4. CONTENTS
•Anatomy
•Rationale
•US In Regional Anesthesia
– US Principles
– US Equipments
– Transducers (Probes)
•Peripheral nerve imaging
– Probe Orientation
– Scanning Techniques
•Imaging Of Brachial Plexus
– The Intercsalene Region
– The Supraclavicular Region
– The Infraclavicular Region
– The Axillary Region
•Lumbar Plexus
– Femoral Nerve
– Sciatic Nerve
– Obturator Nerve Block.
5. Rationale:
In recent years there has been a growing interest
in the practice of regional anesthesia and, in
particular, PNB for surgical anesthesia and
postoperative analgesia.
Peripheral nerve blocks have been found to be
superior to general anesthesia:
(1) Effective analgesia with few side effects
(2) Hasten patient recovery
6. • Imaging guidance for nerve localization holds the promise of
improving block success and decreasing complications.
• Essentially "blind" procedures, since they both rely on indirect
evidence of needle-to-nerve contact, Seeking nerves by trial and error
and random needle movement can cause complications.
• US seems to be the one most suitable for regional anesthesia: By
Provide anatomic examination of the area of interest.
Visualize neural and the surrounding structures.
Navigate the needle toward the target nerves.
Visualize the pattern of local anesthetic spread.
7. US Principles
Depending on the amount of wave returned, anatomic
structures take on different degrees of echogenicity.
Structures with high water content, such as blood vessels and
cysts, appear Hypoechoic (black or dark), because
ultrasound waves are transmitted through the structures
easily with little reflection.
On the other hand, bone and tendons block ultrasound wave
transmission and the strong signal returned to the
transducer gives these structures a Hyperechoic
appearance (bright, white) on the screen
8. Transducers (probes)
Deep organs scanning such as liver, gallbladder,
and kidneys requires low-frequency probes
(3-5 MHz).
Superficial structures such as the brachial plexus,,
requires high-frequency probes (10-15
MHz) that provide high axial resolution BUT
Beam penetration is limited to 3 to 4 cm.
9. Probe orientation
It is advisable to follow the tradition of pointing the
Premarked end of the probe towards the head
when scanning in a sagital or parasagital plane.
Pointing towards the patient's right when scanning in
an axial plane.
10. Scanning technique
Patient positioning for each block is essentially the
same as is used for standard, non-image-guided
peripheral nerve blocks.
Sterile technique should be followed, especially
when a continuous catheter technique is
performed, in which case a long sterile sheath
covering the probe and the cord and sterile
conducting gel are recommended.
29. General Principles of USGNB
Techniques
The quality of US nerve images captured is dependent on the
quality of the ultrasound machine and transducers, proper
transducer selection (e.g., frequency) for each nerve
location, the anesthesiologist's familiarity and interpretation
of sonographic anatomy pertinent to the block, and good
eye-hand coordination to track needle movement during
advancement.
Optimal patient positioning and sterile technique are
encouraged.
Nerve localization by US can be combined with nerve
stimulation. Both tools are valuable and complementary.
30. Two approaches are available to block peripheral nerves:
The first approach aims to align and move the block needle
inline with the long axis of the US transducer, so the needle
stays within the path of the US beam. In this manner, needle
shaft and tip can be clearly visualized. This is preferred when it
is important to track the needle tip at all times (supraclavicular
block to minimize inadvertent pleural puncture).
The second approach places the needle perpendicular to the
probe, in this case, the ultrasound image captures a transverse
view of the needle, which is shown as a Hyperechoic "dot" on
the screen.
Accurate moment-to-moment tracking of the needle tip location can
be difficult, and needle tip position is often inferred indirectly by
tissue movement. D5W
