(1) Introduction
This
chapter establishes procedures for recognizing and responding to an
anaphylactic or adverse reaction due to immunization, latex exposure,
food or medication ingestion, or an insect sting.
(2) Overview
(a) Anaphylaxis
is a medical condition encountered by most medical providers during
their career. It is imperative that the provider be able to readily
recognize this condition and render appropriate treatment without
hesitation. Immediate diagnoses and expeditious treatment is very
important.
(b) Risk
factors include:
-
Prior history (radiographic contrast
material, exercise)
-
Multiple antibiotic sensitivity
-
Atopic history (food allergy, latex
allergy, Beta blocker use and possibly ACE inhibitors may increase
the difficulty of treatment.
(c) Clinical
manifestations of anaphylaxis:
-
The onset of anaphylaxis usually
begins within 30 minutes after exposure to a causative factor,
although the onset may be delayed for several hours.
-
Once underway, the reaction usually
progresses in an explosive manner, reaching peak intensity within 1
hour.
-
The primary anaphylactic shock organs
are the cutaneous, gastrointestinal, respiratory, and cardiovascular
systems.
-
Respiratory and cardiovascular events
account for a majority of the mortality associated with anaphylaxis.
-
Typical allergic symptoms.
(1) Generalized
itching or burning (especially on palms, soles, or groin area).
(2) Sneezing
or coughing.
(3) Watering
and itching of the eyes.
(4) Hives
or wheals.
(1) Apprehension
and flushing (especially around the face).
(2) Tightness
in chest or difficulty breathing.
(3) Wheezing
or shortness of breath.
(4) Rapid,
weak pulse. Low blood pressure. Shock.
(5) Cyanosis.
(d) At
the first sign of an anaphylactic reaction, obtain vital signs and the
anaphylaxis treatment kit or Advanced Cardiac Life Support (ACLS)
cart. If the patient has progressive or severe symptoms such as
diffuse hives, wheezing, airway obstruction, hypotension (systolic BP
less than 90), or shock, use protocol (3) immediately.
(3) Protocol
Procedures
(a) Assess
rapidly. Alert
emergency personnel.
(b) Place
patient in a recumbent or trendelenburg position.
(c) Place a tourniquet above injection/sting
site(s) to delay absorption of the antigen. Release the tourniquet
for 1 to 2 minutes, every 10 minutes.
(d) Establish
an airway and provide supplemental oxygen. Inject epinephrine (1:1000)
0.01 ml/kg (max. 0.3 to 0.5 cc) subcutaneously opposite the site of
injection every 20 minutes x 3. If asthma or wheezing is present, use
0.5 cc. Some have advocated injection of 0.1 to 0.2 cc of
epinephrine into the site of the inoculation or sting. Do not
consider this procedure if the allergic response site is on the head,
neck, hands, or feet. Prompt recognition of anaphylaxis and use of
epinephrine is critical. Epinephrine treatment delay can lead to the
risk of fatality.
For pediatric patients administer
epinephrine according to weight as follows:
10 lbs ‑
0.05cc |
30 lbs ‑
0.14cc |
50 lbs ‑
0.23cc |
15 lbs ‑
0.07cc |
35 lbs ‑
0.16cc |
55 lbs ‑
0.25cc |
20 lbs ‑
0.09cc |
40 lbs ‑
0.18cc |
60 lbs ‑
0.27cc |
25 lbs ‑
0.11cc |
45 lbs ‑
0.20cc |
65 lbs ‑
0.30cc |
Continuously monitor vital signs, maintain an open
airway, establish intravenous (IV) access, and attach a cardiac
monitor. Treat for shock if present.
(e) Give IV Ringer's Lactate: 1
to 2 liters (or 20 ml/kg for children.
(f) Give dopamine 2 - 20
mg/kg/min,
only if there is difficulty in maintaining an adequate blood pressure.
[Mix 800 mg in 500 cc D5W to make
solution of 1600
mg/ml.
For a 50 kg patient:
-
5 mg/kg/min
= 9.4 microdrops/min,
-
10 mg/kg/min
= 19 microdrops/min,
-
15 mg/kg/min
= 28 microdrops/min,
-
20 mg/kg/min
= 37.5 microdrops/min.
(g) Other
recommendations as needed include the following:
-
Give Diphenhydramine (Benadryl), 1.25
mg/kg (max. 50 mg) IV over 3 to 5 minutes. THIS IS NOT A SUBSTITUTE
FOR EPINEPHRINE.
-
Give Cimetidine (Tagamet), 5 mg/kg
(maximum 300 mg) IV over 3 to 5 minutes.
-
Give Aminophyline, 5 mg/kg IV over 20
minutes. Then give 0.5 to 1.0 mg/kg/hr for severe bronchospasm, if
blood pressure (BP) and pulse are stable.
(h) Glucagon
(4) Late phase reactions
(a) It
is important to realize that some patients will resolve their
anaphylaxis only to have a spontaneous recurrence 8 to 24 hours later.
-
Bronchodialators prevent the early
phase, not the late phase.
-
Corticosteroids may prevent the late,
but not the early phase.
-
Cromolyn prevents the early and late
phases.
(b)
Corticosteroids given during the initial phase of anaphylaxis does not
prevent the appearance of recurrent or protracted anaphylaxis.
Steroids may lessen the chances or decrease the intensity of
recurrence, but cannot be relied upon to eliminate this response.
However, in severe reactions, it is reasonable to start steroids early
to modify or perhaps prevent protracted or recurrent symptoms. The
dose for
Methylprednisolone is 2 mg/kg, followed
by 1 mg/kg every 6 hours.
(c) Individuals
who have experienced an anaphylactic episode require 12 to 24 hours of
observation.
(d) All
persons with known or suspected anaphylactic episodes require a
careful history and clinical evaluation in consultation with Internal
Medicine or Allergy. Patients should carry epinephrine and Medic
Alert identification.
Submitted by CAPT Jay R. Montgomery,
MC, USN, MED-22, Surface Warfare Medicine, BUMED, Washington, D.C.
(1999). Revised by CAPT J.E. Murnane III, MC, USN, Allergy/Immunology
Specialty Leader, Allergy/Immunology Clinic, Naval Medical Center
Portsmouth, Portsmouth, VA (1999).
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