Typical finding in anaphylactic shock?

KPSC Staff Nurse - 2015

Medical & Surgical Nursing

Easy

Appeared in: KPSC Staff Nurse - 2015

Explanation

Wheezing is a hallmark respiratory sign of anaphylaxis, caused by bronchoconstriction and airway edema from the release of histamine and other inflammatory mediators.
This expiratory sound indicates a narrowing of the lower airways and is a critical diagnostic clue for anaphylaxis.
While other signs like tachycardia occur, wheezing is highly characteristic of the specific allergic inflammatory process affecting the respiratory system in anaphylaxis.

Option A: Anuria (absence of urine) is a sign of severe kidney hypoperfusion and acute kidney injury. This is a late and grave complication of prolonged shock, not an initial or typical finding.
Option B: While tachycardia is almost always present in anaphylactic shock as the body attempts to compensate for hypotension, it is a non-specific sign of all types of shock. Wheezing is more specific to the underlying pathology of anaphylaxis.
Option D: Anaphylaxis causes widespread vasodilation due to massive histamine release, leading to a rapid and severe drop in blood pressure (hypotension), which is the opposite of hypertension.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Clinical signs and symptoms of anaphylactic shock as background academic context rather than a clinical decision trigger.
Recognizing wheezing as a key sign of anaphylaxis is critical for nurses to trigger an immediate emergency response, including the administration of intramuscular epinephrine, which is life-saving.
Patient safety depends on rapidly differentiating anaphylaxis from other conditions. For example, while both can cause wheezing, an asthma attack is treated primarily with bronchodilators, whereas anaphylaxis requires epinephrine first.
What if? If the patient presented with stridor (a high-pitched sound on inhalation) instead of wheezing, it would indicate a more critical upper airway obstruction (laryngeal edema). This is an immediate life-threat requiring urgent airway management, possibly intubation, in addition to epinephrine.

How to Approach the Question

Analyze the question: it asks for a 'typical' finding in anaphylactic shock. This requires identifying the most characteristic sign that defines the condition.
Recall the core pathophysiology of anaphylaxis: it is a systemic allergic reaction driven by a massive release of mediators like histamine from mast cells.
Evaluate the primary effects of these mediators: they cause bronchoconstriction (airway narrowing) and widespread vasodilation (blood vessel widening).
Connect the pathophysiology to the options: Bronchoconstriction directly causes wheezing. Vasodilation directly causes hypotension (not hypertension).
Consider secondary effects: The body responds to hypotension with compensatory tachycardia. Anuria is a very late complication of organ failure from prolonged shock.
Compare the valid signs: Both wheezing and tachycardia are expected. However, wheezing is a direct, primary consequence of the allergic process in the airways, making it a more specific and 'typical' diagnostic feature of anaphylaxis than the general compensatory response of tachycardia.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 716-718

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 1448-1450, 650-652