Institute of Clinical Science, University of Bergen, Bergen, Norway Dept of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway
Clinical Science Centre, University Hospital Aintree, Liverpool, UK.
Eur Respir J. 2015 Mar;45(3):625-34. doi: 10.1183/09031936.00051214. Epub 2014 Oct 30.
The forced oscillation technique can identify expiratory flow limitation (EFL) when a large difference in inspiratory and expiratory reactance (ΔXrs) occurs. However, flow limitation can vary from breath to breath, and so we compared a multiple-breath ΔXrs approach to the traditional breath-by-breath assessment of EFL. We investigated the within- and between-day reproducibility and the factors that affect the size of ΔXrs when used as a continuous measurement over multiple breaths. In addition, we examined how multiple-breath ΔXrs relates to the sensation of breathlessness. 425 moderate to very severe chronic obstructive pulmonary disease (COPD) patients and 229 controls were included. Spirometry and impedance measurements were performed on a MasterScope CT Impulse Oscillation System. Median ΔXrs approached zero in healthy controls with little variation between measurements. COPD patients generally had higher ΔXrs and higher variability. The COPD patients with ΔXrs >0.1 kPa · L(-1) · s(-1) were prone to be more breathless and had a higher modified Medical Research Council dyspnoea scale score. In controls, the 95th percentile of ΔXrs was as low as 0.07 kPa · L(-1) · s(-1). We describe a new method to assess EFL at a patient level and propose a cut-off, mean ΔXrs >0.1 kPa · L(-1) · s(-1), as a way to identify COPD patients who are more likely to report dyspnoea.
强迫振荡技术可在吸气和呼气电抗（ΔXrs）之间出现较大差异时识别呼气流量受限（EFL）。然而，流量限制可能会随呼吸而变化，因此我们比较了多呼吸ΔXrs 方法与传统的逐次呼吸 EFL 评估。我们研究了在多呼吸时作为连续测量时的日内和日间重现性，以及影响ΔXrs 大小的因素。此外，我们还检查了多呼吸ΔXrs 与呼吸困难感觉之间的关系。纳入了 425 名中度至重度慢性阻塞性肺疾病（COPD）患者和 229 名对照者。在 MasterScope CT 脉冲振荡系统上进行了肺量测定和阻抗测量。健康对照者的中位ΔXrs 接近零，测量之间的变化很小。COPD 患者通常具有更高的ΔXrs 和更高的变异性。ΔXrs>0.1 kPa·L(-1)·s(-1)的 COPD 患者更容易出现呼吸困难，并且改良医学研究委员会呼吸困难量表评分更高。在对照者中，ΔXrs 的第 95 百分位数低至 0.07 kPa·L(-1)·s(-1)。我们描述了一种新的方法来评估患者水平的 EFL，并提出了一个截断值，即平均ΔXrs>0.1 kPa·L(-1)·s(-1)，以识别更有可能报告呼吸困难的 COPD 患者。
