scholarly journals Bispectral Index™ Alterations Have Associations with Autonomic Changes during Hypnosis in Trauma Center Researchers: A Formative Evaluation (Preprint)

2020 ◽  
Author(s):  
C. Michael Dunham ◽  
Amanda L. Burger ◽  
Barbara M. Hileman ◽  
Elisha A. Chance ◽  
Amy E. Hutchinson
Keyword(s):  
Respiratory Rate ◽  
Skin Conductance ◽  
High Frequency ◽  
Trauma Center ◽  
Formative Evaluation ◽  
Low Frequency ◽  
High Frequency Power ◽  
Interbeat Interval ◽  
Low Frequency Power ◽  
Frequency Power

BACKGROUND Hypnosis was induced to enhance reductions in Bispectral Index™ (BIS) values. OBJECTIVE Autonomic monitoring was used to assess physiologic relaxation and explore their associations with BIS values. METHODS Each session consisted of reading a 4-minute baseline neutral script and playing an 18-minute hypnosis tape to 3 researchers involved in the BIS neurofeedback study. In addition to BIS monitoring, autonomic monitoring was performed and included measures of electromyography, skin temperature, skin conductance, respiratory rate, expired carbon dioxide, and heart rate variability. The t-test, correlation analyses, and multivariate linear regression analyses were used in data analysis. RESULTS Hypnosis was associated with reductions in BIS (P<.001), electromyography (P<.001), respiratory rate (P<.001), skin conductance (P=.006), and very low frequency power (P=.04) and with increases in expired carbon dioxide (P<.001), skin temperature (P=.04), high frequency power (P<.001), and successive heart interbeat interval difference (P=.04) values. Decreased BIS values were associated with reduced electromyography measures (R=.76; P<.001), respiratory rate (R=.35; P=.004), skin conductance (R=.57; P<.001), and low frequency power (R=.32; P=.01) and with increased high frequency power (R=-.53; P<.001), successive heart interbeat interval difference (R=-.32; P=.009), and standard deviation of heart interbeat interval (R=-.26; P=.04) values. CONCLUSIONS Hypnosis appeared to induce mental and physical relaxation, enhance parasympathetic neural activation, and attenuate sympathetic nervous system activity, changes that were associated with BIS values. Findings of the preliminary formative evaluation suggest that the current hypnosis model may be useful for assessing autonomic physiological associations with changes in BIS values, thus motivating us to proceed with a larger investigation in trauma center nurses and physicians. CLINICALTRIAL None

Cardiovascular variability after arousal from sleep: time-varying spectral analysis

2003 ◽  
Vol 95 (4) ◽  
pp. 1394-1404 ◽  
Author(s):  
Anna Blasi ◽  
Javier Jo ◽  
Edwin Valladares ◽  
Barbara J. Morgan ◽  
James B. Skatrud ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
High Frequency ◽  
Low Frequency ◽  
Sleep Time ◽  
Respiratory Pattern ◽  
Time Varying ◽  
High Frequency Power ◽  
Low Frequency Power ◽  
Frequency Power

We performed time-varying spectral analyses of heart rate variability (HRV) and blood pressure variability (BPV) recorded from 16 normal humans during acoustically induced arousals from sleep. Time-varying autoregressive modeling was employed to estimate the time courses of high-frequency HRV power, low-frequency HRV power, the ratio between low-frequency and high-frequency HRV power, and low-frequency power of systolic BPV. To delineate the influence of respiration on HRV, we also computed respiratory airflow high-frequency power, the modified ratio of low-frequency to high-frequency HRV power, and the average transfer gain between respiration and heart rate. During cortical arousal, muscle sympathetic nerve activity and heart rate increased and returned rapidly to baseline, but systolic blood pressure, the ratio between low-frequency and high-frequency HRV power, low-frequency HRV power, the modified ratio of low-frequency to high-frequency HRV power, and low-frequency power of systolic BPV displayed increases that remained above baseline up to 40 s after arousal. High-frequency HRV power and airflow high-frequency power showed concommitant decreases to levels below baseline, whereas the average transfer gain between respiration and heart rate remained unchanged. These findings suggest that 1) arousal-induced changes in parasympathetic activity are strongly coupled to respiratory pattern and 2) the sympathoexcitatory cardiovascular effects of arousal are relatively long lasting and may accumulate if repetitive arousals occur in close succession.

