Medical emergencies in the dental practice

Transcription

1 Periodontology 2000, Vol. 46, 2008, Printed in Singapore. All rights reserved Ó 2008 The Author. Journal compilation Ó 2008 Blackwell Munksgaard PERIODONTOLOGY 2000 Medical emergencies in the dental practice MARK GREENWOOD Medical emergencies can be alarming to any clinician but these situations are less alarming if proper preparation has been made. Medical emergencies occur in dental hospital practice more frequently than in dental practice, but in similar proportions in terms of their nature (5). A thorough patient history can draw the practitionerõs attention to potential medical emergencies that could occur (36). It is particularly important in the history to enquire about known allergies or adverse reactions to medication so that these can be avoided (9). Good methods of practice can prevent many emergencies, for example prompt treatment of a diabetic patient at a predictable time thereby avoiding hypoglycemia. In one study (4) there was a perceived need for further training among dental practitioner respondents to a survey on training in medical emergencies. Dental procedures themselves can jeopardize the airway, which must therefore be adequately protected. Patients with pre-existing medical conditions, such as asthma or angina, will usually be taking prescription medications (34) and the practitioner should always check that these are readily available and have been taken on the day of treatment (16). Patients who have an asthma attack and who have not brought their normal medication will not be helped significantly by oxygen alone (because of the bronchoconstriction). It is therefore vital that patients with asthma bring their inhalers with them or that they are available in the emergency drug box. The various national formularies, including the British National Formulary, list the drugs to be included in an emergency box for the dental surgery (14). These are shown in Table 1. Similar documents may be available in different countries (1, 18, 23, 24). A further addition to the list in the British National Formulary is the benzodiazepine antagonist, flumazenil. The common emergencies that may occur in dental practice will be discussed in turn and refer to adult patients. In all these situations the basic principles of resuscitation should be remembered, i.e., attention to the Airway, Breathing, and Circulation (A, B, C) (7). Key points in the management of medical emergencies in practice are given in Table 2. Routes of drug administration are also important (10) and wherever possible alternatives are given. Drugs are continually being developed that may be administered by more ÔconvenientÕ routes (43). Loss of consciousness The most common cause of loss of consciousness in a dental practice is vasovagal syncope (fainting). If the recovery is not rapid other possibilities should be considered, such as myocardial infarction, bradycardia, heart block, stroke, hypoglycemia, or anaphylaxis. If the cause of collapse is uncertain the following steps should be taken. The patient should be laid flat, with the legs raised in vasovagal syncope this will usually result in rapid recovery. A clear airway should be ensured and maintained and the pulse should be checked. Absence of pulse indicates cardiac arrest and cardiopulmonary resuscitation (CPR) should start immediately. If there is a palpable pulse, hypoglycemia is a possibility and the patient should be treated as detailed later in this paper. Hydrocortisone sodium succinate should be given in a dose of 200 mg intravenously. The management of a collapsed patient where the collapse is of unknown cause is summarized in Table 3. Fainting (vasovagal syncope) Fainting is the most common medical emergency encountered in dental practice. It is predisposed to by factors such as pain and anxiety. 27

2 Greenwood Table 1. Contents of the emergency drug box Adrenaline (epinephrine) 1 in 1,000 Aspirin 300 mg Chlorphenamine (10 20 mg) Diazepam (5 mg ml) Glucagon (1 mg) Glucose intravenous infusion (20% 50%) Glyceryl trinitrate tablets spray Hydrocortisone injection (100 mg) Oxygen Salbutamol (Flumazenil) Table 2. The management of medical emergencies in practice key points Have well-established drills for emergencies so that everyone knows their role Have emergency phone numbers to hand Have an emergency kit that is regularly checked to ensure it is up-to-date Work so as to prevent emergencies as far as possible Always ensure that the patients have their own medication with them, e.g., a glyceryl trinitrate spray for angina, or ensure that it is to hand in the emergency kit Table 3. The management of a patient with collapse of unknown cause Lie the patient flat and raise their legs Maintain the airway and administer oxygen If no pulse is palpable cardiac arrest institute cardiopulmonary resuscitation If a pulse is palpable assume hypoglycemia and treat by oral or intravenous glucose (depending on the level of consciousness) Give 200 mg of hydrocortisone sodium succinate intravenously Get help The patient may feel nauseated, with a cold, clammy skin. There may be visual disturbance together with a feeling of dizziness. The patientõs pulse will be initially rapid and weak and there may be loss of consciousness. The pulse becomes slow on recovery. Before the patient loses consciousness, the possibility of hypoglycemia should be borne in mind and a glucose drink may be helpful. The patient should be laid flat, so that the legs are higher than the head (heart) and any tight clothing around the neck should be loosened. Recovery is usually rapid and occasionally the patient may jerk as they regain consciousness in a manner resembling a fit. Prolonged unconsciousness should lead to consideration of other causes for the collapse. The diabetic patient A thorough history should always be obtained from a diabetic patient. This should involve an assessment of the degree of diabetic control achieved by the patient. A history of recurrent hypoglycemic episodes and markedly varying blood glucose levels means that a patient attending for dental treatment is much more likely to develop hypoglycemia. It is wise to treat diabetic patients first on the operating list and ensure that they have had their normal antidiabetic medication and something to eat before attending the surgery. Hypoglycemia is much more likely to be encountered in dental practice than hyperglycemia because the former has a more rapid onset. Principally seen in diabetics, it may be seen in very anxious patients who have starved themselves for whatever reason before attending for dental treatment. Diabetic control may be adversely affected by oral sepsis, leading to an increased risk of complications (15). Diabetic emergencies If hypoglycemia occurs, glucose should be given by mouth as tablets, syrup, or a sugary drink, if the patient can cooperate (8). For those patients who are not able to cooperate, glucose is also available as an oral gel in a dispenser (GlucoGel Ò ). If these measures are impossible or ineffective, for example in an uncooperative, semi-conscious or comatose patient, the usual treatment of first choice is glucagon (1 mg ml injection) 1 mg by intramuscular or subcutaneous injection (26). Patients who do not respond to glucagon, or those who have been hypoglycemic for some time and may have exhausted their supplies of liver glycogen, will require up to 50 ml of intravenous glucose solution. Clearly, patients who have reached this stage should be 28

