Transcript The femoral nerve block

Presented by
Marwa A. Khairy
Assistant Lecturer of Anesthesia & intensive care
Faculty of Medicine-Ain Shams University

1.
2.
3.
4.
All about lumbar plexus anatomy are true
except:
Formed mainly by anterior rami of L1-L4
Receive contribution from S1-S2
Embedded in the psoas ms
Supplies the posterior aspect of the thigh.

The lumbar plexus Block landmark:
At the PSIS
At the Midline
At point 4 cm lateral to intersection between
midline & intercrestal line
4. At L2-L4 vertebrae
1.
2.
3.

1.
2.
3.
4.
Lumbar plexus Block
Advanced technique
High volumes are needed
Hemodynamic instability is a potential problem
Not used in anticoagulated patients

The femoral nerve
Formed by the anterior divisions of the anterior
rami of L2–L4.
2. Supply the adductors of the thigh
3. Supply the medial aspect of the lower leg via the
saphenous nerve.
4. it is positioned immediately lateral and slightly
deeper than the femoral artery
1.

The femoral nerve block
The first sign of onset of blockade is the loss of
sensation of the skin over the medial aspect of the
leg below the knee (saphenous nerve).
2. Typical onset time for this block is 10-15 minutes
3. Visible twitch of the quadriceps muscle) at 0.2-0.5
MA current is the optimal response.
4. Carry high risk of postoperative falls.
1.
•Introduction
•Anatomy
•Distribution of anesthesia
•Patient positioning
•Equipment
•Nerve stimulator guided technique
•US guided technique
•Complications

The lumbar plexus block is an advanced nerve
block technique.

The block has significant clinical applicability and
because of this, it is used commonly in our practice.

However, this block has a relatively higher potential
for complications and should be practiced only after
appropriate training




Anterior, medial, and lateral procedures of the thigh
including harvest of skin grafts, malignant
hyperthermia (MH)-biopsy procedure.
Knee replacement,
Total hip replacement ,hip fractures.
Anterior and posterior cruciate ligament
reconstruction.
Anatomy of
Lumbar Plexus
•The
lumbar plexus is
formed by the anterior rami
of the first four lumbar
nerves;
it
frequently
includes a branch from T12
and occasionally from L5.
•The
plexus lies between
the psoas major and
quadratus
lumborum
muscles in the so-called
psoas compartment.
Anatomy of
Lumbar Plexus
•The
lumbar plexus is
formed by the anterior rami
of the first four lumbar
nerves;
it
frequently
includes a branch from T12
and occasionally from L5.
•The
plexus lies between
the psoas major and
quadratus
lumborum
muscles in the so-called
psoas compartment.
Distribution
of Anesthesia
•The
femoral nerve supplies
motor fibers to the quadriceps
muscle (knee extension), skin
of the anteromedial thigh, and
the medial aspect of the leg
below the knee and foot.
•The
obturator nerve sends
motor branches to the
adductors of the hip and a
highly variable cutaneous area
on the medial thigh or knee
joint.
•The
lateral femoral cutaneous
and genitofemoral nerves are
purely cutaneous nerves
Patient
Positioning
•The
patient is in the
lateral
decubitus
position with a slight
forward tilt.
•The
foot on the side
to be blocked should
be positioned over
the dependent leg
so that twitches of
the patella can be
seen easily.
Equipment
•A standard
regional
anesthesia tray is prepared
with the following
equipment:
•Sterile towels and 4"x4"
gauze packs
•20-mL syringes with local
anesthetic
•Sterile gloves, marking
pen, and surface electrode
•One 1½" 25-gauge needle
for skin infiltration
•A 10-cm long, short bevel,
insulated stimulating needle
•Peripheral nerve stimulator
Landmarks
Landmarks for the
lumbar plexus block
include:
•Iliac crest
•Midline (spinous
processes)
Needle insertion 4cm lateral to the
intersection of
landmarks 1 and 2
Landmarks
Landmarks for the
lumbar plexus block
include:
•Iliac crest
•Midline (spinous
processes)
Needle insertion 4cm lateral to the
intersection of
landmarks 1 and 2
Technique
Local anesthetic
skin infiltration
After a cleaning with
an antiseptic
solution.
Technique
•The needle
is
inserted at a
perpendicular angle
to the skin.
•The nerve
stimulator should be
initially set to deliver
1.5 mA current.
Technique
•As the needle
is
advanced, local
twitches of the
paravertebral
muscles are
obtained first at a
depth of a few cms.
Technique
•The
needle is then
advanced further until
twitches of the quadriceps
muscle are obtained
(usually at the depth of 68 cm).
• After the twitches are
obtained, the current
should be lowered to
obtain
stimulation
between 0.5 mA and 1.0
mA.
•At this point, 25-35 mL of
local anesthetic is slowly
injected with frequent
aspiration to rule out
inadvertent intravascular
placement of the needle.
•.

Requires a relatively large volume of local anesthetic

The choice of the type and concentration of local
anesthetic should be based on whether the block is
planned for surgical anesthesia or pain management.

