Epidural Anesthesia

Overview of Epidural Anesthesia

Epidural anesthesia is a special type of pain relief where medication is injected into the area around your spinal cord – this space is known as the ‘epidural space’. It helps to numb your body in the chest, tummy, pelvic and leg areas. Doctors often use it during operations, for chronic pain relief or to lessen muscle tightness. It’s possible to adjust the type of drug used and how it’s given (whether in one go or continuously) based on a patient’s specific needs. It’s a method that has been used successfully for over 100 years.

One of the main advantages of epidural anesthesia is it can help reduce the need for opioid medicines during and after surgery. Opioids are strong painkillers, but they can have side-effects. This is particularly important when treating children because there is ongoing debate about the potential negative effects of certain anesthesia drugs on brain development. This method is also useful after surgery as a part of varied approach to pain management.

During COVID-19 pandemic, epidural anesthesia was beneficial because it offered an alternative to certain types of general anesthesia that can potentially spread the virus in the air.

However, recent studies suggest that other less invasive methods of anesthesia might be better. There are also risks and complications linked to using epidural anesthesia, so health care professionals need to be able to identify the suitable cases for its use and be aware of the possible risks and benefits. Offering the best patient care also requires understanding the latest techniques for administering epidural anesthesia and knowing how a team of health care providers can work together to achieve the best results for the patient undergoing the procedure.

Anatomy and Physiology of Epidural Anesthesia

The spinal cord is a very important part of your body that stretches down from your brain to around your lower back. Contrary to what was previously thought, even in newborns, the spinal cord typically ends around the second lumbar vertebra, which is situated in the lower back. From this point on, the nerves found in the lower back and pelvic region come together to form what’s known as the cauda equina. The spinal cord “floats” within a special protective fluid and is surrounded by the arachnoid mater, a delicate connective tissue. This protective layer extends even further down in children and newborns.

The area around the spinal cord, known as the epidural space, stretches from the base of your skull all the way down to the bottom of your spine. This space contains fat, connective tissues, blood vessels, and fluid-carrying channels known as lymphatics. This area is divided into the front (anterior) and the back (posterior) sections. These sections contain different types of nerves and blood vessels. The epidural space’s boundaries are formed by the dura mater and arachnoid mater from inside, the ligamentum flavum and the vertebral periosteum from outside, and the foramina laterally.

Understanding the anatomy of the epidural space is really important for administering epidural anesthesia, a type of medication that helps with pain relief during surgeries, childbirth, etc. By targeting specific parts within this space, doctors can help manage your pain effectively and reduce the chances of complications.

To find the epidural space, doctors use several techniques. One common approach relies on using your anatomy – like the spinous processes and interspinous spaces in your vertebrae – to guide the needle to the right spot. Another technique, called ‘loss-of-resistance’, involves feeling a change in resistance as the needle enters the epidural space.

The ‘caudal epidural block’, a specific way of administering anesthesia into the lowermost part of the epidural space, is often used in certain surgeries for both children and adults. The anatomy of this part of your body can affect how easy it is to administer this type of block. So, it’s important for doctors to understand its detailed structure. Even with thorough understanding, anatomical variations can sometimes make it difficult to correctly place the needle. In such instances, ultrasound can help guide the needle correctly.

Why do People Need Epidural Anesthesia

Epidural anesthesia, a method of pain relief, is commonly used during childbirth to relieve the pain of labour. In addition to this, it could also be used for surgeries focused on the chest, abdomen, or spine, assuming the process doesn’t require muscle relaxation. This type of anesthesia can also help to manage pain during surgery or afterwards.

Those with conditions like heart disease that increase their risk of complications after surgery, could actually benefit more from epidural anesthesia. This method could help preventing post-surgery lung issues and aid in faster recovery of intestinal function.

A detailed study was conducted comparing the use of patient-controlled pain relief, where the patient decides when to use the pain relief, after abdominal surgery. This study compared the use of epidural or intravenous methods for pain relief. The result showed that epidural method tends to give a better outcome in terms of pain relief, lower use of opioids, drugs used for pain relief, and lower complications after surgery.

Moreover, interesting studies have explored the effect of using epidural pain relief before and after surgery on cancer relapse and survival rates. These studies hint at a possible link between epidural pain relief and improved survival rates. Even so, other recent research shows that the benefits of epidural pain relief during a surgery compared to others types of anesthesia may not be that significant and could involve higher risk of complications.

From smaller studies, it looks like epidural anesthesia does better at controlling pain after a surgery compared to general medications. Therefore, at the moment besides the use in childbirth, epidural anesthesia may be best used in combination with other treatments. However, it needs more research before we can make a concrete conclusion on its overall effectiveness.

