Infraclavicular Brachial Plexus Block Procedure

An infraclavicular block is a regional anesthesia technique that numbs the arm below the shoulder by depositing local anesthetic around the three cords of the brachial plexus just beneath the collarbone. It is one of several approaches to brachial plexus blockade, but it has gained particular traction with the spread of ultrasound guidance because the injection site sits away from the lung apex and phrenic nerve, giving it a safety edge over some neighboring techniques. The block reliably covers the elbow, forearm, wrist, and hand, making it a workhorse for a wide range of upper-limb surgeries.

Where the Needle Goes and Why It Matters

The brachial plexus reorganizes as it travels from the neck toward the arm. By the time it passes beneath the clavicle, the nerve roots have bundled into three cords named for their position relative to the axillary artery: lateral, posterior, and medial. An MRI study of 20 volunteers found that all three cords sit within about two centimeters of the artery, clustered in roughly two-thirds of a circle around it, with the ideal injection point being just above and behind the vessel.¹ That clustering is what makes a single deposit of local anesthetic capable of reaching all three cords at once, though the anatomy is not always textbook-perfect.

A large meta-analysis pooling data from over 4,700 upper limbs confirmed that major nerves branching from these cords follow their expected origins most of the time, but not universally. The musculocutaneous nerve arose in its textbook position in about 99% of cases, the ulnar nerve in roughly 98%, and the median nerve’s classic dual-root origin appeared in about 90%.² A separate cadaveric study found that close to half of dissected brachial plexuses showed at least one branching variation, many of them bilateral.³ These variations rarely cause block failure, but they explain why some patients end up with one nerve territory that takes longer to numb or requires supplementation.

How the Block Is Performed

With ultrasound, the practitioner places a probe below the clavicle, identifies the axillary artery and the cords surrounding it, and advances a needle to deposit local anesthetic in that space. The most common landmark-based approach historically was the coracoid (or paracoracoid) technique, where the needle enters the skin just medial to the coracoid process and angles toward the artery. A newer retroclavicular approach threads the needle behind the clavicle, which can make it easier to visualize on the screen. A trial comparing the two found that success rates were similar, but the retroclavicular path gave better needle visibility and required fewer passes, with patients reporting less discomfort during the procedure.⁴

Single Versus Multiple Injections

A longstanding question is whether you get a better block by depositing all the local anesthetic in one spot or by splitting it among the three cords. In the era before ultrasound, when nerve stimulators guided needle placement, splitting the dose made a clear difference. One trial from that era found that targeting each cord individually boosted the success rate from 40% to over 70% compared with a single stimulation.⁵

Ultrasound changed the calculus. When operators can see the anesthetic spreading in real time, a well-placed single injection behind the artery often does the job. One ultrasound-guided trial found complete sensory blockade in about 84% of single-injection patients versus 78% with triple injection at 15 minutes, a difference that was not statistically significant.⁶ Another study using a costoclavicular approach did find that triple injection produced a higher rate of complete four-nerve blockade at 30 minutes, but the overall anesthesia quality was similar between groups, and procedure time was virtually identical.⁷ In practice, many clinicians default to a single injection posterior to the artery and supplement only if a specific cord territory looks under-covered on ultrasound.

How It Stacks Up Against Supraclavicular and Axillary Blocks

The supraclavicular block, sometimes called the “spinal of the arm,” is the infraclavicular block’s closest competitor. Both target the brachial plexus in the clavicular region, and both cover the same downstream territory. A meta-analysis combining data from multiple randomized trials found that the infraclavicular approach produced a longer motor block and faster readiness for surgery, while sensory block duration, performance time, and onset speed were essentially the same between the two.⁸ A head-to-head trial confirmed similar success rates (around 93% for both) but reported faster sensory onset with the infraclavicular approach and, critically, fewer complications.⁹ That safety difference, particularly regarding the diaphragm and the lung, is the main reason some institutions now favor the infraclavicular route.

