Local anaesthetic nerve blocks for pain relief following surgery

Introduction

Traditional methods of relieving pain with morphine after an operation do not always work well. They can also cause unwanted side effects such as sleepiness, itchiness, nausea and vomiting.

Over the years, other ways of preventing pain using local anaesthetic drugs, have been developed. These work by numbing or blocking specific nerve fibres which prevents the transmission of a pain signal. As well as helping with the pain, this method makes it easier for you to do your physiotherapy and allows for a quicker recovery from your operation.

A nerve block may be administered as a ‘one off’ injection or may continue for a few days through a fine plastic tube (catheter) as an infusion. The type of block will be discussed with you before your operation, either by the anaesthetist or surgeon.

What the anaesthetist may do for local anaesthetic blocks for limb surgery:

• Before your operation the anaesthetist will explain the procedure to you.
• In the anaesthetic room your anaesthetist will ask you to keep very still while they locate the nerves in your arm or leg and inject the local anaesthetic. They may use an ultrasound machine to help locate the nerve/s.
• This can be done either by a single injection or by placing a catheter and infusing the medicine slowly, but continuously, down it using a special pump.

What will I feel?

• To make the whole procedure more pleasant you may be given some drugs through a needle in your arm to make you sleepy/relaxed.
• As the local anaesthetic is injected, you may notice a warm tingling feeling as it begins to take effect.
• Shortly afterwards, you may notice numbness and heaviness to the affected area.
• Your operation will only go ahead when you and your anaesthetist are sure that the area is numb.

What the surgeon may do for continuous infusions of local anaesthetic following major abdominal surgery or limb amputation:

Before your operation the surgeon will explain how they will place a catheter(s) under direct vision through which the infusion(s) of local anaesthetic will be administered post-operatively.

What other pain relief will I be offered?

As well as the local anaesthetic nerve block, you may also be given other oral or intravenous pain relieving medications. These may range from paracetamol or non-steroidal anti-inflammatory drugs (NSAIDS), to morphine or other opioid drugs. The choice and type of drug will be explained to you.

How long will the local anaesthetic last?

The local anaesthetic which has been injected as a single shot bolus should keep you comfortable for 8-14 hours following administration. Alternatively, it will last for the length of time that the infusion is running.

What if it does not work?

Your anaesthetist or surgeon will make a plan for alternative pain relief should the local anaesthetic block fail. The ward staff will monitor you carefully following your operation and the Inpatient Pain Service (IPS) will also review you to make sure your pain relief is adequate.

What about side-effects?

Please tell your anaesthetist or nurse if you begin to experience any of the following things:

• Tingling around your mouth and / or a metallic taste
• Ringing in your ears
• Feeling drunk
• Dizziness
• Blurred vision
• Muscle twitches
• Difficulty in breathing

What happens after the local anaesthetic has worn off or the infusion stopped?

Oral pain relieving medications will be prescribed and offered to you. You will also be allowed additional doses of pain relieving medications.

What can I do to help?

Engage in gentle movement whilst the block is working and if this form of analgesia is for a limb be mindful of altered sensation and potential to knock the affected area.

Relaxation can help reduce anxiety and ease any tension in your muscles. If you have any worries, please let the doctors and nurses know, as they may be able to help.