Anesthesia can be a source of anxiety for many patients, but understanding the basics can help ease concerns.
This page addresses common questions about anesthesia to provide clarity and reassurance. Anesthesia is a medical process that allows patients to undergo surgery and other procedures without pain or discomfort. It comes in various forms, including general anesthesia, regional anesthesia, and local anesthesia.
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Whatever the problem or concern, many patients say “I don’t want to bother the doctor”. Your anaesthetist needs to know any information that might influence the safety of your anaesthetic. You must let him or her know, even if it seems unimportant or embarrassing.
Avoid the following, for a period of 24 hours:
Anaesthetists determine their fees based on the Relative Value Guide. This bases fees on the nature, complexity and duration of the anaesthesia service.
Medicare and private health funds can rebate some or all of this fee.
If the anaesthetist’s fee is not fully covered by Medicare or your health fund, then there is an ‘insurance shortfall’ or ‘out of pocket’ amount, which you will need to cover.
You have the right to ask your anaesthetist about fees and request an estimate.
You have the right to ask your health fund whether you will be covered.
The size of the insurance shortfall or the amount you will be requested to pay varies greatly on your health fund.
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These are questions for you to ask your anaesthetist before your operation, although you may not want to use them all.
People have fears about all sorts of things in life, especially those they don’t understand. Many people have a fear of anaesthetics – hence the reason for this website! Many of the fears about anaesthesia come from snippets of incomplete information or from sensationalist press reports. All have a basis in fact, but need to be explained in context and in detail. It is appropriate for you to discuss your concerns about any of these matters with your anaesthetist.
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:
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.
Many symptoms and complaints have been ascribed to anaesthesia over the years, often by well-meaning surgeons, nurses, family doctors, or helpful relatives. This most often occurs when the real cause of the problem is not obvious. In many cases the complaint is not actually related to the anaesthetic.
However, if you have a concern, you should talk to your anaesthetist and seek an explanation.
It is not uncommon for patients to feel stressed at the time of anaesthesia and surgery. Feeling stressed before going to the hospital is to be expected as it is not an event which we look forward to, nor do most of us experience it often enough that we become more tolerant. Such stress can be managed and made less likely to result in after-effects. You should discuss any concerns you might have with your surgeon, your anaesthetist and your family doctor. Above all, find out as much as you can about your illness and operation and take a role in your own management.
Occasionally, a patient may complain of localised pain in the back or in a joint. The usual cause is a decrease in muscle tone and manipulation of the joints while the patient was unconscious. Certain operations require patients to be placed in positions in which they would not normally find themselves. Patients at increased risk of joint pain are those with arthritis and those undergoing long procedures. A quick check of the range of motion of your neck, arms and hips may go a long way to avoiding this sort of discomfort. After the anaesthetic, rest, mild painkillers, and the application of warmth will ease this discomfort.
If you are a smoker or suffer from chronic bronchitis, it is not unusual for your cough to be a little worse after the anaesthetic. This is for two reasons. First, nicotine suppresses the normal mechanism by which the lungs expel mucous. During the course of the anaesthetic, some of the effect of the nicotine wears off, allowing the lungs to start to recover. Second, the breathing (endotracheal) tube and the anaesthetic gases may act as irritants in certain patients, provoking cough.
The best treatment for a smoker is to give up smoking at least six weeks before the anaesthetic. Patients with chronic bronchitis may benefit from chest physiotherapy, and some may need adjustment of their bronchodilator medication, as well as a course of antibiotics. Both groups of patients may benefit from having active physiotherapy postoperatively.
These may be related to the use of a specific drug, called ketamine. This drug has particular attributes, which makes it extremely useful in patients with severe burns and other life-threatening injuries. Ketamine is widely known to cause a range of hallucinations that seem to be worse in adults. Sometimes the hallucinations can be minimised by using another drug such as Valium (diazepam).
Patients may complain of a sore throat and hoarseness after anaesthetics for which insertion of a breathing tube (tracheal intubation) was required. These problems are generally short-lived.
