How do vital signs change during a severe asthma attack?

Vital signs... In a severe asthma exacerbation, the heart rate increases and the level of oxygen decreases. The blood pressure is variable. If infection is present, there may be a fever. The respiratory rate is high.
Varies. With a severe asthma attack the patients respiratory rate will increase, heart rate may go up. If severe enough to stop breathing then the reverse may occur.