Epidurals, Spinals, and
More
Table of Contents
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Anatomy
Techniques
Side Effects
Concerns of anticoagulation
Anatomy
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Epidural
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Local anesthetics injected into the epidural space spread in cranial and
caudal directions from the level at which they are administered.
The drug bathes the nerve roots as they pass through the anterolateral
epidural space, but roots above and below the limit of spread of local
anesthetic remain unaffected.
This gives an epidural local anesthetic block a top and a bottom level of
effect, with the site of injection somewhere in between.
There may be preferential spread of local anesthetic to one side of the
spinal canal, and when this occurs the level and intensity of blockade on
each side of the body can be different.
Occasionally single nerve roots are missed altogether resulting in a patchy
block.
Local anesthetic solutions injected into the epidural space are influenced by
gravity. With the patient in a sitting position the lower segments tend to be
blocked, and when supine the block spreads higher. In the lateral position,
the dependent side tends to block preferentially
Friendly advice to pregnant
anesthesia residents
Positioning
Procedure
A new twist for the Sitting position
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In the mid-calf position, the patient
rests the lower legs (mid-calf),
rather than the knees, on the edge
of the bed, sitting somewhat further
back on the bed than in the
conventional sitting position. As a
result, the knees are slightly flexed
with the patient’s back nearer to
the practitioner. The patient’s neck
is flexed forward and the arms are
crossed in front of the body (Fig. 1).
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One advantage of the mid-calf
position is that the patient naturally
assumes an ideal position for
placement of a neuraxial block with
little instruction. The shoulders fall
forward and the flexed position
achieved appears to optimally open
the spaces between the spinous
processes
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British Journal of Anaesthesia 2006 97(4):583-584;
doi:10.1093/bja/ael231
Technical Difficulty
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The fatness- most
problematic: get a
harpoon and a lucky
charm
Old people suck- calcified
ligaments and arthur is in
town: you may have to
abandon procedure
Prior back surgery- Heavy
Metal
Autoimmune + collagen
d/o - have ligaments like
paper don’t slip or you
might get a spinal tap
Technical Difficulty
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Kyphoscoliosis: this gentleman
looks virtually impossible to place
neuraxial anesthesia but clinicians
used Taylors approach for spinal
anesthesia
In the sitting position, the right
posterior superior iliac spine (PSIS)
was identified. A point 1cm below
and medial to the PSIS was
marked, Using a Quincke type
spinal needle, the site was entered
in cephalomedial direction. Dural
puncture was successful at the
second attempt.
In patients where a midline
approach at the lumbar level is
difficult, the lumbosacral approach
is an excellent alternative for
providing spinal anesthesia to
perineal and lower extremity
surgery
M.G.M. Medical College
Indore Madhya Pradesh India
Tattoos
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A Medline and EMBASE search of
the English literature using the key
words: spinal, epidural, tattoos,
tattooing, complications did not
find any reports or concerns
regarding neuraxial anesthesia
through tattooed areas. However,
one might postulate that there
could be long-term implications
from depositing a pigmented tissue
core in the epidural or
subarachnoid space.
Based on the limited information
available it is possible that inserting
an epidural or spinal needle
through a tattoo could cause longterm problems such as
arachnoiditis or a neuropathy
secondary to an inflammatory
reaction, but we don’t know.
Canadian Journal of Anesthesia
49:1057-1060 (2002)
Epidural catheter placed detected by
flouroscopy
Spinal
Physiological effect of spinal
blockade at different levels
Differences
CSE Z
CSE Failure
Caudal
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Block of the sacral and lumbar
nerve roots. It is useful as a
supplement to general
anesthesia and for provision of
postoperative analgesia. This
technique is popular in
pediatric patients. Catheter
insertion may be performed for
continuous caudal block.
The S5 processes are remnants
and form the cornua, which
provide the main landmarks for
indentifying the sacral hiatus.
The hiatus is covered by the
sacro-coccygeal membrane.
The canal contains areolar
connective tissue, fat, sacral
nerves, lymphatics, the filum
terminale and a rich venous
plexus.
Caudal Injection for Pain patients
Caudal epidural anesthesia in
children can be used in
Lower abdominal surgery: (incision below the umbilicusT10 sensory level)
especially perineal, genitourinary or ilioinginual surgery.
Lower extremity surgery (hip, leg and foot): though at times it is difficult to
achieve a satisfactory block to the distal 1/3 of the foot.
Newborn and premature infants: If used as the sole anesthetic, caudal
epidural anesthesia reduces the risk of respiratory depression from residual
neuromuscular blockade (pancuronium) and inhalation anesthetics. Postoperative apnea associated with general anesthesia, is reduced with caudal
anesthesia but not abolished.
Neuromuscular disease such as muscular dystrophy. There is a high
incidence of postoperative respiratory failure due to a combination of
general anesthesia and muscle weakness. Caudal epidural anesthesia
indicated for lower extremity surgery (very common in these patients).
Malignant hyperthermia: it is generally accepted that all local anesthetic
agents are considered safe
Caudal Doses
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Pediatric population
0.5 ml/kg, 0.25% bupivacaine
(sacro-lumbar block)
1 ml/kg, 0.25% bupivacaine
(upper abdominal block)
1.2 ml/kg,0.25% bupivacaine
(mid-thoracic block)
(Doses described by Armitage).
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Adults: 20-30 ml 0.25-0.5%
bupivacaine. Average volume of
the sacral canal is 30-35 ml.
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Epidural fat in children has a
loose and wide-meshed texture,
whereas in adults it becomes
more densely packed and
fibrous. Hence, local anesthetic
spread is greater in children.
