Percent duration of heart rate acceleration within the respiratory cycle: a novel approach to assess heart rate asymmetry.

Accelerations and decelerations of heart rate are nonsymmetrical in the magnitude and number of beat-to-beat changes. The asymmetric features of heart rate variability are related to respiratory durations. To explore the link between respiration and heart rate asymmetry (HRA), we evaluated 14 seated, healthy young adults who breathed with nine combinations of inspiration duration (TI) and expiration duration (TE), chosen respectively from 2, 4, and 6 s. A 5-min R-R interval (RRI) time series was obtained from each study period to construct an averaged pattern waveform relative to the respiratory cycle. We observed that the time interval between inspiration onset and RRI minimum progressively lengthened as TI and TE increased. The time interval between expiration onset and RRI maximum also lengthened when TE increased but shortened when TI increased. Consequently, TI and TE had different effects on the acceleration time (AT; from RRI maximum to RRI minimum) and deceleration time (DT; from RRI minimum to RRI maximum). The percentage of AT within the respiratory cycle showed a strong correlation with traditional Guzik's (r = 0.862, P < 0.001) and Porta's (r = 0.878, P < 0.001) indexes of HRA assessed in a Poincaré plot analysis. These findings suggest that, in addition to considering the magnitude and number of beat-to-beat changes, HRA can also be assessed based on another aspect: the duration of consecutive changes. The stepwise link between the duration of heart rate change and respiratory duration provides insight into the mechanisms connecting respiration to HRA.NEW & NOTEWORTHY In healthy adults who regulated their breathing across nine combinations of inspiration and expiration durations, we used averaged pattern waveform technique to quantify the durations of heart rate acceleration and deceleration within the respiratory cycle. The percent duration of acceleration showed a strong correlation with traditional heart rate asymmetry indexes, which evaluate the magnitude and number of beat-to-beat changes. This new approach opens a window to explore the asymmetric features of heart rate variability.

Nociception Effect on Frontal Electroencephalogram Waveform and Phase-Amplitude Coupling in Laparoscopic Surgery.

BACKGROUND: Electroencephalographic pattern changes during anesthesia reflect the nociception-analgesia balance. Alpha dropout, delta arousal, and beta arousal with noxious stimulation have been described during anesthesia; however, data on the reaction of other electroencephalogram signatures toward nociception are scarce. Analyzing the effects of nociception on different electroencephalogram signatures may help us find new nociception markers in anesthesia and understand the neurophysiology of pain in the brain. This study aimed to analyze the electroencephalographic frequency pattern and phase-amplitude coupling change during laparoscopic surgeries. METHODS: This study evaluated 34 patients who underwent laparoscopic surgery. The electroencephalogram frequency band power and phase-amplitude coupling of different frequencies were analyzed across 3 stages of laparoscopy: incision, insufflation, and opioid stages. Repeated-measures analysis of variance with a mixed model and the Bonferroni method for multiple comparisons were used to analyze the changes in the electroencephalogram signatures between the preincision and postincision/postinsufflation/postopioid phases. RESULTS: During noxious stimulation, the frequency spectrum showed obvious decreases in the alpha power percentage after the incision (mean ± standard error of the mean [SEM], 26.27 ± 0.44 and 24.37 ± 0.66; P < .001) and insufflation stages (26.27 ± 0.44 and 24.40 ± 0.68; P = .002), which recovered after opioid administration. Further phase-amplitude analyses showed that the modulation index (MI) of the delta-alpha coupling decreased after the incision stage (1.83 ± 0.22 and 0.98 ± 0.14 [MI × 10 3 ]; P < .001), continued to be suppressed during the insufflation stage (1.83 ± 0.22 and 1.17 ± 0.15 [MI × 10 3 ]; P = .044), and recovered after opioid administration. CONCLUSIONS: Alpha dropout during noxious stimulation is observed in laparoscopic surgeries under sevoflurane. In addition, the modulation index of delta-alpha coupling decreases during noxious stimulation and recovers after the administration of rescue opioids. Phase-amplitude coupling of the electroencephalogram may be a new approach for evaluating the nociception-analgesia balance during anesthesia.

Different effects of inspiratory duration and expiratory duration on heart rate deceleration capacity and heart rate asymmetry.

