Treating Anaphylaxix

Research Paper Paramedic Procedures I - Fall 1996 11/3/96

In the emergency setting, anaphylaxis is a dangerous, life threatening condition
that must be treated in an aggressive and timely fashion. Anaphylaxis is a
condition related to acute allergic reactions. Following the body\'s exposure to
the offending allergen, there are common systemic reactions. The most serious
reactions involve the respiratory and cardiovascular systems, but the
gastrointestinal, dermatologic, and genitourinary systems are often involved
causing varied symptoms such as urticaria, flushing, angioedema, bronchospasm,
hypotension, cardiac arrythmias, nausea, intestinal cramps, pruritus, and
finally uterine cramps. (Physician Assistant, 8/94) The above list is by no
means exhaustive, specific symptoms vary from person to person. The same person
suffering from several anaphylactic reactions can also present with differing

Physiologically speaking, the two main effects of the body\'s released mediators
(IgE) during an anaphylactic reaction are smooth muscle contraction and
vasodilatation, which cause most of the body\'s adverse symptoms. (JAMA,
11/26/82) Since the most life threatening reactions usually involve the
respiratory and cardiovascular systems, that is where emergency treatment is
focused. In the cardiovascular system, a combination of vasodilatation,
increased vascular permeability, tachcycardia, and arrhythmias can lead to
severe hypotension. In the respiratory system, the swelling of tissues along
with bronchospasm and increased mucus production are the main cause of death.
So, if untreated, anaphylaxis can be fatal as a result of the body\'s going into
what is essentially shock, while simultaneously (and more importantly) being
deprived of the oxygen needed to sustain life.

As of today there is one universally accepted treatment for acute anaphylaxis.
Epinephrine. Epinephrine is both an alpha and a beta agonist. This makes it
the drug optimally suited to treat anaphylaxis. "Epinephrine will increase
vascular resistance, reduce vascular permeability, produce bronchodilation and
increase cardiac output." (Emergency, 10/93)

Epinephrine will directly counteract the potentially life threatening aspects of
anaphylaxis. Epinephrine can , and is, used in the both the pre-hospital
environment as well as in definitive care institutions. Epinephrine is widely
administered by ALS providers the world over. The drug is so effective that and
relatively simple to use that "…subcutaneous administration of epinephrine by
EMT-B\'s trained in recognition … of anaphylaxis… is safe." (Annals of
Emergency Medicine, 6/95)

Following the administration of epinephrine, antihistamines such as
diphenhydramine, hydroxyzine, and promethazine can be administered. These
agents block the harmful effects of histamine, a mediator associated with
allergic reactions, and while not displacing histamine from receptors, they
compete with histamine for receptor cites and therefore block additional
histamine from binding. (JEMS, 4/95)

Patients taking beta adrenergic blocking agents will have limited benefits from
the administration of epinephrine (it being a beta agent), as well potentially
unopposed alpha adrenergic effects that could result in severe hypertension.
(Physician Assistant, 8/94) In such cases norepinepherine and dopamine may be
necessary to treat systemic anaphylaxis. Glucagon which increases cAMP, is a
bronchodilator, and stimulates cardiac output, can be very useful, even in the
presence of beta blockers. (Physician Assistant, 8/94)

Inhaled bronchodilators are useful for the treatment of respiratory
complications associated with anaphylaxis. There is a wide variety of
acceptable agents. Sympathomimetics such as albuterol, and metaproterenol will
relax the smooth muscle in the respiratory tract. Anticholinergic agents such
as ipratropium bromide can also decrease bronchospasm. Aminophylline, a
bronchodilator and diuretic can also increase intracellular cAMP levels, as well
as potentiating catecholamines and stimulating their release; these effects
make it a useful tool in dealing with persistent bronchospasm. (Physician
Assistant, 8/94)

Even though steroids (glucocorticosteroids) have some potentially beneficial
effects for the relief of bronchospasm and hypotension, they are not recommended
for the treatment of acute anaphylactic symptoms due to the fact that it takes
four to six hours for them to be effective. (JAMA, 11/26/82) But, steroids
such as methylprednisolone and hydrocortisone, are useful in shortening the
duration of, and reducing the severity of prolonged anaphylactic reactions, as
well as preventing the recurrence of delayed symptoms. (Physician Assistant,

The above agents are all widely used to treat anaphylaxis. But there are
studies and experiments underway that are looking at alternative, or additional
treatments. Naloxone and thyrotropin-releasing hormone (TRH) are both being
looked at in the possible treatment of anaphylaxis as well as traumatic shock.
"Naloxone improves cardiovascular function in a variety of animal models of
shock caused by…and anaphylaxis. Administration of TRH …also has pressor
effects in these shock models." (Annals of Emergency Medicine, 8/85)

"TRH has been shown to increase mean arterial pressure during anaphylactic
shock." (Annals of Emergency Medicine, 5/89) In animal studies of anaphylaxis
the use of TRH, epinephrine, and normal saline were compared. TRH treated
rabbits responded slightly better than those treated with epinephrine (the study
focused on cardiovascular and respiratory parameters.) (Annals of Emergency
Medicine, 5/89)

I started this project with