Background Mucociliary clearance (MCC) is critical to lung health and is impaired in many diseases. The path of MCC may have an important impact on clearance but has never been rigorously studied. The objective of this study is to assess the three-dimensional path of human tracheal MCC in disease and health. Methods Tracheal MCC was imaged in 12 ex-smokers, 3 non-smokers (1 opportunistically imaged during acute influenza and repeated after recovery) and 5 individuals with primary ciliary dyskinesia (PCD). Radiolabelled macroaggregated albumin droplets were injected into the trachea via the cricothyroid membrane. Droplet movement was tracked via scintigraphy, the path of movement mapped and helical and axial models of tracheal MCC were compared. Measurements and main results In 5/5 participants with PCD and 1 healthy participant with acute influenza, radiolabelled albumin coated the trachea and did not move. In all others (15/15), mucus coalesced into globules. Globule movement was negligible in 3 ex-smokers, but in all others (12/15) ascended the trachea in a helical path. Median cephalad tracheal MCC was 2.7 mm/min ex-smokers vs 8.4 mm/min non-smokers (p=0.02) and correlated strongly to helical angle (r=0.92 (p=0.00002); median 18o ex-smokers, 47o non-smokers (p=0.036)), but not to actual speed on helical path (r=0.26 (p=0.46); median 13.6 mm/min ex-smokers vs 13.9 mm/min non-smokers (p=1.0)). Conclusion For the first time, we show that human tracheal MCC is helical, and impairment in ex-smokers is often caused by flattened helical transit, not slower movement. Our methodology provides a simple method to map tracheal MCC and speed in vivo. Data are available on reasonable request.

中文翻译：

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粘液以螺旋形式从气管中清除：了解气道疾病的新转折

背景 粘液纤毛清除（MCC）对于肺部健康至关重要，并且在许多疾病中都会受到损害。MCC 的路径可能对清除产生重要影响，但从未经过严格研究。本研究的目的是评估人类气管 MCC 在疾病和健康中的三维路径。方法 对 12 名戒烟者、3 名非吸烟者（其中 1 名在急性流感期间机会性成像并在康复后重复进行）和 5 名原发性纤毛运动障碍 (PCD) 患者进行了气管 MCC 成像。将放射性标记的大聚集白蛋白液滴通过环甲膜注入气管。通过闪烁扫描技术跟踪液滴运动，绘制运动路径，并比较气管 MCC 的螺旋和轴向模型。测量和主要结果 在 5/5 患有 PCD 的参与者和 1 名患有急性流感的健康参与者中，放射性标记白蛋白覆盖气管并且不移动。在所有其他情况下（15/15），粘液凝聚成小球。在 3 名戒烟者中，小球运动可以忽略不计，但在所有其他人 (12/15) 中，小球运动以螺旋路径上升到气管。戒烟者头侧气管 MCC 中位数为 2.7 毫米/分钟，非吸烟者为 8.4 毫米/分钟 (p=0.02)，与螺旋角密切相关 (r=0.92 (p=0.00002)；戒烟者中位为 18°，非吸烟者为 47°吸烟者 (p=0.036))，但不是螺旋路径上的实际速度 (r=0.26 (p=0.46)；戒烟者中位数 13.6 毫米/分钟 vs 不吸烟者 13.9 毫米/分钟 (p=1.0)）。结论 我们首次证明人类气管 MCC 是螺旋形的，戒烟者的损伤通常是由扁平的螺旋传输引起的，而不是较慢的运动引起的。我们的方法提供了一种简单的方法来绘制体内气管 MCC 和速度。可根据合理要求提供数据。