Safety in Anaesthesia: Risks and Benefits

Safety in Anaesthesia: Risks and Benefits

Anaesthesia has made much of today’s surgery possible, and has brought great benefits. Today, joints can be replaced, organs can be transplanted, and diseased tissue can be removed with a high degree of comfort and safety. The benefit of anaesthesia is that it will remove pain and sensation. This benefit needs to be weighed against the risks of the anaesthetic procedure and the drugs used. The balance will vary from person to person. It is difficult to separate these risks from those of your operation or procedure and your general health. Everyone varies in the risks they are willing to take. Anaesthetists and patients may also hold different views about the importance of risk.

The anaesthetist may use many drugs or combinations of drugs. The more complicated the anaesthesia and surgery are, the more chance there is of complications and side effects (see below).

It is the responsibility of the anaesthetist to advise you on what anaesthetic techniques will give you greatest benefit and reduce these risks as far as possible. Making these decisions is difficult, but your anaesthetist will want to help you so that you can make the choices that are right for you.

The risk to you as an individual will depend on:

  • whether you have any other illness

  • personal factors, such as whether you smoke or are overweight

  • surgery which is complicated, long or done in an emergency.

Side effects and complications of anaesthesia

Anaesthetic risks are thought of in terms of side effects and complications.

Side effects are secondary effects of drugs or treatment. They can often be anticipated but are sometimes unavoidable. Almost all treatments (including drugs) have side effects of some kind. Unpleasant side effects do not usually last long. Some are best left to wear off and others can be treated. Examples would be a sore throat or sickness after a general anaesthetic.

Complications are unexpected and unwanted events due to a treatment. Examples would be an unexpected allergy to a drug or damage to your teeth caused by difficulty in placing a breathing tube. The risk of something happening to one in 10 people means that it will not happen to nine out of 10 people.

  • If something is very common, this mean that about one in 10 will experience it

  • Common means about one in 100

  • Uncommon means about one in 1,000

  • Rare means about one in 10,000

  • Very rare means about one in 100,000

  • GA refers to General Anaesthesia

  • RA refers to Regional Anaesthesia

Very common and common

Feeling sick and vomiting after surgery (RA & GA)

Some operations, anaesthetics and pain-relieving drugs are more likely to cause sickness (nausea) than others. Sickness can be treated with anti-vomiting drugs (anti-emetics), but it may last from a few hours to several days.

Sore throat (GA)

If you have had a tube in your airway to help you breathe, it may give you a sore throat. The discomfort or pain lasts from a few hours to days and can be treated with pain-relieving drugs.

Dizziness and feeling faint (RA & GA)

Your anaesthetic may lower your blood pressure and make you feel faint. This may also be caused by dehydration (when you have not been able to drink enough fluids). Fluids or drugs (or both) will be given into your drip to treat this.

Shivering (RA & GA)

You may shiver if you get cold during your operation. Care is taken to keep you warm during your operations and to warm you afterwards. A hot air blanket may be used. However, shivering can happen even when you are not cold, due to the effects of anaesthetic drugs.

Headache (RA & GA)

There are many causes of headaches, including the anaesthetic, the operation, dehydration and feeling anxious. Most headaches get better within a few hours and can be treated with pain relieving medicines. Severe headaches can happen after a spinal or epidural anaesthetic. If this happens to you, your nurses should ask the anaesthetist to come and see you. You may need special treatment to cure your headache.

Itching (RA & GA)

This is a side effect of opiates (such as morphine), but can be caused by an allergy (for example, to drugs, sterilising fluids or stitches or dressings). If you have itchiness, it can be treated with other drugs.

Aches, pains and backache (RA & GA)

During your operation you may lie in the same position on a firm operating table for a long time. Great care is taken to position you, but some people still feel uncomfortable afterwards.

Pain (RA & GA)

Drugs may cause some pain or discomfort when they are injected.

Bruising and soreness (RA & GA)

This can happen around injection and drip sites. It may be caused by a thin vein bursting, movement of a nearby joint, or infection. It normally settles without treatment, but if the area becomes uncomfortable, the position of the drip can be changed.

Confusion or memory loss (GA)

This is common among older people who have had an operation under general anaesthetic. It may be due to several causes. It is usually temporary, but may sometimes be permanent.

Chest infection (GA)

A chest infection is more likely to happen to people who smoke, and may lead to breathing difficulties. This is why it is very important to give up smoking for as long as possible before your anaesthetic.

Bladder problems (RA & GA)

After certain types of operation and regional anaesthesia (particularly with a spinal or epidural), men may find it difficult to pass urine, and women tend to leak. To prevent problems, a urinary catheter may be inserted at a suitable time.

Muscle pains (GA)

These sometimes happen if you have received a drug called suxamethonium. This is a muscle relaxant which is given for emergency surgery when your stomach may not be empty.

Uncommon side effects and complications

Breathing difficulties (RA & GA)

Some pain-relieving drugs can cause slow breathing or drowsiness after the surgery. If muscle relaxants are still having an effect (have not been fully reversed), the breathing muscles may be weak. These effects can treated with other drugs.

Damage to teeth, lips or tongue (GA)

Minor damage to your lips or tongue is common. Damage to your teeth is uncommon, but may happen as your anaesthetist places a breathing tube in your airway. It is more likely if you have weak teeth, a small mouth, a stiff neck or a small jaw.

An existing medical condition getting worse (RA & GA)

Your anaesthetist will always make sure that you are as fit as possible before your surgery. However, if you have had a heart attack or stroke, it is possible that it may happen again – as it might even without the surgery. Other conditions such as diabetes or high blood pressure will also need to be closely monitored and treated.

Awareness (GA)

Awareness is becoming conscious during some part of an operation under general anaesthetic. It happens because you are not receiving enough anaesthetic to keep you unconscious. Monitors are used during the operation to record how much anaesthetic is in your body and how your body is responding to it. These normally allow your anaesthetist to judge how much anaesthetic you need to keep you unconscious. If you think you may have been conscious during your operation, your anaesthetist should be told about it as soon as possible. He or she will want to know, to help both you and future patients.

Rare or very rare complications

Damage to the eyes (GA)

Anaesthetists take great care to protect your eyes. Your eyelids may be held closed with adhesive tape, which is removed before you wake up. However, sterilising fluids could leak past the tapes, sheets or drapes or you may rub your eye as you wake up after the tapes have been removed. These could cause damage to the surface of your eye, which is usually temporary and responds to drops. Serious and permanent loss of vision can happen but it is very rare.

Serious allergy to drugs (RA & GA)

Allergic reactions will be noticed and treated very quickly. Very rarely, these reactions lead to death even in healthy people. Your anaesthetist will want to know about any allergies in yourself or your family.

Nerve damage (RA & GA)

Nerve damage (paralysis or numbness) can be caused by a needle when performing a regional anaesthetic or can be due to pressure on a nerve during an operation. It varies with the type of anaesthetic you have but is generally rare or very rare. Most nerve damage is temporary, but in some cases damage is permanent.

Death (RA & GA)

Deaths caused by anaesthesia are very rare. There are probably about five deaths for every million anaesthetics given.

Equipment failure (RA & GA)

Vital equipment that could fail includes the anaesthetic gas supply or the ventilator. Monitors give an immediate warning of problems, and anaesthetists have immediate access to backup equipment.

Adapted from the AAGBI ‘Anaesthesia Explained’ information booklet