Anaesthesia: types, safety and what to expect on surgery day

Many people feel worried about anaesthesia before an operation. Knowing what it is, how it is given and what to expect can make the day less stressful. This article explains the main types and what happens before and after, using information from the NHS, MedlinePlus and the US National Institute of General Medical Sciences (NIGMS).

1. Introduction

Anaesthesia means using medicines, called anaesthetics, to prevent pain during surgery, some tests, tissue sampling and dental work ^{[2, 3]}. Anaesthetics can be given as a gas, through a drip in a vein, by injection near nerves, or as a lotion, spray, eye drops or skin patch ^{[2, 3]}. NIGMS says anaesthetics block pain, and that some work by changing the chemical signals between nerve cells ^[3].

Anaesthetics are given by trained staff. NIGMS and MedlinePlus say anaesthesiologists are doctors specially trained to give them ^{[2, 3]}. The NHS says general anaesthetic is given in hospital by a team led by a consultant anaesthetist ^[1].

2. Types of anaesthesia

MedlinePlus and NIGMS describe four main types ^{[2, 3]}:

• Local anaesthesia numbs a small area, such as one tooth or a patch of skin. You stay awake.
• Regional anaesthesia numbs a larger area, such as an arm, a leg or everything below the waist. It is used for childbirth, caesarean births and some hand and joint operations.
• Monitored sedation makes you relaxed or sleepy. NIGMS says you stay conscious and may be able to talk. It is used, for example, for colonoscopy and dental work. MedlinePlus describes minimal, moderate and deep levels of sedation, and with moderate sedation you are drowsy with limited memory.
• General anaesthesia affects the whole body and causes a deep, sleep-like state, with no awareness and no movement. It is used for major operations such as heart, brain or back surgery.

MedlinePlus says your overall health, your medical history and the type of procedure help decide which type you receive ^[2]. The NHS says general anaesthetic is used mainly when local, regional or sedation options are unsuitable ^[1].

3. Getting ready

For a planned operation, the NHS suggests that you can help recovery by managing long-term conditions such as diabetes, high blood pressure and anaemia, staying as active as you can, stopping smoking and treating dental problems, because the breathing tube can damage teeth ^[1]. A few weeks before surgery you may have a pre-operative assessment, with tests such as blood tests, an X-ray, an electrocardiogram (ECG, a heart tracing) or a fitness test, and you may meet the anaesthetist ^[1].

Tell staff about:

• Your medicines
• Your health conditions
• Any past allergic reactions to anaesthetic or other medicines
• Any worries, such as fear of needles

On the day, the NHS says you must stop eating and drinking for a few hours so the stomach is empty, and you will be told exact timings. Follow instructions on whether to take your usual medicines. You may be asked to use a disinfecting shower gel, and to remove jewellery, piercings and nail varnish ^[1].

4. How general anaesthetic is given

The NHS says you may first get a pre-medication to relax you, reduce stomach acid, prevent sickness or ease pain. The usual method is an injection through a small tube (cannula) in a vein in the arm, and you fall asleep within about a minute. Gas through a mask is usually used only when a vein is hard to find ^[1]. An anaesthetist stays with you throughout, checking your heart rate, blood pressure and oxygen levels, placing a breathing tube in the throat and giving fluids through a drip ^[1]. NIGMS adds that anaesthesiologists monitor your vital signs during surgery ^[3]. You may be asleep for a few minutes or several hours, depending on the procedure ^[1].

5. Waking up and going home

You wake in the operating theatre or recovery room, feeling drowsy, and may have an oxygen mask until fully awake. Staff provide medicines for pain or sickness ^[1]. The effects can last around 24 hours. The NHS says that for at least 24 hours you should have someone stay with you, and you should not drive or ride a bike, cook or use machinery, look after children alone, drink alcohol, smoke or make important decisions ^[1].

6. Side effects and risks

Common side effects include thirst, drowsiness, a hoarse voice or sore throat, shivering, nausea or vomiting, soreness at the injection site, and confusion or memory loss. These usually settle within minutes or hours ^[1]. Rare complications listed by the NHS include a serious allergic reaction, breathing difficulties, chest infection, damage to teeth, mouth or eyes, nerve damage and longer-lasting confusion, particularly in older people. Accidental awareness during the procedure is very rare ^[1].

NIGMS considers modern anaesthetics generally very safe ^[3], and MedlinePlus says risks are generally low but can include heart rhythm problems, breathing problems, allergic reactions and temporary confusion, which can last several days in some adults over 60 ^[2]. Your anaesthetist will explain the risks that apply to you.

7. When to see a doctor

Talk with your surgical team before the operation about benefits and risks ^[2]. After you go home, the NHS advises seeking urgent advice from a GP or NHS 111 (in the UK) if you are worried about side effects or they do not improve ^[1]. Contact your hospital if you have concerns about recovery ^[1].

In an emergency, call your local emergency number (112 in India, 911 in the United States).

8. Conclusion

Anaesthesia is a generally safe and closely monitored way to prevent pain, but the right type depends on you and your procedure. Preparing well, following fasting and medicine advice and telling your team about your health, medicines and allergies are the most useful things you can do.