Overview of Supraclavicular Block
A supraclavicular block is a method used to numb the upper part of the arm (from the middle of the upper arm to the hand). It’s often used instead of, or in addition to, general anesthesia for surgeries on this area. It can also be used to help manage pain after surgery. This technique was first introduced in 1911 but initially it was less popular due to a risk of pneumothorax, which is a condition where air gets into the space between the lung and the chest wall, causing the lung to collapse.
With the development of ultrasound technology, it became safer to use this block. In fact, in 1978, La Grange used a Doppler probe (a special ultrasound tool) to help locate the arteries for the block. Further, a group of doctors led by Kapral recommended using ultrasound to guide the placement of the needle for the block. This makes the procedure more accurate and safe.
Sometimes referred to as the “spinal of the arm,” the supraclavicular block is beneficial because the nerves of the arm (brachial plexus nerves) are closely packed together in this area. Therefore, the numbing effect is often achieved quickly. However, caution is needed in the amount of local anesthesia used because too much can lead to compression ischemia, a condition where blood flow to the arm can be cut off due to pressure.
Anatomy and Physiology of Supraclavicular Block
The brachial plexus is a network of nerves that run from the fifth to the first thoracic vertebrae of the spine (C5 to T1). These nerves then leave the neck and divide into three primary bundles or “trunks” that move between two muscles in the neck known as the anterior and middle scalene muscles. Each of these trunks splits into front (anterior) and back (posterior) branches, which then come back together to form bundles called lateral, posterior, and medial cords, which are located nearer to the collarbone (clavicle).
In a procedure called a supraclavicular approach, these nerves are blocked starting from the farthest trunks to the closer cords. However, the target is often towards where the trunks divide. This is typically done for surgeries or procedures that require numbing part of the arm. This numbing effect allows surgery or other treatments to be carried out without you feeling any discomfort or pain.
Why do People Need Supraclavicular Block
A supraclavicular block is a type of local anesthesia used for operations, or for managing pain after surgery. It is specifically used for the lower two-thirds of the arm, or from the middle of the upper arm to the fingertips. However, it might not be as effective for the very tips of your hand, especially the side which is controlled by the ulnar nerve (a major nerve that runs down your arm).
When a Person Should Avoid Supraclavicular Block
There are several reasons why a person may not be able to receive a specific type of nerve block known as a supraclavicular block. These reasons could include the patient not wanting the procedure, being allergic to local anesthetics (numbing medications), having an infection or cancer where the needle will enter, and having a disease that makes their blood not clot well.
When a doctor decides to perform a supraclavicular block, they will need to follow the guidelines set by the American Society for Regional Anesthesia and Pain Medicine. This block is considered a deep block site, which means it’s a procedure where possible bleeding would be difficult to control.
If a patient is on blood thinners (anticoagulation therapy), the doctor might instead want to consider a more superficial (closer to the skin surface) brachial plexus block – another type of nerve block. The doctor would also need to be extra careful in patients with severe lung diseases. This is because the anesthesia can sometimes spread and weaken the diaphragm (the main breathing muscle), or cause a pneumothorax (collapsed lung), though this is less likely with the use of ultrasound during the procedure.
Lastly, if a patient already has nerve problems in the area where the block is meant to take effect, a regional block would not be recommended.
Equipment used for Supraclavicular Block
Here’s a list of what your doctor will need for your procedure:
* Chlorhexidine gluconate or povidone iodine: These are types of antiseptics, used to clean your skin and prevent infection.
* A high-frequency ultrasound probe with sterile probe cover and gel: This tool helps the doctor get a clear image of what’s happening inside your body.
* Nerve stimulator (optional): This device can be used to test the function of nerves and muscles.
* Local anesthetic, typically 1% lidocaine: This is a medicine used to numb a small area of your body, so you won’t feel pain during the procedure.
* Regional block local anesthetic solution (0.5% bupivacaine or 0.5% ropivacaine for postoperative pain relief, and 2% lidocaine or 1.5% mepivacaine when the anaesthetic needs to start working quickly): This is a stronger anaesthetic used to numb a larger area or part of your body.
* 10 to 20 mL syringe with extension tubing: This is used to inject the anesthetic.
* Short bevel block needle (10 cm, 18 gauge for continuous catheter or 22 gauge for single-injection): This is the needle used to deliver the injection.
Who is needed to perform Supraclavicular Block?
It’s best if the person who puts you to sleep during surgery, called an anesthesiologist, is trained in a special skill – ultrasound-guided regional anesthesia. This is a technique where they use ultrasound technology to help numb only a specific region of your body. Other members of the healthcare team, like nurses who have special training in anesthesia, might also help during your operation.
Preparing for Supraclavicular Block
Before carrying out a procedure, your healthcare provider needs to obtain your informed consent. This means that they will explain the process to you, answer any questions you may have, and ensure you understand and agree with everything that’s going to happen. Once this is completed, a brief pause is taken to prepare for the procedure.
After this, you will be asked to lie flat on your back with your arms by your sides. Your head will be turned to the side opposite of where the procedure will be done. In some cases, the head of the bed might be raised slightly, or a towel roll might be placed under your shoulder to provide better access for the healthcare provider.
