Transcript bledsoe_pcpp4_ch05_lecture - McLaren

Paramedic Care: Principles & Practice
Fourth Edition
Volume 4: Medicine
CHAPTER
5
Immunology
Multimedia Directory
Slide 49
Slide 58
Diphenhydramine Animation
Epinephrine Video
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Standard
• Medicine (Immunology)
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Competency
• Integrates assessment findings with
principles of epidemiology and
pathophysiology to formulate a field
impression and implement a
comprehensive treatment/disposition
plan for a patient with a medical
complaint.
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Paramedic Care: Principles & Practice, 4th Ed.
Introduction
• Allergic reaction: exaggerated response
by immune system to foreign
substance.
– Can range from mild skin rashes to
severe, life-threatening reactions that
involve virtually every body system.
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Paramedic Care: Principles & Practice, 4th Ed.
Introduction
• Anaphylaxis: most severe type of
allergic reaction.
– Anaphylaxis is life-threatening
emergency; advanced life-support
measures often mean difference
between life and death.
 Can develop within seconds and cause
death just minutes after exposure to
offending agent.
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Paramedic Care: Principles & Practice, 4th Ed.
Introduction
• Anaphylaxis: most severe type of
allergic reaction.
– Several emergency medications
available that can reverse adverse
effects.
• Injected penicillin and bee and wasp
stings two most common causes of
fatal anaphylaxis.
– 400 to 800 deaths annually in U.S.
attributed to anaphylaxis.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Principal body system involved in
allergic reactions.
– Responsible for combating infection.
– Components found in blood, bone
marrow, lymphatic system.
– Goal of immune response: destruction
or inactivation of pathogens, abnormal
cells, foreign molecules such as toxins.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Cellular immunity: direct attack of
foreign substance by specialized cells of
immune system.
– Humoral immunity: chemical attack of
invading substance.
– Principal chemical agents of this attack
are antibodies (immunoglobulins [Igs]).
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Antibodies manufactured by specialized
cells of immune system called B cells.
– Five classes of antibodies: IgA, IgD,
IgE, IgG, IgM.
– Humoral immune response begins with
exposure of body to antigen.
– Antigen: any substance capable of
inducing immune response.
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Pathophysiology
• Immune System
– Most antigens are proteins.
– Following exposure to antigen,
antibodies released; attach themselves
to invading substance to facilitate
removal of that substance from body.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Primary response: initial response to
antigen.
 Several days required before both
cellular and humoral components of
immune system respond.
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Pathophysiology
• Immune System
– Secondary response: antibodies specific
for offending antigen released.
 Antigen-specific antibodies more
effective.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Natural immunity (innate immunity):
genetically predetermined; present at
birth; no relation to previous exposure
to particular antigen.
– Acquired immunity: develops over time;
results from exposure to antigen.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Naturally acquired immunity: develops
after birth; enhanced by exposure to
new pathogens and antigens throughout
life.
– Induced active immunity (artificially
acquired immunity): designed to
provide protection from exposure to
antigen at some time in future.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Induced active immunity: achieved
through vaccination; provides protection
against serious infectious agents.
– In vaccination, antigen injected into
body to generate immune response.
– Development of antibodies specific for
antigen; provides protection against
future infection.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Most vaccines contain antigenic proteins
from particular virus or bacterium.
 Example: DPT
(diphtheria/pertussis/tetanus) vaccine
– Some vaccinations will impart lifelong
immunity; others periodically followed
with “booster dose.”
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Acquired immunity is active or passive.
– Active immunity: occurs following
exposure to antigen; results in
production of antibodies specific for
antigen.
– Most vaccinations result in development
of active immunity.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Immune System
– Passive immunity: administration of
antibodies.
– Natural passive immunity: antibodies
cross placental barrier from mother to
infant to provide protection against
embryonic or fetal infections.
– Induced passive immunity:
administration of antibodies to help fight
infection or prevent diseases.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Sensitization: initial exposure of
individual to antigen; results in immune
response.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Hypersensitivity: unexpected and
exaggerated reaction to particular
antigen (allergy).
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Delayed hypersensitivity: result of
cellular immunity; does not involve
antibodies; occurs hours and days
following exposure.
– Immediate hypersensitivity: allergy;
immediate reactions: hay fever, drug
allergies, food allergies, eczema,
asthma.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Allergen: antigen that causes release of
IgE antibodies.
 Drugs
 Foods and food additives
 Animals
 Insects and insect parts
 Fungi and molds
 Radiology contrast materials
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Paramedic Care: Principles & Practice, 4th Ed.
