Overview of Thoracic Segmental Spinal Anesthesia
Thoracic segmental spinal anesthesia is a type of anesthetic technique often used when a patient with serious health issues needs surgery, but general anesthesia may pose too many risks. General anesthesia is typically used for most operations, but it can sometimes lead to unwanted side effects from the drugs, delay recovery, and may not effectively control pain. Hence, medical professionals are revisiting the use of thoracic segmental spinal anesthesia for several commonly performed surgeries.
For this type of anesthesia, pain-numbing drugs are injected directly into the spine around the mid-back area and above where the spinal cord ends. Doctors were previously hesitant to perform this type of anesthesia due to the risk of potentially damaging the spinal cord, but recent evidence shows that thoracic spinal anesthesia can be safely and effectively used for a range of surgeries. This includes gallbladder removal through a laparoscopic procedure, lump removal in breast cancer patients, and surgeries for abdominal cancer.
Choosing thoracic spinal anesthesia for these common surgeries may have several benefits including improved patient safety, shorter stay in recovery after anesthesia, and better pain relief after the operation. This method of anesthetic technique, its suitable applications, its potential limitations, and the crucial role of the entire medical team in managing patients receiving thoracic segmental spinal anesthesia will be further explained in this review.
Anatomy and Physiology of Thoracic Segmental Spinal Anesthesia
The design of the middle and lower back, or thoracic and lumbar regions of the spine, may seem similar, but it’s the small distinct variations that matter when it comes to delivering anesthesia in the thoracic spine. Medical professionals have conducted MRI scans to get a deeper understanding of these regions for the sake of anesthesia applications. These studies have shown that the thoracic cord is located forward with a fluid-filled gap between the outer layer of the spinal cord (dura) and the spinal cord itself. This is the opposite in the lumbar region where the spinal cord and the protrusions from it (cauda equina) are touching the inside of the dura mater.
These findings show that the fluid-filled gap at the back of the spinal cord in the thoracic region is deeper. In one study with 50 patients, the gap between the dura mater and spinal cord in the middle of the spine was about 7.7mm at T5 and about 6mm at T10. When an injection is given in the mid-thoracic spine, care must be taken not to hit the spinal cord with the needle.
Moreover, there are important differences between the space between the spinal bones in the thoracic and lumbar regions. In the thoracic spine, these spaces are narrow and harder to reach with a needle because of overlapping of the vertebral bones. In the lumbar region, there is more space between these vertebral bones, making them easier to access. Additionally, the pointed parts of the thoracic spine bones extend downwards while those of the lumbar spine extend back. This means that when doing a procedure, the angle of the patient’s spine will influence how the needle is inserted.
Performing spinal anesthesia in the thoracic region involves the same layers of anatomy as in the lumbar region. Depending on the technique used, the needle passes through various layers including the skin, fat, several ligaments, the dura mater, the space under it, and finally into the arachnoid mater, reaching the fluid-filled gap called the subarachnoid space.
It’s also worth noting that during thoracic spinal anesthesia, fewer nerve roots are covered by the anesthetic within the subarachnoid space. This means that the anesthesia only affects the specific surgical area. This can be beneficial as it doesn’t cause the expanding of veins in the lower body parts, which could help prevent blood pressure issues during the operation.
Why do People Need Thoracic Segmental Spinal Anesthesia
Thoracic segmental spinal anesthesia is a method used to numb certain parts of your body for surgery. It is most often used for short operations and for people who might have health risks when being put completely asleep (general anesthesia) for surgery. This may include individuals who are older, have multiple health conditions, or are on a lot of medications. Also, if people can’t receive other types of spinal anesthesia, this method can be helpful. Some people might choose this option because they don’t want general anesthesia.
Surgeries that this method has been successfully used for include belly cancer surgeries, breast cancer surgeries, and laparoscopic gallbladder removals. In some cases, this method has been used with great results in people who are quite healthy, so this method might provide benefits for those individuals as well. However, future studies will need to confirm its safety in general before it can be routinely suggested for surgeries.
Before you have this procedure, it’s important that you are fully informed and give your consent. Your doctor should explain why you need thoracic segmental spinal anesthesia and what will happen during the procedure. They should also tell you about the benefits and risks, and alternatives if any. It’s important to know that you’ll be awake during the surgery. This might make you feel anxious, which is completely normal. You may sense certain things during the surgery, such as feeling some pulling or pressure. This is especially true if your operation involves making a space in your belly for laparoscopic surgery.