3 Medical emergencies in the dental practice managed under medical supervision and are unlikely to be seen in dental practice. There may be uncharacteristic aggression, drowsiness and a moist skin. Pulse may be rapid and full and blood sugar will be low. The patient should be laid flat if consciousness is lost. If the patient is conscious, then oral glucose (i.e., four lumps of sugar) should be given. If the patient is unconscious then ml glucose should be given intravenously or 1 mg glucagon intramuscularly. Glucagon is more easily administered than intravenous glucose. Medical help should be sought. The mainstay of treatment of hyperglycemia is intravenous rehydration requiring medical intervention and is beyond the scope of this discussion. The management of diabetic patients undergoing surgery In well-controlled diabetics requiring local anesthesia, all that is required is to ensure that these patients are treated promptly, which usually means placing them first on an operating list. They should also have had their normal diet and diabetic medication. becomes more complicated when the patients have to be fasted (28) and outlines of management for patients with type 1 and type 2 diabetes are given in Tables 4 and 5, respectively. It is important that such patients are managed in conjunction with the physician with responsibility for overall diabetic management. It should be remembered that the associated illness will increase basal insulin needs. Hypersensitivity reactions Anaphylaxis Table 4. Preoperative management in type 1 diabetes mellitus fasted patient The patient should be first on the list of patients All long-acting insulin should be stopped the night before surgery Intravenous access should be obtained at an early stage If surgery is in the morning, all subcutaneous morning insulin should be stopped If surgery is in the afternoon, the usual short-acting insulin should be given in the morning at breakfast but no medium or long-acting insulin The urea and electrolytes should be checked on the morning of surgery and an intravenous infusion of 1 litre of 5% dextrose with 20 mmol potassium chloride over 8 hours should continue until the patient is eating normally. Dextrose may need constant infusion to maintain the blood glucose 50 units of short-acting insulin should be added to 50 ml 0.9% saline, which can be given by an infusion pump, and is given according to a sliding scale that can be adjusted dependent on the blood glucose measurements The blood glucose measurements should be checked hourly aiming at a level of 7 11 mmol l Postoperatively the intravenous insulin and dextrose, potassium chloride and sliding scale should be continued until the patient is eating Finger-prick glucose should be checked every 2 hours Table 5. Preoperative management in type 2 diabetes mellitus fasted patient These patients may be managed by attention to diet or, more commonly, use of oral hypoglycemics. A fasting blood glucose of >10 mmol l may require management along the lines of a type 1 diabetic Patients taking a long-acting sulfonylurea should have the dose halved the day before surgery and the tablet should be omitted altogether on the day of surgery. The fasting blood glucose level should be checked on the morning of surgery and treatment is only needed if the level is more than 15 mmol. The blood glucose level should be monitored in any event using a finger-prick blood sample If the blood glucose level is more than 15 mmol, insulin should be used as described in Table 4 Anaphylaxis is a severe allergic reaction. It is a type I hypersensitivity reaction. Other examples of type I reactions include asthma and hay fever. In anaphylaxis, free antigen binds to immunoglobulin E, which is fixed on mast cells and basophils; this leads to the release of vasoactive peptides and histamine. In dentistry, the most common cause is likely to be penicillin or latex but non-steroidal anti-inflammatory drugs can also cause it. Rarely, local anesthetics may be responsible (33). There may be facial flushing, pallor, cyanosis or edema. The skin may be cold and clammy and there 29

