Chapter 18
Immunologic
Emergencies
National EMS Education
Standard Competencies (1 of 2)
Medicine
Applies fundamental knowledge to provide
basic emergency care and transportation
based on assessment findings for an acutely
ill patient.
National EMS Education
Standard Competencies (2 of 2)
Immunology
• Recognition and management of shock and
difficulty breathing related to:
– Anaphylactic reactions
• Anatomy, physiology, pathophysiology,
assessment, and management of:
– Hypersensitivity disorders and/or emergencies
– Anaphylactic reactions
Introduction (1 of 2)
• At least 1,000 Americans per year die of
allergic reactions.
• Allergy-related emergencies may involve:
– Acute airway obstruction
– Cardiovascular collapse
Introduction (2 of 2)
• You must be able to treat these lifethreatening complications.
• Immunology is the study of the body’s
immune system.
Anatomy and Physiology
• Immune system protects the body from
foreign substances and organisms.
• When a foreign substance invades the
body:
– Body goes on alert.
– Body initiates a series of responses to inactivate
the invader.
Pathophysiology: Allergic
Reaction (1 of 2)
• An allergic reaction is an exaggerated
immune response to any substance.
• Not caused directly by an outside stimulus
• Caused by the body’s immune system
– Releases chemicals to combat stimulus
– Include histamines and leukotrienes
Pathophysiology: Allergic
Reaction (2 of 2)
• Caused by the body’s immune system
– Releases chemicals to combat stimulus
– Include histamines and leukotrienes
• Allergic reaction may be mild and local, or
severe and systemic.
Pathophysiology:
Anaphylaxis (1 of 3)
• Anaphylaxis is an
extreme, lifethreatening allergic
reaction.
– Involves multiple
organ systems
– Wheezing is one of
the most common
signs.
Pathophysiology:
Anaphylaxis (2 of 3)
• Urticaria (hives) is
also present.
Source: © Chuck Stewart, MD
– Consists of small
areas of
generalized itching
or burning that
appear as multiple,
small, raised areas
on the skin
Pathophysiology:
Anaphylaxis (3 of 3)
• You may also note hypotension as a result
of hypovolemic shock.
Common Allergens (1 of 3)
• Insect bites and
stings
– When an insect bites
and injects the bite
with its venom, this
is called
envenomation.
– The reaction may be
local (swelling and
itchiness) or
systemic (involving
the entire body).
Common Allergens (2 of 3)
• Medications
– Penicillin injection
may cause an
immediate and
severe reaction.
Source: Courtesy of Carol B. Guerrero
– Oral penicillin may
take longer.
– A person will
typically experience
an allergic reaction
after becoming
sensitized.
Common Allergens (3 of 3)
• Plants
– Dusts, pollens, other plant materials
• Food
– Reaction can be relatively slow
– Shellfish, nuts
• Chemicals
– Makeup, soap, latex
Insect Stings (1 of 11)
• Death from stinging insects far outnumber
deaths from snakebites.
– Stinging organ of most insects is a small hollow
spine projecting from the abdomen.
– Venom can be injected directly into skin.
Insect Stings (2 of 11)
• Honeybees cannot
withdraw their
stinger.
– Fly away and die
• Wasps, hornets,
and fire ants can
sting multiple
times.
Source: A. © manfredxy/ShutterStock, Inc.
Source: B. © Heintje Joseph T. Lee/
ShutterStock, Inc.
Insect Stings (3 of 11)
• Some ants, especially the fire ant, also
strike repeatedly.
– Often inject a particularly irritating toxin at the
bite sites
Source: A. Courtesy of Scott Bauer/USDA
Source: B. © Chris
Harvey/ShutterStock, Inc.
Insect Stings (4 of 11)
• Signs and
symptoms include:
– Sudden pain
– Swelling
– Localized heat
– Redness in lightskinned individuals
– Itching and
possibly a wheal
Source: © Simon Krzic/ShutterStock, Inc.
Insect Stings (5 of 11)
• There is no specific treatment for these
injuries.
– Applying ice sometimes helps.
– Swelling may be dramatic and frightening.
– Local manifestations are not serious.
Insect Stings (6 of 11)
• Stinger of the
honeybee can
continue to inject
venom for up to
20 minutes.
• Attempt to remove the
stinger by scraping the
skin with the edge of a
sharp, stiff object such
as a credit card.
Insect Stings (7 of 11)
• Do not use tweezers or forceps.
• Wash the area with soap and water.
• Remove any jewelry from the area.
• Be alert for vomiting or signs of shock.
• Give oxygen if needed.
• Monitor the patient’s vital signs.
