Bossé Ynuk
Institut Universitaire de Cardiologie et de Pneumologie de Québec-Université Laval, Québec, QC, Canada.
Front Physiol. 2022 Sep 20;13:978332. doi: 10.3389/fphys.2022.978332. eCollection 2022.
Metrics used in spirometry caught on in respiratory medicine not only because they provide information of clinical importance but also because of a keen understanding of what is being measured. The forced expiratory volume in 1 s (FEV), for example, is the maximal volume of air that can be expelled during the first second of a forced expiratory maneuver starting from a lung inflated to total lung capacity (TLC). Although it represents a very gross measurement of lung function, it is now used to guide the diagnosis and management of many lung disorders. Metrics used in oscillometry are not as concrete. Resistance, for example, has several connotations and its proper meaning in the context of a lung probed by an external device is not always intuitive. I think that the popularization of oscillometry and its firm implementation in respiratory guidelines starts with a keen understanding of what exactly is being measured. This review is an attempt to clearly explain the basic metrics of oscillometry. In my opinion, the fundamentals of oscillometry can be understood using a simple example of an excised strip of lung tissue subjected to a sinusoidal strain. The key notion is to divide the sinusoidal reacting force from the tissue strip into two sinusoids, one in phase with the strain and one preceding the strain by exactly a quarter of a cycle. Similar notions can then be applied to a whole lung subjected to a sinusoidal flow imposed at the mouth by an external device to understand basic metrics of oscillometry, including resistance, elastance, impedance, inertance, reactance and resonant frequency.
肺量计中使用的指标在呼吸医学中流行起来，不仅是因为它们提供了具有临床重要性的信息，还因为对所测量的内容有深刻的理解。例如，一秒用力呼气量（FEV）是指从肺充气至肺总量（TLC）开始的用力呼气动作的第一秒内能够呼出的最大空气量。尽管它只是对肺功能的一个非常粗略的测量，但现在它被用于指导许多肺部疾病的诊断和管理。振荡法中使用的指标则不那么具体。例如，阻力有多种含义，在外部设备探测肺部的情况下，其确切含义并不总是直观的。我认为，振荡法的普及及其在呼吸指南中的稳固应用始于对所测量的究竟是什么有深刻的理解。这篇综述试图清晰地解释振荡法的基本指标。在我看来，振荡法的基本原理可以通过一个简单的例子来理解，即一条切除的肺组织条带受到正弦应变。关键概念是将来自组织条带的正弦反应力分为两个正弦波，一个与应变同相，另一个比应变超前正好四分之一个周期。然后可以将类似的概念应用于整个肺部，该肺部受到外部设备在口腔施加的正弦气流作用，以理解振荡法的基本指标，包括阻力、弹性、阻抗、惯性、电抗和共振频率。
