Dr Amit Pawa - concepts in Fascial Plane Blocks

Fascial Plane Blocks -
Current Concepts
@amit_pawa

Disclosures
RA-UK President
GE Healthcare - Credit for filmed scanning videos
Sintetica Ltd
B Braun Medical Ltd
@amit_pawa
and...
Butterfly Network, Inc
Pacira

I Have Contributed…
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In the next 30 mins…
Some Concepts
Some Evidence
My Opinions
Some Scanning
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This might be a
bit controversial
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“Fascial Plane Blocks” are a
Heterogenous Group of
Techiques
1.
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Fascial Plane Blocks
mechanism/s of action
are unknown
2.
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Fascial Plane Blocks are not
always predictable
3.
@amit_pawa

may have a role in
the absence of
Epidural/PVB
4.
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increase delivery of RA
5.
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For Successful RA
Right Dose
Drug
Place
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Right
Right

For Plexus/Peripheral RA
Nerve

How do we find nerves?
@amit_pawa

Landmark-Guided Blocks
PNS-Guided Blocks
US-Guided Blocks

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Are we getting Too close?

With (Fascial) Plane Blocks…
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We Don’t Need to See Our Target
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Gone too Far?

TAP
QLB 1/2/3
Femoral Triangle Block
PECS 1/11 Serratus
RISS
TQL
ESP BD-TAP
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RLB
MTP SSPS
PSPS
Shamrock
Lumbar Plexus
SPEDI
Clavipectoral
iPack
PENG
ACB
MICB
TTP
PIFB

TAP
QLB 1/2/3
Femoral Triangle Block
PECS 1/11 Serratus
RISS
TQL
ESP BD-TAP
@amit_pawa
RLB
MTP SSPS
PSPS
Shamrock
Lumbar Plexus
SPEDI
Clavipectoral
iPack
PENG
ACB
MICB
TTP
PIFB
Heterogenous group!

@amit_pawa
Too many blocks!
Inconsistent NOMENCLATURE
Watch this space - being addressed

Important References
@amit_pawa

Soft Collagen-Containing
Loose & Dense Fibrous Connective Tissue
Permeates Whole Body
Skin
Superficial fascia
Deep Fascia
(multilayer)
Muscle & related fascia
Superficial adipose tissue
Deep adipose tissue
Loose connective tissue
What is Fascia?
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Deep Fascia
Multiple layers, Fibrous
Extends through whole body
Target for Fascial plane blocks
Forms sheaths for nerves/vessels/organs
@amit_pawa

Deep Fascia Subtypes
Epimysial Aponeurotic
Thin Thick
Specific to 1 muscle May cover several muscles
Adherent to muscle Easily separated
PECS/TAP/Serratus Rectus Sheath/Adductor Canal

Lines of Fusion
Distinct fusion points
e.g. Linea Alba/Semilunaris
Creates a “compartment”
(Pathological LOF due to surgery/Adhesions)
Limit Spread - Good (rectus) & Bad!
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Fascial Interconnectivity
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Fascial Interconnectivity
Connections between fascia
Many Planes are continuous
Communicate without clear boundaries
Thoracolumbar Fascia
Endothoracic Fascia
Gluteal Fascia
May help Mechanism of Action
@amit_pawa

Not All fascias are the same
Number of layers
Pectoral region - 1
The Limbs - 2 or 3
Middle Thoracolumbar 2 or 3
Function & Mobility More mobile may
increase LA spread
Surrounding structures
Lungs/liver/spleen
IPPV vs SV
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Mechanism of Action?
LA action on:
Nerves in the injected Plane
Nerves in adjacent Planes/tissue
Nerves in distant Planes/tissue
(Systemic Absorption)
Mechanisms of Action Of Fascial Plane Blocks - Jinn KJ, Lirk P, Hollmann M, Schwarz S - Ahead of Print RAPM 2021
@amit_pawa

What Nerves might the LA act on?
Cutaneous
Lat. cut. intercostal branches
(Serratus Plane)
Non-Cutaneous - usually silent Nociceptors
Muscle/Ligaments/Joint capsules/Bone/others in fascia
Upregulated in inflammation /injury
Motor Nerves
Some fibres still sensory/nociceptive
Blockade relieves spasm
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@amit_pawa

@amit_pawa
Hydrodissection via Hydraulic Pressure
“Transmission Belts” & “Decompression planes”
Eg Rectus Sheath, TAP, PECS

Plane 1.
Plane 2.
Nerves in Adjacent Planes/Tissue
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Plane 1.
Plane 2.
Bulk Flow
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Plane 1.
Plane 2.
Bulk Flow
E.g. PECS, ESP, MTP
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Diffusion
concentration gradient

