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Updates on Brachial Plexus Block with or without Sonar guidance
E S S A Y
Submitted for Fulfillment of MSC Degree of Anaesthesiology
By
Marwan Mohamed Ahmed Foued
M.B.,B.Ch. (Cairo University)
Supervisors
Prof. Dr. Tarek Ahmed Mostafa Radwan
Professor of Anaesthesiology& Intensive CareFaculty of Medicine
Cairo University
Prof. Dr. Mohammad Yosry Mohammad Ahmad
Professor of Anaesthesiology& Intensive CareFaculty of Medicine
Cairo University
Dr. Ahmed Abd El-Aziz Arif
Assistant Professor of Anaesthesiology & Intensive CareFaculty of Medicine
Cairo University
Faculty of MedicineCairo University
2012
Key word
Brachial Plexus-Sonar guidance-CN XI-Brachial Plexus Block Approaches.
Abstract
Conventional brachial plexus block techniques are performed
without visual guidance and are highly dependent on surface anatomical
landmarks for localization of neural structures. It is, therefore, not
surprising that a reported failure rate of up to 20% occurs because of
incorrect needle and/or local anesthetic placement. Multiple trial and
error attempts at needle placement lead to operator frustration,
unwarranted patient pain and time delay in the operating room. Imaging
technology such as MRI and CT scan can successfully localize neural
structures. However, ultrasound is likely the most practical imaging tool
for assisting nerve blocks as it is portable, moderately priced and non-
invasive without radiation risk.
Acknowledgement
First thanks are all to "Allah" for blessing me this work until it reached its end, as a little part of his generom help thought life.
I would like to express my sincere appreciation and deep gratitude to Prof Dr. Tarek Ahmed Mostafa RadwanProfessor of anesthesiology and intensive care, Faculty of Medicine, Cairo University for his moral support, continuous encouragement, really it’s a great honor to work under his guidance and supervision.
It gives me a great pleasure to express my deepest gratitude to Prof Dr. Mohammad Yosry Mohammad Ahmad Professor of anesthesiology and intensive care, Faculty of Medicine, Cairo University for his kind advice, valuable supervision and his great efforts through this work.
I cannot forget to express my deepest thanks to Dr. Ahmed Abd El-Aziz Arif Assistant Professor of anesthesiology and intensive care, Faculty of Medicine, Cairo University for hiscontinuous encouragement, sincere help and endless cooperation.
Marwan Mohamed Ahmed Fouad
List of Contents
Pages
List of Abbreviations
List of Tables
List of Figures
I
II
III
Introduction …………………………………………………. 1
Review of Literature
Chapter (1)
Anatomy of Brachial Plexus …………………………………… 3
Chapter (2)
Basic Principles and Physics of Ultrasound …………………… 9
Chapter (3)
Patient Management …………………………………………… 15
Chapter (4)
Brachial Plexus Block Approaches …………………………...... 23
Chapter (5)
Approaches of Ultrasound Guided Brachial Plexus Block ……... 44
Summary ……………………………………………………… 60
References ……………………………………………………. 62
Arabic Summary …………………………………………….
I
List of Abbreviations
µg Microgram
AA Axillary Artery
ASM Anterior Scalene Muscle
AV Axillary Vein
c Speed of time
CA Carotid Artery
CN XI Cranial Nerve XI
D Depth
dB Decibel
DIC Disseminated Intravascular Coagulopathy
ƒ Frequency
FR First Rib
HZ Hertz
IJV Internal Jugular Vein
IP In Plane
IV Intravenous
mA milliAmpere
MHz Mega Hertz
MSM Middle Scalene Muscle
N Nerve
OOP Out Of Plane
OR Operating Room
PABA Para-Amino Benzoic Acid
PACU Post Anaesthesia Care Unit
PMiM Pectoralis Minor Muscle
PMM Pectoralis Major Muscle
SA Subclavian Artery
SCM Sternocleidomastoid Muscle
T Time
TP Transverse Process
λ Wavelength
II
List of Tables
Tables Pages
١ Interpreting Responses to Nerve Stimulation
(Interscalene block).
27
2 Complications of Interscalene block and How to Avoid
Them.
