Overview of Thoracic Paravertebral Block
Lung cancer is a top killer amongst all types of cancer for both men and women, causing a quarter of all cancer-related deaths. The American Cancer Society’s data for 2020 shows this alarming statistic.
Most people with lung cancer (84%) have a type called non-small-cell lung cancer (NSCLC). The preferred treatment for NSCLC is a type of chest surgery known as a pulmonary lobectomy. However, this surgery can lead to serious complications after the procedure, such as difficulty breathing, bleeding, and pain. This pain can slow down a patient’s recovery and worsen their quality of life.
According to research analysing numerous studies, about 57% of patients experience long-term pain three and six months after chest surgery. This happens because intense short-term pain often leads to long-term chronic pain.
However, combining the surgery with a type of regional anesthesia known as thoracic paravertebral block (TPVB) can help. Studies have shown that TPVB can lessen the amount of strong painkillers someone needs after surgery and reduce inflammation, potentially improving survival rates.
The TPVB technique was first mentioned by Hugo Sellheim in 1905 for reducing abdominal pain. It was largely ignored until 1979 when Eason and Wyatt published about it. They showed its beneficial effects and since then, it’s been increasingly used to lessen postoperative pain for various chest surgeries.
TPVB involves injecting a local anesthetic into the space near the spinal nerves. This blocks pain signals in the chest area.
This explanation helps to understand why TPVB is important for surgeries involving the chest area and its role in reducing post-surgery pain.
Anatomy and Physiology of Thoracic Paravertebral Block
The paravertebral space is a triangle-shaped area found between the head and neck of a rib. The boundaries of this space include the lining of the chest cavity on the front, rib-binding ligaments on the back, the backbone on the inside, and the ribs on the upper and lower sides. This space is the location where certain important features of the spine, such as the spinal (intercostal) nerves, separate into different branches.
These nerves, which have no protective covering or “fascial sheath,” are very sensitive to local anesthetics – drugs that numb a specific area. When an anesthetic is injected into this area, it can effectively numb not only one side of the body but several different areas on the back as well thanks to the anesthetic spreading across several levels of the spine. This effect has been observed in several scientific studies, such as one by Cheema et al. (1995).
Also housed in this space is fatty tissue, nerve conduits called rami communicantes, and the sympathetic chain, which is a part of the nervous system involved in the body’s response to stress. This paravertebral space communicates with the epidural space, the space around the spine, on the inside; the intercostal space, the space between the ribs, on the outside; the cervical paravertebral space, the space at the top of the spine, above it; and the origins of the Psoas Major muscle, a key muscle in the lower spine, below it.
Interestingly, it is also possible for the injected anesthetic to spread into the epidural space or even to the opposite side of the body, as was reported by Karmakar et al. (2000) after injecting a special contrast medium through a catheter in the thoracic paravertebral space.
Why do People Need Thoracic Paravertebral Block
A thoracic paravertebral block (TPVB) is a medical procedure that numbs one side of your chest or abdomen. It’s commonly used during certain types of surgery and can help manage pain when it’s focused on one side of your torso. The TPVB can even be used on both sides during some major abdominal surgeries.
This method is often combined with other pain management procedures during surgeries on the chest, kidney, and breasts. It’s also used when doctors use small cameras to perform surgery in the chest (known as thoracoscopy), when they perform heart surgery using minimally invasive techniques, and it has been increasingly useful in breast reconstruction surgeries.
The TPVB is a great alternative for patients considered high-risk for complications during and after general anesthesia. This includes older patients with low lung capacity, those with limited lung reserves, or those with heart conditions. It’s particularly beneficial in these cases for breast surgeries.
Recent research shows the TPVB is effective for major breast surgeries. It has few complications, and only a small number of patients need to switch to general anesthesia. Plus, it greatly improves the recovery experience after surgery.
When a Person Should Avoid Thoracic Paravertebral Block
There are several reasons why a person may not be able to have a TPVB (nerve block procedure to help with pain management after surgery):
Firstly, the patient can refuse the procedure if they don’t want to have it.
Secondly, if someone is allergic or has hypersensitivity to local anesthetics (the drugs used to numb a specific area of your body), it’s not safe for them to have TPVB.
