DR MARK FREEDMAN M.B.BCh. DA(SA) FFA(SA) PG Cert Clinical Ultrasound

 

Patients' Guide to General Anaesthesia

1. What is a General Anaesthetic?
2. Who gives General Anaesthetics?
3. How does the Anaesthetist give a General Anaesthetic?
4. How Safe is a General Anaesthetic?

1) What is General Anaesthesia?

General anaesthesia is being asleep during surgery. The alternative forms of anaesthesia are:

Regional Anaesthesia

This is when only part of the body is 'frozen' using a local anaesthetic. For example, a whole arm can be put to sleep using an intravenous regional block, or all of the body below the waist can be frozen using a spinal or epidural anaesthetic. These are all types of regional anaesthesia.

Local Anaesthesia

This is where only a small area is frozen e.g. freezing the skin so that a cut can be stitched up. Sometimes 'local' is used to refer to regional anaesthesia as well as truly local anaesthesia.

Sedation

This means that the patient is given a drugs which make the patient drowsy and relaxed, but not completely asleep. Sedation can often be used with local or regional anaesthesia to help the patient relax.

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2) Who gives General Anaesthetics?

Most anaesthetics are given by doctors who, after completing their medical training, take additional training in anaesthesia. Nurses cannot give anaesthetics in Australia, although they do in the USA. In Australia and the UK, doctors who give anaesthetics are called 'anaesthetists'. In the USA, they are called 'anesthesiologists', to separate them from nurse anaesthetists.

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3) How does the Anaesthetist give a General Anaesthetic?

Preparation

First of all, the anaesthetist must know what operation you are having, and some things about you and your health. After reviewing your medical chart, the anaesthetist will ask you a few questions to get details of any problems, and to check on your past experience with anaesthetics. The anaesthetist may also want to perform a brief examination. For example, he may want to have a look at your mouth and teeth to ensure that it would be easy to insert a tube into your windpipe, if this is needed.

Monitoring

Next, the anaesthetist and operating room nurses will ensure that you are properly monitored throughout the anaesthetic. In Australia, this means following the Australian Society of Anaesthetists Guidelines. Most countries have similar recommendations. The routine monitors are:

An ECG (electrocardiogram) monitor

Three sticky pads on your chest connect to a monitor which shows the electrical activity of your heart on a TV screen. This shows how fast your heart is beating, and allows the anaesthetist to pick up problems such as an irregular heartbeat or signs that the heart is not getting enough oxygen.

A BP (Blood Pressure) cuff

This cuff goes round your upper arm. From time to time it will squeeze your arm tight, to find out the pressure of the blood in your arteries. It is important that this is neither too high or too low. An automatic blood pressure machine usually shows four numbers, the high, average, and low pressures with each heartbeat, and the heart rate.

A pulse oximeter

This is a device which goes on a fingertip or earlobe, and measures the amount of oxygen in your blood. It works by detecting a slight change in the blood colour from the usual bright pink to blue as the blood oxygen level decreases, long before this change is visible to the naked eye.

A temperature monitor

This is an electrical thermometer which checks that you are neither too hot nor too cold.

A carbon dioxide monitor

This measures the amount of carbon dioxide in your breath, which shows that you are breathing adequately. It is connected to the breathing tubes coming from the anaesthetic machine.

In addition to all these mechanical monitors, and the alarm systems built into the anaesthetic machine, the anaesthetist remains with the patient from the time the patient goes to sleep until he or she is safe and stable in the recovery room.

Types of General Anaesthesia

Anaesthesia can be divided up into three parts: sleep, absence of pain, and absence of movement.
The simplest anaesthetic consists of a single drug which can produce all these effects for a short period of time. However, it is usual to start with an injection of a drug to put you to sleep and to follow on with anaesthetic gases to continue the anaesthetic. You must be able to breathe during the anaesthetic, so often a tube of some sort will be placed in your mouth. This may be a simple piece of curved hollow plastic called an "oral airway", or a more complicated tube such as a "laryngeal mask airway" or an "endotracheal tube". For some operations, muscle relaxants are required to paralyse the patient during surgery. Often, a powerful analgesic (pain killer) will be added to the mixture.

How do I wake up?

This depends on the type of anaesthetic. Short acting drugs simply wear off. Anaesthetic gases are replaced by air or oxygen. Muscle relaxants, and sometimes the powerful pain killers, may need special drugs to reverse their effects. Once you are sufficiently awake, any tube in your mouth can be removed. You will stay in the Recovery Room for an hour or two until you are completely awake. You should remember not to operate machinery or drive a car for 24 hours after your anaesthetic.

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4) How Safe is a General Anaesthetic?

Modern anaesthetics are extremely safe. Thanks to the excellent modern monitors, better drugs, and the training of modern anaesthetists, anaesthesia is getting safer all the time. For healthy patients, anaesthesia is so safe that it is difficult to measure the degree of risk any more. People with serious heart, lung or other disease, obviously, have an increased risk.

Accidents can still happen, but modern monitors usually ensure that any problems are picked up at an early stage. Older and sicker patients now undergo surgery, but with care, and perhaps with a few days in an Intensive Care Unit, most of them can be got through even major surgery.

There are a few things you can do to decrease your anaesthetic risk:

Stop smoking.

Smoking has been recognised as a cause of postoperative breathing problems since 1944. If you can stop smoking for a few hours, you will be able to eliminate the poisons carbon monoxide and nicotine from your bloodstream. However, it takes between one week and six months for your lungs to show improvement, and your ability to fight infection will remain below normal for one to six weeks. If you need surgery, you should stop smoking NOW.

If overweight, lose weight

Obese patients pose many problems to the anaesthetist, and are more likely to run into breathing problems.

Have a Check-Up

Your surgeon or hospital will probably require this anyway.

Take your medications

In general, if you need medications, especially for serious conditions such as high blood pressure, angina or asthma, you should continue to take them on the day of surgery, with a sip of water. Your doctor will give you specific advice about any medicine for diabetes, and may ask you to stop taking anti-inflammatory drugs such as aspirin or ibuprofen, for a week before surgery.

Obey the "Nil by Mouth" Rule

Many hospitals now allow nothing by mouth for six hours before surgery, except that clear fluids may be taken up to three hours before surgery. Check with your doctor, and do as you are advised. Having an anaesthetic with food and acid still in your stomach may be dangerous.

Make sure your anaesthetist knows about your problems

The anaesthetist will probably have reviewed your chart. Nevertheless, a reminder about allergies to medication, serious illnesses, previous problems with anaesthetics and about loose teeth would be wise.

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Patients Guide to Local & Regional Anaesthesia

Patient's Guide to General Anaesthesia

An Associate of the Northern Anaesthetic Group

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