Abstract
Risk factors for asthma death were evaluated from pulmonary function tests during stable period. Subjects were divided into three groups. The first group was asthma death group, in which 16 patients(10 males, 6 females) died with acute asthma attacks during last 20 years in our hospital and had performed pulmonary function tests before death, age and duration of asthma being 14.7±4.9 years-old, 12.8±5.9 years(mean±SD) respectively. The second group was severe group, in which 49 patients (29 males, 20 females) had severe asthma attacks with cyanosis between 1988 and 1991 year, and had performed pulmonary function test within one year before such episodes, age and duration of asthma being 15.2±5.2 years-old, 11.9±4.9 years respectively. The third group was mild group, in which 84 patients (56 males, 28 females) under good control, neither had severe attacks nor hospitalization, age and duration of asthma being 13.1±4.4 years-old, 9.6±4.8 years respectively. Pulmonary function tests were performed at 19.7±12.5 months before death in asthma death group and at 4.3±3.8 months before severe attacks in severe group.
The values of FEV1.0% in asthma death group, severe group, and mild group were 67.3±11.3%, 70.0±11.9%, and 81.6±8.0% respectively, while significant lower FEV1.0% were observed in severe group (p<0.05). Significant lower values of %V50 were also observed in asthma death group and severe group, %V50 being 43.6±13.6%, 46.1±21.6% respectively, as compared to mild group (70.5±20.2%). Although mean values of %PEF were within normal range (80-100%) in three groups, being 89.9±27.6%, 89.8±24.3%, and 100.3±21.3% respectively, %PEF was significantly lower in severe group (p<0.05). In six patients who never required hospitalization and steroid treatments during last one year before death in asthma death group, FEV1.0%, %PEF, and %V50 were 74.1±7.1%, 94.7±17.7%, and 49.5±10.2% respectively. Regarding relationship between pulmonary function and duration of asthma, FEV1.0% and %V50 were inversely proportional to duration of asthma in severe group.
These results suggest that measurements of pulmonary function including flow-volume curve are useful in the management of asthma, and that risk of asthma death would be less if their airway obstructions improve without progression.
