# A nurse is caring for a client who is experiencing anaphylaxis after receiving a penicillin injection. Which nursing action should be the priority?

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> subject: Adult Health

## 문제

A nurse is caring for a client who is experiencing anaphylaxis after receiving a penicillin injection. Which nursing action should be the priority?

## 보기

1. Administer diphenhydramine 50 mg IV push
2. Start an IV line with normal saline
3. Place the client in Trendelenburg position
4. Administer epinephrine 0.3-0.5 mg intramuscularly **✔ 정답**

**정답: 4**

## 해설

Epinephrine is the priority in anaphylaxis as it directly counteracts life-threatening cardiovascular and respiratory effects. Other interventions like antihistamines, IV fluids, and positioning are supportive but secondary.

## 심화 해설

Priority Action in Anaphylaxis

The correct answer is administer epinephrine 0.3-0.5 mg intramuscularly. In the setting of anaphylaxis, a severe and rapidly progressing hypersensitivity reaction, the physiological priority is to reverse the life-threatening effects of massive vasodilation, increased vascular permeability, and bronchoconstriction. Epinephrine is the first-line pharmacological intervention because it directly counteracts these mechanisms through its alpha- and beta-adrenergic agonist properties. Alpha-1 agonism causes vasoconstriction, which elevates blood pressure, reduces laryngeal and airway edema, and decreases urticaria. Beta-1 agonism increases cardiac contractility and heart rate, supporting cardiac output, while beta-2 agonism induces bronchodilation, relieving respiratory distress and wheezing. The intramuscular route into the anterolateral thigh is preferred for its rapid and predictable absorption in a hemodynamically unstable patient, where establishing intravenous access can be difficult and time-consuming [2]. Delaying epinephrine administration to first start an IV line, administer a second-line agent like an antihistamine, or reposition the client can allow the anaphylactic cascade to progress to airway obstruction and cardiovascular collapse. The clinical urgency of anaphylaxis mirrors the time-sensitive nature of other critical events, such as cardiac arrest, where epinephrine is also a key first-line medication to support perfusion and the return of spontaneous circulation [2]. While the provided evidence focuses on penicillin allergy management and the critical role of epinephrine in resuscitation, the foundational principle remains that in anaphylaxis, immediate epinephrine administration is the single most critical action to prevent mortality.References (research sources)

- [2]Evaluating intramuscular epinephrine in pediatric out-of-hospital cardiac arrest (the PRIME trial): study protocol for a multi-centre, stepped-wedge cluster quasi-randomized controlled trial.RCT/clinical trialIdrees S, Assaf M, Davis M, Garcia-Bournissen F, Loosley J, Miller MR, Tijssen JA. (2026) · DOI: 10.1186/s13063-026-09776-3

## 임상 시나리오

Anaphylaxis: First-Line ManagementEpinephrine is the priority intervention to prevent airway and circulatory collapse.
Administer epinephrine 0.3–0.5 mg intramuscularly into the anterolateral thigh immediately upon recognizing anaphylaxis. This is the only first-line agent that reverses vasodilation and bronchoconstriction.

Second-line interventions such as diphenhydramine, corticosteroids, or inhaled beta-agonists are adjuncts and should never delay epinephrine administration. Establish IV access and give supplemental oxygen after the initial epinephrine dose.

CautionDo not delay epinephrine to start an IV line or give antihistamines. In hemodynamically unstable patients, IM absorption is more reliable than subcutaneous injection.

## 핵심 개념

- **Anaphylaxis** — A severe, life-threatening systemic hypersensitivity reaction characterized by rapid onset of airway, breathing, and circulatory problems.
- **Epinephrine** — First-line vasopressor for anaphylaxis with alpha-1 (vasoconstriction) and beta-2 (bronchodilation) agonist effects.
- **Intramuscular (IM) Route** — Preferred initial route for epinephrine in anaphylaxis, given into the anterolateral thigh for rapid absorption.
- **Diphenhydramine** — An H1-receptor antagonist (antihistamine) used as a second-line adjunct to relieve urticaria and itching, not for reversing shock.
- **Priority Setting** — In anaphylaxis, airway and circulation management with epinephrine takes precedence over IV access, positioning, or antihistamines.

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