Download the axillary nerve block for upper extremity anesthesia

THE AXILLARY NERVE BLOCK FOR UPPER EXTREMITY ANESTHESIA IN
THE EMERGENCY DEPARTMENT
MARK E. BORDEN, MD
EDWARD A. PANACEK, MD, MPH
Revision 04/ 22/07
Word count: 2612
INTRODUCTION
The Emergency Physician (EP) is frequently faced with the need for good upper
extremity anesthesia. Forearm fractures, large and complex lacerations, and other
conditions of the upper extremity are regularly treated in the Emergency Department
(ED). Multiple techniques of regional anesthesia can be used to achieve pain control for
fracture reduction. While hematoma blocks and Bier Blocks are frequently used, both
have inherent difficulties and mixed efficacy (7,15). Procedural sedation (PSA) is also
available for procedures. PSA requires more personnel and monitoring and generally
results in a longer recovery time, and ED stay. The axillary nerve block (ANB) provides
another alternative for achieving excellent upper extremity anesthesia. Although the
technique is commonly and effectively performed by anesthesiologists, and by some
emergency physicians, it is not well described in the emergency medicine literature. The
ANB is an excellent, and very safe, regional anesthesia technique with the potential of
reducing ED length of stay and improving overall patient satisfaction.
We report six cases of emergency physician performed axillary nerve blocks that were
successful in providing analgesia. We also describe the technique in detail.
Technique
Preparation
Patient Selection: Patients in whom a motor and sensory assessment of the extremity is
difficult or abnormal should not undergo an ANB. In addition, patient feedback during
the procedure is helpful. Elbow dislocation, and supracondylar humerus fractures should
not be reduced by the use of regional anesthesia, as there will be a delay in the
neurovascular reassessment, and these injuries are prone to neurovascular compromise.
Inability to abduct the arm will make the procedure more challenging, but this is not an
absolute contraindication. Infection at the injection site is a contraindication.
Patient Education: Explain to the patient that he/she will receive a “large injection of
numbing medicine through a very small needle.” During the injection the patient may feel
sensations that “shoot” to the hand or arm (paresthesias) and if these feelings are noted,
he/she should tell you. Tell the patient that the pain will “go away,” and to a greater or
lesser degree, so will the ability to move the arm. Since tricep motor function (extension)
is usually lost to a greater degree than bicep/brachialis function (flexion), it is a good idea
to warn the patient not to “scratch his/her nose,” as if they do so they may “hit” their nose
instead.
Tourniquet placement. Placement of a blood draw type tourniquet distal to the injection
site encourages proximal movement of the anesthetic within the axillary sheath (see
discussion). The tourniquet is placed while the arm is at the patient’s side. If the
tourniquet is placed as high as possible on the patient’s arm before abduction of the arm,
the tourniquet will generally be very close to the ideal location of three centimeters from
the axillary crease upon abduction. The tourniquet is left in place for ten minutes
following the injection.
Approach
The nerves that you will be blocking lie within a neurovascular sheath. As the Medial,
Posterior, and Lateral cords of the Brachial Plexus enter the arm they divide into the
Median, Radial, Ulnar, Musculocutaneous and Axillary Nerves. The Axillary Artery
(becoming Brachial Artery) and Axillary Vein are within the neurovascular sheath at this
level, as well. Two approaches to blocking this area are especially well suited for
Emergency Department use. The ANB has been thoroughly studied in the pediatric
population (13, 14, 17, 18) and is also very well suited for pediatric use. These techniques
are described.
Transarterial
ANB is commonly performed through the transarterial approach (1,2,3,8). The
transarterial approach takes advantage of the fact that the axillary artery is within the
neurovascular sheath. By going through the artery, anesthetic is placed reliably within
the neurovascular sheath, and can then diffuse, over time, into the nerves. Palpation of the
artery should be done with several fingers to better localize the vessel. By palpating
immediately proximal to the tourniquet, and injecting proximal to the palpating fingers,
the physician is able to inject very proximally on the arm. This will ensure the highest
probability of success. Though relatively superficial, the axillary artery can be difficult to
palpate in some patients, and time should be spent to ensure accurate localization.
