Infraclavicular Brachial Plexus Block
|
The boundaries of the infraclavicular fossa are the pectoralis minor and major muscles anteriorly, ribs medially, clavicle and the coracoid process superiorly, and humerus laterally. At this location, the brachial plexus is composed of cords. The sheath surrounding the plexus is delicate. It contains the subclavian/axillary artery and vein. Axillary and musculocutanous nerves leave the sheath at or before the coracoid process in 50% of patients. Consequently, the deltoid and biceps twitches should not be accepted as reliable signs of brachial plexus identification.
Anatomic structures of importance.
|
 |
A typical distribution of anesthesia after an infraclavicular brachial plexus block includes the hand, wrist, forearm, elbow, and distal arm. The skin of the axilla and proximal medial arm (unshaded areas) is not anesthetized (intercosobrachial and medium cutaneous brachii nerves).
|
|
|
|
The patient is in the supine position with the head facing away from the side to be blocked. The anesthesiologist also stands opposite to the side to be blocked to assume an ergonomic position during the block performance. It is best to keep the arm abducted and flexed in the elbow to keep the relationship of the landmarks to the brachial plexus constant. When a certain level of comfort with the technique is reached, the arm can be in any position during block performance. Attention should be paid when the arm is supported at the wrist to allow clear unobstructed detection of the twitches of the hand.
A standard regional anesthesia tray is prepared with the following equipment:
|
 |
Surface Landmarks
|
The following surface anatomy landmarks are useful in identifying the estimated site for an infraclavicular block:
|
 |
Anatomic Landmarks
|
Landmarks for the infraclavicular block include:
|
.jpg)
|
The needle insertion site is marked approximately 3cm caudal to the midpoint of landmark # 3.
|
An x-ray demonstrating the relevant anatomy:
|
TIP: Palpation of the bony prominence just medial to the shoulder, while the arm is elevated and lowered, identifies the coracoid process. As the arm is lowered, the coracoid process meets the fingers of the palpating hand. This maneuver should be used to identify the coracoid process in each patient planned for an infraclavicular block.
 |
 |
 |
Needle insertion
A 10-cm long, 22-gauge insulated needle, attached to a nerve stimulator, is inserted at a 45-degree angle to the skin and advanced parallel to the line connecting the medial clavicular head with the coracoid process. The nerve stimulator is initially set to deliver 1.5 mA. A local twitch of the pectoralis muscle is typically elicited as the needle is advanced beyond the subcutanous tissue. Once the pectoralis twitches disappear, the needle advancement should be slow and methodical while looking for the twitch of the brachial plexus.
TIPS:
- When the pectoralis twitch is absent despite appropriately deep needle insertion, the landmarks should be checked as the needle is most likely inserted too cranially (underneath the clavicle).
- The bevel of the needle should be facing down to facilitate nerve stimulation and reduce the risk of vascular puncture (subclavian or axillary artery and vein).
- Brachial plexus stimulation is typically obtained at a depth of 5 to 8 cm.
The goal is to achieve a hand twitch (preferably medianus) using a current of 0.2-0.3mA.
TIPS:
- Twitches from the biceps or deltoid muscles should not be accepted, since the musculocutaneous and axillary nerve, respectively, may depart the brachial sheath before the caracoid process.
- Hand stabilization and precision is crucial with this block as the sheath of the brachial plexus is very thin at this location and small movements of the needle may result in injection of local anesthetic outside the sheath. This in turn, results in a weak block with a slow onset.
- A twitch of the pectoralis muscle is observed first and indicates a too shallow placement of the needle. As contractions of the pectoralis muscle cease, the needle is slowly advanced until the twitches of the brachial plexus are elicited. This usually occurs at a depth of 5-8 cm.
- After the twitches of the pectoralis muscle cease, the stimulating current is lowered to below 1.0 mA to decrease patient discomfort. The needle is then slowly advanced or withdrawn until hand twitches are obtained at 0.2 - 0.3 mA.