Other patients may complain of persistent hoarseness after an anaesthetic. When examined, they are occasionally found to have a vocal cord that does not work, secondary to damage of the nerve to the larynx, the recurrent laryngeal nerve. This damage is often blamed on the anaesthetist from use of the laryngoscope and insertion of the breathing tube. However, this is rarely the cause of such damage, except when patients are ventilated (breathed for with a machine) for many days or weeks, as in the intensive care unit. More commonly, damage to the nerve is the result of surgical manipulation or trauma, which may occur during thyroid or other neck operations. Other permanent voice changes are also more often due to surgical damage to another nerve, the external laryngeal nerve, than to the anaesthetic.
Families may notice that after an operation, a relative is disoriented, has undergone a minor personality change, or has suffered a loss of memory. This is especially common in the frail elderly and is difficult to predict and largely impossible to prevent. In fact, some changes may be due to the fact that the patient has been taken from familiar surroundings into the disruptive environment of the hospital, where noise is common and sleep is disturbed.
Family and friends should treat the patient as normally as possible, and be reassured that the condition is probably temporary. Usually patients recover completely, once they return to their home and their normal routines. The patient themselves will have little or no memory of the events which occur during this period, but you may wish to discuss this with the anaesthetist or surgeon.
Typically, patients complain the day after a general anaesthetic that they have pain in the muscles of the upper body, chest wall, back and occasionally the lower body. These sensations are like those experienced during the onset of influenza, although some patients complain about feeling as though they were ‘run over by a truck’. Others have complained that they had difficulty breathing or lifting the head from the pillow, or unable to move. Commonly, these patients are young, have undergone minor procedures such as dental extractions, and went home on the day of the procedure, with resultant activity. Curiously, the problem does not affect children. The treatment is rest and mild analgesics. Symptoms should resolve after a few days.
The usual cause of this discomfort is termed ‘sux myalgia’ and results from the use of suxamethonium, a muscle relaxant. One might ask why this drug is used when it causes such pain (as well as other complications). Suxamethonium produces rapid onset of muscle relaxation, which is important when the anaesthetist needs to obtain rapid control of a patient’s breathing. This may be the case in an emergency, when the patient has a full stomach and is at risk of regurgitating the stomach contents up the oesophagus and into the lungs.
Some patients may report that their hair has fallen out after an anaesthetic. Others say that their hairdresser tells them that the “perm” has not worked because of the anaesthetic. There is no known relationship between these types of complications and any of the anaesthetic drugs. The effects are more likely due to stress and can occur as a result of stress without anaesthesia or surgery.
A sore throat is quite common after having an anaesthetic or operation. The soreness may also affect the tongue. Some of the soreness may be due to not being able to drink before the operation and then breathing dry anaesthetic gases. Many patients think that the breathing tube causes the sore throat. It is true that patients who have an endotracheal tube inserted are more likely to have a sore throat. Modern endotracheal tubes are much less irritating than the ones that were used in the past, and a lubricant is often used to make actual insertion of the tube easier. However, the soreness is probably more related to use of the laryngoscope, the instrument used by your anaesthetist to see where to place the tube. A sore throat is more likely in those patients in whom there were difficulties in seeing the larynx, such as those with prominent teeth, a small lower jaw or a short neck. The soreness usually passes in a day or two and can be eased by a mild analgesic such as paracetamol (acetominophen), aspirin or a soothing throat lozenge.
The tongue may be bruised during the insertion of the endotracheal tube. This bruising is usually due to pressure from the laryngoscope. Occasionally the tongue may become sore and swollen after an oral airway has been used. In this case, the tongue may have been bunched up under the airway. As with a sore throat, a sore tongue usually only lasts for a day or two.
Although anaesthesia is safer than in the past, complications do occur. One large study showed that about 10 per cent of patients experienced some problem during or after the anaesthetic. The complication could be as major as brain damage (but extremely rare) or as minor as muscle soreness (but more common). The most frequent complications are nausea, vomiting and sore throat. Anaesthetists are trained to recognise and manage complications quickly, and many will undergo part of this emergency training in simulators, much like airline pilots do.
The accompanying lists describe some of the complications that may occur during or after an anaesthetic. This lists are selective and do not include all complications.
Allergy to anaesthetic drugs is rare. The severity of allergic responses can range from mild (wheeze and rash) to severe (life-threatening anaphylactic reactions). As well as anaphylactic or immune-related reactions, some patients develop anaphylactoid reactions. Although this type of reaction does not involve antibodies, these reactions may also be severe, through the release of histamine.