PURPOSE: Low values of heart rate deceleration capacity (DC) and heart rate asymmetry (HRA) are associated with cardiovascular risks. Slow respiration has been proven to enhance the magnitudes of these indexes, but individual inspiratory (TI) and expiratory (TE) durations were not controlled in most studies. This study aims to examine whether the effects of TI and TE on these indexes would be the same and, if not, how to adjust TI and TE to maximize the effect of slow respiration. METHODS: We evaluated 14 seated healthy young adults who randomly controlled their breathing to nine combinations of TI and TE, each chosen respectively from 2, 4, and 6 s. A 5-min R-R interval time series was obtained from each study period for further analysis. RESULTS: The magnitude of DC increased when TI or TE increased, while that of acceleration capacity (AC) remained almost unchanged by TI. We further defined a new index as 100 × DC2/(DC2 + AC2) and found it to be correlated with conventional Guzik's (r = 0.94) and Porta's (r = 0.99) indexes of HRA during different combinations of TI and TE. Increasing TI and increasing TE both enhanced the magnitudes of HRA indexes, with TI taking effect when ≤ 4 s, and TE taking effect when > 4 s. DC and HRA indexes were maximized with a TI of 4 s and a TE of 6 s. CONCLUSION: We suggest that a TI of 3-4 s with a TE of 7-6 s is an appropriate standard for slow respiration.

Mouth puffing phenomena of patients with obstructive sleep apnea when mouth-taped: device's efficacy confirmed with physical video observation.

PURPOSE: This study aimed to design a device to monitor mouth puffing phenomena of patients with obstructive sleep apnea when mouth-taped and to employ video recording and computing algorithms to double-check and verify the efficacy of the device. METHODS: A mouth puffing detector (MPD) was developed, and a video camera was set to record the patients' mouth puffing phenomena in order to make ensure the data obtained from the device was appropriate and valid. Ten patients were recruited and had polysomnography. A program written in Python was used to investigate the efficacy of the program's algorithms and the relationship between variables in polysomnography (sleep stage, apnea-hypopnea index or AHI, oxygen-related variables) and mouth puffing signals (MPSs). The video recording was used to validate the program. Bland-Altman plot, correlations, independent sample t-test, and ANOVA were analyzed by SPSS 24.0. RESULTS: Patients were found to mouth puff when they sleep with their mouths taped. An MPD was able to detect the signals of mouth puffing. Mouth puffing signals were noted and categorized into four types of MPSs by our algorithms. MPSs were found to be significantly related to relative OSA indices. When all participants' data were divided into minutes, intermittent mouth puffing (IMP) was found to be significantly different from non-mouth puffing in AHI, oxygen desaturation index (ODI), and time of oxygen saturation under 90% (T90) (AHI: 0.75 vs. 0.31; ODI: 0.75 vs. 0.30; T90: 5.52 vs. 1.25; p < 0.001). Participants with severe OSA showed a higher IMP percentage compared to participants with mild to moderate OSA and the control group (severe: 38%, mild-to-moderate: 65%, control: 95%; p < 0.001). CONCLUSIONS: This study established a simple way to detect mouth puffing phenomena when patients were mouth-taped during sleep, and the signals were classified into four types of MPSs. We propose that MPSs obtained from patients wearing the MPD can be used as a complement for clinicians to evaluate OSA.

Comparison of the effect of 360° versus two-dimensional virtual reality video on history taking and physical examination skills learning among undergraduate medical students: a randomized controlled trial.

