Anesthesia for surgery of the hand

Question 1

Describe the relevant anatomy for upper extremity brachial plexus blocks.

Answer 1

The brachial plexus is formed by the anterior primary divisions of the fifth to eighth cervical nerves and the first
thoracic nerve, with frequent contributions from the fourth cervical and second thoracic nerves (Fig. 117-1). The
cervical nerve roots reorganize into superior, middle, and inferior brachial plexus trunks. The trunks undergo a
separation into anterior and posterior divisions. As these divisions enter the axilla, they give way to cords, now
oriented as the lateral, medial, and posterior cords. At the lateral border of the pectoralis minor muscle, the three
cords reorganize to give rise to the peripheral nerves of the upper extremity. These include the musculocutaneous,
median, ulnar, and radial nerves.

Question 2

What is the concept of “plexus anesthesia”?

Answer 2

The concept of “plexus anesthesia” provides a system of single-injection techniques for blocking the brachial plexus.
The concept is based on the fact that a fascial envelope, which extends continuously from the intervertebral foramina
to the distal axilla, invests the brachial plexus. This fascial sheath may be entered with a single injection of a local
anesthetic, and the extent of anesthesia that develops depends on the level of injection and the volume of local
anesthetic injected at that level.

Question 3

What parts of the brachial plexus are anesthetized by the interscalene, subclavian
perivascular, infraclavicular, and axillary techniques of brachial plexus block?

Answer 3

The interscalene block anesthetizes the roots, the subclavian perivascular block the trunks, the infraclavicular block the
cords, and the axillary technique the terminal nerves of the brachial plexus.

Question 4

What is the interscalene groove, and how is it located?

Answer 4

The interscalene groove is the groove located between the anterior and middle scalene muscles. The block needle is
inserted in this groove at the level of C6 (which is determined by extending a line laterally from the cricoid cartilage)
when performing an interscalene or subclavian perivascular block. To locate this groove, the patient is placed in the
supine position with the head turned opposite to the side to be blocked. The patient is instructed to raise his/her head
slightly to make the sternocleidomastoid muscle prominent. The anesthesiologist then palpates the posterior border of
the sternocleidomastoid muscle and asks the patient to relax. The palpating fingers are rolled laterally across the belly of
the sternocleidomastoid muscle until the interscalene groove is located.

Question 5

Although the block needle enters the interscalene groove for both the interscalene
and subclavian perivascular blocks, the needle direction differs for the two blocks.
Describe the needle direction for each.

Answer 5

For the interscalene block, the block needle is inserted in the interscalene groove in a direction that is perpendicular to
the skin in every plane, with a slight caudad direction. For the subclavian perivascular block, the block needle is inserted
in the interscalene groove in a directly caudad direction.

Question 6

How is the correct location of the needle in the interscalene or subclavian
perivascular space identified?

Answer 6

Elicitation of a paresthesia in the distribution of the brachial plexus roots (interscalene block) or trunks (subclavian
perivascular block) indicates the correct needle position within the brachial plexus fascia. The patient may describe the
paresthesia as an electric shock sensation in the arm or hand. A nerve stimulator may also be used to identify correct
needle placement. With this technique, the negative terminal of the nerve stimulator is attached to the block needle and
the positive electrode is attached to an electrode on the side of the chest opposite to the arm that is being anesthetized.
The needle is advanced until a muscle contraction in the arm or hand identifies the part of the brachial plexus being
stimulated. The needle is then advanced until the maximal contraction is identified.

Question 7

Besides the subclavian perivascular and interscalene blocks, what other brachial
plexus blocks are performed above the clavicle? Describe how these blocks are
performed.

Answer 7

The classic supraclavicular block and a modification of this block, the so-called “plumb bob” technique, are also
performed above the clavicle. In the classic supraclavicular block, the midpoint of the clavicle is identified and the
needle is introduced posterior to the subclavian artery in a caudad direction until bone is encountered. The needle is
systematically walked anteriorly and posteriorly along the rib until a paresthesia is elicited, indicating that the brachial
plexus has been located. In the “plumb bob” technique, the block needle is introduced at the point at which the lateral
border of the sternocleidomastoid muscle inserts into the clavicle. It is introduced in a posterior direction (toward the
floor in a supine patient), and, if necessary, the needle can be rotated in small steps through an arc of approximately 30°
in a more cephalad or caudad direction, following the line of insertion that a plumb bob would generate (Fig. 117-2).

