About your anaesthetic

An introduction to anaesthesia

This section aims to offer you information regarding the types of anaesthesia available for shoulder surgery. There are wide differences in how much information people want. Only you can know how much you want to know. We have tried to offer you some useful information here. Your anaesthetist will discuss the anaesthetic methods that are appropriate for you and will find out what you would like. Sometimes you can make choices if you want to – anaesthetists try to offer individual care. You and your anaesthetist can work together to make your experience as pleasant and free from pain as possible.

What is "anaesthesia"?

The word "anaesthesia" means "loss of sensation". If you have ever had a dental injection in your mouth or pain-killing drops put in your eyes, you already know important things about anaesthesia.

• It stops you feeling pain and other sensations.
  
• It can be given in various ways.
  
• Not all anaesthesia makes you unconscious.
  
• It can be directed to different parts of the body.
  

Drugs that cause anaesthesia work by blocking the signals that pass along your nerves to your brain. When the drugs wear off, you start to feel normal sensations again, including pain.

Some types of anaesthesia

Local anaesthesia
A local anaesthetic numbs a small part of your body. It is used when the nerves can easily be reached by drops, sprays, ointments or injections. You stay conscious but free from pain.

Regional anaesthesia
Regional anaesthesia can be used for operations on larger or deeper parts of the body. Local anaesthetic drugs are injected near to the bundles of nerves which carry signals from that area of the body to the brain. The most common regional anaesthetic used for shoulder surgery is an interscalene block

General anaesthesia
General anaesthesia is a state of controlled unconsciousness during which you feel nothing and may be described as "anaesthetised". This is important for some operations and may be used as an alternative to regional anaesthesia for others.

Anaesthetic drugs injected into a vein, or anaesthetic gases breathed into the lungs, are carried to the brain by the blood. They stop the brain recognising messages coming from the nerves in the body.
Both local anaesthesia and regional anaesthesia may be used alone or in combination with general anaesthesia, for example, to provide good post-operative pain relief.

Anaesthesia for shoulder surgery

For shoulder surgery we generally use a combination of a General anaesthetic and a regional anaesthetic called an interscalene nerve block. This ensures among other things that the best post-operative pain relief is achieved often allowing you to go home earlier. Sometimes an interscalene block may be used alone if you would prefer to be awake during the operation or if a general anaesthetic is not suitable. Similarly a general anaesthetic may be administered alone if you do not want an interscalene block or if it is unsuitable for you.

Interscalene Block
An Interscalene block (ISB) is a nerve block in the neck used to either:

1) Provide a heavy numbness in the shoulder and arm (in the same way that a dentist can numb a tooth) so that shoulder surgery can be carried out “awake” or under mild sedation and/ or

2) to provide excellent pain relief for shoulder surgery carried out under general anaesthesia.

The benefits of an interscalene nerve block (ISB) for shoulder surgery are:

• Excellent pain control
  
• Reduced risk of nausea and vomiting.
  
• Lighter general anaesthetic with speedier recovery from the anaesthetic
  
• Earlier to leave hospital
  
• Early intake of food and drink
  
• Less chance of an overnight stay at the hospital
  

Block Technique
The Anaesthetist and you need to decide jointly whether you are suitable for an ISB.

If you have any problems with your diaphragm (muscle used in breathing) on the opposite side of surgery or any weakness or paralysis in the opposite arm to surgery, you may not be suitable for an ISB.

Some elderly patients with severe breathing problems may not be suitable for an ISB

Performing an Interscalene block is normally only associated with mild discomfort and for this reason it is the usual practice to perform the block with you under mild sedation as it both safer and easier to carry out the procedure whilst you are drowsy. It may be carried out under general anaesthesia if you are especially anxious but this is something you should discuss with your anaesthetist.

A special needle with a small electric pulse is used to locate the correct nerves. To judge the position of the injection, the anaesthetist looks for muscle twitches in the arm. This is a peculiar sensation but it is completely safe. When the anaesthetist is happy with the position of the needle, he or she injects some local anaesthetic. The arm and shoulder soon becomes heavy and numb. If you are to remain awake for the operation the anaesthetist will test the numbness of the arm before proceeding further or this is the point at which you will be given the general anaesthetic.

Leaving Hospital

Pain Control
The main nerve block technique used in day case surgery is a single injection that lasts 12-30 hours.

After leaving the hospital, it is extremely important that you take regular pain killers at the prescribed times from the moment of discharge. This is to avoid unpleasant pain at the time when the nerve block begins to wear off (which can be in the middle of the night). Pain killers are in the form of regular paracetamol and a non-steroidal anti-inflammatory drug, usually etoricoxib and dihydrocodeine or tramadol.

Management of the “Numb Arm”
You should carry the “numb” arm in an arm sling until normal sensation and motor function return. You should receive instructions about how to look after the shoulder and arm – it should be protected from heat or pressure injury and extremes of movement. You should take care not be come in contact with extremely hot or cold items because you will not be able to protect yourself from injuries of extremes of temperature.

Side effects of ISB
Most side effects are related to the local anaesthetic spreading and numbing the nerves adjacent to the ones that supply the shoulder and arm. Any or all of the following can occur, but all resolve spontaneously as the effects of the local anaesthetic wear off.

Shortness of breath – The injection in the neck can also numb half of the diaphragm (a muscle used in breathing). Some people can feel slightly short of breath, although in most this does not affect greatly the ability to breathe adequately.

Block failure – 2%. Failure of the block to take effect will happen occasionally, if you are having your operation under a general anaesthetic we will usually know when this has happened and will administer strong painkillers before you wake up, though these are not as effective as the interscalene block had it worked. Additional painkillers are available in the recovery room when you wake up.

Blurred vision (Horner's syndrome) – 20%. This is seen as a drooping eyelid and slightly blurred vision on the side of the block and it is usually not a problem. Symptoms will pass as the block wears off.

Hoarseness – 15%. Due to the nerves supplying the voice box being numbed. This improves as the local anaesthetic wears off.

Difficulty swallowing water – 15%. Due to nerves supplying the voice box and throat being numbed. This effect can usually be overcome by “conscious” swallowing and usually it is not a problem.

Complications of ISB
These are the result of the needle being inserted either in the wrong direction or too far. They are both extremely rare and easily dealt with, with little no after effects.

Seizures and serious long term nerve damage - less than 0.001% risk and reduced by carrying out the nerve block awake.

Fortunately, the serious side effects and complications are uncommon.