Unit 4 Allergies and
Immune Responses
• Every year, at least 1,000 Americans die of allergic reactions.
When managing allergy-related emergencies, you must be
aware of the possibility of acute airway obstruction and
cardiovascular collapse and be prepared to treat these lifethreatening complications.
• You must also be able to distinguish between the bodys usual
response to a sting or bite and an allergic reaction, which may
require epinephrine.
• Your ability to recognize and manage the many signs and
symptoms of allergic reactions may be the only thing standing
between a patient's life and imminent death.
• The immune system protects the human body from
substances and organisms that are foreign to the body
Without the immune system for protection, life as you know it
would not exist.
an allergic reaction, an exaggerated immune response to any •
substance, is not caused directly by an outside stimulus, such
as a bite or sting. Rather, it is a reaction by the body's immune
system, which releases chemicals to combat the stimulus..
• Among these chemicals are histamines and leukotrienes, both
of which contribute to an allergic reaction. An allergic reacrion
may be mild and local, involving hives, itching, or tenderness,
or it may be severe and systemic, resulting in shock and
respiratory failure
• Anaphylaxis is an extreme allergic reaction that is life
threatening and involves multiple organ systems. In severe
cases, anaphylaxis can rapidly result in death.
• One of the most common signs of anaphylaxis is wheezing, a
high-pitched, whistling breath sound that is typically heard on
expiration, usually resulting from
• broncho spasm,/bronchoconstriction and increased mucus
production
• Urticaria consists of small areas of generalized itching or
burning that appear as multiple, small, raised areas on the
skin
• You may also note hypotension as a result of hypovolemic
shock due to increased capillary permeability .
The most common allergens, however, fall
into the following five general categories:
• 1- Insect bites and stings
• When an insect bites you and injects the bite with its venom,
the act is called envenomation.
• The reaction may be local, causing swelling and itchiness in the
surrounding tissue, or it may be systemic, involving the entire
body. Such a total body reaction would be considered
an anaphylactic reaction.
•
• 2-Medications.
• injection of medications such as penicillin may cause an
immediate (within 30 minutes) and severe allergic reaction .
• However, reactions to oral medications, such as oral penicillin,
may be slower in onset (more than 30 minutes) but equally
severe.
• 3-Plants.
• individuals who inhale dusts, pollens, or other plant materials
to which they are sensitive may experience a rapid and severe
allergic reaction.
• 4-Food.
• Eating certain foods, such as shellfish or nuts, may result in a
relatively slow (more than 30 minutes) reaction that still can
be quite severe. The person may be unaware of the exposure
or inciting agent.
• 4-Chemicals.
• Certain chemicals, makeup, soap, latex, and various other
substances can cause severe allergic reactions.
Primary Assessment
• When a patient presents with an allergic reaction, you should
perform a rapid scan of the patient to identify and treat any
immediate or potential life threats. By paying careful attention
to the patients ABCs, you will be able to maintain breathing
and circulation until you are able to transport the patient to
the emergency department.
• form a General Impression
• Allergic reactions may present as respiratory distress or as
cardiovascular distress in the form of shock.
• Patients experiencing a severe allergic reaction will often be
very anxious and feel like they are going to die
• Airway and Breathing
• The most severe form of allergic reactions, anaphylaxis, can
cause rapid swelling of the upper airway. You may have only
a few minutes to assess the airway and provide lifesaving
measures; however, not all allergic reactions are
anaphylactic reactions
• Work quickly to assess the patient to determine the severity
of the symptoms.
• Position the conscious patient in a tripod position leaning
forward. This will help to facilitate air entry into the lungs and
may help the patient to relax.
• Quickly listen to the lungs on each side of the chest. If
wheezing or a silent chest is heard, the lower airways are also
closing, preventing oxygen from entering the circulatory
system.
• Do not hesitate to initiate high-flow oxygen therapy
• You may have to assist with ventilations for a patient in severe
respiratory distress with a severe allergic reaction. This can be
done in a semi responsive or an unresponsive patient.
