12.1 TAP Block Flashcards
TAP block -
Indications
Benefit
TAP block provides pain relief to the anterior abdominal wall (not effective for visceral pain) from T7 to L1 level.
Spread above the umbilical level is unreliable, so it is useful for any surgery involving anterior abdominal wall
where the incision is below the level of the umbilicus:
> > Abdominal hysterectomy.
Caesarean section.
Retropubic prostatectomy.
Inguinal hernia repair
(will not cover areas supplied by ilioinguinal and
iliohypogastric nerves).
Appendicectomy.
Lower abdominal open colorectal surgery.
Laparoscopic surgery.
Potential benefits:
» Part of a multimodal analgesia approach,
reducing dependence on other
modes of analgesia and their
associated adverse effects.
> > Reduced opioid requirement,
useful in patients for whom opioids may be
undesirable, for example those with respiratory disease.
> > May avoid the need for neuraxial technique
in patients in whom this is contraindicated,
e.g. patients with coagulopathy
(however, unlikely to be
as effective as neuraxial technique).
> > Offers pain relief after emergency caesarean,
where urgency has not permitted neuraxial technique.
c) Outline how you would perform a TAP block. (40%)
Ultrasound (US) guided:
> > Consent, assess for contraindications,
skilled assistant, resuscitation drugs,
venous access, assemble equipment,
aseptic technique, full monitoring.
> > US machine,
high-frequency linear array probe
(curvilinear may be required
in obese patients),
sterile cover, 0.5% chlorhexidine spray,
sterile US gel,
50–100 mm block needle,
20–40 ml local anaesthetic (LA), 10 ml saline.
> > Clean patient skin; allow to air dry.
> > Patient supine. US probe transverse
to the orientation of the patient, in
midaxillary line between the ribs and iliac crest.
> > In-plane introduction of needle to reach
the space between the internal
oblique and transversus abdominis.
> > Inject saline to confirm that the needle is in the correct plane, then inject LA in 5-ml aliquots,
aspirating prior to each injection, watching
transversus abdominis plane expand with injection.
> > Bilateral blocks required for midline
incisions and incisions that cross the midline.
Landmark:
» Preparation as for ultrasound-guided technique.
» The Triangle of Petit should be identified by palpation of the iliac crest
inferiorly, the anterior border of latissimus dorsi posteriorly and the
posterior border of the external oblique anteriorly.
» A 50-mm block needle is usually sufficient as a more direct approach to
the plane is taken.
» The needle is inserted perpendicularly to the skin in the Triangle of Petit
just above the iliac crest in the posterior axillary line.
» Two pops are felt as the needle passes through the fascial extensions of
the external and then internal oblique.
» Aspiration should be negative prior to injection.
d) What are the specific complications of a TAP block? (15%)
Don’t just write ‘nerve damage, bleeding, failure’ – explain the issues associated with this particular block.
> > Failure –
there is significant variation in degree of
local anaesthetic spread with TAP block.
> > Local anaesthetic toxicity –
large volumes of local anaesthetic are used,
especially if bilateral block.
> > Risks of incorrect site of injection
much reduced with the use of ultrasound but
include
intraperitoneal injection,
intrahepatic injection,
bowel perforation or haematoma.
> > Transient femoral nerve block.
a) Describe the innervation of the
anterior abdominal wall. (20%)
The anterior rami of
T7–T12 and L1 lie between
internal oblique and transversus abdominus
and supply the anterior abdominal wall.
Cutaneous branches of these then
pierce the rectus sheath to supply overlying skin.
> > T7–9 supply superior to the umbilicus.
> > T10 supplies the periumbilcal area.
> > T11–12 with iliohypogastric and ilioinguinal nerves supply the area inferior to the umbilicus.
> > Iliohypogastric: L1 origin.
Supplies the inguinal region.
> > Ilioinguinal: L1 origin.
Supplies the inguinal hernia
sac as well as scrotum/
labia and medial aspect of thigh.