Question 8

How is an infraclavicular block done?

Answer 8

The needle is inserted 2 cm below the midpoint of the inferior clavicular border and is advanced laterally. Marking a line
between the C6 tubercle and the brachial artery through the midclavicle with the arm abducted is helpful in visualizing
the course of the plexus and the needle direction. This block requires a longer needle than with the other techniques
because it is introduced in a location more distant from the brachial plexus.

Question 9

What other techniques of infraclavicular block are described, and how are they
performed?

Answer 9

One approach identifies the midpoint of a line drawn between the jugular notch and the ventral apophysis of the
acromion. The needle is introduced beneath the clavicle in a posterior direction. A modification of this technique, known
as the coracoid approach, uses the coracoid process (located by placing two fingers in the groove between the deltoid
and pectoralis major muscles, and gently palpating laterally) as a landmark. In this technique, the needle is inserted
2 cm medial and 2 cm caudad to the coracoid process and is advanced posteriorly.

Question 10

Describe the axillary technique of brachial plexus block.

Answer 10

For an axillary block, the patient is placed in the supine position with the arm abducted to 90° and the forearm flexed,
with the dorsum of the hand lying on the table next to the patient’s head. The axillary artery is palpated and followed
proximally until it disappears under the pectoralis major muscle. With the index finger over the pulse, the brachial plexus sheath is penetrated with the block needle and the needle is advanced until one of four endpoints is achieved.
(1) A distinctive click is felt as the needle penetrates the brachial plexus sheath, with the short bevel of the block needle
contributing to the perception of the click. (2) A paresthesia is elicited in the distribution of the median, radial, or ulnar
nerves. (3) Arterial blood is aspirated indicating puncture of the axillary artery. When arterial blood is aspirated, the block
needle may be advanced and the injection made behind the artery, or alternatively half of the local anesthetic can be
injected behind the artery and half injected after withdrawing the needle to the front of the artery. (4) A nerve stimulator
can be used to localize nerves within the axillary sheath. The specific muscle twitch response that is elicited identifies
the nerve being stimulated. A contraction of an appropriate muscle group in the hand or forearm at a current of 0.5 A or
less indicates proper placement of the block needle within the brachial plexus sheath.

Question 11

Besides a nerve stimulator, what additional tool is being used to facilitate placement
of brachial plexus blocks?

Answer 11

Ultrasound is now gaining momentum among many to facilitate placement of brachial plexus blocks. This technique can
help identify vascular and neural structures and may make our techniques more predictable.

Question 12

What is the “multiple compartment” concept?

Answer 12

Some authors (Thompson and Rorie) have described the presence of septae extending inward from the brachial plexus
sheath, which create multiple compartments around the neurovascular bundle. These septae inhibit the spread of local
anesthetic when it is deposited in a single injection technique (as popularized by Winnie). However, other authors
have not observed septae or have found them to be thin and incomplete.

Question 13

What is the advantage of using a catheter technique for brachial plexus block, and
how is it done?

Answer 13

The insertion of a catheter allows repeated injections of local anesthetic for long surgical procedures. In addition,
continuous infusions of analgesic concentrations of local anesthetic may be continued for postoperative pain relief.
A blunt tip needle and catheter set (Contiplex) can be used, with identification of a “fascial click” to signify entrance into
the brachial plexus sheath. The proper position of the catheter can be tested by injecting 2 to 4 mL of cold (refrigerated,
4°C to 6°C) normal saline through the catheter. This will elicit a short but distinct cold paresthesia into the arm and/or
hand, indicating correct position of the catheter. Alternatively, paresthesia or nerve stimulator techniques can be used to
identify correct placement of the advancing needle.

Question 14

What determines the choice of local anesthetic for brachial plexus block?

Answer 14

The local anesthetic is chosen based on the desired duration of anesthesia, the necessity of motor block, and
any history of local anesthetic allergy. Lidocaine and mepivacaine are useful for outpatient surgical procedures
when the desired duration of surgical anesthesia is 2 hours or less. For longer procedures, bupivacaine 0.5%
or ropivacaine 0.5% may be used. The addition of epinephrine in a concentration of 1:200,000 is useful in prolonging the duration of local anesthetic action. It is also useful for early detection of an intravascular injection, which
is particularly beneficial in a technique such as the transarterial technique of axillary block, in which the axillary
artery is deliberately punctured. Bupivacaine, or the newer local anesthetic ropivacaine, is useful for long
procedures (when greater than 4 hours of surgical anesthesia is necessary) or when prolonged postoperative
anesthesia is desirable.

