Department of Respiratory Medicine, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.
Department of Respiratory Medicine, Zhongshan Hospital, Fudan University, Shanghai, China.
Respirology. 2017 Apr;22(3):527-532. doi: 10.1111/resp.12950. Epub 2016 Nov 29.
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 β for characterization of the start to the MEFV curve.
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 β between the tangent line and x-axis was obtained. The relationships between tangent of β, 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.
In 998 subjects with high-quality spirometry, although PFP varied in relation to the three aspects: the angle β and its tangent were similar (P > 0.05), the tangent of β did not correlate with PFP or anthropometric measurements (P > 0.05) and the lower limit of normal (LLN) of the angle β was 80° in the group with high-quality spirometry (P < 0.05). Angle β derived from poor-quality MEFV curves was smaller than that from good quality one (P < 0.05).
Angle β may function as a parameter to assess the expiratory efforts, which can be used to assess the quality of the MEFV curve start.
美国胸科学会（ATS）和欧洲呼吸学会（ERS）强调最大呼气流量-容积（MEFV）曲线有一个满意的起始，并强调主观参数：无犹豫地完成呼气且用最大力量呼气。我们描述了一个新的参数β，用于描述 MEFV 曲线的起始。
受试者至少完成三次 MEFV 曲线，且至少两条曲线符合 ATS/ERS 质量标准。根据肺功能测试结果，将受试者分为正常、限制和阻塞组。在 MEFV 曲线上升支的起始处绘制切线至 x 轴，得到切线与 x 轴之间的角度β。评估β切线与肺功能参数（PFPs）和人体测量数据之间的关系。将起始处呼气不足的 MEFV 曲线视为质量差的 MEFV 曲线。
在 998 例高质量肺功能的受试者中，尽管 PFP 与三个方面有关，但β角及其切线相似（P＞0.05），β切线与 PFP 或人体测量值不相关（P＞0.05），高质量肺功能组中β角的正常下限（LLN）为 80°（P＜0.05）。质量差的 MEFV 曲线的β角小于质量好的 MEFV 曲线的β角（P＜0.05）。
β角可以作为评估呼气努力的参数，用于评估 MEFV 曲线起始的质量。
