Frequently asked questions

This is a very common fear. Some patients deal with it by choosing to have a regional or local anaesthetic and going without any sedative drugs during the operation or procedure. Other patients who must have a general anaesthetic choose not to have any premed or sedative before the anaesthetic, so that they can remain in control for as long as possible.

Perhaps the best way of dealing with this fear is to think about why you are concerned. Often patients are afraid that they might say or do things when they are unconscious that would embarrass them. You should be reassured that while you are unconscious you cannot talk or move and hospital and clinic staff are professionals trained to treat patients with dignity and respect. Some patients are afraid of dying during anaesthesia or of not waking up. However, the chance of something like that occurring as a result of the anaesthetic is very remote.

‘Twilight sleep’ is a means of dulling consciousness with sedative and painkilling drugs in order to perform minor procedures. These include removal of skin lesions, sewing up of cuts, examination of the stomach or bowel ( endoscopy), and some X-ray procedures where long catheters are inserted into arteries and veins.

Another name for twilight sleep is ‘conscious sedation’. The aim of the technique is to give enough sedatives and painkillers so that the patient is calm, but not so much that the patient loses consciousness. The level of consciousness is monitored by the operator or surgeon continuously talking with the patient, who should be conscious enough to respond. If the patient is not able to respond, this indicates that the level of sedation is too deep and there is a risk of problems with breathing.

If a procedure is complex in nature, as with major cosmetic surgery, or if loss of consciousness is likely, then an anaesthetist should be present to care exclusively for the patient. The surgeon or operator is then able to concentrate on the procedure.

No, you cannot be ‘allergic to anaesthesia’ because an anaesthetic consists of as many as 15 different drugs. Often the phrase ‘allergy to anaesthesia’ is used to describe a side effect from the anaesthetic, such as intense nausea, vomiting, agitation, double vision, sore muscles, etc. These are not allergies, but exaggerations of some of the common side effects of anaesthesia or surgery. You should still mention these complaints to your anaesthetist who can take extra measures to try to minimise them.

However, you could be allergic to one of the drugs used as part of an anaesthetic, and the most likely drug to trigger a reaction is a muscle relaxant. Modern muscle relaxants are less likely to do so, than previously used drugs.

Local anaesthetics are often blamed. Reactions are possible but are uncommon. Most often, the term ‘allergy’ has been applied to the fainting reaction seen after a dentist has injected some local anaesthetic. In fact, the reaction is usually a combination of anxiety and the use of adrenaline mixed in with the local anaesthetic to make it last longer. This does mean that there has been an allergic reaction to the adrenaline.

Allergies to morphine, pethidine or other painkillers are commonly described but again, true allergies are rare. Often, patients use the term ‘allergy’ to refer to vomiting after a medication. This is a common side effect, and not usually a sign of an allergic reaction. Blood products and latex rubber (found in some equipment in the Operating Room) can provoke allergic reactions.

Antibiotics can trigger allergic reactions and your anaesthetist needs to know the details of any previous reactions. Vomiting and abdominal pain are common side effects and usually do not mean that you have an allergy. The occurrence of yeast overgrowth or thrush (in the mouth or vagina), fever, and failure of the infection to resolve are also not true allergic reactions.

In general, allergic reactions are rare. Also, it is important to note that allergies to drugs are not passed on in families. Allergic reactions are caused by presence of antibodies against a specific compound. The existence of antibodies can sometimes be predicted from a patient’s previous response – for example, swelling and hives after administration of an antibiotic. Thus, your anaesthetist needs to know about reactions in the past, even though the same drugs will not be used. Very occasionally, an allergic reaction can occur during the anaesthetic, without any previous reaction or warning.

All anaesthetic drugs work when given in the appropriate dose for a patient. However, it must be understood that patients’ responses to anaesthetics are different and are related to age, sex, weight and degree of illness. Your anaesthetist takes all of these factors into account when calculating the doses of drugs you need.

Individuals who have a high intake of alcohol may require larger doses of anaesthetics. This is because the enzymes in the liver which process alcohol and other drugs may be over-active. Patients who are extremely fat usually need more anaesthetic drugs, since the fat acts like a sponge, drawing drugs from the blood and the brain.