When a Person Should Avoid Thoracic Segmental Spinal Anesthesia
There are some conditions that make it not safe to use neuraxial anesthesia, a type of pain management used during surgeries. Here are the reasons why a doctor might decide not to use this method:
The first group of reasons are: if the patient does not want to or has not given permission to use the anesthesia, if the patient has an infection at the spot where the doctor would need to put the needle, if the patient is allergic to the drugs used in the anesthesia, or if the patient has high pressure inside their skull. This last condition could put the patient in danger because it could cause a specific type of brain herniation (brain tissue bulging into an area where it’s not supposed to be) when the fluid around the brain and spinal cord is lost through the needle.
Additionally, if the surgical procedure is expected to take longer than the time the anesthesia would work, it’s also not a good idea to use it.
There are also other conditions that might make it riskier to use neuraxial anesthesia but don’t make it completely impossible. These include having a nervous system disease (like multiple sclerosis or other diseases that cause damage to the protective coating around nerve fibers), severe infection throughout the body, severe low blood volume, and a problem with blood clotting. In the case of a blood clotting problem, a doctor might still decide to use the anesthesia depending on how severe the clotting problem is.
Heart problems like severe narrowing of the heart valves and a condition causing blockage of blood flow out of the heart, as seen with a disease called hypertrophic obstructive cardiomyopathy, might also make neuraxial anesthesia riskier to use.
Equipment used for Thoracic Segmental Spinal Anesthesia
Thoracic spinal anesthesia is a method that doctors use to numb a specific area of your body before a procedure. This involves keeping the area as clean as possible, so the doctor will wear items like a surgical hat, mask, and sterile gloves. Keeping an eye on your vital signs like your blood pressure and heart rate is equally important to make sure you are stable throughout the procedure. The doctor may even put a special tube (arterial line) in your artery to closely monitor your blood pressure, especially if there’s reason to believe that your blood pressure might not stay stable.
We also use an EKG to monitor your heart rhythm, and a pulse oximeter, a small device put on your finger, to check the oxygen level in your blood. If they plan to sedate you to start, they’ll have certain equipment ready to help you breath, supply your body with oxygen, and support your blood circulation as needed. They’ll also put in an IV line into your vein before getting started.
Doctors often use a pre-made kit for spinal anesthesia that includes an antiseptic (a substance to kill bacteria) like chlorhexidine, a sterile covering used to keep the area clean, and an anesthetic (a medication to numb the area) like 1% lidocaine for the spot where the needle will go in. The kit also includes the special spinal needle, syringes, and the solution used for spinal anesthesia. There are several kinds of anesthetics that can be used, but bupivacaine (0.5% or 0.75%) is one of the most common due to its quick start (5 to 8 minutes), lasting between 90 to 150 minutes, and lesser chances of causing temporary nerve problems. 0.5% lidocaine was used in the past but isn’t as frequently anymore because it had a higher likelihood to cause these temporary nerve problems.
Who is needed to perform Thoracic Segmental Spinal Anesthesia?
The advice is for a very skilled and knowledgeable specialist, known as an anesthesiologist, to perform a specific kind of anesthesia called thoracic segmental spinal anesthesia. This is a process to numb your body during a surgery. This professional needs to be highly proficient with this type of anesthesia, and should feel confident doing it. It’s important that other team members, like another anesthesiologist or a nurse capable in anesthesia, or other nursing staff members, are also available to lend a hand during the procedure. They are there to ensure all the proper tools and supplies are available when needed.
A significant part of their job is also to help the patient stay in the correct position on the surgery table and assure their safety during the procedure. The right posture is crucial to making the anesthesia work properly and ensuring the operation runs smoothly.
Preparing for Thoracic Segmental Spinal Anesthesia
Before starting any medical procedure, doctors carry out a thorough health check-up and ask about your medical history. The key things they want to know are whether you’ve ever had any allergies or serious reactions to anesthesia, or if there’s a history of any family members having problems with anesthesia.
During a physical exam, doctors check the middle part of your spine (the thoracic spine) for any signs of curved spine (scoliosis), previous surgeries, infections, limited motion, or any other issues that might make giving spinal anesthesia more difficult or impossible.
They will also do a basic check of your nervous system, which includes your body’s ability to sense and move. This helps them understand your overall health before the procedure.
Doctors will also review all of your lab test reports and check your vital signs (like your blood pressure and whether you have a fever) to see if there is any risk of complications during or after the procedure.
Finally, right before the procedure starts, doctors do a ‘procedural time-out’. This is when they double-check your name, the treatment you’re having, your known allergies, and make sure you have given your full consent for the procedure. This is a common safety measure in healthcare to ensure that you receive the correct treatment.
How is Thoracic Segmental Spinal Anesthesia performed
To start the procedure, you will be positioned in a sitting or side-lying position – a decision your doctor makes based on what will best suit him. Some things that could improve comfort for you include blankets and some form of sedation if required. The sitting position is typically preferred as it avoids possible twisting of the spine that can occur when you are in the side-lying position. Regardless of the position, you will need to bend your neck forward and push your lower back out in order to open spaces between the bones in your back where the needle will be inserted.