Due to the highly vascular nature of the area there is high
potential for inadvertent intravascular injection, rapid
absorption from the deep muscle beds, and epidural
spread

Adequate sedation and analgesia are necessary to ensure
a still and tranquil patient.

Typically, we use midazolam 4-6 mg after the patient is
positioned and alfentanil 500-1000 µg just before needle
insertion.

A typical onset time for this block is 15-25 minutes,
depending on the type, concentration, and volume of local
anesthetic and the level at which the needle is placed.

The first sign of the onset of blockade is usually the loss of
sensation in the saphenous nerve territory (medial skin
below the knee).
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Infection
Hematoma (should not be performed in anticoagulated pts)
Nerve injury
Vascular puncture
Local Anesthetic Toxicity
Hemodynamic consequence (Spread of the local anesthetic to
the epidural space may result in significant hypotension and occurs in as many as
15% of the patients)
US Guided
Ultrasound Landmarks:
The transverse processes
of the third and fourth
lumbar vertebrae and the
psoas muscle.
Transducer Type:
Linear or curved array, 3
to 7 MHz
Transducer Position:
Sagittal plane, 4 to 5 cm
lateral to the posterior
spinous process of the
fourth lumbar vertebra
US Guided
Longitudinal sonogram
of the lumbar
paravertebral region
showing
an optimal scan for
lumbar plexus block
the ‘trident
sign’.
•Introduction
•Anatomy
•Distribution of anesthesia
•Patient positioning
•Equipment
•Nerve stimulator guided technique
•US guided technique
•Complications

An 83-yr-old woman (70 kg ) is admitted to the emergency room
after a fall in her nursing home. She has fractured the neck of her
femur, but otherwise there is no trauma. In addition, she has many
medical problems, including coronary artery disease, hypertension,
and chronic obstructive lung disease.

On examination, she was cooperative and orientated for time and
place. HR 100 atrial fibrillation, blood pressure (BP) 170/100. The
electrocardiogram (ECG) shows old MI change with left-axis
deviation. Room oxygen saturation is 91%. Her chest is clear, except
for crepitations at the bases and increased respiratory wheeze.

Because she is orientated for time and place, she
requests a spinal anesthetic, as she is worried
about going to sleep. You are happy to oblige and
explain that she must either sit up or lie on her side
for you to do the spinal. She absolutely refuses and
claims this will be very painful.

You attempt to sit her up, but she complains of severe
pain. You give her midazolam 0.5 mg and fentanyl 50 mg,
slowly. A little later she claims to feel better. However, her
oxygen saturation has now fallen to 87% on room air. You
give her supplemental oxygen and her saturation improves
to 93%. You attempt to sit her up again, but she complains
bitterly. You could use a small dose of ketamine so that you
can place the spine in a lateral position, but you are
concerned about a potentially unacceptable increase in BP
with ketamine and the need to use atropine with its side
effects.

What else could you do to make her pain free. so
that you can perform the spinal block?

You can perform a femoral nerve block


Femoral nerve block is a basic nerve block
technique that is easy to master.
It carries a low risk of complications, and has a
significant clinical applicability for surgical
anesthesia and post-operative pain management.
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Anterior thigh surgery
ACL repair
Knee arthroscopy (+ intra-articular local)
Femur surgery
Knee arthroplasty (pain management only)
Anatomy
•The femoral nerve,
formed by the dorsal
divisions of the
anterior rami of L2–
L4, is the largest
terminal branch of
the lumbar plexus.
Anatomy
•The
femoral nerve
passes underneath
the inguinal ligament
into the thigh.
• As
the
femoral
nerve
passes
underneath
the
inguinal ligament, it
is
positioned
immediately lateral
and slightly deeper
than the femoral
artery
Anatomy
•At
the femoral crease, the
nerve it is covered by the
fascia iliaca and separated
from the femoral artery and
vein by a portion of the
psoas muscle and the
ligamentum ileopectineum.
•This
physical separation of
the femoral nerve from the
vascular fascia explains the
lack of the spread of a
"blind
paravascular"
injection
of
local
anesthetics toward the
femoral nerve.
After emerging from the ligament, the femoral nerve
divides into an anterior and posterior branch. At this level it
is located lateral and posterior to the femoral artery
anterior branch
posterior branch
Motor
Motor
Sartorius and pectineus ms
quadriceps muscles
Sensory
Sensory
skin of the anterior and
medial aspect of the
medial thigh
lower leg via the
saphenous nerve

