Identification of asthmatic subjects with low perception of dyspnea (POD) that are at higher risk of hospitalization, near-fatal and fatal asthma could improve their management.
Objective
Create a simple procedure that facilitate the recognition of low POD.
Methods
We enrolled near fatal asthma (NFA) subjects and a wide spectrum of non-NFA subjects. Each subject was asked to stop breathing at end-expiration. Dyspnea was assesssed by a modified Borg scale. To design the new index, we combined the Borg score at the end of the voluntary breath-holding maneuver with the airway limitation. The equation was as follows: FEV1/FVC%/(breath-holding time in seconds/final Borg score minus basal Borg score).
Results
Eleven NFA subjects (4 females) aged 21–73 yr and 55 non-NFA (14 severe, 18 moderate and 23 mild asthmatic subjects) completed the study. The threshold value of the index that could predict POD is <12. The mean (±sd) of the new index perception was significantly lower in NFA group (n=11; 5.21±3.59; vs. n=55; 13.67±11.08; P=0.006). This threshold value had 100% sensitivity and it best discriminated between mild and NFA groups. The negative likelihood ratio (when the index ⩾12) was zero. A result ⩾12 represented an almost null probability of poor POD.
Conclusion
The breath-holding test is simple and rapid. Its negative likelihood ratio was zero. Accordingly, a test result of 12 or greater might exclude the probability of poor perception of dyspnea in subjects with stable asthma.
This study has been presented as an abstract at the Annual Congress of Argentinean Respiratory Medicine Association in Mendoza, Argentina, 8–11 October 2005.