Overview of Brachial Plexus Block Techniques
A brachial plexus block is a type of anesthesia that numbs the whole arm, from the shoulder to the fingertips. The exact method used to administer this kind of anesthesia varies based on several factors, such as the reason for the procedure, the patient’s physical characteristics, their overall health, and the unique shape and positioning of their internal body structures. In this article, we will discuss five different techniques used to perform a brachial plexus block.
Studies have shown that brachial plexus blocks can manage postoperative pain more effectively than just using general anesthesia. Using a catheter to continuously deliver the block can reduce pain and the need for opioid painkillers even more in surgeries involving the upper extremity. That said, while this method can be more cost-effective, it’s only preferable if general anesthesia isn’t required as a backup option. The success and efficiency of the block largely hinge on its proper administration.
The precise placement of the needle is critical to the success of the block. The ultrasonic probe’s choice and positioning also heavily influence the process. It’s equally important to correctly identify the patient’s anatomy during the blocking. There are specific methods for the different types of blocks: the interscalene block, supraclavicular block, infraclavicular block, and axillary blocks.
The brachial plexus is comprised of several important structures: nerve roots, trunks, divisions, cords, and terminal branches. These structures are located on the spinal bones in the neck, and their visibility is dependent on the proper positioning of the probe. When we view these structures from the side, the nerve appears brighter on an ultrasound, while the surrounding tissues appear darker. Before giving the block, all these structures should be identified.
It’s crucial to identify blood vessels that run through or around nerve bundles during this procedure, to avoid damaging them. Using color Doppler techniques, a type of ultrasound that visualizes blood flow, can help us do this before the needle is inserted.
In conclusion, when brachial plexus blocks are correctly applied, they can greatly aid in reducing postoperative pain in surgery involving the upper extremity. However, having an accurate understanding of the patient’s ultrasound-based anatomy and carefully considering the best method for needle placement and avoiding blood vessels, are key to the safety and effectiveness of the procedure.
Anatomy and Physiology of Brachial Plexus Block Techniques
The brachial plexus is a network of nerves that runs from your spinal cord, in the area of your neck, down to your arm. These nerves are numbered from C5 to T1. They come together above your collarbone, forming three main nerve pathways, known as ‘trunks’. These trunks pass near the collarbone and can be quickly numbed at this location if needed. After the trunks pass the collarbone, they split into three ‘cords’, situated next to a large blood vessel in your armpit, known as the axillary artery. These cords then split again, forming the terminal nerves in your armpit, which control different movements and sensations in your arm.
The median nerve is created from two of the cords and is typically located on the surface level of the axillary artery. The ulnar nerve is created from one cord and is usually located on the outer side of the axillary artery. The radial nerve is located deep and towards the outer side of the axillary artery. Finally, the musculocutaneous nerve comes from one cord and cuts through a muscle near your armpit.
Different parts of the brachial plexus can be numbed for different effects, depending on the patient’s anatomy and the reasons for the procedure. Therefore, knowing multiple methods can be useful. There are various ways to numb or ‘block’ parts of the brachial plexus, including the Interscalene, Superior trunk, Supraclavicular, Infraclavicular, and Axillary methods.
The Interscalene block is the most commonly used. It numbs the shoulder, arm, and forearm by injecting a local anesthetic around the brachial plexus at the level of the nerve roots, which are located between certain neck muscles. The needle is inserted towards the neck until it comes into contact with bone.
The Supraclavicular block numbs the upper limb below the shoulder. It’s great for surgeries on the elbow and hand. This method involves inserting a needle just beside the collarbone. A local anesthetic is then injected around the brachial plexus near a large blood vessel.
The Infraclavicular block is used for procedures on the lower arm and hand. This method involves inserting a needle into a small dip near the shoulder blade, where a local anesthetic can be injected around the brachial plexus at its connection with the axillary artery. A different method for this block uses ultrasound to identify individual nerves within the upper armpit, allowing precise numbing of individual nerves or combinations.
