Which of the following is an ICU criterion for asthmatics?

• A. Respiratory muscle fatigue or rising CO2
• B. Normal hemodynamics
• C. Normal air movement
• D. Stable mental status

Answer: (A)

Rising CO2 from respiratory muscle fatigue signals that ventilation is failing in an acute asthma attack. As the muscles tire, the patient can no longer blow off enough CO2, leading to hypoventilation and hypercapnia. This is a late and worrisome sign that the patient may deteriorate to respiratory failure, requiring ICU-level monitoring and possible ventilatory support. Other options don’t reflect this collapse of ventilation: normal hemodynamics can occur despite severe airway obstruction, normal air movement suggests adequate airflow, and stable mental status can be maintained early even as fatigue develops, so they aren’t reliable ICU indicators. The key idea is that fatigue with rising CO2 shows the respiratory system isn’t able to meet the body's needs, necessitating ICU care.