4 Greenwood may be urticaria (an itchy rash). Wheezing or laryngospasm and tachycardia and hypotension may also occur. The patient should be laid flat and 0.5 ml of 1:1,000 epinephrine (adrenaline) should be administered intramuscularly. Epinephrine administration should be repeated at 10-minute intervals as necessary. The epinephrine has both a and b effects; it reverses peripheral vasodilatation and reduces edema. The b-activity dilates the airway and increases the force of myocardial contraction. It also suppresses histamine and leukotriene release. Adverse effects from epinephrine are rare when appropriate doses are given intramuscularly. A clear airway should be ensured and 100% oxygen should be administered. Ten to 20 mg chlorphenamine (antihistamine) should be given intravenously plus 100 mg of intravenous hydrocortisone sodium succinate, which helps to reduce edema and stabilizes the mast cells. An inhaled b 2 -agonist can be useful to facilitate bronchodilation. The patient should be admitted to hospital because there may be a rebound attack. Chlorphenamine and hydrocortisone need not be given by non-medical first-responders (2). The Resuscitation Council (UK) does not define specifically the position of dentistry but if the practitioner is confident in drug administration it will do no harm to administer these drugs. Whatever the status of the resuscitator, epinephrine must be given and the preferred injection site is shown in Fig. 1. Many patients with a history of anaphylactic reactions will carry an ÔEpipenÕ, which contains 300 lg epinephrine (Fig. 2). Fig. 2. An Epipen. Angioedema Angioedema is triggered when mast cells release histamine and other chemicals (essentially vasoactive peptides) into the blood, producing rapid swelling. From a medical perspective, angioedema is lifethreatening if the swelling produced compromises the airway. It may be precipitated by substances such as latex and drugs including penicillin, non-steroidal anti-inflammatory drugs and angiotensin-converting enzyme inhibitors (e.g., captopril and lisinopril). There is a hereditary component to angioedema. Swelling of the skin occurs, especially around the eyes and lips but also in the throat and on the extremities. Laryngeal edema and bronchospasm lead to the same clinical situation as anaphylaxis. In cases of severe angioedema, patients may be prescribed prednisolone. Acute allergic edema of this type can develop alone or it may be associated with anaphylactic reactions. Hereditary angioedema is caused by continued complement activation resulting from a deficiency of the inhibitor of the enzyme C1 esterase. The inheritance is usually autosomal dominant and may not present until adult life. C1 esterase inhibitor concentrates are available to supplement the deficiency. Such supplements should be administered before dental treatment if such treatment has, in the past, triggered the onset of angioedema. Fits Fig. 1. The preferred site for epinephrine injection. It is important that the practitioner is aware if a patient has epilepsy; hence the importance of a thorough history (36). The nature of the seizures, their frequency, and the degree of control, including the type of medication used, are important factors to be elicited. 30

5 Medical emergencies in the dental practice The signs and symptoms of fits vary widely depending on the underlying cause. An obvious fit is easily recognized. In most cases the main aim of management is to prevent the patient from injuring themselves during the fit. If a fit has stopped and the patient is in the immediate aftermath (Ôpost-ictal phaseõ) they should be placed in the recovery position. If the convulsions are ongoing, mg diazepam should be given intravenously, slowly. The possibility of the patientõs airway becoming occluded should be constantly remembered and the airway must therefore be protected. It may be appropriate to abort dental treatment if a patient experiences a fit during treatment. Chest pain Table 6. The main causes of chest pain Angina Myocardial infarction Pleuritic, e.g., pulmonary embolism Musculoskeletal Esophageal reflux Hyperventilation Most patients who are likely to suffer chest pain of cardiac origin in the dental environment are likely to have a previous history of cardiac disease. Again, the history is important as well as recognizing risk factors for cardiovascular disease, which include smoking, excess alcohol, diabetes mellitus, hypertension, hypercholesterolemia, a family history of cardiovascular disease, sedentary lifestyle and obesity. In addition, symptomatic cardiovascular disease is more common with increasing age. It is important that if a patient uses medication to control angina it should be with them or be readily to hand in the emergency kit in case the patient needs it. Likewise, it is important that the patient has taken their normal medication. Features which make the pain unlikely to be cardiac in origin are: pains lasting less than 30 seconds however severe, stabbing pains, well-localized left submammary pain and pains that continually vary in location. A chest pain that is improved by stopping exercise is more likely to be cardiac in origin than one that is not exercise-related. Pleuritic pain is sharp and made worse on inspiration, for example following pulmonary embolism. Oesophagitis may cause a retrosternal pain. This will be worse on bending or lying down. However, oesophageal pain, like cardiac pain, can be relieved by sublingual nitrates, for example glyceryl trinitrate. Hyperventilation may produce chest pain and both gall bladder and pancreatic disease can mimic cardiac pain. Musculoskeletal pain is often accompanied by tenderness to palpation in the affected region. A summary of the main possible causes of chest pain is given in Table 6. Clearly important conditions to exclude when a patient complains of chest pain are angina and myocardial infarction (3, 17, 44). The pain of angina and myocardial infarction may be very similar comprising a crushing central chest pain (like a tight band around the chest) radiating to the left arm (usually) or mandible. Angina is usually relieved by the patientõs medication, which in most cases will be a glyceryl trinitrate spray. The pain of angina usually lasts for less than 3 minutes if glyceryl trinitrate is used. Myocardial infarction is often accompanied by other symptoms, such as sweating, nausea and palpitations, and is not relieved by glyceryl trinitrate. There may be breathlessness and vomiting and the patient may lose consciousness. A calm and reassuring manner from the practitioner is important. If the patient has a history of angina get the patient to use the normal medication there should be a rapid response (within a few minutes) if the cause was angina. Glyceryl trinitrate should be part of the emergency drug box in case patients do not have their own medication with them. If a myocardial infarction is suspected, help should be summoned at an early stage and 300 mg aspirin should be administered to be chewed (if not contraindicated). The patient will be most comfortable in a sitting position. Ensure that the airway is maintained and administer a mix of nitrous oxide and oxygen, which has analgesic and anxiolytic effects. A patient who has had a myocardial infarction attending hospital may be given one of the so-called Ôclot bustingõ agents, such as streptokinase. There 31

