Key result
Head-up tilt position significantly reduced the normalized wavelet biamplitude between respiration and both low and high frequencies of HRV compared to early supine position.
Why the study?
Does the head-up tilt position alter quadratic cardiorespiratory couplings compared to the supine position in young healthy subjects?
Does the head-up tilt position alter quadratic cardiorespiratory couplings compared to the supine position in young healthy subjects?
The proposed real wavelet biphase method robustly detects and quantifies quadratic phase coupling between respiration and HRV, demonstrating significant reductions during head-up tilt.
Answers are grounded in this paper and cite their sources.
May attenuate autonomic cardiorespiratory coupling with posture; leaves open clinical utility beyond healthy subjects.
OBJECTIVE: In this paper, a method for assessment of quadratic phase coupling (QPC) between respiration and heart rate variability (HRV) is presented. METHODS: First, a method for QPC detection is proposed named real wavelet biphase (RWB). Then, a method for QPC quantification is proposed based on the normalized wavelet biamplitude (NWB). A simulation study has been conducted to test the reliability of RWB to identify QPC, even in the presence of constant delays between interacting oscillations, and to discriminate it from quadratic phase uncoupling. Significant QPC was assessed based on surrogate data analysis. Then, quadratic cardiorespiratory couplings were studied during a tilt-table test protocol of 17 young healthy subjects. RESULTS: Simulation study showed that RWB is able to detect even weak QPC with delays in the range of [Formula: see text] s, which are usual in the autonomic nervous system (ANS) control of heart rate. Results from the database revealed a significant reduction ([Formula: see text]) of NWB between respiration and both low and high frequencies of HRV in head-up tilt position compared to early supine. CONCLUSION: The proposed technique detects and quantifies robustly QPC and is able to track the coupling between respiration and various HRV components during ANS changes. SIGNIFICANCE: The proposed method can help to assess alternations of nonlinear cardiorespiratory interactions related to ANS dysfunction and physiological regulation of HRV in cardiovascular diseases.
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Kontaxis et al. (2018) studied Healthy (n=17). Head-up tilt position vs. Early supine position was evaluated on Normalized wavelet biamplitude (NWB) between respiration and both low and high frequencies of HRV. Head-up tilt position significantly reduced the normalized wavelet biamplitude between respiration and both low and high frequencies of HRV compared to early supine position.
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