Aging of modulation of heart rate

1987 ◽  
Vol 253 (4) ◽  
pp. H874-H877 ◽  
Author(s):  
D. C. Shannon ◽  
D. W. Carley ◽  
H. Benson
Keyword(s):  
Heart Rate ◽  
Supine Position ◽  
High Frequency ◽  
Low Frequency ◽  
Standing Position ◽  
Total Power ◽  
High Frequency Power ◽  
Sinus Arrhythmia ◽  
Low Frequency Power ◽  
Frequency Power

We postulated that measurements of autonomically mediated fluctuations in heart rate might provide a quantitative probe of biological aging. We used power spectrum analysis of instantaneous heart rate while 33 male subjects matched their breathing to a metronome at 15 breaths/min. Measurements were made in supine and standing position. Total power and its two major components, high- and low-frequency power, declined with age in both positions but at different rates. High-frequency power that represents parasympathetically mediated respiratory sinus arrhythmia declined linearly in supine position only in subjects 9-28 yr with a slope of -0.796, which was significantly different from zero at P = 0.0007. The absolute value of high-frequency power in standing position was approximately 60% of that in supine, a difference that was statistically significant (P = 0.01). Low-frequency power that represents beta-adrenergically mediated heart rate fluctuations, especially in standing position, declined linearly to 62 yr of age (P = 0.0001). Mean heart rate increased 17.2 beats/min, and diastolic blood pressure increased 8 mmHg in the entire group in the standing compared with supine position. There were no significant differences in these changes above and below 30 yr of age. We conclude that the influence of the two major mechanisms that modulate heart rate decline at significantly different rates with aging.

scholarly journals Cross-Spectral Analysis of Electrocardiographic and Nostril Airflow Signals Identifies Two Respiratory Frequencies of Heart Rate Modulation

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Wan-An Lu ◽  
Jui-Feng Lin ◽  
Chen-Hsu Wang ◽  
Yung-Sheng Chen ◽  
Ying-Hua Shieh ◽  
...  
Keyword(s):  
Heart Rate ◽  
Spectral Analysis ◽  
High Frequency ◽  
Healthy Subjects ◽  
Low Frequency ◽  
High Frequency Power ◽  
Very Low Frequency ◽  
The Cross ◽  
Low Frequency Power ◽  
Frequency Power

Respiration is known to be a significant modulator of heart rate, and the high-frequency component in the power spectrum of heart rate variability (HRV) is believed to be caused mainly by respiration. To investigate the effect of respiration on heart rate, cross-spectral analysis of electrocardiographic (ECG) and nostril airflow signals was performed in healthy subjects to find the common features of ECG and respiration. Forty-two healthy subjects were included in this study. The autospectra of respective ECG and nostril airflow signals and the cross-spectra of ECG and nostril airflow signals were obtained and compared with the corresponding conventional HRV measures. We found that there were two spectral peaks at around 0.03 Hz and 0.3 Hz in the autospectrum of nostril airflow and the cross-spectrum of ECG and nostril airflow. In addition, the cross-spectral normalized high-frequency power (nHFPcs) was significantly larger than that of conventional HRV, while the cross-spectral normalized very low-frequency power (nVLFPcs), normalized low-frequency power (nLFPcs), and low-/high-frequency power ratio (LHRcs) were significantly lower than those of the conventional HRV. The cross-spectral nLFPcs and LHRcs had positive correlations with their corresponding HRV measures. We conclude that cross-spectral analysis of ECG and nostril airflow signals identifies two respiratory frequencies at around 0.03 Hz and below and around 0.3 Hz and can yield significantly enhanced nHFPcs and significantly suppressed nVLFPcs, as compared to their counterparts in conventional HRV. Both very low-frequency and high-frequency components of HRV are caused in part or mainly by respiration.

Elevated heart rate variability in physically active postmenopausal women: a cardioprotective effect?

