Case Scenario
A 17-year-old female patient becomes unwell, developing shortness of breath and a facial rash in your dental reception. What would you do?Table of Contents
History
Complaint
The patient complains that she feels unwell, hot and breathless. Her face is itchy.History of Complaint
The patient was attending for a planned restoration under local anaesthesia. Her symptoms developed whilst sitting in the waiting room eating a snack bought from a shop next door.Medical History
You check your last medical history in the patient’s notes and discover that the patient has asthma, which is well controlled, and is taking salbutamol on occasions. She alsohas eczema, as do her mother and brother, and she uses a topical corticosteroid cream, as prescribed. The patient has no known drug allergies.Examination
What do you see in photo?There is patchy erythema. In the most inflamed areas, there are well-defined raised oedematous weals, for instance, just above the lower border of the mandible below the commissure.
Diagnosis
What is the Likely Diagnosis?This is a typical urticarial rash, which indicates a type 1 hypersensitivity reaction. The rash, together with the systemic symptoms, indicates anaphylaxis arising from hypersensitivity to an unknown allergen. As the patient has not yet been exposed to any allergens in the dental surgery environment, the cause is most likely a food allergen, and the most likely cause of a severe reaction like this is peanuts.
What Does Urticarial Mean?
The word urticarial comes from the Latin for nettle rash. An urticarial rash causes superficial oedema that may form separate, flat, raised blister-like patches or be diffuse. In the head and neck region, swelling is often diffuse because the tissues are lax. Markedly edematous areas ma become pale because of compression of their blood supply, but the background is erythematous. Patients often know an urticarial rash by the lay term hives.
What are the Signs and Symptoms of Anaphylaxis?
The signs and symptoms vary with severity. The classic picture is of:
- A red urticarial rash
- Edema that may obstruct the airway
- Hypotension caused by reduced peripheral resistance
- Hypovolaemia caused by the movement of fluid out of the circulation into the tissues
- Obstruction of small airways caused by oedema and bronchospasm.
Involvement of nasal and ocular tissues may cause rhinitis and conjunctivitis. There may also be nausea and vomiting.
What is the Pathogenesis of Anaphylaxis?
Anaphylaxis is an acute type 1 hypersensitivity reaction triggered in a sensitized individual by an allergen. The allergen enters the tissues and binds to immunoglobulin E (IgE) acting as a receptor on the surface of mast cells, which are present in almost all tissues. Binding induces degranulation and the release of large amounts of inflammatory mediators, particularly histamine. These cause vasodilatation, increased capillary permeability and bronchospasm.
Type 1 Hypersensitivity is Also Known As Immediate Hypersensitivity. Why?
Because acute anaphylactic reactions may occur within seconds. However, it is important to remember that reactions may be delayed for up to an hour, depending on the nature of the allergen and the route of exposure. In general, allergens administered intravenously cause immediate reactions, and those administered intramuscularly after approximately 30 minutes. It takes around 45 minutes for an orally administered allergen such as an antibiotic to be absorbed, pass through the circulation to the tissues and trigger a reaction. However, particular allergens can cause an anaphylactic reaction very quickly, whether applied topically or ingested, and important examples are peanuts and latex.What Would You Do Immediately?
The immediate cause of the reaction is not important, as all anaphylactic reactions are treated similarly.
- Reassure the patient.
- Assess vital signs, including blood pressure, pulse and respiratory rate.
- Have the patient lie flat (because there is no difficulty breathing).
- Call for help.
- Obtain oxygen and your practice’s emergency drug box.
On examining for the signs noted above, you discover that the patient, previously breathing without difficulty, is now breathless, and a wheeze can be heard on expiration, indicating bronchospasm. She feels hot and has a pulse rate of 120 beats/min and blood pressure of 120/80 mmHg. She is conscious, but the effects are becoming more severe, and the rash now affects all the face and neck regions and has spread onto the upper aspect of the thorax and arms. The appearance of one arm is shown. The erythematous areas seen are slightly raised.
Treatment
What Would You Do Next?Before the breathing problems were noted, you correctly laid the patient flat. However, her lungs must now be raised above the rest of her body to prevent edema fluid collecting in the lungs.
Allow the patient to adopt the most comfortable position for breathing, and give:
• Continue to monitor the vital signs.
• Continue to administer oxygen.
- Oxygen (5 l/min) via a facemask. Because there is bronchospasm, give the following drugs:
- Adrenaline/epinephrine. 1:1000, 500 micrograms IM. The easiest form to administer is a preloaded ‘EpiPen’ or ‘Anapen’, both of which are available for adults (300 micrograms/dose) and children (150 micrograms/dose). Alternatively, a Min-I-Jet prepacked syringe and needle assembly or a standard vial of adrenaline/epinephrine solution, both containing 1 mg in 1ml (1:1000), may be used. However, both these latter methods require a delay in administration to prepare the injection. You need to be familiar with whichever form is held in your practice because delay in calculating doses and volumes is clearly undesirable. Adrenaline/epinephrine may also be given subcutaneously, but the absorption is slower, and this route is no longer recommended. Note that autoinjectors are designed for self-administration and so provide a slightly lower dose than is recommended. The recommended site for the intramuscular injection is the anterolateral aspect of the middle of the thigh, where there is most muscle bulk. If clothing prevents access, the upper lateral arm, into the deltoid muscle, is an alternative site. In an emergency, it may be necessary to inject through clothing but this is not recommended. In the past, the tongue has been proposed as a potential site because it is familiar to dentists, but it is highly vascular, allowing rapid uptake of the drug and is unlikely to be acceptable to the conscious patient.
