Epidural

 

This form of pain control is appropriate for operations involving the  legs such as total joint replacement of the hip or knee.

 

 

What is an epidural?

An epidural is a type of pain-killing injection given by an anaesthetist. Anaesthetic is injected through the middle of the lower back into the space around the spinal cord, so that the nerves 
that carry pain sensations are blocked below the level of the injection.

 

What are the reasons for having and epidural?

 

Epidurals are often given for pain relief during procedures to the lower limbs, and in our practice, this usually refers to knee and hip replacements. Epidurals have advantages over general anaesthetics in that the patient is conscious and recovers more quickly after an operation, there is less nausea and vomiting and post-operative pain.

 

 

 

 

 

 

What happens during an epidural?

 

You are asked either to lie on your left side, with your knees drawn up to your tummy and your chin tucked in, or to sit up and lean forward. Both positions straighten and stretch the spine and the spinal cord. The anaesthetist will carefully select a point to inject by feeling for specific bones in the spine and hips. He or she may mark this site with a pen before cleaning the skin. A small 
amount of local anaesthetic is injected into the skin around the chosen point.
 

After a minute or so, when the skin is numb, the anaesthetist will insert the larger epidural needle through the skin and towards the spine. When the needle reaches the space around the spinal cord, a fine plastic tube is inserted through the bore of the needle. The needle is then removed, leaving the plastic tube in place running from the area around the spinal cord through the skin 
to the outside. The tube is stuck to the back with dressings and sticking plaster. The anaesthetist can then inject anaesthetic drugs down this tube. 
 

Whilst the anaesthetist is preparing the site for the epidural injection and especially whilst the epidural needle is being inserted, it is very important that you stay still, as the slightest movement may mean that the needle goes too far or into the wrong place.
 
The epidural can be topped up with more anaesthetic via the fine plastic tube, which is left in place until the need for pain relief has passed. At this point, the tube is simply pulled out and the area covered with a plaster. 

 

 

What happens before the epidural?

 

If you have any neurological problems, problems with blood clotting, or have had previous back problems, then the anaesthetist may consider an epidural unsuitable. 

Usually, fluid is run into your veins via a drip on the back of the hand before or during an epidural. If the epidural is to be used during an operation then you should starve for six to eight hours beforehand. You will be advised that you may still feel movement, warmth or cold during the operation although pain should be blocked, and reassured that although conscious, you will be unable to see the operation being performed. You may want to use the toilet before the operation because you will be in bed for several hours afterwards.  What should I expect expect in hospital? The injection is given by an anaesthetist, who will explain what will happen and what you should feel as the epidural is carried out, emphasising the need for you to stay very still.

 

What are the possible common complications of an epidural?

 

An epidural is now a routine procedure. However, there can be side-effects, and the more common ones are as follows: 
 

A drop in blood pressure. After the epidural drug is given, the nurse checks your blood pressure frequently. If your blood pressure falls, then it may be necessary to give drugs and more fluids through the drip Headache. If the epidural needle nicks the covering of the spinal cord, there may be a small leak of fluid from around the cord, which causes a headache when you sit or stand up. This can last for up to a week Bleeding. There are many blood vessels around the spinal cord, and occasionally, one will be pricked as the epidural needle goes in. This requires careful observation Imbalance in pain relief. Sometimes after the epidural anaesthetic is given, the drug does not spread equally around the spinal cord, meaning that one half of the body is better anaesthetised than the other. A top-up dose of anaesthetic can sometimes correct this Loss of strength in the legs. Sometimes, the anaesthetic may block the nerves sending signals to the leg muscles as well as the pain nerves. This means that you may not be able to move your legs. The sensation wears off with the anaesthetic 

• Inability to pass urine. If this occurs, a urinary catheter can be inserted into the bladder until the problem wears off Infection. 

• Infection. This is now uncommon because of the precautions taken when inserting the epidural However, if there is an infection, antibiotics and drainage of the infected area may be necessary.

• Nausea and vomiting. Although this can occur, it is much less common than with general anaesthetic.

• Backache. This may be because of the relaxation of the back muscles after the epidural anaesthetic has been inserted 
  There is an increased chance of an assisted delivery (with forceps or ventouse) if an epidural is given to a woman in labour.

What happens after an epidural?

 

An epidural is a safe and straightforward procedure and side effects are rare. As stated earlier, the effects of the epidural will wear off in 1-2 hours, and you will not experience the drowsiness that usually follows a general anaesthetic.
 

Epidural catheters are typically used for the first several days after surgery, when pain would otherwise be at its worst, and then gradually weaned down and discontinued, normally followed by milder pain medications in the form of pills.
 

Epidurals normally provide good pain control without any appreciable sedation or alteration of consciousness, and most often the amount of local anaesthetic drug required is not enough to affect the nerves that control the muscles. Patients are therefore able to walk at an early stage, and can easily cough and deep breathe, helping to avoid the development of pneumonia.

---

For more information:

Australian Society of Anaesthetists

Epidural Anaesthesia

 

 

 

back to Anaesthesia main page