Guide — Emergency Respiratory Care
Anaphylaxis & Acute Airway Emergencies
When the airway is closing — how to recognize anaphylaxis fast, why intramuscular epinephrine is the immediate first-line drug, the adjuncts (oxygen, nebulized epinephrine, bronchodilators, antihistamines, steroids), and the airway plan when angioedema threatens to obstruct.
9 min read · Emergency Respiratory Care
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
Anaphylaxis is a rapid, life-threatening systemic allergic reaction. The respiratory threats are upper-airway angioedema (obstruction) and lower-airway bronchospasm. Recognizing it and giving immediate intramuscular epinephrine saves lives; the RT supports oxygenation and ventilation and prepares for a difficult airway. Real emergencies always follow current ACLS and local protocols under physician orders — this guide is a study framework, not a substitute for them.
Key Concepts
- Recognition (any one pattern). Acute onset with skin or mucosal involvement (hives, lip or tongue swelling) PLUS respiratory compromise or hypotension; OR two or more organ systems involved after a likely allergen; OR hypotension after a known allergen. Do not wait for hives — they can be absent.
- The respiratory danger. Laryngeal, tongue, or pharyngeal angioedema (stridor, voice change, a “lump in the throat”) causing upper-airway obstruction, plus bronchospasm and wheeze in the lower airway.
- Epinephrine is first-line and immediate. Intramuscular into the anterolateral thigh (adult 0.3–0.5 mg of the 1 mg/mL concentration), repeated every 5–15 minutes as needed. It reverses airway edema and bronchospasm and supports blood pressure, and there is no absolute contraindication in true anaphylaxis.
- Antihistamines and corticosteroids are adjuncts. They do not replace epinephrine and act too slowly to treat the acute airway.
Assessment & Findings
Diagnose clinically — meeting any one recognition pattern is enough to treat. Do not delay for a textbook presentation.
| Pattern | Criteria | Note |
|---|---|---|
| Skin/mucosal + system failure | Acute onset with hives or lip/tongue swelling PLUS respiratory compromise or hypotension | The classic presentation |
| Two or more systems | Two or more organ systems involved after a likely allergen | Skin, respiratory, GI, or cardiovascular |
| Hypotension alone | Hypotension after exposure to a known allergen | Skin findings may be absent |
| Finding | Points To |
|---|---|
| Stridor, hoarseness, tongue/lip swelling, trouble swallowing | Impending upper-airway obstruction (angioedema) |
| Wheeze, dyspnea, falling SpO₂ | Lower-airway bronchospasm |
| Hypotension and tachycardia | Distributive shock |
RT Priorities & Interventions
- Epinephrine first, without delay. Ensure intramuscular epinephrine is given — the single most important intervention.
- Oxygenate and support ventilation. Provide high-flow or 100% oxygen and support ventilation.
- Adjuncts. Nebulized epinephrine for laryngeal edema and stridor, nebulized albuterol for bronchospasm, IV fluids for hypotension, and H1/H2 antihistamines and corticosteroids as adjuncts.
- Prepare for a difficult airway early. Angioedema distorts the anatomy. Have the difficult-airway plan, smaller tubes, and a surgical-airway backup ready, and let the most experienced operator intubate.
- Position to the dominant problem. Upright if the airway predominates, or supine with legs raised if hypotensive.
Common Pitfalls
- Giving antihistamines or steroids first and delaying epinephrine — epinephrine is the immediate life-saving drug.
- Waiting for hives before treating — anaphylaxis can present without any skin findings.
- Underestimating how fast angioedema closes an airway — secure it early with the most experienced operator and backup plans.
Board Exam Pearls
- Intramuscular epinephrine (anterolateral thigh) is first-line and immediate; repeat as needed.
- Antihistamines and corticosteroids are adjuncts, not substitutes for epinephrine.
- Nebulized epinephrine helps laryngeal edema and stridor; albuterol helps bronchospasm.
- Anaphylaxis can occur without hives.
- Anticipate a difficult airway from angioedema — early, expert intubation with backup.
FAQ
What is the first drug in anaphylaxis?
Intramuscular epinephrine into the anterolateral thigh, given immediately - it reverses airway swelling and bronchospasm and supports blood pressure. Antihistamines and corticosteroids are adjuncts that act too slowly to treat the acute airway and never replace epinephrine.
Can anaphylaxis happen without a rash?
Yes. A substantial minority of cases have no skin findings. Rapid-onset respiratory compromise or hypotension after a likely allergen is enough to treat as anaphylaxis - do not wait for hives.
Why is the airway so dangerous in anaphylaxis?
Angioedema of the tongue, pharynx, and larynx can swell the upper airway shut within minutes, producing stridor and a voice change. Anticipate a difficult intubation, secure the airway early with the most experienced operator, and have smaller tubes and a surgical-airway backup ready.
What is the RT's role beyond epinephrine?
Deliver high-flow oxygen, support ventilation, give nebulized epinephrine for laryngeal edema and albuterol for bronchospasm, and prepare the difficult-airway equipment and plan while the team gives intramuscular epinephrine and IV fluids.
Put it to work
When the airway is closing, the gas tracks the oxygenation and ventilation. Practice reading it.
Open the ABG Interpreter →Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Emergency airway management and pharmacology chapters.
- Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123.