About Anaesthesia

Table of Contents

Introduction

Most Australians will require an anaesthetic at some stage during their life. Some will need it for simple procedures, others will need it for major complex surgery or in an emergency. Some may need anaesthesia many times during their life.

The modern specialty of anaesthesia has undergone enormous change since its beginnings. More than 3 million people undergo some form of anaesthesia every year in Australia (AIHW), and Australia is one of the safest places in the world to have an anaesthetic due to constant improvements in anaesthetist’s skill and knowledge.

The word “anaesthesia” means “loss of sensation”. It can involve making a small part of the body numb (local anaesthesia), making a whole section of the body numb (regional anaesthesia), or using powerful drugs that cause unconsciousness (general anaesthesia).

General Anaesthesia

General anaesthesia is not the same as sleep, even though anaesthetists sometimes use the word “sleep” when talking to patients.

General anaesthesia uses powerful drugs given through a vein, or sometimes as a gas, that work by blocking the signals that pass along nerves in your brain, causing a controlled state of unconsciousness where a patient is unaware and feels no pain.

These drugs also affect your entire body, including the function of the heart, lungs and circulation. Early general anaesthetics were administered by dripping liquid anaesthetics onto a sponge held over a patient’s face.

The effects were unpredictable and unsafe, and the only form of monitoring was by watching the patient’s chest move with breathing and by feeling the patient’s pulse. Modern general anaesthetics now use multiple complex drugs tailored to individual patient’s needs, and complex monitoring systems.

Like all medications, the drugs used in anaesthesia can have multiple side-effects that can affect different people in different ways.

Although anaesthetists have a detailed understanding of the biochemistry and physiology of anaesthetic agents, there is still much that we don’t yet fully understand, and large amounts of new information and research are being published all the time.

Regional Anaesthesia

As the name suggests, regional anaesthesia blocks sensation in one region of the body. Medications are given just to that one part of the body.

Regional anaesthesia can be used as the sole type of anaesthesia for surgery, or in addition to general anaesthesia to provide pain relief after the surgery. Normal sensation and the ability to move that body part returns to normal when the medication wears off.

Some well-known examples of regional anaesthesia are spinal anaesthesia, used to completely numb the lower half of the body for caesarean section, and epidural anaesthesia, used to give prolonged pain relief during labour. Both of these work by delivering local anaesthetic to the spinal cord or spinal cord nerve roots.

Nerve blocks are a form of regional anaesthesia where local anaesthetic is delivered to the major nerves that supply the part of the body needing anaesthesia, such as an arm or a leg. The entire limb (or other body segment) remains numb for several hours.

Local Anaesthesia

Local anaesthetics are given to one small location of the body, usually by injections but for some specific parts of the body local anaesthetic sprays, drops, creams or patches can be used.

Often this is used so that surgery can be done with a patient completely awake, such as for a tooth extraction. Local anaesthesia is also given during all kinds of surgeries in combination with other kinds of anaesthesia, to provide pain relief after waking up.

As the medication wears off, normal sensation returns.