|
Anaphylaxis is a severe, acute, systemic -
involving the whole body, life-threatening type of allergic reaction which
occur in all age groups. In the classic form of anaphylaxis, there is a
prior exposure to a substance and the person becomes sensitized to that
substance. Re-exposure to the same substance produces the allergic reaction.
Anaphylactoid reaction however is not immune mediated.
Common substances that cause anaphylaxis include foods like peanuts, eggs,
milk, shellfish, and fish. It may also be caused by drugs like NSAIDS,
antibiotics (cephalosporins or penicillin), IV contrast materials, or latex
such as gloves.
Exposure to any of these substances cause the tissues to release mediators
like histamine or leukotriene and these cause the signs and symptoms
affecting the entire body.
There can be lower airway edema producing airway constriction leading to
symptoms of wheezing and difficulty of breathing. When the upper respiratory
tract is involved there is nasal congestion, hoarseness or stridor. There
can also be respiratory arrest due to airway obstruction in severe cases
making the condition life-threatening.
When the condition is mild there can be no cardiovascular symptoms. If
severe there is increased capillary permeability so that fluid leaks from
the capillaries into the interstitial compartment leading to decreased
intravascular volume thus producing the symptom of decreased blood pressure.
Shock may occur. The fluid can also leak to the air sacs in the lungs
producing pulmonary edema.
Hives appear on the skin. These are common in the throat, lips, palms and
soles, and other areas of body. Angioedema may also occur.
There may also be gastrointestinal symptoms like abdominal pain, nausea,
vomiting, or diarrhea especially if the allergy is secondary to food.
Other symptoms include tearing and itchiness of the eyes, restlessness due
to pruritus, confusion, blueness of the skin or nail beds, anxiety, tremor,
palpitation, slurred speech, and dizziness.
When anaphylaxis is prolonged this may cause irregular beating of the heart
called arrhythmia. Arrythmia together with decrease in blood pressure and
airway obstruction may cause death.
Anaphylaxis therefore is a medical emergency. It is important that the
patient’s airway, breathing, and circulation (ABCs) be assessed.
Admistration of IV fluid must be done and the patient must be given
epinephrine injection to open the airway and constrict the blood vessels.
Tracheostomy or endotracheal intubation can be done if there is airway
compromise. Once the patient has been stabilized he should be given
antihistamines.
|