• The positive-pressure ventilations you provid will force air
through the swelling in the throat and into the lungs while you
are waiting for more definitive treatment. In severe situations
such as these, the definitive care needed is an injection of
epinephrine.
• Circulation
• some patients in anaphylaxis may not present with severe
respiratory symptoms but primarily with signs and symptoms
of circulatory distress, such as hypotension.
• Palpating a radial pulse will help you to identify how the
circulatory system is responding to the reaction.
• If the patient is unresponsive and without a pulse, begin basic
life support measures or use an automatic external
defibrillator if necessary
• Assess for a rapid pulse rate; pale, cool, cyanotic or red, moist
skin; and delayed capillary refill times that indicate hypo
perfusion.
• Your initial treatment for shock should include oxygen,
positioning in a shock position, and maintaining normal body
temperature.
• The definitive treatment for anaphylactic shock is epinephrine
• Transport Decision
• Always provide prompt transport for any patient who may
be having an allergic reaction. Take with you all medications
and auto-injectors the patient has at the time.
History taking
• SAMPLE History If the patient is responsive, begin with
obtaining the SAMPLE history and asking the following
questions specific to an allergic reaction: Have any
interventions already been completed? Do you have any
prescribed, preloaded medications for allergic reactions?
Secondary assessment
• Physical Examinations The secondary assessment may help
direct treatment. Perform evaluations of the respiratory
system. Thoroughly assess breathing, including increased work
of breathing, use of accessory muscles, head bobbing, tri- pod
positioning, nostril flaring, and grunting. Carefully auscultate
both the trachea and the chest.
• Wheezing occurs because of narrowing of the air passages,
which is mainly the result of contraction of muscles around
the bronchioles in reaction to the allergen, and mobilization of
mucus in an attempt to "push" out the allergen
• Stridor, a harsh, high-pitched inspiratory sound, occurs when
swelling in the upper airway (near the vocal cords and throat)
closes off the airway and can eventuaily lead to total
obstruction.
• Carefully assess the skin for swelling, rash, hives, or signs of
the source of the reaction: bite, sting, or con- tact marks. A
rapidly spreading rash can be concerning because it may
indicate a systemic reaction. Red, hot skin may also indicate a
systemic reaction as the blood vessels lose their ability to
constrict and blood moves to the extremities.
• Vital Signs
• Assess baseline vital signs, including pulse, respirations,
blood pressure, skin, pupils, and oxygen saturation. Rapid,
labored breathing indicates airway obstruction. Rapid
respiratory and pulse rates may indicate respiratory distress
or systemic shock.
• Fast pulses and hypotension are ominous signs, indicating
systemic vascular collapse and shock. Skin signs may be an
unreliable indicator of hypo perfusion because of rashes and
swelling.
Emergency medical care for
immunological emergency
If the patient appears to be having a severe allergic (or
anaphylactic) reaction, you should administer basic life
support at once and provide prompt transport to the hospital,
 reassessing vital signs every 5 minutes if the patient's
condition is unstable or every 15 minutes if the patient's
condition is stable.
Place the patient in a position of comfort. Consider the
Trendelenburgs position for hypotensive patients and patients
showing signs and symptoms of shock.
 In addition to providing oxygen, you should be prepared to
maintain a patent airway or administer cardiopulmonary
resuscitation
If the allergic reaction was caused by a sting and the stinger is
still present, attempt to scrape it away using a hard object,
such as a credit card.
Placing ice over the injury site has been thought to slow
absorption of the toxin and diminish swelling, but ice packs
placed directly on the skin may freeze the skin and cause more
damage.
 in some areas, you may be allowed to
administer epinephrine or assist the patient with epinephrine
administration.
Epinephrine
• Epinephrine has various properties that cause the blood
vessels to constrict, which reverses vasodilation and
hypotension; this, in turn, elevates the diastolic pressure and
improves coronary blood flow.
• Other properties of epinephrine increase cardiac contractility
and relieve brocho spasm in the lungs. Because epinephrine
has immediate action, it can rapidly reverse the effects of
anaphylaxis.
• The indications for administering epinephrine include a severe
allergic reaction and hypersensitivity to an exposed substance.