Anaesthesia

Introduction

You may well have had a local anaesthetic injection during a visit to the dentist. If so, you'll know that local anaesthesia stops you feeling pain, but allows you to remain awake throughout a medical procedure.

Anaesthesia means 'loss of sensation'. A local anaesthetic can block pain signals sent from your nerves to your brain. It is used to numb an isolated part of the body.

What is a local anaesthetic? 

A local anaesthetic uses drugs to 'freeze' an area of your body, so you can remain conscious, but not feel any pain during a procedure. You will feel pressure and movement (tugging when a tooth is removed). The effect of the local anaesthetic normally lasts for a few hours.

What is local anaesthetic used for? 

An increasing number of operations and procedures are being offered under local anaesthetic. These procedures include minor operations, such as the stitching of wounds or removal of moles to more complicated procedures (eye surgery including corneal transplant or cataract surgery).

Local anaesthetics may also be used for a number of tests that may be uncomfortable to endure without pain relief, such as endoscopy or cystoscopy

What is regional anaesthesia? 

Regional anaesthetics also affect your muscles, so limbs can feel heavy and clumsy. Any movements that involve weight-bearing - such as walking or standing - may be restricted.

The most common regional anaesthetics (or regional 'blocks') are:

• Spinal anaesthesia:an injection of anaesthetic drugs into the fluid that lies between two vertebrae (or discs) in the lower back. It removes all feeling from the waist down. Spinal anaesthesia takes a couple of minutes to work and lasts for around two hours
• Epidural anaesthesia:  this is similar to a spinal anaesthetic, but uses a cannula (a narrow plastic tube which is passed into a small space just around the spinal cord (epidural space) and taped into place to stop it slipping) so that the anaesthetic can be 'topped up' as required. Epidurals are often used during surgery and childbirth and also as pain relief after an operation
  Other regional anaesthetics include:
• Caudal anaesthesia:similar to an epidural - but the needle is placed at the bottom of the spine

What is regional anaesthesia used for?  

Spinal and epidural anaesthetics are often used for operations on the lower body, such as Caesarian sections, hip replacements or bladder operations.

Spinal anaesthetics are often used when a general anaesthetic is considered too risky (especially in older people).

Epidurals are a common pain relief option offered to women during childbirth.

What is sedation?  

Sedation is when small amounts of sedative drugs are used to make you physically and mentally relaxed.

Sedation may be used during a procedure which could cause discomfort, or about which you feel anxious. It can be administered lightly, so you can still talk and follow instructions, or a larger dose may make you drowsy so you fall asleep during the procedure. People who have had sedation may not have a clear memory of what has happened.

Sedation is often given alongside regional or local anaesthesia.  Sedative drugs can be inhaled (gas and air), swallowed, or injected. Although most of the effects wear off within six hours, it can be 24 hours before you're completely back to normal.

Who gives me a local anaesthetic? 

Usually a local anaesthetic will be given by the doctor or surgeon doing the operation.

Regional anaesthetics are given by anaesthetists. These are doctors who have specialist training in anaesthesia, as well as pain management and emergency care.  If you have to have a regional anaesthetic, your anaesthetist will discuss it with you and inform you of the risks.

The anaesthetist will also make sure you are fully numb during the procedure and that when you come round afterwards you will be comfortable and pain free.

How are local and regional anaesthetics given? 

• Local anaesthetic drugs can be given by injection, by spraying liquid on to the skin; by using of drops, or by rubbing an anaesthetic cream into the skin. They work quickly, often within a few minutes, although the cream may need to be applied a couple of hours prior to the procedure. If the anaesthetic is injected, it can sting for a few seconds, but the skin will then lose feeling.  No special preparations are needed prior to a local anaesthetic. You can eat and drink normally. Depending on what was done, you may be able to drive home afterwards
• Prior to a regional anaesthetic, you will be given special instructions regarding food and drink.  You may be asked not to eat or drink for a few hours before the anaesthetic is given. A local anaesthetic will be given in the spinal area to reduce any discomfort of inserting the needle used for a regional anaesthetic.  When this has numbed the area, the anaesthetist will ask you to remain still so the needle can be directed to the right place.  When the needle is inserted, you will be asked if you can feel anything. 

The procedure won't begin until the anaesthetist is certain you are fully numb in the area

What happens afterwards? 

It will take a few hours for the local anaesthetic to wear off. When it does so, you will have full feeling back, including any pain. You will be able to go home soon after the procedure.

It may take a number of hours to regain all feeling after a regional anaesthetic.  Because it can be difficult to sense when your bladder is full, as a precaution, a catheter may have been inserted while you are under the anaesthetic so that your bladder will drain.

You should be able to go home when you have fully recovered and you have eaten and drunk and shown that you can pass urine. You will probably be advised not to drive for a short time afterwards.

Are there any side effects or complications? 

Risks and complications of local anaesthesia are rare. In a very few cases, you may experience redness of the skin. Rarely, some people have an allergic reaction to the anaesthetic.

Risks and complications of regional anaesthesia include:

• Nausea and vomiting
• Feeling faint
• Dizziness and blurred vision
• Shivering
• Headache
• Bruising and soreness
• Confusion

More unusual side effects include:

• A small risk of infection
• Damage to the nerves
• Possible paralysis (rare)

Risks and complications of sedation include:

• Headache
• Nausea
• Sickness
• Amnesia - or more rarely, bad memories of the procedure.

Click through information and support links:

The Royal College of Anaesthetists