- The success rate with this block decreases when local anesthetic is injected after obtaining stimulation with a current intensity above 0.3mA.
- In the absence of the medianus response, stimulation of the radialis or ulnar nerve can also be accepted, as long as the twitch of the hand is clearly visible.
- The twitch of the biceps (musculocutaneous nerve) or deltoid (axillary nerve) muscles should not be accepted as these nerves often leave the brachial plexus sheath proximal to the coracoid process.
Failure to obtain nerve stimulation on the first needle pass
When insertion of the needle does not result in brachial plexus stimulation, the following maneuvers should be undertaken:
- Keep the palpating hand in the same position, with the palpating finger firmly seated in the pectoralis and the skin between the fingers stretched.
- Withdraw the needle to the skin, redirect 10o cephalad, and repeat the procedure.
- Withdraw the needle from the skin, redirect 10o caudal, and repeat the procedure
|
|
|
|
|
TIPS
- When these maneuvers fail to result in motor response, withdraw the needle and assess the landmarks.
- Check that the nerve stimulator is properly connected and delivering the set stimulus.
- Consider inserting the needle 2-cm laterally and repeating the above steps.
Interpreting responses to nerve stimulation
Some common responses to nerve stimulation and the course of action to obtain the proper response.
| Stimulation | Motor Response | Explanation | Corrective Action |
| Pectoralis muscle - direct muscle stimulation | Arm adduction | Too shallow a placement of the needle | Continue advancing the needle |
| Latissimus dorsi | Arm adduction | Too deep a placement of the needle | Withdraw the needle to skin level and reinsert in another direction (superior/inferior) |
| Axillary nerve | Deltoid muscle | Needle placed too inferiorly | Withdraw the needle to skin level and reinsert with a superior orientation |
| Musculocutaneous nerve | Biceps twitch | Needle placed too superiorly | Withdraw the needle to skin level and reinsert with a light caudal orientation |
The infraclavicular brachial plexus requires a relatively large volume of local anesthetic to achieve anesthesia of the entire plexus. The choice of the type and concentration of local anesthetic should be based on whether the block is planned for surgical anesthesia or pain management. Due to the high vascular content of the area and potential for inadvertent intravascular injection, the local anesthetic solution should be injected slowly with frequent aspiration.
| Onset (min) |
Anesthesia (hrs) | Analgesia (hrs) | |
| 3% 2-chloroprocaine (+HCO3; + epi) | 5-10 | 1.5 | 2.0 |
| 1.5% Mepivacaine (+HCO3; + epi) | 5-15 | 2.5-4 | 3-6 |
| 2% lidocaine (+ HCO3 + epi) | 5-15 | 3-6 | 5-8 |
| 0.5% ropivacaine | 15-20 | 6-8 | 8-12 |
TIP: Always assess the risk-benefit ratio of using large volumes and concentrations of long-acting local anesthetic for a lumbar plexus block.
Adequate sedation and analgesia are crucially important for this block to ensure patient comfort and to facilitate interpretation of responses to nerve stimulation. For instance, midazolam 2-6mg IV can be used to achieve sedation. A short-acting narcotic (e.g., alfentantil 250-750 µg) is added just before needle insertion. A typical onset time for this block is 5-15 minutes, depending on the local anesthetic chosen. Waiting beyond 20 minutes will not result in further enhancement of the blockade. The first sign of the impending successful blockade is loss of muscle coordina-tion within minutes after the injection. This loss can be tested easily by asking the patient to touch his nose, while paying attention that the patient does not miss the nose and injure his/her eye. The loss of motor coordination typically occurs before sensory blockade can be documented. In case of inadequate skin anesthesia despite the apparent timely onset of the blockade, local infiltration at the site of the incision by the surgeon is often all that is needed to allow the surgery to proceed. Before and after the surgery, both the patient and the surgeons should be informed about the expected duration of the blockade.
