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History
HPI overview
Angioedema episode characterization
Location
Number of sites
Lip
Tongue
Floor of mouth
Uvula
Larynx voice change
Face
Periorbital
Hands
Feet
Genital
Abdominal
Time course
Rapid progression minutes to hours
Gradual progression hours to days
Duration
Prior episodes
Similar pattern
First episode
Onset
Onset details
Time of first symptom
Time of peak swelling
Wake from sleep onset
Post procedure onset
Provocation/Palliation
Triggers and modifiers
New medication within weeks to months
Recent dose change
Recent infection
Food exposure
Insect sting
Latex exposure
Exercise associated
Heat exposure
Cold exposure
Pressure trigger
Dental work
Minor trauma
Stress
Alcohol exposure
Quality
Symptom quality
Swelling non pitting
Burning
Painful swelling
Itchy swelling
Tightness
Region/Radiation
Anatomic spread pattern
Unilateral
Bilateral
Migratory swelling
Progressive cephalad spread
Severity
Severity markers
Speech change
Dysphagia
Drooling
Dyspnea
Stridor
Inability to handle secretions
Timing
Timing pattern
Single episode
Recurrent episodes
Nocturnal recurrence
Relation to medication ingestion time
Associated symptoms
Associated features
Urticaria
Pruritus
Flushing
Wheeze
Chest tightness
Hypotension symptoms
Syncope
Nausea
Vomiting
Diarrhea
Abdominal pain
Fever
Sore throat
Odynophagia
Recent trauma
Phenotype clues
Mechanism clues
Histamine mediated clues
Urticaria present
Pruritus present
Rapid response to antihistamine
Clear allergic trigger
Bradykinin mediated clues
No urticaria
Poor response to antihistamine
Recurrent abdominal pain episodes
ACE inhibitor exposure
Special populations history
Context modifiers
Pregnancy and postpartum status
Pediatric age group
Immunocompromised status
Anticoagulant use history
Alarm Features
Airway red flags
Impending airway compromise
Stridor
Muffled voice
Hoarseness
Drooling
Dysphagia
Inability to handle secretions
Tongue enlargement
Floor of mouth swelling
Rapid progression
Prior intubation for angioedema
Anaphylaxis red flags
Systemic allergic reaction features
Hypotension
Bronchospasm
Hypoxia
Syncope
Widespread urticaria
Repetitive vomiting
Vital sign danger thresholds
High risk physiology
SpO2 less than 92 percent on room air
Systolic blood pressure less than 90 mmHg
Respiratory rate greater than 30 per minute
Marked tachycardia with poor perfusion
High risk etiologies
High risk contexts
ACE inhibitor associated tongue swelling
Hereditary angioedema with laryngeal symptoms
Recent head and neck procedure
Deep neck infection concern
Escalation triggers
Immediate escalation
Any airway symptom progression during observation
Need for repeated epinephrine dosing
Worsening hypoxia
Hemodynamic instability
Medications
Culprit medication screen
Medication triggers
ACE inhibitors
Angiotensin receptor blockers
Sacubitril valsartan
DPP 4 inhibitors
Estrogen containing therapies
NSAIDs
Antibiotics
Opioids
Radiocontrast exposure
Current therapies and interactions
Relevant current medications
Beta blocker use
ACE inhibitor continuation after prior event
Antihistamine use prior to arrival
Corticosteroid use prior to arrival
Epinephrine auto injector availability
Hereditary angioedema therapies
HAE specific medications
On demand C1 inhibitor concentrate
Icatibant
Ecallantide
Prophylaxis lanadelumab
Prophylaxis berotralstat
Anticoagulants and airway procedure risk
Bleeding risk modifiers
DOAC use
Warfarin use
Antiplatelet therapy
Diet
Exposure review
Possible dietary triggers
New food exposure
Known food allergy exposure
Shellfish exposure
Peanut and tree nut exposure
Food additives exposure
Alcohol and histamine related exposures
Intake modifiers
Alcohol intake within 24 hours
Fermented foods exposure
Aged cheeses exposure
Hydration and intake
Intake context
Reduced oral intake
Vomiting or diarrhea related dehydration
Review of Systems
Skin and allergy
Skin and allergy symptoms
Urticaria
Pruritus
Flushing
Eczema flare
Respiratory
Respiratory symptoms
Dyspnea
Wheeze
Cough
Chest tightness
Stridor
ENT and oral
Upper airway symptoms
Throat tightness
Voice change
Dysphagia
Drooling
Odynophagia
Gastrointestinal
Gastrointestinal symptoms
Abdominal pain
Nausea
Vomiting
Diarrhea
Cardiovascular and neurologic
Systemic symptoms
Lightheadedness
Syncope
Palpitations
Confusion
Collateral History and Family History
Collateral source
Collateral context
Source
Reliability
Witnessed progression timing
Family history
Family history patterns
Recurrent swelling without hives
Family history of hereditary angioedema
Family history of sudden airway events
Family history of autoimmune disease
Household and exposure context
Exposure history
Sick contacts
New pets
Recent travel
New household products
Risk Factors
Medication and disease risks
Predisposing risks
ACE inhibitor use duration and dose
Prior angioedema episodes
History of atopy
