title: The airflow resistance sensing threshold during tidal breathing rises in old age in patients with asthma.
abstract: BACKGROUND
  in a previous study, we showed that the ability to detect a rise in airflow resistance at rest was reduced in some non-asthmatic subjects in old age.
  
  
  OBJECTIVE
  to determine whether airflow resistance detection is attenuated in elderly subjects with asthma.
  
  
  METHODS
  we studied 60 adult subjects with stable asthma (age range 20-88). Progressive external airflow resistance loading was used to measure the inspiratory load detection threshold (LDT) during tidal breathing at rest.
  
  
  RESULTS
  the mean inspiratory LDT was 5.57 (4.33 SD) kPa.s/l in the 20-64 age group (n=32) and 15.6 (10.1 SD) kPa.s/l in those aged 65 and above (n=28) (P<0.0001). The inspiratory LDT was significantly correlated with age (r=0.5246, P<0.00008), mainly due to the effect of higher LDTs in about half of the subjects above the age of 65 years. Expiratory LDT values and correlations were very similar to inspiratory values.
  
  
  CONCLUSIONS
  the threshold for detecting external resistive loads during tidal breathing rises in old age in some, but not all, asthmatic patients as was observed in non-asthmatic subjects. The finding has implications for treatment guidelines because some elderly subjects are likely to have reduced awareness of worsening airflow obstruction, and consequently delay their use of rescue treatments.
authors.affiliation: Medicine and Geriatrics, Royal Bournemouth Hospital, Castle Lane East, Bournemouth BH7 7DW, UK. stephen.allen@rbch.nhs.uk
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Allen
authors.forename: Ahmed
authors.initials: A
authors.lastname: Khattab
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000403:Airway Resistance / Q000187:drug effects; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D001364:Awareness; D001993:Bronchodilator Agents / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D004739:England; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D001239:Inhalation / Q000187:drug effects; D008168:Lung / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011434:Proprioception; D011446:Prospective Studies; D012684:Sensory Thresholds; D013147:Spirometry; D014797:Vital Capacity; D055815:Young Adult
chemical_list: D001993:Bronchodilator Agents