Before caring for patients, video instruction is commonly used for undergraduate medical students, and 360° virtual reality (VR) videos have gained increasing interest in clinical medical education. Therefore, the effect of immersive 360° VR video learning compared with two-dimensional (2D) VR video learning in clinical skills acquisition should be evaluated. This randomized, intervention-controlled clinical trial was aimed to assess whether immersive 360° VR video improves undergraduate medical students' learning effectiveness and reduces the cognitive load in history taking and physical examination (H&P) training. From May 1 2018 to October 30 2018, 64 senior undergraduate medical students in a tertiary academic hospital were randomized to receive a 10-min immersive 360° (360° VR video group; n = 32) or 2D VR instructional video (2D VR video group; n = 32), including essential knowledge and competency of H&P. The demographic characteristics of the two groups were comparable for age, sex, and cognitive style. The total procedure skill score, physical examination score, learner's satisfaction score, and total cognitive load in the 360° VR video group were significantly higher than those in the 2D VR video group (effect sizes [95% confidence interval]: 0.72 [0.21-1.22], 0.63 [0.12-1.13], 0.56 [0.06-1.06], and 0.53 [0.03-1.03], respectively). This study suggested that a10-minute 360° VR video instruction helped undergraduate medical students perform fundamental H&P skills as effectively as 2D VR video. Furthermore, the 360° VR video might result in significantly better procedural metrics of physical examinations with higher learner satisfaction despite the higher cognitive load. Supplementary Information: The online version contains supplementary material available at 10.1007/s10055-022-00664-0.

Associations of Reduced Sympathetic Neural Activity and Elevated Baroreflex Sensitivity With Non-Rapid Eye Movement Sleep: Evidence From Electroencephalogram- and Electrocardiogram-Based Sleep Staging.

OBJECTIVE: Autonomic neural controls in sleep regulation have been previously demonstrated; however, whether these alternations can be observed by different sleep staging approaches remains unclear. Two established methods for sleep staging-the standardized visual scoring and the cardiopulmonary coupling (CPC) analysis based on electrocardiogram-were used to explore the cardiovascular profiles of sleep. METHODS: Overnight polysomnography was recorded together with continuous beat-to-beat blood pressure. Cortical activity, heart rate variability, blood pressure variability, and baroreflex sensitivity during sleep stages from 24 nights of sleep were obtained from 15 normotensive participants and analyzed. RESULTS: Non-rapid eye movement sleep (NREM) from visual scoring and restful sleep (RS) of CPC both showed the highest delta power of electroencephalogram (EEG) and lowest beta activity of EEG in comparison with other sleep stages (p < .001); likewise, the lowest total power of heart rate variability and suppressed vascular-sympathetic activity, reflected by low-frequency power of blood pressure variability, as well as a trend in elevated baroreflex sensitivity, were observed in the NREM or RS. This suppressed vascular-sympathetic activity during stable sleep further exhibited a significant correlation with increased slow-wave activity (NREM: r = -0.292 ± 0.34, p = .002; RS: r = -0.209 ± 0.30, p = .010). CONCLUSIONS: Autonomic nervous system is evidently associated with stable sleep, as indicated by the similar findings obtained from sleep stages categorized by standardized visual scoring or CPC analysis. Such association between cardiovascular neural activity and sleep EEGs can be observed regardless of the sleep staging approach followed.

Age and sex differences on the association between anxiety disorders and obstructive sleep apnea: A nationwide case-control study in Taiwan.

AIM: The aim of this study was to examine the association between anxiety disorders and obstructive sleep apnea (OSA). METHODS: This is a population-based, retrospective case-control study using Taiwan's nationwide database. We included patients with OSA aged ≥12 years, diagnosed according to the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes: 327 and 780. Each enrolled patient with OSA needed to undergo a polysomnography examination within 1 year pre- or post-OSA occurrence. Patients with OSA and controls were selected in a 1:4 ratio. Patients with anxiety disorders (ICD-9-CM code 300) were diagnosed by board-certified psychiatrists and required to visit the outpatient clinic at least three times per year. Multivariate logistic regression and interaction analyses were used to evaluate the objective association. RESULTS: This study enrolled 7987 and 31 948 participants with and without OSA, respectively. A significant difference in anxiety exposure was observed only pre-OSA diagnosis but not post-OSA diagnosis. Compared with patients without anxiety disorders: (i) those with anxiety disorders had an adjusted odds ratio (aOR) of ≈1.864 in OSA comorbidity (aOR = 1.864; 95% confidence interval [CI] = 1.337-2.405); and (ii) subgroup analysis showed a significant interaction that anxiety patients of male sex, aged 18 to 44 years, aged 45 to 64 years, and hypertension had a higher aOR in OSA comorbidity (aOR = 2.104 [95% CI = 1.436-2.589], aOR = 1.942 [95% CI = 1.390-2.503], aOR = 2.179 [95% CI = 1.564-2.811], and aOR = 2.092 [95% CI = 1.497-2.706], respectively). CONCLUSION: The study revealed a higher ratio of previous anxiety exposure in patients with OSA. Compared with those without anxiety, anxiety patients of male sex, aged 18 to 64 years, and with hypertension had a higher risk of OSA comorbidity.

