Overview of Regional Anesthetic Blocks
Regional anesthesia is a type of pain control method where a specific area of the body is made numb. It’s done by injecting a numbing medicine around a nerve in that area. Unlike general anesthesia, regional anesthesia doesn’t make the patient unconscious; it just blocks the pain in a certain part of the body.
There are several benefits to using regional anesthesia instead of general anesthesia. It avoids any issues related to breathing that can be caused by general anesthesia. Also, the amount of medication used is less, which means fewer side effects. Patients also recover faster after surgery and experience less pain. This allows them to start physical therapy sooner.
Regional anesthesia can be used together with general anesthesia or after a procedure. It’s also commonly used for managing both sudden (acute) and long-term (chronic) pain conditions.
Anatomy and Physiology of Regional Anesthetic Blocks
Anesthesia is a way of numbing the body or a part of the body to prevent pain during medical procedures. There are different types of anesthesia that depend on the part of the body being numbed.
One type is neuraxial anesthesia, where medicines, like local anesthetics or painkillers, are injected near the nerves in the spine. This is done by injecting directly into spaces near the spinal cord. Different techniques are used for this, like epidural, spinal, and combined spinal-epidural anesthesia. In spinal anesthesia, a needle is placed between the bones in the lower back, around the area of the fourth and fifth lumbar vertebrae. The needle then goes through several ligaments in the spine until it reaches a specific space in the spinal cord, and that’s where the anesthesia is injected. For epidurals, the needle is also placed between the bones in the spine, but it could be in the neck, chest, or lower back. It also goes through the spinal ligaments but stops just before reaching the spinal cord.
Another type of anesthesia is peripheral nerve blocks. This is where anesthesia is injected near a nerve, and then it spreads inside the nerve from the point of injection. The numbing effect happens slowly and travels from the injection point towards the farthest ends. There’s also a kind of anesthesia that’s given through an IV. An IV is used to inject anesthesia directly into a vein at the farthest part of a limb like an arm or a leg. To prevent the anesthesia from spreading into the rest of the body, a tight band is applied to the limb. However, this type of anesthesia is not used as often because new techniques and technologies, like using an ultrasound to find the right place to inject, have become more common.
Why do People Need Regional Anesthetic Blocks
Regional anesthesia is a commonly used method by doctors specializing in anesthesia and pain management. This technique involves numbing a specific region of the body and is a skill that requires detailed training and a deep understanding of the body’s anatomy. Whether a doctor chooses to use this approach depends on several factors. These include the type of medical procedure, the unique characteristics of the patient, and the doctor’s personal preferences. Regional anesthesia is sometimes chosen to avoid the side effects that can be caused by general anesthetic drugs (like breathing problems), to help manage pain after surgery, and to treat certain long-term pain conditions.
There are three main types of regional anesthesia:
- Neuraxial anesthesia – this involves numbing the central part of the nervous system and comprises of spinal and epidural anesthesia.
- Peripheral nerve blocks – this method involves numbing a specific nerve or group of nerves.
- Intravenous regional anesthesia – in this technique, an anesthetic drug is injected into a vein to numb an area of the body.
When a Person Should Avoid Regional Anesthetic Blocks
There are times when a doctor can’t use local anesthesia, which is medicine that numbs a specific area of the body, for several reasons:
- If a patient doesn’t want to have it. It’s important that treatments are chosen together by doctors and patients, respecting the patient’s decisions.
- If a patient is allergic to local anesthetics, it would be harmful to administer it.
There are also reasons why a doctor might hesitate to use local anesthesia:
- If the area where the doctor plans to inject the anesthesia is infected, it may not be safe to proceed.
- If a patient’s blood doesn’t clot properly, a condition known as coagulopathy, they are at a higher risk of bleeding during procedures.
- If a patient already has problems with their nerves, the doctor may worry that the anesthesia could make these problems worse.
- If a patient can’t stay still or follow the doctor’s instructions during the procedure, it could be risky to use local anesthesia.
Equipment used for Regional Anesthetic Blocks
The medical tools used can vary depending on the specific procedure. In general, for some techniques, a special injection needle is essential. When getting a regional block, which is a type of nerve block to numb a large area of your body, you’ll be closely monitored with tools that check your oxygen levels, heart rate, and blood pressure. You might hear the term “regional cart” — this is simply a trolley that carries the essential emergency medicines that can be used if there are any complications.
For epidural procedures, which involve injecting anesthetic near your spinal canal to block pain, two important tools are the Tuohy needle and a special syringe used to find the right spot in the epidural space. Spinal needles have been improved over time to minimize side effects, like headaches. There are often ready-to-use kits available that have all the necessary equipment.
When performing a peripheral nerve block, which is a type of anesthesia or pain relief used for specific areas of your body like a hand or foot, the goal is to get the numbing medication as close to the nerve as possible. To find this nerve, doctors might use anatomic clues along with nerve locating techniques. One of these is a nerve stimulator, which is a small device that sends a controllable electric current to the tip of a needle. This forms an electric pulse that activates the nerve, and if the needle is close enough, a specific muscle reaction can be observed.
Another tool used for this purpose is an ultrasound machine – this allows doctors to see exactly where the needle is in relation to the targeted nerve and other structures in your body. Portable ultrasound machines exist, with varying levels of power depending on whether the structures to be observed are near the surface or deep within the body. Using both a nerve stimulator and an ultrasound machine together could improve the chances of a successful block, get the anesthesia to take effect faster, and reduce the amount of anesthesia needed and the risk of puncturing a blood vessel.
