All EMS presentations
RespiratoryClinical presentation

Stridor / upper-airway obstruction

A streamlined, differential-led presentation for rapid clinical review.

Clinical snapshot

Twenty-second review

  • Stridor reflects turbulent airflow through a narrowed upper airway from infection, edema, foreign body, trauma, tumour, or functional obstruction.
  • Stridor at rest, drooling, voice change, severe retractions, exhaustion, cyanosis, or decreasing LOC indicates critical airway risk.
  • Keep vocal-cord dysfunction in the differential; overlapping or concurrent illness remains possible.
  • For stridor / upper-airway obstruction, trends and combinations of findings are more informative than one isolated vital sign.
Differentials

Compare the clinical patterns

The repeated material is grouped inside each possibility. Open only the condition you need.

Serious4 conditions
AnaphylaxisTime-sensitive high-risk possibility

HPI

Clarify sudden or gradual onset; voice change, drooling or dysphagia; allergen or foreign-body exposure.

Signs & symptoms

Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.

Focused exam

Observe position, speech, accessory-muscle use, pattern, depth, and chest symmetry; Auscultate all lung fields and reassess after movement or treatment.

Brief pathophysiology

Anaphylaxis may cause stridor / upper-airway obstruction through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Anaphylaxis may involve airway, breathing, or circulation alone or in combination. Do not wait for hypotension, hypoxemia, or skin findings before recognizing a severe reaction.

Blood pressure (mmHg)

May fall

Vasodilation and capillary leak can cause rapid hypotension.

Heart rate (bpm)

Often rises

Tachycardia may accompany shock, distress, or epinephrine treatment.

Respiratory rate (breaths/min)

Often rises

Tachypnea may reflect bronchospasm, airway edema, or shock.

Oxygen saturation (SpO₂)

May fall

Desaturation suggests significant respiratory involvement but may be late.

Front-load in the triage report

  • Anaphylaxis: Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.
  • Sudden or gradual onset?
  • Voice change, drooling or dysphagia?
Foreign bodyTime-sensitive high-risk possibility

HPI

Clarify voice change, drooling or dysphagia; allergen or foreign-body exposure; air movement and work of breathing.

Signs & symptoms

Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.

Focused exam

Auscultate all lung fields and reassess after movement or treatment; Keep the patient calm; assess voice, drooling, swelling, exposure, neck trauma, air entry, and ability to handle secretions without provoking obstruction.

Brief pathophysiology

Foreign body may cause stridor / upper-airway obstruction through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Airway sounds, voice, work of breathing, and trajectory are more important than a single normal SpO₂. Deteriorating effort or rate may indicate fatigue, not improvement.

Respiratory rate (breaths/min)

Usually rises first

Tachypnea and increased effort commonly precede late respiratory failure.

Oxygen saturation (SpO₂)

May fall late

Oxygen saturation can remain normal until obstruction becomes severe.

Heart rate (bpm)

Often rises

Tachycardia may reflect hypoxia, distress, or compensatory response.

Blood pressure (mmHg)

Usually preserved

Hypotension suggests advanced hypoxia, anaphylaxis, or another shock state.

Front-load in the triage report

  • Foreign body: Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.
  • Voice change, drooling or dysphagia?
  • Allergen or foreign-body exposure?
EpiglotticTime-sensitive high-risk possibility

HPI

Clarify allergen or foreign-body exposure; air movement and work of breathing; swelling or hives.

Signs & symptoms

Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.

Focused exam

Auscultate all lung fields and reassess after movement or treatment; Keep the patient calm; assess voice, drooling, swelling, exposure, neck trauma, air entry, and ability to handle secretions without provoking obstruction.

Brief pathophysiology

Epiglottic may cause stridor / upper-airway obstruction through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Airway sounds, voice, work of breathing, and trajectory are more important than a single normal SpO₂. Deteriorating effort or rate may indicate fatigue, not improvement.

