5.3 Truncal Blocks & 5.4 IVRA Flashcards
Problems with uncontrolled acute pain
Uncontrolled acute pain is related to the development of chronic pain syndromes, post-operative myocardial ischemia and postoperative cognitive decline.
Post-operative pain relief after thoracic
surgery can be provided b
Post-operative pain relief after thoracic surgery can be provided by intercostal, interpleural, paravertebral and epidural
Intercostal block v Opiod
Compared with opioid analgesia,
intercostal block results in higher
peak expiratory flows.
PVB vs Epidural
Although epidural and paravertebral block (PVB) provides comparable analgesia after thoracic surgery, PVB has a better side-effect profile.
thoracic nerves
Level
Emerge from
thoracic nerves
T1–T12 emerge from their
respective intervertebral foramina,
and
divide into the
paired gray and white rami communicantes
(passing to the sympathetic
chain anteriorly)
posterior primary rami
(supplying paravertebral muscles)
anterior primary rami
(forming the ICN).
thoracic nerves
divide into the
divide into the
1
paired gray and white rami communicantes
(passing to the
sympathetic chain anteriorly)
2
posterior primary rami
(supplying paravertebral muscles)
3
anterior primary rami (forming the ICN).
ICN divides into
T12?
ICN divides into a
lateral and an
anterior cutaneous branch.
T12 is actually a
subcostal nerve rather
than an intercostal nerve
Location of ICN
1
In Paravertebral region
2
Medial to the angle of the ribs,
3 at angle rib
1
In the paravertebral region,
ICN overlies the parietal pleura and fat.
2 Medial to the angle of the ribs, ICN is sandwiched between the parietal pleural and posterior intercostal membrane (fascia of internal intercostals).
3 At the angle of the rib, the ICN lies between the intercostalis intimus (innermost intercostals) and internal intercostals.
Where ICN below inferior edge Rib
ICN lies in the intercostal groove
(along with intercostal vein and artery)
below the inferior edge of the rib.
T1 lacks lateral and anterior branches.
T2–T3 contribute to intercostobrachial nerve.
T12 (subcostal nerve) joins L1 to form iliohypogastric, ilioinguinal and genitofemoral nerves.
Evidence for ICN
vs
Epidural
Opiods
Good evidence for pain relief in…
Any good with chronic pain?
ICN block provides equieffective analgesia
as an epidural and significantly
better than opioids alone.
It provides excellent analgesia for
1.
fractured ribs,
and 2 pain relief after chest and 3 upper-abdominal surgeries (thoracotomy, thoracostomy, breast surgery, gastrostomy and cholecystectomy).
Chronic pain from post-mastectomy pain, post-thoracotomy pain, herpes zoster and tumour-related pain may also be treated
ICN technique
where
where best
why
ICNs are performed
proximally to the mid-axillary line,
as the
lateral cutaneous nerve arises beyond that point.
However, they are best performed
at the angle of the ribs,
ribs and intercostal spaces are thicker,
allowing a larger margin of safety
before pleura is contacted
ICN patient position
may be performed with patient in
supine or lateral position
(for mid-axillary injections),
but is best performed in prone position (for injection at the angle of the rib) with arms hanging by the sides to allow scapulae to rotate laterally, and a pillow under the abdomen to accentuate intercostal spaces posteriorly.
ICN technique
skin over the intercostal area is
retracted up and over the rib
and a 23–25-G needle is introduced
20° cephalad to come in contact with rib.
The needle is walked off the inferior edge,
maintaining the angulation,
and advanced 2–4 mm
into the intercostal groove.
Between 3 and 5 mL of local anaesthetic (LA) (0.5% bupivacaine) is injected after aspiration.
ICN salient points
Visceral pain
1 injection?
intercostal nerve block does not
block visceral pain, for which
coeliac or splanchnic plexus block may be needed.
Usually, multiple level injections are needed due to overlap of ICN
from above and below segments.
ICN complication
Complications may include pneumothorax (< 1%),
LA toxicity due to
rapid drug absorption
and spread to subarachnoid space
(because dural cuff may
extend up to 8 cm laterally).
Is there spread at single site injections
Injection at a single level may spread
to segments above and below
due to medial spread.