Anaphylactic reactions can result from a variety of causes.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Allergens enter body through: oral
ingestion, inhalation, topically, injection,
or envenomation.
– Majority of anaphylactic reactions result
from injection or envenomation.
– Parenteral penicillin injections most
common cause of fatal anaphylactic
reactions.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Insect stings second most frequent
cause of fatal anaphylactic reactions.
 Fire ants, wasps, yellow jackets, hornets,
honeybees
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Following exposure to particular
allergen, large quantities of IgE
antibodies released; attach to
membranes of basophils and mast cells.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– These cells release histamine, heparin,
other substances; process of releasing
called degranulation.
– This release results in allergic reaction;
can be mild to severe.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Allergies
– Principal chemical mediator of allergic
reaction is histamine; minimizes body's
exposure to antigen.
– Histamine: potent substance; causes
bronchoconstriction, increased intestinal
motility, vasodilation, increased vascular
permeability.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Anaphylaxis
– Occurs when specific allergen injected
directly into circulation.
– When allergen enters circulation, it is
distributed widely throughout body.
– Principal body systems affected by
anaphylaxis: cardiovascular,
respiratory, gastrointestinal systems;
the skin.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Anaphylaxis
– Histamine causes widespread peripheral
vasodilation.
– Increased permeability of capillaries
results in marked loss of plasma from
circulation.
– People sustaining anaphylaxis can
actually die from circulatory shock.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology
• Anaphylaxis
– Released from basophils and mast cells
is slow-reacting substance of
anaphylaxis (SRS-A).
 Results in asthmalike attack;
occasionally, asphyxia.
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Paramedic Care: Principles & Practice, 4th Ed.
Pathophysiology of anaphylaxis.
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Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in
Anaphylaxis
• Signs and symptoms begin within 30–
60 seconds following exposure to
offending allergen.
– Severity often related to speed of onset.
– Reactions that develop very quickly tend
to be much more severe.
• Rapid and focused assessment crucial.
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Assessment Findings in
Anaphylaxis
• Patients with sense of impending doom
often followed by development of
additional signs and symptoms.
• If possible, brief history should be
gathered, including previous allergen
exposures and reactions.
• Quickly evaluate level of consciousness.
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Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in
Anaphylaxis
• Common manifestation is angioneurotic
edema, involving face and neck.
– Laryngeal edema frequent complication
and can threaten the airway.
– May lead to complete airway obstruction
from either massive laryngeal edema,
laryngospasm, pharyngeal edema, or
combination of any of these.
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Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in
Anaphylaxis
• Respiratory system significantly
involved in anaphylactic reaction.
– Tachypneic; lower airway edema and
bronchospasm; respirations become
labored; wheezing; markedly diminished
lung sounds.
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Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in
Anaphylaxis
• Fine red rash appears diffusely on skin.
• Urticaria (hives): wheal and flare
reaction characterized by red, raised
bumps.
• As cardiovascular collapse and dyspnea
progress, patient will become
diaphoretic; if untreated, will progress
to cyanosis and pallor.
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Hives are red, itchy blotches, sometimes raised, that often accompany an allergic reaction. (© Charles Stewart,
MD, MPH)
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in
Anaphylaxis
• Effect of histamine on gastrointestinal
system pronounced.
– Nausea, vomiting, diarrhea develop.
• Vital signs vary depending on severity
and stage of severe allergic or
anaphylactic reaction.
– Respiratory rate and heart rate can fall;
ominous findings.
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Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in
Anaphylaxis
• Monitoring devices: cardiac monitor,
pulse oximeter; if patient intubated,
end-tidal carbon dioxide detector.
• End-tidal carbon dioxide level may
climb due to development of both
respiratory and metabolic acidosis.
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Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Ensure scene safe; chemicals or
patrolling bees can pose risk.
• Honeybees often leave stinger behind;
if present, remove by scraping skin
with fingernail or scalpel blade.
• Always consider possibility of trauma;
signs and symptoms of trauma may be
masked by signs and symptoms of
anaphylaxis.
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Paramedic Care: Principles & Practice, 4th Ed.
Management of anaphylaxis and allergic reactions.
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Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• If suspicion of coincidental trauma,
stabilize cervical spine.
• Position patient and protect airway.
• Administer oxygen via nonrebreather
mask.
• If patient hypoventilating or apneic,
initiate ventilatory assistance.
• First apply basic airway maneuvers.
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Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Use oropharyngeal and nasopharyngeal
airways with caution; can cause
laryngospasm
• If patient having severe airway
problems, consider early endotracheal
intubation to prevent complete
occlusion of airway.