If a patient is undergoing a general anaesthetic and is unconscious, the signs of an anaphylactic reaction may vary. The diagnosis is made by the recognition of such things as low blood pressure, wheezing, hives, rash, swelling (oedema) around the eyes or in the mouth and throat, and breathing difficulties.
Anaesthetists are trained to recognise and treat allergic reactions in the Operating Room. However, an important part of treatment of any allergic reaction is prevention. If you have any history of swelling of the face or generalised itching, you should let your anaesthetist know. Skin testing can be used to identify allergens (substances that cause allergic reactions). This may be helpful in identifying the particular drugs causing a reaction in those patients who apparently are ‘allergic to anaesthesia’.
The prevention of latex allergy includes removing all latex containing materials from the Operating Room, where possible. Most Operating Rooms have a special equipment kit for use in caring for latex-allergic patients.
Some patients may react abnormally to one or more drugs used during anaesthesia. Usually there will be some warning of this from prior experience, or knowledge of the particular condition or health of the patient. Occasionally, however, there is little warning, and the anaesthetist must be constantly alert to the potential for abnormal reactions.
Some patients develop complications because of the interaction of specific anaesthetic drugs with a pre-existing condition. There are very few ‘anaesthetic diseases’, that is, specific diseases for which anaesthetic drugs must be carefully selected so as to minimise the risk of problems. However, these diseases do exist. The following brief description of two of these conditions is not meant to replace a more definitive source of information.
First recognised in Australia in 1960, malignant hyperthermia or malignant hyperpyrexia (MH) consists of an unexplained rise in body temperature and muscle rigidity during anaesthesia, due to a massive increase in metabolism. Consumption of oxygen and production of carbon dioxide also rise markedly. Predisposition to malignant hyperthermia is an inherited condition and occurs in about 1 in 40,000 patients. MH is triggered after exposure to specific anaesthetic drugs – the volatile anaesthetic agents (such as isoflurane) and suxamethonium. Triggering may occur on the first exposure to these drugs or even after repeated and uncomplicated anaesthetics.
Treatment of an episode of MH consists of stopping the triggering drug, stopping the operation if possible, and administering a drug called dantrolene. This is the only specific drug treatment for this syndrome; without it, about half of all patients who suffer a malignant hyperthermia reaction will die. Other treatment is also important, in the form of extra oxygen, cooling, and resuscitative drugs and fluids.
The principal test for MH is one performed on a piece of biopsied muscle, although unfortunately some tests appear to show that the patient has the condition when in fact the patient does not. (This is known as a ‘false positive’ test result.) As more genetic patterns are recognised in families with MH, some susceptible patients may be diagnosed using genetic marking. The patient and close relatives should all be tested. A patient who has had an MH reaction or a positive test should obtain some form of Medic Alert notification and carry this at all times.
If a patient with known MH requires an operation, then the Operating Room should be specially prepared. No volatile anaesthetic agents should be used in the room for 12 hours and, if possible, the patient should be scheduled as the first case of the day. A ‘safe’ technique consists of avoiding the known triggering agents and is not difficult to achieve. Drugs that are considered ‘safe’ include nitrous oxide, thiopentone, propofol, midazolam, narcotics, muscle relaxants such as curare or vecuroniun, and any of the local anaesthetic drugs. The patient’s condition, including temperature, should be carefully monitored as with any general anaesthetic. This monitoring should continue into the postoperative period. Some patients have been reported to have a reaction after a ‘safe’ anaesthetic, but these reactions apparently have not been severe.
Plasma cholinesterase deficiency
Plasma cholinesterase deficiency or pseudocholinesterase deficiency (PChD) is an enzyme deficiency that affects the metabolism of some anaesthetic drugs, thus lengthening their action. These drugs include certain types of local anaesthetic agents and suxamethonium. It is important to remember that having PChD does not mean that the patient is ‘allergic’ to these drugs, but simply that the drug takes longer to wear off.
If a patient with PChD is given suxamethonium, then the muscle relaxation from the drug may last for several hours, instead of a few minutes. During this time, the patient is unable to move or breathe spontaneously, and requires artificial ventilation. sedation, which makes the period of the profound weakness less unpleasant, is used while the action of the drug wears off.
