Department of Anesthesiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
Department of Anesthesiology, Chiba Emergency Medical Center, Chiba, Japan.
J Appl Physiol (1985). 2023 Jun 1;134(6):1341-1348. doi: 10.1152/japplphysiol.00742.2022. Epub 2023 Apr 20.
Development of reliable noncontact unrestrained respiratory monitoring is capable of augmenting the safety of hospitalized patients in the recovery phase. We previously discovered respiratory-related centroid shifts along the long axis of the bed with load cells under the bed legs [bed sensor system (BSS)]. This prospective exploratory observational study examined whether noncontact measurements of respiratory-related tidal centroid shift amplitude (TA-BSS; primary variable) and respiratory rate (RR-BSS; secondary variable) were correlated with tidal volume (TV-PN) and respiratory rate (RR-PN), respectively, measured by pneumotachograph in 14 ICU patients under mechanical ventilation. Among the 10-min average data automatically obtained for a 48-h period, 14 data samples were randomly selected from each patient. Successfully and evenly selected 196 data points for each variable were used for the purpose of this study. A good agreement between TA-BSS and TV-PN (Pearson's = 0.669) and an excellent agreement between RR-BSS and RR-PN ( = 0.982) were observed. Estimated minute ventilatory volume [3.86 · TA-BSS · RR-BSS (MV-BSS)] was found to be in very good agreement with true minute volume (MV-PN) ( = 0.836). Although Bland-Altman analysis evidenced accuracy of MV-BSS by a small insignificant fixed bias (-0.02 L/min), a significant proportional bias of MV-BSS ( = -0.664) appeared to produce larger precision (1.9 L/min) of MV-BSS. We conclude that contact-free unconstrained respiratory monitoring with load cells under the bed legs may serve as a new clinical monitoring system, when improved. We previously discovered that four load cells placed under the bed legs capture a centroid shift during respiration in bedridden human subjects. In 14 ICU patients under mechanical ventilation, this study evidenced that contact-free measurements of respiratory rate, tidal volume, and minute ventilation with the load cells correlated well with those measured by pneumotachograph. Possible clinical usefulness of this approach as a new clinical respiratory monitor is indicated.
开发可靠的非接触式、无约束的呼吸监测系统可以提高住院患者在康复阶段的安全性。我们之前发现，在床腿下的负载单元下，与呼吸相关的重心沿着床的长轴发生偏移[床传感器系统（BSS）]。这项前瞻性探索性观察研究检验了非接触式测量呼吸相关潮气量重心偏移幅度（TA-BSS；主要变量）和呼吸率（RR-BSS；次要变量）是否与通过气流计测量的潮气量（TV-PN）和呼吸率（RR-PN）分别相关在 14 名接受机械通气的 ICU 患者中。在自动获得的 48 小时期间的 10 分钟平均值数据中，从每位患者中随机选择 14 个数据样本。为了进行这项研究，成功且均匀地为每个变量选择了 196 个数据点。观察到 TA-BSS 与 TV-PN 之间具有良好的一致性（Pearson's = 0.669），RR-BSS 与 RR-PN 之间具有极好的一致性（ = 0.982）。发现估计的分钟通气量[3.86·TA-BSS·RR-BSS（MV-BSS）]与真实分钟通气量（MV-PN）非常吻合（ = 0.836）。尽管 Bland-Altman 分析表明 MV-BSS 的准确性存在小的无统计学意义的固定偏差（-0.02 L/min），但 MV-BSS 存在显著的比例偏差（ = -0.664），这似乎导致 MV-BSS 的精度更高（1.9 L/min）。我们得出结论，改进后，床腿下的负载单元的无接触式无约束呼吸监测可以作为一种新的临床监测系统。我们之前发现，将四个负载单元放置在床腿下，可以在卧床的人体受试者呼吸时捕获重心偏移。在 14 名接受机械通气的 ICU 患者中，这项研究表明，使用负载单元进行的无接触式呼吸率、潮气量和分钟通气量测量与通过气流计测量的结果高度相关。作为一种新的临床呼吸监测器，这种方法可能具有潜在的临床应用价值。
