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Difficulty: MediumPhysiological Adaptation

A triage nurse in the emergency department is assessing a client who presents with an acute asthma exacerbation. Which of the following clinical findings indicate the client is experiencing impending respiratory failure and requires immediate life-saving intervention? Select all that apply.

  1. Arterial blood gas revealing a pHpH of 7.257.25 and a PaCO2PaCO_2 of 6262 mm HgAnswer
  2. Sudden cessation of wheezing despite visible, labored respiratory effortsAnswer
  3. C
    Loud, continuous expiratory wheezing across all lung fields
  4. D
    Arterial blood gas revealing a pHpH of 7.487.48 and a PaCO2PaCO_2 of 3030 mm Hg
  5. New-onset profound lethargy and inability to maintain eye contactAnswer
  6. F
    Heart rate of 112112 beats/min with a slightly narrowed pulse pressure

Answer

The clinical findings that indicate impending respiratory failure are an arterial blood gas showing respiratory acidosis, the sudden cessation of wheezing, and new-onset profound lethargy.
Impending respiratory failure in an acute asthma exacerbation is characterized by severe air trapping, respiratory muscle fatigue, and poor gas exchange. An arterial blood gas showing respiratory acidosis indicates the client is exhausted and retaining carbon dioxide. A sudden cessation of wheezing (silent chest) is an ominous sign that airflow is too severely restricted to produce sound. Profound lethargy is a late, life-threatening sign of severe hypoxia and hypercapnia, meaning the client is losing the ability to protect their airway and requires immediate mechanical ventilation.

Step-by-Step Solution

1
Analyze the pathophysiology of an acute asthma exacerbation.
Initial bronchospasm causes hyperventilation and respiratory alkalosis. As airway resistance increases over time, respiratory muscles fatigue.
Understanding the trajectory helps distinguish between expected early compensatory signs and ominous late signs of decompensation.
2
Evaluate the arterial blood gas (ABG) options.
A low pH and high carbon dioxide level represent respiratory acidosis, indicating the lungs can no longer expel adequate carbon dioxide.
Respiratory acidosis is a definitive sign of impending failure, whereas early respiratory alkalosis is a typical and expected compensatory mechanism.
3
Assess the physical examination findings.
A 'silent chest' and profound lethargy indicate critical airway closure and severe cerebral hypoxia, respectively, requiring immediate intubation.
While loud wheezing and mild tachycardia are concerning, they indicate the client is still actively moving air and neurologically compensating.

Key Concept

Identifying impending respiratory failure in status asthmaticus
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Topics

Physiological Adaptation

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