Mild simulator sickness can alter heart rate variability, mental workload, and learning outcomes in a 360° virtual reality application for medical education: a post hoc analysis of a randomized controlled trial.

Virtual reality (VR) applications could be beneficial for education, training, and treatment. However, VR may induce symptoms of simulator sickness (SS) such as difficulty focusing, difficulty concentrating, or dizziness that could impair autonomic nervous system function, affect mental workload, and worsen interventional outcomes. In the original randomized controlled trial, which explored the effectiveness of using a 360° VR video versus a two-dimensional VR video to learn history taking and physical examination skills, only the former group participants had SS. Therefore, 28 undergraduate medical students who participated in a 360° VR learning module were included in this post hoc study using a repeated measures design. Data of the Simulator Sickness Questionnaire (SSQ), heart rate variability (HRV) analysis, Task Load Index, and Mini-Clinical Evaluation Exercise were retrospectively reviewed and statistically analyzed. Ten (36%) participants had mild SS (total score > 0 and ≤ 20), and 18 (64%) had no SS symptom. Total SSQ score was positively related to the very low frequency (VLF) band power, physical demand subscale, and frustration subscale, and inversely related to physical examination score. Using multilevel modeling, the VLF power mediated the relationship between total SSQ score and physical examination score. Furthermore, frustration subscale moderated the mediating effects of the VLF power. Our results highlight the importance of documenting SS to evaluate a 360° VR training program. Furthermore, the combination of HRV analysis with mental workload measurement and outcome assessments provided the important clinical value in evaluating the effects of SS in VR applications in medical education.

Heart Rate Variability Reactivity to Food Image Stimuli is Associated with Body Mass Index.

Appetitive control is driven by the hedonic response to food and affected by several factors. Heart rate variability (HRV) signals have been used to index autonomic activity and arousal levels towards visual stimuli. The current research aimed to examine the influence of body mass index (BMI), disordered eating behaviors, and sex on the HRV reactivity to food in a nonclinical sample. Thirty-eight healthy male and sixty-one healthy female participants completed questionnaires assessing disordered eating symptoms. HRV was recorded when the participants received visual stimuli of high-calorie food, neutral and negative emotional signals. Generalized estimating equation models were used to investigate the associations between HRV, BMI, disordered eating behaviors, and sex across the three stimulus types. Male participants demonstrated a higher ratio of low-frequency power to high-frequency power (LF/HF) than females across all the stimulus types. An increase in LF/HF reactivity to food signals was observed in all the study subjects. The moderation effect of BMI on LF/HF in response to food signals was also observed. Our study suggests that body weight may play a role in the interaction between sympathetic activity and food stimuli; however, how the interaction between sympathetic activity and food stimuli contributes to diet control warrants further investigation.

The Impact of Estrogen Supplementation to Autonomic and Sleep Modulations in Free-Moving Spontaneously Hypertensive Rats.

Sleep and estrogen levels have an impact on neural regulation and are associated with cardiovascular (CV) events. We investigated the effects of estrogen on heart rate variability (HRV) and circadian cycle in spontaneously hypertensive rats (SHRs). Polysomnographic recording was performed in seven male and seven female SHRs during sleep. The electroencephalogram (EEG) and electromyogram (EMG) were evaluated to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS) stages. Cardiac activities were measured by RR interval of the electrocardiogram (ECG), mean arterial pressure (MAP), and power spectrum of HRV.In ECG, estrogen prolonged the RR interval in total sleep when compared with that at baseline in male SHRs (203.74 ± 6.61 versus 181.30 ± 8.06 ms, P < 0.001) and in female SHRs (169.21 ± 6.43 versus 160.76 ± 10.66 ms, P < 0.05). In HRV, the estrogen increased the high frequency (HF) in total sleep when compared with that at baseline in male SHRs (1.03 ± 0.28 versus 0.60 ± 0.43 ln (ms2), P < 0.001) and in female SHRs (0.71 ± 0.26 versus 0.42 ± 0.19 ln (ms2), P < 0.05).In male SHRs, estrogen increased the frequency of QS (26.50 ± 4.85 versus 20.79 ± 5.07, P < 0.01) and PS (25.64 ± 5.18 versus 20.14 ± 4.75, P < 0.05) stages when compared with baseline. In female SHRs, estrogen increased the percentage of delta waves in total sleep (79.87% ± 3.10% versus 76.71% ± 2.74%, P < 0.05) when compared with that at baseline.In HRV, estrogen leads to neuromodulation by increased parasympathetic tone in all SHRs, suggesting a lower risk to CV events. In sleep analyses, estrogen in male SHRs caused poor sleep quality. In contrast, estrogen in female SHRs demonstrated improved quality of sleep and decreased risk of hypertension.