It is extremely rare for patients to talk under anaesthesia. Some patients talk a little while losing consciousness. One anaesthetic drug (sodium thiopentone or pentothal) was popularly known as the ‘truth drug’ and was used in low doses to extract information. People would talk after being given small quantities of this drug in the same way that some people talk after having a few drinks of alcohol. However, the dose of Pentothal required to induce anaesthesia is much greater and the time interval between receiving the drug and becoming deeply unconscious is rarely more than a few seconds.

Patients do not talk during the anaesthetic while they are unconscious, but it is not uncommon for them to do so during emergence from anaesthesia. The first thing most people ask is ‘When are you going to start?’ Thereafter, the conversation usually relates to the surroundings or to some discomfort and often there is no memory of this. Occasionally patients swear or talk of other matters that would normally cause some embarrassment to the patient. Nurses who work in the recovery room are trained to exercise the utmost discretion at these times.

Uncontrolled emptying of the bowel is uncommon during anaesthesia, except in infants. You do not need to have an enema, or medication to clear out the bowel, unless your surgeon specifically orders one. If so, it is because you are having an operation on or near your bowel.

Uncontrolled emptying of the bladder may occur during anaesthesia but should not happen if you empty your bladder shortly before going to the Operating Room. If you normally take a fluid tablet or diuretic, for example, for control of mild high blood pressure – check with your anaesthetist as to whether or not you should take this medication on the morning of the operation. Some anaesthetists believe that it is better not to take a fluid tablet so that their patient is less likely to be troubled by a full bladder either before or after the operation.

Almost all patients receive some intravenous fluids during the anaesthetic and operation. This even applies to patients who are having procedures done under local anaesthesia, such as extraction of a cataract. However, both anaesthetists and surgeons have noticed that it is hard for patients to lie still if they have a full bladder. For this reason, anaesthetists may try to limit the amount of fluid that cataract patients receive.

Other operations require that patients be given large volumes of intravenous fluid and blood. Often these patients have a catheter inserted into the bladder, usually just after induction of anaesthesia. If the bladder is not emptied, then it can contribute to a patient having high blood pressure in the Recovery Room.

In general, you are advised to leave your dentures in safekeeping with a relative or nurse while you have your anaesthetic and operation. If your dentures become dislodged, there is a possibility of interference with your anaesthetist’s ability to clear your airway or to pass an endotracheal tube into your voice box ( larynx). If you are having an operation or procedure on your nose, mouth, or lung passages, then your surgeon may wish you to remove your dentures. There is also a possibility that your dentures might be dropped (and broken) or lost, if they were removed while you were unconscious in the Operating Room.

Occasionally anaesthetists ask their patients to leave their dentures in, especially if they are a firm fit. It may be easier for your anaesthetist to maintain your airway with your dentures in place. Also, if you are having your procedure done under regional block or monitored anaesthetic care, you may be able to keep your dentures in. However, whether or not you do so will depend on your anaesthetist.

Cardiac arrest can and does occur occasionally during anaesthesia, but again, rarely as a result of the anaesthetic. There are multiple causes, including overdose of anaesthetic agents, low blood pressure, and inadequate delivery of oxygen. Rarely, the use of suxamethonium, a muscle relaxant, has been associated with marked slowing of heart to the point where the patient does not appear to have a heart beat. This slowing may occur in children as well as in adults. Usually the heart rate rises quickly again, after a drug (atropine) is given to increase it.

One important point must be made. Except for slowing of the heart from suxamethonium, cardiac arrest rarely occurs suddenly. Although a slow heart rate does not reliably indicate that the heart is about to stop, cardiac arrest does not often occur without warning signs. These signs will be detected by the anaesthetist as he or she monitors the patient.

It is extremely unlikely that you will be awake during a general anaesthetic, but it is possible. There have been descriptions of patients who can recall events that occurred during the operation when they were apparently anaesthetised. This recollection is called awareness. Because the depth of consciousness varies, there is a range of what is remembered. The most common memory is brief, vague, and without pain, and is related to the period at the very beginning or the end of the anaesthetic. Some patients have recalled voices or other sounds; a few remember sounds plus touching; and a very, very few have full sensation of the procedure. These patients have been clearly conscious during surgery, unable to move because of the effects of muscle relaxants, and in severe pain.

Certain procedures carry a greater risk of awareness occurring than others. These include caesarean section (when the amount of anaesthetic is kept purposefully low so as to avoid affecting the baby) and operations for trauma.

