Anaphylaxis.pdf

ANAPHYLAXIS
PRESENTED BY
CHITRA GAYEN
FINAL YEAR NPCC.

INTRODUCTION
Anaphylaxis is a severe, systemic hypersensitivity reaction that is rapid in onset and
characterized by life-threatening airway, breathing, and/or circulatory problems, and that is
usually associated with skin and mucosal changes.
It is multisystem allergic reaction resulting from the release of a plethora of mediators from
mast cells culminating in serious respiratory, cardiovascular and mucocutaneous manifestations
that can be fatal.
Medications, foods, latex, exercise, hormones (progesterone), and clonal mast cell disorders
may be responsible.

DEFINITION
An acute clinical syndrome characterized by severe, life threatening, generalized type 1
hypersensitivity reaction, usually caused by exposure to a foreign substance leading to
mast cell degranulation and release of chemical mediators.

Anaphylaxis is highly likely when any one of the following 3 criteria are fulfilled:
CRIITERIA 1
Acute onset of an illness with involvement of the skin, mucosal tissue, or both AND AT LEAST
ONE OF THE FOLLOWING:
a. Respiratory compromise.
b. Circulatory compromise
CRITERIA 2
Two or more of the following that occur acutely after exposure to a likely allergen for that patient:
a. Involvement of the skin-mucosal tissue
b. Respiratory compromise.
c. Circulatory compromised
d. Persistent gastrointestinal (GI) symptoms.

CRITERIA 3
Acutely after exposure to known allergen for that patient, reduced BP defined as low SBP
for age or > 30% decrease in SBP.

PRECIPITATING FACTORS
Enteral ingestion: Drugs (Antibiotics, NSAIDs, Aspirin), Food ;
Parenteral administration: Drugs (Antibiotics, Paralytic agents, Opioids,
Propofol),
Insect bites and stings, Contrast media, Vaccines, Blood products ;
Physical contact: Latex ;
Others: Exercise in cases of FDEIA (Food-dependent exercise-induced
anaphylaxis)

Clinical criteria for diagnosing anaphylaxis
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 dyspnoea, wheeze– bronchospasm, stridor, reduced PEF and
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 dyspnoea, wheeze– bronchospasm, stridor, reduced PEF,
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 known allergen for that patient (minutes to several hours):
a. Infants and children: low systolic BP (age specific) or >30% decrease in systolic BP*
b. Adults: systolic BP of <90 mmHg or >30% decrease from that person's baseline

Differential diagnosis of anaphylaxis
Skin or mucosal
chronic remittent or physical urticaria and angioedema
Respiratory diseases
acute laryngotracheitis • laryngeal, tracheal or bronchial obstruction (eg foreign
substances, intermittent laryngeal obstruction or vocal cord dysfunction) •
status asthmaticus (without involvement of other organs)
Cardiovascular diseases
• vasovagal syncope • pulmonary embolism • myocardial infarction • cardiac arrhythmias •
cardiogenic shock Pharmacological or toxic reactions.

Neuropsychiatric diseases •
Hyperventilation syndrome • anxiety and panic disorder • somatoform disorder (eg
psychogenic dyspnoea) • dissociative disorder and conversion (eg globus hystericus) •
epilepsy • cerebrovascular event • psychoses.
Endocrinological diseases
Hypoglycemia • thyrotoxic crisis • carcinoid syndrome

Molecular Mechanisms in Anaphylaxis:
❏ Immunoglobulin E-Dependent Anaphylaxis
Immunoglobulin E-mediated reactions to common allergens are a well-established cause of
anaphylaxis .
In such reactions, allergens (e.g- Peanut/tree nuts, shellfish, egg protein, soybean, milk,
latex, mammalian meat, antibiotics and other drugs, insect venom, seminal fluid, and
occupational allergens) bind to specific IgE that then activates signaling pathways in mast
cells and basophils expressing the high affinity receptor (FcεRI) for IgE .
This culminates in preformed and newly synthesized mediators from mast cells and
basophils that sets off a sequence of inflammatory events manifesting clinically as
anaphylaxis and leading to shock.

Management Algorithm
Clinical Suspect Patient satisfying any of the 3 criterias (as mentioned above) in presence of a
known trigger or precipitating factor.
Initial Management
(First 1 min) ;
Keep Supine Position (Sitting Position If respiratory distress/nausea/vomiting) ;
Assess Airway, Breathing, Circulation, heart rate, BP & SpO2 ;
Provide O2 @ 10-15 L/min by NRBM (If respiratory distress/shock) ;
Identify and Remove the Allergic Trigger if possible (e.g., insect sting) ;
Administer 1st Dose of IM Epinephrine @ 0.01mg/kg/dose (1mg/ml of 1:1000 dilution) at
anterolateral aspect of thigh ;
Can be repeated at 5 to 10 mins interval as needed.