Injection. A 5/8 inch straight 25 gauge or ¾ inch 25 gauge butterfly needle (with
extension tubing) is preferred. A longer needle is not needed, and increases the chance of
inadvertently injecting deep to the neurovascular bundle. The needle is inserted toward
the palpated artery. When a flash is seen, insertion is continued until blood return ceases.
A <0.5ml volume is then injected to clear the hub/extension tubing and aspiration is
repeated to confirm position immediately behind the artery. The injection is then
performed in 5.0 ml increments, aspirating between injections to ensure that the correct
position has been maintained. When 5.0 ml remains, the needle is slowly withdrawn
through the artery, until blood return ceases. A <0.5ml volume is then injected to clear
the hub/tubing, and aspiration repeated to confirm position immediately superficial to the
artery. The last 5.0 ml is then injected, and the needle withdrawn. With volumes greater
than 30 ml, it is difficult to maintain position with the needle attached directly to the
syringe, and thus the butterfly type needle with attached tubing is helpful. A second
person can assist with the butterfly setup to handle the syringe, and this person is told
when to aspirate and inject by the primary operator. A single operator can use the
butterfly needle, and a small amount of blood will enter the extension tubing without
aspiration as the artery is penetrated.
Perivascular
The perivascular technique is performed with the same equipment as the transarterial, and
the same patient selection and education applies. Rather than penetrating the artery, the
artery is carefully localized, and the anesthetic injected at the same depth as the artery,
both superior, and inferior. When properly localized, the neurovascular sheath will
display the same sausage-like swelling post injection as is seen with the transarterial
method. The perivascular method can be guided by ultrasound, and the injected
anesthetic can be clearly seen as an enlarging hypoechoic area (see pitfalls, 4).
Anesthetic mixtures.
Several different anesthetic mixtures can be used, dependent upon the desired duration of
the block, and the patient involved (Table 1). Volume is more important to the success of
the block than concentration, and saline is commonly added to increase the volume as
needed. For a shorter acting block, 5.0 mg/kg of 1% lidocaine, diluted with equal volume
of normal saline (1:1 mixture) to a concentration of 0.5%. This mixture is 5.0 mg per ml.
and thus one ml per kg can be used. A maximum of 50.0 ml is generally considered
adequate in most adults (250 mg lidocaine). Duration of action is from 40-90 minutes.
Lidocaine with epinephrine can be used in the same volume and concentration, and this
will extend the duration, as well as providing an added dosage safety margin. Larger
volumes are sometimes used in the anesthesia literature, but the benefit of increasing
beyond 50 ml seems minimal. If longer duration is desired, a 1:1 mixture of 20 ml of
0.25% bupivicaine, and 20 ml of 1% lidocaine with epinephrine, increased with 10 ml
normal saline to a volume of 50.0 ml is used in larger adult (>50kg) patients. In smaller
adults/females (<50kg) a 1:1 mixture of 15 ml of 0.25% Bupivicaine, and 15.0 ml of 1%
lidocaine with epinephrine, diluted with 10cc of normal saline to a volume of 40.0 ml is
used.
The long lasting mixtures are also well suited to the patient who will be going from the
ED to the OR for further repair, and have become an increasingly frequent choice at our
institution.
Case Examples
Following are six representative cases from an ongoing prospective case series of axillary
blocks performed in the emergency department at our institution. In each case the
patient, and operator (person performing the ANB), were asked to “rate the pain of the
anesthetic procedure/injection on a 0-10 scale 0 being no pain, and 10 being the worst
pain you have ever felt. Both the patient and the operator (person performing the
reduction) were then asked to “rate the pain felt during the reduction/straightening of the
arm on a 0-10 scale.”
Case 1. A 15-year-old male presented to the ED with a significantly displaced, both
bone forearm fracture sustained in a fall. The patient appeared to be in considerable pain.
After neurovascular examination the axillary block was instilled. Twenty ml of 1.0 %
lidocaine with epinephrine, combined with twenty ml of 0.25% bupivicaine ( 40.0 ml
total) was used. Complete pain control at rest was achieved within one minute of the
injection. After return from x-ray the fracture was reduced to anatomic alignment under
fluoroscopy by orthopedics. Several forceful attempts by multiple persons were required.