PChD may be inherited and is found in less than 0.01 per cent of the population. The condition may also occur in patients with liver failure and certain tumours, as well as in those exposed to specific drugs, such as ecothiopate, and to certain insecticides. Some women at the end of pregnancy may develop a very mild form of PChD which disappears after birth of the baby. The enzyme deficiency can be confirmed by a special blood test.
It is possible to suffer a heart attack during the course of an anaesthetic. However, if one does occur, it is more likely to be on the second or third day after the operation. The risk of having a heart attack or myocardial infarction (MI) is very low, but patients who have suffered an MI in the past should consider not having elective surgery during the following six months.
Other patients with severe hardening of the arteries of the neck (carotids) are not only at risk of myocardial infarction, but also of a stroke (cerebro-vascular accident or CVA). Again, this is a rare but serious complication of anaesthesia.
Laryngospasm
Sometimes, especially at the beginning or end of an anaesthetic, the vocal chords in the larynx (voice box) may close, making it very difficult for any air or oxygen to pass to and from the lungs. The condition can be likened to “choking”, and if allowed to continue, can result in a lack of oxygen entering the bloodstream. Anaesthetists are trained to deal effectively with this potentially serious complication, sometimes requiring the emergency administration of drugs to relax all muscles.
Difficult airway
Some patients have particular anatomical features of their neck and mouth that make management of their airway, or intubation difficult. The anaesthetist will make a judgement as to the likelihood of such a problem, during the pre-anaesthetic assessment. If he or she suspects that there may be a difficult airway, the anaesthetist will ensure that additional specialised equipment and expert assistance is immediately available.
Bronchospasm
Bronchospasm refers to a narrowing of the major airway branches in the lung. The result is similar to severe asthma with wheezing. When it occurs, the flow of air is reduced, especially when breathing out (exhaling). Commonly, bronchospasm is easily treated by deepening the anaesthetic, removing the stimulus, or giving drugs such as salbutamol, aminophylline, or steroids. For particularly severe reactions, adrenaline may be required.
Patients with asthma or chronic obstructive lung disease (COLD) and smokers may develop wheezing or bronchospasm. Bronchospasm may also occur in previously healthy patients during an allergic reaction due to drugs or blood products or after aspiration of gastric contents. Bronchospasm may also occur after such procedures as insertion of the breathing tube.
Pneumothorax
In this condition, air (or another gas) enters the normally empty space between the lungs and the chest wall. If not detected and treated, this can be life threatening as the gas expands and compresses the heart and the major blood vessels in the chest, preventing blood from entering or leaving. Most often a patient has a small but undiagnosed leak in the lining of the lung. This leak increases with the use of artificial ventilation. The problem may occur spontaneously in those with congenital swellings (bullae) of the lungs, patients with chronic lung disease and emphysema, or in asthmatics. In addition, the lining of the lung may be accidentally punctured by some injections around the neck or in the chest region.
Certain patients are at increased risk of having blood clots – for example, those taking oral contraceptives or hormone replacement. Certain surgical procedures also increase the risk of clots, such as operations that last several hours or are on the lower part of the body. In general, anaesthetics do not increase the risk of having a blood clot.
Some operations may lead to a decrease in intellectual ability, for example, after major brain or open heart surgery. Other patients are at risk because of pre-existing medical conditions, such as age-related loss of memory. Elderly patients, particularly those with progressive heart disease, high blood pressure or a history of minor strokes may suffer permanent changes after anaesthesia. This may be a result of a change in critical blood supply to certain parts of the brain, altering specific chemicals in the brain.
Blood supply to the brain may be subtly altered by a decrease in the amount of carbon dioxide in the blood and by slight changes in blood pressure. Many anaesthetic drugs have side effects which can alter blood flow, although modern drugs are less likely to produce these effects.
On rare occasions, patients have suffered brain damage due to lack of oxygen delivery to the brain. Even though all aspects of the anaesthetic are carefully monitored during an anaesthetic, sometimes problems can occur.
Patients often develop a small bruise at the site of insertion of the intravenous cannula, in the back of the hand, in the forearm near the wrist, or in the bend of the elbow. These bruises can become painful and may take a week or so to resolve. Elderly patients, and those with fragile skin and veins, bruise more easily and the bruise often takes longer to disappear.