1 to 5 min
Respiratory Distress ; Sitting Position ; Provide High Flow O2 by HFNC and plan for
intubation ;
If Stridor, 1st nebulized epinephrine @ 0.5 mL/kg ;
If Wheeze, 1st nebulized salbutamol @ 0.15 mg/kg
Hypotension/Poor Perfusion/Loss of Consciousness ; Supine Position ; IV/IO Assess to be
established ;
1st Bolus of NS @ 20 mL/kg by IV/IO Rapid Push Technique.

5 to 10 min
If No Improvement give 2nd Dose of IM Epinephrine ; IV/IO Assess to be Established (If
not done earlier ;
Prepare for Difficult Intubation For Respiratory Distress ;
2nd nebulized epinephrine @ 0.5 mL/kg for Stridor;
2nd nebulized salbutamol @ 0.15 mg/kg for Wheeze
Hypotension/Poor Perfusion/Loss of Consciousness ; 2nd Bolus of NS @ 20ml/kg by
IV/IO Rapid Push Technique ;
Prepare for IV Epinephrine
Alert Pediatric ICU/ Tertiary Care Centre.

10 to 20 min
If no Improvement give 3rd Dose of IM Epinephrine For Respiratory Distress ;
3rd nebulized epinephrine @ 0.5 mL/kg for Stridor;
3rd nebulized salbutamol @ 0.15 mg/kg for Wheeze ;
Proceed for Intubation
Hypotension/Poor Perfusion/Loss of Consciousness ; Start giving IV Epinephrine @ 0.05
mcg/ kg/min with titrate by 0.02 mcg/kg/min up to effect
Transfer to Pediatric ICU/ Tertiary Care Centre

If still no Improvement Suspect Refractory Anaphylaxis ;
● Start IV Norepinephrine Infusion (persistent hypotension) @ 0.05 mcg/kg/min with
titrate by 0.02mcg/kg/min up to effect (Max: 2 mcg/kg/min) ;
● IV Glucagon Bolus (persistent anaphylaxis/patients on beta blockers) @ 20 – 30
mcg/kg/dose (Max: 1 mg) over 5 mins followed by 5 to 15 mcg/min titrated till
achievement of clinical effects.
● Delayed Anaphylaxis may be due to biphasic reaction (1 to 20% cases) which
generally occurs within 1 to 72 hours (mostly within 10 hours) after initial
improvement or protracted variety which is the severe persistent anaphylactic
symptoms for 24 to 36 hours despite aggressive treatment. ;
● Monitoring of vitals (BP, SpO2) along with Respiratory Symptoms (stridor or
wheeze) should be done over minutes during first 30 mins and then hourly for next 24
hour and then 2 hourly for next 48 hour. ;
● Follow up of patients should be done for at least 4 hours after last IM Epinephrine
injection and in severe hospitalized cases for minimum 3 days.

Other interventions
Oxygen
Give high flow oxygen to a patient experiencing anaphylaxis.
Fluid support
Administer intravenous fluids early with first adrenaline dose to patients with
cardiovascular involvement as adrenaline may not be effective without restoring the
circulatory volume. Crystalloids are preferred given in boluses of 10 ml/kg (maximum 500
ml per bolus) for children and 500 ml in adults, repeated as needed. This should be
repeated if lack of response. Fluid support could also be given in severe anaphylaxis with a
respiratory presentation if a second dose of intramuscular adrenaline is required.

H1 and H2 antihistamines
Systemic antihistamines have only been demonstrated to relieve cutaneous symptoms and
a possible effect on non-cutaneous symptoms remains unconfirmed.e.g- cetrizine.
Glucocorticoids
Glucocorticoids are commonly used in anaphylaxis as they are thought to prevent
protracted symptoms and possibly biphasic reactions but there is limited evidence of their
effectiveness and they may be deleterious in children.e.g- pridnisolone.
Inhaled Beta2-Agonists
In the case of predominant bronchial obstruction, inhaled ß-adrenoreceptor agonists, (eg
salbutamol) can be additionally administered.
Inhaled adrenaline
In cases with suspected laryngeal/pharyngeal oedema, inhaled administration of
adrenaline via a nebulizer together with oxygen is recommended.

REFERENCES
1. Antonella Muraro EAACI guidelines: Anaphylaxis (2021 update).
2. Simons FE, Ardusso LR, Bilo MB, et al. International consensus on (ICON)
anaphylaxis. World Allergy Organ J. 2014;7(1):9.
3. P. Dewachter and L. Savic Perioperative anaphylaxis: pathophysiology, clinical
presentation and management,2019 British Journal of Anaesthesia. Published by
Elsevier.
4. Neeraj Gupta STANDARD TREATMENT GUIDELINES 2022 Anaphylaxis Indian
Academy of Pediatrics (IAP).

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