Heart rate variability as a predictor of rapid renal function deterioration in chronic kidney disease patients.

AIM: Autonomic dysfunction contributes to cardiovascular morbidity/mortality and can be evaluated with heart rate variability (HRV). This study is to evaluate the prognostic significance of HRV on renal function in non-dialysis chronic kidney disease (CKD) patients. METHODS: We enrolled 326 non-dialysis CKD patients in this prospective observational study. The median follow-up period was 2.02 years. Five-minutes of electrocardiography recordings obtained at enrolment were reprocessed to assess HRV. Five frequency-domain measures and one time-domain measures were obtained. Rapid CKD progression was defined as annual estimated glomerular filtration rate (eGFR) loss over 30% per year or eGFR decline rate over 3 mL/min per 1.73 m2 per year. The prevalence of abnormal HRV, associated factors of HRV and impact of HRV on the risk of CKD progression were analyzed. RESULTS: The abnormality of HRV increased along with the severity of CKD. In patients with stage 5 CKD, the proportion of abnormal ln(low frequency power) (LF), ln(high frequency power) (HF), lnLF/HF were 69.5, 52.8 and 50%, respectively. Associated factors of HRV included advanced CKD, diabetes mellitus, serum albumin, severe proteinuria, Beck Anxiety Inventory score, erythropoietin use, renin-angiotensin system inhibitors and heart failure. Multivariate logistic regression model analysis revealed lower lnLF/HF, hypertension and severe proteinuria were the risk factors of rapid CKD progression. CONCLUSION: The prevalence of autonomic dysfunction measured by HRV among each stage CKD patients is different. Most patients in advanced CKD stage have reduced values of HRV parameters. The estimation of lnLF/HF also provided prognostic information on CKD progression in addition to classical risk factors.

Changes in Sleep Architecture under Sustained Pain in Adult Male Rats Subjected to Neonatal Short-Lasting Local Inflammatory Insult.

Neonatal, short-lasting, local, nociceptive insult by carrageenan can cause long-term alterations in somatosensory and neurohumoral systems. We previously revealed hyporesponsiveness of the autonomic nervous system (ANS) after painful stimulation of adult rats in a neonatal carrageenan-induced pain model. Sleep disturbance has been highly correlated with pain and ANS activity. In the present study, adult rats that had received an intraplantar injection of carrageenan on postnatal day 1 were investigated to determine if there were alterations in their sleep architecture upon the stimulation of pain. Polysomnographic and heart rate variability recordings were carried out, with a wireless transmission of data, for 24 h under baseline conditions and after an intraplantar injection of complete Freund's adjuvant to induce sustained nociception. Increased active awake (AW) and decreased quiet sleep (QS) and paradoxical sleep (PS) times were noted in the control animals. In the carrageenan-treated rats, the AW time increased but with decreased alertness, as revealed by decreases in beta and increases in theta power. The QS time did not decrease. The PS time decreased during the first 12 h, then increased during the following 12 h, suggesting an early rebound of formerly deprived PS time. Sympathetic activation under sustained pain was not apparent in any stage of sleep in carrageenan-treated rats and was even suppressed in AW time. An impaired sympathetic reaction to pain may have contributed to the atypical changes in sleep architecture in these rats. In conclusion, pain in early life has a long-term effect on the cardiovascular-autonomic-electroencephalographic responses to pain later in life. The physiological relevance of these results remains undetermined.

