Transthoracic electrical impedance variations associated with respiration

Kira, Shiro; Hukushima, Yasunobu; Kitamura, S; Ito, Ayao

doi:10.1152/jappl.1971.30.6.820

Cited by 33 publications

(6 citation statements)

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“…See text for discussion. respired volume (Kubicek et al 1964, Ashutosh et al 1974, but rather with the current through the lung tissue using a fairly narrow geometrical configuration corresponding to the electrodes through which the current was applied (Kira et al 1971). Hence, inductance belts and TI do not measure the same physical quantity and the expected correlation must be somewhat limited.…”

Section: Discussionmentioning

confidence: 99%

Use of thoracic impedance sensors to screen for sleep-disordered breathing in patients with cardiovascular disease

et al. 2008

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Screening patients for the possibility of sleep apnoea, one of the most common forms of sleep-disordered breathing, requires measurement of respiration. We propose a simple method to estimate the amplitude modulation of a respiratory tidal volume, using a semi-quantitative measure of respiration based on thoracic impedance (TI). Because respiratory volume changes may be accommodated by varying displacements of the rib cage (RC) and abdomen (AB), the latter produced by outward motion of the diaphragm, it is necessary for any useful measure of respiration to be closely related to both RC and AB displacements. Because the relative contributions of RC and AB displacements to respiratory tidal volume vary in different body positions, the present measurements were recorded from subjects in supine, and right and left lateral decubitus postures. We observed a clear linear relationship between TI and both RC and AB signals in all three body positions. There were no statistically significant differences between observed relationships between TI and AB and between TI and RC, and these relationships were independent of the body position. TI sensors appear to be a useful candidate for a simple method of screening for sleep apnoea, especially in a cardiology clinical setting. Further investigation is warranted for the refinement of algorithms to detect changes in amplitude modulation occurring with apnoeas and to remove artefacts due to gross body movements.

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Section: Discussionmentioning

confidence: 99%

Use of thoracic impedance sensors to screen for sleep-disordered breathing in patients with cardiovascular disease

et al. 2008

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“…These quantities can be easily measured non-invasively in real time by transmitting a known low-amplitude and low-frequency current (I) and measuring voltage drop (ΔV) across electrodes attached to the thorax. Numerous studies have shown that change in trans-thoracic impedance as a function of time can be correlated with breathing [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

Prototype development of an electrical impedance based simultaneous respiratory and cardiac monitoring system for gated radiotherapy

et al. 2014

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BackgroundIn radiotherapy, temporary translocations of the internal organs and tumor induced by respiratory and cardiac activities can undesirably lead to significantly lower radiation dose on the targeted tumor but more harmful radiation on surrounding healthy tissues. Respiratory and cardiac gated radiotherapy offers a potential solution for the treatment of tumors located in the upper thorax. The present study focuses on the design and development of simultaneous acquisition of respiratory and cardiac signal using electrical impedance technology for use in dual gated radiotherapy.MethodsAn electronic circuitry was developed for monitoring the bio-impedance change due to respiratory and cardiac motions and extracting the cardiogenic ECG signal. The system was analyzed in terms of reliability of signal acquisition, time delay, and functionality in a high energy radiation environment. The resulting signal of the system developed was also compared with the output of the commercially available Real-time Position Management™ (RPM) system in both time and frequency domains.ResultsThe results demonstrate that the bioimpedance-based method can potentially provide reliable tracking of respiratory and cardiac motion in humans, alternative to currently available methods. When compared with the RPM system, the impedance-based system developed in the present study shows similar output pattern but different sensitivities in monitoring different respiratory rates. The tracking of cardiac motion was more susceptible to interference from other sources than respiratory motion but also provided synchronous output compared with the ECG signal extracted. The proposed hardware-based implementation was observed to have a worst-case time delay of approximately 33 ms for respiratory monitoring and 45 ms for cardiac monitoring. No significant effect on the functionality of the system was observed when it was tested in a radiation environment with the electrode lead wires directly exposed to high-energy X-Rays.ConclusionThe developed system capable of rendering quality signals for tracking both respiratory and cardiac motions can potentially provide a solution for simultaneous dual-gated radiotherapy.

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“…Electrical impedance of biological tissue has been a subject of research for more than 40 y [1,2] with applications ranging from respiratory plethysmography [3] to cardiac stroke volume measurement [4] to detection of bladder cancer [5]. Original bioimpedance analyzers were cumbersome, requiring careful matching of resistors and a large overall number of components.…”

Section: Introductionmentioning

confidence: 99%