However, anaesthetists now recognise that patients may be aware with little outward sign of pain or distress. Although changes in heart rate and blood pressure are two variables used by anaesthetists to alter the depth of an anaesthetic, it is possible for a patient to be aware without any change in these measurements.

Modern anaesthesia demands rigorous attention to the doses of drugs given. Also important is the continuous monitoring of many variables, including aspects of each patient’s responses and concentrations of anaesthetic gases inhaled. Some indication of the depth of anaesthesia can now be measured using a recently available monitor – the BIS (Bispectral Index Monitor).

It is hard to differentiate a patient’s memories of the periods immediately before and after the anaesthetic from those of possible awareness. Some patients may complain of dreams which may or may not mean that they have had awareness. Other patients may believe that they were unconscious for many hours postoperatively until after they reached their room on the ward and yet be able to describe events from the Recovery Room

Patients who have suffered awareness may not be able to describe what happened yet they are very distressed. Reactions may include nightmares, inability to sleep and other sleep disturbances, anxiety, panic attacks and depression. Some patients have reported that they thought that they were crazy, as did relatives, friends and even the Family Doctor. Explaining what probably occurred is the first step in helping these patients to overcome the severe psychological distress and trauma that some have suffered from no one believing that they were awake during the procedure.

You will ‘wake up’ afterwards unless there is a major complication with either the operation or the anaesthetic, or with some underlying condition. Some patients are given sedatives and painkillers that keep them sedated even after emergence from the anaesthetic. These drugs do not prevent you from waking up. Failure to regain consciousness is a sign of brain damage, and can be due to a direct effect of surgery on the brain, a lack of blood or oxygen to the brain, or a major chemical disturbance in the body, such as very low thyroid function. The probability of such a complication is generally considered to equal that of the risk of death during anaesthesia – that is, very low.

Your anaesthetist continuously monitors your blood pressure and the amount of oxygen in your blood. This is to ensure an adequate supply of oxygen to the brain and all other organs. Most often, brain damage is due to an interruption in the planned delivery of oxygen, for example, misplacement of the breathing tube in the oesophagus rather than in the windpipe or unrecognised accidental disconnection of the ventilator. Current monitoring of carbon dioxide (by end-tidal capnography) and oxygen (by pulse oximetry) is intended to provide faster detection of problems and prevention of complications. Your anaesthetist is also prepared to deal with the consequences of surgical problems, such as sudden or large loss of blood.

On rare occasions patients awakening from anaesthesia make amorous advances towards or statements about their doctors and nurses. This may lead to embarrassment (should the patient recall what he or she said) or potential litigation or even criminal charges (should the patient actually believe that sexual impropriety occurred).

It should be noted, however, that the complaints of alleged sexual impropriety after anaesthesia are not specific to any one drug. Similar allegations can be found in the earliest descriptions of anaesthetic practice, more than a hundred and fifty years ago. This type of behaviour is due to temporary loss of some inhibitions, not unlike that occasionally seen with alcohol intoxication. Recovery Room nurses are well aware of the potential for such reactions. They are trained to respond in a manner that does not cause embarrassment to anyone.

Even rarer than damage to all of the brain is the risk of a stroke or damage to part of the brain. A stroke occurs when there is decreased blood flow to a part of the brain, from blockage of a vessel by a clot, by an air bubble, or by haemorrhage. Certain patients are more at risk than others – for example, those undergoing cardiac surgery. Patients who have had a recent stroke or cerebrovascular accident (CVA) probably should not undergo elective operations (unrelated to their brain or blood vessels of the neck) for several weeks. Unfortunately, if a patient suffers a stroke during an operation, the risk of death as a result of the stroke is high.

Contrary to rumour, there is no scientific evidence to show that anaesthetic drugs are toxic to the human brain. If a patient is found to have brain damage postoperatively, then it is likely due to the operation (such as use of the heart-lung machine) or to some underlying condition (such as a blood clot). The role of the anaesthetic in causing brain damage is related to a lack of oxygen, usually from some problem with breathing, and not from a direct effect of the anaesthetic drugs.

This is a common question, especially from pregnant women. Unwanted effects of epidurals vary from mild to serious. Common side effects include:

• A feeling of weakness or heaviness in the legs: This is the effect of the local anaesthetic and depends on which nerves (and how many) are blocked, as well as the strength of the local anaesthetic solution used.