The drugs used are called local anesthetics and adjuvants, selected based on how fast they work, how long they last, their chance to block muscle movement, and any potential side effects. Anesthetics that work fast and don’t last too long include lidocaine and mepivacaine, while those that work for an extended period are bupivacaine and ropivacaine. Occasionally, these different anesthetics might be used together to make the anesthesia take effect faster while also lasting longer.
Preparing for Regional Anesthetic Blocks
Before the start of any surgical or medical procedure, a detailed checklist is used to ensure everything is in order. This checklist helps doctors minimize mistakes and helps keep the patient safe. It includes important details like the patient’s name, date of birth, specific surgery planned, all required signed consents, any allergies the patient has, blood clotting status, and the surgical area marked by the doctor.
Doctors use a number of monitors on the patient to ensure they stay safe during the procedure. These may include a pulse checker (pulse oximetry), a heart activity monitor (electrocardiography), and a blood pressure monitor. This is part of an accepted standard by the American Society of Anesthesiologists for safely monitoring patients under anesthesia. At the same time, a vein will have a needle (intravenous access) put in it so that medicines can be quickly given if there’s a sudden need or to help the patient relax (sedation), if required. Doctors also supplement with extra oxygen if necessary.
For any procedure using anesthesia, the appropriate equipment and medications are prepared in advance. This includes equipment to help with breathing. Also, to ensure the procedure area is as clean as possible and to reduce chances of infection, the skin is prepared in a sterile manner. Strict infection-prevention steps are followed for all steps, including the use of sterile gloves, masks, and surgical drapes.
How is Regional Anesthetic Blocks performed
Neuraxial anesthesia is a type of pain management given during surgeries. It involves injecting a drug through the back into a specific location. This can be in the spinal cord for spinal anesthesia or just outside of it for epidural anesthesia. Sometimes, these two techniques are used together to provide better pain control.
Epidural anesthesia is given by inserting a needle into the space around the spinal cord. This can be between the neck, chest, or lower backbones. You could be either sitting or lying on your side when it’s done. The needle goes into the middle or slightly to the side of two bones in your spine and passes through skin, soft tissues, and ligaments. Once the needle reaches the space around the spinal cord, the sensation could change, indicating the correct placement of the needle. At this point, a numbing drug is injected through the needle directly into this space. Most of the time, a small tube or ‘catheter’ is put into this space through the needle so that more anesthetic can be given later on if needed. A clear, sterile dressing is then placed over the needle insertion site to keep it clean and the ‘catheter’ is securely taped to your body.
Spinal anesthesia, on the other hand, involves injecting a local anesthetic into the fluid around the spinal cord. This is done by placing a needle between the lower backbones and passing it through a layer called the dura to reach the spinal fluid. The numbing drug is injected only once as opposed to the epidural where a catheter can be left in place for continuous or repeat doses. It’s most commonly used in surgeries involving the lower belly, pelvis, and legs.
Peripheral nerve blocks are specifically used for surgical procedures on the arms or legs, or for managing pain. They are performed using ultrasound equipment and nerve detectors to locate nerves or group of nerves around which a numbness-inducing drug is placed. There are several kinds of peripheral nerve blocks, depending on which part of your body needs to be numbed. Some common ones are for the arm, leg, head, neck, chest, belly, and pelvic area.
Finally, there’s a method called intravenous regional anesthesia (or Bier block), which is used for shorter procedures on the hand and forearm. It involves replacing the venous blood in your arm with anesthetic using an intravenous catheter (a small tube) that’s put into your operative hand. The procedure starts with lifting your arm and wrapping it, and then applying a tourniquet (a device used to control venous and arterial circulation for a period of time). A quick-acting local anesthetic is then slowly given through the IV and the tourniquet is left in place for at least 30 minutes to prevent the anesthetic from causing side effects. This method isn’t typically used for leg surgeries because it’d require larger amounts of anesthetic. Also, it doesn’t leave residual pain relief after surgery, meaning you’ll need more pain medicine or a surgical block later. However, it does have the advantage of not requiring special equipment.
Possible Complications of Regional Anesthetic Blocks
Getting anesthesia in the spine or around the spinal cord, known as neuraxial anesthesia, requires a deep understanding of possible side effects and risks. Each method comes with its own potential complications. The main issues that might occur with regional anesthesia (numbing a specific area of the body) include the anesthesia not fully working, damage to the nerves, and toxicity from the anesthetic medication. Major nerve damage from central nerve block procedures (numbing a group of nerves) is rare, but minor temporary injuries might happen more often (ranging from 0.01% to 0.8% cases). Anesthetic toxicity is also rare (occuring in 0.01% cases) and usually happens with nerve block procedures. Allergic reactions to the anesthesia can occur though they are not common.
A side effect that can happen after an epidural (anesthesia near the spinal cord) or spinal anesthesia is a type of headache known as postdural puncture headache, which is seen in less than 1% of cases. Another common side effect is backache, which usually resolves on its own after a few weeks but can cause discomfort. Nerve blocks in the spine can sometimes cause low blood pressure and slow heart rate, especially when administered higher up in the spine.
In rare cases, a hematoma (a solid swelling of clotted blood) near the spine can occur due to epidural or spinal anesthesia. This is rare but has the potential to cause permanent damage if not swiftly addressed. Another rare but serious complication is an epidural abscess (a pocket of pus near the spinal cord) which can occur after a neuraxial block procedure, and it is seen in 0.07% of cases.
What Else Should I Know About Regional Anesthetic Blocks?
Regional anesthesia is a form of pain control used during surgeries, which has evolved into a key part of managing pain before, during, and after operations. In essence, it numbs a specific area of your body, reducing the need for general anesthesia that puts you entirely to sleep. It’s been particularly effective in surgeries related to bones and chests, as well as during childbirth, leading to significant relief from surgical pain. The result? A marked improvement in patient recovery and overall satisfaction.
