Medical Questions » Anaesthetics Questions » Question No. 41
| Question: | I am going to have an anaesthetic injection into my back for my operation, as I have been told I am too old to have a normal one. I am worried that I will be awake during the operation and know what is happening, and this is frightening to me. What do you suggest I do? Can you explain what will happen? |
| Answer: | There is nothing to be frightened about, as you will also be given a sedative that will make you relax, and probably sleep during the operation. Although you will not be under a full anaesthetic, you will feel nothing, and see nothing because a vertical drape will be placed across your chest to block your line of vision. The anaesthetist will ensure that you will not be upset in any way.
There are two types of anaesthetic that can be given by injections into the back, a spinal and an epidural. Both can only be used when operations below the waist are being performed.
In a spinal anaesthetic, the anaesthetist places a needle into the lower back. The needle is inserted between the vertebrae so that the tip enters the spinal canal, that contains the cerebrospinal fluid that surrounds the spinal cord. The spinal cord carries all the nerve messages to and from the brain, and runs through the centre of the 24 vertebrae that form the backbone. A small amount of anaesthetic is injected into the spinal canal, so that the nerves below the level of injection no longer work and pain from the operation cannot be felt. The patient is often tilted slightly to prevent the anaesthetic from flowing further up the spine and affecting nerves above the level required for adequate anaesthesia.
The side effects of a spinal anaesthetic include low blood pressure, a headache for several days, and a slow heart rate. Nausea and vomiting are less common complications.
An epidural anaesthetic is very similar to a spinal anaesthetic, but the injection into the back does not penetrate as deeply and does not enter the cerebrospinal fluid. The spinal cord is wrapped in three layers of fibrous material (the dura), and this anaesthetic is given into the very small space between the outer two layers. The procedure is technically more difficult, but the side effects are less severe. Epidural anaesthetics are used most commonly to relieve the pain of childbirth. |
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