Can asthma make my CO2 levels low?

Hypocapnia. When you have active asthma, you breathe more rapidly and deeply to make up for low oxygen. In a healthy person, this WILL cause the CO2 to go down . If the attack is severe and the patient starts to have respiratory failure , the CO2 comes back up . This is a very bad sign and means the person probably needs more aggressive management and perhaps mechanical assistance like CPAP or a ventilator. .