Question 15

What is ropivacaine, and what is its advantage over bupivacaine?

Answer 15

Ropivacaine and 5-bupivacaine are the only local anesthetics prepared as the pure s-isomer rather than a racemic
mixture. Toxicity studies show that ropivacaine is less cardiotoxic than bupivacaine, although ropivacaine still possesses
some dysrhythmogenic potential. In a concentration of 0.5%, it is an effective agent for brachial plexus block with an
onset and duration similar to bupivacaine. Both are long-acting agents that produce profound sensory and motor block.

Question 16

What is the purpose of “alkalinization” of a local anesthetic?

Answer 16

Alkalinization of local anesthetics has been used to improve onset time and with brachial plexus blocks has produced
conflicting results. The principle is that raising the pH increases the percentage of the local anesthetic present in the
nonionized free base form. It is this form that crosses the nerve cell membrane to reach the site of action of local
anesthetics.

Question 17

What are some potential complications associated with interscalene block?

Answer 17

Some of the main complications of interscalene block include subarachnoid injection, epidural injection, injection into
the vertebral artery, pneumothorax, cervical sympathetic block (Horner’s syndrome), recurrent laryngeal nerve block
(hoarseness), and phrenic nerve block. Complications that may occur with each technique of brachial plexus block
include local anesthetic overdose, allergic reaction to the local anesthetic, intravascular injection, hematoma formation,
and nerve trauma.

Question 18

What is the mechanism of phrenic nerve block, how can it be diagnosed, and how
common is it following interscalene block?

Answer 18

Phrenic nerve block may result from diffusion of local anesthetic cephalad to involve the more proximal cervical roots
(C3, C4, and C5) or may be a consequence of an improperly performed block with local anesthetic deposited outside the
brachial plexus sheath, anterior to the anterior scalene muscle. Ultrasonography or conventional x-ray technique may
diagnose it. One study noted a 100% incidence of ipsilateral hemidiaphragmatic paresis diagnosed by ultrasonography
in a group of patients receiving interscalene blocks. Although generally no treatment is required for phrenic nerve block,
decreases in pulmonary function (approximately 25% decrease in forced vital capacity and forced expiratory reserve
volume at 1 second) do occur. Therefore interscalene blocks should be avoided in patients who cannot tolerate this
reduction in pulmonary function, particularly patients in whom the opposite hemidiaphragm is already paralyzed.

Question 19

How is injection into the vertebral artery and epidural or subarachnoid spaces
avoided with an interscalene block?

Answer 19

Careful aspiration prior to injection and a slight caudad needle direction lessens the likelihood of inadvertent vertebral
artery, epidural, or subarachnoid injection

Question 20

If the subclavian artery is punctured when performing a subclavian perivascular
block, the block needle should be redirected in which direction to locate the brachial
plexus trunks?

Answer 20

The needle should be redirected more dorsally because the subclavian artery lies anterior to the trunks of the
brachial plexus.

Question 21

How is the risk of pneumothorax minimized when performing a subclavian
perivascular block?

Answer 21

The principal cause of this complication is a needle direction that drifts medially toward the cupula of the lung; thus this
direction should be avoided.

Question 22

How is a pneumothorax treated if it develops as a complication of interscalene or
subclavian perivascular brachial plexus block?

Answer 22

If the pneumothorax is small, the patient can be given oxygen and observed, provided positive pressure ventilation does
not have to be initiated for general anesthesia with a failed block. If the pneumothorax is larger than 20%, aspiration
through a small-gauge catheter followed by patient observation often is all that is necessary. Rarely, a chest tube is
required for reexpansion of the lung.

Question 23

What nerve distribution is frequently missed when an interscalene block is performed?

Answer 23

The ulnar nerve distribution may be difficult to anesthetize with an interscalene block because the block is performed at
the level of C6, which is cephalad to the derivation of the ulnar nerve (C8-T1).

Question 24

Name some advantages of axillary block compared with interscalene or subclavian
perivascular block.

