Sonography indicators of diaphragm and their correlation with spirometry data in healthy individuals: a prospective study. Annals of Critical Care.

OBJECTIVES: Revealing the correlation between sonography indicators of diaphragm performance and spirometry data of healthy persons in a reclining position.
MATERIAL AND METHODS: The study included in total 50 healthy volunteers (female – 30). The structural and functional indicators of diaphragm (thickness, thickening fraction, excursion, rates during calm and deep inhalation/exhalation) were assessed with the Philips CX50 ultrasound machine (produced by Philips Ultrasound, Inc, USA). The spirometry characteristics were assessed by means of parallel measurement of the tidal volumes during calm and deep breathing with the Bellavista 950e ventilator (Russia, registry number RZN 2021/13644, registration date 31.03 2022) using a mask in the ventilation mode with the constant positive pressure set to 0 cm H2O and the fraction of inspired oxygen set to 21%. The following indicators were assessed: tidal volumes, length of inhalation and exhalation, strength of respiratory muscles.
Mathematical analysis by STATISTICA 10 (StatSoft Inc, USA). The type of data distribution: Kolmogorov-Smirnov test and Shapiro-Wilk test. Spearman correlation analysis with assessment by the Chaddock scale. The descriptive part is presented as the mean and standard deviation (M±SD). The validity of relations was accepted with р ≤0,05.
RESULTS: It was possible to assess the thickness of diaphragm on both sides in all subjects; the diaphragm excursion on the left – only in 20% of subjects. Spirometry has been performed in all subjects. The obtained data are consistent with the literature. In particular, sonography and spirometry indicators of the healthy individuals are within reference values. Inspiratory muscles strength has also proved to be consistent with the literature data. Correlation analysis has revealed no statistically significant relationship between the examined sonography and spirometry parameters. In addition, no relation between age and sonography indicators of diaphragm has been found. There are weak statistically significant relations revealed between the structural and functional state of diaphragm and such anthropometric characteristics of the subjects as body mass and body mass index.
CONCLUSION: Sonography structural and functional indicators of diaphragm performance do not correlate or correlate poorly with spirometry data, i.e. with tidal volumes. There is no reason to use sonography of diaphragm in healthy individuals since it does not practically provide any additional information about the state of external respiratory apparatus. The discrepancy between the sonography indicators of diaphragm function and spirometry data is due to many reasons including the methodological features of the conducted research as well as the apparently unknown contribution of the additional respiratory muscles work and a breathing type.

研究目的：揭示卧位状态下健康人群膈肌功能超声成像（sonography）指标与肺量测定法（spirometry）数据的相关性。
材料与方法：本研究共纳入50名健康志愿者，其中女性30名。采用美国飞利浦超声公司（Philips Ultrasound, Inc, USA）生产的Philips CX50型超声仪评估膈肌结构与功能指标，包括膈肌厚度、增厚分数、移动度，以及平静呼吸与深呼吸时的运动速率。肺量测定法指标则通过以下方式评估：佩戴面罩，在持续气道正压为0 cm H₂O、吸入氧分数为21%的通气模式下，使用俄罗斯产Bellavista 950e型呼吸机（注册编号RZN 2021/13644，注册日期2022年3月31日），同步测量平静呼吸与深呼吸时的潮气量，以此评估相关特征。本次评估指标包括：潮气量、吸气与呼气时长、呼吸肌力量。
采用美国StatSoft公司STATISTICA 10软件进行数据分析。数据分布类型采用柯尔莫哥洛夫-斯米尔诺夫（Kolmogorov-Smirnov）检验与夏皮罗-威尔克（Shapiro-Wilk）检验进行判定。采用斯皮尔曼（Spearman）相关分析，并以查多克（Chaddock）量表进行评估。描述性统计结果以均值±标准差（M±SD）呈现。以p≤0.05作为关联具有统计学意义的判定标准。
结果：所有受试者的双侧膈肌厚度均可被成功评估，但仅20%的受试者可完成左侧膈肌移动度的评估。所有受试者均完成肺量测定法检测。所得数据与文献报道一致：健康人群的超声成像与肺量测定法指标均处于参考值范围内，吸气肌力量也符合文献数据。相关分析结果显示，本次检测的超声成像与肺量测定法参数之间未发现具有统计学意义的相关性。此外，年龄与膈肌超声成像指标之间亦无关联。研究同时发现，膈肌结构与功能状态，与受试者的体重、体质量指数等人体测量学指标之间存在具有统计学意义的弱相关性。
结论：膈肌功能的超声成像结构与功能指标与肺量测定法数据（即潮气量）无相关性，或仅存在微弱相关性。健康人群无需行膈肌超声成像检查，因其几乎无法为外呼吸器官状态提供额外参考信息。膈肌功能超声成像指标与肺量测定法结果存在差异，这可归因于多种因素，包括本研究的方法学特征，以及尚未明确的额外呼吸肌做功与呼吸类型的影响。