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Difficulty: MediumPhysiological Adaptation

A nurse is monitoring a client who is receiving an intravenous infusion of a prescribed antibiotic. Fifteen minutes after the infusion starts, the client becomes restless and reports a feeling of impending doom. Which assessment finding should the nurse identify as the most definitive indicator that the client is developing anaphylactic shock?

  1. A
    A blood pressure shift from 124/76 mm Hg to 118/88 mm Hg
  2. B
    Arterial blood gas values showing a pH of 7.48 and a PaCO2\text{PaCO}_2 of 28 mm Hg
  3. Diffuse expiratory wheezing and a heart rate of 122/minAnswer
  4. D
    Erythema and induration strictly localized to the intravenous insertion site

Answer

The most definitive indicator of anaphylactic shock is diffuse expiratory wheezing combined with significant tachycardia.
Anaphylactic shock is a distributive shock characterized by sudden mast cell degranulation, leading to systemic vasodilation and profound bronchoconstriction. Diffuse expiratory wheezing directly indicates life-threatening airway compromise, while tachycardia is the rapid compensatory response to the massive drop in systemic vascular resistance. Together, these form the classic clinical presentation requiring immediate epinephrine administration.

Step-by-Step Solution

1
Analyze the client's initial symptoms (restlessness, impending doom) within the context of receiving an intravenous antibiotic.
Identify that the client is at high risk for a systemic hypersensitivity reaction.
Restlessness and a feeling of impending doom are classic early, subjective signs of anaphylaxis before overt hemodynamic collapse.
2
Recall the underlying pathophysiology of anaphylactic shock.
Determine that anaphylaxis involves massive systemic vasodilation and severe bronchoconstriction.
Mast cell degranulation releases histamine, which relaxes vascular smooth muscle (distributive shock) and constricts bronchial smooth muscle.
3
Evaluate the clinical findings in each option against the expected pathophysiology of anaphylaxis.
Identify wheezing and tachycardia as the signs that directly match bronchospasm and the compensatory cardiac response to vasodilation.
Narrowing pulse pressure indicates hypovolemic or compensatory shock, while respiratory alkalosis is a non-specific anxiety or early hypoxic response.

Key Concept

Early recognition of systemic anaphylaxis requires identifying signs of distributive shock (vasodilation causing tachycardia and eventual hypotension) combined with airway compromise (bronchospasm causing wheezing).
Estimated Time:1m 0s
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Physiological Adaptation

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