When a Person Should Avoid Epidural Anesthesia

While epidural anesthesia is generally safe for most people, there are some instances where it may not be the best choice. Some situations might mean it’s completely not allowed, while in others, it’s just not the best fit.

Absolute reasons not to have an epidural anesthesia include:

• When the patient doesn’t want to have one
• If there’s an infection at the location where the needle would go
• When a person has increased pressure inside their skull
• Following an injury to the spinal cord

There are also some situations where it might not be the best decision:

• When a person’s blood pressure is unstable
• If someone has a heart condition where the main heart chamber is blocked, known as obstructive cardiomyopathy
• If a person has bleeding disorders that haven’t been corrected or if they’re taking medications to prevent blood clotting
• When a person doesn’t have enough platelets in their blood, a condition known as thrombocytopenia
• If a patient is unable to stay in the required position for the epidural to be placed
• When a person has abnormal spinal structure

Equipment used for Epidural Anesthesia

Epidural needles are an important tool used in medical procedures. There are a number of epidural needles fashioned out there, like Tuohy, Hustead, Crawford, and Weiss needles, however it’s most common to use the Tuohy kind. Typically, these needles would have a thickness measuring around 17 or 18 Gauge (G), and about 3.5 inches long, although some patients with thicker body types may need longer needles.

The process also involves what’s called a ‘loss of resistance’ syringe. This syringe, made of either glass or plastic, detects any changes in resistance when it enters the epidural space, a small area in the spine where the epidural is administered. This helps the doctor place the needle correctly. The syringe can be filled with air or saline, but this doesn’t affect how well it works or the chances of complications.

Epidural catheters can also be used to give a continuous dosage of anaesthesia or pain relief following the epidural procedure. These catheters might be bendy or stiff, and have one or several holes that allow the anaesthetic to be absorbed. These usually come in a kit and also include a syringe-catheter connector.

The area where the epidural procedure will take place must be clean to prevent any infection. Doctors will use sterile gloves, a surgical cap and mask, sterile drapes, a specific skin cleaning solution, and a sterile dressing to cover the site after the procedure.

The type of medicine used in an epidural may vary depending on the anesthesiologist’s preference. Typically, a mix of local anesthetic, such as bupivacaine or ropivacaine, and an opioid like fentanyl or sufentanil is used. Generally, some IV fluids are given before the procedure starts to stop the patient’s blood pressure from dropping. Medicine like IV ephedrine or phenylephrine may be kept on standby to deal with this too if it happens during the procedure.

Doctors can use an ultrasound to guide where they place the epidural catheter. The ultrasound’s real-time images of the body inside help doctors position the catheter more accurately and safely. Using an ultrasound may also mean fewer needle attempts, fewer complications, and a lower risk of accidentally puncturing the dura (a layer around the spinal cord), infections, and blood clot formation. However, more research is needed to see if using an ultrasound is better than the traditional methods.

Who is needed to perform Epidural Anesthesia?

The anesthesiologist or nurse anesthetist is a medical expert who ensures you’re comfortable and pain-free during the procedure. They may use medication to make you sleepy or completely unconscious. Supporting staff, also known as assisting personnel, help the main doctors with various tasks during the surgery.

Preparing for Epidural Anesthesia

Before a doctor gives patient an epidural (a type of numbing medicine), they need to properly position the patient and prepare the area where the medicine will be given. They also need to make sure they have emergency equipment and medicines nearby. Additionally, the patient needs to have an intravenous line (a thin tube that goes into a vein) where fluids and medicines can be given. The doctor follows specific guidelines to make sure the patient is safe during the process. The patient can either sit up or lie on their side for the procedure, and it’s good for them to arch their back to let the doctor see the spaces between the spine better. Keeping everything clean and sterile is crucial to prevent any possible infection.

In all types of epidural procedures, doctors get the patient in the right position and ensure everything is kept sterile. They use anatomical markers, a special needle, and sometimes an ultrasound to guide them in where the epidural should go. Recent research shows that using ultrasound can make the procedure quicker and more successful. It can help reduce the number of times the needle needs to be passed in or out, increase the chances of it working on the first try, and lower the chances of complications or issues.

How is Epidural Anesthesia performed

Epidural anesthesia is a type of pain relief method used during some surgical procedures. The technique used by the doctor depends on the area of the spine that they need to access. For instance, if they need to access the upper part of your spine, they might use the paramedian approach due to the angle of the spinal bones in that area. However, if they are accessing a lower part of your spine, they usually use the midline approach.