The patient rated the pain of the injection 1/10, stating that there was actually no pain, but
that it felt “strange.” The operator rated the pain of injection 0/10, as there was no
objective sign of pain. Immediately following reduction the patient rated the pain of
reduction 0/10, saying that there was “no pain.” An orthopedic resident rated the pain of
reduction 0/10. The fracture later underwent ORIF as scheduled. Chart review showed
no complications.
Case 2. A 14-year-old male sustained a both bone forearm fracture by falling off a rope
swing. On presentation the patient appeared to be in moderate pain. After neurovascular
examination the axillary block was performed. Twenty cc of 1% lidocaine with
epinephrine, combined with 20 ml of 0.25% bupivicaine, and diluted with 10 ml Normal
Saline for a 50 ml total was used. Pain of injection was rated 0/10 by the patient, and by
the operator. The patient was pain free at rest within one minute of block completion.
After x-ray the fracture was reduced with moderate difficulty. Immediately following
reduction the patient rated the pain of reduction 0/10. The Emergency Medicine Resident
who performed the reduction also rated the pain of reduction 0/10. There was no
evidence of complications acutely, or per subsequent chart review.
Case 3. An 8 year-old male sustained a dorsally displaced distal radius fracture during a
fall from the monkey bars at his school. The patient appeared to be in significant
discomfort on arrival, and was apprehensive of needles. The patient did agree to a shot to
“Make the pain go away”, however, and tolerated the injection well. 16 ml of 1.0 %
lidocaine with epinephrine, diluted with an equal amount of normal saline was used.
When asked to rate the pain of injection the patient was unable to identify when the
injection had occurred, as he was not looking. A nursing observer rated the pain of
injection as 0/10, as the patient “didn’t seem to notice the injection.” Pain control was
apparent at 2 minutes post block, as the patient became talkative and began to move the
arm without discomfort. The reduction was done with the c-arm by an orthopedic
resident. Pain control was complete. The resident rated patient pain at 0/10. The patient
showed no sign of discomfort, and was very curious to see the x-rays on the fluoro.
monitor as the reduction occurred. The patient, when asked to rate the pain on a 0-10
scale after the cast had been placed stated that there “was, and is no pain.” Follow up visit
noted a 15 degree apex volar angulation, which was considered acceptable. There was no
evidence of complication acutely or per subsequent chart review.
Case 4. A 54 year old male presented with a distal radius fracture after falling backwards
out of a parked car. The patient had refused conscious or deep sedation, stating that; “It
took days for me to come out of it last time.” Neurovascular exam was intact. The patient
was diaphoretic and in moderate distress. An ANB was performed using twenty ml of 1
% lidocaine with epinephrine, combined with 20.0 ml of 0.25% bupivicaine and diluted
with 10.0 ml Normal Saline for a total volume of 50 ml. Pain of injection was rated 1/10
by the patient. The operator rated the pain of injection 0/10 as there was no visible sign of
pain. The patient was pain free within five minutes of the injection. The fracture was
reduced with difficulty, requiring repeated forceful manipulation. The patient rated pain
of reduction 0/10 saying; “I didn’t feel a thing.” The orthopedic resident who performed
the reduction rated the pain of reduction 0/10. There were no evident complications. The
patient returned 2 weeks later. He had missed his appointment with orthopedics and had
used his cast in a fight, “to defend himself”, breaking the cast in the process.
Neurovascular exam was intact at this time. No complications of the previous
anesthesia/reduction were apparent.
Case 5. A 55 year old male presented from an outlying facility with a splinted, dorsally
displaced distal radius fracture. Reduction by hematoma block had been attempted, but
had failed. The patient had refused a repeat hematoma block stating that it was “the most
painful experience of my life.” The patient agreed to undergo a “nerve block.” and was
consented. After neurovascular exam, twenty ml of 1.0 % lidocaine, 20.0 ml of 0.25%
bupivicaine, and 10.0 ml of normal saline was used. The patient rated the pain of
injection at 2/10. An observer rated the pain of injection at 1/10. Pain control at rest was
immediate, but the patient remained apprehensive. Complete distal motor blockade and
dense anesthesia of the fracture site occurred at twenty minutes post injection. The patient
seemed tense and winced several times during the reduction, which was difficult, and
required repeated attempts. The orthopedic resident rated the pain of reduction at 1/10.
