科研之友
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摘要
Background and objective: The American Thoracic Society (ATS) and European Respiratory Society (ERS) emphasize a satisfactory start in maximal expiratory flow-volume (MEFV) curves and highlight subjective parameters: performance without hesitation and expiration with maximum force. We described a new parameter, angle beta for characterization of the start to the MEFV curve. Methods: Subjects completed the MEFV curve at least three times and at least two curves met ATS/ERS quality. Subjects were divided into normal, restrictive and obstructive groups according to pulmonary function test results. The tangent line was drawn at the start of the MEFV curve's ascending limb to the x-axis and the angle beta between the tangent line and x-axis was obtained. The relationships between tangent of beta, pulmonary function parameters (PFPs) and anthropometric data were assessed. The MEFV curves with insufficient explosion at the start were considered as poor-quality MEFV curves. Results: In 998 subjects with high-quality spirometry, although PFP varied in relation to the three aspects: the angle beta and its tangent were similar (P > 0.05), the tangent of beta did not correlate with PFP or anthropometric measurements (P > 0.05) and the lower limit of normal (LLN) of the angle beta was 80 degrees in the group with high-quality spirometry (P < 0.05). Angle beta derived from poor-quality MEFV curves was smaller than that from good quality one (P < 0.05). Conclusion: Angle beta may function as a parameter to assess the expiratory efforts, which can be used to assess the quality of the MEFV curve start.
