The document provides information on performing an ultrasound-guided ilioinguinal/iliohypogastric nerve block, including:
1) The technique involves using an ultrasound probe to locate the nerves between the internal oblique and transversus abdominis muscles, and injecting 0.1 mL/kg of 0.25% bupivacaine with epinephrine around the nerves.
2) Potential complications include perforation of abdominal walls or bowels, which can be avoided by using blunt needles and appreciating loss of resistance.
3) Prolonged postoperative analgesia is possible using continuous catheters placed near the nerves connected to infusion pumps.
2. Ilioinguinal/Iliohypogastric Nerve
Block
• The ilioinguinal/iliohypogastric nerve block is indicated for inguinal hernia,
orchidopexy, and varicocele surgery.
• Technique : A line is drawn between the umbilicus and anterior superior iliac
spine. A point is marked 2 mm medial from the anterior superior iliac spine.
The needle is advanced toward the inguinal canal and passed in until a
“pop” is felt. Local anesthetic solution is then injected into the area after
aspiration. US studies have shown that blind administration usually does
not inject the local anesthetic into the correct fascial plane between the
internal oblique and transversus abdominis muscles; yet, clinically, the
majority of blocks work, presumably due to the diffusion of the local
anesthetic.40 Alternatively, an ilioinguinal nerve block can be performed by
the surgeon; the disadvantage of this is the need for a deeper plane of
general anesthesia intraoperatively.
3. Ultrasound-Guided Technique
• The probe is placed on a line from the anterior superior iliac spine to the
umbilicus, with the lateral end of the probe resting on the bone. With
practice, the nerves can be tracked more proximally toward the midaxillary
line, which prevents the local anesthetic spreading too far into the surgeon’s
field and disrupting their tissue planes. Experts in this field have managed
to successfully block these nerves with a volume of local anesthetic as little
as 0.075 mL/kg.
6. Strategy of Procedure
• Ultrasound Probe : Use either high frequency linear probe or hockey stick
probe. Either probe can be used, but hockey stick probe may be more
effective for infants and young children since the nerves are closely situated
beneath the skin.
• Anesthetic Agent : 0,25% bupivacaine with epinephrine (1:200.000)
To avoid profound motor block, use 0,125%. Duration will be the same, but motor
block will be less.
• Weight of anesthetic dose : 0,1 ml/kg
• Confer with surgeon :
Identify site specificity
Discuss transient femoral nerve block
7. Prepare for Block
• Palpate for anterior superior iliac spine.
• Equipment that are needed :
27 gauge needle
Betadine prep
Bupivacaine 0,25% with 1:200.000 epinephrine
Sterile dry gauze
Sterile field area
Rolling cart/MAYO tray
Sterile gloves
• Locate nerves between internal oblique and transversus abdominis
• Pull back plunger to 1 mL mark to check for possible intravascular injection
9. Handling Post-Operative Adverse
Events
• Lipid Rescue
Lipid Infusion Therapy is an apparently effective treatment for the most
devastating complication of regional anesthesia : cardiovascular collapse from local
anesthetic overdose. The Lipid Sink Theory explains the effect by postulating that
the lipophilic local anesthetics are absorbed into the infused lipid, thus preventing
their toxic effect on the tissue. Recent research suggest that there may be another
mechanism for effect.
• Reaction :
20% intralipid : 1,5 ml/kg as an initial bolus, followed by 0.25 ml/kg/min for
30-60 minutes. Bolus could be repeated 1-2 times for persistent asystole.
Infusion rate could be increased if the BP declines.
10. Indications & Contraindications
• Indications for ilioinguinal/iliohypogastric blocks include anesthesia for any
somatic procedure involving the lower abdominal wall/inguinal region such
as inguinal herniorrhaphy and for analgesia after surgical procedures using
a Pfannenstiel incision as for cesarean section7 and abdominal
hysterectomy. These blocks do not provide visceral anesthesia and thus
cannot be used as the sole anesthetic for procedures such as lower
intraabdominal surgery. When used for inguinal herniorrhaphy, the sac
(containing peritoneum) must be infiltrated with local anesthetic by the
surgeon to complete anesthesia for the procedure.
• There are no specific contraindications for these blocks apart from the
generic contraindications to performance of any regional block such as
infection at the procedure site, allergy to local anesthetics, indeterminate
neuropathy, and so on.
11. Complications & How to Avoid
• An ilioinguinal/iliohypogastric nerve block is relatively safe. Perforation of
the bowel wall can occur, however, and has been reported. Femoral nerve
blockade may occur in up to 11% of cases; therefore, all ambulant children
should be tested for weight bearing prior to discharge.
• The mechanism of femoral anesthesia with these methods is tracking of local
anesthetic along the fascia iliaca. In the event of femoral anesthesia
associated with ilioinguinal/iliohypogastric blocks, the surgeon is notified
and the patient is advised to protect the lower extremity until the block
recedes.
• Perforation of both the small and large bowels and creation of a pelvic
hematoma have been reported after ilioinguinal/iliohypogastric blocks. This
illustrates the importance of using blunt needles to appreciate the loss of
resistance as the needle traverses the layers of the abdominal wall.
12. Continous
Ilioinguinal/Iliohypogastric Blocks
• Prolonged postoperative analgesia for procedures using a Pfannenstiel
incision has been successfully produced using bilateral catheters. Such
catheters are an excellent alternative to epidural analgesia by allowing
unlimited ambulation without the need for urinary catheterization. Control
of visceral pain with NSAIDS or other agents is necessary to complete
analgesia.
• From a point 2 cm medial and 2 cm cephalad from the anterior superior iliac
spine, an 18-gauge Tuohy-type needle is inserted in a slightly medial and
caudal orientation to the skin to pierce the external oblique muscle. After
loss of resistance, a multilumen catheter is inserted and directed medially
for 5 cm and secured to skin. The procedure is repeated on the other side.
The catheters are either infused using separate pumps or a single pump
with flow-restrictor catheters that allow accurate individual catheter flow
are used. Individual catheter flow rates of 4 mL/h (0.2% ropivacaine) have
been used.