Insect Stings (8 of 11)
• About 5% of people may have anaphylactic
reactions from:
– Bees
– Hornets
– Yellow jackets
– Wasps
• Account for 200 deaths per year.
Insect Stings (9 of 11)
Insect Stings (10 of 11)
• Patients may experience:
– Generalized itching and burning
– Widespread urticaria
– Wheals
– Swelling of the lips and tongue
– Bronchospasm and wheezing
– Chest tightness and coughing
– Dyspnea
Insect Stings (11 of 11)
• Patients may experience (cont’d):
– Anxiety
– Abdominal cramps
– Hypotension
– Occasionally, respiratory failure
• If untreated, anaphylactic reaction can
proceed rapidly to death.
Patient Assessment (1 of 3)
• Scene size-up
• Scene safety
– Identify and address environmental hazards.
– Patient’s environment or activity may indicate
source of reaction.
– Never enter a scene where more than one
person is experiencing same symptoms.
Patient Assessment (2 of 3)
• Scene safety (cont’d)
– Follow standard precautions, with a minimum of
gloves and eye protection.
– Consider the need for additional or specialized
resources.
– Call for additional resources earlier rather than
later.
Patient Assessment (3 of 3)
• Mechanism of injury/nature of illness
– May not be an allergic reaction
– Trauma may have occurred.
– Determine the MOI/NOI.
– Look for bee stingers or chemicals and other
indications of a reaction.
Primary Assessment (1 of 5)
• Perform a rapid scan of the patient.
• Form a general impression.
– May present as respiratory or cardiovascular
distress in the form of shock
– Patients will be very anxious.
– Call for ALS backup if available.
– Try to get information on the chief complaint.
Primary Assessment (2 of 5)
• Airway and
breathing
– Anaphylaxis can
cause rapid swelling of
the upper airway.
– Only a few minutes to
assess the airway and
provide lifesaving
measures
– Work quickly to
determine the severity
of the symptoms.
Primary Assessment (3 of 5)
• Airway and breathing (cont’d)
– Position conscious patients in tripod position
and listen to the lungs.
– Do not hesitate to initiate high-flow oxygen.
– In severe situations, the definitive care is an
injection of epinephrine.
Primary Assessment (4 of 5)
• Circulation
– May present with hypotension
– Palpate for radial pulse.
• If the patient is unresponsive and without a
pulse, begin BLS or use an AED.
• If pulse is present, assess for a rapid pulse,
and check skin condition and capillary refill.
Primary Assessment (5 of 5)
• Initial treatment
– Oxygen
– Positioning
– Maintaining normal body temperature
• Transport decision
– Always provide prompt transport for any patient
who may be having an allergic reaction.
– Take along all medications and auto-injectors
the patient has at the time.
History Taking (1 of 4)
• Identify:
– Chief complaint
– History of present illness
– Associated signs and symptoms
– Pertinent negatives
History Taking (2 of 4)
History Taking (3 of 4)
• SAMPLE history
• If the patient is conscious, ask the following
questions:
– Have any interventions already been
completed?
– Do you have any prescribed, preloaded
medications for allergic reactions?
History Taking (4 of 4)
• Ask the following questions (cont’d):
– Do you have any respiratory symptoms?
– Do you have other symptoms?
– Have you had previous allergic reactions,
asthma, or hospitalizations?
– What were you doing or what were you exposed
to before the onset of symptoms?
Secondary Assessment (1 of 4)
• Physical examinations
– Includes a systemic head-to-toe or focused
assessment
– Thoroughly assess breathing, including:
• Increased work of breathing
• Use of accessory muscles
• Head bobbing, nostril flaring, grunting
• Tripod positioning
Secondary Assessment (2 of 4)
• Physical examinations (cont’d)
– Auscultate both the trachea and the chest.
– Wheezing may occur because of narrowing of
the air passages.
– Assess the circulatory system.
– Assess the skin for swelling, rash, hives, or
signs of the source of the reaction.
Secondary Assessment (3 of 4)
• Vital signs
– Assess baseline vitals:
• Pulse
• Respirations
•
•
•
•
Blood pressure
Skin
Pupils
Oxygen saturation
Secondary Assessment (4 of 4)
• Vital signs (cont’d)
– Rapid respiratory rate indicates airway
obstruction.
– Rapid respiratory and pulse indicate respiratory
distress or systemic shock.
– Pulse oximetry is a useful method to assess the
patient’s perfusion status.
Reassessment (1 of 3)
• Repeat the primary assessment and
reassess the patient’s vital signs.
– Deterioration of the patient’s condition could be
rapid and fatal.
– Give special attention to any signs of airway
compromise.
– Monitor the patient’s anxiety level.
– Watch for signs of shock.