Another trial comparing ultrasound-guided supraclavicular and infraclavicular blocks found that the infraclavicular group had more patients ready for surgery at 20 and 30 minutes and a higher overall block effectiveness rate: 93% versus 78%.¹⁰ A review summarizing multiple comparative studies concluded that the infraclavicular approach showed slight advantages in both safety and block distribution.¹¹

Compared to the axillary block, which targets the plexus lower in the arm, the infraclavicular approach covers more territory. One randomized trial using nerve stimulator guidance found similar success rates (90% vs 87%), but the infraclavicular block was better at reaching the intercostobrachial nerve, which supplies sensation to the inner upper arm. That matters for procedures involving a tourniquet, because tourniquet pain tracks along that nerve.¹²

Diaphragm and Breathing Concerns

One of the most clinically meaningful advantages of the infraclavicular block is its low rate of phrenic nerve involvement. The phrenic nerve controls the diaphragm on its side, and blocks performed higher on the brachial plexus, especially interscalene and to a lesser extent supraclavicular, can temporarily paralyze half the diaphragm. For healthy people that is usually tolerable, but for patients with lung disease or limited respiratory reserve, it can be dangerous.

A randomized trial comparing ultrasound-guided supraclavicular and infraclavicular blocks found complete diaphragm paralysis in about a third of supraclavicular patients versus just 3% in the infraclavicular group.¹³ A separate trial confirmed a nearly identical pattern: diaphragm paralysis occurred in about 37% of supraclavicular cases but only about 3% with infraclavicular blocks.¹⁴ A study specifically testing a variation called the infraclavicular subomohyoid block as an alternative to a low-volume interscalene block found that the phrenic nerve was blocked in about 89% of the interscalene group but only 6% of the infraclavicular group, with no difference in pain relief or patient satisfaction.¹⁵

This diaphragm-sparing profile is one reason the infraclavicular block shows up in case reports involving patients with chronic obstructive pulmonary disease, where even temporary loss of half the diaphragm could trigger respiratory failure.¹⁶

Other Complications and Their Frequency

No nerve block is risk-free, and the infraclavicular approach has its own profile of potential problems. Vascular puncture is the most commonly reported complication, which makes sense given that the needle target sits right next to the axillary artery and vein. A narrative review tracking complication reports across multiple studies found vascular puncture rates ranging from about 2% to 10%, depending on the technique and the era. Early landmark-based series reported rates toward the higher end, while more recent ultrasound-guided techniques trend lower.¹⁷ A scoping review of adverse events in ultrasound-guided brachial plexus blocks confirmed that vascular puncture was more common with infraclavicular and axillary approaches than with supraclavicular blocks.¹⁸

Pneumothorax, the complication people worry about most with any near-the-chest nerve block, has become extremely rare with ultrasound guidance. A large prospective study tracked over 6,300 ultrasound-guided periclavicular blocks and identified only four cases of clinically symptomatic pneumothorax, a rate of 0.06%. Three of those cases did not manifest until two days later. By contrast, older landmark-based techniques had reported rates as high as 6%.¹⁹ The practical takeaway is that pneumothorax is not zero risk but is vanishingly uncommon when ultrasound is used properly.

Pain Control After Surgery

For surgeries on the forearm, wrist, and hand, an infraclavicular block provides substantial pain relief that outlasts the operating room. A randomized trial of patients undergoing distal radius fracture fixation found that those who received the block had significantly lower pain scores both at rest and with movement at every time point measured, from arrival in recovery through 48 hours, and consumed far less morphine.²⁰

One limitation of any single-shot block is that when it wears off, pain can surge. This phenomenon, sometimes called rebound pain, has prompted investigation into whether a continuous catheter or intravenous pain regimen can smooth the transition. A trial comparing a single infraclavicular block alone to the same block supplemented with either IV patient-controlled analgesia or a continuous infusion catheter found that pain scores at 9 and 12 hours after surgery were notably higher in the single-shot group. The continuous catheter group reported the lowest scores overall.²¹

Continuous Catheter Techniques for Home Recovery

The infraclavicular site is well suited to catheter placement because the anatomy holds the catheter relatively stable compared to more superficial or mobile locations. A continuous infraclavicular catheter delivers a steady trickle of local anesthetic through a thin tube left in place after the initial block, extending pain relief for days rather than hours.

