Characterization of airway plugging in fatal asthma.
OBJECTIVE
Case reports suggest that deaths due to asthma can occur without airway plugging. In this study, we examined the hypothesis that obstruction of the airway lumen by an exudate containing mucus and cells is a key feature of fatal asthma attacks.


METHODS
We quantified airway narrowing and lumenal content in 275 airways from 93 patients with fatal asthma aged 10 to 49 years (59 white subjects and 34 Polynesian subjects, including 19 children), compared with airways from control patients who died suddenly without pulmonary diseases.


RESULTS
The severity of lumenal occlusion ranged from 4% to 100% in these cases, but only five airways showed less than 20% occlusion. Compared with controls, patients with asthma had more lumenal occlusion (mean [+/- SD] open lumen, 42% +/- 23% vs. 93% +/- 8%), greater mucus occlusion (28% +/- 13% vs. 5% +/- 6%), and more occlusion by cells (30% +/- 17% vs. 3% +/- 2%, all P<0.0001). Airway narrowing was greater in larger airways (P<0.0001) and older patients (P = 0.009). Greater lumen content was associated with a higher proportion of cells (P = 0.003), and cells made up a higher proportion of the exudate in the small airways (P<0.0001). Lumenal mucus was greater in younger patients with asthma (P = 0.0007) and in Polynesian patients with asthma (P = 0.04).


CONCLUSIONS
Airway lumenal obstruction by an exudate composed of mucus and cells is a major contributing cause of fatal asthma in most patients.
Kuyper
Laura M
LM
University of British Columbia McDonald Research Laboratories, St. Paul's Hospital, Vancouver, British Columbia, Canada.
Paré
Peter D
PD
Hogg
James C
JC
Lambert
Rodney K
RK
Ionescu
Diana
D
Woods
Ryan
R
Bai
Tony R
TR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000150:complications* / Q000453:epidemiology; D001249:Asthma / Q000150:complications* / Q000175:diagnosis*; D001980:Bronchi / Q000378:metabolism; D018929:Cell Culture Techniques; D002648:Child; D006801:Humans; D008875:Middle Aged; D009093:Mucus; D015999:Multivariate Analysis; D012720:Severity of Illness Index