title: The effect of lung stretch during sleep on airway mechanics in overweight and obese asthma.
abstract: Both obesity and sleep reduce lung volume and limit deep breaths, possibly contributing to asthma. We hypothesize that increasing lung volume dynamically during sleep would reduce airway resistance in asthma. Asthma (n=10) and control (n=10) subjects were studied during sleep at baseline and with increased lung volume via bi-level positive airway pressure (BPAP). Using forced oscillations, respiratory system resistance (R(rs)) and reactance (X(rs)) were measured during sleep and R(rs) was partitioned to upper and lower airway resistance (R(up), R(low)) using an epiglottic pressure catheter. R(rs) and R(up) increased with sleep (p<0.01) and X(rs) was decreased in REM (p=0.02) as compared to wake. R(rs), R(up), and R(low), were larger (p<0.01) and X(rs) was decreased (p<0.02) in asthma. On BPAP, R(rs) and R(up) were decreased (p<0.001) and X(rs) increased (p<0.01), but R(low) was unchanged. High R(up) was observed in asthma, which reduced with BPAP. We conclude that the upper airway is a major component of R(rs) and larger lung volume changes may be required to alter R(low).
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, MA, United States. lcampana@bu.edu
authors.forename: L M
authors.initials: LM
authors.lastname: Campana
authors.forename: A
authors.initials: A
authors.lastname: Malhotra
authors.forename: B
authors.initials: B
authors.lastname: Suki
authors.forename: L
authors.initials: L
authors.lastname: Hess
authors.forename: E
authors.initials: E
authors.lastname: Israel
authors.forename: E
authors.initials: E
authors.lastname: Smales
authors.forename: P
authors.initials: P
authors.lastname: Deyoung
authors.forename: R L
authors.initials: RL
authors.lastname: Owens
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology*; D000704:Analysis of Variance; D001249:Asthma / Q000209:etiology*; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D008875:Middle Aged; D018721:Muscarinic Agonists / Q000494:pharmacology; D009765:Obesity / Q000150:complications*; D050177:Overweight / Q000150:complications*; D011175:Positive-Pressure Respiration; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology; D055815:Young Adult
chemical_list: D018721:Muscarinic Agonists; D016210:Methacholine Chloride