6 Greenwood are strict criteria detailing in which patients this medication should be used because widespread bleeding can result. As a consequence of this, a patient who had undergone recent surgery would be excluded. More recent management advances include immediate angioplasty, where facilities and expertise allow. Cardiac arrest The risk factors for developing cardiovascular disease were given earlier. In addition, it should be remembered that chronic respiratory disorders can lead to cardiac failure, so-called cor pulmonale. In addition, a more acute respiratory problem may cause respiratory arrest, which then proceeds to cardiac arrest. Possible causes of cardiac arrest include: myocardial infarction, choking, bleeding, drug overdose, and hypoxia. UNRESPONSIVE? Shout for help Open Airway NOT BREATHING NORMALLY? Call 999 (UK)/911 (USA) 30 Chest Compressions The patient loses consciousness and there is no respiration or pulse. Basic life support implies that no equipment is employed other than a protective device. It has been suggested (31), that cardiopulmonary resuscitation can be performed effectively in the dental chair but it is important that this is confirmed locally. The Guidelines issued by the Resuscitation Council (UK) with regard to adult basic life support changed in April 2006 (2). There are two underlying main themes first the need to increase the number of chest compressions given to a victim of cardiac arrest and second, the importance of keeping the guidelines simple. Interruptions to chest compression in resuscitation are common (20) and are associated with a reduced chance of survival (25). The ideal situation is to be able to deliver continuous chest compressions while giving ventilations independently. This is only possible, however, when an advanced airway is placed. Chest-compression-only cardiopulmonary resuscitation is another way to increase the number of compressions but is only effective for a period of about 5 minutes (25). For this reason this technique is not recommended as standard management. The principle on which compression-only cardiopulmonary resuscitation works is that during the first few 2 rescue breaths 30 compressions Fig. 3. Algorithm for Adult Basic Life Support; from Resuscitation Guidelines 2005 Resuscitation Council (UK). minutes after a non-asphyxial cardiac arrest the blood oxygen content remains high and therefore at this stage ventilation is less important than chest compression. Rescuers are now taught to place the heel of their hand in the center of the chest (sternum) with the other hand on top and this is demonstrated by placing the hands in the middle of the lower half of the sternum. The chest should be compressed at a rate of about 100 per minute. The basic algorithm for adult basic life support is given in Fig. 3. In Guidelines published in 2000 the concept of checking for Ôsigns of a circulationõ was introduced. Changes were made in 2005 because it had been found that checking the carotid pulse to diagnose cardiac arrest can be unreliable, even sometimes when attempted by some health-care professionals (6). In Guidelines 2005 the absence of breathing is the main sign of cardiac arrest (2). Also highlighted is the need to identify agonal gasps (as well as the absence of breathing) as a sign to commence cardiopulmonary resuscitation. In the new guidelines, it is still stressed that before resuscitation attempts are made, it should be ensured that the environment is safe before proceeding. 32

7 Medical emergencies in the dental practice Unresponsive Call for help Open airway Not breathing normally CPR 30:2 Until Automated External Defibrillator is attached Send or go for Automated External Defibrillator Call 999 (UK) 911 (USA) Automated External Defibrillator assesses Shock advised No shock advised 1 shock J biphasic or 360 J monophasic Immediately resume CPR 30:2 for 2 min Immediately resume CPR 30:2 for 2 min Continue until the victim starts to breathe normally Fig. 4. Algorithm for the use of an automated external defibrillator in cardiac arrest. Use of defibrillation Ventricular fibrillation is the most common cause of cardiac arrest. It is a rapid and chaotic rhythm. As a result, the heart is unable to contract and therefore unable to sustain its function as a pump. Defibrillation is the term that refers to the termination of fibrillation. It is achieved by administering a controlled electrical shock to the heart; this may restore an organized rhythm enabling the heart to contract effectively. It is now well recognized that early defibrillation is important. The only effective treatment for ventricular fibrillation is defibrillation and the sooner the shock is given, the greater the chance of survival (30, 39). The provision of defibrillation has been made easier by the development of automated external defibrillators. These are sophisticated, reliable, safe, computerized devices that use voice and visual prompts to guide rescuers and are suitable for use by lay people and health-care professionals (13). The devices analyse the victimõs rhythm, determine the need for a shock and then deliver a shock. The automated external defibrillator algorithm is given in Fig. 4. Placement of automated external defibrillator pads The victimõs chest must be sufficiently exposed. Chest hair will stop the pads adhering properly and if 33

8 Greenwood The patient will be breathless with an expiratory wheeze and may be using the accessory muscles of respiration. The patient will usually be tachycardic. Fig. 5. Carpo-pedal spasm. excessive it must be rapidly removed if possible. Resuscitation should never be delayed for this reason, however. One pad should be placed to the right of the sternum below the clavicle. The other pad should be placed in the mid-axillary line, approximately level with the V6 electrocardiogram electrode position. This position should be clear of any breast tissue. Although most automated external defibrillator pads are labeled, or carry a picture of their position, it does not matter if they are reversed. A calm and reassuring presence by the practitioner is important. The patient will be most comfortable in a sitting position and should use his her normal asthma medication. Oxygen should be administered and also hydrocortisone sodium succinate (200 mg) should be administered intravenously this will reduce edema. If the attack has not responded rapidly using only the patientõs usual medication, then the patient should be admitted to hospital. It may improve delivery of the patientõs own inhaler contents if a spacer device is used. The method described in the British National Formulary (14) is to apply the mouthpiece of the inhaler to the underside of a paper cup through which a hole has been cut. If the open end of the cup is placed against the mouth and nose, aerosol delivery should be improved. Asthma Asthma is a potentially life-threatening condition that should always be taken seriously (35). Exertion, anxiety, infection, or exposure to an allergen may all precipitate an attack. Bronchial asthma results from bronchial hyper-reactivity, which leads to expiratory wheezing, dyspnea, and cough. Asthma is paroxysmal and sufferers may therefore be completely normal between attacks. Again, it is important to get an idea of the severity of the condition, which will usually come from the history. Important facts to ascertain are the effectiveness of medication, precipitating factors, hospital admissions as the result of asthma and the use of systemic steroids. It is important that asthmatic patients bring their usual inhalers medication with them to dental appointments. If the inhaler has not been brought, it must be in the emergency kit or treatment should be deferred. If the asthma is in a particularly severe phase, elective treatment may be best postponed. The drugs that may be prescribed by dental practitioners, particularly non-steroidal anti-inflammatory drugs, may worsen asthma and are therefore best avoided. Hyperventilation Hyperventilation is a more common emergency than is often thought. When hyperventilation itself persists it is extremely distressing to the patient. Anxiety is the principal precipitating factor. The patient may feel weak and light-headed or dizzy and may complain of paresthesia, for example in the hands, or may complain of muscle pain. The patient may have palpitations and chest pain; indeed patients are sometimes convinced that they are having a myocardial infarction. Carpo-pedal spasm may occur if hyperventilation is prolonged (Fig. 5). Clearly a calm and sympathetic approach by the practitioner is important. The diagnosis is not always as obvious as it may seem. When other causes for the symptoms have been excluded patients should be encouraged to rebreathe their own exhaled air so as to increase the amount of 34

