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367
Introduction adhistory
Uses of the femoral nerve
are documented in the lite
allows blockade of three ne:
oral nerve, the lateral fei
and the obturator nerve,
Anesthesia and analgesia c
Figure 1
Anatomy
Femoral vein
Femoral artery
Skin
Fascia lata
00
Table I
Surgical procedures amenable to femoral nerve
block/3-in-1 block
1. Unilateral saphenous vein stripping
2. Knee arthroscopy*
3. Muscle biopsy of anterior thigh'
4. Split thickness skin graft
'Supplemented with lateral femoral cutaneous nerve block
Table II
Pain management uses of the femoral nerve block/
3-in-i block
1. Femur fractures
2. Anterior cruciate ligament reconstruction
3. Split thickness skin grafts of thigh*
4. Osteotomies'
5. Pin or plate insertion or removal*
*Supplemented with lateral femoral cutaneous nerve block
Fasia ilia
&~pwasFemoral nerve
Pectineus muscle
~musc
,p
vastus medialis, and vastus intermedius.
The lateral femoral cutaneous nerve is formed
by the posterior division of L2 and L3 and emerges
slightly more proximal than the femoral nerve from
the lateral border of the psoas muscle. The lateral
Figure 3
Landmarks
femoral cutaneous nerve is a purely sensory nerve
with branches supplying the lateral buttock, thigh,
and the knee joint.'"'
The obturator nerve is formed by the ventral
branches of L2, L3, and L4. It emerges from the
medial border of the psoas muscle. Sensory
branches to the medial thigh may or may not occur.
Other branches innervate the hip joint, external
obturator, gracilis, and adductor muscles, and an
articular branch innervates the knee joint'"'
(Figure 2).
igure
V-Femoral vein
A-Femoral artery
FN-Femoral nerve
Solid line-Inguinal ligament
i
SCutaneous innervation
Lateral femoral
cutaneous nerve
Obturator nerve
(inner thigh)
".. Femoral nerve
]UH Saphenous nerve
Techniques of femoral nerve block and 3-in-i
block
There are four basic techniques for blocking
the femoral nerve at the level of the inguinal ligament. The landmarks are the same for all four of
the techniques (Figure 3). With the patient in the
supine position, the anterior superior iliac spine
and the symphysis pubis are identified. An imaginary line between these structures will identify
where the inguinal ligament lies. Next, the femoral artery is palpated below the inguinal ligament.
A 22-gauge 2 to 4-cm (1 to 2 in) needle is inserted
perpendicular to the skin immediately lateral to
the femoral artery.
In the first technique, the needle is advanced
until maximum pulsation of the needle occurs or a
August 1998! VoL 66/No. 4
paresthesia is elicited.' A second, technique elicits
no paresthesia or pulsations and utilizes a short
beveled needle. Identification of proper placement
is based on two "pops." This indicates that the needle has crossed the fascia lata and fascia iliaca."
A third technique of identification of the nerve is
the use of a peripheral nerve stimulator and identification of quadriceps contraction. A fourth technique is to deposit local anesthetic in a fanwise
fashion lateral to the femoral artery.'
No studies have compared the four techniques
in terms of successful blockade. We have found that
the peripheral nerve stimulator is easily administered, positively identifies the femoral nerve, and
reduces the chance of nerve damage by "seeking"
paresthesias.
An inguinal paravascular block or 3-in-i block
is carried out in the same manner except that the
needle is directed slightly cephalad, and distal pressure is maintained to force the local anesthetic cephalad instead of in a distal direction.' The difference between a femoral nerve block and a 3-in-i
block is related to the. volume of local anesthetic. It
has been reported that anywhere between 5 and
20 mL"3'35," of local anesthetic can be used for a
femoral nerve block, whereas 20 mL or more'l 33 s"
of local anesthetic is used for a 3-in-i block. The
more volume used, the more the local anesthetic
solution will travel to anesthetize additional nerves
and provide for a denser block.
s itreally a34n-1 block?
