2. Objectives
• What is anaphylaxis ?
• How does it presents ?
• How to diagnose it ?
• How to manage it ?
3. Introduction
• In industrialized countries, the estimated lifetime prevalence of anaphylaxis from
all causes is between 0.05 and 2 percent in the general population, and the rate of
occurrence is increasing.
• Anaphylaxis is a systemic reaction that could be mediated by immunologic as well
as non-immunologic mechanisms.
• It most often results from immunoglobulin E (IgE)-mediated reactions to foods,
drugs, and insect stings, but any agent capable of inciting a sudden, systemic
degranulation of mast cells can induce it.
• Diagnosis is clinical and laboratory evaluation is rarely required.
4.
5. What is Anaphylaxis ?
• Anaphylaxis is a serious systemic hypercreativity reaction that is usually rapid in onset
and may cause death.
• Severe anaphylaxis is charactered by potentially life-threatening compromise in airway,
breathing and/or the circulation, and may occur without typical skin features or
circulatory shock being present. (World Health Organization International Classification of
Diseases 11th Edition)
• Anaphylaxis is a clinical diagnosis that can present with any combination of symptoms
affecting various organ systems.
• The clinical presentation and severity of symptoms differ among individuals and may
change over time within the same individual.
13. • Second exposure
Activation of mast cell to release histamine and
other mediators
Allergen
Mediators
Mast cell
FcɛRI
IgE
14.
15. What are the Symptoms of
Anaphylaxis ?
• Cutaneous/mucosal (80% to
90%)
• Respiratory (70%)
• Gastrointestinal (45%)
• Circulatory (45%)
16.
17.
18. How to diagnose it ?
• Anaphylaxis is highly likely when any ONE of the following three
criteria is fulfilled:
1. Acute onset of an illness (minutes to several hours) with
involvement of the skin, mucosal tissue, or both (eg, generalized
hives, pruritus or flushing, swollen lips-tongue-uvula)
AND AT LEAST ONE OF THE FOLLOWING:
A. Respiratory compromise (eg, dyspnea, wheeze-bronchospasm,
stridor, hypoxemia)
B. Reduced BP* or associated symptoms of end-organ dysfunction
(eg, hypotonia, collapse, syncope, incontinence)
2. TWO OR MORE OF THE FOLLOWING that
occur rapidly after exposure to a LIKELY
allergen for that patient (minutes to several
hours):
A. Involvement of the skin mucosal tissue (eg,
generalized hives, itch-flush, swollen lips-
tongue-uvula)
B. Respiratory compromise (eg, dyspnea,
wheeze-bronchospasm, stridor, hypoxemia)
C. Reduced BP* or associated symptoms (eg,
hypotonia, collapse, syncope, incontinence)
D. Persistent gastrointestinal symptoms (eg,
crampy abdominal pain, vomiting)
3. Reduced BP* after exposure to a KNOWN allergen for that
patient (minutes to several hours):
A. Infants and children - Low systolic BP (age-specific)* or greater
than 30% decrease in systolic BP
B. Adults - Systolic BP of less than 90 mmHg or greater than 30%
decrease from that person's baseline
19.
20. o Anaphylaxis is a clinical diagnosis, and treatment
cannot await laboratory confirmation. When the cause
of the observed symptoms is in doubt, treatment for
anaphylaxis is initiated. The clinical diagnosis can
sometimes be retrospectively supported by
documentation of elevated concentrations of serum or
plasma total tryptase or plasma histamine, although the
results of these tests are not immediately available to
the treating clinician.
o It is critical to obtain blood samples for measurement
of these mast cell and basophil mediators soon after
the onset of symptoms because elevations are
transient.
21. • Temporal patterns —
• Anaphylaxis is usually characterized by a defined exposure to a potential cause, followed usually within seconds to minutes but
rarely up to hours later, by rapid onset, evolution, and ultimate resolution of symptoms and signs.
• Uniphasic anaphylaxis —
• Uniphasic anaphylactic reactions are the most common type, accounting for an estimated 80 to 94 percent of all episodes. A
uniphasic response typically peaks within hours after symptom onset and then either resolves spontaneously or after treatment,
usually within several hours
• Biphasic anaphylaxis —
• Biphasic anaphylaxis is defined as a recurrence of symptoms meeting anaphylaxis diagnostic criteria that develops within 1 to 48
hours following the apparent resolution of the initial anaphylactic episode with no additional exposure to the causative agent
• occur in about 5 percent of cases.
• Recurrent symptoms typically occur within 12 hours after resolution of the initial symptoms.
• Protracted anaphylaxis —
• A protracted or persistent anaphylactic reaction lasts hours to days without clearly resolving completely. .
• Refractory anaphylaxis —
• the persistence of anaphylaxis following appropriate epinephrine dosing with three or more appropriate doses of epinephrine or
initiation of an intravenous epinephrine infusion along with symptom-directed medical management (eg, intravenous fluids for
hypotension).
• Delayed anaphylaxis —
• The onset of anaphylaxis can be delayed (ie, beginning hours rather than minutes after exposure to the causative agent) as can be
observed in cases of alpha-gal syndrome, an increasingly recognized food allergy
22. How to manage it ?
• Acute management: in a hospital setting.