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Nerves at Distant
Sites via
Systemic Absorption
pleura
mus
mus
ESM
ostal nerve
or cutaneous branch of intercostal nerve
Transversus thoracis muscle
ectoral nerves
RLB
ESP TPVB
MTP
acromial artery
Rhomboid
d
Block

“Back-Door” ?
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“by-proxy”

Biomechanical properties
@amit_pawa
Fascia Is Dynamic

Biomechanical properties
Pumping mechanism due to muscle tendons?
Contractile elements within fascia?
-> Variable/extensive dermatomal spread?
Effect of:
Depth of Anaesthesia & Muscle Relaxation?
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Supra inguinal FIB
Volunteer Study
Passive Muscle movement
altered LA distribution
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(a)
(b)
Anaesthesia, 2011, 66, pages 1023–1030
..............................................................................................
rsal extension with an anterior subcostal
ock. (b) Bilateral mid-axillary ultra-
(b)
Figure 8 (a) Bilateral ultrasound via the posterior approac
showing extension along the quadratus lumborum muscle
ORIGINAL ARTICLE
Studies on the spread of local anaesthetic solution in
transversus abdominis plane blocks*
J. Carney,1
O. Finnerty,1
J. Rauf,1
D. Bergin,4
J. G. Laffey2
and J. G. Mc Donnell3
1 Registrar, 2 Professor, 3 Senior Clinical Lecturer, Department of Anaesthesia and Intensive Care Medicine,
4 Senior Clinical Lecturer, Department of Radiology, Galway University Hospitals, Galway, Ireland
Summary
The extent of analgesia provided by transversus abdominis plane blocks depends upon the site of
injection and pattern of spread within the plane. There are currently a number of ultrasound-
guided approaches in use, including an anterior oblique-subcostal approach, a mid-axillary
approach and a more recently proposed posterior approach. We wished to determine whether the
site of injection of local anaesthetic into the transversus abdominis plane affects the spread of the
local anaesthetic within that plane, by studying the spread of a local anaesthetic and contrast
solution in four groups of volunteers. The first group underwent the classical landmark-based
transversus abdominis plane block whereby two different volumes of injectate were studied:
0.3 ml.kg)1
vs 0.6 ml.kg)1
. The second group underwent transversus abdominis plane block using
the anterior subcostal approach. The third group underwent transversus abdominis plane block
using the mid-axillary approach. The fourth group underwent transversus abdominis plane block
using the posterior approach, in which local anaesthetic was deposited close to the antero-lateral
border of the quadratus lumborum. All volunteers subsequently underwent magnetic resonance
imaging at 1, 2 and 4 h following each block to determine the spread of local anaesthetic over time.
The studies demonstrated that the anterior subcostal and mid-axillary ultrasound approaches res-
ulted in a predominantly anterior spread of the contrast solution within the transversus abdominis
plane and relatively little posterior spread. There was no spread to the paravertebral space with the
anterior subcostal approach. The mid-axillary transversus abdominis plane block gave faint contrast
ORIGINAL ARTIC
Studies on the sp
transversus abdom
1 1
Anaesthesia, 2011, 66, pages 1023–1030
..............................................................
US- Guided Posterior TAP spreads to PVS
@amit_pawa

