06.00-05 Local Anaesthesia
Before inserting sutures, a wound should be thoroughly cleansed and infiltrated with a local anaesthetic. This module will introduce the instruments, drugs and techniques you will need for local anaesthesia, together with key information on managing your patient.
In this module
06.01 What is Local Anaesthesia?
Anaesthesia means "loss of sensation" and allows a procedure to be carried out without your patient feeling any pain. Local anaesthesia is the most common technique for minor procedures and is the focus of this chapter. A local anaesthetic numbs a small part of the body where the procedure is taking place. It is used when the nerves can easily be reached by drops, sprays, ointments or injections. The patient stays conscious but free from pain.
06.02 Other Types of Anaesthesia Video 1
There are several other types of anaesthesia, although these will not be covered in detail in this course:
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. Examples of the most common regional anaesthetics are spinal and epidural anaesthetics. Again, the patient stays conscious but free from pain.
06.03 Other Types of Anaesthesia Video 2
General anaesthesia is a state of controlled unconsciousness during which your patient feels nothing. This is essential 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 and stop the brain recognising messages coming from the nerves in the body.
06.04 Other Types of Anaesthesia Video 3
Nerve blocks lie between local infiltration and regional anaesthesia and are increasingly used. The procedure is usually performed with the aid of ultrasound to enable the surgeon to view the placement of the needle.
In this example, the injection is being carried out on a patient's left brachial plexus, a bundle of nerves that leads to the arm, prior to surgery on a broken wrist.
06.05 Golden Rules
In this section we cover 7 basic rules that MUST be followed prior to and during the administration of local anaesthetic:
- good patient management
- accurate and complete record keeping
- sharps safety
- safe use of anaesthesia in end arteries
- awareness of signs of systemic toxicity
- safe use of anaesthesia around infected skin
- waiting for effect
06.05.01 Patient Management
Before the procedure, you must take a thorough medical history, checking for contraindications to local anaesthesia. This includes absolute contraindications, in other words known hypersensitivity to local anaesthetic agents, and relative contraindications such as needle phobia and extreme anxiety.
Be aware of your patient as a whole person throughout the procedure. Explain what you are going to do in terms which suit each patient’s understanding. Talk to your patient throughout, avoiding the use of trigger words such as “pain” or “hurt”.
Remain constantly aware of how your patient is reacting, so that you recognise problems early on. Emphasise that you will allow time for the anaesthetic to take effect before starting the procedure.
Patients may sometimes faint and should therefore be in a relaxed position in a chair or on a couch, so that they cannot injure themselves or you.
Warn your patient about postoperative pain when the anaesthetic wears off and how to deal with it. Provide written information about what to expect and what to do if problems arise.
06.05.02 Keeping Records
It is vital that the following information is recorded as an absolute minimum:
- drug name
- with/without adrenaline
- concentration
- amount
- who administered it
06.05.03 Sharps Safety
Always make sure you are familiar with the Sharps Safety Policy of the healthcare setting where you are working. If you are the person using the needle you are responsible for its immediate disposal in an approved sharps container. Never leave sharps to dispose of later and never expect someone else to dispose of them for you, as this increases the risk of contamination and needle stick injury.
06.05.04 End Arteries
Never use local anaesthetic containing adrenaline when anaesthetising any part of the body supplied by an end artery, for example finger, toe, nose, ear or penis.
Adrenalin in an end artery causes intense vasospasm and may completely cut off the blood flow beyond the point of injection. If the collateral circulation is inadequate the territory of the affected artery may become ischaemic, with disastrous consequences.
06.05.05 Toxicity
Major problems caused by local anaesthesia are rare, but you must be aware of the signs of systemic toxicity and act quickly if they occur. Make sure you are up to date with your national guidelines for resuscitation and treatment of anaphylaxis.
You will find information on safe dosages of anaesthetic in the chapter on Anaesthetic agents.
Useful links:
Australian Resuscitation Council
06.05.06 Infection
Never inject local anaesthetic through infected skin. You should infiltrate around the infected area. Alternatively, you could use a nerve block rather than local infiltration.
06.05.07 Wait for Effect
Always wait long enough for the anaesthetic to take effect before starting a procedure, especially if you have given a ring block. Use a clock.
Test before starting the procedure. Pinch the tissues with your forceps, or gently touch the skin edges with a needle. If the patient feels sharp pain, more anaesthetic is required. Pressure sensation is not dulled by local anaesthetics. With adequate anesthesia, the patient may still feel a sensation of pressure when you pinch the tissues with the forceps, but it should not hurt.