• The first and most important therapy in anaphylaxis is epinephrine. There
are NO absolute contraindications to epinephrine in the setting of
anaphylaxis.
• Airway – Immediate intubation if evidence of impending airway
obstruction from angioedema.
• Delay may lead to complete obstruction. Intubation can be difficult and should be
performed by the most experienced clinician available. Cricothyrotomy may be
necessary.
23. • IM epinephrine (1 mg/mL preparation)
• Epinephrine 0.01 mg/kg should be injected IM in the mid-outer thigh.
• For large children (>50 kg), the maximum is 0.5 mg per dose. If there is no
response or the response is inadequate, the injection can be repeated in 5
to 15 minutes (or more frequently). If epinephrine is injected promptly IM,
patients respond to 1, 2, or, at most, 3 injections.
• If signs of poor perfusion are present or symptoms are not responding to
epinephrine injections, prepare IV epinephrine for infusion.
24. • For pediatric patients, administration of epinephrine into the anterolateral thigh is
preferred to the deltoid region as this likely decreases the risk for inadvertent intraosseous
administration due to needle length.
• Intra- venous administration of epinephrine is also not recommended as first-line
treatment of acute anaphylaxis, even in a medical setting, due to risk for cardiac adverse
events such as arrhythmias and myocardial infarction
• However, for patients with inadequate response to intramuscular epinephrine and intrave-
nous saline, intravenous epinephrine can be given by continuous infusion by microdrip,
preferably using an infusion pump in a monitored hospital setting.
25. • Place patient in recumbent position, if
tolerated, and elevate lower extremities.
• Oxygen – Give 8 to 10 L/minute via facemask
or up to 100% oxygen, as needed.
• Normal saline rapid bolus – Treat poor
perfusion with rapid infusion of 20 mL/kg.
• Reevaluate and repeat fluid boluses (20
mL/kg), as needed. Massive fluid shifts with
severe loss of intravascular volume can
occur. Monitor urine output.
• Albuterol – For bronchospasm resistant to IM
epinephrine,
• give albuterol 2.5 mg inhaled via nebulizer.
Dilute in saline if using a concentrated
albuterol solution (≥0.5%). Repeat, as
needed.
• H1 antihistamine – Consider giving
diphenhydramine 1 mg/kg (maximum 50 mg IV,
over 5 minutes) or cetirizine (children aged 6
months to 5 years can receive 2.5 mg IV, those
6 to 11 years of age can receive 5 or 10 mg IV,
over 2 minutes).
• H2 antihistamine – Consider giving famotidine
0.25 mg/kg (maximum 20 mg) IV, over at least 2
minutes.
• Glucocorticoid – Consider giving
methylprednisolone 1 mg/kg (maximum 125
mg) IV.
• Monitoring – Continuous noninvasive
hemodynamic monitoring and pulse oximetry
monitoring should be performed.
• Urine output should be monitored in
patients receiving IV fluid resuscitation for
severe hypotension or shock.
26. • Glucocorticosteroids are commonly used in anaphylaxis, with the objective
of preventing protracted symptoms, in particular in patients with asthmatic
symptoms, and also to prevent biphasic reactions (eg, intravenous
hydrocortisone, or methylprednisolone).
• However, there is increasing evidence that glucocorticosteroids may be of
no benefit in the acute management of anaphylaxis, and may even be
harmful; their routine use is becoming controversial.
27. • Epinephrine infusion – In patients with inadequate response to IM
epinephrine and IV saline, give epinephrine continuous infusion at 0.1 to 1
microgram/kg/minute, titrated to effect.
• Vasopressors – Patients may require large amounts of IV crystalloid to
maintain blood pressure. Some patients may require a second vasopressor (in
addition to epinephrine). All vasopressors should be given by infusion pump,
with the doses titrated continuously according to blood pressure and cardiac
rate/function monitored continuously and oxygenation monitored by pulse
oximetry.
• Glucagon – Patients on beta blockers may not respond to epinephrine and can
be given glucagon 20 to 30 micrograms/kg (maximum 1 mg) IV over 5
minutes. Rapid administration of glucagon can cause vomiting.
Treatment of refractory symptoms:
28. Disposition
• Observation
• 2 to 6 hours of is safe for children treated for anaphylaxis without complications.
• Admission:
• patients who do not respond promptly to intramuscular (IM) epinephrine,
• require more than one dose of epinephrine,.
• received epinephrine only after a significant delay (>60 minutes) as these features may be risk factors for a
biphasic response
• Discharge care — All patients who have experienced anaphylaxis should be sent home with the following:
• An anaphylaxis emergency action plan
• At least one epinephrine autoinjector in hand or a prescription for two epinephrine autoinjectors and instructions
to fill the prescription immediately
• Printed information about anaphylaxis and its treatment
• (Documented) advice to follow up to an allergist, with a referral if possible
35. References
• UpToDate
• Anaphylaxis—a 2020 practice parameter update, systematic
review, and Grading of Recommendations, Assessment,
Development and Evaluation (GRADE) analysis.
• Netter’s Pediatrics.