- Salbutamol. This β2 agonist may be helpful in patients experiencing respiratory distress. As the patient has asthma, she may have an inhaler with her and could be asked to take a dose. However, this is secondary to ensuring rapid delivery of adrenaline/epinephrine. Adrenaline/epinephrine is the life-saving drug and must be given without delay, before circulatory collapse. It is rapidly acting and will counteract pulmonary oedema or bronchospasm. After Giving a Single Dose of Adrenaline/Epinephrine with an Autoinjector, the Patient Recovers. What
• Continue to monitor the vital signs.
• Continue to administer oxygen.
• Arrange transfer of the patient to a hospital.
• Advise the patient of the need for formal investigation of her probable allergy.
• Advise the patient of the need for formal investigation of her probable allergy.
No, definitely not. The response of the patient needs to be closely observed. Adrenaline/epinephrine is highly effective but has a very short half-life. Recurrence of bronchospasm, a drop in blood pressure or worsening oedema indicates a need for further adrenaline/epinephrine. In a severe reaction, this is likely to be needed about 5 minutes after the previous administration, and it can be repeated again as often as necessary. Late relapse, hours later, is also possible. Mast cells release potent inflammatory mediators other than histamine, and some have long half-lives.
Can an Anaphylactic Reaction Be Controlled Without Adrenaline/Epinephrine?
If the only features are a rash and mild swelling not involving the airway, it may be appropriate to give oral chlorphenamine (chlorpheniramine). However, if there is any suggestion of bronchospasm, hypotension or oedema around the airway, adrenaline/epinephrine will be needed. Adrenaline/epinephrine should be administered as early as possible to be effective, and it is better not to delay unless the signs and symptoms are very mild and of slow onset.
What Additional Treatment Will Be Provided in the Hospital?
Once appropriate medical care arrives or the patient is admitted to the emergency department, the following treatment will be commenced:
• Chlorphenamine (chlorpheniramine) 10 mg intravenously will counteract the effects of histamine.
• Hydrocortisone 200 mg intravenously or intramuscularly.
• Intravenous fluid only required if hypotension develops. A suitable regime would be 500–1000 ml of normal saline infused over 5 minutes with continuous monitoring of vital signs.
The presentation of drugs useful for anaphylaxis is
Why is Adrenaline/Epinephrine Effective?
Adrenaline/epinephrine is the prototypical adrenergic agonist and has both α and β receptor activity. Alpha receptor–mediated action on arterioles causes vasoconstriction and, thus, reverses oedema. Beta receptor–mediated actions include increasing the cardiac output by increasing the force of contraction and heart rate (β1) and bronchodilatation (β2). Mast cell degranulation is also suppressed.
Could You Have Predicted That This Patient Wa At Risk of Anaphylaxis?
She has a history of asthma and a family history of eczema. This indicates atopy and carries an increased risk of developing hypersensitivity to a wide range of substances. However, not all patients with atopia develop severe reactions like this. It is important to take a thorough allergy history, particularly regarding drugs, rubber and other dental materials, as well as foods, in all patients. No patients with potential allergies should be exposed to their possible allergens until you have sought advice.
Why Did This Patient Have No History of Severe Allergy?
This underlines the unpredictability of allergic reactions and why patients who have been administered any medication should be monitored for an appropriate time in case of adverse effects, the period depending on the route of administration (see above). In this instance, the patient may have been sensitized by previous exposure to allergens such as peanut or other foods relatively recently. Although there is no evidence yet that peanut was the causative allergen, this is a definite possibility. Most dietary allergies start in childhood, but adults, even older adults, can develop allergy to nuts despite having consumed them without problems for many years. Adults who seem to have outgrown their childhood nut allergy can experience a relapse in later life. Lack of an allergy history is also important with regard to penicillins because sensitization to very small quantities of penicillins in the environment may develop. Veterinary uses of penicillins leave residues in meat and milk, and these may be passed on to babies via their mother’s milk. Penicillins are ubiquitous, and there is probably a genetic predisposition to explain why only a few individuals develop hypersensitivity.
Can Patients Be Tested for the Causative Allergen?
Yes, but it carries a risk of anaphylaxis and must be performed with care in a specialized centre. Unlike mild food allergies and intolerances, which are suspected in approximately twice as many individuals as those who actually suffer from them, severe food allergies are usually obviously authentic and often multiple. Testing is indicated because severe food allergy often strikes away from medical care and is not infrequently fatal. For penicillin allergy, the most likely allergen to be administered by a dentist, only 10–20% of patients who report penicillin allergy are actually hypersensitive, and testing is reserved for those who give a convincing history of a type 1 reaction and who also have a definite requirement for penicillin. In most cases, a safe alternative antibiotic, for example, clindamycin, is available and so testing is not performed.
