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Voluntary breathing (VB), short–term exercise (STE), and mental stress (MS) can modulate breathing rate (BR), heart rate (HR), and blood pressure (BP), thereby affecting human physical and mental state. While existing experimental studies have explored the relationship between VB, STE, or MS and BR, HR, and BP changes, their findings remain fragmented due to individual differences and challenges in simultaneous, BR, HR, and BP measurements. We propose a computational approach for in–silico simultaneous measurements of the physiological values by comprehensive prediction of the respiratory and circulatory system responses to VB, STE, or MS. Our integrated model combines a respiratory system with a circulatory model, leveraging actor–critic reinforcement learning to control respiratory muscles. We introduce specific parameters to account for involuntary or VB and hyperventilation induced by STE. We modeled mental stress as an electrical input to the amygdala based on prior studies indicating that stress leads to amygdala hyperactivity. Our predictions for breathing rate (BR), tidal volume, minute ventilation, HR, and BP are validated against literature data obtained during various conditions, including different VB patterns (ranging from 6 to 14 bpm), active or passive knee flexion STE, and MS load. The model demonstrates good agreement with experimental results and highlights its ability to explore the mechanism of individual differences. Our model predicts heart rate variability (HRV) indices of total power spectral density and the ellipse area of Poincaré plot. Notably, slow deep breathing at a BR of 6 bpm increases HRV indices, promoting relaxation and cognitive performance. Conversely, MS elevates BP but reduces HRV indices, indicating an unstable and risky state for mental and physical health. Overall, our proposed computational approach provides simultaneous and reasonable predictions of various physiological values, accounting for individual variations through specific parameters. Author summary: The impact of changes in physical or mental state on physiological parameters, such as heart rate and blood pressure, remains uncertain due to inter–individual variability and challenges in simultaneous measurements. We propose a novel computational model for predicting respiratory and circulatory responses to voluntary breathing, short–term exercise, or mental stress. We introduce specific parameters to account for involuntary or voluntary breathing and hyperventilation induced by short–term exercise. We modeled mental stress as an electrical input to the amygdala based on prior studies indicating that stress leads to amygdala hyperactivity. The model reproduced the respiratory and circulatory states during active or passive short–term exercises, voluntary breathing control, and mental stress loads. The proposed computational approach enables simultaneous and reasonable prediction of diverse physiological values, accounting for individual differences through specific parameters, during voluntary breathing, short–term exercise, or mental stress. This approach also enables substantial prediction of cognitive performance and states for mental and physical health through the physiological values and heart rate variability indices of total power spectral density and the ellipse area of Poincaré plot. [ABSTRACT FROM AUTHOR]

Aim: This study aimed to compile data on the effectiveness of music therapy for patients undergoing cardiothoracic surgery. Background: After cardiac and thoracic surgery, patients often experience physiological and psychological complications, such as anxiety, pain, stress, depression and changes in vital signs, which have a great impact on prognosis. Methods: A systematic search of six databases was performed to identify randomized controlled trials investigating music therapy and cardiothoracic surgery. The data were extracted from the qualified research, the data without heterogeneity were analysed by random-effects model (REM) meta-analysis, and the data with heterogeneity were analysed by fixed-effects model (FEM) meta-analysis. We evaluated anxiety, pain, duration of mechanical ventilation, hospital length of stay, stress hormones, opioid consumption, and vital signs, including heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), diastolic blood pressure (DBP), and systolic blood pressure (SBP) after cardiothoracic surgery. The meta-analysis and sensitivity analysis were performed with RevMan 5.4 and Stata 14 software, and trial sequential analysis was conducted using TSA 0.9.5.10 Beta software. This study was conducted in accordance with the PRISMA guidelines and was registered with PROSPERO. Results: The study included 24 randomized controlled trials with a total of 1576 patients. Our analysis showed that music therapy can significantly reduce the anxiety scores (SMD= -0.74, 95% CI [-0.96, -0.53], p < 0.01) and pain scores (SMD= -1.21, 95% CI [-1.78, -0.65], p < 0.01) of patients after cardiothoracic surgery. Compared with the control group, music therapy dramatically raised postoperative SpO2 (SMD = 0.75, 95% CI [0.11, 1.39], p = 0.02). In addition, the experimental group had significant statistical significance in reducing HR, SBP and opioid consumption. However, there was no significant difference in respiratory rate, stress hormones, diastolic blood pressure, length of hospital stay, or the duration of mechanical ventilation between the two groups. Conclusions: Music therapy can significantly reduce anxiety, pain, HR, SBP, and postoperative opioid use and even improve SpO2 in patients who undergo cardiothoracic surgery. Music therapy has a positive effect on patients after cardiothoracic surgery with few side effects, so it is promising for use in clinics. Trial registration: RROSPERO (registration number: CRD42023424602). [ABSTRACT FROM AUTHOR]

