Algorithm

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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

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.

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.