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Needling Technique - In Plane

THERE ARE 2 COMMON NEEDLE INSERTION APPROACHES AND 2 TYPES OF NEEDLE TO TRANSDUCER ALIGNMENT

 

Approach # 1 IN PLANE (IP) Needle Approach

 

The needle is placed inline with and parallel to the transducer (ultrasound beam). Both the needle shaft and tip are visualized.

Axillary block is used as an example.

Needle to nerve contact can be followed in real time. The full length of the needle shaft and tip can be visualized.

The needle tip is seen in contact with the nerve (honeycomb structure)

AA = axillary artery.

 

APPROACH # 2: OUT OF PLANE (OOP) NEEDLE APPROACH

 

The needle is placed perpendicular to the transducer. The needle shaft and tip are visualized as a hyperechoic dot on ultrasound.

The femoral nerve block is used as an example.

In this case, needle, nerve and tissue movements are observed. The needle tip (NT) may be difficult to locate accurately without the use of echogenic tip needles.
Actual needle to nerve contact can be confirmed by nerve stimulation and
local anesthetic (LA) spread pattern.
FA, FN & FV = femoral artery, nerve & vein; IPM = iliopsoas muscle

 

STEPS TO BUILD A PORCINE PHANTOM

  1. Prepare a piece of pork shoulder with the humerus attached.
  2. Carve to 20 cm x 12 cm x 8 cm (length x width x height).
  3. Remove the skin and deodorize the pork specimen by soaking it in approximately 30 mL of 70% alcohol inside a plastic bag for 8 to 10 hours at 4˚C.
  4. Use a metal or plastic rod (approximately 1.5 cm in diameter) to create a 10cm long tunnel within the muscle layers approximately 3 cm from the surface.
  5. Insert a bovine tendon (approximately 8 cm long and 1 cm in diameter) inside the tunnel; ultrasound appearance of tendon and nerve is similar.
  6. Use a smaller tendon for advanced practice.
  7. Wrap up the whole phantom in a transparent para film and reinforce exteriorly by a surgical paper towel.
  8. Store specimen at 4˚C until use.

 

Short axis (x-section) view
Longitudinal view

 

In Plane Needle Insertion Practice

A. The needle is inserted in plane with the transducer but the needle image is not seen.

 

B. Maneuver # 1: Slide the transducer back and forth slowly over the needle until the needle image is seen. Hold the needle steady.

 

C. Maneuver # 2: Wiggle the needle tip from side to side until the needle is seen. Hold the transducer steady.

 

Out of Plane Needle Insertion Practice

 

Please refer to Needle Localization.

 

NEEDLE HANDLING

 

Proper needle handling skills are required for accurate and smooth needle insertion during ultrasound guided nerve blocks. If the operator is not ambidextrous, and prefers to use the dominant hand to handle the needle and inject local anesthetic, then the operator must choose a proper body location and orientation in relationship to the patient.

 

This is an example of a right handed operator using the right hand to hold the needle for a left sided interscalene block. Note that the operator is standing on the left side of the patient below the clavicle.
This is an example of a right handed operator using the right hand to hold the needle for a right sided interscalene block. Note that the operator is now standing on the right side of the patient above the clavicle.

 

BODY ERGONOMICS

 

Proper body ergonomics to handle the transducer and the needle, to view the screen, and to position the patient are essential for block success and to avoid operator fatigue and body injury. Below are some examples of proper and improper body ergonomics.

 

Proper operator and screen orientation; note that the ultrasound machine is placed directly in front of the operator to provide a direct line of vision.

 

Improper operator and screen orientation; note that the operator’s head is turned almost 90 degrees to view the ultrasound image on the screen.

 

Proper body position and bed height for the procedure

 

Improper body position; the bed is too low for the procedure

 

Proper transducer holding skill; the hand is placed close to the transducer contact surface

 

Improper transducer holding position; the hand is high up on the transducer

 

Proper hand and arm positions; both hands and arms are comfortably supported

 

Improper hand and arm positions; both the arm holding the transducer and the hand holding the needle are not supported

 

NEEDLE TO NERVE CONTACT AND INJECTION STRATEGY

 

1. Perineural Injection

  • The goal is to place the needle tip on each side of the target nerve (i.e., perineural) but not inside the nerve (i.e., intraneural).
  • Avoid direct head-on needle to nerve contact (figure A).

 

  • Aim to inject local anesthetic around the nerve and not inside the nerve (figures B and C). Perineural injection is visualized as an expanding collection of hypoechoic fluid around the nerve. Circumferential spread is generally a good indication of adequate local anesthetic spread (“donut sign”).

 

Figure A shows needle in contact with nerve

 

Figures B & C show local anesthetic injection around the nerve

 

LA = local anesthetic

 

White arrows = block needle

 

Yellow arrowhead = nerve

 

2. Recognition of Improper Local Anesthetic Spread

 

An Illustration of Local Anesthetic Spread During Femoral Nerve Block

 

Figure A shows an improper injection outside the fascia iliaca (FI). Arrows show tissue expansion outside the fascia.

FA = femoral artery		 Figure B shows a proper injection deep to the fascia iliaca (FI). Arrows show fluid expansion deep to the fascia.

 

An Illustration of Proper and Improper Local Anesthetic Spread During Popliteal Sciatic Nerve Block

 

Figure A illustrates improper injection and subsequent hypoechoic local anesthetic spread (asterisk) outside the fascial sheath of the sciatic nerve (hyperechoic structure) in the popliteal region.
Figure B illustrates proper injection (asterisks) inside the fascia sheath of the sciatic nerve.

 

An Illustration of Proper and Improper Local Anesthetic Spread During Supraclavicular Brachial Plexus Block

 

Figure A illustrates improper injection and hypoechoic local anesthetic (LA) spread outside the brachial plexus sheath.

 

Arrowheads = nerve trunks

 

FR = first rib

 

PL = pleura

 

SA = subclavian artery

Figure B illustrates proper injection (LA) inside the expanded brachial plexus sheath.

 

3. Recognition of Intraneural Injection

  • Intraneural injection is manifested by an expansion of nerve diameter (yellow arrowheads) with as little as 1mL of injection (figure B).
  • Another hint of an intraneural puncture is nerve movement towards the needle as the needle is withdrawn. The nerve should be moving away from the needle under normal circumstances.

Ultrasonographic Appearance of An Intraneural Injection

 

Pre-injection
Post-injection

 

4. Hydro Dissection Technique

  • The hydro dissection technique is most useful for “dissecting” out the intermuscular or interfascial plane in which a small nerve lies.
  • Injection of 5-10 mL of fluid (saline or D5W) through the needle can distend and open up the narrow space so that the small nerve is more clearly visualized before local anesthetic injection.
  • Hydro dissection is particularly useful for blockade of smaller nerves located between muscular planes e.g., 1) ilioinguinal and iliohypogastric nerves; 2) the rectus sheath block; 3) obturator nerve; 4) saphenous nerve and 5) transverse abdominis plane block.
Figure A shows hypoechoic ilioinguinal/iliohypogastric nerves (arrowheads) within the plane between the internal oblique muscle (IOM) and the transverse abdominis muscle (TAM).

 

Figure B shows needle (arrows) approaching the nerves using the in plane needle approach. It is difficult to tell if the needle tip is indeed inside the intermuscular plane.

 

Figure C shows injection of a small amount of fluid (“hydro dissection”) to open up the narrow plane. A small hypoechoic fluid collection is now seen above the nerves.