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Difficulty: MediumPhysiological Adaptation

A nurse is caring for a client experiencing a severe asthma exacerbation. The client is highly agitated, visibly using accessory muscles to breathe, and has a respiratory rate of 34 breaths/min34 \text{ breaths/min} and a heart rate of 118 beats/min118 \text{ beats/min}. The most recent arterial blood gas (ABG) results on room air are:

ParameterValue
pH7.367.36
PaCO2\text{PaCO}_244 mm Hg44 \text{ mm Hg}
HCO3−\text{HCO}_3^-24 mEq/L24 \text{ mEq/L}
PaO2\text{PaO}_264 mm Hg64 \text{ mm Hg}

Based on these findings, which of the following is the priority nursing action?

  1. A
    Document the arterial blood gas results as they are currently within normal physiological limits.
  2. B
    Administer a rapid bolus of isotonic intravenous fluids to address early signs of hypovolemic shock.
  3. Prepare the client for immediate endotracheal intubation and mechanical ventilation.Answer
  4. D
    Administer a prescribed intravenous sedative to help decrease the client's respiratory rate and agitation.

Answer

Prepare the client for immediate endotracheal intubation and mechanical ventilation.
During a severe asthma exacerbation, a client typically hyperventilates, which blows off carbon dioxide and initially leads to respiratory alkalosis (low PaCO2\text{PaCO}_2). If the client remains in severe distress with a high respiratory rate, but the PaCO2\text{PaCO}_2 level has risen to a 'normal' range (35−45 mm Hg35-45 \text{ mm Hg}), this phenomenon is known as pseudonormalization. It indicates severe respiratory muscle fatigue; the client can no longer maintain the extreme work of breathing. This is a classic sign of impending respiratory arrest, making immediate airway securement via intubation the absolute priority.

Step-by-Step Solution

1
Analyze the client's clinical presentation.
The client is exhibiting severe respiratory distress with a respiratory rate of 34 breaths/min34 \text{ breaths/min}, accessory muscle use, and significant agitation.
Clinical assessment provides the crucial context needed to accurately interpret laboratory values.
2
Evaluate the arterial blood gas (ABG) results in relation to the clinical picture.
The ABG values appear numerically normal, but a severely tachypneic client should have a low PaCO2\text{PaCO}_2 due to hyperventilation (blowing off carbon dioxide).
Identifying the discrepancy between the expected ABG results (respiratory alkalosis) and actual results ('normal' PaCO2\text{PaCO}_2) is essential for detecting physiological decompensation.
3
Determine the physiological cause of the 'normalizing' PaCO2\text{PaCO}_2.
The rising PaCO2\text{PaCO}_2 indicates that the client's respiratory muscles are fatiguing and they can no longer maintain the work of breathing necessary to eliminate carbon dioxide.
Recognizing muscle fatigue leads to the conclusion that respiratory arrest is imminent.
4
Select the priority nursing intervention.
The immediate priority is to collaborate with the healthcare provider to secure the airway via endotracheal intubation and initiate mechanical ventilation.
Airway management takes precedence over all other interventions in a client with impending respiratory failure.

Key Concept

During a severe asthma exacerbation, a 'normal' or rising PaCO2 in the presence of severe tachypnea and increased work of breathing indicates respiratory muscle fatigue and impending respiratory failure.
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Topics

Physiological Adaptation

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