The patient rated the pain of reduction at 2/10. When asked if he would have a “nerve
block” again he said yes, but added that some “happy juice” would be good, too. There
were no evident complications.
Case 6. A 76 year old female presented with a dorsally displace distal radius fracture
sustained during a ground level mechanical fall. The patient appeared to be in no distress
on arrival, with pain on movement only. Neurovascular exam was intact. The patient had
a complicated medical history including renal failure and diabetes. A block of short
duration was desired by the orthopedist. Fifteen ml of 1.0 % lidocaine with epinephrine
was combined with fifteen ml of plain lidocaine. Ten ml of normal saline was added for a
total volume of 40.0 ml. The patient rated the pain of the transarterial injection as 0/10, as
did a nurse observer. As the orthopedic resident was present at the time of the injection,
he wanted to perform the reduction as soon as possible. At seven minutes the resident felt
that the arm was ready for manipulation, as the patient showed no sign of pain when the
fracture site was gently moved. Splinting materials were readied and at 10 minutes the
arm was reduced. The orthopedist rated the pain of reduction at 0/10, as did the patient,
who showed no sign of discomfort. There were no acute complications. Chart review
showed good healing and no complications.
Discussion:
The axillary block was originally described by Dejong in 1961(1). This paper provides a
thorough discussion of anatomy and technique, and is highly recommended as
background reading. There are many techniques used to localize the neurovascular sheath
and these include the use of nerve stimulation, and elicitation of paresthesias. The
transarterial, and perivascular techniques, however, are similar in efficacy (6,8), far less
likely to cause nerve injury, and are thus safer, and less subject to criticism.
Forearm fractures can be anesthetized prior to reduction in several ways. The
transcortical anesthesia technique or “Hematoma Block” is commonly used. The
advantage of this technique is speed and simplicity. Disadvantages of this method include
pain as an 18 or 20 gauge needle is inserted into the fracture site, and potential risk of
infection, as a closed fracture is converted into an open one. Pain during reduction is also
frequently significant (see case 5 above) especially with difficult reductions, as skin
sensation generally remains intact.
The low dose “Bier Block”, is another method used by emergency physicians. (15) The
advantages of this technique include better anesthesia than the Hematoma Block and
fairly consistent efficacy. Disadvantages of this method include the need to place an I.V.
in the injured extremity, the need for nursing attendance to maintain the blood pressure
cuff, and the risks associated with accidental systemic administration of large doses of
local anesthetic. If the initial attempt at reduction fails, the block must be repeated before
another attempt. The shorter duration of the Bier Block prevents instillation before x-ray,
and manipulation for x-ray is therefore more painful. The I.V. must be removed before
application of a splint.
Procedural sedation is often used for the reduction of forearm fractures. Both moderate
and deep sedation are used safely and effectively by emergency physicians. Advantages
of procedural sedation include; availability of multiple agents with safe and effective
sedation profiles, and lack of operator dependency. Disadvantages include adverse drug
reactions, respiratory depression, aspiration, hypoxia, and other airway problems, delayed
recovery time, and the requirement of significant nursing resources.
Reduction without anesthesia may also be a viable option. Immediate reduction is
indicated if the trauma has caused a neurovascular compromise in the extremity. A dose
of medication IM may provide some pain control in these rare cases, and distracting the
patient may help.
The ANB is another option that can be used for upper extremity injuries. Advantages of
this technique include; minimal nursing support required, speed, simplicity, long duration
(allowing for repeat reductions/repeat x-rays if needed), and continued pain control in the
post reduction period. The ANB also provides muscular relaxation, which facilitates
fracture reduction. The technique is simple, and easily taught. It is comfortable for the
patient and extremely unlikely to cause a complication. The ANB can be performed
quickly, eliminating the need for an IV in most cases. Disadvantages include; a degree of
operator dependency, the inability to repeat the neurologic examination immediately after
reduction, and potential drug reactions.
When performed properly the ANB results in complete regional anesthesia, allowing an
absolutely pain free reduction in over 90 percent of cases (3,4,8,12) There is some
variability in the anatomy of the region, which results in the occasional incomplete
block. Good pain control at rest, however, is still generally achieved and this pain control
is nearly immediate. In the case of an incomplete block, the patient can be gently tested
for pain at the fracture site to determine if adequate anesthesia for reduction has been
achieved. Another regional technique such as a musculocutaneous nerve block (2) or
intravenous medication can be used to supplement if needed.
