5-175
c. Look for paresthesias by inserting the needle through the skin wheal and directing it slightly above or
below the arterial pulsation (attempting to stimulate the median, ulnar or radial nerve).
d. Angle the needle to almost the same plane as the sheath. When the patient reports a paresthesia,
aspirate, then inject 2-3 ml of local anesthesia as a test. The paresthesia should fade. If so, continue
to inject, aspirating the syringe every 5 ml to check for intravascular injection, until a volume of 40cc
has been injected.
e. Intense burning associated with the injection of a small volume indicates possible intraneural injection
(STOP INJECTING).
f. Use the remaining 10 ml are to block the musculocutaneous, intercostobrachialis and medial
cutaneous nerves as below. Prep the areas as in 4b above.
g. Musculocutaneous nerve: insert the needle into the body of the coracobrachialis muscle until it
touches the humerus, withdraw 2-3 mm, then inject 5 ml of the remaining anesthetic solution into
the muscle.
h. Intercostobrachialis and medial brachial cutaneous n.: subcutaneously direct the needle inferiorly and
superiorly to the insertion site for the musculocutaneous block and inject the remaining 5-10 ml
solution as a ring block.
- After placing the block, bring the arm to the side and massage the axilla for a few minutes to spread the
anesthetic. Maintain pressure over auxiliary injection site to decrease bleeding and keep agent high
in axilla. - Continually assess the patient for signs of systemic absorption of the anesthetic and possible toxic
reaction. Elevated vital signs of excitement are seen at lower blood levels of anesthetic, progressing to
CNS depression as blood levels rise.
Warning signs include: Patient reporting metallic taste in mouth or circumoral paresthesias, tinnitus,
drowsiness/dizziness/disorientation, visual disturbance, slurred speech, generalized twitching and tremors. - Always be prepared to provide airway and cardiovascular support whenever administering brachial plexus
blockade. - Assess the block - ”Push, pull, pinch, pinch” (support patient’s arm during these maneuvers!)
PUSH: The patient attempts to extend the arm. Inability to do so implies block of the radial n.
PULL: Attempt to flex the arm at the elbow; inability to do so implies musculocutaneous n. block.
PINCH: The hand at the base of the thenar eminence (prominence at the base of the thumb); sensory
loss implies median n. block.
PINCH: The base of the little finger; sensory loss implies ulnar n. block. Inability to spread fingers against
resistance implies ulnar n. block. - Apply tourniquet above level of surgery prior to the operation.
What Not To Do:
Contraindications: Uncooperative patient/refusal, bleeding disorders, infection at injection site or allergies to
local anesthetics.
Complications: Toxic systemic absorption/intravascular injection that can lead to cardiovascular collapse.
Hematoma at injection site from axillary artery puncture. Accidental injection of agent into the nerves.