Finally, the traditional Axillary block is also used for procedures on the lower arm and hand nerves. This method involves inserting a needle into the armpit in line with the arm bone, with a local anesthetic injected around the brachial plexus at its junction with the axillary artery.
Why do People Need Brachial Plexus Block Techniques
If you need to have a procedure on your upper arm or shoulder, doctors can use something called an interscalene brachial plexus block. This is a form of anesthesia – a medicine to numb part of your body so you don’t feel pain. This method is used to numb the area ranging from the collarbone to the top of the upper arm.
Doctors can also use a variant of this anesthesia called a superior trunk block. This is useful if they need to numb just the shoulder capsule and the top of the upper arm without affecting the phrenic nerve which controls the diaphragm (a muscle involved in breathing).
Supraclavicular brachial plexus block is another method doctors use to numb a larger area, from the middle of your upper arm all the way down to your fingertips.
An infraclavicular brachial plexus block works similarly to the supraclavicular block, numbing from the middle of the upper arm to the fingertips. However, with the infraclavicular block, a specific nerve (the intercostobrachial nerve) is usually left unaffected. There are different ways to perform this block, one of which involves a steep needle angle or a retroclavicular approach (RAPTIR).
Finally, an axillary brachial plexus block is another method to numb the area from the middle of your upper arm to your fingertips. However, with this technique, the intercostobrachial nerve is usually spared, but if needed, doctors can easily block it as well within the same procedure.
When a Person Should Avoid Brachial Plexus Block Techniques
There are certain circumstances in which brachial plexus blocks – a type of nerve block procedure used to decrease pain in the arms and shoulders – should not be done. This could be due to an active skin infection or a pus-filled area at the site where the injection is to be given, or if the patient is known to be allergic to the local anesthetic used in the procedure. Additionally, a patient also has the right to refuse the procedure.
Specific types of brachial plexus blocks may also have their own contraindications. For instance, interscalene brachial plexus blocks – a particular type of nerve block often used for shoulder surgery – should not be performed in patients with some types of lung and heart diseases. People with extreme obesity may also have to avoid this type of block as it could lead to breathing difficulties due to paralysis of one side of the diaphragm.
Just like interscalene blocks, superior trunk blocks also need to be avoided in certain situations, although the risk of phrenic nerve palsy (paralysis related to a specific nerve that controls breathing) is usually less. It’s also worth noting that the nerve that controls movement of the scapula, or shoulder blade, runs near the usual injection site.
Supraclavicular brachial plexus blocks – another type of nerve block for the arm – should be used carefully in patients with existing lung issues. This is because a complication like a collapsed lung (pneumothorax) could substantially worsen their breathing. For example, this would be a caution if the patient has a known lung infection on the opposite side.
Lastly, axillary brachial plexus blocks – yet another type of nerve block for the arm – should not be performed if the pathway of the needle through the blood-rich region is not clearly visible to the doctor.
Equipment used for Brachial Plexus Block Techniques
Regardless of the method used for the brachial plexus block (a type of nerve block in the shoulder), certain equipment is always needed. This includes:
A high-frequency (more than 10 MHz) linear ultrasound probe. This is kind of like a small scanner that the doctor uses to see the inside of your body clearly.
Chlorhexidine 2% or povidone-iodine skin disinfectant solution. This stuff is used to clean your skin before the procedure to prevent infection.
Local anesthetic; for longer duration blocks, doctors use either bupivacaine 0.5% or ropivacaine 0.5%; for shorter blocks, they use lidocaine 2% or mepivacaine 1.5%. This is medicine that makes the area numb, so you don’t feel any pain during the procedure.
A 10 mL to 20 mL syringe with extension tubing. This is what the doctor uses to inject the numbing medicine.
Short bevel block needle (10 cm, 18 to 22 G). This is a specific type of needle that’s used in the procedure.
Sterile ultrasound probe cover. This is a cover that ensures the ultrasound probe is clean and safe to use.
