Overview of Upper Limb Block Anesthesia
Regional anesthesia, specifically the use of what’s called ‘peripheral nerve blocks’, is a way to numb a specific area for surgery, and to help control pain after the operation. This approach focuses on a certain body part which means you don’t experience unwanted side effects that you might get with other types of anesthesia. This method can also be a valuable part of a strategy to lessen the use of strong painkillers, known as opioids.
To do a peripheral nerve block, the medical provider will need the right equipment and a specific nerve structure to focus on. When selecting the numbing drug for the procedure, they consider the length of the surgery. Studies have shown that one of the most important factors for the success of this type of anesthesia is the total dosage of the numbing drug used. Several additional drugs can be used together with the numbing drug to speed up the start of numbness, extend the duration of the numbness, and enhance the quality of the numbness.
Anatomy and Physiology of Upper Limb Block Anesthesia
Understanding the structure of the brachial plexus, a network of nerves, is important to effectively numb the upper arm using anesthetic. The brachial plexus is formed by nerves coming from the spinal cord, specifically between the 5th cervical vertebra and the 1st thoracic vertebra. These nerves pass through two muscles in the neck and form three main “trunks”, namely, the upper, middle, and lower trunks.
These trunks travel over a specific rib and split into two divisions, the anterior and posterior, as they pass beneath the collarbone, or clavicle. Beyond the collarbone, these divisions merge to form three cords: the lateral, posterior, and medial cords. Each of these cords then branches out and eventually forms a final nerve.
When it comes to numbing an upper limb, or doing an “upper limb block”, the structure of the brachial plexus that needs to be targeted depends on what area needs numbing. Different areas need different blocks, specifically, an interscalene, supraclavicular, infraclavicular, or axillary block. Some parts of the upper limb, for example, the front of the shoulder which gets nerves from ‘superficial plexus’ or the outer network of nerves (from the 1st to the 4th cervical vertebra), might need extra separate blocks.
Why do People Need Upper Limb Block Anesthesia
Upper extremity peripheral nerve blocks are procedures used to stop pain during and after surgeries on the upper arm or forearm. Each type of nerve block is used for different kinds of surgery, based on where exactly the surgery is happening on your arm.
An interscalene nerve block is typically used for shoulder surgeries. However, it is not sufficient for surgeries that are past the elbow on the arm. A supraclavicular nerve block is usually more versatile and covers the whole arm. Infraclavicular and axillary nerve blocks are used for surgeries involving the elbow and those further down the arm, respectively.
If done correctly, none of the nerve blocks applied to the brachial plexus (a group of nerves that send signals from your spine to your shoulder, arm, and hand) will numb the upper inside part of your arm that’s closer to the elbow. To numb this area, a different kind of nerve block called an intercostobrachial nerve block needs to be added to the brachial plexus block.
When a Person Should Avoid Upper Limb Block Anesthesia
There are certain conditions under which a doctor would not provide a treatment called a peripheral nerve block. These treatments are aimed at numbing a specific area in the body to manage pain. However, a few circumstances may prevent this treatment including:
If the patient refuses the treatment or isn’t able to provide consent, doctors cannot go ahead.
If the patient has an issue with their blood that makes it hard for the blood to clot properly (a condition known as coagulopathy) or if they’re taking anticoagulants (medications to reduce blood clotting), the risk may be too high.
If there’s an ongoing infection, it’s not safe to do the procedure as it could spread the infection.
Lastly, if the patient has abnormal body structures that hide the normal path of the needle, it might be too tough or even impossible to aim for the right areas with the needle.
How is Upper Limb Block Anesthesia performed
The brachial plexus is a group of nerves that controls movement and sensation in the arm. Sometimes, doctors may need to numb these nerves for surgeries or procedures on the arm. The four main ways to do this are called the interscalene, supraclavicular, infraclavicular, and axillary nerve blocks.
The interscalene nerve block numbs the nerves closest to the neck and is mainly used for surgeries on the upper arm and shoulder. The patient’s head is turned away from the side being worked on. The doctor identifies the right nerves using an ultrasound, and then inserts a needle into the neck area. They inject a volume of local anesthetic, a medicine that numbs the area, to block the nerves. This method has some risks especially for patients with lung diseases, and may cause temporary paralysis of the diaphragm on the side of block or Horner’s syndrome (drooping of eyelid, constriction of pupil and loss of sweat on half of the face).
The supraclavicular nerve block numbs the nerves in the upper chest and provides anesthesia for most of the arm except the upper, inner part above the elbow. Similar to the interscalene block, the patient’s head is turned away from the side being worked on. With ultrasound guidance, the doctor uses a needle to inject the local anesthetic. The anesthetic should make the nerve area appear as if it’s floating on the ultrasound. Risks include phrenic nerve paralysis and Horner’s syndrome, but they are less frequent than with the interscalene block. There’s also a small risk of a collapsed lung, or pneumothorax.
The infraclavicular nerve block numbs the nerves under the collarbone and can provide numbness for the hand, forearm, elbow, and the outside of the upper arm. The doctor uses an ultrasound to guide the needle and inject the local anesthetic. Risks include a collapsed lung, blood collecting in the chest cavity (hemothorax), injury to nearby tissues, and a rare condition called chylothorax if the block is performed on the left side.
The axillary nerve block numbs the nerves in the armpit and is good for procedures on the forearm. Using an ultrasound for guidance, the doctor injects the local anesthetic. To fully numb the arm below the elbow, they might also need to block the musculocutaneous nerve, which is located in a muscle near the shoulder. Once the block is done, the arm should be numb and ready for the procedure.
Possible Complications of Upper Limb Block Anesthesia
Although it’s unusual, there can be complications when getting a peripheral nerve block, a type of treatment often used to reduce pain. Sometimes these treatments might not work as intended. Certain issues could be more likely depending on the specific area of the body being treated.
Here are some of the known complications that could occur with peripheral nerve blocks:
* Damage to the nerve root, which is where the nerves connect to the spinal cord.
* Experiencing paresthesias, which means you might feel tingling, pricking, or numbness in your skin.
* Having the anesthetic agent, or the medication that numbs pain, injected into the protective membranes surrounding your spinal nerves or your epidural space (the space outside the membrane that covers your spinal cord).
* Injuries to nearby areas, including blood vessels or muscles.
* Developing a pneumothorax, which occurs when air gets into the space between your lung and chest wall, causing your lung to collapse.
* Infections that could lead to an abscess, which is a pus-filled cavity.
* Experiencing local anesthetic toxicity. This means your body reacts negatively to the anesthetic, which can cause problems in your central nervous system (your brain and spinal cord) and your cardiovascular system (your heart and blood vessels).
What Else Should I Know About Upper Limb Block Anesthesia?
Using nerve blocks in upper extremity (arm and hand) surgeries can improve the effectiveness of general anesthesia and help manage pain both during and after the operation. These nerve blocks are specifically aimed at the brachial plexus – a group of nerves that run from the neck to the arm. This technique can lower the need for opioids, which are strong painkillers, during and after the operation. This is beneficial because opioids can lead to side effects such as slowed breathing, severe drowsiness, and nausea and vomiting.
It’s now standard practice to use ultrasound images as a guide when performing nerve blocks on different areas around the neck, collarbone, and shoulder (interscalene, supraclavicular, infraclavicular, and axillary blocks). Besides pain relief, this multimodal pain management – using a combination of different techniques – also helps to increase the satisfaction of both the patient and the surgeon.
