nerve blocks in anaesthesia

1. NERVE BLOCKS

2. AXILLARY BRACHIAL PLEXUS BLOCK
• Essentials
• Indications: elbow, forearm and hand surgery
• Landmarks: axillary artery pulse
• Any of the following three end points: hand
paresthesia; arterial blood on aspiration
(axillary artery)
• Local anesthetic: 20-30 mL

4. • Equipment
• sterile towels and gauze packs
• 2x20-mL syringes containing LA
• A 3-mL syringe plus 25-gauge needle with LA
for skin infiltration
• A 3.5-cm, 22-gauge, short-bevel insulated
stimulating needle
• Sterile gloves; marking pen

5. • Landmarks and Patient Positioning
• The patient is placed supine with the head facing away
from the side to be blocked. The arm is abducted to form
an approximately 90° angle in the elbow joint.
• Excessive abduction in the shoulder joint should be
avoided because it makes palpation of the axillary artery
pulse difficult.
• Excessive abduction can also result in stretching and
"fixing" of the brachial plexus. Such stretching of the plexus
components can increase its vulnerability during needle
advancement.

6. Surface landmarks:
• 1. Pulse of the axillary artery
• 2. Coracobrachialis muscle
• 3. Pectoralis major muscle

9. • Technique
• After thorough skin preparation, the pulse of the axillary artery is
palpated high in the axilla. Once the pulse is felt, the artery is fixed
between the index and the middle fingers and firmly pressed against the
humerus to prevent "rolling" of the axillary artery during block
performance. At this point, movement of the palpating hand and the
patient's arm should be minimized because the axillary artery is highly
movable in the adipose tissue of the axillary fossa. The index and middle
fingers should be pressed firmly against the arm, straddling the pulse of
the axillary artery immediately distal to the insertion of the pectoralis
major. This maneuver shortens the distance between the needle
insertion site and the brachial plexus block by compressing the
subcutaneous tissue. It also helps in stabilizing the position of the artery
and needle. LA is infiltrated subcutaneously at the needle insertion site.

11. • PERIARTERIAL TECHNIQUE
• Once through the skin, the needle is slowly advanced directly below
the pulse until stimulation of the brachial plexus is obtained.
Typically, this occurs at a depth of 1 to 2 cm in most patients. The
needle should be advanced gently until a radial nerve twitch
(extension of wrist and/or fingers) is obtained, and 10 to 15 mL of
local anesthetic is deposited after negative aspiration.
• The needle is then withdrawn completely and reinserted above the
artery without moving the palpating hand. Advancing slowly, the
median nerve should be encountered within 1 to 2 cm, resulting in
finger flexion. The needle is then advanced slightly deeper until the
ulnar twitch reappears. At this point, a further 5 to-10 mL of local
anesthetic is deposited after negative aspiration.

12. • TRANSARTERIAL TECHNIQUE
• The needle enter the artery (bright red blood noticed in tubing),
advanced further until the aspiration is negative for blood. This
indicates that the needle tip is now outside of the artery and
positioned posterior to the artery.
• With intermittent aspiration, two thirds of the LA can be
deposited here.
• The needle is then withdrawn back through the artery to again
obtain the blood flow.
• When the needle reenters the artery (blood flow on aspiration)
and exits anterior to the vessel, the remaining one third of the LA
is injected at this superficial location.

13. • The onset time for this block ranges between
15 and 25 minutes.
• The first sign of the blockade is loss of
coordination of the arm and forearm muscles.
This sign is usually seen sooner than the onset
of a sensory or temperature change.
• Complications: Infection, hematoma, vascular
puncture, LA toxicity, nerve injury.

14. CUTANEOUS NERVE BLOCKS
• Indications: mostly used as a supplement to
major blocks of the upper extremity
• Local anesthetic: 5-10 mL

15. Intercostobrachial Nerve Block
• Anatomy
• It provides innervation to the skin of the axilla and the medial aspect of the
proximal arm. The intercostobrachial nerve communicates with the medial
cutaneous nerve of the arm, which is a branch of the brachial plexus. Both
nerves are anesthetized by subcutaneous infiltration of the skin of the medial
aspect of the arm.
• Indications
• Combined with brachial plexus block to achieve more complete anesthesia of
the upper arm.
• Technique
• A 1.5” 25G needle is inserted at the level of the axillary fossa. The entire width
of the medial aspect of the arm is infiltrated with local anesthetic to raise a
subcutaneous wheal of anesthesia.

