Overview of Transversus Abdominis Plane Block
The increasing number of side effects and deaths due to opioids has led to the exploration of alternative ways to manage pain. The use of ultrasound-guided regional anesthesia, a technique that numbs a specific area of the body, is on the rise, especially for managing acute, or sharp and sudden, pain. This increase is linked to the growing availability of ultrasound machines.
One common area of pain after abdominal surgery is the abdominal wall itself. With the help of ultrasound technology, a technique known as a transversus abdominis plane (TAP) block can provide effective relief for this specific type of pain. A TAP block is a procedure in which an anesthetic, a medication that numbs pain, is carefully injected into an area in the abdomen to block pain signals.
Incorporating TAP blocks into a comprehensive pain management plan can be very beneficial. However, they may not provide adequate relief for visceral pain, which is pain coming from the internal organs. Therefore, additional pain relief methods may be necessary.
The Transversus Abdominis Plane (TAP) is a space located between two muscles in the abdomen, namely the transversus abdominis and the internal oblique muscles. In a TAP block, local anesthetic is injected into this space, creating a wide area of pain relief. This is also known as a “field block.”
Anatomy and Physiology of Transversus Abdominis Plane Block
The front and side of your belly is known as the anterolateral abdominal wall. The area is bordered by different parts of your body: to the side by the back armpit lines, above by the rib cage and lower breastbone, and below by the hip bone, groin ligament, and pubic bone. The muscles in this area are the external oblique, internal oblique, and transversus abdominis, sorted from outermost to innermost.
There’s a layer between the transversus abdominis muscle and the internal oblique muscle called the TAP or transverso abdominis plane. The nerves supplying this area are mostly the thoracoabdominal ilioinguinal and iliohypogastric nerves, which form the upper and lower TAP network. In order to numb the entire abdominal wall during medical procedures, several injections need to be given to target the nerves from T6-L1.
The T6-T12 nerves enter the TAP from different locations. The T6-T9 nerves can be numbed below the rib cage as they only enter the TAP towards the front, while the T10-T12 nerves enter more to the side and can be numbed between the lower rib cage and the top of the hip bone.
A single TAP block, a type of nerve block injection, usually provides pain relief to one section of the abdominal wall. To block the L1 segment, an injection has to be given towards the front of the hip bone. However, a common limitation of TAP block is that it can only relieve body pain and not internal organ pain.
The transversus abdominis muscle and the internal oblique muscle become thinner towards the back, blending into the thoracolumbar fascia—a wide band of connective tissue. This fascia covers the quadratus lumborum and erector spinae back muscles. The external oblique muscle ends at the back, next to the latissimus dorsi muscle. The three abdominal wall muscles—external, internal, and transversus abdominis muscles—join together in the middle. Their tendon-like extensions form the rectus sheath, a fibrous layer of tissue covering the rectus abdominis muscle. Below the transversus abdominis muscle, there’s a thin tendon-like membrane called the transversalis fascia, which is sandwiched between the muscle and the peritoneum—the lining of the abdominal cavity.
Why do People Need Transversus Abdominis Plane Block
A transversus abdominis plane (TAP) block is a type of anesthesia that numbs a specific area of the abdomen to ease pain during and after specific surgeries. TAP blocks are commonly recommended for:
* Major operations in the abdomen
* Surgeries involving the colon and rectum
* Repairs of hernias, which are bulges in the body where an organ, like the intestine, pushes through a weak spot in the muscle or tissue
* Procedures that involve the wall of the abdomen
* Cesarean sections, which is a surgical procedure to deliver a baby through a cut made in the mother’s abdomen and uterus.
When a Person Should Avoid Transversus Abdominis Plane Block
There are several reasons why a TAP block, a type of anesthesia often used in abdominal surgeries, might not be suitable for a patient:
– If a patient doesn’t want to have a TAP block, this would rule it out.
– If a patient has an active infection on the part of the body where the TAP block would be injected, the procedure shouldn’t be performed.
– Certain groups of patients, such as those on blood-thinning medication (anticoagulants), pregnant women, and those with hard-to-identify belly landmarks, should be approached with care when considering a TAP block.
– Local anesthetics shouldn’t be used in patients known to be allergic to such medications.
Equipment used for Transversus Abdominis Plane Block
When your doctor has to perform an ultrasound-guided TAP block, a type of nerve block to manage pain, they will use a variety of tools and medications. Here’s what they may use:
- A needle (27 to 30 gauge, 1.5 inch in size). The gauge refers to the diameter of the needle.
- A 20 milliliter syringe, which is a device used for injecting or withdrawing fluids.
- A smaller, 5 milliliter syringe.
- Sterile (germ-free) gloves and towels to prevent infection.
- An anesthetic agent, either ropivacaine or bupivacaine without epinephrine. These are medicines used to prevent pain in a part of your body.
- Liposomal bupivacaine, another type of anesthetic.
- Local anesthetics such as 1% lidocaine, also without epinephrine, which numbs the skin.
- Skin cleansing agents like 2% chlorhexidine which helps to clean the skin before the procedure.
- Health monitoring equipment: a pulse oximeter (a device that measures how much oxygen is in your blood), an EKG monitor (which checks your heart’s electrical activity), and a blood pressure monitor.
