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
Ilioinguinal (L1):
detail
Ilioinguinal (L1):
Emerges from the lateral border
of the psoas major
just inferior to the iliohypogastric,
and passes obliquely across the
quadratus lumborum and iliacus
It then perforates the
transversus abdominis
near the anterior
part of the iliac crest,
to lie between it and
internal oblique initially,
and then between internal oblique
and external oblique
medial to the anterior superior iliac spine
Travelling through the spermatic,
it emerges from the superficial
inguinal canal
Skin over medial aspect of thigh Skin over the root of the penis and upper part of the scrotum (male) and skin covering the mons pubis and labium majus (female)
the ilioinguinal nerve does not pass through the deep inguinal ring, and
therefore it only travels through part of the inguinal canal. The genital branch
of the genitofemoral nerve passes through both deep and superficial inguinal
rings
Genitofemoral (L1 and L2):
detail
Genitofemoral (L1 and L2):
In abdomen, it descends on
anterior surface of psoas and then
divides into genital and femoral branches
The genital branch travels through
the inguinal canal, along
with the spermatic cord to emerge at the superficial inguinal ring
Genital branch innervates cremaster
muscle and gives twigs to scrotum
and adjacent thigh
Femoral branch passes under
inguinal ligament and supplies skin
of femoral triangle
inguinal block mcq points
What arises from L1
Where does iliohypogastric lie
Where does ilioinguinal lie
1
Iliohypogastric and ilioinguinal nerves arise from L1 spinal nerve root
2
Iliohypogastric nerve lies between internal and external oblique at the anterior superior iliac spine
3.
Ilioinguinal nerve lies between
transversus abdominis and
internal oblique initially,
and between internal and external oblique medial to the anterior superior iliac spine
inguinal block constitutes blocking
4 nerves
Inguinal block constitutes blocking the
subcostal,
iliohypogastric,
ilioinguinal
and the genitofemoral nerves.
The block may not provide
total anaesthesia for inguinal
herniorrhaphy if the last nerve is not
blocked
Inguinal block
whats blocked at ASIS
subcostal, iliohypogastric and ilioinguinal nerves are all blocked medial to anterior superior iliac spine (ASIS).
A skin puncture point 1– 2 cm medial
and 1–2 cm inferior to ASIS is infiltrated with LA.
A blunt needle is advanced at
right angles to the skin in all planes.
Inguinal block landmark
iliohypogastric
details
As the needle pierces the external oblique, a characteristic ‘click’ is
felt, and 6–8 mL of LA is incrementally deposited to anaesthetise the
iliohypogastric.
Inguinal block landmark
Ilioinguinal
Advancing the needle pierces the internal oblique, resulting in a
second ‘click’. A further 6–8 mL of LA is injected incrementally to
block the ilioinguinal.
Inguinal block landmark
Subcostal
Redirecting the needle towards ilium at this point will allow
infiltration of LA (3–5 mL) to lateral branches of subcostal nerve.
A subcutaneous infiltration made towards the midline blocks the medial
branches of subcostal nerve.
Genitofemoral nerve is blocked by
Genitofemoral nerve is blocked by
inserting the needle 2–3 cm above
the mid-inguinal point to a depth of
3–5 cm,
injecting 10–15 mL of LA.
This may also be done by the
surgeon after exposing the spermatic cord.
Inguinal block uses
This block may be used for inguinal herniorrhaphy, groin surgery and post-operative analgesia for lumbar spinal canal stenosis (bilateral ilioinguinal block).
Inguinal block complications
Complications may include haematoma formation,
LA toxicity, femoral nerve block (5%) and rare bowel perforation.
The transversus abdominis plane (TAP) exist
The transversus abdominis plane (TAP) exists
between internal oblique
and transversus abdominis
muscles in the abdominal wall.
TAP initially describrd
What is the name of the region
What are its boundaries
The TAP block was first described
as a landmark-guided technique involving
needle insertion
at the triangle of Petit by McDonnell et al.
This is an area bounded by the
latissimus dorsi muscle posteriorly,
the external oblique muscle anteriorly
and
the iliac crest inferiorly
(the base of the triangle).
TAP technique landmark
A needle is inserted
perpendicular to all planes,
looking for a tactile
end point of two pops.
The first pop indicates penetration of the
external oblique fascia and entry into the plane between external and internal oblique muscles.