Let’s break down what these procedures involve:
The midline approach involves inserting the needle directly in line with the spine. First, a local anesthetic is injected to numb the area and decrease any discomfort. Then, a needle, aided by a thin rod called the stylet is inserted into the skin and underlying tissues. As the needle advances into the epidural space of the spine, the doctor applies pressure on the needle giving some resistance until it reaches the right area. This drop in resistance verifies that the needle has reached the right point. The depth from the skin to this point is usually about 4 cm. Finally, a small amount of saline is injected to let the space open up and decrease the risk of injury to any blood vessels.

The paramedian approach is very similar, but the needle is inserted just to the side of the midline. Because of this different angle, the needle doesn’t pass through as many ligaments, but again the doctor relies on the loss of resistance to let them know when the needle has reached the right place.

Once the correct space in your spine is reached, an epidural catheter (a thin tube) is inserted through the needle. This catheter is usually inserted up to around the 20-cm mark on the outside of the catheter. After the needle is removed, the catheter is withdrawn slightly, leaving around 5 to 6 cm of it inside the spine.

Once the catheter is in place, the doctor will use a small syringe to gently pull back to see if your spinal fluid can be aspirated. If this fluid is drawn up, it suggests that the catheter is in the wrong place and needs to be readjusted. If the catheter is properly placed, then a test dose of anesthesia is administered to ensure its correct functioning.

Caudal anesthesia is a separate type of epidural anesthesia mainly used in children for certain procedures. This method involves placing a small needle into the lower part of the child’s spine at a certain angle. They advance the epidural catheter until they feel a loss of resistance. Similar to other approaches, if they notice blood or spinal fluid, the catheter will need to be repositioned. If it’s correctly placed, a test dose of anesthesia is given to make sure the catheter is correctly placed.

In all these methods, safety and precision are the key priorities to ensure effective pain management.

Possible Complications of Epidural Anesthesia

Spinal cord injuries happening due to anesthesia during surgery are quite uncommon, but they can greatly affect the patients’ quality of life, sometimes even leading to fatal outcomes. Some of the issues related to these injuries include temporary or permanent nerve-related symptoms, blood clots or infection in the area surrounding the spinal cord, direct injury to the spinal cord, and sticky inflammation of the thin membrane covering the brain and spinal cord. These complications might lead to weakness or loss of muscle function, loss of sensation, pain, abnormal touch sensations, and in severe cases, irreversible paralysis or numbness.

Individuals at higher risk for these anesthesia-induced spinal cord injuries include those with abnormalities in the spinal canal, very young or old patients, people who are overweight, people with diabetes, those with weakened immune systems or critical health conditions, and those who already have neurological diseases. Any conditions that could potentially increase the risk of complications should be identified in these patients before surgery. However, treating victims of traumatic spinal cord injuries in emergency settings can be very challenging due to the pre-existing tissue damage.

There are also other complications related to epidural anesthesia, which is a type of anesthesia where the drug is injected in the space outside the dura, the protective covering of the spinal cord. These complications may include:

• Low blood pressure
• Feeling sick and vomiting
• The narrowing of airways leading to difficulty breathing
• Headache after piercing the dura (protective covering of the brain and spinal cord)
• Temporary nerve-related symptoms
• Nerve damage leading to possible nerve disease; paralysis in rare cases
• Blood clots in the epidural space (space outside the dura)
• Accumulation of pus in the epidural space
• Meningitis (which is an infection of the protective membranes of the brain and spinal cord)
• Accidental injection in the spinal cord leading to total spinal anesthesia
• Infection in the bone

What Else Should I Know About Epidural Anesthesia?

Epidural anesthesia is one of the oldest techniques that doctors use to help patients feel numb or less pain during operations. When done properly, this technique offers many benefits. It can decrease the need for general anesthesia, which involves making you unconscious and might have certain risks. Epidurals can also reduce the need for strong painkillers known as opioids during and after the operation, which means lower chances of experiencing side effects from these drugs. This is especially important for children, as it helps to avoid the negative effects certain anesthesia drugs might have on their brain development.

Epidural anesthesia can also help manage pain after surgery. This was particularly useful during the COVID-19 pandemic when doctors tried to cut down on procedures that might spread the virus in the air.

However, medical experts agree that while epidural anesthesia offers excellent pain relief and can lead to better outcomes after surgery, it does come with some risks. Therefore, doctors need to make sure it’s the right choice for each patient and monitor them closely to prevent complications. Despite these risks, this technique is still one of the best options to avoid the need for opioids and pain management. It helps reduce patient complications, improve outcomes, shorten hospital stays, and lower the chance of chronic (long-term) pain, providing both health and economic benefits.

In conclusion, while epidural anesthesia is a valuable method for pain management, it does have some risks. Selecting the right patients, closely monitoring them, and intervening at the right time can help reduce these risks. Also, further research and improving anesthesia procedures can help enhance patient safety during these techniques.