Injectate Spread With the TQL Block
Figure 3. Pathway. A, Visualization of spread of
dye posterior to the transversalis fascia from the
lumbar position and into the thoracic paraverte-
bral space. The 2 tweezers are placed posterior
to both arcuate ligaments. The dye spreads pos-
terior to the medial and lateral arcuate ligaments
(blue circle). The Magenta dotted line indicates
diaphragm. B, Red arrow: Green dye is visualized
posterior to endothoracic fascia within the tho-
racic cage. The magenta dotted line indicates the
diaphragm; PM, psoas major.
BACKGROUND: The spread of injectate resulting from a transmuscular quadratus lumborum
(TQL) block and a transverse oblique paramedian (TOP) TQL block has never been examined.
The aim of this cadaveric study was to investigate by which pathway the injectate spreads
cephalad into the thoracic paravertebral space and which nerves were dyed by the injectate
cephalad and caudad to the diaphragm when performing a TQL and a TOP TQL block. We also
aimed to investigate whether the thoracic and lumbar sympathetic trunks as well as the lumbar
plexus were covered by the injectate.
METHODS: Ultrasound-guided bilateral TQL and TOP TQL injections were administered in 8
cadavers. A total of 16 injections were performed. With the TQL injection, the curvilinear trans-
ducer was oriented in the transverse plane above the iliac crest at the posterior axillary line to
identify the Shamrock sign. With the TOP TQL injection, the same transducer was placed with
a TOP orientation 3 cm lateral to the L2 spinous process to identify the L2 transverse process
and the adjoining quadratus lumborum muscle. For both techniques, the needle was advanced
in-plane to the transducer, with the end point in the interfascial plane between the quadratus
lumborum and psoas major muscles. Thirty milliliters of dye solution was injected bilaterally for
each technique. The spread of the dye was evaluated by subsequent dissection.
RESULTS: In all successful injections, the dye was seen to spread into the thoracic paravertebral
space and the intercostal spaces to surround the somatic nerves and the thoracic sympathetic
trunk. The main pathway of spread of injectate was posterior to the medial and lateral arcuate liga-
ments. Caudad to the diaphragm, the injected dye surrounded the subcostal, iliohypogastric, and
ilioinguinal nerves in all cases, whereas the genitofemoral and lateral femoral cutaneous nerves
were dyed in a varying degree. No dye was seen to surround the lumbar plexus, femoral nerve, or
lumbar sympathetic trunk. The pattern of spread was similar with the TQL and TOP TQL injections.
CONCLUSIONS: The spread of injectate with the TQL and TOP TQL approaches is cephalad
from the lumbar point of administration between the quadratus lumborum and psoas major
muscles, predominantly via a pathway posterior to the arcuate ligaments and into the thoracic
paravertebral space to reach the somatic nerves and the thoracic sympathetic trunk in the
intercostal and paravertebral spaces. The lumbar plexus and lumbar sympathetic trunk are not
affected. (Anesth Analg 2017;125:303–12)
The Pathway of Injectate Spread With the
Transmuscular Quadratus Lumborum
Block: A Cadaver Study
Mette Dam, MD,* Bernhard Moriggl, MD, PhD,† Christian K. Hansen, MD,* Romed Hoermann,†
Thomas F. Bendtsen, MD, PhD,‡ and Jens Børglum, MD, PhD*
CHRONIC PAIN MEDICINEORIGIN
Section Editor: Honorio T. Benzon
Copyright © 2017 International Anesthe
July 2017 • Volume 125 • Number 1
nesthesia Research Society. Unauthorized reproduction of this article is prohibited.
a.org ANESTHESIA & ANALGESIA
TQL spreads to PVS & Sympathetic trunk
Lumbar plexus was not stained
@amit_pawa
T10. As with the TQL approach, the ventral rami of the spi-
nal nerves were dyed as proximal as the cranial distribution
of dye spread. The thoracic sympathetic trunk was dyed in
100% (CI, 0.39–1.00) of the cases.
Caudad to the diaphragm, the subcostal, iliohypogastric,
and ilioinguinal nerves were dyed in 100% (CI, 0.39–1.00)
of the cases, whereas the genitofemoral and lateral femoral
cutaneous nerves were dyed to a varying degree (Table 2).
The lumbar plexus was never dyed within the psoas major
muscle; nor was the femoral nerve or the lumbar sympa-
thetic trunk. In addition, no dye was detected intraperito-
neally, and there was no dye observed spreading into the
transversus abdominis plane.
evaluate the
QLB.1,4,18,20
The main
dye to the t
posterior to
the majority
was posteri
phragmatic
to be able to
The vent
nerves) wer
the dorsal ra
dye reachin