Pitfalls the author has observed in over 10 years of teaching the ANB include:
1.Infiltrating too deep.. As already noted, the neurovascular compartment is very
superficial . Even in an obese patient, a ¾ inch needle has always been long enough. In
the average patient you will not need the entire ¾ inch needle. If the needle is advanced
too far beyond the artery you will inject deep to the neurovascular compartment, and a
block will not be achieved. A recent study (23) emphasizes that using too long a needle
can decrease success rate significantly. The correctly performed injection into the
neurovascular compartment produces a “sausage like”, confined, subcutaneous swelling,
that is easily seen in all but the most obese patients (figure 4).
2. Using too small a volume of anesthetic. The ANB is a volume dependent technique. At
least 40.0 ml is needed to diffuse adequately in the adult patient. When using the
transarterial/perivascular techniques the objective is to fill the neurovascular
compartment with anesthetic that then diffuses into the nerves. An adequate volume is
required to both surround the nerves, and to move proximally far enough to reach the
musculocutaneous/ proximal nerves.
3. Attempting procedure too soon. Immediate rest pain control is generally achieved with
a properly placed injection. If a gentle manipulation is attempted immediately after the
block, however, some pain will still be felt. The person performing the reduction in this
case should be instructed to wait before performing the procedure. A significant number
of patients will be ready at five minutes, but the density of anesthesia will generally
increase for 20-30 minutes. In obvious fractures, the patient can receive the ANB prior
obtaining radiographs. The positioning required in radiology is thus less painful.
4. Not injecting proximally enough on the arm. The more proximally on the arm the ANB
is performed the more likely it will be complete. The musculocutaneous nerve has
already left the neurovascular bundle at the point where the injection is performed:
consequently, proximal placement of the anesthetic is required. When using ultrasound
to locate the neurovascular sheath it is important to inject proximally to the probe. There
is a tendency for physicians new to the ANB to place the probe proximal to the injection,
as the probe tends to rest stably in the axillary crease. This probe placement results in a
more distal injection, and a higher partial block rate.
In the case of an incomplete block, another regional technique can be used to supplement
the block(2). Moderate sedation can also be used in the case of an incomplete block and
the doses of these medications will usually be much lower than those normally needed to
provide good pain control during reduction.
Conclusion:
We described the use of the axillary nerve block in the ED. The ANB offers many
advantages for regional anesthesia. Its ease of use and clinical efficacy make it an
excellent option for pain control in forearm injuries. The ANB as described is a
surprisingly painless, highly effective, and simple technique that has withstood the test of
over 45 years of continued use. The methods which we use in the emergency department
are subject to continuous review and criticism, both by ourselves, and by many
physicians of other specialties. The ANB as discussed was perfected in such an
environment, and has much to recommend it for use by the emergency physician.
Figure 4-Finishing the injection
Figure 1-Placement of the partial venous tourniquet
Figure 2-Palpation and injection
Table 1-Axillary Block Anesthetic Doses
Duration
Drug
Short
Lidocaine 0.5% 5.0 mg/kg
<40 minutes
Dosing
Volume
Comments
Dilute 1.0 %
Use 40 ml for
1 ml per kg
lido 1:1 with
small adults
body weight
normal saline
<50kg
to maximum of
50 ml
Medium
Lidocaine 0.5% 5 mg/kg
Dilute 1% lido
Use 40 ml for
40-90 minute
with
1 ml per kg
1:1 with
small adults
epinephrine
body weight
normal saline
<50kg
to maximum of
50 ml
Long
Lidocaine 1.0%
20 ml
Dilute with
Use 15 ml
>90 minutes
with
lidocaine with
normal saline
Lidocaine/15 ml
epinephrine
epi.
to total of 50ml
Bupivicaine/10.0
Bupivicaine
0.25%
ml saline for
20 ml 0.25%
small adults
Bupivicaine
<50kg
Figure 3-The two operator technique
Figure 4) Sausage-like swelling of the neurovascular compartment after properly placed
injection
REFERENCES
1) Dejong, R. H. (1961). “(Axillary Block of the Brachial Plexus)” Anesthiology 22:
15-225
2){Dejong, R. H. (1965). "(Modified Axillary Block with Block of the Lateral
Antebrachial Cutaneous (Terminal Musculocutaneous) Nerve." Anesthesiology
26: 615-8.