Sterile ultrasound gel. This gel helps the ultrasound probe to slide over your skin easily and helps the machine get a better picture of what’s inside your body.
Standard vital sign monitoring equipment (noninvasive blood pressure and rhythm monitoring, with or without pulse oximetry). This equipment helps the doctor track your vital signs like heart rate, blood pressure, and the level of oxygen in your blood, to make sure you’re safe during the procedure.
Who is needed to perform Brachial Plexus Block Techniques?
A medical professional who is skilled in using ultrasound to guide the giving of regional anesthesia is required. Other members of the healthcare team, such as a nurse or another healthcare provider, are also important. They will closely watch the patient’s condition and provide any necessary rescue medications. These are specific types of medicines used in emergencies to help the patient if something goes wrong.
Preparing for Brachial Plexus Block Techniques
Before your doctor performs what’s called a brachial plexus block, a type of nerve block, they will explain the risks, benefits, and alternatives to you. This is all part of the process before you give your informed consent, which means you understand and agree to the procedure. The area where the injection will be given is cleaned with a germ-killing solution like chlorhexidine 2% or povidone-iodine and is allowed to dry. A special sterile gel is applied to the probe, a device that helps the doctor guide the needle, and a sterile cover is put on it. Then, the right amount of local anesthetic, a medicine that numbs a specific area of your body, is put into a syringe. The syringe is connected to a tube with a needle attached. All the air is pushed out of this system, because air at the injection site can make it harder to see what’s happening with an ultrasound machine.
Depending on the specific location of your block – either interscalene, superior trunk, supraclavicular, and RAPTIR infraclavicular – you will be asked to lay flat on your back with your head and neck slightly turned to the opposite side. A roll of towel may be placed under your shoulder on the same side as the injection to create more space for the needle. Your arm on the same side should be kept by your side.
If you’re receiving a traditional infraclavicular or axillary block, similar to the other types, you’ll also be lying on your back with your head slightly turned away. Your shoulder on the side of the injection may be lifted to a right angle and your elbow bent. This helps your doctor see the axillary artery, a major blood vessel, more clearly and makes it easier to guide the needle.
How is Brachial Plexus Block Techniques performed
An interscalene brachial plexus block, superior trunk block, supraclavicular brachial plexus block, infraclavicular brachial plexus block, and axillary brachial plexus block are various procedures often used to numb the arm before surgery.
The principles of the techniques are similar. Certain areas of the arm are first identified using an ultrasound scan. Once these spots have been located, your doctor will inject a numbing medication using a needle.
In an interscalene brachial plexus block, the ultrasound scan helps find the brachial plexus – a network of nerves sending signals from your spine to your shoulder, arm, and hand – located in a groove in your neck. The numbing medication is then injected, typically ranging from 10 to 30 milliliters.
When doing a superior trunk block, the doctor will use the ultrasound to find where two nerve roots of the brachial plexus join to form the superior trunk. The medication is then injected into this area.
The supraclavicular brachial plexus block involves numbing the brachial plexus where it is located near the clavicle (collar bone). The injection is made where the brachial plexus overlies the first rib.
The infraclavicular brachial plexus block blocks patient feeling in the arm by numbing the area just below the clavicle. The medication is usually injected around the lower region of the axillary artery, a large blood vessel that travels through the armpit.
The axillary brachial plexus block uses ultrasound to scan the axilla (armpit) area where the nerves and blood vessels of the arm are located. The numbing medication is then injected into this region. Usually, about 20 to 30 milliliters of the numbing medication is needed to achieve the desired numbing effect.
Possible Complications of Brachial Plexus Block Techniques
When a patient undergoes a procedure involving a nerve block (a type of anesthesia that numbs a certain part of the body), there’s a small risk that it might cause temporary or even permanent damage to the nerves. This can happen because of accidental injection into the nerve itself, nerves reacting badly to the anesthesia, formation of a blood clot, or the needle used in the procedure causing harm. However, new research suggests that there’s no link between the type of brachial plexus block (a specific type of nerve block used for arm and hand procedures) and nerve injury.
