Distal radius fractures (commonly called Colles’ or Smith’s fractures) are often encountered in the emergency department, with options for analgesia revolving around either a hematoma block, intravenous opioids, or procedural sedation, particularly for closed reduction. A novel single-injection nerve block technique known as the retroclavicular approach to the infraclavicular region (RAPTIR) may be the ideal method for excellent pain control, allowing for nearly painless closed reduction and lasting analgesia.^1,2

Clinical Conundrum

There are many locations to block the brachial plexus as it emerges from the cervical column and then travels down the neck, underneath the clavicle, and into the arm. In our 10-year ED-clinical experience, blocks of the proximal portion of the brachial plexus (superior to the clavicle) offer better analgesia for injuries to proximal structures (ie, shoulder and upper arm), whereas blocks of the distal portion of the brachial plexus (inferior to the clavicle) offer better analgesia for distal structures (ie, elbow, forearm, wrist, and hand). Unfortunately, when performing brachial plexus blocks above the clavicle, we have noticed inconsistent analgesia for distal radius fractures.

The upper extremity regional blocks that most emergency physicians may be familiar with include the interscalene and supraclavicular blocks.³ However, both of these blocks target the proximal portion of the plexus. They provide excellent analgesia to the shoulder and upper arm, but they commonly fail to provide analgesia adequate for closed reduction of distal radius fractures. Also, when placing anesthetic in locations adjacent to the phrenic nerve, there is concern for ipsilateral diaphragmatic paralysis.

Performing a block in the distal region of the brachial plexus, specifically below the clavicle, maximizes distal upper extremity anesthesia while minimizing phrenic nerve blockade. The classic blocks in this region include the infraclavicular block (ICB) in the chest wall above the axilla and the axillary block (AXB) on the medial aspect of the upper arm at the axilla. Unfortunately, these blocks historically have been difficult to perform for two reasons.

First, when performing a traditional ICB with the patient in the position of comfort (shoulder adducted, elbow flexed, and the fractured wrist resting at their side or on their chest/abdomen), the clavicle forces the operator to enter the skin at a very steep angle, significantly decreasing ultrasound visualization of the needle tip during the procedure and increasing the risk of iatrogenic pneumothorax. Second, in order to bring the brachial plexus out from under the clavicle, these blocks are commonly performed with significant upper extremity manipulation. Directly following an injury, abducting and externally rotating the shoulder is often not possible, limiting the generalizability of these infraclavicular approaches to the brachial plexus.

RAPTIR is a novel block that targets the same distal portion of the brachial plexus while correcting for the major challenges associated with traditional ICB and AXB. The patient is allowed to remain in the position of comfort during the procedure, and the needle angle is kept flat relative to the ultrasound probe, markedly increasing needle tip visualization and avoiding a trajectory deep into the thoracic cavity. Additionally, the needle path avoids the nearby cephalic vein and thoracoacromial artery, and only one injection is required to block the entire distal extremity.

We have successfully performed the RAPTIR in numerous patients in our emergency department, facilitating dense anesthesia and ideal pain control for closed reductions. When compared to procedural sedation, we have noted two specific benefits from using the RAPTIR. First, when attempting to optimize closed reduction (and potentially avoid subsequent open reduction and internal fixation), we often require repeat radiographs to confirm proper alignment. RAPTIR allows for essentially painless repeat reduction attempts (if needed) without worry of a prolonged sedation. Second, because we use a long-acting anesthetic for the block, patients can be sent home with excellent pain control, starting an oral analgesic before the block wears off.

Figure 1: Overview of the initial and final probe position when performing the block. Slide the transducer (blue solid line) from mid-clavicle region to the deltopectoral groove. The probe marker (green dot) should face cephalad. The goal is to visualize the subclavian/axillary artery as it exits below the clavicle.
Credit: Luftig,  Mantuani, Nagdev

 

Figure 2: Stand above the patient with the ultrasound screen in clear view. Note the transducer is located in the deltopectoral groove with the needle entering above the clavicle.
Credit: Luftig, Mantuani, Nagdev

Procedure

Visit www.highlandultrasound.com/raptir for a video demonstration of this technique.

Pre-assessment: Patients with a short, poorly mobile neck; thick chest wall; or deformed clavicle, such as from prior fracture, are poor candidates for RAPTIR, and another technique should be considered. We recommend a pre-block survey scan to determine if the axillary artery is clearly visible (see Figure 1).

Positioning: Place the patient in a semi-recumbent supine position with the affected extremity adducted in a position of comfort. Rotate the patient’s head away from the injured limb and put a folded blanket under the upper back (ipsilateral to the injury). Stand at the head of the bed with the ultrasound system in direct line of sight (on the same side as the injured extremity) (see Figure 2).

Survey scan: Place a high-frequency linear transducer in the infraclavicular region with the cephalad portion of the probe resting on the medial portion of the clavicle (see Figure 3A). The transducer should be in parasagittal orientation with the probe marker facing cephalad. Slide the transducer laterally along the inferior portion of the clavicle (see Figure 3B). While sliding laterally, sonographically visualize the axillary artery in cross section as it emerges from under the clavicle (see Figure 3C), traverses the second rib, then courses away from the thoracic cage, appearing on ultrasound to be moving farther and farther from the clavicle. Fix the probe at the position where the axillary artery is 2–3 cm from the clavicle on the ultrasound (see Figure 3D). At this location, rotate the probe slightly to aim towards the axilla and identify the injection target, which lies just posterior to the artery.