Controversy has characterized discussions of
the 3-in-i block. Is it a 4-in-i block, 3-in-i block, or
369
2-in-i block? 37 The anterior approach to the 3-in-i
block by paresthesia and nerve stimulation was effective in blocking the lateral femoral cutaneous
nerve and the femoral nerve but consistently missed
the obturator nerve. It was proposed that the dose
of 0.5 mL/kg of local anesthetic did not travel far
enough proximally or laterally to block the obturator nerve.4 ' A second study found that the obturator nerve was blocked only 4% (1 out of 26) of the
time.12 The original description by Winnie et al of
shortest total time (mean * SD) for short stay at
271 t 43 minutes, the time for the general anesthesia group was 292 ± 62 minutes, for the lidocaine spinal group, 298 * 75 minutes, and for the
bupivacaine spinal group, 371 t 85 minutes. Of
the patients who received a femoral nerve block,
31% (5 out of 16) complained of pain during the
PACU stay compared with 47% (8 out of 17) in the
spinal group and 72% (13 out of 18) of those in the
general anesthetic group.
more of local anesthetic would assure anesthesia of
After discharge to home, 31% (5 out of 16) of
the patients who received femoral nerve block re-
the lateral femoral cutaneous, femoral, and the obturator nerves. 3 Winnie et al did not describe how
ported pain compared with 47% (8 out of 17) of
those who received a spinal block and 38% (7 out of
the 3-in-i block indicated that volumes of 20 mL or
the block was tested.3
Interestingly, different results utilizing 20 mL
and 40 mL of a 1% concentration of mepivacaine
were found in another study concerning blockade
of the obturator nerve. The obturator nerve was
blocked 62% (24 out of 39) and 78% (33 out of 41),
respectively.4 This difference may be due to different evaluation techniques used in the studies.
18) who received general anesthesia. In addition,
there was no incidence of backache or nausea and
vomiting in the femoral nerve block group. In the
spinal anesthetic group, the incidence of backache
was 6% (1 out of 18) and nausea and vomiting, 12%
(2 out of 17). In the general anesthetic group, the
incidence of backache was 16% (3 out of 18) and
nausea and vomiting, 28% (4 out of i8).4
In one study, the authors utilized a test of motor
Femoral nerve blocks combined with a lateral
and sensory blockade, 4 and in the other study, only
sensory evaluation was undertaken. 3
The spread of methylene blue after 3-in-i
blocks in six cadavers was studied" After dissection, it did not appear that the dye traveled along
the femoral nerve, and there was no gross or microscopic evidence of a femoral sheath. The dye
spread under the iliacus fascia laterally over the
iliopsoas and iliacus muscles. The dye did not
spread medially into the pelvis and did not reach
the obturator nerve since the iliacus fascia is attached to the pelvic rim."
femoral cutaneous nerve block have been used in
pediatrics for postoperative pain relief, with a success rate of 96% for orthopedic procedures and skin
grafts in the distribution of the femoral nerve and
lateral femoral cutaneous nerves.5 The blocks were
placed after induction of general anesthesia. No
complications were noted. Oral analgesics were
commenced when the patient was awake to prevent
the onset of severe pain when the block wore off.5
Femoral nerve block supplemented with a lateral
femoral cutaneous nerve block has been advocated
for skin grafting procedures. The advantages over
Based on the anatomical evidence and review
local infiltration include a requirement for less total
of literature, we conclude that the 3-in-i nerve block
would be best described as a 2-in-i nerve block or a
combined femoral nerve and lateral femoral cuta-
anesthetic agent, less discomfort with administra-
neous nerve block.
Uss of femoral neve block
A comparison of general anesthesia, spinal anesthesia, and femoral nerve block in patients who
underwent unilateral saphenous vein stripping was
undertaken.4 The technique for general anesthesia
was not described; bupivacaine or lidocaine was
utilized for spinal block, and 3% chloroprocaine
was used for femoral nerve block. The mean 1 SD
time in the postanesthesia care unit (PACU) was
the shortest for the general anesthesia group at
69 f 21 minutes; the time in PACU after femoral
nerve block was 85 33 minutes, and the spinal
anesthetic group had a PACU time of 100 = 30 minutes for lidocaine and 128 ± 56 minutes for bupivacaine. The femoral nerve block group had the
370
tion, less distortion, and a lack of moisture from a
local anesthetic to interfere with dermatome glue.6
,
A case report demonstrated the effectiveness
of continuous femoral nerve block for postoperative pain management in a 13-year-old boy who
had surgery for patella alta.' The femoral catheter
was inserted after general anesthesia was instituted.
The upper thigh was prepared aseptically, and a
small incision was made lateral to the femoral artery immediately below the inguinal ligament. An
18-gauge 5-cm intravenous catheter was threaded
over a 22-gauge spinal needle and advanced
through the incision parallel to the artery at a 300
angle to the skin.The position was confirmed with
a nerve stimulator and movement of the patella.