28
3 Interpreting responses to nerve stimulation
(Infraclavicular block).
37
4 Complications of Infraclavicular block and How to
Avoid Them.
38
5 Interpreting responses to nerve stimulation (Axillary
block).
42
6 Complications of Axillary block and how to avoid
them.
43
III
List of Figures
Figures Pages
١ Brachial plexus from roots to terminal divisions 4
2 Surface anatomy landmarks for Interscalene block. 23
3 Patient position and needle insertion for Interscalene
block.
24
4 The goal for Interscalene block. 26
5 Surface anatomy and landmarks for supraclavicular
block.
29
6 Surface anatomy landmarks for Infraclavicular block. 33
7 The site of needle insertion for Infraclavicular block. 35
8 The goal for Infraclavicular block. 36
9 Surface anatomy landmarks and position of the patient
for Axillary block.
39
10 The site of needle insertion for Axillary block. 40
11 The site of needle insertion for Musculocutaneous
Nerve Block.
41
12 Probe position for the interscalene brachial plexus. 44
13 Ultrasonic image of brachial plexus in interscalene
groove.
45
14 Ultrasonic scanning of interscalene groove (cephalic). 46
15 Ultrasonic scanning of interscalene groove (caudal). 47
16 Probe position for the supraclavicular brachial plexus
block.
49
17 Ultrasonic image of brachial plexus in supraclavicular
region.
50
IV
List of Figures (Cont.)
Figures Pages
18 Image of needle in contact with brachial plexus in
supraclavicular region.
51
19 Probe position for the Infraclavicular brachial plexus
block.
52
20 Ultrasonic image of brachial plexus in Infraclavicular
region.
53
21 Needle in contact with the posterior cord behind the
axillary artery.
55
22 Probe position for the Axillary brachial plexus block. 56
23 Transverse Sonogram in Axillary region. 57
24 Ultrasonographic findings of variation in nerve
location around the Axillary artery
58
- 1 -
Introduction
Introduction
Peripheral nerve blocks play an important role in modern regional
anaesthesia and pain medicine. The concept of direct visualization of
nerve structures via ultrasonography is convincing and supported by
recent publications.[1]
Advocates of use of ultrasound believe that the use of ultrasound
technology provides a superior technique by allowing visualization of the
target structure (i.e. the nerve) and other structures of interest (i.e. blood
vessels, lung, pleura,…), a real time examination of the spread of local
anaethetic as it is injected, and the ability of reposition of the needle to
both avoid injury and increase success rates.[2]
Ultrasonographic guidance for peripheral nerve blocks offers
significant advantages compared with conventional methods such as
peripheral nerve stimulation and nerve mapping. It shortens sensory onset
times, improves the quality and the duration of blocks, may avoid
complications such as intraneuronal punctures, inadvertent vessel
punctures and pneumothorax during periclavicular brachial plexus blocks,
and enables a reduction of the volume of local anaesthetic due to precise
administration of the local anaesthetic solution.[3]
Ultrasound guidance may eliminate the need for electrical
stimulation and therefore reduce pain of the block. This was confirmed by
a study of an infraclavicular block comparing ultrasound guidance and
nerve stimulator guidance in children.[4]
- 2 -
Introduction
Claimed benefits of ultrasound guided regional anaesthesia include
that it is easier to learn and perform, quicker to perform, has a faster
onset, results in higher success rates, results in more complete block,
requires lower volumes of local anaesthetic, and increases safety.[5]
Chapter (1)
- 3 -
Anatomy of Brachial Plexus
Anatomy of Brachial Plexus
Anatomy of Brachial Plexus:
The anterior horn cells that are cell bodies for motor neurons
resides in the ventral horn of the spinal cord and send their motor outflow
through the ventral root. The ventral roots exit the spinal cord and
combine with the dorsal roots to form spinal nerves .The spinal nerves
divide into anterior and posterior rami, and there are the anterior rami that
contribute to the formation of the brachial plexus.[6]