3) Stan, T. C., M. A. Krantz, et al. (1995). "The incidence of neurovascular
complications following axillary brachial plexus block using a transarterial
approach. A prospective study of 1,000 consecutive patients." Reg Anesth 20(6):
486-92.
4) Pearce, H., D. Lindsay, et al. (1996). "Axillary brachial plexus block in two
hundred consecutive patients." Anaesth Intensive Care 24(4): 453-8.
5) Selander, D. (1987). "Axillary plexus block: paresthetic or perivascular."
Anesthesiology 66(6): 726-8.
6) Tuominen, M. K., M. T. Pitkanen, et al. (1987). "Quality of axillary brachial
plexus block. Comparison of success rate using perivascular and nerve
stimulator techniques." Anaesthesia 42(1): 20-2.
7) Johnson, P. Q. and M. A. Noffsinger (1991). "Hematoma block of distal
forearm fractures. Is it safe?" Orthop Rev 20(11): 977-9.
8) Winnie, A. P. (1995). "Does the transarterial technique of axillary block provide
a higher success rate and a lower complication rate than a paresthesia
technique? New evidence and old." Reg Anesth 20(6): 482-5.
9) Youssef, M. S. and D. A. Desgrand (1988). "Comparison of two methods of
axillary brachial plexus anaesthesia." Br J Anaesth 60(7): 841-4.
10) Wedel, D. J., J. S. Krohn, et al. (1991). "Brachial plexus anesthesia in
pediatric patients." Mayo Clin Proc 66(6): 583-8.
11) Wall, J. J. (1975). "Axillary nerve blocks." Am Fam Physician 11(5): 135-42.
12)Pearce, H., D. Lindsay, et al. (1996). "Axillary brachial plexus block in two
hundred consecutive patients." Anaesth Intensive Care 24(4): 453-8.
13) Serlo, W. and L. Haapanemi (1985). "Regional anaesthesia in paediatric
surgery." Acta Anaesthesiol Scand 29(3): 283-6.
14) Hoffmann, P., B. Schockenhoff, et al. (1983). "[Axillary blockade of the
axillary plexus in children]." Reg Anaesth 6(4): 86-7.
15) Mackay, C. A. and D. F. Bowden (1997). "Axillary brachial plexus block--an
underused technique in the accident and emergency department." J Accid Emerg
Med 14(4): 226-9.
16) Hickey, R., J. Hoffman, et al. (1993). "Comparison of the clinical efficacy of
three perivascular techniques for axillary brachial plexus block." Reg Anesth
18(6): 335-8.
17) McCarty, E. C., G. A. Mencio, et al. (1999). "Anesthesia and analgesia for the
ambulatory management of fractures in children." J Am Acad Orthop Surg 7(2):
81-91.
18) Margolis, J. O., A. K. Ross, et al. (1996). "Pediatric axillary block with
conscious sedation." Reg Anesth 21(6): 603-5.
19) Ting, P. L. and V. Sivagnanaratnam (1989). "Ultrasonographic study of the
spread of local anaesthetic during axillary brachial plexus block." Br J Anaesth
63(3): 326-9.
20) Reed, J. and S. Leighton (1994). "Ultrasound facilitation of brachial plexus
block." Anaesth Intensive Care 22(4): 499.
21) Selander, D., S. Edshage, et al. (1979). "Paresthesiae or no paresthesiae?
Nerve lesions after axillary blocks." Acta Anaesthesiol Scand 23(1): 27-33.
22) Schiller, M. G. (1976). "Intravenous regional anesthesia for closed treatment
of fractures and dislocations of the upper extremities." Clin Orthop(118): 25-9.
23) English, L. A., Holmes J. M. et al (2004). Effect of needle size on success of
transarterial axillary block.” AANA J. 72(1): 57-60
24) Kriwanek K.L., Wan J. Beaty J. H., Pershad J. (2006) “Axillary block for
analgesia during manipulation of forearm fractures in the pediatric emergency
department. A prospective randomized comparative trial.” Pediatric Orthopedics
26(6): 737-740