9 Medical emergencies in the dental practice Unconscious Start CPR carbon dioxide being inhaled. Hyperventilation leads to carbon dioxide being Ôwashed outõ of the body, so producing an alkalosis. Rebreathing exhaled air returns the situation to normal. This is achieved by breathing in and out of a paper bag applied over the mouth and nose. Choking Severe airway obstruction (Ineffective Cough) Assess Severity Conscious 5 back blows 5 abdominal thrusts Mild airway obstruction (Effective Cough) Encourage Cough Continue to check for deterioration to ineffective cough or relief of obstruction Fig. 6. Algorithm for management of choking; from Resuscitation Guidelines 2005 Resuscitation Council (UK). Table 7. of a choking victim; adapted from Resuscitation Guidelines 2005 Resuscitation Council UK General signs of choking Attack occurs while eating misplaced dental instrument restoration Victim may clutch his neck Signs of mild airway obstruction Response to question ÔAre you choking?õ Victim speaks and answers ÔYES!Õ Other signs Victim is able to speak, cough and breathe Signs of severe airway obstruction Response to question ÔAre you choking?õ Victim unable to speak Victim may respond by nodding Other signs Victim unable to breathe Breathing sounds wheezy Attempts at coughing are silent Victim may be unconscious A foreign body may lead to either mild or severe airway obstruction. that aid in differentiation are shown in Table 7, which is taken from the Resuscitation Council UK Guidelines 2005 (2). In the conscious victim it is useful to ask the question ÔAre you choking?õ. An algorithm for the management of a choking patient has been published by the Resuscitation Council (UK) (2). This is shown in Fig. 6. The back blows shown in the algorithm are given by standing to the side of the victim and slightly behind. The chest should be supported with one hand and the victim leant well forwards so that when the obstruction is dislodged it is expelled from the mouth rather than passing further down the airway. Up to five sharp blows should be given between the shoulder blades with the heel of the other hand. After each back blow a check should be made to see if the obstruction has been relieved. If the back blows fail to relieve the obstruction, up to five abdominal thrusts should be given. The method being as follows: stand behind the victim and put both arms around the upper part of their abdomen and lean the victim forwards. The rescuerõs fist should be clenched and placed between the umbilicus and lower end of the sternum. This clenched fist should be grasped with the other hand and pulled sharply inwards and upwards; this should be repeated up to five times. If the obstruction is not relieved then an alternating pattern of five back blows with five abdominal thrusts should be used. If it is suspected that a foreign body has been inhaled in the context of dental practice, the patient must be referred for chest X-ray. Radiographs will be taken in two planes (postero-anterior and lateral). The foreign body is most likely to be seen in the right lung because the right main bronchus is more vertical than the left. Bronchoscopy or even thoracotomy may be required to retrieve the foreign body. Adrenal crisis Adrenal crisis may result from adrenocortical hypofunction leading to hypotension, shock, and death. It may be precipitated by stress induced by trauma, surgery, or infection. Adrenocortical hypofunction can be primary or secondary. An example of primary hypoadrenocorticism is AddisonÕs disease, in which there are circulating autoantibodies to the adrenal cortex. This results in atrophy and failure 35

