What is anaesthesia
Anaesthesia refers to the practice of administering medications either by injection or by inhalation. It produces a state of unconsciousness and reduced pain which allows medical and surgical procedures to be undertaken without causing undue distress or discomfort.
Anaesthesia may be broadly divided into:
- Local anaesthesia
- Regional anaesthesia/analgesia (nerve blocks, epidural, spinal)
- General anaesthesia
These may be used individually or in combination as appropriate. For some types of surgery, several anaesthetic options are available to facilitate surgical conditions and to provide adequate pain relief. A specialist anaesthetist, in consultation with you and your surgeon, will offer the optimal type of anaesthetic for your specific needs.
Local anaesthesia involves the injection of local anaesthetic into the skin surrounding the surgical site. It may be the only type of anaesthesia or it may be combined with sedation or general anaesthesia depending on the extent and duration of surgery. It is often used for minor surgery, such as excision of skin lesions. It may not be appropriate if the surgical site is infected.
Regional anaesthesia involves the injection of local anaesthetic around major nerve bundles to reduce sensation from large areas of the body, such as the thigh, ankle, forearm, hand, shoulder or abdomen. Regional anaesthesia may be performed using nerve-locating devices such as nerve stimulators or ultrasound. These devices help to more precisely identify and locate nerves for targeted delivery of anaesthetic medications.
Regional anaesthesia may be combined with general anaesthesia or may be used on its own.
Once the local anaesthetic is injected, a patient may experience numbness and tingling around the area of the surgical site, which is an indication that the area supplied by these nerves is anaesthetised and will become numb. It may become difficult or impossible to move that part of the body, which may feel very heavy.
How long does regional anaesthesia last?
This depends on which local anaesthetic is used, the region into which it is injected and whether it is maintained by continual infusion or repeated injections. Typically anaesthesia can last from several hours to several days. Generally, the "heaviness" wears off within a few hours but the numbness and tingling may persist much longer. As the local anaesthetic effect wears off, numbness will diminish and surgical pain may return, in which case alternate methods of pain relief including injections or tablets will be prescribed.
Conscious sedation may be defined as a drug-induced depression of consciousness during which patients may respond purposefully to verbal commands or light touch. A variety of drugs and techniques are available for procedural sedation and/or analgesia.
General anaesthesia is a reversible drug-induced state of unrousable unconsciousness. General anaesthesia may be used for a variety of diagnostic or interventional procedures. If you have a general anaesthetic, an anaesthetist will look after you throughout the procedure, and use a range of monitoring devices to ensure your safety.
Your anaesthetist will assess your medical history and discuss the various options for your anaesthetic with you in detail, and will be able to address any specific questions or concerns you may have.
More information regarding types of anaesthesia can be found at the
Australian Society of Anaesthetists site
Information on fasting -
PDF document (Page 5, Appendix 1) - PS07 Guideline on pre-anaesthesia consultation and patient preparation
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