Figure 1. Comparison of the proportion of the fall in FEV1 during methacholine challenge that is due to airway closure prior to bariatric surgery.
The Closing Index, calculated as the % fall in FVC/ % fall in FEV1 at the highest dose of the methacholine challenge, was compared between obese non-asthmatic, obese asthmatics with elevated serum IgE (TH2-high) and obese asthmatics with normal serum IgE (TH2-low). A larger closing index represents a greater proportion of overall bronchoconstriction attributed to airway closure. The mean± SEM closing index in normal weight non-asthmatics is 0.54 ± 0.03 (9). ns = non-significant ANOVA.