1996 ◽  
Vol 271 (2) ◽  
pp. H455-H460 ◽  
Author(s):  
K. P. Davy ◽  
N. L. Miniclier ◽  
J. A. Taylor ◽  
E. T. Stevenson ◽  
D. R. Seals
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Postmenopausal Women ◽  
High Frequency ◽  
Low Frequency ◽  
Total Power ◽  
High Frequency Power ◽  
Fat Percentage ◽  
Physically Active ◽  
Frequency Power

Coronary heart disease (CHD) and cardiac sudden death (CSD) incidence accelerates after menopause, but the incidence is lower in physically active versus less active women. Low heart rate variability (HRV) is a risk factor for CHD and CSD. The purpose of the present investigation was to test the hypothesis that HRV at rest is greater in physically active compared with less active postmenopausal women. If true, we further hypothesized that the greater HRV in the physically active women would be closely associated with an elevated spontaneous cardiac baroreflex sensitivity (SBRS). HRV (both time and frequency domain measures) and SBRS (sequence method) were measured during 5-min periods of controlled frequency breathing (15 breaths/min) in the supine, sitting, and standing postures in 9 physically active postmenopausal women (age = 53 +/- 1 yr) and 11 age-matched controls (age = 56 +/- 2 yr). Body weight, body mass index, and body fat percentage were lower (P < 0.01) and maximal oxygen uptake was higher (P < 0.01) in the physically active group. The standard deviation of the R-R intervals (time domain measure) was higher in all postures in the active women (P < 0.05) as were the high-frequency, low-frequency, and total power of HRV. SBRS also was higher (P < 0.05) in the physically active women in all postures and accounted for approximately 70% of the variance in the high-frequency power of HRV (P < 0.05). The results of the present investigation indicate that physically active postmenopausal women demonstrate higher levels of HRV compared with age-matched, less active women. Furthermore, SBRS accounted for the majority of the variance in the high-frequency power of HRV, suggesting the possibility of a mechanistic link with cardiac vagal modulation of heart rate. Our findings may provide insight into a possible cardioprotective mechanism in physically active postmenopausal women.

Effects of oral arsenic trioxide therapy on QT intervals in patients with acute promyelocytic leukemia: implications for long-term cardiac safety

Blood ◽  
2006 ◽  
Vol 108 (1) ◽  
pp. 103-106 ◽  
Author(s):  
Chung-Wah Siu ◽  
Wing-Yan Au ◽  
Cindy Yung ◽  
Cyrus R. Kumana ◽  
Chu-Pak Lau ◽  
...  
Keyword(s):  
Arsenic Trioxide ◽  
High Frequency ◽  
Peak Plasma ◽  
Low Frequency ◽  
Holter Monitoring ◽  
Cardiac Safety ◽  
High Frequency Power ◽  
Qt Intervals ◽  
Frequency Power

Ventricular tachyarrhythmias may occur during intravenous arsenic trioxide (As2O3). This has not happened during oral As2O3. Sixteen patients were studied by electrocardiography and 24-hour Holter monitoring at baseline, during and after oral As2O3 (As2O3-ON, As2O3-OFF). QT and corrected QT (QTc) were significantly longer during As2O3-ON than in As2O3-OFF, but QT and QTc dispersions were comparable. The patients' 24-hour heart rates were higher during As2O3-ON than in As2O3-OFF. QTc intervals at each hour were longer during As2O3-ON than in As2O3-OFF. However, QTc prolongation of more than 30 milliseconds only occurred at one time point (2 hours) after oral As2O3, resulting in QTc of more than 500 milliseconds in 3 of 16 patients, all within 4 hours of oral As2O3. Although the standard deviation of normal RR interval was lower during As2O3-ON, ratios of low frequency to high frequency power for As2O3-ON and As2O3-OFF were comparable. No ventricular proarrhythmias were observed. These observations, due to the lower peak plasma arsenic reached during oral As2O3, may explain the relative cardiac safety of oral As2O3. (Blood. 2006;108:103-106)

Topographic Electroencephalographic Study with Power Ratio Index Mapping in Patients with Malignant Brain Tumors

Neurosurgery ◽  
1985 ◽  
Vol 17 (4) ◽  
pp. 613-619 ◽  
Author(s):  
Ken Nagata ◽  
Cordell E. Gross ◽  
Glenn W. Kindt ◽  
J. Michael Geier ◽  
Geoffrey R. Adey
Keyword(s):  
Brain Tumors ◽  
High Frequency ◽  
Low Frequency ◽  
Power Ratio ◽  
Malignant Brain Tumors ◽  
Power Spectral ◽  
Beta Power ◽  
Index Mapping ◽  
Low Frequency Power ◽  
Frequency Power

Abstract A variant of electroencephalogram (EEG) power spectral mapping called power ratio index (PRI) mapping was used to monitor 15 patients with malignant brain tumors. This index is generated by dividing the low frequency (delta, theta) power by the high frequency (alpha, beta) power. Because the nonparoxysmal effect of a brain tumor on the EEG is reflected as a relative loss of high frequency power and a gain in low frequency power, utilization of the PRI has the effect of placing the epicenter of the “power dysfunction” coincident with the epicenter of the tumor.

