Epidural and spinal anesthesia are used during many surgical procedures. These forms of “regional anesthesia” or “regional nerve block” temporarily numb the nerves to parts of the body without affecting the brain. The techniques are effective, and for some surgical procedures, provide advantage over general anaesthetic.
Epidural and special anesthesia can be:
- Used alone (the patient is awake)
- Combined with sedative medications (given into a vein in the hand or arm) to help the patient relax or sleep lightly during surgery
- Combined with a general anaesthetic
Epidural and spinal anesthesia may reduce the stress of surgery and can help with pain relief after surgery. Both epidural and spinal anesthesia involve injections of local anaesthetic (sometimes mixed with morphine-like ‘’opioid’’ painkiller) near the spinal cord. Epidural or spinal anesthesia, or combination of both, is commonly used for many procedures including:
- Caesarean section
- Hip replacement, knee replacement, or other surgery to the leg
- Hernia repair
- Prostate removal, bladder operations and vaginal repair
- Abdominal aorta surgery
- Bowel operations
- Cancer surgery
- Chest (thoracic) surgery
Occasionally, the anesthetist may begin with a spinal and then combine it with an epidural for longer-term anesthesia and pain relief after surgery. Epidural anesthesia may be used with general anesthesia so that the pain relief can be provided after surgery. A pump can also be attached to the catheter to deliver small amounts of drugs continuously or in stages. Epidurals are often used in major surgery such as chest, bowel, hip or knee surgery. They can also be used in the diagnosis and treatment of some painful conditions such as chronic back pain. Epidural anesthesia is regarded as the most effective form of pain relief in childbirth (see ‘’Epidural Anesthesia and Pain Relief during Labour’’, an ASA patient education pamphlet available from your anesthetist). Uncommonly, the anesthetist may need to convert to a general anaesthetic. This may happen if the spinal or epidural does not provide adequate pain relief, or if other complications arise during surgery.
Benefits of Epidural and Spinal Anesthesia
Advantages of using epidural or spinal anesthesia may include the following:
- Epidural and spinal anesthesia rarely cause drowsiness
- Less risk of a blood clot forming in a leg vein
- Less risk of postoperative chest infection
- Both methods can provide pain relief immediately after surgery, and an epidural last for an extended time
- Nausea and vomiting (often associated with general anaesthetic) are lessened and prevented
- Less stress on the heart and lungs
- Patients are able to communicate with the surgeon and anesthetist during the operation (provided general anesthetic has not been given)
Before the Anaesthetic
Your anesthetist will discuss your options for anesthesia and whether:
- You want to remain fully awake
- You would like to be sedated during the operation, or
- Combination with a general anaesthetic may be appropriate.
To help prevent possible complications after your anaesthetic, disclose all health problems you may have had. Your anesthetist needs to know about:
- All medications that you may be taking, such as insulin, blood thinners (Warfarin), aspirin, herbal or other products including recreational drugs
- Any anaesthetic you may have had
- Any reaction to ant anaesthetic or other medicine by you or a blood relative
- Your smoking history
- Any bleeding disorder or easy bruising
- Previous problems with blood clots
- Recent illness including infections
- Long-term illnesses, lung or heart conditions
- Back or leg pain
- Difficulty with bowel movements or passing urine
- Previous surgery or abnormality of your back
During the surgery
As the injection takes effect, some patients feel sensations or warmth and tingling. Once the anaesthetic is working fully, numbness is felt but no pain, and usually the legs are unable to move. The operation begins only when the anesthetist is certain that the anaesthetic is working properly. Usually a screen in placed across the body so you do not see the surgery if you remain awake.
Recovery after surgery
You are moved into a recovery area where a nurse monitors the return of feeling and movement and your ability to pass urine. You may experience some tingling in the skin as feeling returns. This may take up to four hours. Your anesthetist may check on you. You will be moved to the ward when your doctor is satisfied with you progress.
Possible Complications of Epidural and Spinal Anesthesia
Epidural and spinal anesthesia are effective but do have risks. Serious complications after epidural and spinal anesthesia are uncommon. While you anesthetist is highly trained and makes every attempt to minimize risks, complications that could have permanent effects may occur in rare cases. When informing a patient about any type of anesthesia or treatment, it is not usual for a doctor to discuss in great detail all the possible side effects. However, is it important you have enough information to weigh up the benefits and risks of having the anesthesia. Most patients will not have complications, but if you have concerns about possible side effects, discuss them with your anesthetist. The following list of possible complications is intended to inform you not alarm you. There may be others that are not listed.
- Blood pressure may fall. After the epidural or spinal block is given, the anesthetist checks blood pressure regularly. A fall in blood pressure is easily treated with drugs or fluids
- After a spinal anaesthetic, spinal fluid may leak into the epidural space. This may cause a headache, and you may need to rest for several days. However, the very thin needles used today make this complication very uncommon. (About one patient in 100)
- Headache may occur after epidural anaesthetic if the needle accidently advanced into the spinal fluid
- You may not be aware of your bladder being full while the epidural or spinal anaesthetic is working. A catheter may need to be inserted temporarily into the bladder
- Shivering, nausea and vomiting
- Irregular or ineffective pain relief. If the local anaesthetic does not spread evenly (especially with the epidural), one side of the body may have better anesthesia an extra dose will usually correct this, or the block may have to be repeated.
- Local tenderness, bruising and backache around the injection site. This backache os common and usually resolves quickly, but may last for seven to 10 days.
- Intense itching
- An allergy to the local anaesthetic.
Serious complications are rare. They include the following:
- The region surrounding the spinal cord can become infected and require treatment with antibiotics. Surgery may be needed
- The local anaesthetic may be injected accidently into a blood vessel, causing dizziness, a metallic taste in the mouth, and in extreme cases, convulsions and heart-rhythm irregularities
- Epidural haematoma, a collection of blood in the epidural space that may require further treatment. Rarely, spinal surgery may be needed
- Temporary nerve damage may occur. Most cases heal within six months, but some nerve damage may rarely persist.
- Total spinal anesthesia. This occurs when a spinal anaesthetic suddenly spreads too high, or the epidural anaesthetic os accidently injected into the spinal fluid. This results in a marked drop in blood pressure, difficulty breathing and possibly a loss of consciousness. The anesthetist converts to general anesthesia in this situation.
- The overall risk of permanent injury is very low, about one case in 10,000 to 20,000.
- Permanent paralysis (paraplegia) or death is possible, but such cases are so rare is modern practice that the exact risks are not precisely known.