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Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition.

Wang FT, Chan HL, Wang CL, Jian HM, Lin SH - Sensors (Basel) (2015)

Bottom Line: This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring.Moreover, large motion artifacts disable the EMD to decompose respiratory components.A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Hwa Hsia University of Technology, 111, Gongzhuan Rd., Zhonghe, New Taipei City 23568, Taiwan. wft.intuitive@seed.net.tw.

ABSTRACT
Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD) can decompose a signal into several intrinsic mode functions (IMFs) that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method.

No MeSH data available.


Related in: MedlinePlus

Three thoracic impedance segments contain motion artifacts caused by various postural changes: (a) sit to supine; (c) supine to left-lateral lying (LLL); and (e) LLL to right-lateral lying (RLL). These movement-induced artifacts cannot be easily removed by digital filtering (a fourth-order anti-causal Butterworth highpass filter with a cutoff frequency of 0.1 Hz and a sixth-order anti-causal Butterworth lowpass filter with a cutoff frequency of 1 Hz). The respirations are still overwhelmed by motion artifacts, which may be regarded as respirations (b,d,f).
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sensors-15-16372-f001: Three thoracic impedance segments contain motion artifacts caused by various postural changes: (a) sit to supine; (c) supine to left-lateral lying (LLL); and (e) LLL to right-lateral lying (RLL). These movement-induced artifacts cannot be easily removed by digital filtering (a fourth-order anti-causal Butterworth highpass filter with a cutoff frequency of 0.1 Hz and a sixth-order anti-causal Butterworth lowpass filter with a cutoff frequency of 1 Hz). The respirations are still overwhelmed by motion artifacts, which may be regarded as respirations (b,d,f).

Mentions: During ambulatory recording, sudden or large upper-body movement usually disturbs the sensing of thoracic expansion and distraction. As shown in Figure 1, the measured thoracic impedance is overwhelmed by large artifacts. The movement-induced artifact cannot be easily removed by digital filtering; moreover, the filtering creates a pseudo-respiration problem.


Instantaneous Respiratory Estimation from Thoracic Impedance by Empirical Mode Decomposition.

Wang FT, Chan HL, Wang CL, Jian HM, Lin SH - Sensors (Basel) (2015)

Three thoracic impedance segments contain motion artifacts caused by various postural changes: (a) sit to supine; (c) supine to left-lateral lying (LLL); and (e) LLL to right-lateral lying (RLL). These movement-induced artifacts cannot be easily removed by digital filtering (a fourth-order anti-causal Butterworth highpass filter with a cutoff frequency of 0.1 Hz and a sixth-order anti-causal Butterworth lowpass filter with a cutoff frequency of 1 Hz). The respirations are still overwhelmed by motion artifacts, which may be regarded as respirations (b,d,f).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541883&req=5

sensors-15-16372-f001: Three thoracic impedance segments contain motion artifacts caused by various postural changes: (a) sit to supine; (c) supine to left-lateral lying (LLL); and (e) LLL to right-lateral lying (RLL). These movement-induced artifacts cannot be easily removed by digital filtering (a fourth-order anti-causal Butterworth highpass filter with a cutoff frequency of 0.1 Hz and a sixth-order anti-causal Butterworth lowpass filter with a cutoff frequency of 1 Hz). The respirations are still overwhelmed by motion artifacts, which may be regarded as respirations (b,d,f).
Mentions: During ambulatory recording, sudden or large upper-body movement usually disturbs the sensing of thoracic expansion and distraction. As shown in Figure 1, the measured thoracic impedance is overwhelmed by large artifacts. The movement-induced artifact cannot be easily removed by digital filtering; moreover, the filtering creates a pseudo-respiration problem.

Bottom Line: This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring.Moreover, large motion artifacts disable the EMD to decompose respiratory components.A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Hwa Hsia University of Technology, 111, Gongzhuan Rd., Zhonghe, New Taipei City 23568, Taiwan. wft.intuitive@seed.net.tw.

ABSTRACT
Impedance plethysmography provides a way to measure respiratory activity by sensing the change of thoracic impedance caused by inspiration and expiration. This measurement imposes little pressure on the body and uses the human body as the sensor, thereby reducing the need for adjustments as body position changes and making it suitable for long-term or ambulatory monitoring. The empirical mode decomposition (EMD) can decompose a signal into several intrinsic mode functions (IMFs) that disclose nonstationary components as well as stationary components and, similarly, capture respiratory episodes from thoracic impedance. However, upper-body movements usually produce motion artifacts that are not easily removed by digital filtering. Moreover, large motion artifacts disable the EMD to decompose respiratory components. In this paper, motion artifacts are detected and replaced by the data mirrored from the prior and the posterior before EMD processing. A novel intrinsic respiratory reconstruction index that considers both global and local properties of IMFs is proposed to define respiration-related IMFs for respiration reconstruction and instantaneous respiratory estimation. Based on the experiments performing a series of static and dynamic physical activates, our results showed the proposed method had higher cross correlations between respiratory frequencies estimated from thoracic impedance and those from oronasal airflow based on small window size compared to the Fourier transform-based method.

No MeSH data available.


Related in: MedlinePlus