To help you relax and possibly reduce discomfort, you may be given a small dose of medication through an intravenous line (often shortened to “IV”), which is a tube inserted into one of your veins. However, some patients might not need this step.
To ensure cleanliness and avoid infection, your healthcare provider will follow a careful routine known as aseptic technique. This involves cleaning the skin with a special solution and using sterile equipment. In this case, the solution may be chlorhexidine gluconate 2% or povidone-iodine, and a sterile gel will be applied to an ultrasound probe, which is a device used for viewing inside the body. It is usually recommended to cover this probe with a sterile cover for maximum cleanliness.
How is Supraclavicular Block performed
The ultrasound device is positioned above the collarbone and directed towards the chest on the same side. Images are generated that show the bundle of nerves known as the brachial plexus and the subclavian artery (a major artery in the chest). The first rib also becomes visible as a very bright or ‘hyperechoic’ line. Beneath this rib, the lining or pleura of the lungs can be seen.
For this procedure, a needle is inserted and guided from the outside to the inside, towards the main cluster of nerves in the brachial plexus. After checking that the needle is not inside a blood vessel (this is called negative aspiration), the doctor injects a local anesthetic, which is a medicine that causes numbness or loss of feeling in the area (around 10 mL). Additional small amounts of this medicine are then injected into the nearby, smaller nerve clusters.
One alternative technique is the “corner pocket” method. This also uses a needle, but it first aims towards the deeper part of the brachial plexus and lifts the cluster of nerves off the first rib using the flow of the anesthetic solution. Then the needle is moved back and advanced at a shallow angle, aiming towards the superficial or upper part of the brachial plexus. After checking for negative aspiration, the local anesthetic (about 10 mL) is injected. However, bear in mind that this method may have a higher chance of puncturing the lining of the lungs.
Sometimes, nerve stimulation is added to the ultrasound to help guide the process. If this is used, the nerve stimulator is set up before the local anesthetic is injected. If the arm, forearm, or wrist twitches when the stimulator is set below 0.4 mA, it’s likely that the needle is inside one of the nerves. If so, the needle will be pulled back and redirected. Doctors also recommend monitoring the pressure of the injection during these types of nerve-blocking procedures. This is because too high pressure (15 psi or more) can mean that the needle is closer to the nerves or even inside them.
Possible Complications of Supraclavicular Block
Supraclavicular blocks, a type of peripheral nerve blockade, can sometimes have complications. These can include risks of infection, bleeding, and a condition known as neuropathy which affects the nerves. However, the risk of certain complications, like a lung getting punctured (pneumothorax), can be reduced by using a method called ultrasonography. This method allows doctors to constantly watch the needle tip, first rib, and an area known as the pleura.
Just like other proximal brachial plexus blockades, there could be some temporary side effects. These might include a hoarseness in your voice due to a block in a nerve going to the voice box (laryngeal nerve), a condition called Horner syndrome from a block in a cluster of nerve cells (stellate ganglion), and weakness on one side of your diaphragm (known as hemidiaphragmatic paresis) due to a block in the phrenic nerve.
Moreover, there’s a possibility of experiencing toxic effects from the local anesthetic used. Also, it’s worth mentioning that the transverse cervical and dorsal scapular arteries are located very close to the brachial plexus. This is the reason why the use of color Doppler, a type of ultrasonography that shows blood flow, is recommended during this procedure.
What Else Should I Know About Supraclavicular Block?
Supraclavicular block is a type of medical procedure that’s used to numb a part of your body before a surgical operation. This technique is typically performed using ultrasound guidance on the so-called “brachial plexus”, a network of nerves that send signals from your brain to your shoulder, arm, and hand. Because these nerves are closely packed together, using a supraclavicular block can produce quick and potent sensory and motor anesthesia. This means it can greatly reduce the pain from a surgical procedure.
It’s possible to use a supraclavicular block for shoulder surgery, but this would require additional measures to numb the upper cervical nerves in your shoulder.
Ultrasound guidance has made the supraclavicular block safer by allowing doctors to avoid puncturing the lung (pleura). Studies have shown that the procedure takes roughly 4 minutes and can provide pain relief for up to 437 minutes after surgery. Additional perks include decreased risk of inadvertent lung puncture or damage to blood vessels. This block technique is usually performed successfully regardless of whether the patient can move their arm or not.
The choice between different techniques to numb upper extremities before a surgery – such as the supraclavicular, infraclavicular, interscalene, and axillary blocks – will depend on many factors. Your doctor will consider the location of the surgery, their expertise, anatomical variations between patients, the risk of blood clot formation, presence of infection at the intended site of the block, ability to comfortably position the patient, and whether the block is mainly aimed at providing anesthesia during the operation or pain relief after it.
Research comparing the effectiveness of these different techniques showed similar results for operations below the shoulders. Comparatively, supraclavicular blocks have been shown to result in lower rates of hoarseness and Horner syndrome, a condition that can cause a drooping eyelid and change to pupil size, compared to interscalene blocks.