Why is There No Corticosteroid or Antihistamine in My Dental Emergency Drugs Box, Which is Claimed To Contain the Drugs Recommended for the UK?
The Resuscitation Council UK has published guidance on medical emergencies and resuscitation, revised in May 2008. Its recommendations have been endorsed by the General Dental Council, which states that emergency drugs, listed in table below, should be available in all dental surgeries in the UK.
Emergency Drugs
| Drug | Dose |
|---|---|
| Glyceryl trinitrate spray | 400 micrograms/dose |
| Salbutamol aerosol inhaler | 100 micrograms/puff |
| Adrenaline/epinephrine injection | 1 : 1000 1 mg/ml |
| Aspirin dispersible | 300 mg |
| Glucagon injection | 1 mg |
| Oral glucose solution | Gel, tablets or powder |
| Midazolam | 5 mg/ml or 10 mg/ml |
| Oxygen |
The recommended drugs for this case are oxygen and adrenaline/epinephrine, which are required to be kept in every practice. The guidance specifically notes that antihistamines and corticosteroids are not first-line drugs for the treatment of anaphylaxis and that their administration is not expected of dental practitioners in primary care. This is because it is difficult to achieve intravenous access in an individual with reduced circulatory volume and hypotension. Identifying and cannulating a collapsed vein is difficult even for the experienced and is best attempted as soon as adrenaline/epinephrine has taken effect. If competent, the dentist could help later treatment by gaining intravenous access in advance of medical help arriving and placing a cannula for later use. This may be made easier by massaging the arm towards the hand to try to inflate the vein. Maintaining this drug box is a minimum requirement for general practice only. Much more diverse emergency drug boxes are used by those working in hospitals, health clinics and some specialist practices, where dentists may be trained in immediate life support or have other specialist skills through their involvement in conscious sedation or special care dentistry. The list must also be modified according to circumstances. In remote areas where medical help may not be immediately available, it may be essential to have the additional drugs for longer-term treatment and also for the dentist to be able to gain venous access. These drugs and skills should be within the remit and capabilities of any dental practitioner, with appropriate training. Dentists must be familiar with the actions and effects of drugs they may need to use, so it is the dentists’ responsibility to ensure that they are properly informed about any additional drugs they elect to hold. The General Dental Council also provides guidance that every practice should have available two people trained in medical emergencies whenever such treatment is being carried out. All members of the dental team must practise their skills in simulated emergencies on a regular basis. Patients with severe allergies may be issued with adrenaline/epinephrine autoinjectors to carry with them at all times, and it is now recommended that they carry two because the dose in one may be insufficient to treat a severe reaction. Patients who carry these devices should be asked to bring them to all dental appointments.
If You Discovered That You Had Just Administered a Penicillin Orally To a Patient Known To Be Allergic
To Penicillins, What Would You Do?
Absorption of only a very small amount of the penicillin is needed to trigger an allergic response, so there is no point in thinking that inducing vomiting would be helpful. The best thing to do would be to administer chlorphenamine (chlorpheniramine) and steroid immediately if available. As they may well not be, call an ambulance, and prepare the adrenaline/epinephrine injection and oxygen; administer adrenaline/epinephrine immediately if any signs begin to develop. The patient would still have to seek medical care as soon as possible because the late phases of the reaction might still develop even if the immediate phases were prevented.
Suppose the Patient Had Been a Child?
Allergy in children is usually triggered by dietary allergens rather than drugs; however, latex allergy is possible, and children with frequent medical exposure to latex, as in catheters, are at risk. Doses of adrenaline/epinephrine are reduced to 300 micrograms for ages 6–12 years and 150 micrograms for children under 6 years. Giving these doses might prove difficult if you do not have specific paediatric formulations in your emergency drug kit. Autoinjectors provide 300 or 150 micrograms, and Min-I-Jet devices are designed to give a full adult dose. Children with severe allergies may carry autoinjection devices with the correct paediatric dose and should be asked to bring them when they attend for dental treatment.
What Allergens are Important in Dental Surgeries?
Perhaps surprisingly, contact reactions to amalgam and other restorative materials are the most commonly reported, but these are topical, not anaphylactic and not life threatening. The fact that these are now the commonest reported reactions is a result of the systematic exclusion of other more significant allergens from the dental environment over recent decades. Latex causes severe reactions and was previously a significant risk in those sensitized, but natural latex is now completely excluded from gloves, rubber dam and other materials in the UK, although it remains in use elsewhere. Powdered latex gloves are particularly allergenic and cause severe reactions if the powder is inhaled by a sensitized individual. Dental staff members are now more at risk than patients because they regularly handle a range of materials containing acrylates, eugenol and formaldehyde and will have been exposed to latex in the past. In the UK, the most significant risk for a severe anaphylactic reaction probably arises from prescription or administration of a penicillin to a patient allergic to it.