Regional Anesthesia involves blocking sensations to one part of the body. By injecting local anesthetic (or numbing medicine) around a group of nerves, the anesthesia provider can block the sensation from one part of the body, such as the arm, the hand, or the foot. Most of the time the patient is given sedation before and during the procedure. A regional block can often give the patient several hours of pain relief after surgery. Regional anesthesia can be given alone, with sedation, or in combination with General Anesthesia. Your anesthesia provider may use this technique to provide anesthesia for your surgery or simply to provide pain relief after your surgery. Use of this technique will depend on the type and length of your surgery, your medical history, and your anesthesiologist and surgeon's preference. Many patients, and even some physicians, automatically assume that surgery requires general anaesthesia, and that the patient should be asleep during surgery. This is not true. Many procedures can be performed on awake patients, using local or regional anesthesia. This not only avoids the risks and unpleasantness sometimes associated with general anesthesia, but may also provide specific benefits such as reduced blood loss and better postoperative analgesia.
Nowadays most patients come to the hospital on the day of their operation, and are seen by the anesthesiologist in the pre-anesthetic assessment clinic or the day of their scheduled surgical procedure. Before meeting the anesthesiologist you could be requested to answer to a questionnaire. This questionnaire will help you organize and provide important information for your anesthesiologist. You can choose your anesthesiologist, though the multiple duties and assignments shared by the anesthetic staff may make it logistically difficult to have a given member of the staff available on the day of your operation. Please check with your surgeon about your local situation. He or she will review your medical history, examine you, and order any necessary laboratory tests, electrocardiogram (EKG) and chest X-ray. He or she will make sure that any medical conditions, which might complicate your anesthetic, are being treated as well as possible. The history should include past and current medical problems, current and recent drug therapy, unusual reactions or responses to drugs, and any problems or complications associated with previous anesthetics. A family history of adverse reactions associated with anesthesia should also be obtained. lnformation about the anesthetic that the patient considers relevant should also be documented. Occasionally, the anesthesiologist will request an opinion from another specialist, such as a cardiologist, to help in your assessment. The different types of anesthesia appropriate for you and the relative risks according to the American Society of Anesthesiologists Physical Status Classification and New York Heart Association Classification will be explained. Very rarely, your operation may be postponed or cancelled because of the risks involved. The anesthesiologist who is assigned to look after you on the day of your operation will review this information, and make the final decision with you about the details of your anesthetic. Your anesthesiologist will inform you about NPO (nothing per os): on the morning of surgery, you should have nothing to eat or drink. You may brush your teeth or rinse your mouth, but you should not eat or drink anything. If, however, you routinely take medications for your Blood Pressure or Heart in the morning, you should take your usual medications with a sip of water.
When the right amount of the right drug is injected in the right place, it will eventually work and provide good pain relief. In some cases, the correct spot is easy to identify (e.g. spinal anesthesia) while, in other cases (e.g. epidural, sciatic nerve block), it is harder to find the correct spot. Most blocks take 5-30 minutes to work. Commonly used blocks are usually 85-99% likely to work, depending on the type of block and the skill of the anesthetist. What if it does not work? Depending on the circumstances, there are a variety of options available:
There are different types of regional anesthesia:
Spinal anaesthesia involves putting local anesthetic in the patient's back to "freeze" the lower part of the body. It is usually very safe and effective. It may be associated with less blood loss, and less risk of dangerous blood clots, than general anaesthesia. Spinal anaesthesia is suitable for many procedures in the lower half of the body. In general, spinal anesthesia provides excellent pain relief during all these procedures. Patients may feel some stretching or tugging during delivery of the baby by Caesarean section, or during handling of the bowels in a hernia repair. Major orthopedic surgery may include cutting bone and hammering to insert artificial joints, and some patients dislike the noise and/or vibration this causes. You can watch some short movies about spinal anesthesia (better viewed with ADSL connection).
Epidural or peridural anesthesia uses a larger volume of anesthetic, positioned in the fat and veins further away from the spinal cord. This block takes effect more slowly, which can be an advantage in some cases. For example, an epidural is less likely to produce a severe drop in blood pressure than a true spinal block. The other major advantage is that a small catheter can be placed in the epidural space to allow the block to be continued over a period of hours or days, by using dedicated machines to infuse medications to control postoperative acute pain. While a true spinal block only lasts a few hours. You can watch some short movies about peridural anesthesia and analgesia (better viewed with ADSL connection).
Various types of plexus block
There is a wide variety of other nerve blocks, including blocks at the ankle, around the groin, in the buttocks, at the arm, at the leg. Some examples can be watched in some video clips taken from the site Peripheral Regional Anesthesia (better viewed with an ADSL connection and Quick Time plug in)
After regional anesthesia your arm or leg could be numb and weak for up to 24 hours after. Your limb to feel warmer or colder than other; this could last for 24 hours. You will need not use your arm or your legs until the numbness and weakness are gone. Be careful around hot, cold and sharp things until the numbness is gone. If these persist longer than 24 hours, please call your anesthesiologist.
In general, regional anesthesia is very safe, and usually safer than a general anaesthetic. However, the potential for side effects or complications exists with any form of anesthesia. The most common side effect of a block is a temporary weakness or paralysis of the affected area. This is often useful to the surgeon, and wears off after a while. The complications that may arise depend on the specific block. They usually occur when the local anaesthetic is injected in the wrong place. If a large volume (10-20 mls.) of local anaesthetic is injected into a vein by mistake, it may cause convulsions and even cardiac arrest. This is why physicians always inject local slowly, sucking back on the syringe to check the local is not going into a vein. Major nerve blocks are safe when performed by physicians trained in the technique. After spinal or epidural anesthesia you can have headache with a probability less than 1/100, transient neurological symptoms less than 1/5000 and permanent neurological damage less than 1/100000-150000. The risk of peridural hematoma with compression of the nervous structures is very rare.
Regional anesthesia related complications
Incidence of seriuos events related to Upper Limb Blocks
Incidence of seriuos events related to Lower Limb Blocks
From the National Medical Library a tutorial about epidural anesthesia. The tutorial is for informational purposes only and its content is general information and not medical advice. Content is not intended to be a substitute for professional medical advice. Always seek the advice of your anesthesiologist with any questions you may have regarding a medical condition or medical treatment.
Go to the NML tutorial.......
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