• A fall in blood pressure: This is normally countered by the giving of some intravenous fluid, but occasionally requires drug treatment. The checking of your blood pressure is routine

• Difficulty passing urine: This occasionally requires the temporary passage of a catheter into the bladder (with a small risk of introducing an infection.)

• Backache: This can occur after epidurals for labour but is also common in women who give birth and did not have an epidural.

• Failure: A small area of the pain is not blocked. Sometimes, manipulation of the catheter can help, or the insertion of a second one. Occasionally, the epidural has to be abandoned because of unsatisfactory pain relief.

• Shivering or nausea: This may be related to other drugs which are used, in addition to the local anaesthetics.

Complications include:

• Puncture of the dura: (covering of the spinal cord and fluid) allowing a leak of spinal fluid into the epidural space: This may cause a severe headache, but this can be managed by bed rest, analgesics, and sometimes by having another epidural injection.

• Nerve damage: Sometimes temporary damage may occur to the spinal nerves, but which heals in about 12 weeks. The chance of this occurring is about 1 in every 3000 epidurals given for childbirth. Nerve damage may be caused by nerve pressure during the labour itself and not by the epidural.

• Injection of the local anaesthetic into a blood vessel: This is very rare and can usually be avoided by the use of test doses of the drug.

• Infection or blood clots: These are also rare, providing care is taken to ensure that there is no skin infection and that the patient is not taking drugs to thin the blood.

• Permanent paralysis: This has been reported, but is exceptionally rare. The exact cause is usually not known.

Won’t the epidural increase the change that I’ll need a Caesarean?

In the past, there was a suggestion that epidurals during childbirth decreased a woman’s ability to push and prolonged the labour. This then lead to a forceps delivery or Caesarean section. However, it is now well accepted that there is no significant effect from epidurals on the length of labour or on the chance of needing either a forceps delivery or a Caesarean section.

Modern approaches to the use of epidurals in labour include more active control by the mother over the birth process and the use of very low concentrations of drugs. As a result, many women are able to walk around in labour while still having some relief of the labour pain. If labour is prolonged, for example, because of a large baby, then there may well be a need for a forceps delivery or a Caesarean section. In such cases, the epidural inserted for pain relief during labour can then be used as the anaesthetic for the procedure.

Will the epidural affect my baby?

No, the drugs used for epidurals during childbirth do not have any effect on the baby. Babies born after the use of narcotic (morphine or pethidine) pain relief during labour are much more likely to show the effects of those drugs on their breathing.

There is a small risk of death while anaesthetised. It may be due to a complication of the operation, such as uncontrollable bleeding; to a worsening of some pre-existing disease, such as heart disease; or to a complication of the anaesthetic, usually from a problem with breathing leading to a lack of oxygen. Of these, the anaesthetic plays the smallest part in contributing to the risk of death. In fact, one study compared the risk of death due to surgery with that due to anaesthesia, in a large group of patients who were followed for the first thirty days after their operations. The risk of dying from the operation alone was 1 in 2860 while the risk of dying from the anaesthetic alone was 1 in 185,056. Currently, a fit, healthy, young to middle-aged patient undergoing straightforward elective surgery has a very small chance of dying due to a complication of the anaesthetic, probably less than 1 in 250,000.

When other factors, such as extremes of age, severe illness, and complicated or emergency surgery are added into the equation, then the risk of death increases. However, we know from various studies that the overall risk of death from anaesthesia in most developed countries is still less than 1 in 60,000.

Although this number may seem very high to some, it is a remarkable improvement over the past century, when the risk of death from anaesthesia was about 1 in 100. Since then there has been a steady decrease in the number of deaths directly attributable to anaesthesia. For example, by 1948-52, the overall rate of death from ( ether) anaesthesia was 1 in 820.

Not only has the death rate from anaesthesia (as a primary cause) fallen, but so has the rate of death from anaesthesia as a contributing cause. The risk of death in which anaesthesia was a contributor has decreased to less than 1 in 15000 anaesthetics. Some of the anaesthetic factors that have contributed to a patient dying include incomplete preparation of the patient, inappropriate choice or use of an anaesthetic technique, and inadequate postoperative care.

The improvement in outcome is all the more remarkable considering the range of complex operations now performed and the very ill patients who undergo them. In fact, these operations are possible because of the advances in anaesthesia, such as the introduction of muscle relaxants.