People who have blood disorders or are taking blood-thinners, known as anticoagulants, might not be able to have TPVB because it could cause serious bleeding problems. The INR value measures how long it takes for blood to clot; if it’s more than 1.4 or if an individual hasn’t stopped taking the anticoagulant for enough time as per ASRA (American Society of Regional Anesthesia) guidelines, then they might not be able to have the procedure.
If a patient has an active infection at the site where the medication would be injected, it’s too risky to perform TPVB.
Another reason could be a tumor in the area where the injection is supposed to be given.
Conditions related to lung issues like a respiratory infection, or a continually enlarging pleural (the layer covering the lungs) can also prevent a person from having a TPVB due to the risk of pneumothorax, a condition where air gets into the space around the lungs and may cause a lung to collapse.
Finally, if there’s a deformity in the rib cage, it could lead to needle puncturing into the pleural or spinal area instead of the intended area. Some authors believe that risk could be too high.
Equipment used for Thoracic Paravertebral Block
The Thoracic Paravertebral Block (TPVB) is a procedure commonly performed in many hospitals. It is carried out with the assistance of ultrasound to help avoid damage to nerves or the layer surrounding your lungs, the pleura, which could potentially result in a collapsed lung (known as pneumothorax). Here’s a simplified list of the equipment that’s used during the procedure:
- An ultrasound machine which is used to help guide the procedure. Depending on the person’s body, either a high-frequency or low-frequency curvilinear probe will be selected.
- A sterile cover and gel, which is applied to the probe to keep it clean and help the ultrasound work better.
- A needle (between 23 to 25 gauge) which is used to numb the skin and the area beneath it.
- A local anesthetic, used to numb the specific area where the procedure is being performed.
- An 80mm B-bevel nerve block needle, a special type of needle designed for these procedures.
- Sterile gauze, used for cleaning and covering the procedure area.
- A chlorhexidine gluconate solution, this is a commonly used skin disinfectant to keep the area clean and reduce the risk of infection.
- Sterile gloves for the healthcare professional carrying out the procedure.
- A marking pen that’s used to mark the precise area where the procedure will take place. This helps to guide the ultrasound and needle placement.
Who is needed to perform Thoracic Paravertebral Block?
For this type of medical procedure, it’s advised to have a medical professional who specializes in regional anesthesia, which is a type of pain control that targets a large area of the body. This specialist is needed as they can handle any issues that might come up related to this type of anesthesia, which can numb larger parts of your body.
Before the procedure starts, some patients might need to take a medication to help them feel more relaxed and less stressed. This medication is commonly referred to as an anxiolytic.
Also, a nurse who has received training in regional anesthesia should be present during the procedure. This nurse is there to support the doctor and can assist with managing sedation if needed. Sedation is a state of calm or drowsiness induced by certain medications.
Preparing for Thoracic Paravertebral Block
Before any pain-blocking procedure, it’s important to go through a thorough check-up. This includes understanding any health issues the patient has, reviewing their medical history, doing a physical examination with a focus on their breathing system, and studying any tests done before surgery.
After this check-up, the person providing the anesthesia must explain to the patient all the pros and cons of the procedure, called thoracic paravertebral block (TPVB), and all possible complications.
It is best if the procedure is performed in a clinic which specializes in pain-blocking procedures to make sure patients are monitored properly. Patient’s vital signs like pulse rate, heart activity and blood pressure need to be closely watched. The American Society of Anesthesiologists sets guidelines on how this should be done and these will be followed during your procedure.
How is Thoracic Paravertebral Block performed
The medical professionals have outlined various approaches to this procedure. The patient can choose whether they would like to sit down, lay on their side or lay on their stomach. Sitting is usually more comfortable if the patient is awake during this process.
The usual technique used in the past, as explained by Eason and Wyatt in 1979, involved the anesthesiologist using a technique called ‘loss of resistance’ to find the appropriate space near the spine to inject the local anesthetic. Once the area is properly cleaned, the needle is inserted about an inch to an inch and a half to the side of the bony part of the spine (spinous process). The needle is pushed in straight until it hits the bony part of the vertebra on the lower side. The needle is delicately moved further until there is no resistance felt to air. This means the needle has gone through a tough band of tissue known as the costotransverse ligament. After a gentle pull back on the syringe to make sure no blood comes out, the numbing medicine is injected.