10 Greenwood of secretion of hydrocortisone and aldosterone. Tuberculous destruction of the adrenal glands will produce the same effect. Secondary hypoadrenocorticism results from adrenocortical hypofunction as the result of adrenocorticotrophic hormone deficiency. This occurs through suppression of adrenocortical function following the use of systemic corticosteroids. The use of supplemental steroids before dental surgery in patients at risk of an adrenal crisis is a contentious issue. The rationale for steroid supplementation is as follows. A normal physiological response to trauma is to increase corticosteroid production in response to stress. If this response is absent, hypotension, collapse, and death will occur. The hypothalamo pituitary adrenal axis will fail to function if either the pituitary or the adrenal cortex ceases to function for the reasons mentioned above. This happens in secondary hypoadrenocorticism because administration of corticosteroids leads to negative feedback to the hypothalamus, causing decreased adrenocorticotrophic hormone production and adrenocortical atrophy. This atrophy means that an endogenous steroid boost cannot be produced in response to stress. Recent studies have suggested that dental surgery may not require supplementation (38). More invasive procedures however, such as third molar surgery or the treatment of very apprehensive patients, may still require cover. It is wise, even if supplementary steroids have not been used, to monitor the blood pressure of patients taking steroids. If the diastolic pressure falls by more than 25%, then an intravenous steroid injection (100 mg hydrocortisone) is indicated. Patients who may require supplementation are those who are currently taking corticosteroids or have done so in the last month. A supplement may also be required if steroid therapy has been used for more than 1 month in the previous year. If the patient is receiving the equivalent of 20 mg prednisolone daily then extra supplementation is not required. The patient loses consciousness and has a rapid, weak, or impalpable pulse. The blood pressure falls rapidly. The patient should be laid flat and 200 mg (at least) hydrocortisone sodium succinate should be administered intravenously. Ensure a clear airway and administer oxygen. Then call an ambulance or telephone the hospital emergency number. Stroke Strokes can be either hemorrhagic or embolic in etiology but clinically the effects are essentially the same. Risk factors for stroke include hypertension, smoking, diabetes mellitus, cardiac and peripheral vascular disease, atrial fibrillation, obesity, hyperlipidemia and excess alcohol intake. Previous transient ischemic attacks (focal central nervous system disturbances caused by vascular events such as microemboli and occlusion leading to ischaemia) are also risk factors. By definition, symptoms of transient ischaemic attacks last for less than 24 hours. These vary according to the site of brain damage. There may be loss of consciousness and weakness of the limbs on one side of the body. The side of the face may be weak, indicating an upper motor neuron lesion, in which case the forehead will not be affected on that side. The airway should be maintained and an ambulance called. Local anesthetic emergencies Allergy to local anesthetic is rare but should be managed as for any other case of anaphylaxis. When taken in the context of the number of local anesthetics administered, complication rates are low, but complications can occur (29, 33). The signs and symptoms are those of anaphylaxis. Other local anesthetic reactions are rare. Fainting in association with the injection of local anesthetic is rather more common and can usually be avoided by administering the local anesthetic while the patient is supine. Intravascular injection of local anesthetic can be avoided by the use of an aspirating syringe. An intravascular injection can induce agitation, drowsiness, or confusion with fits and ultimately loss of consciousness. Other causes of local anesthetic-related problems are given in Table 8. 36

11 Medical emergencies in the dental practice Table 8. Potential problems with local analgesia Local anesthetic allergy Cardiovascular reactions Palpitations Myocardial infarction Hypotension Hypertension Facial palsy or diplopia of an intravascular local anesthetic injection Stop local anesthetic injection Lay the patient flat with legs raised Maintain the airway Reassure the patient that they should recover within 30 minutes Cardiovascular problems in association with local anesthetics The most common symptoms to be precipitated are palpitations, which will subside naturally with time. A myocardial infarction may rarely be precipitated in a susceptible patient. It is possible for interaction with antihypertensive drugs to precipitate hypotension. It is important in these circumstances to ensure that the airway remains clear and that the patient is reassured. Medical assistance should be sought. Hypertension should likewise be managed with medical assistance. In any circumstance in which a cardiovascular event is precipitated, treatment should be deferred for another occasion. Temporary facial palsy or diplopia Complications such as these arise from the local anesthetic agent tracking towards the facial nerve or the orbital contents. The patient should be reassured because the effects wear off as the effects of the local anesthetic diminish. If the temporal and zygomatic branches of the facial nerve are involved, it is important to protect the cornea and an eye patch is indicated as a temporary measure. Needle breakage The incidence of needle breakage has decreased since the advent of single-use needles; however, it is still a recognized complication. The breakage of a needle has most commonly been seen in relation to the inferior alveolar nerve block. The incidence of this Table 9. of a broken needle in a dental patient If tip is visible Remove with artery forceps If tip is not visible Inform the patient Arrange immediate maxillofacial referral Advise the patient against moving the mandible as much as possible Ensure accurate records and inform Protection Societies complication was more common in the 1950s and before (12). Needle breakages often occur at the hub of the needle and are more common with needles of smaller diameter. If this event does occur the needle should be retrieved immediately, if possible, using fine artery forceps. This is only possible if the needle is not inserted to the hilt while the injection is given and for this reason the needle should not be inserted to this degree on any occasion. If immediate retrieval is not possible the patient should be informed about what has happened and referred immediately to the local maxillofacial unit (Table 9). It is important for medico-legal reasons that the incident is accurately and clearly documented. The practitionerõs dental or medical Protection Societies should also be informed of such an incident. It is useful if the remaining part of the needle is sent along with the patient because it will allow better estimation of the size of the retained fragment. Although imaging will be carried out at the hospital, first by plain radiography (two views at right angles) and then by computed tomography scanning, the size remaining is still best judged from the fragment left attached to the syringe. It is important that the needle is retrieved promptly because there is the potential for pain, trismus, and dysphagia to develop. There is also the possibility of migration of the needle. It can be difficult, despite good imaging, to locate the needle and there is a school of thought that, because the needle is sterile, if there is no reason to suspect migration, the needle should be left in situ unless complications develop (21). Sedation emergencies These are usually avoidable by careful technique, but may relate to overdose or hypoxia or both. Either of 37

