Local anaesthetics Continued »


bypass graft surgery within three months warrant all elective dental treatment to be deferred47


. If emergency treatment is


imperative, stress-reduction protocols with antianxiety agents are advisable with a limitation of two cartridges of adrenaline containing anaesthetic48


. As part of a stress reduction protocol,


the Wand allows the dentist to administer local anaesthetic with a non-threatening handpiece. The anaesthetic syringe is often the principle cause of stress for patients as it is considered by many as the most uncomfortable part of dental treatment. The Wand helps deliver a computer- regulated flow of anaesthetic that enables pain-free dental anaesthesia for the different types of injections. This can help to make the patient less anxious.


CARDIAC DYSRHYTHMIA Elective dentistry should be postponed in patients with severe or refractory dysrhythmias until they are stabilised. It is safe to limit the local anaesthetic dose to two cartridges of lignospan 2 per cent containing ı:80,000 adrenaline49


.


The use of periodontal ligament or intraosseous injections using an adrenaline-containing local anaesthetic is contraindicated50


.


CONGESTIVE HEART FAILURE Patients taking digitalis glycosides, such as digoxin, should be carefully monitored if adrenaline containing anaesthetics are administered as an interaction between these two drugs can trigger dysrhythmias. Patients taking long-acting nitrate medications or taking a vasodilator medication may show decreased effectiveness of the adrenaline and therefore may experience a shorter duration of dental local anaesthesia48


.


CEREBROVASCULAR ACCIDENT Following a stroke it is recommended that dental treatment be deferred due to the significantly elevated risk of recurrence. Following a six-month interval dental procedures can be re-scheduled with the use of adrenaline-containing local anaesthetics. If the stroke patient has associated cardiovascular problems, the dosage of local anaesthetic with vasoconstrictor should be kept to a minimum48


.


ASTHMA Stress can precipitate an asthma attack


making stress-reduction protocols essential. Conservative use of local anaesthetics containing adrenaline is advised. The Food and Drug Administration warn that drugs containing sulfites can cause allergic reactions in susceptible individuals5ı


. Some studies


suggest that sodium metabisulfite which is an antioxidant agent used in dental local anaesthetic may induce asthma attacks52.


Data is


limited on the incidence of this reaction and even in sulfite-sensitive patients it appears to be an extremely small risk. Indications are that more than 96 percent of asthmatics are not sensitive to sulfites; and those who are sensitive are usually severe, steroid


dependent asthmatics53. Perusse and colleagues concluded


that local anaesthetic with adrenaline can be safely used in patients with nonsteroid-dependent asthma. However, until we learn more about the sulfite sensitivity threshold, consevative use of local anaesthetic with adrenaline in corticosteroid-dependent asthma patients is advisable. This is due to their higher risk of sulfite allergy and the possibility that an unintentional intravascular injection might occur causing a severe asthmatic reaction in a sensitive patient54


. However, in recent


times the results of these older studies have been regarded as questionable by many in the profession.


HEPATIC DISEASE In patients with chronic active hepatitis or with carrier status of the hepatitis antigen local anaesthetic doses must be kept to a minimum. In patients with more advanced cirrhotic disease, metabolism of local anaesthetics may be significantly slowed, resulting in increased plasma levels and complications from toxicity reactions. Local anaesthetic dosage may need to be decreased and the time lapse between injections extended55


.


DIABETES Some patients experience dramatic swings between hyperglycemia and hypoglycemia and, therefore, the use of adrenaline- containing anaesthetics should be reduced due to the risk of adrenaline-enhanced hypoglycemia48


.


COCAINE The major concern in patients abusing cocaine is the significant danger of myocardial ischemia, cardiac dysrhythmias, and hypertension. Some researchers


recommend deferral of dental treatment for 24 to 72 hours56


.


TRICYCLIC ANTIDEPRESSANTS One to two cartridges of adrenaline- containing local anaesthetic can be safely administered to patients taking these drugs. However, careful observation at all times for signs of hypertension is necessary due to enhanced sympathomimetic effects57


.


HIV Protease-inhibitor drugs have been shown to increase the plasma levels of lignospan potentially increasing cardiotoxicity58


.


PARKINSON’S DISEASE Athough there is no data regarding the influence of the anti-Parkinson drug entacapone, caution is advised while using adrenaline-containing anaesthetics. Three cartridges of 2 per cent lignospan with ı:80,000 adrenaline is the recommended upper limit in adults59


.


LOCAL ANAESTHETIC REVERSAL A local anaesthetic reversal agent has been introduced that effectively reverses the influence of adrenaline on submucosal vessels. Phentolamine (Ora Verse) is an alpha receptor blocker formulated in dental cartridges60


. In the future this may prove


useful for some medically compromised patients such as diabetics or elderly patients for whom adequate nutrition may be hindered by prolonged numbness. However, currently this reversal agent is not available in Ireland or in the UK.


REFERENCES Due to issues of space, the full list of reference for this article are available on the Ireland’s Dental magazine website at www.irelandsdental.ie or by emailing bruce@connectcommunications.co.uk


ABOUT THE AUTHOR


Dr Laura Fee graduated with an honours degree in dentistry from Trinity College, Dublin. During her studies, she was awarded the Costello medal for undergraduate research on cross-infection control procedures. She is a member of the Faculty of Dentistry at the Royal College of Surgeons and, in 2013, she completed the Certificate in Implant Dentistry with the Northumberland Institute of Oral Medicine and has since been awarded the Diploma in Implant Dentistry with the Royal College of Surgeons, Edinburgh. Laura is currently completing the Certificate in Minor Oral Surgery with the Royal College of Surgeons, England. She has also been involved with undergraduate teaching in the School of Dentistry, Belfast where she has an honorary oral surgery contract.


Ireland’s Dental magazine 29


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