What are the stages of blood gas progression in status asthmaticus?

Updated: Jun 17, 2020
  • Author: Constantine K Saadeh, MD; Chief Editor: John J Oppenheimer, MD  more...
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The 4 stages of blood gas progression in persons with status asthmaticus are as follows:

  • Stage 1 - Characterized by hyperventilation with a normal partial pressure of oxygen (PO2)

  • Stage 2 - Characterized by hyperventilation accompanied by hypoxemia (ie, a low partial pressure of carbon dioxide [PCO2] and low PO2)

  • Stage 3 - Characterized by the presence of a false-normal PCO2; ventilation has decreased from the hyperventilation present in the second stage; this is an extremely serious sign of respiratory muscle fatigue that signals the need for more intensive medical care, such as admission to an ICU and, probably, intubation with mechanical ventilation.

  • Stage 4 - Characterized by a low PO2 and a high PCO2, which occurs with respiratory muscle insufficiency; this is an even more serious sign that mandates intubation and ventilatory support.

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