CT images have shown that the LA spreads
medially along the intercostal groove to the paravertebral space.
Interpleural block provides anaesthesia to
how does it work
does it spread to central
thorax
and
upper abdomen
Anaesthesia is attained by diffusion of LA to the nerves in proximity (intercostals nerves anteroposterolaterally, inferior roots of brachial plexus superiorly and the sympathetic chain, splanchnic, phrenic and vagus nerves medially).
The epidural and subarachnoid
spaces are distant and not felt to be the site of anaesthesia generally
Interpleural block
GA or Awake?
The block may be performed in an awake or anaesthetised spontaneously breathing patient (since positive-pressure ventilation may lead to positive intrapleural pressures),
Nitrous oxide should be subsequently discontinued if under general
anaesthetic.
in sitting, lateral or prone
position;
Interpleural block
Where is the injection site
How is it performed
at least 8–10 cm lateral to the midline
(to avoid dural cuff),
overlying the top edge of a rib.
Interpleural block
Is there sympathetic blockade
how does position affect
Because the spread of LA in the
interpleural space is governed
by gravity
(besides volume injected
and catheter position),
operative side up may produce
sympathetic blockade,
supine positioning results in
intercostals block and
head down may anaesthetise the inferior roots of
the brachial plexus
Interpleural technique
best used
Use in thoractomy?
Interpleural technique may be best used for
1 open cholecystectomy,
2 renal surgery and
3 unilateral breast procedures.
Thoracotomy is a controversial indication,
since duration of the
block is significantly
reduced when parietal pleura is open and a
thoracostomy tube is placed.
Interpleural vs ICN block
Although producing hemithoracic analgesia
and sympathetic block,
apart from minimising number of
injections require,
the analgesia is
less intense and of shorter duration
when compared to intercostal blocks
Complications Interpleural
Complications may include pneumothorax (2%), phrenic nerve paresis, Horner’s syndrome, ipsilateral bronchospasm and cholestasis.
Rectal sheath blocks provide analgesia
Rectal sheath blocks provide analgesia
for abdominal surgery
requiring a midline incision.
What is midline innervation
What are they branches of
Rectal sheath blocks
The midline area from xiphoid to pubis is innervated by the anterior cutaneous branches of T7–T11 nerves.
These terminal branches of ICN
ICN term branches
Where do they enter
terminate
Rectal sheath blocks
These terminal branches of ICN
enter the rectus sheath at its posterolateral border, and pierce the posterior sheath to cross rectus abdominis muscle, eventually terminating by supplying the overlying skin
Landmark Rectal sheath blocks
A 5-cm 22-G needle is
passed through skin and subcutaneous tissue
until it meets resistance
by the anterior rectus sheath.
The needle is carefully advanced to
pierce this sheath, through the belly of the
muscle.
As the needle approaches the
posterior rectus sheath, a firm
resistance is felt,
and 10 mL LA is deposited over it.
Rectal sheath block - does unilateral suffice?
Is there inferior spread to infraumbilical
The block requires
injections bilaterally due to overlap in innervations across the midline.
Also, tendinous insertions of rectus abdominis prevent
supraumbilical LA to spread to infraumbilical regions, mandating inferior injections.
It may be difficult to identify posterior rectus
sheath infraumbilically, and injection after loss of resistance of anterior
sheath may be safer and sufficient
Rectal sheat difficult?
Risks
It is difficult to perform in obese, cachexic, elderly (poor abdominal tone) and distended abdomen.
Deeper injections may
lead to bowel perforation or injury to underlying organs.
Nerves supplying the inguinal area
Subcostal (T12):
Iliohypogastric (T12, L1):
Ilioinguinal (L1):
Genitofemoral (L1 and L2):
Subcostal (T12):
Subcostal (T12):
Lies between internal oblique
and external oblique at the
anterior superior iliac spine
Area around iliac crest
Iliohypogastric (T12, L1):
detail
Iliohypogastric (T12, L1):
Emerges from lateral border of psoas
and passes over quadratus lumborum
to penetrate transverse abdominal muscle
near the iliac crest
It lies between internal oblique
and external oblique at the
anterior superior iliac spine
Skin over ilium, hypogastric and
suprapubic region
