Anaphylaxis is an acute, potentially fatal reaction of the multi-organ system caused by releasing chemical mediators from Mastocytes and Basophils.
The classic form implies a prior sensitization to an Allergen with subsequent re-exposure, producing symptoms through an immunological mechanism.
Signs and symptoms
Anaphylaxis most commonly affects the cutaneous, respiratory, cardiovascular, and gastrointestinal systems. The skin or mucous membranes are involved in 80-90% of cases.
Most adult patients have some combination of urticaria, erythema, pruritus, or angioedema.
However, for poorly understood reasons, children may more commonly present with respiratory symptoms followed by skin symptoms.
It is also important to note that some of the most severe cases of Anaphylaxis occur in the absence of skin findings.
Initially, patients often experience itching and redness. Other symptoms can evolve rapidly, such as the following:
- Dermatological/ocular: Redness, urticaria, angioedema, cutaneous and conjunctival injection or pruritus, heat, and swelling.
- Respiratory: nasal congestion, coryza, rhinorrhea, sneezing, tight throat, wheezing, difficulty breathing, cough, hoarseness, dyspnea.
- Cardiovascular: dizziness, weakness, syncope, chest pain, palpitations.
- Gastrointestinal: dysphagia, nausea, vomiting, diarrhea, swelling, cramps.
- Neurological: headache, dizziness, blurred vision, and seizures (rare and often associated with hypotension).
- Other: metallic taste, sense of imminent death.
Diagnosis of Anaphylaxis
Anaphylaxis is mainly a clinical diagnosis.
The priority in the physical examination should be to assess the respiratory tract, respiration, circulation, and the adequacy of the patient’s activity (e.g., alertness, orientation, coherence of thought).
The test may reveal the following findings:
- General appearance and vital signs vary according to the severity of the anaphylactic episode and the system (s) of affected organs; Patients are generally restless and anxious.
- Respiratory findings: Severe angioedema of the tongue and lips; tachypnea; stridor or severe hunger for air; loss of voice, hoarseness, and dysphonia; wheezing
- Cardiovascular: tachycardia, hypotension; Cardiovascular collapse and shock can occur immediately, without any other finding.
- Neurological: depressed level of consciousness or can be agitated and combative.
- Dermatological: the classic cutaneous manifestation is urticaria (that is to say, urticaria) in any part of the body; Angioedema (soft tissue swelling); generalized erythema (whole-body) (or flushing) without urticaria or angioedema.
- Gastrointestinal: vomiting, diarrhea, and abdominal distension.
Laboratory studies are usually not necessary and are rarely helpful.
However, if the diagnosis is not precise, especially with a recurrent syndrome, or if other diseases should be excluded, the following laboratory studies can be ordered in specific situations:
- Serum tryptase may help confirm the diagnosis of Anaphylaxis.
- 24-hr urine histamine can help in the diagnosis of recurrent Anaphylaxis.
- If the carcinoid syndrome is considered, urinary levels of 5-hydroxy indole acetic acid in 24 hours.
Skin tests, immunoglobulin E (IgE) tests, in vitro, or both may determine the stimulus that causes the anaphylactic reaction. Such studies may include the following:
- Allergy test (s) to food.
- Allergy test (s) to the medication.
- Tests of causes of independent reactions of immunoglobulin E (IgE).
Supportive care for patients with suspected Anaphylaxis includes the following:
- Airway management (e.g., ventilator support with bag/valve/mask, endotracheal intubation)
- High flow oxygen
- Cardiac monitoring and pulse oximetry
- Intravenous access (large hole)
- Resuscitation with fluid with isotonic crystalloid solution
- Supine position (or comfort position if you have dyspnea or vomiting) with your legs elevated
The main pharmacological treatments for acute anaphylactic reactions are epinephrine and antihistamines H1. The medications used in patients with Anaphylaxis include the following:
- Adrenergic agonists (e.g., Epinephrine)
- Antihistamines (eg, diphenhydramine, hydroxyzine)
- H2 receptor antagonists (e.g., Cimetidine, ranitidine, famotidine)
- Broncodilatadores (p. Ej., Albuterol)
- Corticosteroids (e.g., methylprednisolone, prednisone)
- Positive inotropic agents (e.g., Glucagon)
- Vasopresores (p. Ej., Dopamina)
Education for counseling is crucial, especially in younger patients with food anaphylaxis.
Important problems include:
- Cross-contamination and inadequate labeling of food.
- A study of children with food allergies who visited a subspecialty allergy clinic found that 59% had an epinephrine autoinjector. However, 71% of parents reported that they kept the autoinjector available.
- The epinephrine autoinjection instruction was the only variable positively associated with having an autoinjector available.
- Patients with sensitivity to multiple antibiotics should receive a list of alternative antibiotics. They can present this list to their primary care physicians when antibiotic therapy is required.
- Education about promotion is also essential for people who are hypersensitive to insect bites.
- Warn patients to avoid using perfumes or hygiene products, particularly floral fragrances, as they attract flying hymenopterans.
- Brightly colored clothing attracts bees and other pollinating insects.
- Avoid locations of known hives or nests and avoid using equipment that alters the pack.
- People sensitive to Hymenoptera and who must be outdoors should carry an epinephrine autoinjector (see below).
- Inform patients who react to Hymenoptera venom of the availability of desensitization therapy.
- At discharge, warn patients of the possibility of recurrent symptoms and direct them to seek additional care if this occurs.
The practice parameter states that patients with a possible systemic reaction should be referred to an allergist or immunologist. They should be informed about the risk of another comeback, their preventive treatment options, and the benefits of wearing an identification bracelet or necklace. medical
Avoid insect bites and deal with an emergency.
Good evidence suggests that doctors prescribe less Epinephrine and that patients (or their parents) do not use Epinephrine as quickly as possible.
Consequently, at the time of discharge, all patients should receive an epinephrine autoinjector and receive adequate instructions on self-administer in a subsequent episode.
Patients should be instructed to maintain an epinephrine autoinjector with them at all times; They should also take Diphenhydramine and take this along with the Epinephrine autoinjector. They should be required to keep the device away from extreme temperatures.
Epinephrine is sensitive to both light and temperature and, therefore, should not be stored, for example, in a refrigerator or the glove compartment of a motor vehicle.
They should also receive instructions to replace any Epinephrine autoinjector before expiration.
Patients should be id to have quick and immediate access to emergency medical services for transportation to the nearest emergency service for treatment.
They should also receive instructions for emergency medical attention immediately after Epinephrine is injected because the effect is short-lived (<15 min), and biphasic reactions may occur.
An epinephrine autoinjector (e.g., EpiPen) for adults is available with a single 0.3 mg (1: 1,000 v / v) dose.
Similarly, an EpiPen Jr., with a dose of 0.15 mg (1: 2,000 v / v), is available for children weighing less than 30 kg. Audi-Q comes in a similar dosage and is a more compact device that provides visual and audio signals to help with proper administration.
Adrenaclick is also available as a single-dose autoinjector of 0.15 mg or 0.3 mg.
The Twinject is a device the size of a pen that contains two doses of Epinephrine available as a 0.15 or 0.3 mg formulation.
The first doses are administered by autoinjection in both cases, and the second is injected manually.