- Ultrasound machine and a sterile cover for the ultrasound transducer (probe) as well as ultrasound gel, which helps transmit the sound waves from the transducer into your body.
- A ‘block needle’, preferably 20 to 22-gauge in size and 5 to 15 centimeters long, which is used to introduce the anesthetic agent near the targeted nerves.
Who is needed to perform Transversus Abdominis Plane Block?
Medical doctors with the right training and skills, like anesthesiologists, can do a special procedure called TAP blocks. This procedure usually needs another healthcare provider or nurse to help out. Before they start, they take a ‘timeout’; this is when they double-check everything to ensure the procedure goes well. This second person also aids in giving a local anesthetic, which is a medication that numbs a specific area of your body and helps you not to feel any pain during the procedure.
Preparing for Transversus Abdominis Plane Block
Before performing a medical procedure, the doctor needs to inform the patient of the risks and benefits, and talk about any other options available. This is an important step known as obtaining ‘informed consent’, which means that the patient fully understands what is going to happen and agrees to the process. After this, it’s critical to closely watch the patient’s health during the procedure. This is done by continuously checking the patient’s heart rate with an EKG (a test that checks how your heart is functioning), checking their oxygen levels with a pulse oximeter (a device that is attached to a finger or earlobe), and monitoring their blood pressure every 5 minutes.
Before the procedure begins, the patient will have an IV (a tube that goes into a vein) inserted for easy access to give medications or fluids if needed. The patient will be placed flat on their back and the doctor will make sure the stomach area is uncovered. The skin on the front side of the abdomen, between the ribs and the hip, will be cleaned thoroughly to help prevent infection. For additional cleanliness, sterile towels will be placed around the surgery area to create a clean working spot for the doctor. Before starting the procedure, a ‘procedural time-out’ is taken. This is a pause before the procedure begins to double-check everything and make sure nothing has been missed.
How is Transversus Abdominis Plane Block performed
Using landmarks on the body to carry out Transverse Abdominis Plane (TAP) blocks (a type of local anesthetic injection) isn’t the common choice these days. Thanks to ultrasound machines, these injections have become safer and easier to do. To do a TAP block, doctors look for a triangular area on the body known as Petit’s lumbar triangle. It can be found in the area bound by your side belly muscle (external oblique), upper hip bone (iliac crest), and a back muscle (latissimus dorsi).
Once this triangle is found, a needle is introduced. The doctor will feel two ‘pop’ sensations as the needle goes through two different layers of muscle. The first layer is the fascia deep to the external oblique muscle and the second layer is the fascia deep to the internal oblique muscle. The doctor checks to make sure the needle isn’t in a blood vessel, and then injects the anesthetic slowly, checking intermittently to make sure the needle hasn’t gone into a blood vessel. During this process, patients may feel a sensation similar to pressure.
When using ultrasound, the doctor looks at a section of your belly between the hip bone and rib cage along the side of the body. The ultrasound will show different layers from the skin and fatty tissue down to the muscles of the abdomen. The thickest of the three muscle layer is usually the internal oblique, while the transversus abdominis muscle, another layer, is often the thinnest. The doctor must be sure to avoid placing the needle in the area where the bowel is located beneath the transversus abdominis muscle. The ultrasound allows the doctor to track the needle’s path and safely inject the anesthetic into the correct spot between the muscles. As the anesthetic is injected, it pushes the transversus abdominis muscle deeper.
Usually, 15 to 20 ml of local anesthetic is used, depending on the patient’s weight and the concentration of the anesthetic. It is possible to carry out TAP blocks on both sides or just one side of your body, depending on where the surgery is located. Sometimes, during surgery, doctors can also perform a block on the abdominal wall from inside the belly.
Possible Complications of Transversus Abdominis Plane Block
Complications linked to TAP (transversus abdominis plane) blocks, a type of anesthesia used to numb your stomach area during surgery, are not very common. These blocks work by spreading anesthesia over a wide area, rather than focusing on a specific nerve, so chances of nerve damage are low. Still, some issues could occur such as injuries to the nerve caused by the needle used, blood clot, or infections close to the injection site. If the needle goes too deep, it might accidentally inject the anesthesia into the abdomen or hurt organs and blood vessels, including the liver. Certain cases have also reported a temporary problem where the femoral nerve in the thigh stopped working.
To avoid such problems, doctors often use ultrasound as a guide to placing the block. This is more accurate than older methods that relied on ‘feeling’ their way through different layers of tissue. Being careful is essential because the anesthesia is injected in an area with lots of blood vessels. That’s why it’s essential to make sure the needle doesn’t poke a blood vessel and the medication doesn’t enter the bloodstream. Although not common, an overdose of anesthesia in the bloodstream is a known risk and it can be harmful.
What Else Should I Know About Transversus Abdominis Plane Block?
‘TAP blocks’ is a type of pain management technique used for surgeries involving the abdominal wall. These blocks have become an integral part of how doctors manage pain associated with these types of surgeries. The reason they are so widely used is that they are safe to perform, relatively simple to administer, and very effective at managing pain. This makes them an excellent addition to the other pain management methods used before, during, and after surgery.