Answer 24

An axillary block is performed remote from the neck and thorax; thus the site-related complications of blocks carried out
above the clavicle are avoided. These include cervical sympathetic block, phrenic nerve block, recurrent laryngeal nerve
block, and vertebral, epidural, and subarachnoid injection. The location of the nerves of the brachial plexus is superficial
in the axilla, leading to relatively easy identification of anatomic landmarks. One disadvantage of axillary block is that
the volume of local anesthetic required is larger than for an interscalene or subclavian perivascular block.

Question 25

25. What nerves are frequently missed with an axillary block and why?

Answer 25

The musculocutaneous nerve is frequently missed with an axillary block because the musculocutaneous nerve leaves the brachial plexus high in the axilla, which may be proximal to the insertion of the block needle. Thus the local anesthetic may not reach the nerve, particularly if a low-volume technique is used. If block of the musculocutaneous nerve is necessary, a separate injection is made by reinserting the needle superior to the axillary artery and injecting 5 to 8 mL of local anesthetic into the substance of the coracobrachialis muscle. The intercostobrachial nerve is derived from T2, which is not a part of the brachial plexus and must be blocked separately. This nerve is blocked by a subcutaneous skin wheal superficial to the axillary artery pulse, from the anterior to the posterior axillary fold. This injection also blocks the medial brachial cutaneous nerve, which also leaves the brachial plexus high in the axilla. Block of the intercostobrachial and medial brachial cutaneous nerves provides analgesia of the upper, inner aspect of the arm and allows the more comfortable use of a pneumatic tourniquet.

Question 26

If a postoperative nerve deficit develops and you suspect it may have been caused by the anesthetic, what should be done?

Answer 26

A careful neurologic examination should be performed and its results documented. An electromyogram (EMG), if done within 3 weeks of the injury, may be helpful in establishing preexisting pathology if there is evidence of denervation of muscles. The EMG should be repeated 3 weeks after the block and surgery. If a patient had a normal preoperative study or a normal EMG soon after surgery but developed an abnormal EMG 3 weeks after the performance of the block, then the block or surgical procedure (related to the procedure itself or other incident at the time of surgery, such as improper positioning or tourniquet use) may be the cause of the nerve damage.

Question 27

Describe how the ulnar, median, and radial nerves can be blocked around the elbow.

Answer 27

The ulnar nerve is blocked behind the medial epicondyle, where it is palpable, using a 1.5-cm, 25-gauge needle and 5 mL of the local anesthetic agent. Avoid impaling the nerve on the bone to prevent damage to the nerve. The median nerve is blocked by introducing a 3.8-cm, 22-gauge short-beveled needle medial to the artery, slightly above the level of a line drawn between the epicondyles. The nerve is identified by paresthesias or by using a nerve stimulator and 5 to 10 mL of local anesthetic is injected. The radial nerve is blocked 3 to 4 cm above the lateral epicondyle, where it is close to the distal humerus, after piercing the lateral intermuscular septum. A 3.8-cm, 22-gauge needle is introduced at this level, and 5 to 10 mL of local anesthetic is injected after the nerve is identified by paresthesias or by use of a nerve stimulator.

Question 28

WRIST BLOCKS

Answer 28

The median nerve is blocked by inserting a 1.5-cm, 25-gauge needle between the palmaris longus and the flexor carpi radialis tendons at the level of the ulnar styloid process or the proximal crease of the wrist. In the absence of the palmaris longus, the needle is inserted on the ulnar side of the flexor carpi radialis tendon. After a paresthesia is obtained, 5 mL of local anesthetic is injected, taking care to inject the local anesthetic around the nerve rather than directly within the substance of the nerve. The ulnar nerve is blocked by inserting a 1.5-cm, 25-gauge needle at the level of the proximal crease of the wrist, just radial to the flexor carpi ulnaris tendon, which is made prominent by active flexion of the wrist. After obtaining a paresthesia, 5 mL of local anesthetic is injected, again taking care not to inject directly within the substance of the nerve. The dorsal cutaneous nerve can be blocked by subcutaneous infiltration of approximately 5 mL of local anesthetic beginning at the site where the ulnar nerve was blocked and extending the infiltration to the midpoint of the dorsum of the wrist. The superficial branch of the radial nerve is blocked by a subcutaneous infiltration starting radial to the radial artery and extending around to the midpoint of the dorsum of the wrist, using 5 to 7 mL of local anesthetic.