12 Greenwood these situations can lead to a respiratory arrest if not addressed and the patient will be obviously cyanosed (33). During any dental treatment, the vital signs should be observed (22) but this is particularly important during sedation when they should be formally monitored. No further sedation agent should be given. Open and maintain the airway and give oxygen; ventilate the patient. If an overdose is suspected consider the use of flumazenil. Emergencies arising from impaired hemostasis It is important that any potential problems with hemostasis are uncovered in the medical history and therefore can be anticipated and prevented. Despite this, however, hemorrhage may occur postoperatively in dental patients and may be classified into Primary, which is bleeding at the time of surgery, and Reactionary, which is bleeding a few hours after surgery. Reactionary hemorrhage is often attributable to the effects of a vasoconstrictor-containing local anesthetic wearing off. Secondary hemorrhage is that which occurs a few days after the operative procedure and is usually attributable to infection. No surgical procedure should be performed on a patient with a bleeding disorder without consultation with the patientõs physician or hematologist. Patients with congenital bleeding disorders should be treated in specialist centers that facilitate communication between surgeon and hematologist. Patients with hemophilia A, Christmas disease, or von WillebrandÕs disease may require replacement therapy before surgery and an antifibrinolytic agent postoperatively (e.g., tranexamic acid). The use of local measures, such as suturing and packing with a hemostatic agent, for example oxidized cellulose (Surgicel Ò )or collagen sponge (Haemocollagen Ò ), both of which are resorbable, should be considered (11). Bone wax is a useful method of arresting persistent bony oozing. The minimum amount of bone wax possible should be used because of the risk of development of a foreign body granuloma. There have been changes in recent years to the management of patients taking drugs that interfere with hemostasis. It is unusual in contemporary practice to withdraw aspirin before surgery, for example. If aspirin did need to be withdrawn then this should be done 10 days before surgery because the effect on platelets is irreversible and time is needed to allow some replacement of the platelet population. If aspirin is continued, local hemostatic measures are usually sufficient. Likewise, other antiplatelet drugs, such as clopidogrel and dipyridamole, do not need to be stopped before surgery, local hemostatic measures being adequate. Data from the literature do not support the assumption, widely held in the past, that there was no significant risk to a patient if warfarin therapy was stopped to facilitate surgical dental treatment (41). A review of over 500 reports, in which anticoagulation was stopped before a variety of dental procedures, reported the following: the majority of patients had no adverse effects but four patients experienced fatal thromboembolic events and one patient experienced embolism which was non-fatal (40, 41). It cannot be proved conclusively that the withdrawal of anticoagulant was responsible but it would appear logical. Reports from the literature have also suggested that stopping warfarin treatment may lead to a hypercoagulable state as the result of a rebound phenomenon (41, 42). The existence of a hypercoaguable state has not been fully elucidated. Patients on warfarin therapy should have their International Normalized Ratio (INR a measure of the prothrombin time) measured before any surgical procedure. This can now be performed in the dental surgery using a finger-prick sample. The normal therapeutic international normalized ratio for warfarinized patients is 2 3, except for those with cardiac valve replacements in whom the range is There does not appear to be a universally acknowledged satisfactory international normalized ratio for dental surgery. In the United Kingdom, current advice (14) is that most surgical procedures in dentistry, such as extractions and simple minor oral surgical procedures, may be carried out if the international normalized ratio is <3.0 without alteration of the warfarin dosage. In practice, up to 4 is probably safe. If the international normalized ratio is >3, referral to the supervising physician is needed. If possible, even if the international normalized ratio is <3 it is advisable to avoid regional block anesthesia, but not essential. Avoidance may be achieved by the use of intraligamentary injections. In all warfarinized patients local measures for hemostasis must be employed. It is important that patients with an international normalized ratio >3 do not undergo any form of 38

13 Medical emergencies in the dental practice Table 10. Systemic conditions leading to a potential deficiency in hemostasis Liver impairment and or alcoholism Renal failure Patients receiving cytotoxic medication or radiotherapy Thrombocytopenia, hemophilia, or other known disorders of hemostasis surgical procedure without consultation with the physician who is coordinating the anticoagulation. In addition, patients taking warfarin who have concurrent medical problems, listed in Table 10 should not be treated without medical consultation (32). Occasionally, patients receiving heparin therapy may be encountered. The most common group is patients who are heparinized to facilitate hemodialysis for renal failure. The heparinization is often carried out about three times per week, but because of the short half-life of heparin (around 5 hours) treatment can be carried out safely on the days between dialysis treatments. If a heparinized patient requires emergency treatment, such as an extraction, then the effects of heparin can be reversed by the antagonist protamine sulfate (10 mg ml). Tranexamic acid is an antifibrinolytic agent whose primary action is to block the binding of plasminogen and plasmin to fibrin, thereby preventing fibrinolysis (37). There is limited published evidence, but has been suggested that, compared with no local measures, tranexamic acid mouthwash as a 4.8% preparation reduces postoperative bleeding in anticoagulated patients (37). Problems with medication and hemostasis Some drugs that are commonly used in dental practice interact with anticoagulants. Examples of analgesics that do this are aspirin, diclofenac, diflunisal, ibuprofen, and long-term use of paracetamol; all of these increase the effect of warfarin. Antimicrobials, such as those of the penicillin group, can increase the prothrombin time in warfarinized patients but this is uncommon. Erythromycin enhances the anticoagulant effect of warfarin and nicoumalone by reducing the metabolism of the latter drugs. The combined use of these drugs is not absolutely contraindicated but monitoring of the patients is required. The interaction between warfarin and metronidazole is clinically important because the antibiotic inhibits the metabolism of the anticoagulant (27). Tetracycline may enhance the effect of warfarin and the other coumarin anticoagulants. Miconazole can enhance the effects of warfarin even after topical use and it can lead to catastrophic bleeding. One case has been reported in which a patientõs international normalized ratio increased from 2.5 to 17.9 following the use of miconazole oral gel (19). In distinction to the above drugs, carbamazepine may reduce the effect of warfarin because the metabolism of the anticoagulant is increased. Further details of drug interactions with warfarin are discussed elsewhere in this volume. Patients who have liver failure can be difficult to evaluate with regard to the risk of oral bleeding postsurgically (32). A relatively small elevation of the prothrombin time suggests significant liver damage. There are various methods of improving the haemostatic picture, for example the intravenous injection of vitamin K, but this should be carried out by the hematologist. Fresh frozen plasma will lower the prothrombin time and platelet transfusion addresses both quantitative and qualitative problems. In patients with hepatic problems, care should be exercised in the use of opioid analgesics, for example morphine, and sedatives such as diazepam. Smaller doses should be used for drugs that are metabolized by the liver. The use of paracetamol should be avoided in the presence of liver failure and alcoholism (32). Acute pain management Pain results from damage to tissue that induces the release of chemicals, which include prostaglandins, serotonin, bradykinin, thromboxane, leukotrienes, and substance P. It is also a highly subjective phenomenon. Practitioners may find themselves in the situation where a patient is in acute pain and the subjective nature of pain is such that the same condition in one patient may effectively produce more pain than the same condition produces in another. Wherever possible, attention should be given to treating the underlying cause of pain. Analgesics may either act peripherally or centrally. The former acts at the site of injury whereas the latter attempts to change the cerebral perception of pain. The decision with regard to which analgesic should be used is made with reference to the Ôladder of analgesiaõ (Fig. 7). 39