A randomized trial of patients who took home an infraclavicular catheter pump after hand or arm surgery found that those receiving ropivacaine through the catheter reported average pain scores with movement of about 2.5 out of 10 on the first day after surgery, compared with roughly 6 out of 10 in the placebo group. Oral opioid use dropped in parallel: patients with ropivacaine averaged fewer than two tablets a day versus more than five in the placebo group.²² This approach has even enabled major procedures like total elbow replacement to be performed on an outpatient basis in selected patients, with the catheter managing pain at home for up to six days.²³

How Much Local Anesthetic Is Enough

Clinicians have traditionally used generous volumes for infraclavicular blocks, often 30 to 40 mL, but ultrasound guidance allows tighter placement and has pushed researchers to find the minimum effective dose. A study using 0.5% bupivacaine established the minimum effective volume at 14 mL for a single posterior-cord injection. Blocks performed at that volume still succeeded in all patients tested, though the onset was slower (about 40 minutes versus 15 minutes with 30 mL) and the duration of pain relief was shorter.²⁴ For ropivacaine at 0.75%, the minimum volume effective in half of patients was about 19 mL, but to cover 95% of patients the estimate climbed to around 31 mL.²⁵

The trade-off is intuitive: less drug means less toxicity risk and a faster recovery of motor function, but also a narrower margin for incomplete spread. Most practitioners settle on a middle-ground volume, say 20 to 25 mL, adjusting based on the patient’s size and whether the surgery demands a particularly dense block or a particularly fast offset.

Extending the Block With Dexamethasone

Adding dexamethasone to the local anesthetic mix or giving it intravenously at the time of the block is one of the most studied ways to prolong analgesia. A triple-arm randomized trial in supraclavicular blocks found that both perineural dexamethasone and an equivalent IV dose nearly doubled the duration of pain relief, from about 13 hours in the control group to roughly 25 hours in both dexamethasone groups.²⁶ Though that particular study examined supraclavicular blocks, the finding is widely applied across brachial plexus blocks, including infraclavicular ones, because the pharmacological principle is the same: dexamethasone reduces perineural inflammation and delays local anesthetic washout. The practical implication is meaningful. For patients going home after day surgery, the difference between 13 and 25 hours of pain relief can be the difference between sleeping through the first night and waking up in significant pain.

The Block in Patients With Obesity

Body habitus is a real consideration for infraclavicular blocks. The deeper tissue layers in patients with a higher body mass index can make ultrasound imaging murkier and needle trajectories steeper. A secondary analysis of a randomized trial confirmed that obese patients required about two additional minutes of procedure time on average, and needle visibility was frequently rated as difficult, requiring extra maneuvers to keep the tip in view.²⁷ A separate study found a moderate correlation between BMI and the steepness of the needle angle required, with about 39% of cases rated as having difficult needle visualization.²⁸

The encouraging part is that despite these technical challenges, block success and complication rates were not statistically different between obese and non-obese groups. The block works, it just takes a bit more patience and skill to place.

Artificial Intelligence and the Future of Image Guidance

One of the steepest parts of the learning curve for any ultrasound-guided nerve block is interpreting the image in real time. Recognizing arteries, veins, nerves, and fascial planes under a probe requires pattern recognition that takes time to develop. AI-powered software is beginning to change that. An accuracy study tested an AI system that overlays real-time labels on the ultrasound screen during peripheral nerve blocks, including infraclavicular blocks, performed by anesthesiology trainees. Once the software indicated it had identified all relevant anatomical landmarks, expert validators assessed the labeled images and confirmed that the AI successfully interpreted the structures.²⁹ This kind of tool does not replace an experienced clinician’s judgment, but it could meaningfully shorten the learning period for trainees and add a layer of confirmation for operators working in unfamiliar anatomy or on challenging body types.

More broadly, the trajectory of infraclavicular block practice over the past two decades has been shaped by ultrasound more than any other single factor. A comprehensive review noted that the biggest leaps in success rates and safety came not from new drugs or needle designs but from being able to see where the anesthetic goes.³⁰ AI-assisted imaging represents the next step in that same direction: making the visual information more accessible to more practitioners, in more clinical settings.