Approach to a child presenting with anaphylaxis

Algorithm

graph TD

classDef start fill:#1b5e20,color:#ffffff,stroke:#66bb6a;
classDef step fill:#0d47a1,color:#ffffff,stroke:#42a5f5;
classDef decision fill:#4a148c,color:#ffffff,stroke:#ab47bc;
classDef alert fill:#b71c1c,color:#ffffff,stroke:#ef5350;

A(<b>Start Triage</b><br>Rapid Assess ABCDE):::start
B[<b>Immediate Interventions</b><br>Trendelenburg and Bedside Glucose]:::step
C{<b>First Line Therapy</b><br>Do Not Delay}:::decision
D[<b>Epinephrine IM</b><br>0.01 mg per kg max 0.5 mg]:::alert
E{<b>Parallel Support</b><br>Targeted System Management}:::decision
F1[<b>Airway and Breathing</b><br>100 Oxygen and Intubation Prep]:::step
F2[<b>Hemodynamics</b><br>IV IO Fluid Bolus 20 mL per kg]:::step
F3[<b>Source and Symptoms</b><br>Remove Trigger and Nebulized Salbutamol]:::step
G{<b>Reassessment</b><br>Every 5 to 15 Minutes}:::decision
H1[<b>Clinical Improvement</b><br>Adjunct Antihistamines and Steroids]:::step
H2[<b>Refractory Shock</b><br>Continuous IV Epi Infusion]:::alert
I(<b>Disposition</b><br>PICU Admission):::start

A --> B
B --> C
C --> D
D --> E
E --> F1
E --> F2
E --> F3
F1 --> G
F2 --> G
F3 --> G
G -->|Persistent Symptoms| D
G -->|Responsive| H1
G -->|Refractory| H2
H1 --> I
H2 --> I

Pathophysiology And Etiology

Fundamental Mechanisms

• Represents catastrophic systemic hypersensitivity reaction.
• Characterized by acute multiorgan system dysfunction.
• Progresses rapidly to life-threatening cardiopulmonary compromise.
• Involves massive acute release of chemical mediators.
• Mediators include histamine, leukotrienes, and bradykinin.
• Originates from degranulating mast cells and basophils.

Triggering Agents

• Requires prior sensitization in susceptible individuals.
• Commonly triggered by insect bites and stings.
• Frequently associated with specific food ingestions.
• Provoked by specific medications and environmental agents.

Hemodynamic Alterations

• Induces classic distributive shock pattern hemodynamically.
• Sudden histamine release causes profound peripheral vasodilation.
• Promotes severe increase in capillary permeability.
• Drastically reduces systemic vascular resistance.
• Causes sudden fall in both preload and afterload.
• Maldistributes blood flow away from vital end-organs.
• Causes severe intravascular volume depletion via capillary leak and third-spacing.
• Triggers compensatory marked increase in heart rate and cardiac output initially.

Clinical Manifestations And Recognition

Presentation Characteristics

• Exhibits sudden catastrophic onset.
• Lacks classical prodromal phase.
• Diagnosis heavily relies on circumstantial history including specific ingestions or stings.
• Manifests via specific multiorgan clinical constellations.

Systemic Manifestations

Organ System	Characteristic Clinical Signs
Cutaneous And Mucosal	Pruritus, urticaria, facial swelling, erythema, profound lip and tongue swelling.
Respiratory	Upper airway edema causing stridor and hoarseness; lower airway narrowing causing bronchospasm, wheezing, and dyspnea.
Cardiovascular	Tachycardia, flushed warm extremities, bounding pulses, early flash capillary refill, wide pulse pressure, profound hypotension, syncope, shock.
Gastrointestinal	Nausea, vomiting, severe abdominal cramps.

Emergency Triage And Initial Assessment

Primary Triage Evaluation

• Mandates immediate rapid triage.
• Utilize Pediatric Assessment Triangle evaluating appearance, work of breathing, and circulation to skin.
• Initiate systematic rapid evaluation of Airway, Breathing, Circulation, and Disability.