17. WRIST BLOCK
Essentials
• Indications: surgery on the hand and fingers
• Nerves: radial, ulnar, median
• Local anesthetic: 5mL for median and ulnar
nerve, 10 mL for radial nerve
• Never use an epinepherine-containing local
anesthetic

19. Equipments
• Sterile towels and gauze packs
• Two 10-mL syringes containing local
anesthetic
• A 1.5-inch, 25-gauge needle

20. Landmarks and Patient Positioning
• The patient is positioned supine, with the arm in abduction. The wrist is
best kept in slight extension.
Maneuvers to Facilitate Landmark Identification
• The superficial branch of the radial nerve emerges from between the
tendon of the brachioradialis and the radius just proximal to the easily
palpable styloid process of the radius (circle). The median nerve is located
between the tendons of the flexor palmaris longus (white arrow) and the
flexor carpi radialis (red arrow). The flexor palmaris longus tendon is usually
the more prominent of the two, and it can be accentuated by asking the
patient to oppose the thumb and 5th finger while flexing the wrist; the
median nerve passes just lateral to it. The ulnar nerve passes between the
ulnar artery and tendon of the flexor carpi ulnaris . The tendon is superficial
to the ulnar nerve.

24. • Block of the Ulnar Nerve
• Inserting the needle under the tendon of the flexor
carpi ulnaris muscle close to its distal attachment
just above the styloid process of the ulna. The
needle is advanced 5 to 10 mm to just past the
tendon. After negative aspiration, 3 to 5 mL of LA is
injected. A subcutaneous injection of 2 to 3 mL of LA
just above the tendon for blocking the cutaneous
branches of the ulnar nerve, which often extend to
the hypothenar area.

26. • Block of the Median Nerve
• Inserting the needle between the tendons of the flexor palmaris
longus and flexor carpi radialis. The needle is inserted until it
pierces the deep fascia(heard as a “click’), and 3 to 5 mL of LA is
injected. It is more reliable to simply insert the needle until it
contacts the bone. The needle is withdrawn 2 to 3 mm, and the
LA is injected.
• Fan technique
• Paresthesia in the median nerve distribution warrants a 1- to 2-
mm withdrawal of the needle, followed by a slow measured
injection of the LA. If paresthesia worsens or persists, the needle
should be removed and reinserted.

28. • Block of the Radial Nerve
• "field block"
• requires more extensive infiltration because of its
less predictable anatomic location and division
into multiple smaller cutaneous branches. 5 ml of
LA should be injected subcutaneously just
proximal to the radial styloid, aiming medially.
Then the infiltration is extended laterally, using
an additional 5 mL of LA.

30. • A typical onset time for a wrist block is 10 to 15
minutes.
• Sensory anesthesia of the skin develops faster
than the motor block.
• Placement of an Esmarch bandage or a tourniquet
at the level of the wrist is well tolerated and does
not require additional blockade.
• Complications: Infection, hematoma, vascular
damage, nerve injury.

31. DIGITAL NERVE BLOCK
• technique of blocking the nerves of the digits
to achieve anesthesia of the finger(s)
• essentially devoid of systemic complicationss
• effective method of anesthesia for minor
surgical procedures on the digits.

33. • Position: hand is pronated and rested on a flat
surface or supported by an attendant.
• Equipment:
Sterile towels and 4"x4" gauze packs
A 10-mL syringe with local anesthetic
One 1½" 25-gauge needle

34. • Block of Volar and Dorsal Digital Nerves at the Base of
the Finger
• needle is inserted at a point on the dorsolateral aspect of
the base of the finger and a small skin wheal is raised-
>directed anteriorly toward the base of the phalanx->
advanced until the it contacts the phalanx. One mL of
solution is injected as the needle is withdrawn 1 to 2 mm
from the bone contact. An additional 1 mL is injected
continuously as the needle is withdrawn back to the skin.
Repeated on each side of the base of the finger to achieve
anesthesia of the entire finger.

36. • Transthecal Digital Block
• With the patient's hand supinated, the flexor tendon is
located. Using a 25 to 27 gauge 1” needle, 2 mL of local
anesthetic is injected into the flexor tendon sheath at
the level of the distal palmar crease. The needle should
puncture the skin at a 45-degree angle. Free flow of
medication as the potential space between tendon and
sheath is entered to be ensured. Proximal pressure is
then applied to the volar surface for the diffusion of the
medication throughout the synovial sheath.

38. • Typical onset time for this block is 10-20
minutes.
• Complications: Infection, hematoma, vascular
puncture, gangrene of the digit(s), nerve
injury.