Figure 3A: The ultrasound probe is placed in the initial position (1) with the probe marker facing cephalad. 3B: Slide the ultrasound transducer along the inferior aspect of the clavicle until close to the deltopectoral groove (2). 3C: Note that in the initial position (1) the axillary artery (Ax) may be visible just under the clavicle (C). 3D: In the second position (2), the axillary artery (Ax) is visible and away from the pleura.
Credit: Luftig, Mantuani, Nagdev

Anesthetic: For a 70 kg patient, use 35–40 mL of 0.25% bupivacaine, 0.5% ropivacaine, or 1% lidocaine with epinephrine. Always adhere to weight-based local anesthetic dosing guidelines.

Needle type: Use a Tuohy 20g, 90 mm epidural needle (block needle) and a 25–27g hypodermic needle (for the local anesthetic skin wheal needle).

Injection setup: We commonly use a two-person technique to perform this block. One operator is advancing the needle under ultrasound visualization with the second operator slowly injecting the anesthetic while frequently aspirating to prevent inadvertent vascular puncture.

Injection: The primary challenge of the RAPTIR is passing the block needle through the “blind zone” created by the acoustic shadow of the clavicle during the initial portion of needle insertion. Keeping the transducer fixed over the injection target and aligned aiming towards the axilla, identify a block needle insertion site aligned with the long axis of the ultrasound beam and approximately 2 cm cephalad to the clavicle (see Figure 4A). This will ensure a safe needle path and allow adequate room for the needle to clear the posterior surface of the clavicle without angling posteriorly. Probing the insertion site with a gloved finger and seeing transmitted tissue motion on the ultrasound view help the operator get a feel for the needle insertion path and help determine if the insertion site is posterior enough to clear the clavicle.

Figure 4A: A flat needle angle will be used to traverse under the clavicle (C). 4B: The bock needle will have to pass under the clavicle and will not be visualized. Note the needle tip as it emerges from under the clavicle and can be easily seen because of its flat angle. 4C: The block needle is advanced until placed just under the axillary artery (Ax). 4D: Anechoic anesthetic fluid is injected under the axillary artery (Ax) for a successful block.
Credit: Luftig, Mantuani, Nagdev

Place a local anesthetic skin wheal at the insertion site using a 25–27g needle, then insert the block needle through the skin wheal and advance the needle beneath the clavicle toward the ultrasound beam at an angle parallel to the gurney (see Figure 4A). The patient should be prompted to alert the operator of any paresthesia in the shoulder while the needle advances, as the suprascapular nerve lies in the vicinity; this is a very uncommon occurrence. If the patient reports paresthesia of the shoulder, the needle should be withdrawn, and a slightly different needle path should be used. Also, when passing through the blind zone created by the clavicle, the needle should never be angled posteriorly, as this increases the risk of pneumothorax. However, the entire needle can be posteriorly deflected by applying pressure to the shaft at the insertion site while maintaining the same flat angle of approach, similar to the method used to get past the clavicle for a blind subclavian central line.

After insertion through the approximately 3 cm blind zone, use subtle needle and transducer adjustments to locate the clearly visualized needle emerging from beneath the clavicle (see Figure 4B). Continue advancing with in-plane ultrasound guidance toward the target location just posterior to the axillary artery, typically at or slightly past the six o’clock position relative to the artery (see Figure 4C). Aspirate to check for inadvertent vascular puncture and then inject small aliquots of normal saline. Anechoic anesthetic fluid should be seen spreading just posterior to the axillary artery and deflecting the artery toward the probe, confirming needle tip location within the axillary sheath (see Figure 4D). The sheath surrounds both the brachial plexus and the axillary artery. Thus, fluid injected into the sheath bathes the plexus. It is not necessary to visualize the nerves of the plexus. Once satisfied with the needle position, gradually inject local anesthetic until a total of 35–40 mL is deposited within the sheath. Total needling time is usually less than five minutes, and dense arm anesthesia develops within 30.

Mr. Luftig is a PA in the department of emergency medicine at Highland General Hospital.

Dr. Mantuani is assistant director of emergency ultrasound at Highland General Hospital.

Dr. Nagdev is director of emergency ultrasound at Highland General Hospital in Oakland, California.

References

1. Luftig J, Mantuani D, Herring AA, et al. Ultrasound-guided retroclavicular approach infraclavicular brachial plexus block for upper extremity emergency procedures. Am J Emerg Med. 2017;35(5):773-777.
2. Charbonneau J, Fréchette Y, Sansoucy Y, et al. The ultrasound-guided retroclavicular block: a prospective feasibility study. Reg Anesth Pain Med. 2015;40(5):605-609.
3. Herring AA. Bringing ultrasound-guided regional anesthesia to emergency medicine. AEM Educ Train. 2017;1(2):165-168.