This leaflet explains what to expect if you choose to have a peripheral nerve block placed for pain relief during and after your operation.
WHAT IS A PERIPHERAL NERVE BLOCK?
A peripheral nerve block is used for giving pain relief. It can be used during surgery to supplement a general anaesthetic, and it is continued after the operation for pain control. The peripheral nerves pass through areas which can be explored by ultra-sounds. When you have a peripheral nerve block an anaesthetist uses a needle to place a fine plastic tube (a catheter) near the nerve trunks. For pain relief after surgery, much diluted local anaesthetic is put through the catheter. This lies close to the nerves in an area depending of the site of your surgery. As a result, the sensitive nerve messages are blocked. This gives you pain relief. The local anaesthetic may cause some numbness as well as pain relief. An infusion pump is used to give pain relief drugs continuously through the catheter. The pain relief lasts as long as the pump is running. When it is stopped, full feeling will return within a few hours.
WHAT ARE THE BENEFITS OF A PERIPHERAL NERVE BLOCK?
If your nerve block is working properly, you will have better pain relief than with other methods, particularly when you move about in the bed. You should need less alternative strong pain relief medicine. This means there should be less nausea and vomiting, and you are likely to be more alert. There is also some evidence that chronic postoperative pain may be reduced.
WHAT IF I DON’T HAVE A PERIPHERAL NERVE BLOCK?
It is your choice. Your anaesthetist will tell you if he/she particularly recommends a peripheral nerve block, and what alternatives there may be. Other pain relief methods use morphine or similar drugs. These are strong pain relief medicines. These drugs have side effects that include nausea and constipation. Some people become confused when using morphine.
Morphine, or other similar drugs, can be given by mouth, by injection or using a pump that you control yourself (patient-controlled analgesia, commonly known as PCA). Alternatively, there are other ways that local anaesthetic can be given – for example, a nerve block. Every effort will be made to keep you as comfortable as possible.
CAN ANYONE HAVE A PERIPHERAL NERVE BLOCK?
No. A peripheral nerve block is not possible for some people. You will need to talk to your anaesthetist if:
- You take blood thinning drugs, such as warfarin.
- You have a blood clotting problem.
- You are allergic to local anaesthetic.
- You have an infection in the area of the block.
- You have had problems with a nerve block in the past.
HOW IS A PERIPHERAL NERVE BLOCK DONE?
Blocks can be put in:
- When you are fully awake.
- With sedation (drugs that make feel you sleepy and relaxed).
- During a general anaesthetic.
Your anaesthetist will talk to you about which might be best for you.
The steps for having an nerve blocks are:
- A cannula (drip) is placed in a vein in your arm for giving fluid.
- An echography is used to locate the nerves to be blocked.
- A needle is used to place a thin plastic catheter (tube) in the contact with nerves
- The needle is removed, leaving only the catheter in place.
HOW WILL THIS FEEL?
The local anaesthetic injection in the skin will hurt briefly. There will then be the feeling of pushing, but usually no more than discomfort as the needle and catheter is inserted. Occasionally, a sharp feeling, like an electric shock, is felt. If this happens, it will be obvious to your anaesthetist. They may ask you where you felt it. A sensation of warmth and numbness gradually develops. Overall, most people do not find these sensations to be unpleasant, just a bit strange. Feeling and movement will return to normal when the pump is stopped
COMMON SIDE EFFECTS
- Inadequate pain relief: the peripheral nerve block may not relieve all your pain. Your anaesthetist will decide if it can be improved or if you need to switch to another pain relief method.
- Difficulty or impossibility of free movement of the blocked limb. Sensation of heavy limb.
- Risk of fall: femoral nerve blocks increase the risk of fall caused by loss of muscular strength. If you are supplied with this type of block, for lower limb/knee surgery, you didn’t get up alone without the support of a nurse.
- Damage of blocked limb if injury caused by lake of sensitivity.
- Nerve damage: temporary
- Uncommonly, the needle or catheter can damage nerves. This can give numbness, loss of feeling or movement in a large or small area concerned with the block. In most people this gets better after a few days, weeks or months.
- Haematoma: the needle can do unexpected puncture of a vessel, vena or artery, which can cause a haematoma. It will resorb in few days.
RARE OR VERY RARE COMPLICATIONS
- Nerve damage: Permanent nerve damage by the needle or the catheter is rare.
- Catheter infection: an infection can occasionally develop around the peripheral nerve catheter. If this happens, it will be removed. It is rare for the infection to spread deeper than the skin. Antibiotics may be necessary or, rarely, surgery.
- Accidental epidural or intra-thecal catheter placement
The risk of complications should be balanced against the benefits and compared with alternative methods of pain relief. Your anaesthetist can give you more information and help you understand the relative risks.
QUESTIONS YOU MAY LIKE TO ASK YOUR ANAESTHETIST
- Why are you recommending a peripheral nerve block for me?
- What are the advantages and disadvantages of a peripheral nerve block for me?
- What about the alternatives?
- Who will do my block?
- Have you often used this type of pain relief?
- Do I have any special risks?
- How will I feel afterwards?
- How will I feel afterwards if I don’t have a block?