Distribution of
Anesthesia
A femoral block results
in anesthesia of the
entire anterior thigh and
most of the femur and
knee joint.
 The block also confers
anesthesia of the skin on
the medial aspect of the
leg below the knee joint
(saphenous nerve - a
superficial terminal
extension of the femoral
nerve).
Patient
position
The patient is in the
supine position with both
legs extended.
 In obese patients, a
pillow placed underneath
patient's hips may
facilitate palpation of the
femoral artery and block
performance.
Patient
position
The patient is in the
supine position with both
legs extended.
 In obese patients, a
pillow placed underneath
patient's hips may
facilitate palpation of the
femoral artery and block
performance.
Equipment
Sterile towels and 4"x4"
gauze packs
20 mL syringes with
local anesthetic
Sterile gloves, marking
pen, and surface
electrode
One 1½" 25-gauge
needle for skin infiltration
A 5-cm long, short
bevel, insulated
stimulating needle
Surface electrode
Peripheral nerve
stimulator
Landmarks
Landmarks
for the
femoral nerve block
are
easily
recognizable in all
patients and include:
•Femoral crease
•Femoral
artery
pulse
Landmarks
Needle
insertion
site is labeled
immediately lateral
to the pulse of the
femoral artery.
All landmarks
should be outlined
with a marking pen
Technique
After a thorough
cleaning with an
antiseptic solution,
local anesthetic is
infiltrated
subcutaneously at
the estimated site of
needle insertion.
Technique
The anesthesiologist is
standing on the side of
the patient with the palpating hand on the
femoral artery.
The nerve stimulator is
initially set to deliver 1.0
mA (2 Hz, 100 µsec).
The needle is
introduced immediately
at the lateral border of
the artery and advanced
in the saggital and
slightly cephalad plane
Technique
The
femoral
nerve innervates
a number of
muscle groups.
A
visible or
palpable twitch of
the quadriceps
muscle (patella
twitch) at 0.2-0.5
mA current is the
optimal response.

A femoral block can be accomplished with as little as 10
mL of local anesthetic. However, we often use larger
volumes of local anesthetic (e.g., 20-25 mL), because the
local anesthetic often disperses underneath fascia iliaca
laterally and results also in block of the lateral femoral
cutaneous nerve of thigh.

The choice of the type and concentration of local
anesthetic should be based on whether the block is
planned for surgical anesthesia or pain management.

Long-acting local anesthetic should be avoided in
ambulatory patients undergoing relatively minor
procedures as ambulation is affected by prolonged motor
block of the quadriceps muscle.

Minimal patient discomfort

However, many patients feel uncomfortable being
exposed.

Sedation is necessary for the patient's comfort and
acceptance. Midazolam 1-2 mg after patient is positioned
and alfentanil 250-500µg just before the local infiltrations
suffices for most patients.

A typical onset time for this block is 10-15 minutes,
depending on the type, concentration, and volume of local
anesthetic used.

The first sign of onset of blockade is the loss of sensation
of the skin over the medial aspect of the leg below the
knee (saphenous nerve).

Weight bearing on the blocked side is impaired and this
should be clearly explained the patient to prevent the risk
of falls.





Infection
Hematoma
Nerve injury
Vascular puncture
Others (falls)
US Guided
Ultrasound
Landmarks:
The femoral artery and
the femoral nerve. The
nerve lies lateral or
occasionally deep to the
artery.
US Guided
Transducer Type:
10 to15 MHz linear array
Transducer Position:
The probe is located in
the axial plane along the
inguinal crease
US Guided
The femoral nerve
appears as a
hyperechoic
flattened oval
structure lateral to
the femoral artery.
US Guided
The spread of the local
anesthetic can be
visualized in real time as
hypoechoic solution
surrounding the femoral
nerve, and the needle tip
is repositioned if
required to ensure
appropriate spread.





Indications: Hip, anterior thigh, and knee surgery
Landmarks: Iliac crest, spinous processes
(midline)
Nerve stimulation: Twitch of the quadriceps
muscle at 0.5-1.0 mA current
Local anesthetic: 25-35 mL
Complexity level: advanced





Indications: Anterior thigh and knee surgery
Landmarks: Femoral (inguinal) crease, femoral
artery pulse
Nerve Stimulation: Twitch of the patella
(quadriceps) at 0.2-0.5 mA current
Local anesthetic: 20 mL
Complexity level: Basic

1.
2.
3.
4.
All about lumbar plexus anatomy are true
except:
Formed mainly by anterior rami of L1-L4
Receive contribution from S1-S2
Embedded in the psoas ms
Supplies the posterior aspect of the thigh.

The lumbar plexus Block landmark:
At the PSIS
At the Midline
At point 4 cm lateral to intersection between
midline & intercrestal line
4. At L2-L4 vertebrae
1.
2.
3.

1.
2.
3.
4.
Lumbar plexus Block
Advanced technique
High volumes are needed
Hemodynamic instability is a potential problem
Not used in anticoagulated patients

The femoral nerve
Formed by the anterior divisions of the anterior
rami of L2–L4.
2. Supply the adductors of the thigh
3. Supply the medial aspect of the lower leg via the
saphenous nerve.
4. it is positioned immediately lateral and slightly
deeper than the femoral artery
1.

The femoral nerve block
The first sign of onset of blockade is the loss of
sensation of the skin over the medial aspect of the
leg below the knee (saphenous nerve).
2. Typical onset time for this block is 10-15 minutes
3. Visible twitch of the quadriceps muscle) at 0.2-0.5
MA current is the optimal response.
4. Carry high risk of postoperative falls.
1.