Measures of Heart Rate Variability in Individuals With Somatic Symptom Disorder.

OBJECTIVE: Little is known about autonomic nervous system activity in individuals with somatic symptom disorder (SSD) as defined by DSM-V criteria. The aims of this study were to investigate whether individuals with SSD differ from healthy controls in heart rate variability (HRV) measures of autonomic nervous system activity and whether sex has a moderating effect on this association. METHODS: We recruited 168 individuals with SSD (35.1% men) and 106 healthy controls (27.4% men). Demographics, HRV, and psychological factors were measured using the Patient Health Questionnaire-15, Health Anxiety Questionnaire, Beck Depression Inventory-II (BDI-II), and Beck Anxiety Inventory. Multiple regression analysis was used to examine the association of SSD with HRV, adjusting for demographic and psychological measures. RESULTS: Individuals with SSD had lower levels of total-power HRV and low-frequency HRV, but no differences in high-frequency (HF)-HRV were found. HRV differences between SSD and controls varied by sex and age (triple interaction TP-HRV ß = -0.222, p < .001; low-frequency HRV ß = -0.332, p < .001; and HF-HRV ß = -0.167, p = .006). Whole-sample multiple regression analyses revealed significant sex differences in the magnitudes of the association between BDI-II with HF-HRV (ß of sex*BDI-II: 0.761, p = .005) and analyses stratified by sex indicated that HF-HRV was significantly correlated with depression in men with SSD (r = -0.491, p < .001) but not in women with SSD (r = 0.057, p = .558). CONCLUSIONS: These results suggest that patients with SSD demonstrate different patterns of HRV and the patterns of association between HRV indices and psychological factors vary between men and women.

The relationships between heart rate deceleration capacity and spectral indices of heart rate variability during different breathing frequencies.

PURPOSE: The frequency of breathing influences the spectral powers of heart rate variability (HRV) as well as the magnitudes of heart rate deceleration capacity (DC) and acceleration capacity (AC). We compared the strength of their relationships under different breathing frequencies. METHODS: We studied 14 healthy young adults who breathed spontaneously and controlled their breathing rates to 0.1, 0.2, 0.3 and 0.4 Hz in a supine position. A 5-min R-R interval time series without movement artefacts or ectopic beats was obtained for each study period. Spectral indices were defined as the square roots of spectral powers in the very low frequency (0.01-0.04 Hz), low frequency (0.04-0.15 Hz), high frequency (0.15-0.4 Hz) and respiratory frequency bands. We also combined these frequency bands into LHF (0.04-0.4 Hz) and VLHF (0.01-0.4 Hz). DC and AC were obtained using phase rectified signal averaging. RESULTS: DC and AC were significantly correlated with all indices of HRV. The within-subject correlation coefficients for the LHF index had the greatest absolute values (0.953 and -0.919, respectively). DC and AC had different strength of relationships with the LHF index, but became comparable (0.954 vs. -0.943) when the data obtained under 0.1-Hz breathing were excluded. CONCLUSION: DC is strongly correlated with the spectral index of the LHF band, indicating that they are controlled by similar influences under the conditions used in this study. AC is less related to the LHF index due to the fact that its magnitude deceases during 0.1-Hz breathing.

Novel application of multi dynamic trend analysis as a sensitive tool for detecting the effects of aging and congestive heart failure on heart rate variability.

The complex fluctuations in heart rate variability (HRV) reflect cardiac autonomic modulation and are an indicator of congestive heart failure (CHF). This paper proposes a novel nonlinear approach to HRV investigation, the multi dynamic trend analysis (MDTA) method, based on the empirical mode decomposition algorithm of the Hilbert-Huang transform combined with a variable-sized sliding-window method. Electrocardiographic signal data obtained from the PhysioNet database were used. These data were from subjects with CHF (mean age = 59.4 ± 8.4), an age-matched elderly healthy control group (59.3 ± 10.6), and a healthy young group (30.3 ± 4.8); the HRVs of these subjects were processed using the MDTA method, time domain analysis, and frequency domain analysis. Among all HRV parameters, the MDTA absolute value slope (MDTS) and MDTA deviation (MDTD) exhibited the greatest area under the curve (AUC) of the receiver operating characteristics in distinguishing between the CHF group and the healthy controls (AUC = 1.000) and between the healthy elderly subject group and the young subject group (AUC = 0.834 ± 0.067 for MDTS; 0.837 ± 0.066 for MDTD). The CHF subjects presented with lower MDTA indices than those of the healthy elderly subject group. Furthermore, the healthy elderly subjects exhibited lower MDTA indices than those of the young controls. The MDTA method can adaptively and automatically identify the intrinsic fluctuation on variable temporal and spatial scales when investigating complex fluctuations in the cardiac autonomic regulation effects of aging and CHF.

