Department of Pulmonology, University Children's Hospital of Nancy, Nancy, France.
DevAH, Université de Lorraine, Nancy, France.
Pediatr Pulmonol. 2021 Jan;56(1):226-233. doi: 10.1002/ppul.25162. Epub 2020 Nov 19.
Asthma assessment by spirometry is challenging in children as forced expiratory volume in 1 s (FEV1) is frequently normal at baseline. Bronchodilator (BD) reversibility testing may reinforce asthma diagnosis but FEV1 sensitivity in children is controversial. Ventilation inhomogeneity, an early sign of airway obstruction, is described by the upward concavity of the descending limb of the forced expiratory flow-volume loop (FVL), not detected by FEV1. The aim was to test the sensitivity and specificity of FVL shape indexes as β-angle and forced expiratory flow at 50% of the forced vital capacity (FEF50)/peak expiratory flow (PEF) ratio, to identify asthmatics from healthy children in comparison to "usual" spirometric parameters. Seventy-two school-aged asthmatic children and 29 controls were prospectively included. Children performed forced spirometry at baseline and after BD inhalation. Parameters were expressed at baseline as z-scores and BD reversibility as percentage of change reported to baseline value (Δ%). Receiver operating characteristic curves were generated and sensitivity and specificity at respective thresholds reported. Asthmatics presented significantly smaller zβ-angle, zFEF50/PEF and zFEV1 (p ≤ .04) and higher BD reversibility, significant for Δ%FEF50/PEF (p = .02) with no difference for Δ%FEV1. zβ-angle and zFEF50/PEF exhibited better sensitivity (0.58, respectively 0.60) than zFEV1 (0.50), and similar specificity (0.72). Δ%β-angle showed higher sensitivity compared to Δ%FEV1 (0.72 vs. 0.42), but low specificity (0.52 vs. 0.86). Quantitative and qualitative assessment of FVL by adding shape indexes to spirometry interpretation may improve the ability to detect an airway obstruction, FEV1 reflecting more proximal while shape indexes peripheral bronchial obstruction.
肺量测定评估哮喘在儿童中具有挑战性，因为 1 秒用力呼气量（FEV1）在基线时通常正常。支气管扩张剂（BD）可逆性测试可能会加强哮喘诊断，但儿童的 FEV1 敏感性存在争议。通气不均一性是气道阻塞的早期迹象，其表现为用力呼气流量 - 容积环（FVL）下降支的上凹形，而 FEV1 无法检测到。目的是测试 FVL 形状指数（β角和用力呼出 50%肺活量时的流量与峰值呼气流速的比值，FEF50/PEF）的敏感性和特异性，以识别与“常规”肺量测定参数相比，哮喘患儿和健康儿童。前瞻性纳入 72 名学龄期哮喘儿童和 29 名对照者。儿童在基线和 BD 吸入后进行强制肺活量测定。参数以基线时的 z 分数表示，BD 反应性以相对于基线值的变化百分比（Δ%）表示。生成受试者工作特征曲线，并报告相应阈值的敏感性和特异性。哮喘患儿的 zβ角、zFEF50/PEF 和 zFEV1 显著较小（p≤0.04），BD 反应性显著更高，Δ%FEF50/PEF 差异有统计学意义（p=0.02），而Δ%FEV1 无差异。zβ角和 zFEF50/PEF 的敏感性（分别为 0.58 和 0.60）优于 zFEV1（0.50），特异性相似（0.72）。与Δ%FEV1（0.72 比 0.42）相比，Δ%β角显示出更高的敏感性，但特异性较低（0.52 比 0.86）。通过将形状指数添加到肺量测定解释中，对 FVL 进行定量和定性评估可能会提高检测气道阻塞的能力，FEV1 反映更近端的阻塞，而形状指数则反映外周支气管阻塞。
