The Edmond and Lili Safra Children's Hospital, Sheba Medical Center, Ramat-Gan, Affiliated with Sackler Medical School, Tel-Aviv, Israel.
Respir Med. 2013 Jul;107(7):975-80. doi: 10.1016/j.rmed.2013.03.012. Epub 2013 May 8.
The forced expiratory decay in healthy preschool children portrays a convex shape that differs from the linear decay in the older healthy population. The "adult-type" expiratory decay during airway obstruction is concave. The study objective was to determine if the expiratory decay in young asthmatic children is "adult-type".
Among 245 children (age 3-7 yrs), 178 had asthma (asthmatics) and 67 were non-asthmatic (controls). The expiratory flow decay was inspected by FEF25-75/FVC ratio (=1.0 when linear). Values were compared to those of our formerly studied (n = 108) healthy children. A meaningful obstruction in FEF25-75/FVC ratio was defined as 2-zScores from healthy. A meaningful response to bronchodilators was related to non-asthmatics.
In healthy subjects FEF25-75/FVC ratio declined with age from 1.73 ± 0.17 to 1.28 ± 0.11. Non-asthmatics portrayed ratio values similar to those of healthy subjects. In asthmatics, 118/178 displayed a convex to linear expiratory decay (FEF25-75/FVC = 1.33 ± 0.22). Sixty/178 asthmatics portrayed concavity (FEF25-75/FVC-0.79 ± 0.16) that appeared when FEF50 was 43.4 ± 12%healthy. Concavity appearance was also age-dependent (30.4% of 3-4 y old and 59.1% of 6-7 y). Vital-Capacity decreased in either decays, forming a visually petit curve. Most asthmatic children respond to bronchodilators by a meaningful elevation in FEF25-75/FVC values and by a visual change in the shape of the curve. Other common spirometry indices also increased meaningfully.
Most asthmatic preschool children portray convex to linear expiratory decay with diminished vital-capacity, resulting in a visually smaller than healthy curve, with seemingly normal expiratory decay. These curves may be misinterpreted as "normal" or as "no-cooperation" and may lead to misinterpretation. In response to bronchodilators, FEF25-75/FVC value increases in asthmatics and the curve changes from concave to linear or from linear to convex contour.
健康学龄前儿童的用力呼气衰减呈现出凸形，与老年健康人群的线性衰减不同。气道阻塞时的“成人型”呼气衰减为凹形。本研究旨在确定年轻哮喘儿童的呼气衰减是否为“成人型”。
在 245 名儿童（3-7 岁）中，178 名为哮喘患儿（哮喘组），67 名非哮喘患儿（对照组）。通过 FEF25-75/FVC 比值（当线性时为 1.0）检查呼气流量衰减。将这些值与我们之前研究的 108 名健康儿童进行比较。将 FEF25-75/FVC 比值的有意义的阻塞定义为与健康儿童相比相差 2-z 个标准差。支气管扩张剂的有意义反应与非哮喘儿童有关。
在健康受试者中，FEF25-75/FVC 比值随年龄从 1.73±0.17 下降至 1.28±0.11。非哮喘患儿的比值与健康受试者相似。在哮喘患儿中，118/178 显示出凸形到线性的呼气衰减（FEF25-75/FVC=1.33±0.22）。60/178 名哮喘患儿表现出凹形（FEF25-75/FVC-0.79±0.16），当 FEF50 为 43.4±12%健康时出现。凹形出现也与年龄相关（30.4%的 3-4 岁和 59.1%的 6-7 岁）。两种衰减均使肺活量降低，形成视觉上较小的曲线。大多数哮喘患儿通过 FEF25-75/FVC 值的有意义升高和曲线形状的视觉变化对支气管扩张剂有反应。其他常见的肺活量指数也有显著增加。
大多数哮喘学龄前儿童表现出凸形到线性的呼气衰减，肺活量降低，导致曲线比健康曲线视觉上更小，呼气衰减看似正常。这些曲线可能被误解为“正常”或“不合作”，并可能导致误解。支气管扩张剂治疗后，哮喘患儿的 FEF25-75/FVC 值增加，曲线从凹形变为线性或从线性变为凸形。
