NCLEX-RN practice › Physiological Adaptation
NCLEX question: rising PaCO2 in an asthma attack
Physiological Adaptation · Multiple choice · Clinical judgment step: Analyze cues
Client record
Trend
| Time | 1300 | 1400 | 1500 |
|---|---|---|---|
| RR (/min) | 32 | 28 | 18 |
| Wheeze | Loud, bilateral | Quieter | Barely audible |
| SpO2 | 90% | 91% | 89% |
| PaCO2 (mm Hg) | 32 | 40 | 52 |
| Speech | Phrases | Words | Unable to speak |
A client is being treated in the emergency department for an acute asthma exacerbation. Which interpretation of the trend is correct?
- A. The client is responding to bronchodilators
- B. The PaCO2 of 40 mm Hg at 1400 is reassuring
- C. The slower respiratory rate shows anxiety has resolved
- D. The client is tiring and developing respiratory failure
Show the answer and rationales
Answer: D
In acute asthma, PaCO2 should be low from hyperventilation. A normal or rising PaCO2, a 'silent chest' and inability to speak indicate respiratory muscle fatigue and impending failure.
- A. Incorrect. Quieter wheeze with falling SpO2 and inability to speak indicates less airflow, not improvement.
- B. Incorrect. A normal PaCO2 in a client with severe asthma who should be hyperventilating is an ominous sign of tiring.
- C. Incorrect. Slowing breathing with rising PaCO2 reflects exhaustion, not calm.
- D. Correct. Correct. A rising PaCO2 (from low to high), falling respiratory rate, quieter breath sounds and inability to speak signal fatigue and impending respiratory arrest. The nurse prepares for airway support.
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