occur if injected intrathecally or intravascularly
 Safeguards against this: epidural test dose and incremental dosing
 Test dose detects both subarachnoid and IV injection
 Classic test dose: 3mL of 1.5% lidocaine with 1:200,000 epinephrine (5mcg/mL)
 45mg of lidocaine injected intrathecally – rapidly apparent spinal anesthesia
 15 mcg of epinephrine injected intravascularly – noticeable increase in heart rate (20% or
more) with or without hypertension
 False positives (uterine contraction causing pain or an increase in heart rate coincident to
test dosing)
 False negatives (patients taking beta blockers)
 25% or more increase in T-wave amplitude on EKG may be more reliable sign of IV injection
 Both fentanyl and larger doses of local anesthetic without epinephrine have been
advocated as intravenous injection test doses
 Simply aspirating prior to injection – insufficient to avoid inadvertent IV injection

Activating an Epidural
 Incremental dosing is a very effective method of avoiding
serious complications
 Fraction of the total intended LA dose, typically 5 mL
 Should be large enough for mild symptoms of IV injection to occur but
small enough to avoid seizure or cardiovascular compromise.
 If a clinician uses an initial test dose, is diligent about
aspirating prior to each injection, and always uses
incremental dosing, significant systemic toxicity or
inadvertent intrathecal injections are rare.

When using a caudal approach to the epidural
space, which of the following is TRUE?
 A. The patient must be prone.
 B. An inadvertent subarachnoid block is much
less likely than when using the lumbar approach.
 C. The technique becomes relatively more
contraindicated as the patient’s age decreases.
 D. Small volumes of agent are needed since the
volume of the canal is only 8-12ml.
 E. The needle enters through the sacral hiatus.

Answer
 E.
 Canal is of low volume but there is leakage through
the foramina requiring injection of a larger volume
compared to the lumbar approach.
 Pt can be prone or lateral decubitus.
 Inadvertent dural puncture is very possible.
 Caudal approach is technically easier than lumbar
approach in babies, and is becoming increasingly
more popular in pediatric anesthesia.

Caudal Anatomy
 Caudal space is considered the sacral portion of the epidural space
 Sacral vertebrae fuse into one large bone – the sacrum
 Each one retains discrete anterior and posterior intervertebral foramina
 Laminae of S5 and all or part of S4 normally do not fuse, leaving a
caudal opening to the spinal canal, the sacral hiatus
 Sacrococcygeal ligament covers the sacral hiatus

Caudal Anatomy
 Hiatus felt as a as a groove or notch above the coccyx
and between two bony prominences – the sacral cornua
 More easily appreciated in infants and children
 Posterior superior iliac spines and the sacral hiatus
define an equilateral triangle

Caudal Epidural Anesthesia
 One of the most commonly used regional
techniques in pediatric patients
 Used in anorectal surgery in adults
 2nd stage of labor
 In children - typically combined with GENA
for intraop supplementation and postop analgesia
 Performed after induction
 Commonly used for procedures below the diaphragm
 urogenital, rectal, inguinal, and lower extremity
 Within the sacral canal, the dural sac extends to…what level?
 S2 in adults
 S3 in infants
 Makes inadvertent intrathecal injection much more common in infants

Caudal Epidural Technique
 Position lateral or prone with one
or both hips flexed
 Palpate sacral hiatus
 Sterile skin prep
 Needle advanced at a 45° angle
cephalad until a pop is felt
(sacrococcygeal ligament)
 Angle flattened and advanced
 Aspirate for blood and CSF
 If negative, proceed with injection
 Test dose vs incremental dosing
with frequent aspiration

Caudal Anesthesia
 Complication rate for "kiddie caudals" is very low
 Total spinal and IV injection causing seizure or cardiac
arrest
 Intraosseous injection has also been reported to cause
systemic toxicity
 Calcification of the sacrococcygeal ligament may make caudal
anesthesia difficult or impossible
in older adults

Pediatric Caudal Anesthesia
 Dose: 0.5–1.0 mL/kg of 0.125–0.25% bupivacaine
(or ropivacaine) +/- epi
 Opioids may be added (ex 50–70 mcg/kg of morphine)
 not recommended for outpatients - delayed respiratory depression
 Duration can extend for hours into the postop period
 Ok to d/c home even with mild residual motor block or
without urinating
 most children will urinate within 8 h
 Higher epidural levels can be accomplished with
catheters threaded cephalad into the lumbar or
even thoracic epidural space

Caudal in Adults
 Dense sacral sensory blockade with limited
cephalad spread for anorectal procedures
 Prone jackknife position
 Dose 15–20 mL of 1.5–2.0% lidocaine +/- epi
 Fentanyl 50–100 mcg may also be added

All of the following statements regarding complications associated with
epidural and spinal anesthesia are true EXCEPT:
 A. Use of fluid instead of air for LOR during epidural
anesthesia reduces the risk of headache upon accidental dural
puncture.
 B. An epidural blood patch immediately relieves PDPH
symptoms in 99% of pts.
 C. Transient reduction in hearing acuity after spinal anesthesia
is more common in female than in male patients.
 D. Back pain is more common after epidural anesthesia than
after spinal anesthesia.
 E. Neurologic injury occurs in about 0.03% to 0.1% of all
central neuraxial blocks.

All of the following statements regarding spinal or epidural
anesthesia and spinal hematoma are true EXCEPT:
 A. Pts taking NSAIDS and receiving mini dose heparin are not
at increased risk.
 B. Pts treated with enoxaparin are at increased risk.
 C. Pts most commonly present with numbness or lower
extremity weakness.
 D. Spinal hematoma occurs at an estimated incidence of less
than 1:150,000.
 E. The removal of an epidural or an intrathecal catheter
presents nearly as great a risk for spinal hematoma as its
insertion.

Answer
 A
 Combination may put patients at increased
risk.

Adverse or exaggerated
physiological responses
 Urinary retention
 High block
 Total spinal anesthesia
 Cardiac arrest
 Anterior spinal artery syndrome
 Horner's syndrome
Complications related to
needle/catheter placement
 Trauma
 Backache
 Dural puncture/leak
 Postdural puncture headache
 Diplopia
 Tinnitus
 Neural injury
 Nerve root damage
 Spinal cord damage
 Cauda equina syndrome
 Bleeding
 Intraspinal/epidural hematoma
 Misplacement
 No effect/inadequate anesthesia
 Subdural block
 Inadvertent subarachnoid block1
 Inadvertent intravascular injection
 Catheter shearing/retention
 Inflammation
 Arachnoiditis
 Infection
 Meningitis
 Epidural abscess
Drug toxicity
 Systemic local anesthetic toxicity
 Transient neurological symptoms
 Cauda equina syndrome

3722183.ppt

Recommandé

Recommandé

Contenu connexe

Tendances

Tendances (20)

Similaire à 3722183.ppt

Similaire à 3722183.ppt (20)

Plus de MarkJohnson895316

Plus de MarkJohnson895316 (20)

Dernier

Dernier (20)

3722183.ppt

Notes de l'éditeur