Heart rate variability (HRV) is a useful method to study the autonomic nervous system (ANS) status. As measuring devices have developed and become smaller, many researchers have become interested in the possibilities to implement the method for diving medicine research. The aim of this study was to review human ANS responses in cold water diving (water temperature <5°C), and to comprise the current knowledge of HRV studies in diving and hyperbaric exposure into one review article. A literature search was conducted on 5 Decemberth 2022, with the search terms "HRV" or "heart rate variability" and "diving" or "diver" or "divers", with search functions of the data bases PubMed and Ovid Medline. Peer reviewed original articles, review articles and case reports were accepted to this review. Twenty-six articles met the pre-defined criteria and were included in this review. Studies from very cold water conditions were rare, but suggested that cold strengthens the ANS responses of diving – especially parasympathetic nervous system (PNS) activity due to the trigeminocardiac reflex and baroreceptor and cardiac stretch receptor activity, caused cold and pressure-induced centralisation of the blood. Overall, studies showed predominant PNS activity when putting the face in water, during immersion and when ambient pressure increased. [ABSTRACT FROM AUTHOR]

Deep breathing exercises are the second most used complementary health approach in the United States. Two heart rate variability (HRV) parameters, the root mean square of successive differences (RMSSD) and the respiratory sinus arrhythmia (RSA), are used to assess parasympathetic reactivity to deep breathing, but they are often not in agreement. Our purpose was to determine the cause of the disagreement. We investigated HRV parameters in 38 subjects during baseline, deep breathing, and recovery. Here we show that RMSSD as a measure of parasympathetic reactivity is unreliable; it does not reflect the increase in HRV during deep breathing as determined by RSA. We observed a decrease in RMSSD values despite a marked increase in HRV as determined by RSA and the standard deviation of normal heartbeat interval (SDNN) in healthy subjects and patients with functional bowel disorders. We show that RSA captures all aspects of HRV, whereas successive differences in heart rate intervals are only a small part of HRV, with decreasing variability during deep breathing in most subjects. We present a new measure of calculating RSA during deep breathing that may become an essential tool for researchers and clinicians. We also provide a unique visualization of the increased heart rate variability during deep breathing. Hence, RMSSD cannot be used to assess parasympathetic reactivity during deep breathing; using RSA is recommended. The use of RMSSD in previous influential studies may have led to erroneous conclusions about parasympathetic reactivity during deep breathing. Its continued use may undervalue the effects of the autonomic nervous system in slow deep breathing. [ABSTRACT FROM AUTHOR]

Hyperoxia has been described to induce bradycardia by direct stimulation of the parasympathetic nervous system. Also, hyperoxia has been found to increase blood pressure by an elevation of vascular resistance. However, the latter effect itself would induce bradycardia by baroreceptor stimulation. This single-arm monocentric retrospective study aims to evaluate the correlation between these effects by investigating the relation between oxygen (O2) administration and heart rate over time. Data were collected from 23 patients without cardiovascular problems undergoing hyperbaric oxygen therapy (2.4 bar) retrospectively. During single oxygen bouts, transcutaneously measured partial pressure of O2 was increased. During this surge of oxygen pressure, the arterial blood pressure was increased while the heart rate was decreased. Respiration rate was maintained independently from breathing 100% O2 or air. During single oxygen bouts, the half-life of transcutaneously measured partial pressure of O2 was 5.4 ± 2.1 mmHg/s, and the half-life of heart rate was 0.45 ± 0.19 beats/min. It has been shown that hyperbaric oxygen therapy increases the transcutaneously measured partial pressure of O2. This increase was rather fast, followed by a rather slow decrease in HR. This finding does not support direct vagal activation. Heart rate is not decreased due to a direct vagal activation during hyperbaric oxygen therapy. Our single-arm, retrospective study has additionally confirmed that oxidative stress injures the endothelium, and the reduced endothelial-derived vasodilators cause vasoconstriction. As a consequence, blood pressure increases, and heart rate is then further decreased via the baroreceptor reflex. [ABSTRACT FROM AUTHOR]