Design and Numerical Analysis of an Electrostatic Energy Harvester With Impact for Frequency Up-Conversion

2020 ◽  
Vol 15 (5) ◽  
Author(s):  
R. Lensvelt ◽  
R. H. B. Fey ◽  
R. M. C. Mestrom ◽  
H. Nijmeijer
Keyword(s):  
Power Generation ◽  
High Frequency ◽  
Energy Harvester ◽  
Low Frequency ◽  
Electrostatic Energy ◽  
Computational Time ◽  
Ambient Vibrations ◽  
Frequency Oscillator ◽  
Low Frequency Power ◽  
Frequency Power

Abstract Integration of vibration energy harvesters (VEHs) with small-scale electronic devices may form an attractive alternative for relatively large batteries and can, potentially, increase their lifespan. However, the inherent mismatch between a harvester's high-frequency resonance, typically in the range 100−1000 Hz, relative to the available low-frequency ambient vibrations, typically in the range 10–100 Hz, means that low-frequency power generation in microscale VEHs remains a persistent challenge. In this work, we model a novel electret-based, electrostatic energy harvester (EEH) design. In this design, we combine an out-of-plane gap-closing comb (OPGC) configuration for the low-frequency oscillator with an in-plane overlap comb configuration for the high-frequency oscillator and employ impact for frequency up-conversion. An important design feature is the tunability of the resonance frequency through the electrostatic nonlinearity of the low-frequency oscillator. Impulsive normal forces due to impact are included in numerical simulation of the EEH through Moreau's time-stepping scheme which has, to the best of our knowledge, not been used before in VEH design and analysis. The original scheme is extended with time-step adjustments around impact events to reduce computational time. Using frequency sweeps, we numerically investigate power generation under harmonic, ambient vibrations. Results show improved low-frequency power generation in this EEH compared to a reference EEH. The EEH design shows peak power generation improvement of up to a relative factor 3.2 at low frequencies due to the occurrence of superharmonic resonances.

scholarly journals Heart Rate Variability during Face Cooling in Concussed Adolescents

Neurology ◽  
2019 ◽  
Vol 93 (14 Supplement 1) ◽  
pp. S8.1-S8
Author(s):  
Mohammad Haider ◽  
Charles Wilber ◽  
Kaitlin Viera ◽  
Itai Bezherano ◽  
John Leddy
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
High Frequency Power ◽  
Clinical Recovery ◽  
Face Cooling ◽  
Ratio Measure ◽  
Frequency Power ◽  
Mean Heart Rate

ObjectiveWe measured heart rate variability (HRV) during physiological stimuli in acutely concussed adolescents (CX) and after clinical recovery, and compared with healthy controls (HC).BackgroundConcussion is associated with autonomic dysfunction. Face Cooling (FC) triggers the trigeminal nerve to evoke transient increases in cardiac parasympathetic (PNS) activity.Design/Methods11 CX (14.8 ± 0.9 years, 6 male, 7 days since injury) and 11 HC (16.1 ± 1.1 years, 9 male) participated. We calculated mean heart rate (HR), standard deviation of root mean square (RMSSD, measure of PNS tone) and low-frequency to high-frequency power ratio (LF/HF ratio, measure of sympathetic [SNS] tone) at rest and 3-minute FC test.ResultsCX at Visit 1 and 2 had significantly lesser increase in HR (p = 0.02) and RMSSD (p = 0.038) than HC on FC.ConclusionsThese data show that acutely concussed participants have an attenuated PNS response to physiological stimuli which continues after clinical recovery.

