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General Anaesthesia

​​​General Anaesthesia is a state of unconsciousness, quite different from normal sleep, where a patient does not feel anything and cannot remember anything during a surgical operation or procedure. A general anaesthetic is a necessary part of many surgical operations.

Before your operation your surgeon or anaesthetist will inform you if you need a general anaesthetic or explain if there are any alternatives you can choose. 

Before your anaesthetic

Before your general anaesthetic patients you will be instructed to fast. This is an important safety measure because food or liquid present in your stomach can potentially get into your lungs during an anaesthetic. Fasting reduces this risk.

You will be given precise instructions about when to fast for food and liquids. Normally the fasting time for clear liquids is much less than for food. Please do not fast for much longer than you are instructed - missing food and drink for prolonged periods before surgery is not healthy and can also increase risk.

For clear fluids (e.g. water, tea or coffee without milk) you should fast for two hours before the scheduled time of your surgery, unless we tell you otherwise.

For food and non-clear fluids (e.g. Milo, tea or coffee with milk, orange juice with pulp) you should fast for six hours the scheduled time of your surgery, unless we tell you otherwise.

You will be given precise instructions about which of your medications to take and which to miss out. If you are unsure of what to do please contact the APAC clinic. 

Important: If you have been instructed to take medicines on the day of surgery you can take these with a small amount of plain water even if you are fasting.

Before you come to the Operating Theatre

After you have registered and been admitted to the hospital there are several things we will do before you have your operation. Some of these are patient safety checks which may be repeated several times as you progress towards the operating theatre. Other steps ensure your comfort and preparedness prior to surgery.

You will be asked to undress and wear a hospital gown. A member of staff will tell you what items you can keep on - this will depend on the procedure or operation you are having. At all times we will ensure your modesty and dignity. If you have concerns about this, please do ask a member of staff.

If you are female and of child-bearing age you may also have a urine pregnancy test. This is routine for your safety.

If you have any jewellery or piercings that are not possible to remove these will be covered with tape or a gauze to protect you. If you wear dentures these will be removed and stored safely. A hearing aid or glasses can be worn when you come to the operating theatre. 

If possible, we prefer patients to come to the operating theatre with an empty bladder so you will be invited to use the toilet right before your surgery.

Your identity, operation and consent will be checked more than once. Your surgical site will be marked. You will meet several members of the team looking after you: nurses, operating theatre staff, surgeons and anaesthetists. Each member of staff will introduce themselves to you before asking you questions, giving you information or examining you.

The hospital and operating theatre are also essential teaching and learning environments for health care professions and students under supervision are often involved in our patient care. If a student is a core part of the team caring for you they will also introduce themselves to you.

At any point you can ask questions of any member of staff. It is important to us that you understand what is happening around you and that you feel safe.

Meeting your anaesthetist
You will meet the anaesthetic team looking after you before your operation. Most commonly this is when you come to the operating suite. Even if you have been seen at the clinic beforehand the anaesthetic team will normally ask you some questions and perhaps examine you. 

At this time if there is a choice available about what sort of anaesthetic you might have, the team will discuss this with you and make a decision with you. If you have any questions or concerns about your anaesthetic or surgery the team will discuss these with you and confirm your consent.

Consent, Monitoring and IV line
Before your anaesthetic can begin, your identity and consent will be double-checked. This is one of the many ways that we keep you safe and ensures that we have the correct patient for the correct operation.

You will have an intravenous (IV) line placed, most commonly in the hand or arm. This is a necessary part of anaesthesia and involves a small injection. Sometimes veins are difficult to access and it takes more than one injection. The anaesthetist will try to do this as painlessly as possible - however most patients will experience some brief discomfort.

​Routine monitoring of your pulse, heart and blood pressure is also started before your anaesthetic. 

Having a General Anaesthesia

When it is time to give you your general anaesthetic the anaesthetist and anaesthetic nurse will firstly check your positioning, monitoring and IV line. You will be given oxygen to breathe from an anaesthetic mask placed over your mouth and nose. 