The second pop signifies entry into the TAP
plane between internal oblique and transversus abdominis muscles.
TAP where does it anaesthetise
Deposition of LA
(large volume, 20–30 mL each side)
at this plane leads to anaesthesia of nerves supplying the anterior abdominal wall
(T7–L1).
Detail about debate over how it works and what its suitable for
It has been shown to provide good post-operative analgesia for a variety of procedures.
Nerves of T6–T9 enter the TAP medial to the
anterior axillary line.
Nerves running in the TAP lateral to the anterior
axillary line, on the other hand,
originate from segmental nerves T9–
L1. This may explain the observation of some authors that the TAP
block is only suitable for lower-abdominal surgery. Therefore, TAP
injections are made posterior to the mid-axillary line in the
landmark-based technique. Such injections are thought to act by
tracking paravertebrally. However, injections made anterior to the
mid-axillary line may behave as field blocks (and therefore have
limited duration and effect)
TAP Variations
More recently, ultrasound-guided techniques of TAP block have been described.
A variation of the classic TAP block, the subcostal TAP block, has also been described; it is designed to provide more reliable coverage of the upper abdominal wall.
The quadratus lumborum block
The quadratus lumborum block is an ultrasound-guided block into
the quadratus lumborum space. It describes a space posterior to the
abdominal wall muscles and lateral to the quadratus lumborum muscle.
It has been used in abdominoplasties, Caesarean sections and lower
abdominal operations, providing complete pain relief in the
distribution area from T6 to L1 dermatomes.
Where is local deposited in TAP
Superior to TA
Deep to IO
Where DO ICN lie
the intercostal nerves lie
in the intercostal groove
below the inferior edge
of the corresponding ribs.
Inguinal block landmark
Performing the inguinal block needs
the ASIS to be identified and then
injection 2 cm medial and 2 cm inferior to it.
TAP landmark
TAP block is performed at the triangle of Petit above the iliac crest posterior to the mid-axillary line.
PVB landmark
The transverse process of the
vertebrae is the critical bony structure
required to perform paravertebral block.
Paravertebral block (PVB) block of
Paravertebral block (PVB) refers to the blockade of spinal nerves as they exit the intervertebral foramen.
The thoracic paravertebral space is
PV space boundary
wedge-shaped area on either side of the spine
posteriorly by superior costotransverse ligament,
laterally by posterior intercostal membrane,
anteriorly by parietal pleura
and
medially by the
posterolateral aspect of
vertebral body,
disc and intervertebral foramen
PV space division
endothoracic fascia
divides this space into
two potential fascial compartments:
1 the anterior extrapleural
paravertebral compartment and
2 the posterior subendothoracic
paravertebral compartment.
PV Space content
Its contents are ventral ramus (intercostal nerve), dorsal ramus, rami communicantes, sympathetic chain (anteriorly) and fatty tissue.
It is contiguous with
epidural space medially and intercostal space laterally.
Lumbar PV space
The lumbar paravertebral space
lacks costotransverse ligaments.
It is bound
anterolaterally by psoas muscle,
medially by
vertebral body,
disc and intervertebral foramen,
and posteriorly by transverse process
and its ligaments.
It is primarily occupied by psoas muscle
Thoracic v Lumbar PVB
Where does the spinal nerve leave
In thoracic and lumbar regions,
the spinal nerves leave the
intervertebral foramen
inferior to the transverse process of its
corresponding vertebra.
For example, the L4 spinal nerve exits
between the L4 and L5 vertebrae.
Performing a PVB
landmark
needle
insertion
redirection
issue with this technique in lumbar region
Performing a PVB requires
insertion of a Tuohy needle (18 G) at the
level of a spinous process,
3 cm lateral to the midline to contact the
transverse process at a depth of 2–4 cm.
It is then walked off (caudally
or cephalad)
by 1–2 cm to reach the paravertebral space.
This may be
identified by LOR as the needle
pierces the superior costotransverse
ligament.
The lumbar paravertebral space lacks costotransverse
ligaments, rendering this technique useless.
PVB thoracic
Spinous process shape
How does this affect technique
In the thoracic region,
the tip of the spinous process lies
at the level of the transverse process below it,
due to its steep downward angulation.