The brachial plexus receives contributions from cervical roots C5,
C6, C7, C8 and T1 .The sympathetic supply to the head and neck arises
from the first thoracic segment and reaches the spinal nerves through the
grey ramus from the inferior cervical ganglion .Damage to the T1 root
may result in an ipsilateral Horner's syndrome [Fig. 1].[6]
In the neck, the brachial plexus lies between the scalenus anterior
and scalenus 0medius and then deep to the sternocleidomastoid muscle.It
emerges from below the sternocleidomastoid muscle and three trunks are
formed above the clavicle[( upper) C5-C6, (middle)C7, (lower)C8-T1.[6]
Behind the clavicle, the anterior and posterior divisions of the
trunks reconfigure to form three cords. The upper two anterior divisions
unite together to form the lateral cord, the anterior division of the lower
trunk runs on as the medial cord, while all three posterior divisions unite
together to form the posterior cord.[6]
Chapter (1)
- 4 -
Anatomy of Brachial Plexus
Fig. (1): Brachial plexus from roots to terminal divisions.[6]
Roots :
The anterior rami of the spinal nerves of C5, 6, 7, 8 and T1 form
the roots of the brachial plexus; the roots emerge from the transverse
processes of the cervical vertebrae immediately posterior to the vertebral
artery, which travels in a cephalocaudal direction through the transverse
foramina. Each transverse process consists of a posterior and anterior
tubercle, which meets laterally to form a costotransverse bar.[6]
Chapter (1)
- 5 -
Anatomy of Brachial Plexus
The transverse foramen lies medial to the cost transverse bar and
between the posterior and anterior tubercles. The spinal nerves which
form the brachial plexus run in an inferior and anterior direction within
the sulci formed by these structures.
The dorsal scapular nerve arises from the C5 root and passes
through the middle scalene muscle to supply the rhomboidus and levator
scapulae muscles. The long thoracic nerve to the serratus anterior arises
from the C5,6 and 7 roots and also pierces the middle scalenus as it
passes posterior to the plexus.[6]
Trunks and divisions:
The trunks of the brachial plexus pass between the anterior and
middle scalene muscles.The superior trunk lies closest to the surface and
is formed by the C5 and C6 roots.The suprascapular nerve and the nerve
to the subclavius arise from the superior trunk. The suprascapular nerve
contributes sensory fibers to the shoulder joint and provides motor
innervation to the supraspinatus and infraspinatus muscles. The C7 root
continues as the middle trunk and the C8 and T1 roots join to form
inferior trunk. The trunks divide into anterior and posterior divisions,
which separate the innervations of the ventral and dorsal halves of the
upper limb.[6]
The phrenic nerve (C3, 4, 5) passes between the anterior and
middle scalenes and continues over the surface of the anterior scalene
muscle, thus a diaphragmatic twitch during interscalene brachial plexus
performed with a nerve stimulator may indicate placement of the needle
anterior to the plexus.[6]
Chapter (1)
- 6 -
Anatomy of Brachial Plexus
The spinal accessory nerve (CN XI) runs posterior to the brachial
plexus over the surface of the middle and posterior scalenes. Contact with
spinal accessory nerve with a nerve stimulator (stimulating twitch in the
trapezius) indicates placement of the needle posterior to the plexus.[6]
Cords and Branches:
The cords are named the lateral, posterior, and medial cord
according to their relationship to the axillary artery. The cords pass over
the first rib close to the dome of the lung and continue under the clavicle
immediately posterior to the subclavian artery. The lateral cord receives
fibers from the anterior divisions of the superior and middle trunks, and is
the origin of the lateral pectoral nerve (C5,6,7). The posterior divisions of
the superior, middle and inferior trunks combine to form the posterior
cord.[6]
The upper and lower subscapular nerves (C7, 8 and C5, 6
respectively) leave the posterior cord and descend behind the axillary
artery to supply the subscapularis and teres major muscles respectively.