When you are in a comfortable position, your doctor will determine the correct level at which the needle should be inserted. He does this by feeling your back and using landmarks, like certain bones, as guides. Underlying ribs that touch each spine along your back can also help the doctor determine if he’s located in the lower back or upper lumbar areas. Once he’s identified the correct spot, he will “count up” and mark the skin where the needle will be inserted.
Another technique worth mentioning is using an ultrasound to find the correct vertebral level. This technique still involves “counting up”, but starting from the bottom (12th rib) and moving upwards until the correct spot is identified. Once the spot is clear, it will be cleaned with an antiseptic solution and given time to dry. Afterwards, a sterile drape is placed over the area to keep it clean during the procedure.
Your doctor will then inject a local anesthetic to numb your skin. Depending on the approach chosen, this will be done either in the middle of the area or a little bit off to the side. Things change a little here based on your anatomy. Your thoracic spine (in the chest region) has long pointed extensions called ‘spinous processes’, which angle downwards. If you are receiving anesthesia in this thoracic region, it can be difficult to insert the needle right in the middle because of these pointed processes. Instead, the needle is inserted about 2 cm off the middle line and angled towards the midline. With this approach, the needle does not come across any major ligaments and can easily reach the target area.
The insertion of the needle will proceed slowly and carefully. At a certain depth, your doctor will feel an increase in resistance followed by a ‘popping’ feeling as the needle goes through a ligament called the ligamentum flavum. The ligamentum flavum is a yellow ligament that connects adjacent vertebrae, or bones in the spine, and helps to cover the spinal cord. Once the needle is in the correct spot, the cleaning rod (stylet) is removed, and a clear liquid (CSF or cerebrospinal fluid) should start coming out from the needle.
After confirming the correct placement of the needle with a flow of clear CSF, a small amount (1 to 2 ml) of anesthesia (0.5% to 0.75% bupivacaine) is injected along with 15 to 20 micrograms of a drug called Fentanyl. Based on the specific needs of your surgery, different types of anesthetic solutions could be used.
An alternative method your doctor could use is a combined spinal-epidural (CSE) technique. In this process, an epidural space is first identified with the “loss of resistance” method, followed by the advancement of the needle through the epidural needle. This method limits how much of the needle goes beyond the tip of the epidural needle, reducing the risk of injuring the sensitive spinal cord.
After the anesthesia is injected, the needle will be removed, and you will be comfortably moved into a flat lying position on your back. Your doctor will check if the level of numbness is adequate by testing it with a pinprick. If needed, general anesthesia can be added about 5 to 10 minutes later if the numbness is not enough for your comfort.
Possible Complications of Thoracic Segmental Spinal Anesthesia
When you get a thoracic spinal blockade (a type of numbing injection in the spine), there could sometimes be complications. Luckily, severe complications are rare, but the potential risks of this procedure can include:
– Injury from the needle
– Infections like abscesses (filled with pus) or meningitis (swelling in the brain or spinal cord)
– Blood pool in the spinal canal
– Reduced blood supply to the spinal cord
– Inflammation of the thin coverings of the brain and spinal cord (Arachnoiditis)
– Numbing of the whole spine
– Sudden reduction in blood flow which can lead to fainting
– Worst case scenario, death
There are also minor complications that, while more common, should not be ignored. These can include low blood pressure, feeling sick or throwing up (usually due to low blood pressure), slow heartbeat, feeling of tingling or pricking (“pins and needles”), temporary mild hearing loss, back pain, difficulty urinating, and TNS (pain in the lower back and legs). Another minor but potentially debilitating complication is a post-dural puncture headache, which is a headache that you get after an injection in the spine and can be really severe.
What Else Should I Know About Thoracic Segmental Spinal Anesthesia?
Thoracic spinal anesthesia is a type of anesthesia that can offer vital benefits for performing certain major surgeries. This method, which puts a specific area of the body to sleep while the patient remains awake, often enables safer surgeries for high-risk patients who might struggle with standard (general) anesthesia. General anesthesia refers to when a person is put totally to sleep for a procedure.
One advantage of this technique is that it controls pain more effectively than opioid medications and reduces the amount of these drugs required during or after the surgery. This leads to fewer side effects related to those medications. Additionally, patients often recover their bowel function sooner, which can result in fewer complications and a shorter hospital stay, improving overall patient satisfaction.
Thoracic spinal anesthesia can also be beneficial for managing pain after surgery in combination with other methods. Moreover, this procedure requires a smaller dose of anesthesia, reducing the chance of instability in the patient’s blood circulation (hemodynamic instability).
Overall, administering thoracic spinal anesthesia can make surgeries possible and safer for high-risk patients, who might otherwise require a long stay in the hospital.