Caudal Placement Position
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The sacral hiatus in an
infant or young child is
easily identified because the
landmarks are more
superficial. The sacral hiatus
is formed by failure of
fusion of the fifth sacral
vertebral arch. The remnants
of the arch are known as the
sacral cornu, and are located
on either side of the hiatus.
Caudal Block Technique
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The needle is inserted at a 60-degree
angle and the needle is advanced until a
"pop" is felt. The needle is then lowered to
a 20-degree angle and advanced an additional
2-3 mm to make sure the bevel is in the
caudal epidural space
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The pop felt is the needle
piercing the sacrococcygeal
membrane
There should be very little
resistance to injection.
The dura ends at S2, but may
extend further. Aspirate to
confirm the absence of
blood/cerebrospinal fluid and
inject local anesthetic while
feeling for inadvertent
subcutaneous injection with the
other hand
In children, the block typically
performed after general
anesthesia has been induced and
before surgery has commenced
Caudal
Neuraxial Contraindications
Effects of Neuraxial anesthesia
Complications and side effects of
neuraxial methods
Blood Patch
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The epidural blood patch
consists of injecting 5-20 mLs of
autologous blood into the
epidural space, in the region of
the suspected dural 'hole.'
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Autologous blood is typically
drawn in a sterile fashion, and
then injected as a bolus into the
epidural space.
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In 90% of cases, the response is
positive and immediate.
Subsequently, long-term relief
of PDPH occurs in the majority
of cases
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PATIENTS ON HEPARIN THERAPY
There should be at least a 1-h delay between neuraxial needle placement
and heparin administration.
The epidural catheter should be removed 2–4 h after the last heparin dose
and 1 h before subsequent heparin administration.
Partial thromboplastin time (PTT) or activated coagulation time (ACT)
should be monitored to avoid excessive heparin effect.
Dilute concentrations of local anesthetics are recommended to minimize
motor blockade; the patient should be followed postoperatively for early
detection of reoccurrence of motor blockade.
In the event of a traumatic (bloody) or difficult needle placement, there are
no data to support mandatory cancellation of surgery.
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PATIENTS RECEIVING LMWH AND NEURAXIAL ANESTHESIA
Monitoring of anti-Xa level is not recommended.
The administration other anticoagulant medications with LMWHs may increase the
risk of spinal hematoma.
The presence of blood during needle placement and catheter placement does not
necessitate postponement of surgery. However, the initiation of LMWH therapy
should be delayed for 24 h postoperatively.
The first dose of LMWH prophylaxis should be given no earlier than 24 h
postoperatively and only in the presence of adequate hemostasis.
In patients who are on LMWH, needle/catheter placement should be performed at
least 12 h after the last prophylactic dose of enoxaparin or 24 h after higher doses of
enoxaparin (1 mg/kg every 12 h), 24 h after dalteparin (120 U/kg every 12 h or 200
U/kg every 12 h), and 24 h after tinzaparin (175 U/kg daily).
There should be a 12-h interval between the last prophylactic dose of enoxaparin
and removal of the epidural catheter. For higher doses of enoxaparin, a 24-h delay
is recommended.
The LMWH may be administered
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Summary of Guidelines on Anticoagulants and Neuraxial Blocks I. Antiplatelet medications
Aspirin, NSAIDs, COX-2 inhibitors
May continue
Pain clinic patients: Aspirin preferably stopped 2–3 days in thoracic and cervical blocks
Epidurals (author’s preference—see text)
Thienopyridine derivatives
a. Clopidogrel (Plavix)—discontinue for 7 days
b. Ticlopidine (Ticlid)—discontinue for 14 days Do not perform a neuraxial block in patients on more than one antiplatelet
drug.
GPIIB/IIIA inhibitors: Time to normal platelet aggregation
a. Abciximab (Reopro) = 24–48 h
b. Eptifibatide (Integrilin) = 4–8 h
c. Tirofiban (Aggrastat) = 4–8 h
Antiplatelet medications (ASA, Plavix) are usually given after GPIIb/IIIa inhibitors. The above guidelines on aspirin and
Plavix should be adhered to.
II. WarfarinCheck INR
INR ≤ 1.5 before neuraxial block or epidural catheter removalIII. Heparin
Subcutaneous heparin (5000 units SQ q 12 h)
Subcutaneous heparin is not a contraindication against a neuraxial block
Neuraxial block should preferably be performed before SQ heparin is given
Risk of decreased platelet count with SG heparin therapy > 5 days
Intravenous heparin
Neuraxial block: 2–4 h after the last intravenous heparin dose
Wait ≥ 1 h after neuraxial block before giving intravenous heparin
IV. Low-molecular-weight heparin (LMWH)
No concomitant antiplatelet medication, heparin, or dextran
LMWH Preop
a. Wait 12 h before a neuraxial block:
b. Enoxaparin (Lovenox) 0.5 mg/kg bid (prophylactic dose)
c. Wait 24 h before a neuraxial block:
d. Enoxaparin (Lovenox), 1 mg/kg bid (therapeutic dose)
e. Enoxaparin (Lovenox), 1.5 mg/kg qd
f. Dalteparin (Fragmin), 120 units/kg bid
g. Dalteparin (Fragmin), 200 units/kg qd
h. Tinzaparin (Innohep), 175 units/kg qd
LMWH Postop:
a. LMWH should not be started until after 24 h after surgery
b. LMWH should not be given until ≥ 2 h after epidural catheter removal
Patients with epidural catheter who are given LMWH
The catheter should be removed at the earliest opportunity.
Enoxaparin (0.5 mg/kg): Remove the epidural catheter ≥ 12 h after last dose.