The thoracodorsal nerve to the latissimus dorsi, also known as the middle
subscapular nerve (C6, 7, 8) arises from the posterior cord. The inferior
trunk continues as the medial cord and gives off the median pectoral
nerve (C8, T10), the medial brachial cutaneous nerve (T1) and the medial
antebrachial cutaneous nerve (C8, T1). The lateral cord divides into the
lateral root of the median nerve and the musculocutaneous nerve. The
musculocutaneous nerve leaves the brachial plexus sheath high in the
axilla at the level of the lower border of the teres major muscle and passes
into the substance of the coracobrachialis muscle.[6]
Chapter (1)
- 7 -
Anatomy of Brachial Plexus
The posterior cord gives off the axillary nerve at the lower border
of the subscapularis muscle and continues along the inferior and posterior
surface of the axillary artery as the radial nerve. The axillary nerve
supplies the shoulder joint, the surgical neck of the humerus, the deltoid
and the teres minor muscles before ending as the superiorlateral brachial
cutaneous nerve.[6]
The radial nerve continues along the posterior and inferior surface
of the axillary artery. The medial cord contributes the medial root of the
median nerve and continues as the ulnar nerve along the medial and
anterior surface of the axillary artery. The medial and lateral roots join to
form the median nerve which continues along the posterior and lateral
surface of the axillary artery.[6]
The connective tissue of the prevertebral fascia and the anterior and
middle scalenes envelops the brachial plexus as well as the subclavian
and axillary arteries in a neurovascular "sheath". The tissue is densely
organized as it leaves the deep cervical fascia proximally, but becomes
more loosely arranged distally. The sheath blends with the fascia of the
biceps and brachialis muscles distally.[7]
The Brachial Plexus "sheath"
Anatomic dissection, histological examination, and CT scanning
after injection of radio contrast into the brachial plexus sheath
demonstrate the presence of connective tissue septae which extend inward
from the fascia surrounding the sheath. These thin filamentous connective
tissue septae frequently adhere to nerves and vessels leaving no free space
between layers and compartmentalizing the components of the sheath.
Chapter (1)
- 8 -
Anatomy of Brachial Plexus
Injection into the sheath in cadavers results in the filling of multiple
discrete interconnecting "grape-like" bubbles.[8]
Some controversy exists as to what degree the septae limits the
spread of local anaesthetics within the sheath.Some investigators propose
that the septae significantly limit the spread of solutions when a single
injection technique is used to perform brachial plexus block, and suggest
that the term "sheath "has been misapplied to the connective tissue
surrounding the brachial plexus.This may explain why anaesthesia
occasionally is complete and rapid in onset in some nerves, but delayed
and incomplete or completely absent in others.Other investigators have
demonstrated the existence of communications between the
compartments within the sheath. Methylene blue and latex solutions
injected in cadavers stain and surround the median, radial and ulnar
branches despite the presence of septae.The presence of communications
may explain why single injection techniques have success rates
comparable to multiple injection techniques. Complete spread of local
anaesthesia through a single injection technique possibly occurs through
many routes, such as spread of local anaesthesia through channels
between compartments, spread through communications at proximal
levels in the sheath, and diffusion through the thin septae between
compartments.[8]
Chapter (2)
- 9 -
Basic Principles & Physics of Ultrasound
Basic Principles and Physics of
Ultrasound
Introduction:
Ultrasound is a form of mechanical sound energy that travels
through a conducting medium (e.g., body tissue) as a longitudinal wave
producing alternating compression (high pressure) and rarefaction (low
pressure). Sound propagation can be represented in a sinusoidal
waveform with characteristic pressure, wavelength, frequency, period and
velocity.[9]
The velocity of sound (speed + direction of sound transmission)
varies for different biological media but the average value is assumed to
be 1,540 m/sec (constant) for human soft tissues. The frequency (ƒ) of
medical ultrasound is usually in the range of 2-15 MHz (cycles per sec)
and is inaudible to the human ear.[9]
Because the speed of sound (c) = ƒ x λ, higher frequency waves have
shorter wavelengths (λ) and vice versa.
Transducer Properties:
Linear and curvilinear (or curved) transducers are most useful for
nerve imaging to provide high resolution images. Sector phased array
transducers are less suitable because of the resultant "grainy" images.