Most commonly a general anaesthesia is started with an intravenous injection of a strong pain killer and an anaesthetic medicine. Many patients experience a brief sensation of giddiness or floating before rapidly becoming anaesthetised within 20 to 30 seconds. After this the anaesthetist will look after your airway and breathing using a range of possible techniques depending on your individual needs.

During your anaesthetic you will be monitored closely - your ‘vital signs’ such as pulse, blood pressure and so on but also a range of other measures which we use to assess airway, breathing and circulation as well as fluid balance, depth of anaesthesia, body temperature and so on. Most importantly, the anaesthetist is by your side continuously, keeping you safe and responding to any changes during surgery. We keep you anaesthetised for the duration of your surgery either by continuing the administration of your intravenous medications or by giving you anaesthetic vapours to breathe.

Many patients having an anaesthetic for the first time are understandably concerned about the risks of awareness under anaesthesia. ‘Awareness’ in this context means consciousness of surgery, possibly with pain, in a patient who is intended to be unconscious.

Accidental awareness is rare, around 1 patient in 20,000. Modern anaesthetic and monitoring techniques have helped us reduce the risk hugely in most patients, and whilst the risk is not zero, we are happy to strongly reassure our patients that the risk of this during planned surgery is very, very low. We will continue to work hard to keep it that way. 

If you have specific concerns about this, please ask your anaesthetist - they will be happy to explain in detail how we prevent awareness.

Waking Up afterwards
Almost all patients having an operation under general anaesthesia are woken up immediately afterwards either in the operating theatre or post-anaesthesia care unit (PACU).

Anaesthetic drugs affect recall and so it is not unusual for a patient to seem awake and even making conversation immediately after surgery and yet have no recollection of this afterwards. Most patient will remember being in the recovery area, where you will be looked after by our specialist nurses, prior to going back to the ward or day case area. 

It is normal to feel quite drowsy or tired for a few hours after anaesthesia, particularly if you have had an operation lasting more than an hour.

In the immediate recovery period, we assess whether you have any pain or nausea and treat these. We continue to monitor vital signs very closely and we look out for complications of your surgery such as bleeding. When we are satisfied that it is safe you can be discharged from PACU. Some patients having major surgery remain with us in PACU for several hours however most patients stay only for around 30 minutes.

Complications of General Anaesthesia

Most patients will feel very tired and sleepy for some time after a general anaesthetic. For a short operation in a young, fit patient this might be for less than half an hour. For longer anaesthetics and after major surgery it can be several hours. Most patients who had major operations can feel exhausted for several days as the body begins to heal - this is a normal response to surgery or injury.

For older patients, tiredness can be accompanied by temporary memory loss or even confusion. Again this is more likely after major surgery - modern anaesthetic techniques are designed to minimise the chance of this happening to you or a family member.

Sore Throat
When you have a general anaesthesia one of the most important jobs for the anaesthetist is to keep your airway open. 
We do this in a variety of ways using a range of equipment. Each technique can give you a sore throat afterwards which is why this is one of commonest complications of general anaesthesia.

Nausea and Vomiting
Many patients experience sickness, nausea or vomiting after surgery and anaesthesia. Your anaesthetist will assess you and may give you medication to reduce the risk of this.

Dental Damage
Occasionally an injury to your mouth can occur when we are looking after your airway - a bruised lip or even damage to teeth can occur despite our best efforts to be gentle. 

If you already have teeth that are loose, broken or in poor condition, they are much more likely to be damaged during a general anaesthetic. If you have poor dental health please consider visiting the dentist before any planned surgery.

More severe complications of anaesthesia and surgery
As with all medical care, rare complications can happen. Some, like severe allergy or reactions to anaesthetic drugs can arise in any patient. Anaesthetists are trained to recognise these complications and treat them quickly.

Other complications such as stroke or heart attack are more common in patients who already have poor health or significant risk factors, or who are undergoing very major surgery. Your surgeon and anaesthetist will talk to you about this and your care will be planned in such a way as to reduce these risks as much as possible.

It is important to bear in mind that the risks of severe complications for an otherwise reasonably fit patient are very low - much less than 1 in 10,000. This is similar to the risk we take when we take a trip in a car or cross a busy road.

Contributed by Department of Anaesthesia.
Men; Women; Test & Procedures

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