Reassessment (2 of 3)
• Interventions
– Identify how much distress the patient is in.
– Severe reactions require epinephrine and
ventilatory support.
– Milder reactions require supportive care such as
oxygen.
– Transport to a medical facility.
– Recheck your interventions.
Reassessment (3 of 3)
• Communication and documentation
– When to contact medical control depends on
your assessment findings.
– Documentation should include:
• Signs and symptoms
• Reasons for choosing to provide the care you
did
• Patient’s response to your treatment
Emergency Medical Care (1 of 9)
• If patient appears to be having a severe
allergic (or anaphylactic) reaction:
– Administer BLS, including oxygen.
– Provide prompt transport to the hospital.
– Reassess vital signs every 5 minutes (unstable
patient) or 15 minutes (stable patient).
Emergency Medical Care (2 of 9)
– Place hypotensive or shock patients in the
appropriate position.
– Request ALS backup if you work in a tiered
response system.
– Be prepared to maintain the airway or
administer cardiopulmonary resuscitation.
Emergency Medical Care (3 of 9)
– If a stinger is present, scrape away with a credit
card.
– Applying ice may help.
– In some areas, you may be allowed to
administer epinephrine or assist the patient with
epinephrine administration.
Emergency Medical Care (4 of 9)
• Epinephrine
– Mimics the sympathetic (fight-or-flight) response
– Causes the blood vessels to constrict
– Reverses vasodilation and hypotension
– Increases cardiac contractility and relieves
bronchospasm
– Rapidly reverses the effects of anaphylaxis
Emergency Medical Care (5 of 9)
• Indications include:
– A severe allergic reaction
– Hypersensitivity to an exposed substance
• Remember that your EMS service may or
may not allow you to assist the patient in
the administration of epinephrine. Call
medical control!
Emergency Medical Care (6 of 9)
Source: Courtesy of Shionogi Pharma, Inc.
• All kits should
contain a
prepared,
autoinjectable
syringe of
epinephrine.
Emergency Medical Care (7 of 9)
• The adult EpiPen
delivers 0.3 mg of
epinephrine; the
infant-child system
delivers 0.15 mg.
• The Twinject autoinjector contains two
doses of
epinephrine.
• See Skill Drills 18-1
and 18-2.
Emergency Medical Care (8 of 9)
• Side effects include:
– High blood pressure
– Increased pulse rate
– Anxiety
– Cardiac arrhythmias
– Pallor
– Dizziness
Emergency Medical Care (9 of 9)
• Side effects include (cont’d):
– Chest pain
– Headache
– Nausea
– Vomiting
Summary (1 of 7)
• An allergic reaction is a response to
chemicals the body releases to combat
certain stimuli, called allergens.
• Allergic reactions occur most often in
response to five categories of stimuli: insect
bites and stings, medications, food, plants,
and chemicals.
Summary (2 of 7)
• The reactions may be mild and local,
involving itching, redness, and tenderness,
or they may be severe and systemic,
including shock and respiratory failure.
Summary (3 of 7)
• Anaphylaxis is a life-threatening allergic
reaction mounted by multiple organ
systems, which must be treated with
epinephrine.
• Wheezing and skin wheals can be signs of
anaphylaxis.
Summary (4 of 7)
• People allergic to bee, hornet, yellow jacket,
or wasp venom often carry a kit that
contains epinephrine in an auto-injector.
• All patients with suspected anaphylaxis
require oxygen.
Summary (5 of 7)
• Check patients who may be having an
allergic reaction for flushing, itching, and
swelling skin, hives, wheezing and stridor,
persistent cough, decrease in blood
pressure, weak pulse, dizziness, abdominal
cramps, and headache.
Summary (6 of 7)
• Always provide prompt transport to the
hospital for any patient who is having an
allergic reaction. Remember that signs and
symptoms can rapidly become more
severe.
• Carefully monitor the patient’s vital signs en
route; be especially alert for airway
compromise.
Review
1. The signs and symptoms of an allergic
reaction are caused by the release of:
A. histamine.
B. adrenalin.
C. epinephrine.
D. glucagon.
Review
Answer: A
Response: The two chief chemicals released
by the body that result in the signs and
symptoms of an allergic reaction are
histamines and leukotrienes. Epinephrine
(adrenalin) is used to treat allergic reactions.
Review
2. The negative effects associated with
anaphylactic shock are the result of:
A. severe internal fluid loss.
B. inadequate pumping of the heart.
C. vasodilation and bronchoconstriction.
D. the nervous system’s release of adrenalin.
Review
Answer: C
Rationale: 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 bronchospasm/ bronchoconstriction
and increased mucus production.