| Hematoma |
- Avoid multiple needle insertions through the pectoralis muscle - Apply firm pressure over the site of needle insertion after needle withdrawal - Carefully review indications for the single shot and avoid continuous infraclavicular block in patients with abnormal coagulation |
| Systemic Toxicity |
- Limit the volume/dose of long-acting local anesthetic - Carefully review risks and benefits of using long-acting local anesthetics for each and every patient/operation - Inject local anesthetic with frequent aspiration to rule out intravascular injection, carefully assessing the patient for signs of local anesthetic toxicity - Inject local anesthetic SLOWLY to avoid "channeling" of local anesthetic to smaller veins/lymphatic channels that may have been punctured during needle advancement |
| Nerve Injury |
- Use the nerve stimulator to confirm the needle position! This technique requires deep needle insertion and the use of paresthesia is not acceptable - Make sure that the nerve stimulator is fully functional and connected properly - Advance the needle slowly when the twitches of the pectoralis muscle cease - Orient the bevel of the needle down to facilitate nerve stimulation and avoid contact of the plexus complements (and vascular walls) with the advancing tip of the needle - Do not inject against high pressures! In this scenario, withdraw the needle, check its patency by flushing it, and repeat the procedure - Stop injecting immediately when patients complain of pain on injection! |
| Pneumothorax |
- This is an often feared but exceedingly rare complication - The needle direction is actually away from the chest cavity (as opposed to interscalene or supraclavicular blocks) - Attention should be paid to the site and angle of needle insertion to ensure that the needle assumes a plane away from the chest wall |
- Brown DL, Bridenbaugh LD: The Upper Extremity. Somatic Block . In Cousins, M.J., and Bridenbaugh PO (eds): Neuronal Blockade in Clinical Anesthesia and Management of Pain. Philadelphia, J.B. Lippincott-Raven Publishers, 1988, pp 345-71
- Greher M, Retzl G, Niel P, Kamolz L, Marhofer P, Kapral S: Ultrasonographic assessment of topographic anatomy in volunteers suggests a modification of the infraclavicular vertical brachial plexus block. Br J Anaesth 2002; 88:632-6
- Hadzic A, Vloka JD, Kuroda MM, Koorn R, Birnbach DJ: The practice of peripheral nerve blocks in the United States: a national survey. Reg Anesth Pain 1998; 23:241-6
- Ilfeld BM, Morey TE, Enneking FK: Continuous infraclavicular brachial plexus block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study. Anesthesiology 2002; 96:1297-304
- Koscielniak-Nielsen ZJ, Rotboll Nielsen P, Risby Mortensen C: A comparison of coracoid and axillary approaches to the brachial plexus. Acta Anaesthesiol Scand 2000; 44:274-9
- Klaastad O, Lilleas FG, Rotnes JS, Breivik H, Fosse E: Magnetic resonance imaging demonstrates lack of precision in needle placement by the infraclavicular brachial plexus block described by Raj et al. Anesth Analg 1999; 88:593-8
- Maurer K, Ekatodramis G, Rentsch K, Borgeat A: Interscalene and infraclavicular block for bilateral distal radius fracture. Anesth Analg 2002; 94: 450-2
- Rodriguez J, Barcena M, Rodriguez V, Aneiros F, Alvarez J: Infraclavicular brachial plexus block effects on respiratory function and extent of the block. Reg Anesth Pain Med 1998; 23:564-8
- Raj PP: Infraclavicular approaches to brachial plexus Anesthesia. Techniques in Reg Anesth and Pain Management 1997; 1:169-77
- Raj PP, Pai U, Rawal N: Techniques of regional anesthesia in adults. In Clinical Practice of Regional Anesthesia Edited by Raj New York, Churchill Livingstone, 1991, pp 276-300
- Whiffler K: Coracoid block--a safe and easy technique. Br J Anaesth 1981; 53:845-8
- Wilson JL, Brown DL, Wong GY, Ehman RL, Cahill DR: Infraclavicular brachial plexus block: parasagittal anatomy important to the coracoid technique. Anesth Analg 1998; 87:870-3