One reason for this decrease in mortality is that the use of new monitoring equipment, such as pulse oximeters and capnography, leads to earlier recognition of problems during the anaesthetic, before the patient’s condition has deteriorated. However, the death rate from anaesthesia was already decreasing before these monitors came into use. Other suggestions are that patients are better prepared for anaesthesia and surgery and that training of both surgeons and anaesthetists has improved. The most likely explanation is that the decreasing death rate is due to a combination of all of these factors.

Of course, the risk of death from the anaesthetic alone must always be kept in perspective with that of the risk of the operation (for which the anaesthetic is given), the risk of dying after the operation, and the risk of various activities of daily life.

There are no age limits for having an anaesthetic. For example, it is now possible to anaesthetise tiny, premature babies for prolonged and major operations. Nor is there any reason why elderly patients should not undergo necessary operations. Developments in drugs, equipment and techniques have made anaesthesia possible and safe for patients of all ages.

Children having surgery fall into one of two groups. The biggest group is children who are otherwise well, apart from the condition for which they need a minor operation. A smaller group consists of children who are quite ill and about to undergo a major operation. In general, children do not suffer from many of the chronic illnesses that afflict adults, such as bronchitis, high blood pressure, heart disease, or the complications from consumption of alcohol and tobacco products. However, even children who are quite well may suffer from asthma (which is becoming increasingly common in western society) and diabetes.

The risk of death in children undergoing anaesthesia is about the same as in a healthy adult. Children under one year of age, however, are at greater risk of complications, especially when cared for by anaesthetists who are not accustomed to managing children.

Most often, problems occur with breathing, either because the airway was not controlled or because breathing is not adequate. Compounding this is the fact that everything happens very quickly in children, including the development of complications.

Some conditions that run in families may cause problems during anaesthesia. Most can be easily and safely managed if the exact cause is known. If it was your grandmother’s sister, then there are several possibilities to consider. When did she have the anaesthetic? If it was many years ago, it might have been at a time when deaths under anaesthesia were more common and anaesthetists less knowledgeable.

If the anaesthetic were more recent, then one needs to know what type of operation she had. How fit was she? Was she ill and having an emergency operation? These are all factors that have some impact on the risks of undergoing anaesthesia and surgery.

If, however, her death was recent and unexpected and she was a fit, healthy woman undergoing a routine procedure, your anaesthetist will want to know as much information as possible about the events. With that information, and current knowledge about inherited diseases, it may be possible to determine the cause of your relative’s death. In addition it may be necessary to order some special tests to help in diagnosing the problem.

The number of people present in the Operating Room depends on the type of institution in which you have your operation or procedure. If your operation takes place in a small hospital or a private clinic, you are looked after by your anaesthetist, your surgeon, and two or three nurses, including one who helps the anaesthetist. If your operation is in a large hospital, in which medical and nursing students are taught, then other individuals could be present during your operation, such as an anaesthetic trainee. If you are to undergo a very complex operation, such as open-heart surgery, then other doctors and technicians will be present, assisting the surgeon and looking after various extra pieces of equipment, such as the heart-lung machine.

Hospitals are notorious for dressing patients in skimpy gowns. Most modern institutions are more aware of the individual’s rights to personal modesty and it is often not necessary to be so stringent about wearing hospital clothing. Children especially resent being made to wear ill-fitting gowns. They should be allowed to wear their own loose-fitting clothes.

Staff in the Operating Room are aware of the need for you to be appropriately covered during surgery and anaesthesia. This is not only for reasons of modesty, but also to prevent loss of body heat. You should try not to feel embarrassed by exposure to hospital and medical staff. To them, in the hospital setting, the human body is an object of their professional expertise. However, at all times they will endeavour to respect your desire for modesty. In particular, they observe any of your dress requirements you might have related to your religious beliefs.

There is really no minimum period during which it is dangerous to have a second anaesthetic. The factors that determine whether you will have a second anaesthetic soon after another one include the need for surgery, how well you recovered from the first procedure, and what drugs were used.

With some older anaesthetics, elimination from all the body tissues took some time and small amounts lingered for several days. This meant that doses of drugs had to be modified when a second anaesthetic was administered.

There are some patients who have needed repeated anaesthetics over many years. Some patients have had more than a hundred. No particular problems have been reported.