People often think that problems with the hand are small and therefore simple anaesthetic infiltrated around the area will suffice for surgery. Unfortunately this is very often not the case for three reasons:
Most procedures in the hand are therefore done either under general anaesthetic or regional anaesthesia.
- There are many structures with a confined space for instance in the finger there are blood vessels, nerves and tendons and these structures all have to be identified and avoided before a surgical procedure can be performed. Infiltration of local anaesthetic around the area can distort anatomy and potentially can lead to damage of some of these important structures.
- It is vitally important that the patient stays still while the surgery is being performed. If a patient moves around and the surgeon has a knife in his hand then vital structures can easily be damaged.
- There are a lot of important structures in the hand and it is important that a surgeon sees them. If there is a lot of blood around the surgeon's visibility is reduced so a tourniquet is very often used. A tourniquet involves a tight cuff similar to a blood pressure cuff that surrounds the arm and stops blood going down into the hand. This enables the surgeon to have bloodless field and make his job considerably easier (it must be remembered that anything that makes the surgeons life is bound to be good for the patient!).
This is where the patient is put to sleep. General anaesthetics these days are phenomenally safe and there is no real increased risk from having a general anaesthetic. The chances of anything happening under general anaesthetic are probably 1 in 100,000 patients. To be safe it is Mr Field's practice that anybody over the age of 50 that needs a general anaesthetic will have a "20,000 mile service", this involves a chest X-ray, ECG (test of the heart), and a simple blood test. This ensures that the anaesthetist is happy to use anaesthetic and is a simple screening measure also beneficial for the patient. A general anaesthetic normally involves a needle in the back of the hand and various drugs are administered into the back of the hand and the patient goes completely to sleep totally unaware of the operation as it is performed. This is a standard form of anaesthetic that has been used for years and years.
General anaesthetics have three components:
Anaesthetics have had these three components ever since they were first started in the ages of chloroform. Nowadays the components are much more effective. The problem with the pain killing aspect of anaesthetics is that sometimes they can lead to nausea and this has to be treated when the patient wakes up.
- Analgesia or pain relief
- Relaxation of the muscles
- Hypnotic i.e. the aspect that makes you forget what is going on.
This anaesthesia has totally transformed upper limb surgery. This involves local anaesthetic being infiltrated into the nerves that come out of the neck and go down the arm. There are various places where it can be infiltrated, above the clavicle (above the collar bone) which is called supra clavicular, underneath the clavicle which is called infra clavicular, into the armpit or axillary or around the upper arm bone the humerus which is called mid-humeral block.
The effect of these blocks is to totally anaesthetise or numb the hand and arm. It not only affects the sensation of pain so the patient cannot feel anything it also affects the motor activity of the upper limb so that the patient cannot move the limb, it also affects sensation and special awareness, it is quite common at the end of an operation carried out under a regional block that the patient feels that there arm is lying across their chest when in actual fact it is being elevated up in a high sling which is standard procedure after hand operations.
It is possible to vary the length of time that the anaesthetic lasts by varying the type and strength of the anaesthetic used.
These regional blocks can be used on their own so that the patient can potentially watch an operation if they want to or the patient is additionally sedated with mild hypnotics so they have no recall of the operation, or they can be used in conjunction with general anaesthetics in which case the regional anaesthesia is being used more as a method of post operative pain relief.
The big advantage of a regional block over local anaesthetic infiltration is that the regional block will anaesthetise the arm so that the area of the upper arm is also numb which means a tourniquet can be used.
During hand surgery the hand is exanquinated by means of an exanguinator and then a tourniquet is applied which stops further blood coming into the hand so it is feasible to see all the structures in the hand without being hindered the blood making the operation easier for the surgeon.
Depending on which type of anaesthetic is used these can last from 6 - 48 hours.
This is now used most commonly in the casualty department for reducing distal radius fractures. What happens is that a canular or needle is placed in the back of the hand. The hand is then elevated and squeezed so that the blood is drained out of it. A tourniquet is then put on the upper arm and through the canular that goes into a vein local anaesthetic is infiltrated into the arm. The whole arm then goes numb. It is a very good anaesthetic for casualty work but not in Mr Field's opinion for use in operations as the operating field is much wetter and unfortunately all of the blood in the hand can never be drained out this way and therefore there the blood around makes an operation much more difficult.
This is another way of anaesthetising a wrist if it is fractured so that it can be pulled straight. What happens is that 10mls of local anaesthetic is put directly into the break itself and this is used a lot in Casualty and in some parts of the country. Mr Field does not use this form of anaesthetic himself. Apparently it can be very affective and can allow a much simpler and perhaps less dangerous way than a Bier's block for manipulating fractures.
This type of anaesthesia can be used to take small skin lumps off the back of a hand or indeed off any part of the skin on the body. The problem with local anaesthetic if used to operate on deeper structures is the fact that it fills the soft tissues up with local anaesthetic and this can distort local anatomy. With the hand whenever you are operating on the hand one always has to be very aware of nerves and blood vessels and if the anatomy is distorted with local anaesthetic then it makes seeing and identifying the normal anatomy much more difficult. Therefore it is a form of anaesthesia used infrequently in hand surgery in Mr Fields' practice.
There are two exceptions to the above rule.
- Carpal tunnel release: this in 95% of cases Mr Field performs under a local anaesthetic. The anaesthetic is administered by an injection into the base of the pain. The injection is painful as the object is to get 10mls of local anaesthetic into a fairly tight space in the base of the palm. Most people equate the pain level of this injection to that of a bee sting. The pain only lasts for 30 seconds and the pain abates and the area to be operated on goes numb. The operation only last for 10 minutes and so a tourniquet is applied and the patient will feel the tourniquet. This is a tight constricting feeling and the majority of people don't have any problem with it over this short period of time.
- If the patient is very unfit due to heart or chest problems it is possible to perform a wrist block. This is where local anaesthetic is applied around the 3 nerves that supply the hand. There is one injection at the base of the palm and one injection over the back of the thumb. Mr Field uses this for short procedures such as trigger digit releases, mucous cyst excisions or seed ganglion excisions. The disadvantage of this type of anaesthesia is that the tourniquet is felt and these procedures take longer than a carpal tunnel and therefore the tourniquet can become uncomfortable. It is also vitally important that the patient stays still while the surgeon is operating.