The catheter was sutured and connected to sterile
extension tubing, and a sterile occlusive dressing
was applied. On the first postoperative day, an injection of 15 mL of 0.75% bupivacaine was admin-
Journalof the American Association of Nuse Anesthetists
istered every 6 hours. On the second day, a continuous infusion of 0.5% bupivacaine at 4 mL/h was
started. The infusion concluded 24 hours later. Negative cultures were obtained from the local anesthetic reservoir and distal catheter. No complica-
pop occurred, the needle and guide wire were
removed, and the catheter was advanced. After negative aspiration, a bolus of 0.5 mL/kg of 0.25% bu-
The periosteum of the femur is innervated primarily by the femoral nerve. The distal and proximal portions of the femur contain contributing innervation from the obturator nerve and sciatic
nerve. Although other analgesic and anesthetic
techniques could be utilized for femur fractures,
the femoral nerve block is the indication that is
most frequently cited in the literature. 8-"2 For children who had a fracture of the middle third of the
femoral shaft, utilization of a femoral nerve block
with 0.5% bupivacaine at a dose of 2 mg/kg provided rapid analgesia within a mean + SD time
of 8 ± 3.5 minutes."3
The femoral nerve block was placed with the
subject awake after the skin was anesthetized with
1%lidocaine. All subjects had a pain rating grade
of 3 (crying, pain expressed spontaneously, and
handling impossible) or 4 (crying, tachycardia
greater than 60% of normal rate for age, and handling is impossible) before the femoral nerve block.
After the block, the pain grade decreased to 0 (calm,
no spontaneous pain or pain during handling) for
85% (11 out of 13) of the subjects and to 1 (calm, no
spontaneous pain, pain during handling) for 15%
(2 out of 13) of the subjects. The exact duration of
femoral nerve block could not be determined since
traction had a definitive analgesic effect. Traction
placement occurred at a mean ± SD of 124 -* 19
minutes after the femoral nerve block. The block
was successful in 93% (14 out of 15) of the subjects."~
Femoral nerve block for fractured femurs was
most effective for fractures of the middle third of
the femur in a study of 25 adults and children.' 5
Pain relief was obtained at the proximal and distal
portions of the femur but was not as complete due
to contributions of innervation by the obturator
nerve and sciatic nerve.' 4 It has been recommended
that femoral nerve blocks should be used for patients who sustained femoral neck fractures. Although the block does not abolish pain, it greatly
reduces pain and the need for systemic analgesia."-5
Continuous femoral nerve block in pediatric patients was effective in providing analgesia and decreasing or eliminating the need for parenteral narcotics after femur fracture.' 6 After sterile skin preparation, a 3F, 8-cm single-lumen central venous
catheter was inserted using the Seldinger technique.
The catheter was placed 2 to 4 cm below the inguinal ligament just lateral to the femoral artery. A
double pop technique was used. Once the second
patients had a continuous infusion for 4 to 6 days
tions were noted.7
August 1998/ VoL 66/No. 4
pivacaine with 1:200,000 epinephrine was administered, followed by a continuous infusion of 0.2%
bupivacaine at a rate of 0.15 mL/kg per hour. Three
and required no supplemental analgesia. One patient had a continuous infusion for 4 days but required two doses of fentanyl for supplemental
analgesia. 6
Four advantages for the use of the femoral
nerve block in patients who have sustained fractured femurs have been cited.' First, the block provides superior analgesia compared with narcotics,
in part by preventing the protective spasms of the
quadriceps muscle. Second, the block allows for
assessment of associated injuries without adminis-
tering medications that alter the level of consciousness. Third, the patient can be moved for radiological procedures without experiencing severe pain.
Fourth, with some sedation when indicated, the
fracture can be reduced and splinted without the
use of general anesthesia."
The use of the femoral nerve block for postoperative analgesia after total knee arthroplasty has
not been consistently effective. The knee joint is
also innervated by the sciatic and obturator nerves,
reducing the effectiveness of analgesia by this
technique.8 "9
Femoral nerve block for analgesia after surgery on the knee ligament decreased analgesic
requirements in the immediate postoperative
period.' At 12 hours postoperatively, there was
no difference in use of analgesics between those
who received a femoral nerve block and those who
did not. Fanwise infiltration of local anesthetic was
performed 2.54 cm (1 in) below the inguinal ligament immediately lateral to the femoral artery. The
authors used 20 mL of 0.25% bupivacaine.o The
concentration of bupivacaine, the volume, or both
may have been inadequate.