Respiratory rate (breaths/min)

Usually rises first

Tachypnea and increased effort commonly precede late respiratory failure.

Oxygen saturation (SpO₂)

May fall late

Oxygen saturation can remain normal until obstruction becomes severe.

Heart rate (bpm)

Often rises

Tachycardia may reflect hypoxia, distress, or compensatory response.

Blood pressure (mmHg)

Usually preserved

Hypotension suggests advanced hypoxia, anaphylaxis, or another shock state.

Front-load in the triage report

  • Epiglottic: Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.
  • Allergen or foreign-body exposure?
  • Air movement and work of breathing?
Deep-neck infectionTime-sensitive high-risk possibility

HPI

Clarify air movement and work of breathing; swelling or hives; treatment and response.

Signs & symptoms

Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.

Focused exam

Auscultate all lung fields and reassess after movement or treatment; Keep the patient calm; assess voice, drooling, swelling, exposure, neck trauma, air entry, and ability to handle secretions without provoking obstruction.

Brief pathophysiology

Deep-neck infection may cause stridor / upper-airway obstruction through a time-sensitive process capable of rapid physiological deterioration.

Vital-sign pattern

What the trend may show

Possible pattern

Airway sounds, voice, work of breathing, and trajectory are more important than a single normal SpO₂. Deteriorating effort or rate may indicate fatigue, not improvement.

Respiratory rate (breaths/min)

Usually rises first

Tachypnea and increased effort commonly precede late respiratory failure.

Oxygen saturation (SpO₂)

May fall late

Oxygen saturation can remain normal until obstruction becomes severe.

Heart rate (bpm)

Often rises

Tachycardia may reflect hypoxia, distress, or compensatory response.

Blood pressure (mmHg)

Usually preserved

Hypotension suggests advanced hypoxia, anaphylaxis, or another shock state.

Front-load in the triage report

  • Deep-neck infection: Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.
  • Air movement and work of breathing?
  • Swelling or hives?
Common2 conditions
CroupCommon presentation pattern

HPI

Clarify sudden or gradual onset; voice change, drooling or dysphagia; allergen or foreign-body exposure.

Signs & symptoms

Barking cough, fever, and age may support the pattern.

Focused exam

Observe position, speech, accessory-muscle use, pattern, depth, and chest symmetry; Auscultate all lung fields and reassess after movement or treatment.

Brief pathophysiology

Croup may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Airway sounds, voice, work of breathing, and trajectory are more important than a single normal SpO₂. Deteriorating effort or rate may indicate fatigue, not improvement.

Respiratory rate (breaths/min)

Usually rises first

Tachypnea and increased effort commonly precede late respiratory failure.

Oxygen saturation (SpO₂)

May fall late

Oxygen saturation can remain normal until obstruction becomes severe.

Heart rate (bpm)

Often rises

Tachycardia may reflect hypoxia, distress, or compensatory response.

Blood pressure (mmHg)

Usually preserved

Hypotension suggests advanced hypoxia, anaphylaxis, or another shock state.

Front-load in the triage report

  • Barking cough, fever, and age may support the pattern.
  • Sudden or gradual onset?
  • Voice change, drooling or dysphagia?
Inflammatory swellingCommon presentation pattern

HPI

Clarify voice change, drooling or dysphagia; allergen or foreign-body exposure; air movement and work of breathing.

Signs & symptoms

Barking cough, fever, and age may support the pattern.

Focused exam

Auscultate all lung fields and reassess after movement or treatment; Keep the patient calm; assess voice, drooling, swelling, exposure, neck trauma, air entry, and ability to handle secretions without provoking obstruction.

Brief pathophysiology

Inflammatory swelling may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.

Vital-sign pattern

What the trend may show

Possible pattern

Airway sounds, voice, work of breathing, and trajectory are more important than a single normal SpO₂. Deteriorating effort or rate may indicate fatigue, not improvement.

Respiratory rate (breaths/min)

Usually rises first

Tachypnea and increased effort commonly precede late respiratory failure.