mixture comprising 10 mL of an iodinated
hexol (Omnipaque 300; GE Healthcare,
), diluted in 85 mL of 0.9% sodium chloride
collimation, 1.2 mm. Images were reconstructed using a soft
tissue algorithm at 3 mm slice thickness at 3-mm intervals. All
images were reviewed by a consultant radiologist. Spread of
nsional CT reconstruction of injectate spread (darker area) after injection at the T5 level deep to erector spinae muscle.
caudal spread from T1 to T8. The solid arrows indicate the penetration of dye beyond the costotransverse junction
intertransverse spaces.
d Pain Medicine • Volume 41, Number 5, September-October 2016 ESP Block in Thoracic Pain
Twenty milliliters of a mixture comprising 10 mL of an iodinated
contrast material, iohexol (Omnipaque 300; GE Healthcare,
Princeton, New Jersey), diluted in 85 mL of 0.9% sodium chloride
with 5 mL of methylene blue dye was injected. Within 20 minutes
of completing the injections, cadaver 2 was transferred to a 128-slice
multidetector CT scanner (Siemens Flash CT; Siemens Healthcare)
where abdominal and thoracic imaging was performed to radio-
graphically assess the distribution of injectate. Images were
acquired using routine clinical imaging protocols with the follow-
ing parameters: kilovolt (peak), 120; effective milliampere-
second, 210; rotation time, 0.5 seconds; pitch, 0.8; and detector
collimation, 1.2 mm. Images were recon
tissue algorithm at 3 mm slice thickness
images were reviewed by a consultant r
injectate was assessed primarily upon rev
set supplemented with multiplanar images
caudal spread of injectate from C7 to T8
T8 on the left, occurring in a paraspinous
transverse processes anteriorly and the erec
teriorly (Fig. 5). Lateral spread extended t
verse processes at all levels, and slightly bey
junctions at levels T3 to T6 on the right an
FIGURE 6. Dissection of the right side of cadaver 2 after an ultrasound-guided ESP block and dye injection deep to e
Trapezius and rhomboid muscles have been removed. The longissimus thoracis portion of the erector spinae muscle
cranially and dense staining of its anterior (deep) surface is visible. The external intercostal muscle, internal intercosta
surrounding tissues are also heavily stained. Dye has penetrated deep to these layers and through the costotransvers
The Erector Spinae Plane Block
A Novel Analgesic Technique in Thoracic Neuropathic Pain
Mauricio Forero, MD, FIPP
,* Sanjib D. Adhikary, MD,† Hector Lopez, MD,‡
Calvin Tsui, BMSc,§ and Ki Jinn Chin, MBBS (Hons), MMed, FRCPC||
oracic neuropathic pain is a debilitating condition that is
sponsive to oral and topical pharmacotherapy. The benefit
al nerve block procedures is unclear due to a paucity of ev-
invasiveness of the described techniques. In this report, we
el interfascial plane block, the erector spinae plane (ESP)
uccessful application in 2 cases of severe neuropathic pain
ng from metastatic disease of the ribs, and the second from
ultiple rib fractures). In both cases, the ESP block also pro-
sive multidermatomal sensory block. Anatomical and radio-
ation in fresh cadavers indicates that its likely site of action
and ventral rami of the thoracic spinal nerves. The ESP
omise as a simple and safe technique for thoracic analgesia
neuropathic pain as well as acute postsurgical or posttrau-
in Med 2016;41: 00–00)
hic pain is a common chronic pain condition with
tiologies, including surgery, trauma, and diseases
s zoster, diabetes, and cancer.1
It is notoriously diffi-
Case 1
A 67-year-old man, weight 116 kg and height 188 cm [body
mass index (BMI), 32.8 kg/m2
] with a history of heavy smoking
and paroxysmal supraventricular tachycardia controlled on ateno-
lol, was referred to the chronic pain clinic with a 4-month history
of severe left-sided chest pain. A magnetic resonance imaging
scan of his thorax at initial presentation had been reported as nor-
mal, and the working diagnosis at the time of referral was post-
herpetic neuralgia. He reported constant burning and stabbing
neuropathic pain of 10/10 severity on the numerical rating score
(NRS), radiating from his spine into the anterior chest wall, mainly
at T5 and extending several dermatomes inferiorly. There was sig-
nificant sleep disturbance and impairment of quality of life. Phys-
ical examination revealed allodynia and hyperesthesia over the
affected dermatomes with a primary trigger point over the T5 der-
matome 3 to 4 cm lateral to the neuraxial midline. Pain manage-
ment up to that point had included pregabalin (600 mg daily at
the time of consultation), nonsteroidal anti-inflammatory drugs,
baclofen, fluoxetine, and marijuana with no improvement. Several
different opioids had been tried but all had to be stopped due to
Within several minutes, the patient reporte
diminished significantly, and a full assessment
sensory block was performed 2 hours later. By
tient had obtained complete relief of pain, with
There was an area of diminished sensation to p
Hospital, McL 2-405, 399 Bathurst St, Toronto, Ontario, Canada M5T 2S8
(e‐mail: gasgenie@gmail.com).
The authors declare no conflict of interest.
Copyright © 2016 by American Society of Regional Anesthesia and Pain
Medicine
ISSN: 1098-7339
DOI: 10.1097/AAP.0000000000000451
Regional Anesthesia and Pain Medicine • Volume 41, Number 5, September-October 2016
Copyright © 2016 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this a
ESP injection travels up & down & spreads to PVS
@amit_pawa