Question 29

How can a digital block be obtained?

Answer 29

A volar approach can be used in which a skin wheal is made directly over the flexor tendon just proximal to the distal palmar crease, and 2 to 3 mL of local anesthetic without epinephrine is injected on each side of the flexor tendons where the digital neurovascular bundles are located. In the dorsal approach, which is a less painful method of blocking the digital nerves, the needle is inserted to the side of the extensor tendon, just proximal to the web. A skin wheal is made, and 1 mL of local anesthetic is injected superficial to the extensor hood to block the dorsal nerve. The needle is advanced toward the palm until its tip is palpable beneath the volar skin at the base of the finger, just distal to the web. Another 1 mL of local anesthetic is injected here to block the volar digital nerve. Before the needle is removed, it is redirected across the extensor tendon to the opposite side of the finger, and a small skin wheal is made overlying the other dorsal digital nerve. The needle is then withdrawn and reintroduced into the skin wheal on the opposite side of the finger, and the same technique is repeated. Care should be taken with this technique to use small amounts of local anesthetic to avoid creating a circumferential ring block, which can result in vascular impairment of the digit.

Question 30

Why should a ring block for anesthetizing a digit be avoided?

Answer 30

A circumferential block around the base of the digit can result in compartment syndrome producing gangrene, even if no vasopressor drug has been added to the local anesthetic.

Question 31

Describe the technique for performing a Bier block.

Answer 31

A dual tourniquet is placed on the upper arm of the side to be blocked. An intravenous line is placed with a 20-gauge plastic cannula and a heparin lock attached. The arm is elevated and exsanguinated with an Esmarch bandage, starting from the fingers all the way up to the tourniquet. The proximal tourniquet is inflated, and the Esmarch bandage is removed. The local anesthetic is slowly injected through the cannula. Lidocaine (3 mg/kg given as 0.5% without preservative) provides anesthesia within 4 to 6 minutes and lasts as long as the tourniquet is inflated. The proximal tourniquet is left inflated for 20 minutes or until the patient notices some discomfort. The distal tourniquet is inflated, and, when its inflation is confirmed, the proximal tourniquet is deflated. Because the distal tourniquet is applied over an anesthetized area, the patient is not likely to experience any discomfort for approximately 40 minutes. At the completion of the surgical procedure, the tourniquet is deflated for 15 seconds, reinflated for 30 seconds, and deflated again, especially if the duration of anesthesia was 20 minutes or less. If the procedure lasts longer than 40 minutes, the tourniquet can be safely deflated without reinflation.

Question 32

What are the advantages of a Bier block?

Answer 32

easy to perform and is suitable for outpatient surgery. Bilateral blocks can be done safely. Rapid return of motor function enables the surgeon to evaluate the results of the procedure.

Question 33

List some disadvantages of the Bier block technique

Answer 33

** Tourniquet Pain. Even with use of the double cuff, pain due to the tourniquet limits use of this procedure in operations lasting more than 1 hour. ** Problems with Tourniquet Release. When the tourniquet is released, a large bolus of anesthetic enters the systemic circulation. This brief elevation of local anesthetic blood level may produce systemic toxic reactions, including convulsions and cardiac irregularities. The longer the tourniquet remains inflated, the lower the anesthetic blood level. If the cuff is released for 15 seconds, reinflated, and then released again, it will lower the peak blood level and decrease the possibility of systemic reaction. However, if the tourniquet pressure is decreased gradually, when it reaches a pressure below arterial pressure and above venous pressure, local anesthetic enters the circulation producing toxic blood levels. ** Loss of Anesthesia after Cuff Deflation. If the surgeon wants to attain hemostasis and then close the wound, there is only 5 to 10 minutes of postdeflation analgesia, which may be inadequate in some procedures. ** Equipment Problems. Equipment must be tested and the tourniquet calibrated prior to use. Once the tourniquet is inflated, the local anesthetic is injected only after the absence of the radial pulse is confirmed. If the proximal and distal cuffs are not properly identified and labeled as such, tourniquet pain is likely to be a problem. Constant vigilance is necessary to ensure that the equipment is in working order and to avoid accidental disconnection and deflation of the cuff.