AXILLARY BLOCKS

Indications

Surgical procedures distal to elbow

Forearm

Hand and digits

 

LOCAL ANESTHETIC AGENTS

DRUG

 Concentration Onset Duration w/o Epi DurationW/ Epi

Procaine

 2% 10-15 min 20-30 min 30-60 min

Chloroprocaine

 2% 15-30 min 30-60 min 60-90 min

Lidocaine

 1% 12-20 min 60-90 min 150-180 min

Mepivicaine

 1% 20-30 min 150-180 min 180-240 min

Prilocaine

 1% 10-15 min 180-240 min 240-360 min

Bupivicaine

 0.25% 20-30 min 420-900 min N/A

Bupivicaine

 0.5% 10-20 min 540-1200 min N/A

 

AXILLARY ANATOMY

 

CROSS SECTION BRACHIAL SHEATH

 

 

TECHNIQUES

Patient Positioning
Supine

 

 

Arm abducted (hyperabduction can stretch the plexus sheath over the head of the head of the humerous, obstructing proximal flow of local solution)

 

 

 

 

 

Elbow flexed at 90 degrees and externally rotated until the dorsum of the hand is lying beside his head, parallel to the long axis of his body

 

 

 

              

 
 
Type of Needle
22 gauge B- bevel

1 ½ inches in length

Preferred for brachial plexus techniques

B- bevel needles create a distinct loss of resistance or “pop”

 

 

 
Transarterial (transvascular) Technique
Palpate axillary pulse and insert needle, through small intradermal skin wheal, where pulse is felt

Aspirate  bright red blood and advance needle until blood is no longer obtained

Inject 40 cc local at this point or

Alternate Approach – inject 20 cc in front of artery and 20 cc behind the artery

 

 

Paresthesia Technique
lnsert needle through small intradermal skin wheal

Direct needle toward axillary artery

If artery is entered, then redirect needle until paresthesia is obtained

Inject 40 cc of local at this point or

Alternate Approach- elicit paresthesia in the ulnar, median, and radial nerves injecting local at each site totaling 40 cc’s 

 

 
Peripheral Nerve Stimulator Technique
Attach positive (anode) lead to patients chest -“Positive to Patient”

Attach negative (cathode) lead to the metal hub or shaft of the needle- “Negative to Needle”

Insert needle through small intradermal skin wheal

Advance until you feel needle tip is near desired nerve

Turn on PNS (5-10 mA) and observe for muscle contraction – distal contraction is desired

Advance needle until you see maximal contraction

Reduce current output (0.5 to 1 mA)

Advance/ withdraw the needle until contractions are noted – at this low setting this suggest that the tip is on or very near the nerve

Inject 1 or 2 cc’s of local

If correctly placed, contractions should fade in 5-10 seconds

Inject 5-10 cc’s of local aspirating for blood with every 5 cc’s

Repeat this process for each nerve (Median, Ulnar, Radial, and Musculocutaneous)

Total local solution should equal 40 cc’s 

 

   

 
 

Assessment of Efficacy 

 
Musculocutaneous Nerve

Reflexes

Observe for loss of biceps tendon reflex

Motor

Observe for decreased ability to flex elbow joint

Sensory

Check sensation over dorsoradial surface of distal forearm as far as the wrist and base of thumb

 

  

Radial Nerve

Reflexes

Observe for absence of tricep reflex

Motor

Observe for decreased ability to adduct arm at shoulder and extend forearm at elbow

Sensory

Check sensation at webspace between thumb and first finger

 

 
Median Nerve

Reflexes

No superficial or deep tendon reflexes

Motor

Observe for decreased ability to flex the distal interphalangeal joint of index and second finger

Observe for decreased ability to abduct the thumb from the palm

Sensory

Check sensation on the palmar surface of the thumb

 

Ulnar Nerve

Reflexes

 No superficial or deep tendon reflexes

Motor

Observe for decreased ability to flex the distal interphalangeal joint of the ring and small finger

Observe for decreased ability to abduct small finger

Sensory

Check sensation over the dorsal surface of the tip of the small finger

 

 

Peripheral Nerve Innervation of The Upper Arm

 

COMPLICATIONS

Intravascular injection (systemic toxicities)

Hematoma

Post-op neuropathies

Failure to block musculocutaneous nerve

 

References

 

Questions