14 Greenwood Severe pain - paracetamol and injected opioid e.g. morphine Moderate pain - paracetamol with or without an oral opioid or non-steroidal Mild pain - paracetamol Fig. 7. The ladder of analgesia. Control of mild pain The drug of first choice is paracetamol, which acts peripherally. It has no anti-inflammatory activity. It is a very useful agent for reducing the temperature in a pyrexial patient. As long as the correct dose schedule is adhered to, the drug is safe and does not cause gastric irritation. Non-steroidal anti-inflammatory drugs block cyclo-oxygenase and can therefore interfere with hemostasis and cause gastric irritation. Like paracetamol, non-steroidal anti-inflammatory drugs act peripherally. As a result of gastric irritation, particularly in the elderly and those taking corticosteroids, caution should be exercised. Some practitioners would prescribe them in conjunction with a proton pump inhibitor or H2 antagonists in such patients. The elderly are also at risk from acute renal failure because non-steroidal anti-inflammatory drugs block renal prostaglandin synthesis. Other groups at risk of renal failure with non-steroidal anti-inflammatory drugs are those with cardiac failure and pre-existing renal damage such as diabetic nephropathy. The original non-steroidal anti-inflammatory drug is aspirin, which irreversibly inhibits platelet function and increases the bleeding time. Platelet repopulation is required for the effects to be reversed. In most cases aspirin is continued and local haemostatic measures are employed if surgery is undertaken. It should be remembered that non-steroidal antiinflammatory drugs can induce asthma in susceptible patients and they should therefore be avoided in this group of individuals. Control of moderate pain One of the weak oral opioids, such as codeine, is a good analgesic that acts centrally. The opioids are contraindicated in patients who have significant acute or chronic respiratory disease or who have been taking monoamine oxidase inhibitors within the last 14 days. The potential problem with patients who have a respiratory problem is that respiratory depression may be clinically significant. Codeine compound products are now available, such as co-codamol which is a codeine paracetamol preparation. It contains codeine phosphate 8 mg and paracetamol 500 mg. It is important that if a practitioner prescribes this medication, the patient is informed that they must not take it in conjunction with paracetamol because overdose could easily occur. Control of severe pain Attention should be given to addressing the underlying cause. Despite this, however, the dental practitioner will sometimes be faced with a situation requiring the most effective analgesia. Morphine and pethidine by injection (either intramuscular or intravenous) can be used but analgesia at this level is usually restricted to inpatient use, often with medical consultation. As both of these analgesics can cause respiratory depression, supplemental oxygen may be indicated. One acute presentation of pain to the dental practitioner can be related to temporomandibular joint pain dysfunction syndrome. Muscle spasm often seem to be the main source of pain, which can be treated empirically using a soft lower splint fitted over the occlusal surfaces of the mandibular teeth. Diazepam can be prescribed on a short-term basis during an acute phase because it has muscle relaxant qualities in addition to its anxiolytic properties. It is important to distinguish the temporomandibular joint pain described above from neuropathic pain, which occurs as a result of damage to neural tissue. Summary Medical emergencies occurring in dental practice can be alarming. The keys to minimizing alarm are taking a thorough history so that possible emergencies can be, to some extent, anticipated, and having a good working knowledge of how to manage emergencies, should they arise. References 1. ADA Council on Scientific Affairs. Office emergencies and emergency kits. J Am Dent Assoc 2002: 133: Adult Basic Life Support Resuscitation Guidelines. London: Resuscitation Council (UK), Assael LA. Acute cardiac care in dental practice. Dent Clin North Am 1995: 39: Atherton GJ, McCaul JA, Williams SA. Medical emergencies in general dental practice in Great Britain. Part 3: percep- 40