The risk of the anesthesia spreading more than desired, causing toxicity, should also be kept in mind for all nerve blocks. Doctors are careful to keep the total dose of anesthesia injected below the potentially harmful limit for the patient.
There are a number of complications that can occur only with specific types of brachial plexus nerve blocks:
An ‘interscalene’ block can cause temporary paralysis in part of the lung on the side where the block was performed, vascular injury, a niche medical condition called Horner syndrome, a subdural block (a rare complication due to injection at the wrong site), and injuries to brachial plexus nerves (a network of nerves that sends signals from your spine to your shoulder, arm, and hand).
The ‘superior trunk’ block might also lead to temporary paralysis in part of the lung, though possibly less often than with the interscalene block. Other complications might include injuries to brachial plexus nerves and nearby blood vessels, or even nerves that aid in the movement of shoulder blades.
A ‘supraclavicular’ block poses significant risks of a pneumothorax (an unusual condition where air gets into the chest between the lung and the chest wall causing the lung to collapse) and puncturing a major artery. Temporary lung paralysis is also a possible complication but the risk is lower than an interscalene block. If the anesthesia doesn’t spread adequately, it may not numb the ulnar nerve (a nerve that runs near the ulna bone in the forearm) completely, causing discomfort.
There are certain risks associated with an ‘infraclavicular’ block as well, like injuring the brachial plexus, particularly certain parts of it, blood vessels in the armpit, and potentially leaving part of the block area without anesthetic cover if it doesn’t spread adequately around the axillary artery.
Lastly, an ‘axillary’ block carries virtually no risk of causing a pneumothorax. An ultrasound is recommended during the injection to avoid unintentionally puncturing a blood vessel, which could lead to toxicity from the local anesthesia.
What Else Should I Know About Brachial Plexus Block Techniques?
An ultrasound-guided ‘brachial plexus block’ – which is a type of numbing procedure – can provide intense pain relief to your upper extremity, from the shoulder to the fingers. The type of approach used depends on why the procedure is being done. The use of ultrasound has made this procedure safer and more approachable. Plus, studies have shown that using ultrasound also reduces the total amount of anesthetics needed, lowers risks like lung injury or damaging blood vessels, and improves the overall success of the procedure.
‘Interscalene brachial plexus blockade’, another type of numbing procedure, can be used to manage severe pain from fractures in the upper arm or collarbone, and to handle dislocated shoulders. It’s also effective for controlling pain after shoulder surgery, reducing the need for opioid pain medications. Some even use this as the only anesthetic during certain shoulder surgeries.
However, trying to numb the shoulder with an interscalene block comes with a high risk of causing one-sided paralysis of the diaphragm – a condition known as phrenic nerve palsy. If this is a concern, other methods like a superior trunk block or a combined suprascapular and axillary nerve block could be considered. Although the superior trunk block might not affect the diaphragm, more research is needed to confirm how effective it is.
There are several ways to block the brachial plexus – the nerve network providing sensation to the upper limb, further down from the ‘interscalene groove’ – a groove on the side of the neck. All these ways result in numbing the entire upper extremity from the mid-upper arm to the fingertips. The choice of approach depends on various factors like the patient’s ability to be positioned correctly, presence of infection at the injection site, and the doctor’s hands-on experience and understanding of nearby structures.
Combining suprascapular and axillary nerve blocks is an interesting alternative to regional anesthesia – numbing a larger region of the body – for shoulder surgery. This may be the preferred approach in patients with significant lung disease, those dealing with obstructive sleep apnea, or those with extreme obesity.
A recent extensive study compared supraclavicular, infraclavicular, and axillary blocks – all different methods of blocking the brachial plexus at varying locations – and found that all three methods are equally likely to succeed in numbing the upper extremity.