Resting Autonomic Function in Active and Insufficiently Active People Living with HIV

2017 ◽  
Vol 39 (01) ◽  
pp. 73-78 ◽  
Author(s):  
Norberto Quiles ◽  
Carol Garber ◽  
Joseph Ciccolo
Keyword(s):  
High Frequency ◽  
Autonomic Function ◽  
Low Frequency ◽  
People Living With Hiv ◽  
Autonomic Responses ◽  
Resting Heart Rate Variability ◽  
Low Frequency Power ◽  
Normalized Units ◽  
Living With Hiv ◽  
Frequency Power

AbstractAutonomic dysfunction appears to be prevalent in people living with HIV/AIDS (PLWHA). However, there are limited data on the resting autonomic responses to exercise in active and insufficiently active PLWHA. We aimed to determine whether active PLWHA have better autonomic responses compared with insufficiently active PLWHA. Active PLWHA receiving anti-retroviral therapy (n=13) and insufficiently active PLWHA (n=10) were recruited. A 10-min recording of the supine electrocardiogram was taken. Resting heart rate variability was analyzed from this electrocardiogram. Parasympathetic modulation, as measured by high frequency power in normalized units, was greater in active PLWHA when compared to insufficiently active PLWHA (41.0±15.6 vs. 25.2±9.7; p<0.05). Sympathetic modulation as measured by low frequency power in normalized units was greater in insufficiently active PLWHA when compared to active PLWHA (55.6±15.8 vs 79.3±17.5; p<0.05). Sympathovagal balance as measured by low frequency/high frequency ratio was greater in insufficiently active PLWHA when compared to active PLWHA (3.4±1.8 vs 1.6±0.9; p<0.05), indicating greater parasympathetic dominance in the active group. In conclusion, PLWHA who regularly exercised demonstrated enhanced autonomic function compared with insufficiently active PLWHA. These results suggest that exercise is associated with enhanced autonomic function, and may improve cardiovascular risk.

scholarly journals Estrogen Can Modulate Menopausal Women’s Heart Rate Variability

2013 ◽  
pp. S165-S171 ◽  
Author(s):  
S.-G. YANG ◽  
M. MLČEK ◽  
O. KITTNAR
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Postmenopausal Women ◽  
Low Frequency ◽  
Premenopausal Women ◽  
High Frequency Power ◽  
Substitution Therapy ◽  
Low Frequency Power ◽  
Frequency Power

The aim of our study was to compare the responses of heart rate variability (HRV) with two different types of hormonal substitution therapy (HT) in post-menopausal women (cross-sectional study) and to reveal an effect of HT shortly after beginning of its administration (follow-up study). To elucidate the influence of menopause and effects of different protocols of a HT on autonomic control of heart rate, we evaluated the heart rate variability (HRV) in 5 groups: premenopausal women (n=140), postmenopausal women without HT (n=360), women on HT with conjugated estrogen only (n=168), women on continuous combined estrogen-progesterone HT (n=117), and men (n=140). Frequency-domain of short-term stationary R-R intervals was performed to evaluate the total variance, low frequency power (LF; 0.04-0.15 Hz), high frequency power (HF; 0.15-0.40 Hz), portion of low frequency power (LF%) and ratio of LF to HF (LF/HF). Significantly lower portion of the LF was found in premenopausal women [46.9 (±2.7) nu] when compared to untreated postmenopausal women [54.3 (±2.9) nu] and men [55.2 (±3.0) nu]. Treatment by estrogen only was proved to decrease the LF% [40.1 (±2.1) nu] while no effect on HRV was observed in women treated with combination of estrogen and progesterone [57.2 (±3.1) nu]. Also the HF was lower in postmenopausal women [4.16 (±0.16) ms2] than in premenopausal women [4.79 (±0.22) ms2] and women treated with estrogen only [4.98 (±0.25) ms2] while in women treated with combined hormonal therapy the average value [3.99 (±0.21) ms2] did not significantly differ from that of untreated postmenopausal women. The follow-up study also proved increase of high frequency power already after two months of estrogen substitution therapy [4.86 (±0.14) ms2 vs. 4.19 (±0.15) ms2]. These results suggest that higher vagal modulation of heart rate that seems typical for younger women becomes after menopause similar to that of men. We also proved a positive shift of HRV parameters toward more beneficial values as for a cardiovascular risk in postmenopausal women treated with estrogens but not in those treated by combined estrogen – progesterone substitution therapy.

Sign in / Sign up

Export Citation Format

Share Document