Effects of breathing frequency on the heart rate deceleration capacity and heart rate acceleration capacity.

PURPOSE: The deceleration capacity (DC) and acceleration capacity (AC) of heart rate as well as the respiratory rate predict outcome after acute myocardial infarction. We evaluated the relation between breathing frequency and both DC and AC, as well as the difference between them. METHODS: We studied fourteen healthy young adults who breathed spontaneously and controlled their breathing to rates of 0.1, 0.2, 0.3, and 0.4 Hz in a supine position. A 5-min R-R interval time series without movement artifacts or ectopic beats was obtained from each studied period and scanned to identify the anchor points that were characterized by a value longer or shorter than the preceding value. Averaged changes of R-R intervals surrounding the deceleration and acceleration anchors were calculated as DC and AC, respectively. RESULTS: The magnitudes of DC and AC increased progressively as breathing frequency decreased (Both p < 0.001 by one-way repeated-measures analysis of variance). The magnitude of DC was larger than the magnitude of AC during 0.1-Hz breathing (95 % confidence interval of their difference: 1.7-9.7 ms), while the difference between them reduced to near zero at higher frequencies. CONCLUSIONS: Slow breathing enhances the magnitudes of DC and AC simultaneously under the conditions used in this study. The increase in the magnitude of DC is significantly greater than that of AC.

Voluntary and involuntary running in the rat show different patterns of theta rhythm, physical activity, and heart rate.

Involuntarily exercising rats undergo more physical and mental stress than voluntarily exercising rats; however, these findings still lack electrophysiological evidence. Many studies have reported that theta rhythm appears when there is mental stress and that it is affected by emotional status. Thus we hypothesized that the differences between voluntary and involuntary movement should also exist in the hippocampal theta rhythm. Using the wheel and treadmill exercise models as voluntary and involuntary exercise models, respectively, this study wirelessly recorded the hippocampal electroencephalogram, electrocardiogram, and three-dimensional accelerations of young male rats. Treadmill and wheel exercise produced different theta patterns in the rats before and during running. Even though the waking baselines for the two exercise types were recorded in different environments, there did not exist any significant difference after distinguishing the rats' sleep/wake status. When the same movement-related parameters are considered, the treadmill running group showed more changes in their theta frequency (4-12 Hz), in their theta power between 9.5-12 Hz, and in their heart rate than the wheel running group. A positive correlation between the changes in high-frequency (9.5-12 Hz) theta power and heart rate was identified. Our results reveal various voluntary and involuntary changes in hippocampal theta rhythm as well as divergences in heart rate and high-frequency theta activity that may represent the effects of an additional emotional state or the sensory interaction during involuntary running by rats.

Effects of mind-body exercise on body constitution and circadian rhythm in people with suboptimal health status.