• Have equipment available for
placement of surgical airway.
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Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Establish IV as soon as possible with a
crystalloid solution.
• If patient hypotensive, administer fluids
wide open.
• If time allows, place second IV line.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Administer Medications
– Primary treatment for anaphylaxis is
pharmacological.
– Oxygen always first drug to administer
with anaphylactic reaction.
– Epinephrine primary drug for use in
treatment of severe allergic reactions
and anaphylaxis; sympathetic agonist.
 Acts within minutes of administration.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Administer Medications
– Antihistamines second-line agents in
treatment of anaphylaxis; given only
following administration of epinephrine.
 Block effects of histamine by blocking
histamine receptors.
 Diphenhydramine (Benadryl): most
frequently used antihistamine in
treatment of allergic reactions and
anaphylaxis.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Diphenhydramine Animation
Click here to view an animation on the topic of diphenhydramine.
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©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Administer Medications
– Corticosteroids: important in treatment
and prevention of anaphylaxis; help
suppress inflammatory response.
– Vasopressors: severe and prolonged
anaphylactic reactions may require
potent vasopressors to support blood
pressure.
 Dopamine, norepinephrine, epinephrine
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Administer Medications
– Beta-agonists: severe allergic reactions
and anaphylaxis will develop
bronchospasm, laryngeal edema, or
both.
 Prehospital care: albuterol (Ventolin,
Proventil).
 Reverse some of bronchospasm and
laryngeal edema associated with
anaphylaxis.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Management of Anaphylaxis
• Administer Medications
– Other Agents: vasopressin, atropine,
glucagon.
– Provide patient emotional support and
explain treatment regimen.
– Caution patients about potential side
effects of administered medications.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Assessment Findings in Allergic
Reaction
• Allergic reaction will have more gradual
onset with milder signs and symptoms.
• Patient will have normal mental status.
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Paramedic Care: Principles & Practice, 4th Ed.
Management of Allergic Reactions
• Mild (nonanaphylactic) allergic
reactions: itching, rash, urticaria.
– Simple itching and nonurticarial rashes
treated with antihistamines alone.
– In addition to antihistamines,
epinephrine often necessary for
treatment of urticaria.
• If exhibits dyspnea or wheezing, should
receive supplemental oxygen.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Management of Allergic Reactions
• Lesser allergic reactions not
accompanied by hypotension or airway
problems treated with epinephrine
1:1,000 administered intramuscularly.
– Intramuscular route should not be used
in severe anaphylaxis; IV epinephrine
should be administered.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Patient Education
• Many severe allergic and anaphylactic
reactions preventable.
• Persons with history of anaphylactic
reactions should be educated about
recognition and treatment.
• They should wear identification device,
such as Medic-Alert bracelet; alerts
paramedics to condition if they are
unresponsive.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Patient Education
• Many patients initiate emergency
anaphylactic treatment at home with
epinephrine delivery systems (EpiPen).
• Severity of allergic reaction can be
diminished in certain cases through
process called desensitization.
– Quantity of allergen in injection
gradually increased to point where
anaphylactic reactions are averted.
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Paramedic Care: Principles & Practice, 4th Ed.
Epinephrine Video
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Patient Education
• Paramedics often keep reference cards
for anaphylactic patients living in their
service area.
– Quickly identify them, their allergy,
prehospital treatment history.
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Paramedic Care: Principles & Practice, 4th Ed.
Summary
• Severe allergies and anaphylaxis
uncommon.
• When they do occur, they can progress
quickly and result in death in minutes.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Summary
• Central physiologic action in
anaphylaxis is massive release of
histamine and other mediators.
• Histamine causes bronchospasm,
airway edema, peripheral vasodilation,
and increased capillary permeability.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Summary
• Primary, and most important, drug
used in treatment of anaphylaxis is
epinephrine.
• Epinephrine helps reverse effects of
histamine.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Summary
• Epinephrine also supports blood
pressure and reverses detrimental
capillary leakage.
• Following administration of epinephrine,
potent antihistamines should be used
to block adverse effects of massive
histamine release.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Summary
• Inhaled beta-agonists useful in severe
bronchospasm and airway involvement.
• Intravenous fluid replacement crucial in
preventing hypovolemia and
hypotension.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.
Summary
• Key to successful prehospital
management of anaphylaxis is prompt
recognition and treatment.
©2013 Pearson Education, Inc.
Paramedic Care: Principles & Practice, 4th Ed.