Case 3 l An Unpleasant Surprise

 

Case 3 l An Unpleasant Surprise " ODELL'S CLINICAL PROBLEM "

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Summary of "An Unpleasant Surprise" case

• A 17-year-old female patient becomes unwell, developing shortness of breath and a facial rash in your dental reception. What would you do?

 

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 also has eczema, as do her mother and brother, and she uses a topical corticosteroid cream, as prescribed. The patient has no known drug allergies.

Examination

• 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 oedematous areas may 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:

1. a red urticarial rash
2. oedema that may obstruct the airway
3. hypotension caused by reduced peripheral resistance
4. hypovolaemia caused by the movement of fluid out of the circulation into the tissues
5. 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.

1. Reassure the patient.
2. Assess vital signs, including blood pressure, pulse and respiratory rate.
3. Have the patient lie flat (because there is no difficulty breathing).
4. Call for help.
5. 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 erythematous areas seen are slightly raised.