Postoperative analgesic requirements in patients undergoing anterior cruciate ligament repair were compared.2" One group of 50 subjects
who received a femoral nerve block with 20 mL of
0.5% bupivacaine by infiltration before surgery was
compared with a control group, which received no
block. For the group that received the femoral nerve
block, intramuscular narcotic requirements were
decreased by 80% in the recovery room and by 40%
during the first 24 hours after surgery. A second
portion of this study compared preoperative and
postoperative placement of the femoral nerve block.
A 50% decrease in the use of intramuscular narcotics -in the recovery room and during the first 24
postoperative hours was found. Only 10
were used in each group.2 No power
anal
done to determine whether there is really
ence between the two groups or whether t]
ing was due toa larger variability in a small
nephrinE
ported fc
ul use of 0.5% bu
a dose of2 to 3
ostoperative pain
tients un(
cruciate
room. Eight percent of the subjects required parenteral narcotics after the femoral nerve block, and
21% required ketorolac after the femoral nerve
blockYn A dose of 2 to 3 mg/kg of 0.5% bupivacaine
in a 70-kg adult would result in volumes of 28 to
42 mL and should be termed a 3-in-i block and not
a femoral nerve block.
Femoral nerve block combined with lateral
femoral cutaneous nerve block in patients undergoing muscle biopsy for testing of malignant hyperthermia susceptibility has been used successfully. The technique provided safe and effective
anesthesia for 282 patients. 2
A 3-in-i block could be used for procedures
that utilize a femoral nerve block with supplemental lateral femoral cutaneous nerve block and would
reduce the need for additional injections. As noted,
when the 3-in-i nerve block successfully blocked
the femoral nerve, the lateral femoral cutaneous
nerve was blocked in 96% (25 out of 26) of the
patients.2
a 70
Uses of 3-In-I block
The use of the 3-in-i block, with 20 mL of 2%
chloroprocaine and 1:200,000 epinephrine, combined with an intra-articular injection of 20 mL of
2% lidocaine provided excellent anesthesia for knee
arthroscopy.26 Patient satisfaction was measured by
asking the patient to grade satisfaction on a scale of
1 (very satisfied) to 5 (unsatisfied). Patient satisfaction was very high, with a mean * SD score of
1.5 f 0.5. Surgical operating conditions were
graded by the surgeon on a four-point scale; 1 indicated excellent and 4, unacceptable. None of the
subjects required a general anesthetic.
A single-injection 3-in-i block was compared
with a 3-in-i block combined with a separate block
of the lateral femoral cutaneous nerve and with
general anesthesia for knee arthroscopies. The authors used 20 to 25 mL of 1.5% mepivacaine or lidocaine for the 3-in-i block. In the group of patients who received a 3-in-I block, 27% (18 out of
30) had pain during the lateral knee incision. In
the group that received a supplemental lateral fem-
1372
[ject+
pen
analgesia a
fixation wa
found that
first 12 hours, while all the sub
receive a block required analgesi
in analgesic usage during the
tween the groups was statisti
(P<.05).
