Anaphylactic shock is caused by a severe allergic reaction when a
patient who has already produced antibodies to a foreign sub-stance (antigen)
develops a systemic antigen–antibody reaction. This process requires that the
patient has previously been exposed to the substance. An antigen–antibody
reaction provokes mast cells to release potent vasoactive substances, such as
histamine or bradykinin, that cause widespread vasodilation and capillary
per-meability. Anaphylactic shock occurs rapidly and is life-threatening.
Because anaphylactic shock occurs in patients already exposed to an antigen who
have developed antibodies to it, it can often be prevented. Therefore, patients
with known allergies need to understand the consequences of subsequent exposure
to the anti-gen and should wear medical identification that lists their
sen-sitivities. This could prevent inadvertent administration of a medication
that would lead to anaphylactic shock. Additionally, the patient and family
need instruction about emergency use of medications to treat anaphylaxis.
Treatment of anaphylactic shock requires removing the causative antigen
(eg, discontinuing an antibiotic agent), administering medications that restore
vascular tone, and providing emergency support of basic life functions.
Epinephrine is given for its vaso-constrictive action. Diphenhydramine
(Benadryl) is administered to reverse the effects of histamine, thereby
reducing capillary per-meability. These medications are given intravenously.
Nebulized medications, such as albuterol (Proventil), may be given to re-verse
If cardiac arrest and
respiratory arrest are imminent or have occurred, cardiopulmonary resuscitation
is performed. Endotra-cheal intubation or tracheotomy may be necessary to
establish an airway. Intravenous lines are inserted to provide access for
ad-ministering fluids and medications.
The nurse has an important role in preventing anaphylactic shock:
assessing all patients for allergies or previous reactions to antigens (eg,
medications, blood products, foods, contrast agents, latex) and communicating
the existence of these allergies or reac-tions to others. Additionally, the
nurse assesses the patient’s un-derstanding of previous reactions and steps
taken by the patient and family to prevent further exposure to antigens. When
new allergies are identified, the nurse advises the patient to wear or carry
identification that names the specific allergen or antigen.When administering
any new medication, the nurse observes the patient for an allergic reaction.
This is especially important with intravenous medications. Allergy to
penicillin is one of the most common causes of anaphylactic shock. Patients who
have a penicillin allergy may also develop an allergy to similar medica-tions.
For example, they may react to cefazolin sodium (Ancef ) because it has a
similar antimicrobial action of attaching to the penicillin-binding proteins
found on the walls of infectious or-ganisms. Previous adverse drug reactions
increase the risk that an elderly patient will develop an undesirable reaction
to a new med-ication. If the elderly patient reports an allergy to a medication,
the nurse must be aware of the risks involved in the administra-tion of similar
In the hospital and outpatient diagnostic testing sites, the nurse must
identify patients at risk for anaphylactic reactions to contrast agents
(radiopaque, dye-like substances that may contain iodine) used for diagnostic
tests. These include patients with a known allergy to iodine or fish or those
who have had previous allergic reactions to contrast agents. This information
must be conveyed to the staff at the diagnostic testing site, including x-ray
The nurse must be
knowledgeable about the clinical signs of anaphylaxis, must take immediate
action if signs and symptoms occur, and must be prepared to begin
cardiopulmonary resusci-tation if cardiorespiratory arrest occurs. In addition
to monitor-ing the patient’s response to treatment, the nurse assists with
intubation if needed, monitors the hemodynamic status, ensures intravenous
access for administration of medications, administers prescribed medications
and fluids, and documents treatments and their effects.
Community health and
home care nurses whose role includes administering medications, including
antibiotic agents, in the patient’s home or other settings must be prepared to
administer epinephrine subcutaneously or intramuscularly in the event of an
After recovery from anaphylaxis, the patient and family require an
explanation of the event. Further, the nurse provides instruc-tion about
avoiding future exposure to antigens and administering emergency medications to