TY - JOUR T1 - Increased airway closure is a determinant of airway hyperresponsiveness JF - European Respiratory Journal JO - Eur Respir J SP - 1563 LP - 1569 DO - 10.1183/09031936.00114007 VL - 32 IS - 6 AU - D. G. Chapman AU - N. Berend AU - G. G. King AU - C. M. Salome Y1 - 2008/12/01 UR - http://erj.ersjournals.com/content/32/6/1563.abstract N2 - In order to investigate whether increased airway closure is a component of airway hyperresponsiveness (AHR), airway closure was compared during induced bronchoconstriction in 62 asthmatic, 41 nonasthmatic nonobese (control) and 20 nonasthmatic obese (obese) subjects. Airway closure and airway narrowing were measured by spirometry as percentage change in forced vital capacity (%ΔFVC) and change in forced expiratory ratio (ΔFER), respectively. Multiple regression analyses were used to assess the determinants of AHR, assessed by the dose response slope (DRS). The DRS was significantly increased in asthmatics compared with controls but did not differ between obese and controls. The spirometric predictors of logDRS were baseline FER, ΔFER, body mass index (BMI) and %ΔFVC. There was a negative relationship between BMI and logDRS in the regression, suggesting a protective effect. The present findings suggest that the extent of airway closure during induced bronchoconstriction is a determinant of airway hyperresponsiveness, independent of the level of airway narrowing. However, after adjusting for airway closure, obesity appears to protect against airway hyperresponsiveness. ER -