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Difficulty: MediumPhysiological Adaptation

A nurse is caring for a client admitted to the emergency department with a severe asthma exacerbation. Initially, the client was tachypneic with a respiratory rate of 34 breaths/min, and the initial arterial blood gas (ABG) revealed a pH of 7.50, PaCO2 of 28 mm Hg, and PaO2 of 72 mm Hg. Two hours after receiving continuous nebulized bronchodilators and intravenous corticosteroids, the client remains diaphoretic, is using accessory muscles to breathe, and has significantly diminished breath sounds bilaterally. A repeat ABG shows a pH of 7.38, PaCO2 of 42 mm Hg, and PaO2 of 64 mm Hg. Based on these findings, which of the following is the most accurate interpretation of the client's condition and the priority nursing action?

  1. A
    The client's respiratory alkalosis is resolving, indicating a positive therapeutic response; continue to monitor respiratory status closely.
  2. The client is demonstrating respiratory muscle fatigue and impending respiratory failure; prepare for immediate airway management and intubation.Answer
  3. C
    The client is developing acute metabolic acidosis secondary to the medications; prepare to administer an intravenous sodium bicarbonate infusion.
  4. D
    The client is exhibiting early signs of decompensated shock due to severe hypoxia; anticipate the rapid administration of intravenous vasopressors.

Answer

The client is demonstrating respiratory muscle fatigue and impending respiratory failure; prepare for immediate airway management and intubation.
During an acute asthma exacerbation, clients typically hyperventilate to overcome airway resistance, resulting in a decreased PaCO2 (respiratory alkalosis). If the client continues to exhibit severe distress (accessory muscle use, diaphoresis) and significantly diminished breath sounds (suggesting very little air movement), a PaCO2 that normalizes or rises is an ominous sign. It indicates that the client's respiratory muscles are fatigued, and they are losing the ability to ventilate adequately. This signifies impending respiratory failure, and the priority nursing action is to prepare for immediate intubation and mechanical ventilation to secure the airway and support breathing.

Step-by-Step Solution

1
Analyze the client's clinical presentation.
The client is diaphoretic, using accessory muscles, and has diminished breath sounds.
Clinical signs provide critical context for interpreting diagnostic data. Diminished breath sounds in an asthma exacerbation indicate severely restricted airflow.
2
Interpret the initial and repeat ABG results.
Initial ABG showed respiratory alkalosis (low PaCO2) from hyperventilation. The repeat ABG shows a 'normal' pH and PaCO2, but worsening hypoxemia (lower PaO2).
Comparing trends is essential. In a patient struggling to breathe, a normalizing PaCO2 is a paradoxical finding.
3
Synthesize the clinical and laboratory findings to determine the priority.
The combination of severe respiratory distress and a normalizing PaCO2 means the client can no longer maintain the work of breathing. Impending respiratory failure is occurring.
Recognizing that a 'normal' PaCO2 in the setting of severe asthma is a danger sign ensures timely life-saving interventions.

Key Concept

In severe asthma, a normalizing or elevated PaCO2 combined with continued respiratory distress indicates respiratory muscle fatigue and impending respiratory failure, requiring immediate intubation.
Estimated Time:1m 30s
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Topics

Physiological Adaptation

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