Although anaesthetists are very careful to avoid contact with the teeth, damage may occur when metal or hard plastic instruments are used to maintain an open airway, to help with insertion of the breathing ( endotracheal) tube, or to suck out secretions from the mouth and back of the throat. In most cases, damage occurs at the time of tracheal intubation, in about one in every 1000 intubations. Dental damage may also occur when a patient bites down on an oral airway during recovery from anaesthesia. The force generated is enough to break both natural and restored teeth and has been noted in between a quarter and a half of all reported cases of dental damage.
Although human teeth are very strong, they become more brittle with age. Just as you may chip a tooth while eating, the same may occur during intubation. Cosmetic dental work, with veneers, crowns or bridges, is a particular concern, as these structures are not as strong as natural teeth.
If you have had dental work, especially on your front teeth, then you should inform your anaesthetist and discus any concerns you might have. You should also point out any teeth which are loose. You may be able to lessen the risk of damage by having an alternative technique to general anaesthesia, such as regional anaesthesia (if appropriate). However, in some cases, general anaesthesia with an endotracheal tube is necessary. Attempting to avoid tracheal intubation, for example by using a mask, may lead to other complications, such as aspiration of stomach contents into the lungs. Some anaesthetists try to prevent dental damage by removing the oral airway before their patients regain consciousness and replacing it with a soft short tube placed in one nostril. (This is known as a nasal airway.)
Should any of your teeth be damaged or lost during an anaesthetic or operation, or while you are in the recovery room, you will need emergency treatment. This includes re-insertion of the tooth (if appropriate) and emergency dental consultation (if available). Great effort should be made to locate any missing teeth and you may need to have a chest X-ray to ensure that you have not inhaled the tooth. If you have and the tooth is not removed from your lung, then there is a high probability of pneumonia.
Similarly, children may undergo anaesthesia when their first teeth are about to be lost. These first teeth are very easily dislodged, and you should tell the anaesthetist which teeth are loose. Sometimes parents request the anaesthetist remove a tooth that is about to fall out!
Adults with loose teeth should see a dentist, if possible, before their anaesthetic. The same suggestion applies if any of the teeth are badly broken or decayed. In addition, professional dental cleaning is recommended for patients who have gum disease, especially for those patients who are scheduled to have a major operation.
Various types of eye damage may occur. The cornea or surface of the eye may be scratched when the eyelids are not completely closed, particularly if the face is covered with drapes or towels. Some anaesthetists choose to secure the eyelids closed with tape – although certain patients may develop skin reactions and others may complain of loss of eyelashes after removal of the tape. Other anaesthetists choose to insert a lubricating ointment into the eye – although eye infections have been reported if the ointment is contaminated. Some patients have complained of blurring of vision for a few hours postoperatively, because of the residual ointment. However, corneal damage may occur even if the eye is lubricated and taped shut. The presence of make-up, such as mascara, is potentially hazardous.
Blindness after both general and regional anaesthesia is rare, but it can occur. Loss of vision may result from pressure on the eye. It may be that the arteries at the back of the eye (retina) become compressed, thus depriving the eye of oxygen. Smokers are more at risk than are nonsmokers, because nicotine constricts or narrows arteries, further depriving the eye and the brain of oxygen. Temporary blindness may also occur after spinal anaesthesia for resection of the prostate gland in men. This is due to the effect of a special chemical in the fluid placed in the bladder by the surgeon during the course of the operation.
postoperative nausea and vomiting (PONV) is one of the most common postoperative complications, affecting up to as many as 40 per cent of patients. The patient most likely to vomit is a young, non-smoking, overweight woman who has undergone gynaecological surgery. Also at risk are patients with a history of PONV and those with a history of motion sickness (in a car or aeroplane or at sea).
All anaesthetic agents have been blamed, with opiates or narcotics most often implicated. Indeed, the anaesthetic is most often blamed for all PONV, even when nausea and vomiting occurs days after the operation and all traces of the anaesthetic have disappeared from the body.
Other factors may contribute, including:
Many of these factors can be avoided or treated, to reduce the chance of postoperative nausea and vomiting occurring. Your anaesthetist makes all attempts to ensure that you do not suffer from PONV. However, complete prevention of this complication is not possible.
Almost any nerve can be damaged. Nerves of the face may be damaged by pressure from the anaesthetic breathing circuit or from the anaesthetist’s fingers holding the facemask on and the chin forward. The most common nerve injury is to the ulnar nerve at the elbow, from compression against a hard surface. In general, the prevention of nerve damage is by careful positioning and padding of the patient during anaesthesia. In the past, the cause of postoperative nerve damage was always thought due to improper positioning of the patient; however, some patients who develop nerve damage have been found to have a pre-existing problem.