Asthma diagnosis (J45.909)
Acquired C1 inhibitor deficiency risks
Acquired bradykinin angioedema risks
Lymphoproliferative disorder history
Monoclonal gammopathy history
Autoimmune disease history
Procedure and trauma risks
Mechanical triggers
Recent dental work
Recent intubation
Oropharyngeal trauma
Special population risks
Higher consequence contexts
Pregnancy
Pediatric airway size
Limited access to emergency care
Differential Diagnosis
Life threatening
Life threatening causes
Anaphylaxis (T78.2)
Multi system involvement
Hypotension
Bronchospasm
Laryngeal angioedema
Stridor
Voice change
Deep neck space infection
Fever
Trismus
Toxic appearance
Ludwig angina
Floor of mouth swelling
Dental infection source
Epiglottitis
Severe sore throat
Drooling
Common
Common causes
Histamine mediated angioedema (T78.3)
Urticaria present
Pruritus present
Idiopathic angioedema (T78.3)
No trigger found
Recurrent episodes
ACE inhibitor induced angioedema (T46.4X5A)
No urticaria
Tongue and facial predominance
NSAID associated angioedema (T39.395A)
Temporal relation to NSAID
Coexisting urticaria possible
Less common
Less common causes
Hereditary angioedema (D84.1)
Recurrent swelling
Abdominal pain episodes
Family history
Acquired C1 inhibitor deficiency angioedema
Later onset
Autoimmune or malignancy association
Physical urticaria with angioedema (L50.8)
Pressure induced
Cold induced
Contact reaction
Localized exposure pattern
Burning and pruritus
Mimics and distinguishing clues
Mimics
Cellulitis
Erythema warmth tenderness
Fever
Facial trauma hematoma
Ecchymosis
Clear trauma history
Dental abscess
Tooth pain
Local fluctuance
Past Medical History
Prior episodes and baseline
Prior angioedema history
Number of prior episodes
Prior airway involvement
Prior intubation
Prior ICU admission
Allergy and atopy history
Atopic conditions
Food allergy history
Medication allergy history
Allergic rhinitis (J30.9)
Asthma (J45.909)
Comorbid disease relevant to acquired forms
Associated conditions
Autoimmune disease
Lymphoproliferative disease
Thyroid disease
Surgical and procedure history
Airway relevant history
Head and neck surgery
Tonsillectomy
Difficult airway history
Physical Exam
General and vitals
Global severity
Toxic appearance
Work of breathing
Voice quality
Vital sign interpretation pattern
Airway and ENT
Upper airway exam
Lip swelling
Tongue size
Floor of mouth elevation
Uvular edema
Trismus
Drooling
Stridor
Ability to speak full sentences
Skin
Skin findings
Urticaria
Flushing
Angioedema without erythema
Rash morphology suggesting alternative diagnosis
Respiratory and cardiovascular
Cardiopulmonary findings
Wheeze
Air entry
Accessory muscle use
Perfusion
Capillary refill
Abdominal and neurologic
Associated system findings
Abdominal tenderness
Guarding
Altered mental status
Syncope aftermath
Lab Studies
Core labs when systemic illness or alternative diagnosis concern
Baseline evaluation
CBC
CMP
Venous blood gas if respiratory compromise
Anaphylaxis and mast cell evaluation
Allergic mechanism evaluation
Serum tryptase timing
Peak sample within 1 to 3 hours from symptom onset
Baseline sample at least 24 hours after resolution
Bradykinin mediated evaluation
Complement pathway evaluation
C4 level
C1 inhibitor level
C1 inhibitor function
C1q level for acquired forms
Infection and inflammation evaluation when indicated
Infection workup
CRP
Blood cultures with sepsis physiology
Lactate with shock physiology
Pitfalls and limitations
Interpretation caveats
Normal C4 possible between attacks in some HAE variants
Complement tests do not guide acute ED airway decisions
Imaging
Scoring Systems
Risk stratification frameworks
Airway risk based on anatomic site
Tongue and larynx highest risk
Isolated lip lower risk
MRI
MRI considerations
Rare in acute angioedema workup
Alternative diagnosis evaluation for deep neck pathology when CT contraindicated
CT
CT considerations
CT neck with contrast for deep neck infection concern
Radiation caution in pregnancy
Contrast allergy history relevance
Ultrasound
Ultrasound considerations
POCUS soft tissue for abscess versus cellulitis mimics
Airway ultrasound adjunct for anatomy in anticipated difficult airway
Special Tests
Bedside airway evaluation
Airway assessment tools
Nasopharyngolaryngoscopy
Indicated with voice change stridor drooling or tongue progression
Limited value if unavailable or patient unstable
Allergy directed testing planning
Outpatient and follow up testing
Allergy referral for trigger identification
Medication challenge planning not in ED setting
Hereditary angioedema focused testing
HAE evaluation pathway
Repeat complement testing after resolution if initial borderline
Genetic testing referral when indicated by specialist
ECG
Indications
ECG triggers
Chest pain
Palpitations
Syncope
Epinephrine administration in older patients or cardiac history
High risk patterns
ECG findings of concern