Oxygen saturation (SpO₂)

May fall late

Oxygen saturation can remain normal until obstruction becomes severe.

Heart rate (bpm)

Often rises

Tachycardia may reflect hypoxia, distress, or compensatory response.

Blood pressure (mmHg)

Usually preserved

Hypotension suggests advanced hypoxia, anaphylaxis, or another shock state.

Front-load in the triage report

  • Barking cough, fever, and age may support the pattern.
  • Voice change, drooling or dysphagia?
  • Allergen or foreign-body exposure?
Mimics1 condition
Vocal-cord dysfunctionImportant alternative presentation

HPI

Clarify sudden or gradual onset; voice change, drooling or dysphagia; allergen or foreign-body exposure.

Signs & symptoms

May mimic obstruction but is a diagnosis of exclusion in the acute setting.

Focused exam

Observe position, speech, accessory-muscle use, pattern, depth, and chest symmetry; Auscultate all lung fields and reassess after movement or treatment.

Brief pathophysiology

Vocal-cord dysfunction can resemble stridor / upper-airway obstruction through overlapping symptoms or referred physiology despite a different primary mechanism.

Vital-sign pattern

What the trend may show

Possible pattern

Airway sounds, voice, work of breathing, and trajectory are more important than a single normal SpO₂. Deteriorating effort or rate may indicate fatigue, not improvement.

Respiratory rate (breaths/min)

Usually rises first

Tachypnea and increased effort commonly precede late respiratory failure.

Oxygen saturation (SpO₂)

May fall late

Oxygen saturation can remain normal until obstruction becomes severe.

Heart rate (bpm)

Often rises

Tachycardia may reflect hypoxia, distress, or compensatory response.

Blood pressure (mmHg)

Usually preserved

Hypotension suggests advanced hypoxia, anaphylaxis, or another shock state.

Front-load in the triage report

  • May mimic obstruction but is a diagnosis of exclusion in the acute setting.
  • Sudden or gradual onset?
  • Voice change, drooling or dysphagia?
Red flags

Findings that should escalate concern

  • Silent or worsening airway
  • Cyanosis
  • Exhaustion
  • Altered LOC
  • Stridor at rest, drooling, voice change, severe retractions, exhaustion, cyanosis, or decreasing LOC indicates critical airway risk.
  • Anaphylaxis, foreign body, epiglottic or deep-neck infection: Rapid swelling, sudden onset, drooling, toxic appearance, or exposure.
Related medications

Medication recognition

AmoxicillinCephalexinDoxycycline
Related EMS presentations

Continue the clinical pathway

Allergic/ImmunologicAllergic reaction / anaphylaxisRespiratoryChoking / airway foreign bodyPediatricPediatric respiratory distressGIDysphagia / swallowing difficultyAllergic/ImmunologicAngioedema
References

Clinical and academic sources

Curated clinical guidance and peer-reviewed evidence supporting this presentation. Current BCEHS guidance, medical direction, and local policy remain authoritative for practice.

BCEHS Handbook — specific CPGs

  1. B01: Airway ManagementBC Emergency Health Services Handbook

    Official BCEHS clinical practice guidance for airway management.

  2. B04: Croup and EpiglottitisBC Emergency Health Services Handbook

    Official BCEHS clinical practice guidance for croup and epiglottitis.

Supporting clinical and academic evidence

  1. CEDIS Presenting Complaint List updateCanadian Association of Emergency Physicians

    Presenting-complaint terminology and categorization context. It does not establish a prehospital “top 100” ranking.

  2. Guideline for oxygen use in adults in healthcare and emergency settingsBritish Thoracic Society

    Peer-reviewed guidance for oxygen assessment, targets, delivery, and monitoring in acute illness.

  3. Evaluation and Management of Airway Foreign Bodies in the Emergency Department SettingJournal of Emergency Medicine · 2023

    Upper-airway obstruction assessment, foreign-body clues, airway planning, and deterioration risk.