Mild to moderate hypoxia, which could happen during severe asthma exacerbation (McFadden & Jr. Lyons, 1968 Tai & Read, 1967). could depress the central nervous system and damage cognitive function (Berry et al. 1989), and thus affect doctors' and nurses' assessment on the degree of obstruction (Eckert et al, 2004), and airway delay treatment and increase risk of asthma death Eckert et al. 2004). oxygen therapy is one of the treatments for severe asthmatic exacerbation, however, o therapy was not given to Miss L to prevent her from developing hypoca because she was able to maintain Spo, of 96% on room air. Nevertheless, it was important for the nurses to monitor her oxygen saturation dosely