Sometimes, instead of passing the breathing (endotracheal) tube through your mouth, your anaesthetist chooses to pass it into one nostril and down the back of the throat and into your voice box ( larynx). This change in route may still involve insertion of the laryngoscope into your mouth, so that your anaesthetist can see where he or she is placing the tube. Nasal intubation is normally used for operations around the face and mouth.
Insertion of the tube through the nostril often results in some bleeding from the nose after the tube is removed. This bleeding normally stops after a few minutes, although seeing the nose bleed may be distressing to family members.
Anaesthetics are not treatments in themselves. Patients do not go into hospital to have an anaesthetic, but to have an operation for which they need an anaesthetic. As a result, any complication is usually regarded as an unwanted effect. Many anaesthetists recognise that most problems in anaesthesia relate to a complex set of factors, including the patient’s condition, the actions of those who provide care, equipment, and the environment in which the operation is performed – the hospital, and the regulatory agencies. Thus, perfect outcome after anaesthesia is unlikely to be achieved in every case.
Patients, too, have changed their thinking about anaesthetics. When any operation carried a high risk of death from shock, blood loss, and infection, patients who did survive counted themselves lucky. For example, Samuel Pepys, the famous writer of the 1600s, celebrated the anniversary of his surviving an operation to remove a stone from his bladder. Today, with certain procedures described as ‘virtually problem-free’, patients are more likely to speak up about any complaint that they have.
One factor that makes it hard to determine if patients have suffered even minor complications is the difficulty with follow-up. Many patients are discharged home the same day. Patients who have had major operations may be sent to a smaller facility to recover. It is therefore more difficult for anaesthetists to see patients postoperatively. Anaesthetists are dependent on patients letting them know if there has been an unexpected problem, or upon the surgeon to relay such information. Unfortunately, such communication frequently does not take place. In some facilities, patients who remain in hospital are routinely visited or given questionnaires about their anaesthetic care. Other facilities telephone patients within a day or two of the anaesthetic and operation to determine how things have gone, or patients are given telephone numbers they can use 24 hours a day in order to contact an anaesthetist.
Another factor to remember is that complications rarely result from the anaesthetic alone. As stated above, patients do not come into hospital to have an anaesthetic but to have an operation. In addition, the patient may have any number of medical problems before the operation. Large studies that have followed-up patients after anaesthesia and surgery have shown that the two factors which are responsible for approximately 90 per cent of deaths postoperatively are the patient’s disease(s) and the surgical operation.
Although an anaesthetist may be able to influence a patient’s condition through careful preoperative assessment and management, the same is not possible for the surgical factors. For example, the probability of complications increases with the duration of the surgical procedure. If an operation takes longer than three to four hours, then the patient has a slightly increased chance of developing heart and lung problems. As a general rule, few patients die from the anaesthetic alone. Only about 10 per cent of patients suffer some other kind of anaesthetic-related complication, nearly all of them minor.
Although the anaesthetic may not be the major contributor to how you feel after an operation, if you think something has gone wrong with your anaesthetic, then it is very important to sort this out right away. Don’t wait twenty years until you suddenly find that you need to have another operation.
Ask to speak to your anaesthetist or to another anaesthetist. Ask to have the anaesthetic record reviewed and, if possible, get the anaesthetist to show you the record and explain what each notation means.
If the anaesthetist suggests that you have special tests, then have them done. These tests could include those for allergy; for plasma (or pseudo) cholinesterase; or for malignant hyperthermia. Once the results are available, ask to have a copy that you may keep in your purse or wallet, or in the glove compartment of your car.
If your test results are positive, then your anaesthetist may recommend that you obtain a Medic-Alert bracelet or some similar type of medical information system. These kinds of alerting and informing systems are particularly useful if you become incapacitated and are unable to explain your condition to the anaesthetist or to other doctors.
Above all, do not be afraid to find out what happened. Some patients worry for years that ‘something dreadful happened to me during my anaesthetic’, and put off having another needed operation. Visiting an anaesthetist and having the previous worrying events explained and demystified has freed these patients from unnecessary concerns.
