Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany.
Institute of Technical Medicine, Furtwangen University, Villingen-Schwenningen, Germany.
Physiol Meas. 2021 Feb 6;42(1):015008. doi: 10.1088/1361-6579/abdad6.
Current standards for conducting spirometry examinations recommend that the ventilation manoeuvres needed in pulmonary function testing are carried out repeatedly during sessions. Chest electrical impedance tomography (EIT) can determine the presence of ventilation heterogeneity during such manoeuvres, which increases the information content derived from such examinations. The aim of this study was to characterise regional lung function in patients with chronic obstructive pulmonary disease (COPD) during repetitive forced full ventilation manoeuvres. Regional lung function measures derived from these manoeuvres were compared with quiet tidal breathing.
Sixty hospitalised patients were examined during up to three repeated ventilation manoeuvres. Acceptable spirometry manoeuvres were performed and EIT recordings suitable for analysis obtained in 53 patients (12 women, 41 men; age: 68 ± 12 years (mean ± SD)). Pixel values of tidal volume, forced full inspiratory and expiratory volume in 1 s, and forced inspiratory and expiratory vital capacity were calculated from the EIT data. Spatial ventilation heterogeneity was assessed using the coefficient of variation, global inhomogeneity index, and centres and regional fractions of ventilation. Temporal inhomogeneity was determined by examining the pixel expiration times needed to exhale 50% and 75% of regional forced vital capacity.
All EIT-derived measures of regional lung function showed reproducible results during repetitive examinations. Parameters of spatial heterogeneity obtained from quiet tidal breathing were comparable with the measures derived from the forced manoeuvres.
Measures of spatial and temporal ventilation heterogeneity obtained in COPD patients by EIT provide comparable findings during repeated examinations within one testing session. Quiet tidal breathing generates similar information on ventilation heterogeneity as forced manoeuvres that demand a high amount of patient effort.
目前进行肺功能检查的标准建议，在测试过程中需要重复进行通气操作。胸部电阻抗断层成像（EIT）可以在这些操作中确定通气异质性的存在，从而增加此类检查的信息量。本研究旨在描述慢性阻塞性肺疾病（COPD）患者在重复强制全通气操作期间的区域性肺功能。将这些操作得出的区域性肺功能测量值与平静潮气呼吸进行比较。
对 60 名住院患者进行了多达 3 次重复通气操作的检查。在 53 名患者（12 名女性，41 名男性；年龄：68 ± 12 岁（均值 ± 标准差））中进行了可接受的肺功能操作，并获得了适合分析的 EIT 记录。从 EIT 数据中计算了潮气量、1 秒内强制全吸气和呼气量以及强制吸气和呼气肺活量的像素值。使用变异系数、整体不均匀指数以及通气的中心和区域分数来评估空间通气异质性。通过检查呼出区域性强制肺活量的 50%和 75%所需的像素呼气时间来确定时间异质性。
所有 EIT 衍生的区域性肺功能测量值在重复检查中均显示出可重复的结果。从平静潮气呼吸中获得的空间异质性参数与从强制操作中得出的测量值相当。
EIT 在 COPD 患者中获得的空间和时间通气异质性测量值在一次测试过程中的重复检查中提供了可比的结果。平静潮气呼吸产生的通气异质性信息与需要患者大量努力的强制操作相似。