Ischemic changes
Significant tachyarrhythmia
Prolonged QT with antihistamine exposure risk context
Assessment
Working diagnosis and mechanism
Angioedema classification
Histamine mediated angioedema (T78.3)
Bradykinin mediated angioedema
ACE inhibitor induced angioedema (T46.4X5A)
Hereditary angioedema (D84.1)
Severity stratification
Severity level
Low risk site limited
Lip or periorbital only
Moderate risk
Tongue involvement without symptoms
High risk
Voice change stridor drooling hypoxia
Complications to rule out
Cannot miss complications
Anaphylaxis (T78.2)
Deep neck infection
Airway compromise progression during observation
Evidence synthesis
Key supporting features
Urticaria presence versus absence
Medication exposure pattern
Response to initial therapy
Airway symptoms trajectory
Plan
First 5 minutes
Immediate stabilization workflow
Airway positioning and suction readiness
Continuous pulse oximetry
Cardiac monitor
Two IV lines if airway risk or anaphylaxis concern
Oxygen if SpO2 less than 94 percent
Early airway team activation triggers
Voice change
Stridor
Drooling
Rapid tongue progression
Airway strategy
Airway management principles
Early decision making before progression
Awake fiberoptic intubation consideration with anticipated difficult airway
Surgical airway equipment readiness
Avoid repeated traumatic attempts
Histamine mediated treatment
Allergic pathway treatment
Epinephrine IM 0.3 mg of 1 mg per mL for anaphylaxis concern
Repeat IM every 5 to 15 minutes if ongoing anaphylaxis physiology
Cetirizine PO 10 mg if able to swallow and non severe
Diphenhydramine IV 25 mg to 50 mg as adjunct if severe symptoms
Famotidine IV 20 mg as adjunct
Dexamethasone IV 10 mg or methylprednisolone IV 125 mg adjunct
Nebulized epinephrine as bridge for upper airway symptoms local protocol dependent
Bradykinin mediated treatment
Bradykinin pathway treatment
Immediate discontinuation of ACE inhibitor
C1 inhibitor concentrate dosing per product and protocol
Icatibant dosing per product and protocol
Fresh frozen plasma 2 units if specific agents unavailable local protocol dependent
Tranexamic acid dosing local protocol dependent
Consultation plan
Team involvement
Anesthesia for anticipated difficult airway
ENT for laryngoscopy and airway planning
ICU for high risk airway or hemodynamic instability
Allergy immunology follow up for recurrent or unclear mechanism
Monitoring and reassessment loop
Reassessment cadence
Airway symptom check every 15 to 30 minutes early course
Repeat focused oral exam for tongue and floor of mouth progression
Repeat vitals after epinephrine administration
Escalate level of care if any progression
Disposition
ICU criteria
ICU level care triggers
Any laryngeal involvement
Stridor or voice change
Need for intubation
Ongoing anaphylaxis physiology
Inpatient or observation criteria
Admission or extended observation
Tongue involvement even without symptoms
Progression during ED stay
Bradykinin mediated suspected with uncertain trajectory
Limited follow up reliability
Discharge criteria
Safe discharge features
Symptoms improving and stable for observation period
No airway symptoms
No progression on serial exams
Trigger removed when applicable
Epinephrine auto injector provided when anaphylaxis risk
Follow up timing
Follow up plan
Primary care within 2 to 7 days
Allergy immunology referral for recurrent episodes
HAE specialist referral when complement abnormalities or strong suspicion
Discharge Instructions
Copy discharge instructions
Patient facing summary
You were seen for swelling called angioedema
This can be allergic or medication related and can sometimes affect breathing
Your symptoms today were stable and improved with treatment
Avoid the suspected trigger
Do not restart the suspected medication if told it may be the cause
If you were on an ACE inhibitor your prescriber should switch you to a different medication
Take the prescribed antihistamine as directed
If you were prescribed an epinephrine auto injector carry it at all times
Return to the emergency department immediately for any trouble breathing
Return immediately for voice change
Return immediately for throat tightness
Return immediately for tongue swelling
Return immediately for drooling or trouble swallowing
Return immediately for dizziness or fainting
Follow up with your clinician within the recommended time frame
References
Guidelines and key sources
Evidence based references
World Allergy Organization anaphylaxis guidance 2020
AAAAI ACAAI Joint Task Force anaphylaxis practice parameter update 2023
AAEM clinical practice guideline acute urticaria and angioedema emergency department
International WAO EAACI guideline hereditary angioedema 2021 revision and update published 2022
CMAJ review ACE inhibitor induced angioedema 2021
Project instructions source
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.