But, many modern specialists in regional anesthesia (numbing a specific area) now prefer not to use this technique due to a higher rate of not achieving the desired result. One of the complications includes accidentally piercing the outer covering of the lung (parietal pleura), leading to air escaping from the lung into the chest cavity (pneumothorax). So, the procedure has been modified to include ultrasound guidance, which helps ensure the needle is put in the right spot.
In 2009, a study by Luyet et al. described using ultrasound to guide a tube placement in the space near the spine. Subsequent studies have supported the use of ultrasound technology in this process.
Once the site is cleaned, the specialist uses ultrasound to visualize the region near the spine that is going to have the procedure. The specialist uses an ultrasound probe to capture images. They will locate the spine’s bony parts between the first and eighth vertebra based on certain landmarks like base of the scapula, which corresponds to the seventh thoracic vertebra. They then move the ultrasound probe sideways and obliquely to visualize three crucial structures: the double layer of the internal intercostal membrane, the transverse process and the outer covering of the lung (parietal pleura) moving in sync with the patient’s breathing. After numbing the skin with 2% lidocaine, a needle guided by the ultrasound is placed about half an inch below the ultrasound probe. When the needle reaches the space between the internal intercostal membrane and the lung’s lining, the numbing medicine is slowly injected over a 30-second period.
Possible Complications of Thoracic Paravertebral Block
Sometimes, certain complications can occur during techniques used to numb a region of your body for surgery apart from the usual issues, like infections at the injection site, blood clots under the skin, nerve damage, or side effects due to too much of the numbing medicine. The paravertebral block is a specific type of anesthesia that can lead to rare complications. It may pose a risk of puncturing or collapsing a lung, causing blood to accumulate in the chest or injecting into the protective covering of the spinal cord.
In some cases, patients undergoing chest surgery might experience a lung hemorrhage, or bleeding in the lungs, as a result of the use of the paravertebral block.
Other complications can occur, including one that results in weakening or paralysis on one side of the diaphragm, the muscle that helps with breathing. A block of the nerves that serve the arm and hand on the same side, known as an ipsilateral brachial plexus block, has also been reported.
In rare cases, the numbing medication might accidentally spread to a collection of nerves near the neck, known as the ipsilateral stellate ganglion, leading to a condition called Horner syndrome. This can cause a drooping eyelid and decreased sweating on one side of the face.
However, thanks to advancements in ultrasound technology, these complications are becoming less common, increasing the safety of these procedures.
What Else Should I Know About Thoracic Paravertebral Block?
The thoracic paravertebral block (TPVB) is a type of anesthesia used during chest surgeries. It’s a safe technique that has few complications, largely thanks to the use of ultrasound. The TPVB helps to mitigate the body’s stress response to surgery by blocking certain nerve signals. This allows for major chest surgeries to be performed with the patient experiencing minimal pain during and after the operation.
Usually, a procedure called thoracic epidural is considered the standard choice for pain control during major chest surgeries. However, the TPVB can be just as effective in managing pain, with the added benefit of having fewer side effects. So, it’s a good substitute if, for some reason, a thoracic epidural can’t be used.
Research has shown the benefits of TPVB. For instance, a recent study looked at patients with a type of lung cancer called non-small cell lung cancer who were having a specific surgery called a lobectomy. By using the TPVB with ultrasound guidance during these surgeries, the researchers found not only an improvement in patients’ pain levels after their surgery, but also better recovery and improvements in their quality of life.
The TPVB has also been found to be effective for acute pain control in the emergency room for patients with multiple rib fractures as a result of trauma.
A study was done using the TPVB in women who were about to have a mastectomy (a surgery to remove one or both breasts). The researchers discovered that the patients who received the TPVB used significantly less morphine, a potent painkiller, in the 48 hours after surgery when compared to a control group.
There was also a comparison study that looked at the TPVB and a different anesthetic technique known as a pectoral block in people undergoing breast surgery. The authors concluded that, compared to the TPVB, pectoral blocks provided only a slight boost in pain relief after surgery.
A separate study found that the TPVB was not only safe but also effective in controlling pain and improving the satisfaction of patients who had undergone video-assisted chest surgery.
Finally, a different study that looked at patients having single-port video-assisted lung surgery found that those who had TPVB experienced significantly less postoperative pain than the control group. Therefore, the authors concluded that TPVB is a suitable and safe method for pain management in these patients.