Hence the needle must be
directed cephalad to walk off the transverse
process to block the corresponding spinal nerve,
PVB lumbar region
whereas in the lumbar region,
the tip of the spinous process lies
at the level of the transverse
process of the same vertebrae
as it is almost horizontally directed.
Hence the needle is directed
caudally to walk off the transverse
process to block the corresponding spinal nerve.
How does spread differ in 2 regions
how does this affect reliablity when multi level reqd
In the thoracic region,
a single large-volume injection may spread
cephalad or caudad to reach
one or more spinal nerves.
No such communications exist between
different levels in lumbar region.
Therefore, multiple injections are needed.
However, when a reliable multiple-level anaesthesia is desired, multiple small-volume injections
are preferred over a single large-volume injection.
This may slightly
increase the chances of pneumothorax.
PVB indications
Indications for PVB are breast surgery, thoracotomy, cholecystectomy, renal and ureteric surgery, inguinal hernia, appendicectomy, video assisted thoracic surgery and minimally invasive cardiac surgery.
It may be used to provide analgesia for
fractured ribs, flail chest and
herpes zoster neuralgia.
How can PVB be perfomred
Catheter thread
PVB can be performed using a landmark,
nerve stimulator or an
ultrasound-based technique.
It is also suited for catheter techniques.
However, unlike the epidural space, catheter advancement in the
paravertebral space is met with significant resistance.
If a catheter
threads ‘easily’, one should be concerned that the needle has entered the thorax.
Complications
PVB
Complications may include ipsilateral epidural spread (up to 70%), contralateral epidural spread (7%), intravascular injections, subarachnoid injections, haematoma formation,
pneumothorax (0.5%),
Air aspiration during needle insertion may indicate lung
puncture.
hypotension
and
systemic toxicity.
Post-dural punture headache has
been reported.
PVB
medial angulation
lateral angulation
Medial angulation of the needle increase chances of
epidural/subarachnoid spread, but lateral angulation may increase
chances of pneumothorax.
Intravenous regional anaesthesia (IVRA),
Intro by
August Bier was the first to
introduce intravenous regional
anaesthesia (IVRA, also called the Bier block), in 1908
IVRA LA used
Where used
duration
kids?
Lignocaine and procaine are the most commonly employed local anaesthetics.
IVRA is appropriate for surgeries and manipulations of the extremities requiring anaesthesia for up to an hour. It has been successfully used
in the paediatric population as well.
Upper or lower easier?
The block is easier to perform in upper extremity than the lower; with
the latter needing larger volumes of LA and higher occlusion pressures for an adequate block.
Absolute contraindications
relative
Although the block is relatively contraindicated in crush injuries,
compound fractures, peripheral vascular disease and sickle-cell disease,
the only absolute contraindication is patient refusal
IVRA and acoag?
Bier block is an acceptable form of regional anaesthesia in
anticoagulated patients.
Other uses IVRA
IVRA has been also used for treatment of complex regional pain
syndrome (CRPS) (guanethidine) and hyperhydrosis (botulinum toxin).
The correct sequence of events for IVRA
The correct sequence of events for IVRA is:
intravenous cannulation,
exsanguination,
proximal cuff inflation,
LA injection,
distal cuff inflation,
proximal cuff deflation.
IVRA
LA to avoid
Bupivacaine should be avoided because of its cardiotoxicity.
IVRA
Any vein?
injection speed?
Although any vein may be cannulated, fast injections through antecubital veins may lead to escape of LA under the cuff.
Injections should be made slowly (over 90 seconds) to produce a peak venous pressure that is not greater than the occluding pressure of the cuff.
IVRA Cuff deflation
Cuff should not be deflated
before 20 minutes.
If less than 45 minutes have passed,
the cuff is deflated in a two-stage release,
first deflated for 10 seconds and
then reinflated for a minute before release.
After 45 minutes, the risk of systemic toxicity is minimal.
IVRA Additives
what has best evidence
Although opioids, α2 agonists (clonidine and dexmetomidine), muscle relaxants, dexamethasone and neostigmine have all shown some promise,
only non-steroidal anti-inflammatory drugs (ketorolac) have shown good evidence as adjuncts in systemic review
IVRA dose
UL
LL
Dosages:
Upper limb: 0.5% lignocaine
30–50 mL or 2% lignocaine 12–15 mL.
Lower limb: 0.5% lignocaine 50–100 mL or 2% lignocaine 15–30 mL
± ketorolac 20 mg.