Review
3. You are called to a local baseball park for a 23-year-old
man with difficulty breathing. He states that he ate a
package of peanuts approximately 30 minutes ago and
denies any allergies or past medical history. Your
assessment reveals widespread urticaria, tachycardia,
and a BP of 90/60 mm Hg. You can hear him
wheezing, even without a stethoscope. You should be
MOST suspicious of a(n):
A. acute asthma attack.
B. mild allergic reaction.
C. severe allergic reaction.
D. moderate allergic reaction.
Review
Answer: C
Rationale: The patient’s signs and symptoms
indicate a severe allergic reaction, which is
rapidly progressing to anaphylactic shock. Signs
and symptoms of a severe allergic reaction
include difficulty breathing, urticaria (hives) over
large parts of the body, and signs of shock (eg,
tachycardia, hypotension). Certain foods, such as
shellfish and nuts, may result in a relatively slow
onset of symptoms, but the symptoms can
become just as severe.
Review
4. What is a wheal?
A. a raised, swollen, well-defined area on the
skin
B. a poison
C. small areas of generalized itching or burning
that appear as multiple, small, raised areas on
the skin
D. an exaggerated immune response to any
substance
Review
Answer: A
Rationale: Insect stings and bites can cause
a wheal, which is a raised, swollen, welldefined area on the skin. There is no specific
treatment for these injuries, although applying
ice sometimes makes them less irritating.
Review
5. You are treating a woman who was stung
numerous times by hornets. On
assessment, you note that some of the
stingers are still imbedded in her skin. You
should:
A. leave the stingers in place.
B. scrape the stingers from her skin.
C. pull the stingers out with tweezers.
D. cover the stings with tight dressings.
Review
Answer: B
Rationale: Because of the venom left in the
sac located at the end of the stinger, you
should not grab the stingers in an attempt to
remove them. Instead, scrape them off with a
rigid object such as a credit card.
Review
6. A young male is experiencing signs and symptoms of
anaphylactic shock after being stung by a scorpion. His
level of consciousness is diminished, his breathing is
severely labored, you can hear inspiratory stridor, and
his face is cyanotic. The patient has a prescribed
epinephrine auto-injector. What should you do first?
A. Assist him in administering his epinephrine.
B. Apply high-flow oxygen via nonrebreathing mask.
C. Provide ventilatory assistance with a bag-mask
device.
D. Elevate his legs and cover him with a warm
blanket.
Review
Answer: C
Rationale: The patient is not breathing
adequately, as noted by his decreased level of
consciousness, severely labored breathing,
inspiratory stridor, and cyanosis. Therefore, you
should first assist his ventilations with a bag-mask
device. He clearly requires epinephrine, but not
before restoring adequate breathing first.
Regardless of the situation, a patient’s airway
must be patent and his or her breathing must
remain adequate at all times.
Review
7. The MOST reliable indicator of upper
airway swelling during a severe allergic
reaction is:
A. stridor.
B. anxiety.
C. cyanosis.
D. wheezing.
Review
Answer: A
Rationale: Stridor is a high-pitched sound
that is most often heard during inhalation. It
indicates swelling of the upper airway.
Wheezing, a whistling sound, is caused by
narrowed bronchioles; it indicates narrowing
or swelling of the lower airway. Anxiety and
cyanosis can occur from a variety of causes;
they are not exclusive to airway swelling.
Review
8. What is the best tool or method for
assessing a patient’s perfusion status?
A. small-volume nebulizer
B. bag-mask device
C. pulse oximetry
D. auto-injector
Review
Answer: C
Rationale: In a patient experiencing an
allergic reaction, pulse oximetry is a useful
method that you can use to assess the
patient’s perfusion status. By using pulse
oximetry, you can determine the percentage
of oxygen saturation in the bloodstream,
which will assist in identifying the degree of
respiratory distress.
Review
9. The adult EpiPen system delivers
_____ mg of epinephrine, and the
infant-child system delivers _____ mg.
A. 0.15, 0.3
B. 0.3, 0.15
C. 0.15, 0.5
D. 0.5, 0.2
Review
Answer: B
Rationale: The adult EpiPen system delivers
0.3 mg of epinephrine via an automatic needle
and syringe system; the infant-child system
delivers 0.15 mg.
Review
10. When administering epinephrine by autoinjector, the EMT should hold the injector
in place for:
A. 5 seconds.
B. 10 seconds.
C. 20 seconds.
D. 30 seconds.
Review
Answer: B
Rationale: When administering epinephrine
via auto-injector, push the injector firmly
against the thigh until it activates. Hold the
injector in place for 10 seconds to ensure that
all the medication is injected.
Credits
• Background slide images: © Jones & Bartlett
Learning. Courtesy of MIEMSS.