Letter: Artificial sighs.
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D006801:Humans; D008875:Middle Aged; D012121:Respiration, Artificial; D013147:Spirometry; D012122:Ventilators, Mechanical / Q000295:instrumentation*; D014797:Vital Capacity