ESP Mechanism?
PVB spread by Proxy?
jected dyes into the back muscles after retrolaminar (RL, right) and ESP block (ESP, left).
columbar fascia covering the erector spinae muscle was revealed. (b) The muscle ﬁbre
The spread pattern of the dyes in the vertebral laminae was seen after removal of all bac
ocostalis; Lo, longissimus thoracis).
(b)
(c)
Anaesthesia 2018, 73, 1244–1250
Original Article
Comparison of injectate spread and nerve involvement
between retrolaminar and erector spinae plane blocks in
the thoracic region: a cadaveric study
H.-M. Yang,1
Y. J. Choi,2
H.-J. Kwon,3
J. O,3
T. H. Cho3
and S. H. Kim4
1 Assistant Professor, 2 Instructor, 3 Research Assistant, Department of Anatomy, 4 Associate Professor, Department of
Anaesthesiology and Pain Medicine, Anaesthesia and Pain Research Institute, Yonsei University College of Medicine,
Seoul, Korea
Summary
Although different injection locations for retrolaminar and erector spinae plane blocks have been described,
the two procedures have a similar anatomical basis. In this cadaveric study we compared anatomical spread of
dye in the thoracic region following these two procedures. Following randomisation, 10 retrolaminar blocks
and 10 erector spinae plane blocks were performed on the left or right sides of 10 unembalmed cadavers. For
each block, 20 ml of dye solution was injected at the T5 level. The back regions were dissected and the
involvement of the thoracic spinal nerve was also investigated. Twenty blocks were successfully completed. A
consistent vertical spread, with deep staining between the posterior surface of the vertebral laminae and the
overlaying transversospinalis muscle was observed in all retrolaminar blocks. Moreover, most retrolaminar
blocks were predominantly associated with fascial spreading in the intrinsic back muscles. With an erector
spinae plane block, dye spread in a more lateral pattern than with retrolaminar block, and fascial spreading in
the back muscles was also observed. The number of stained thoracic spinal nerves was greater with erector
spinae plane blocks than with retrolaminar blocks; median 2.0 and 3.5, respectively. Regardless of technique,
the main route of dye spread was through the superior costotransverse ligament to the ipsilateral paravertebral
space. Although erector spinae plane blocks were associated with a slightly larger number of stained thoracic
spinal nerves than retrolaminar blocks, both techniques were consistently associated with posterior spread of
Anaesthesia 2018 doi:10.1111/anae.14408
Original Article
Comparison of injectate spread and ner
between retrolaminar and erector spina
H.-M. Yang,1
Y. J. Choi,2
H.-J. Kwon,3
J. O,3
T. H. Cho3
and S. H
Anaesthesia 2018, 73, 1244–1250
@amit_pawa

ESP Mechanism?
PVB spread by Proxy?
jected dyes into the back muscles after retrolaminar (RL, right) and ESP block (ESP, left).
columbar fascia covering the erector spinae muscle was revealed. (b) The muscle ﬁbre
The spread pattern of the dyes in the vertebral laminae was seen after removal of all bac
ocostalis; Lo, longissimus thoracis).
(b)
(c)
Anaesthesia 2018, 73, 1244–1250
Original Article
Comparison of injectate spread and nerve involvement
between retrolaminar and erector spinae plane blocks in
H.-M. Yang,1
Y. J. Choi,2
H.-J. Kwon,3
J. O,3
T. H. Cho3
and S. H. Kim4
1 Assistant Professor, 2 Instructor, 3 Research Assistant, Department of Anatomy, 4 Associate Professor, Department of
Anaesthesiology and Pain Medicine, Anaesthesia and Pain Research Institute, Yonsei University College of Medicine,
Seoul, Korea
Summary
Although different injection locations for retrolaminar and erector spinae plane blocks have been described,
the two procedures have a similar anatomical basis. In this cadaveric study we compared anatomical spread of
dye in the thoracic region following these two procedures. Following randomisation, 10 retrolaminar blocks
and 10 erector spinae plane blocks were performed on the left or right sides of 10 unembalmed cadavers. For
each block, 20 ml of dye solution was injected at the T5 level. The back regions were dissected and the
involvement of the thoracic spinal nerve was also investigated. Twenty blocks were successfully completed. A
consistent vertical spread, with deep staining between the posterior surface of the vertebral laminae and the
overlaying transversospinalis muscle was observed in all retrolaminar blocks. Moreover, most retrolaminar
blocks were predominantly associated with fascial spreading in the intrinsic back muscles. With an erector
spinae plane block, dye spread in a more lateral pattern than with retrolaminar block, and fascial spreading in
the back muscles was also observed. The number of stained thoracic spinal nerves was greater with erector
spinae plane blocks than with retrolaminar blocks; median 2.0 and 3.5, respectively. Regardless of technique,
the main route of dye spread was through the superior costotransverse ligament to the ipsilateral paravertebral
space. Although erector spinae plane blocks were associated with a slightly larger number of stained thoracic
spinal nerves than retrolaminar blocks, both techniques were consistently associated with posterior spread of
Anaesthesia 2018 doi:10.1111/anae.14408
Original Article
Comparison of injectate spread and ner
between retrolaminar and erector spina
H.-M. Yang,1
Y. J. Choi,2
H.-J. Kwon,3
J. O,3
T. H. Cho3
and S. H
Anaesthesia 2018, 73, 1244–1250
“the amount of dye within the paravertebral space following both
retrolaminar and ESP injections seemed to be too small to allow for upward
or downward flow.”
@amit_pawa