The 3-in-i nerve block has
utilized as the sole anesthetic in
ing muscle biopsy of the vastus n
nant hyperthermia
testing,'
util
Journal of the American Association of Nurse Anesthetists
47,48
used.'~Plasma~ levels were measured and reported
in one case report and three studies. In the case
report, a 54-kg female patient received an accidental overdose of 180 mg of 0.5% bupivacaine. The
peak venous plasma level was noted at 0.92 pg/mL
and occurred 45 minutes after injection 41 One study
tracked the venous blood samples in six patients
for each local anesthetic group. The subjects received 0.6 mL/kg of 1% lidocaine or 0.25% bupivacaine with 1:100,000 epinephrine, up to a maximum of 40 iL. 31 The median peak plasma level in
the lidocaine group was 1.85
Table III
Contraindications to femoral nerve block/3-in-1 block
1. Burn or infection at site of injection
2. Vascular graft to femoral artery
3. Coagulopathy
4. Neurological disease
5. Patient refusal
Table IV
Complications of femoral nerve blockl3-in-1 block
1. Hematoma
2. Intravascular injection
3. Femoral nerve dysesthesia or paresis
4. Femoral nerve palsy
5. Toxic effects of the local anesthetic
6. Prolonged motor blockade of quadriceps
7. Methemoglobinemia with the use of prilocaine
;
_;;;
August 1998 Vol 66/No. 43
;.-;; ; ;
pg/nL
(range,
1.22-4.42 pg/mL). The median peak plasma level
for the bupivacaine group was 0.67 ug/mL (range,
0.35-0.80 pg/nL). Both groups had a median peak
concentration 37.5 minutes after the block was
inserted."1
A second study utilized a bolus of 2 mg/kg or
0.5% bupivacaine in 10 children followed by a
continuous infusion of 0.25% bupivacaine at
0.35 mg/kg per hour.3 The median venous plasma
concentrations of bupivacaine did not exceed
1.2 pg/iL, and the maximal peak concentration
was 2.1 pg/mL. No patient exhibited signs of
toxicty. 30 Nine children received 2 mg/kg of 0.5%
bupivacaine for management of pain for fractures
of the middle third of the femur. Plasma bupivacaine levels were studied in subjects weighing a
mean * SD of 25.3 f 10.6 kg, and in all but one
subject, levels were lower than 1.2 pg/nL. One sub-
ject had a level of 1.52 jpg/nL, which was attributed to a partial intravascular injection.3 The established threshold for toxicity for bupivacaine is
373
2 to 4 pg/mL and for lidocaine is 5 to 10 dg/mL.
The third study utilized 35 mL of 0.75%
prilocaine for postoperative analgesia in patients
who had a fractured head of the femur that was
corrected with a compression screw or pin and
plate.27 For 12 patients in whom plasma prilocaine
levels were obtained, the peak levels were lower
than the suggested threshold of 6 pug/mL for
toXicity. 27
Prolonged femoral nerve blocks with motor
blockade of the quadriceps have been noted after
the use of bupivacaine.4 9 In the first case report,
0.5% bupivacaine was given in a dose of 180 mg
instead of 0.25% bupivacaine. No signs of systemic
adverse effects were noted. The motor blockade
lasted for 30 hours, and discharge was delayed.49 In
a second case, 20 mL of 0.25% bupivacaine was used
for pain management after knee arthroscopy. Quadriceps weakness persisted for 8 hours, and discharge
was delayed until the next day.5 In a third case,
30 mL of 0.5% bupivacaine was injected, and the
patient experienced a motor blockade that lasted
36 hours and a sensory blockade that lasted 60
hours. 5 ' In a fourth case, 15 mL of 0.5% bupivacaine was injected, and the patient experienced
some loss of quadriceps function, which returned
to normal by 40 hours.52
In none of these cases was there any neurological damage, and quadriceps weakness resolved
when the bupivacaine wore off. Bupivacaine is inappropriate in same-day surgical procedures when
the patient will need to use the quadriceps. However, if the patient's leg will be immobile and the
patient will use crutches, this technique may be
appropriate if the patient is informed about the
duration of blockade. The use of prilocaine for
3-in-i block may lead to methemoglobinemia.59
Further studies
Clearly there is room for further study and
research concerning these nerve blocks. Some of
the areas that we believe deserve study include:
1. A comparison of the four techniques of
blockade and the success rate of each blockade.
2. Optimal dosing of lidocaine or mepivacaine
in the outpatient population to avoid residual weakness of the quadriceps.
3. Whether preincision placement of the 3-in-i
nerve block reduces postoperative analgesics more
than placing the block at the end of surgery.
4. What dose of local anesthetic is required to
consistently block the lateral femoral cutaneous
nerve during a 3-in-i nerve block.
5. Cost-effectiveness of blocks compared with
other modalities of postoperative pain management.
374
Conclusions
The literature describes a number of uses for
these blocks in anesthesia and analgesia. These
blocks are technically easy to administer by appropriately trained anesthesia providers utilizing the
correct equipment and technique. Renewing our
interest in these blocks may allow us to utilize these
blocks as viable alternatives to other methods of
anesthesia and analgesia. Selective use of these techniques and further studies are required, but we
should certainly not discount these blocks in our
practice.
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AUTHORS
Daniel D).Moos, CRNA, MS, is employed by Kearney Anesthesia
Associates, PC. and practices at Good Samaritan Hospital in Kearney,
Nebraska.
James D. Cuddeford, CUNA, MA, is program director of the Bryan
Memorial Hospital/Univeristy of Kansas School of Nurse Anesthesia,
Kansas City, Kansas.
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