Anaesthesia stops you feeling pain and other feelings during surgery or other procedures. This happens using medicines called anaesthetics.
Different anaesthetics may be used to make you pain-free or to relax you, make you sleepy or forgetful, or make you unconscious, during your procedure. The effects are temporary and your awareness and feeling of pain will return when the anaesthesia wears off.
How do anaesthetics work?
Anaesthetics temporarily block the nerve signals that keep you awake and aware from reaching your brain. This means procedures can be done without you feeling anything. After the anaesthetic wears off, the nerve signals reach your brain and feeling will return to the affected part of your body.
What are the types of anaesthesia?
There are three main types of anaesthesia: local, regional and general. Sedation is sometimes used with local and regional anaesthesia to help relax you or make you sleep.
1. Local anaesthesia
Local anaesthesia is used to numb a small part of your body while you are awake. It is used for minor procedures. This anaesthetic can be given as an injection or as a spray, cream or gel that is put on the area.
2. Regional anaesthesia
Regional anaesthesia is used to numb a larger part of your body. This anaesthetic is given as an injection around specific nerves. Regional anaesthesia allows you to stay awake. There are two types of regional anaesthesia:
- peripheral nerve block which is often used for procedures on your hands, arms, feet, legs, or face. They are also useful for pain relief after your operation, as the area will stay numb for a few hours.
- epidural and spinal anaesthesia is given near your spinal cord and the nerves that connect to it. It blocks pain from an entire region of your body, such as your belly, hips, or legs. It can be used for pain relief during labour and childbirth, bladder operations and hip replacement surgery.
3. General anaesthesia
General anaesthesia is used to keep you unconscious during surgery, so you will feel nothing and have no memory of what happens during your surgery. Your awareness will return when the effects of the anaesthesia wares off. General anaesthesia is given as a gas that you breathe into your lungs and as an injection through a vein. While you are under a general anaesthetic a breathing tube is put into your windpipe to help you breathe. The tube is removed as you wake up after surgery. General anaesthesia is used for many operations such as surgery on your heart, lungs, and abdomen.
What is sedation?
Sedation involves using small amounts of anaesthetic medication to make you relaxed and sleepy, but not unconscious. Many people having local or regional anaesthesia do not want to be awake for the surgery so they choose to have sedation as well. If you have sedation, you will remember little or nothing of the operation. It does not always mean you will have no memory of the operation. Only a general anaesthetic can do that.
Which type of anaesthesia is right for me?
The type of anaesthesia used will depend on the type of procedure or surgery, your health such as heart disease or diabetes and the results of tests, such as blood tests or an electrocardiogram (ECG).
Who is an anaesthetist?
Anaesthetists are doctors who have specialist training in anaesthesia. Before the procedure, your anaesthetist will discuss the best types of anaesthetic for the procedure. They'll plan your anaesthetic and pain control with you, including any preferences you have. Your anaesthetist will carefully monitor you during your operation and make sure you wake up comfortably afterwards. They may also help with pain relief after the procedure.
What are the side effects of anaesthetics?
Like all medicines, anaesthetics can cause side effects, but they don't last very long. Common side effects of general anaesthesia and some of regional anaesthesia include:
- feeling sick (nausea) or vomiting
- sore throat and dry lips
- dizziness and feeling faint
- feeling cold or shivering
- pain and bruising at the injection site
- difficulty passing urine (pee)
- aches and pains.
Are there any risks and complications?
Usually having anaesthesia is safe and major problems are rare. Your risk depends on the type of anaesthesia you get, your age, your health, and how you respond to the medicines. Some health problems, such as heart or lung disease, increase your chances of problems from anaesthesia. Being overweight, taking certain medicines, smoking and using illegal drugs can also increase your chance of problems. Your anaesthetist will talk with you about the best type for you and will review risks, benefits and other choices.
Possible complications include allergic reaction, permanent nerve damage, heart attack, stroke, organ failure, reawakening during a procedure and the risk of dying. Complications are more likely in the very young, the elderly and people with other health problems. For a fit person under 60 years of age, the chance of dying due to an anaesthetic complication is approximately 1 in 1 million. The risk for people over the age of 60 can be higher depending on other health conditions.
How can you prepare for anaesthesia?
Your doctor will let you know what to do the night before and on the day of the procedure. Here are some tips to help you prepare:
- If you smoke, stop smoking. Smoking can increase the risk of anaesthesia-related problems such as wound infections, pneumonia (lung infection) and heart attacks. It's best if you quit as soon as possible before your surgery or procedure, preferably a week or more before, but quitting even a day before helps.
- Know when to stop eating and drinking.
- If you take any medicines regularly, ask your doctor or nurse about changes to your medicine routine for the day before or the day of your procedure.
- Plan ahead for going home. Ask a friend or a family member to drive you home. Don't plan to drive yourself if you have had general anaestheisa.
The following links provide further information about anaesthesia. Be aware that websites from other countries may have information that differs from New Zealand recommendations.
- About anaesthesia New Zealand Society of Anaesthetists
- Anaesthesia NHS Choices, UK, 2015
- Stop smoking before surgery American Society of Anesthesiologists
- Anaesthesia explained Royal College of Anaesthetists
Angela is a pharmacist in the Quality Use of Medicines Team at Waitematā District Health Board. She has experience in hospital pharmacy in New Zealand and in the UK, and was previously a medical writer for Elsevier in The Netherlands. Angela is interested in promoting the safe use of medicines, particularly high-risk medicines.