BACKGROUND: Suboptimal health status (SHS) is a dynamic state in which people have not been diagnosed with a disease but tend to develop diseases. People with SHS are more prone to conditions such as cardiovascular disease and metabolic syndrome. Suitable interventions in people with SHS can prevent disease development. SHS is correlated with traditional Chinese medicine (TCM)-based constitutions, including Yang-Xu (yang deficiency), Yin-Xu (yin deficiency), and stasis types. The circadian rhythm is a potential biomarker of health and metabolism. Baduanjin exercise, a kind of mind-body exercise, has been regarded to adjust body constitution and metabolism, but few studies have evaluated the effects of Baduanjin exercise on body constitution and circadian rhythms. Therefore, this randomized controlled trial investigated the effects of Baduanjin exercise on body constitution and circadian rhythms in people with SHS. METHODS: Seventy-six participants with SHS were divided into the Baduanjin exercise and control groups (watching a Baduanjin video), with the interventions lasting 12 weeks. The Body Constitution Questionnaire (BCQ), SHS Questionnaire-25 (SHSQ-25), and actigraphy for circadian rhythm measurement were conducted. RESULTS: The scores of SHSQ-25, Yang-Xu, Yin-Xu, and BCQ stasis decreased significantly after 12 weeks in the Baduanjin exercise group, but not in the control group. Interdaily stability of the circadian rhythm increased significantly in the Baduanjin exercise group but not in the control group. CONCLUSION: This is the first report of improved health status, modulated body constitution, and increased interdaily stability of the circadian rhythm in participants with SHS who practiced Baduanjin exercise.

Levilactobacillus brevis SG031 modulates mood-related behaviors and attenuates stress-related sleep disturbance and autonomic dysfunction via gut microbiota modulation in Wistar-Kyoto rats.

AIMS: The probiotic bacterium Levilactobacillus brevis (L. brevis) has been proposed as a potential solution to manage mood disorders and alleviate stress-related sleep disturbances. However, the underlying mechanisms of its effects have not been fully elucidated. The aim of this study was to explore the impact and potential mechanisms of L. brevis SG031 supplementation on anxiety/depression-like behaviors and stress-induced changes in sleep patterns and sleep-related autonomic function. MAIN METHODS: Male Wistar-Kyoto rats were administered low, medium, or high doses of L. brevis SG031 or a vehicle for 4 weeks, followed by behavioral tests to evaluate anxiety and depression. After an additional 2 weeks of SG031 or vehicle administration, a cage-exchange paradigm was performed with 24-hour physiological signal measurements under different stress conditions. Fecal samples were collected to construct a 16S rRNA library and assess fecal short-chain fatty acids (SCFAs). KEY FINDINGS: High-dose SG031 administration yielded reduced depression-like responses and enhanced social interaction in behavioral tests. It also exhibited a protective effect against stress-induced sleep disturbance characterized by decreased sleep time, increased awake time, and autonomic dysfunction during sleep. Fecal examination indicated that high-dose SG031 administration exerted beneficial effects on gut health by maintaining the gut microbial abundance, preserving stability of the microbial composition, and enriching the gut with SCFAs, which were associated with improvements in sleep and autonomic function. SIGNIFICANCE: These findings collectively underscore the multifaceted potential of SG031 in addressing mental health and stress-related sleep challenges through the modulation of the gut microbiota.

Expiratory Velopharyngeal Obstruction: Sleep Endoscopy-Guided Treatment Strategies to Prevent Oral Breathing During Sleep.

OBJECTIVE: Obstructive sleep apnea (OSA) is a prevalent disorder, with oral breathing influencing its severity. Expiratory velopharyngeal obstruction (EVO), observed during drug-induced sleep endoscopy (DISE), may contribute to oral breathing in OSA patients. EVO results in obstruction between the pharynx and nasal cavity during expiration. This study aims to identify factors associated with positive EVO during DISE. STUDY DESIGN: Case series. SETTING: Tertiary Medical Center. METHODS: Seventy-two OSA patients underwent clinical evaluation, polysomnography, and DISE, utilizing interventions like intraoral negative airway pressure (iNAP), mouth closure, and oral appliances (OAs) in supine positions with head rotation. The findings, classified under velopharynx, oropharynx, tongue base, epiglottis, included the presence of EVO. RESULTS: The results demonstrated that interventions including mouth closure and iNAP were associated with increased observation of EVO (43.1% and 34.7%) compared to OA (20.1%). However, head rotation was associated with decreased presence of EVO during DISE compare to supine (26% vs 35.8%). Noticeably, per 1 year increase of age was associated with an increased odds of EVO (odds ratio: 1.03, 95% confidence interval: 1.01-1.06). However, no other baseline characteristics were significantly associated the odds of EVO. CONCLUSION: Our study reveals the effectiveness of head rotation and OA in reducing EVO and improving mouth breathing in OSA patients, offering valuable insights for future treatment strategies.