Immediate Resuscitative Interventions

• Place child immediately in Trendelenburg position.
• Ensure supine posture with elevated legs.
• Maximize venous return to heart combatting recognized hypotension or airway threats.
• Perform mandatory bedside serum glucose testing.
• Rule out hypoglycemia in any altered mental status presentation.

Acute Emergency Management

First-Line Pharmacotherapy

Epinephrine Administration

• Constitutes absolute first-line treatment choice for anaphylactic shock.
• Mandates immediate administration upon clinical recognition.
• Acts on alpha-adrenergic receptors reversing peripheral vasodilation.
• Increases systemic vascular resistance and blood pressure.
• Acts on beta-adrenergic receptors inducing bronchodilation.
• Suppresses further mast cell mediator release directly.

Epinephrine Dosing Guidelines

• Utilize 1:1,000 concentration equivalent to 1 mg/mL solution.
• Administer standard pediatric dose of 0.01 mg/kg.
• Utilize strictly intramuscular route.
• Restrict maximum single dose to 0.5 mg for older children or adolescents.
• Repeat dose 2-3 times every 5-15 minutes.
• Indicate repetition for lack of rapid clinical improvement or symptom recurrence.

Airway And Respiratory Support

Oxygenation And Ventilation

• Administer immediate 100% supplemental oxygen.
• Utilize non-rebreather face mask aggressively treating hypoxemia.
• Anticipate emergency advanced airway management requirements.
• Prepare early for endotracheal intubation.
• Intubation indicated for severe upper airway obstruction secondary to progressive epiglottic or laryngeal edema.
• Recognize impending respiratory failure progresses rapidly to complete obstruction.

Bronchodilator Therapy

• Administer nebulized beta-agonists.
• Utilize salbutamol alongside intramuscular epinephrine.
• Indicated specifically for prominent bronchospasm and wheezing.

Hemodynamic Resuscitation

Vascular Access And Fluid Expansion

• Establish prompt intravenous or intraosseous access.
• Target restoration of intravascular volume lost to massive vasodilation and capillary leak.
• Administer isotonic crystalloids including Normal Saline or Ringer’s Lactate.
• Deliver rapid intravenous boluses of 20 mL/kg.
• Repeat fluid boluses for persistent hypotension or poor perfusion signs.
• Perform continuous reassessment identifying potential fluid overload signs.

Adjunctive Pharmacotherapy

Second-Line Medications

• Consider adjunctive therapies strictly second-line.
• Never delay intramuscular epinephrine administration for adjunctive treatments.

Medication Class	Drug And Dosage	Clinical Indication
Antihistamines	Chlorpheniramine or diphenhydramine administered intravenously or orally.	Relieves cutaneous symptoms including severe pruritus and urticaria.
Corticosteroids	Hydrocortisone 10 mg/kg intravenously; maximum 100 mg per dose.	Considered for severe symptoms or known asthmatics exhibiting significant persistent bronchospasm after other symptom resolution.

Management Of Refractory Anaphylactic Shock

Advanced Pharmacological Interventions

Continuous Epinephrine Infusion

• Suspect refractory anaphylaxis if shock persists despite multiple intramuscular epinephrine doses and adequate volume expansion.
• Initiate continuous intravenous epinephrine infusion.
• Commence continuous infusion at 0.1 micrograms/kg/min.
• Titrate upwards to maximum 1 microgram/kg/min.
• Guide titration via continuous hemodynamic monitoring and clinical response.

Environmental Control And Disposition

Source Eradication

• Ensure complete removal of inciting agent if still present.
• Remove retained insect stingers immediately.
• Discontinue offending intravenous medications or blood products instantaneously.

Ongoing Monitoring And Care

• Mandate admission to Pediatric Intensive Care Unit.
• Ensure continuous cardiovascular monitoring.
• Perform serial assessment of tissue perfusion parameters.
• Maintain prolonged continuous airway observation.