Dorsal Rami Spread only?
ESP Mechanism?
A Cadaveric Study Investigating the Mechanism of Action
of Erector Spinae Blockade
Jason Ivanusic, PhD,* Yasutaka Konishi, MD,†‡ and Michael J. Barrington, PhD, MBBS, FANZCA†§
Background and Objectives: Erector spinae block is an ultrasound-
guided interfascial plane block first described in 2016. The objectives of
this cadaveric dye injection and dissection study were to simulate an erector
spinae block to determine if dye would spread anteriorly to the involve or-
igins of the ventral and dorsal branches of the spinal nerves.
Methods: In 10 unembalmed human cadavers, 20 mL of 0.25% methy-
lene blue dye was injected bilaterally into the plane between the fifth thoracic
transverse process and erector spinae muscle. An in-plane ultrasound-guided
technique with the transducer orientated longitudinally was used. During
dissection, superficial and deep muscles were identified, and extent of
dye spread was documented in cephalocaudal and lateral directions. The
ventral and dorsal rami of spinal nerves and dorsal root ganglion at each
level were examined to determine if they were stained by dye.
Results: There was extensive cephalocaudad and lateral spread of dye
deep and superficial to the erector spinae muscles. Except for 1 injection
(from 20), the ventral rami were not stained by the dye. In only 2 injections
did the dye track posteriorly through the costotransverse foramen to the
dorsal root ganglion. In all other cases, the dorsal root ganglia were not in-
volved in the dye injection. The dye stained the dorsal rami posterior to the
costotransverse foramen.
Conclusions: There was no spread of dye anteriorly to the paravertebral
space to involve origins of the ventral and dorsal branches of the thoracic spinal
nerves. Dorsal ramus involvement was posterior to the costotransverse foramen.
(Reg Anesth Pain Med 2018;43: 567–571)
In clinical reports, ESB resulted in extensive cutaneous sen-
sory block indicating both ventral and dorsal spinal rami involve-
ment.1
Furthermore, a cadaveric dye injection and dissection in 1
cadaver reported spread of dye in the vicinity of the origins of the
ventral and dorsal rami of the spinal nerves.1
Hence, ESB has
been described as a technically simpler alternative to ultrasound-
guided paravertebral block with a similar mechanism of action.
In addition, ESB is likely to be safer than paravertebral blockade
because the injection is in a plane remote from critical structures
such as the pleura, and thus there has been significant clinical in-
terest in this block. Therefore, the objective of this current cadav-
eric experiment was to simulate an ESB to determine if dye would
spread anteriorly to the paravertebral space to involve the origins
of the ventral and dorsal branches of the thoracic spinal nerves.
The extents of craniocaudal and medial-to-lateral spread of the
dye were also documented.
METHODS
This project was approved by the Human Research Ethics
Committee, University of Melbourne (Project within Program
Ethics ID 1441811.3). Ten unembalmed human cadavers were ob-
tained through the body donor program of the Department of
Anatomy and Neuroscience. None of the specimens were frozen
before the interventions were performed. Before commencement
REGIONAL ANESTHESIA AND ACUTE PAIN
ORIGINAL ARTICLE
tion. A skin incision was made along the midlin
processes from above C7 to the lower lumbar ver
reflected laterally to expose the posterior thoracic
Superficial muscles (trapezius, latissimus dorsi
were individually identified and reflected. T
muscles were identified and removed at their
the extent of dye spread deep and superficial t
explored and documented. The extent of cepha
(e‐mail: Michael.Barrington@svha.org.au).
Funding was from departmental resources only. Support was provided by the
Imaging and Posters Unit at the Department of Anatomy and Neuroscience,
University of Melbourne, and Anastasia Arsenoulis from FUJIFILM
SonoSite, Inc, which provided an ultrasound machine.
Medicine
ISSN: 1098-7339
DOI: 10.1097/AAP.0000000000000789
Regional Anesthesia and Pain Medicine • Volume 43, Number 6, August 2018
@amit_pawa