Broad bandwidth transducers are designed to generate more than one
frequency. However there is one frequency at which the piezoelectric
transducer is most efficient in converting electrical energy to acoustic
energy and vice versa. This is called the resonance frequency and is
Chapter (2)
- 10 -
Basic Principles & Physics of Ultrasound
determined by the thickness of the piezoelectric element. With broad
bandwidth transducers, the operator can select the examination frequency
to match the target requirement.[9]
Tissue Penetration:
As the ultrasound beam passes through tissue layers, amplitude of
the original signal becomes attenuated with depth of penetration as a
result of certain factors as:
1. Reflection and scatter at interfaces.
2. Absorption (conversion of acoustic energy to heat).
3. Beam divergence.
4. Refraction.[9]
Attenuation indicates a change in signal intensity level in decibel
(dB) and a reduction in 3 dB corresponds to diminution of the original
intensity by half. Signal attenuation is closely related to the ultrasonic
frequency and the type of tissue medium.[10]
To compensate for attenuation, it is possible to amplify the echo
signals detected by the transducer before display. The degree of receiver
amplification is called the gain. Increasing the gain will amplify only the
returning signal and not the transmit signal. An increase in the overall
gain will increase brightness of the entire image, including the
background noise. Preferably, the time gain compensation is adjusted to
selectively amplify the weaker signals arriving from more distal and
deeper locations.[10]
Echo Reflection and Scattering:
Chapter (2)
- 11 -
Basic Principles & Physics of Ultrasound
The amplitude of a reflected echo to the transducer is determined by
the difference in acoustic impedances of the two tissues at the interface
(the degree of impedance mismatch). Acoustic impedance is the
resistance of a tissue to the passage of ultrasound. Mathematically, it is
the product of the medium density and speed of sound.[11]
Major impedance mismatch exists at a soft tissue-air interface. For
this reason, it is clinically important to apply sufficient conducting gel (an
acoustic coupling medium) on the transducer surface to eliminate any air
pocket between the transducer and skin surface. Otherwise much of the
ultrasound beam will be reflected and tissue penetration will be
limited.[11]
The angle of the incident beam also has a major influence on the
signal amplitude returning to the transducer. Specular reflection refers to
a perpendicular reflection after a beam hits a smooth mirror like interface
at a 90 degree incidence. An incident beam hitting the interface at an
angle will result in a beam being deflected away from the transducer at an
angle equal to the angle of incidence but in the opposite direction (angle
of reflection). When this happens, the returned signal is weakened and a
diminished image is displayed. Examples of a specular reflector are block
needles, fascia sheath, diaphragm and walls of major vessels.[11]
Refraction:
After reflection and scattering, the remainder of the incident beam is
refracted with a change in the transmitted beam direction. Refraction
occurs only when the speeds of sound are different on the two sides of the
interface. The degree of beam change (bending) is dependent on the
change in the speed of sound traveling from one medium on the incident
Chapter (2)
- 12 -
Basic Principles & Physics of Ultrasound
side to another medium on the transmitted side (Snell’s Law). With
medical imaging, fat contribute to serious refraction, image distortion and
some of the difficulties encountered in obese patients. Refraction
encountered with bone imaging is even more serious leading to a major
change in the direction of the incident beam and image distortion.[11]
Image Display:
When the echo returns to the transducer, its amplitude is represented
by the brightness of a dot on the display. Its position on the display is
determined by the depth from which the returning echo is originated. The
depth (D) is determined by the time (T) it takes for a wave to travel to and
from a structure (return trip thus 2 times) and can be expressed
mathematically as D = c T /2 where the speed of sound (c) is assumed to
be 1,540 m/sec (average).
Combination of all the dots forms the final image. Strong reflections
give rise to bright dots (e.g., diaphragm, gallstone, bone are hyperechoic).
Weaker reflections produce grey dots (e.g., solid organs) and no
reflection produces dark dots (e.g., fluid and blood filled structures are
hypoechoic or anechoic); this information is then translated onto a
monitor.[12]
Hypoechoic structures appear black on the screen when ultrasound
waves are not returned to the transducer. This can be due to significant
beam attenuation or transmission. Veins and arteries appear very dark
(anechoic) because the beam passes easily through fluid filled structures
without significant reflection. Arteries can be differentiated from veins
since arteries are pulsatile and difficult to collapse while veins are non-
pulsatile and easily collapsed (disappeared from the screen) under
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