INTRODUCTION

Anaphylaxis is a life-threatening emergency which can occur in the dental practice (Müller et al., 2008). Anaphylaxis in the dental practice is very rare, accounting for approximately 1% of all encountered emergencies (Müller et al., 2008). It may follow the administration of a drug, e.g. local anaesthetic, or exposure to a substance such as latex (Resuscitation Council (UK), 2012a). In the general population, the incidence of anaphylaxis is on the increase (Department of Health, 2006), probably associated with a notable increase in the prevalence of allergic diseases in the last 30 years (Resuscitation Council (UK), 2012a).

The recent death of a patient, who suffered an anaphylactic reaction and died in a dental practice in Brighton following treatment with corsodyl mouthwash (BBC, ), stresses the need for all dental practitioners to be able to recognize and effectively manage anaphylaxis. The Resuscitation Council (UK) (2012a) and NICE (2011) have published guidelines for the management of anaphylaxis.

The aim of this chapter is to understand the emergency management of anaphylaxis.

DEFINITION

Anaphylaxis can be defined as ‘a severe, life-threatening, generalised or systemic hypersensitivity reaction’ (Johansson et al., 2004). Basically, it is a life-threatening allergic reaction – the extreme end of the allergic spectrum (Anaphylaxis Campaign, 2013).

INCIDENCE

Available UK estimates suggest that approximately 1 in 1300 of the population of England has experienced anaphylaxis at some point in their lives (NICE, 2011). There has also been a dramatic rise in the rate of hospital admissions for anaphylaxis. Between 1990 and 2004 they increased from 0.5 admissions per 100,000 to 3.6 per 100,000, an increase of 700% (Gupta et al., 2007), and there are now around 20 deaths each year in the United Kingdom from anaphylaxis (although this may be a substantial underestimate) (NICE, 2011). In a survey of 620 dental surgeries, 7 had encountered anaphylaxis in the previous 12 month period (Müller et al., 2008).

Anaphylaxis is more common in females than in males. In 2004, 58% of attendees to emergency departments with anaphylaxis were female, 42% were male (Peng and Jick, 2004); Webb and Lieberman’s (2006) findings were comparable: 62% females and 38% males. The mean age of patient with anaphylaxis is 37 years (Webb and Lieberman, 2006).

From the author’s experience (feedback from dental practitioners), cases of anaphylaxis in the dental practice have been caused by a number of factors including local anaesthetic, latex, amoxycillin and metronidazole.

PATHOPHYSIOLOGY

Irrespective of the mechanism of anaphylaxis, mast cells and basophils release histamines and other vasoactive mediators which produce circulatory, respiratory, gastrointestinal and cutaneous effects (Wyatt et al., 2012). These effects can include the development of pharyngeal and laryngeal oedema, bronchospasm, decreased vascular tone and capillary leak causing circulatory collapse (Jevon, 2004).

CAUSES

Causes of anaphylaxis include:

• drugs, e.g. penicillin, aspirin, local anaesthetic, surface anaesthetics (e.g. benzocaine);
• bee/wasp stings;
• foods, e.g. peanuts, tomatoes, fish;
• latex.

Source: British Medical Association and Royal Pharmaceutical Society (2013), Jevon (2008), Anaphylaxis Campaign (2013)

Table 8.1 lists suspected triggers for fatal anaphylactic reactions in the United Kingdom between 1992 and 2001 (Pumphrey, 2004). When anaphylaxis is fatal, death usually occurs very soon following contact with the trigger (Resuscitation Council (UK), 2012a). In fatal food anaphylactic reactions, respiratory arrest usually occurs after 30–35 minutes; in fatal insect sting anaphylactic reactions, cardiovascular shock usually occurs after 10–15 minutes; and in fatal intravenous medication anaphylactic reactions, cardiac arrest occurs most commonly within 5 minutes (Pumphrey, 2000). Death never occurred more than 6 hours after contact with the trigger (Pumphrey, 2000).

Anaphylaxis can also be associated with additives and excipients (an excipient is an inactive substance that serves as a vehicle or medium for a drug (Soanes and Stevenson, 2006)). It is therefore recommended to check the full formula of preparations, including those for topical application, especially those intended for use in the mouth (British Medical Association and Royal Pharmaceutical Society, 2013).

In approximately 40% of anaphylactic reactions, the cause is unknown (idiopathic anaphylaxis) (Webb and Lieberman, 2006; Greenberger, 2007).

Local anaesthetic

Following the administration of a local anaesthetic, a minority of patients may suffer one of a range of unwanted symptoms. Some of these symptoms can be mistaken for hypersensitivity or allergy and the patient unnecessarily told they are allergic to the anaesthetic (Henderson, 2011). Allergy to local anaesthetic is rare (more likely with the ester local anaesthetic agents – not used routinely in dentistry) (Henderson, 2011). Due to the rarity of local anaesthetic allergy, if a patient experiences signs and symptoms suggestive of an allergic response, it is prudent to consider other possible causes of the symptoms, e.g. toxicity (sedation, light headedness, slurred speech, mood alteration, diplopia, disorientation and muscle twitching) (Henderson, 2011).

CLINICAL FEATURES AND DIAGNOSIS

The lack of a consistent clinical picture can sometimes make an accurate diagnosis difficult (Project Team of the Resuscitation Council (UK), 2012a). Anaphylaxis can vary in severity and the process can be slow, rapid or biphasic; occasionally the onset may be delayed by a few hours and e/>