Dorsal Rami Spread only?
ESP Mechanism?
A Cadaveric Study Investigating the Mechanism of Action
of Erector Spinae Blockade
Jason Ivanusic, PhD,* Yasutaka Konishi, MD,†‡ and Michael J. Barrington, PhD, MBBS, FANZCA†§
Background and Objectives: Erector spinae block is an ultrasound-
guided interfascial plane block first described in 2016. The objectives of
this cadaveric dye injection and dissection study were to simulate an erector
spinae block to determine if dye would spread anteriorly to the involve or-
igins of the ventral and dorsal branches of the spinal nerves.
Methods: In 10 unembalmed human cadavers, 20 mL of 0.25% methy-
lene blue dye was injected bilaterally into the plane between the fifth thoracic
transverse process and erector spinae muscle. An in-plane ultrasound-guided
technique with the transducer orientated longitudinally was used. During
dissection, superficial and deep muscles were identified, and extent of
dye spread was documented in cephalocaudal and lateral directions. The
ventral and dorsal rami of spinal nerves and dorsal root ganglion at each
level were examined to determine if they were stained by dye.
Results: There was extensive cephalocaudad and lateral spread of dye
deep and superficial to the erector spinae muscles. Except for 1 injection
(from 20), the ventral rami were not stained by the dye. In only 2 injections
did the dye track posteriorly through the costotransverse foramen to the
dorsal root ganglion. In all other cases, the dorsal root ganglia were not in-
volved in the dye injection. The dye stained the dorsal rami posterior to the
costotransverse foramen.
Conclusions: There was no spread of dye anteriorly to the paravertebral
space to involve origins of the ventral and dorsal branches of the thoracic spinal
nerves. Dorsal ramus involvement was posterior to the costotransverse foramen.
(Reg Anesth Pain Med 2018;43: 567–571)
In clinical reports, ESB resulted in extensive cutaneous sen-
sory block indicating both ventral and dorsal spinal rami involve-
ment.1
Furthermore, a cadaveric dye injection and dissection in 1
cadaver reported spread of dye in the vicinity of the origins of the
ventral and dorsal rami of the spinal nerves.1
Hence, ESB has
been described as a technically simpler alternative to ultrasound-
guided paravertebral block with a similar mechanism of action.
In addition, ESB is likely to be safer than paravertebral blockade
because the injection is in a plane remote from critical structures
such as the pleura, and thus there has been significant clinical in-
terest in this block. Therefore, the objective of this current cadav-
eric experiment was to simulate an ESB to determine if dye would
spread anteriorly to the paravertebral space to involve the origins
of the ventral and dorsal branches of the thoracic spinal nerves.
The extents of craniocaudal and medial-to-lateral spread of the
dye were also documented.
METHODS
This project was approved by the Human Research Ethics
Committee, University of Melbourne (Project within Program
Ethics ID 1441811.3). Ten unembalmed human cadavers were ob-
tained through the body donor program of the Department of
Anatomy and Neuroscience. None of the specimens were frozen
before the interventions were performed. Before commencement
REGIONAL ANESTHESIA AND ACUTE PAIN
ORIGINAL ARTICLE
tion. A skin incision was made along the midlin
processes from above C7 to the lower lumbar ver
reflected laterally to expose the posterior thoracic
Superficial muscles (trapezius, latissimus dorsi
were individually identified and reflected. T
muscles were identified and removed at their
the extent of dye spread deep and superficial t
explored and documented. The extent of cepha
(e‐mail: Michael.Barrington@svha.org.au).
Funding was from departmental resources only. Support was provided by the
Imaging and Posters Unit at the Department of Anatomy and Neuroscience,
University of Melbourne, and Anastasia Arsenoulis from FUJIFILM
SonoSite, Inc, which provided an ultrasound machine.
Medicine
ISSN: 1098-7339
DOI: 10.1097/AAP.0000000000000789
Regional Anesthesia and Pain Medicine • Volume 43, Number 6, August 2018
nusic et al Regional Anesthesia and Pain Medicine • Volume 43, Number 6, August 2018
@amit_pawa

What can we say about ESP?
@amit_pawa
PVS VR DR

What can we say about ESP?
There is limited evidence of “By-Proxy” spread
Variation exists in Cadaver studies too!
Cadaver results may not relate to “Real Life”
(Mechanical Ventilation/Movement)
@amit_pawa

Fascial Plane Blocks can be
Unpredictable
Inconsistent Effect
Inconsistent Efficacy
Inconsistent Evidence
Dense Neural Blockade is Rare
@amit_pawa

LA Spread Affected by…
Thickness of fascia
Thick fascia - easy to identify, limited diffusion,
“contains LA”, but spread limited
Thin fascia - harder to identify, better diffusion,
LA “spills out” so spread variable
@amit_pawa

The Ideal Block
Credit: Dr Arun Venkataraju @amit_pawa

Is this good enough?
@amit_pawa
Less Ideal Blocks

Even when you get in the correct
plane - does the LA stay there?
Yang H, Kim SH Injectate spread in interfascial plane block: a microscopic finding
Regional Anesthesia & Pain Medicine Published Online First: 05 July 2019.
doi: 10.1136/rapm-2019-100693
@amit_pawa

Even when you get in the correct
plane - does the LA stay there?
Yang H, Kim SH Injectate spread in interfascial plane block: a microscopic finding
Regional Anesthesia & Pain Medicine Published Online First: 05 July 2019.
doi: 10.1136/rapm-2019-100693
“The Fascial plane is not a closed space”
"Injectate spread into the internal oblique &
transversus abdominus muscle via the Perimysium”
Could this affect the amount of LA
available to act?
@amit_pawa

Receptors within Fascia
Somatic Nerves (Sensory/Motor) - variable path
Sympathetic
Nerves to the Fascia - “Fasciatome”
Could action on last two subtypes
explain successful block without
dermatomal loss of sensation?

Does Inconsistent Dermatomal
sensory loss = Failed Block?
Analgesia & Opioid Reduction still evident
Differential block - (C >A-delta fibres)?
If pt derives benefit, does it matter?
PROM & Minimum Clinically Important Difference
(MCID) in QoR
@amit_pawa

Does Inconsistent Dermatomal
sensory loss = Failed Block?
Anatomical Cutaneous innervation is complex
Overlapping innervation across midline
Interindividual variation
Pharmacokinetic variability & concentration of LA at target
Accuracy of deposition & Variability of spread
Non-cutaneous contributions to nociception
@amit_pawa

How Can We Improve Efficacy?
Deposit LA closer to target- (e.g. Rectus > Lat TAP)
Inject at more than 1 site?
Increase Concentration of LA ?
Increase Mass of LA deposited ?
Use Epinephrine?
Catheters - Intermittent Boluses
@amit_pawa

PECS/Serratus/ESP -significant benefit in breast/thoracics
Similar to Th PVB (PECS)
Their role in trauma & cardiac surgery is holds great potential
@amit_pawa

Where May Fascial Plane
Blocks have a role?

If No Epidural/Spinal/PVB
Coagulation/Sepsis/Certain Specialties (Cardiac/Tx)
Hypotension (sympathectomy)/Side effects
Rescue technique (Failed Epidural/PVB)
Inability to perform Epidural/PVB
- Patient Positioning
- Lack of skilled practitioner/Post-op Monitoring
@amit_pawa

Paravertebral
PECS SERRATUS
ESP
Epidural
TAP
Rectus
ESP
SERRATUS
MTP
QLB
@amit_pawa

Increasing Access to RA
Much of USGRA - daunting to uninitiated
Idea of Fascial Plane Blocks is Simple
Superficial Planes - eg Rectus/PECS/TAP
Similar technique - Split the plane
Focus on “Plan A blocks” - Build from there
@amit_pawa

Promote competence
in a few HIGH V
ALUE
“Plan A” Blocks
Increase Patient
access to RA
Anatomical Location Plan A Block
Shoulder Interscalene
Upper limb below Shoulder Axillary
Hip Femoral Nerve
Knee Adductor Canal
Foot & Ankle Popliteal Sciatic
Chest Wall Erector Spinae Plane
Abdominal Midline Rectus Sheath
Endorsed
@amit_pawa

ESP
PVB
MTP
Skill Progression
@amit_pawa
Inspired by Ki Jinn Chin

ESP
PVB
MTP
Skill Progression
ESP
@amit_pawa

ESP
PVB
MTP
Skill Progression
ESP
MTP
@amit_pawa

ESP
PVB
MTP
Skill Progression
ESP
MTP
PVB
Risk Difficulty
@amit_pawa

Conclusions
@amit_pawa
1. Fascial Plane Blocks are Heterogenous
2. Unknown Mechanism of Action
3. Unpredictable efficacy
4. May have a role where No Epi/PVB
5. Increasing RA Delivery

Why We Need Fascial Plane Blocks In Our Toolkit
We need Alternatives when we can’t Perform classic
blocks, or when they fail
@amit_pawa
Regional Anaesthesia is part of MMA
We need to increase RA delivery so more patients
benefit
Some fascial plane blocks are simple to teach &
perform

Scanning
Videos courtesy of GE Healthcare

Dr Amit Pawa - concepts in Fascial Plane Blocks

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Dr Amit Pawa - concepts in Fascial Plane Blocks