Introduction: Scuba diving likely has an impact on the autonomic nervous system (ANS). In the course of conducting trials of underwater ECG recording for measurement of heart rate variability, there was an unexpected stressful event; one participant’s regulator iced and began to free-flow. Methods: A custom-made, water- and pressure-tight aluminum housing was used to protect a portable Holter monitor. ECGs were recorded in three experienced divers who witnessed an unplanned moderately stressful incident during diving. The ECG signals were analysed for measures of heart rate variability (HRV). Results: Analysis for different short-term HRV measures provided consistent results if periods of interest were appropriately time-aligned. There was improvement in sympatho-vagal balance. One diver unexpectedly exhibited an increase in both sympathetic and vagal activity shortly after the incident. Conclusions: A conventional open-water dive affected the ANS of experienced recreational divers as measured by HRV which provides a global evaluation of the ANS and alterations in its two branches. The heart rate variability data gathered from several participating divers around the time of this event illustrate the potential utility of this variable in quantifying stress during diving. HRV data may be useful in addressing relevant diving related questions such as effects of cold, exercise or different breathing gases on ANS function. [ABSTRACT FROM AUTHOR]

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Introduction: The influence of acute exercise on sensory sensitivity (SS) differs according to the type and duration of exercise performed. In the present study, we assessed changes on SS soon after a maximal dynamic apnoea. Methods: Thirty-nine experienced male breath-hold divers were recruited. Critical flicker fusion frequency (CFFF) thresholds were used to measure SS. Thresholds were determined before and after a maximal dynamic apnoea. Immediately after surfacing, heart rate and oxygen saturation (SpO2) were recorded for two minutes. Results: After maximal dynamic apnoea, SpO2 was significantly decreased (from mean 97.3% pre-dive to mean 63.1% postdive; P < 0.0001; η² P = 0.86), but this acute hypoxaemia did not trigger changes in SS (post-dive value 102% of baseline; P = 0.22; η² P = 0.03). Pearson correlation analysis revealed a moderate association between SS with swimming speed (r = 0.423) and apnoea time (r = -0.404). Conclusions: A maximal dynamic apnoea did not produce changes in central nervous system fatigue or cortical arousal. We found no relationship between the hypoxaemia level reached after a maximal apnoea and changes in the CFFF thresholds. This study suggests that the time of exposure to hypoxia during a maximal voluntary apnoea is not enough to produce changes in SS. [ABSTRACT FROM AUTHOR]

The article discusses a study related to assessment and comparison of heart rate variability (HRV) status of women with higher body mass index (BMI) and women with normal BMI. It mentions results showing predominance of sympathetic activity in young overweight and obese females. It also mentions a reduced HRV in healthy young females who are overweight and obese.

Methods to predict onset of cardiopulmonary (CP) decompression sickness (DCS) would be of great benefit to clinicians caring for stricken divers. Principal dynamic mode (PDM) analysis of the electrocardiogram has been shown to provide accurate separation of the sympathetic and parasympathetic tone dynamics. Nine swine (Sus scrofa) underwent a 15-h saturation dive at 184 kPa (60 ft. of saltwater) in a hyperbaric chamber followed by dropout decompression, whereas six swine, used as a control, underwent a 15-h saturation dive at 15 kPa (5 ft. of saltwater). Noninvasive electrocardiograms were recorded throughout the experiment and autonomic nervous system dynamics were evaluated by heart rate series analysis using power spectral density (PSD) and PDM methods. We observed a significant increase in the sympathetic and parasympathetic tones using the PDM method on average 20 min before DCS onset following a sudden induction of decompression. Parasympathetic activities remained elevated, but the sympathetic modulation was significantly reduced at onset of cutis and CP DCS signs, as reported by a trained observer. Similar nonsignificant observations occurred during PSD analysis. PDM observations contrast with previous work showing that neurological DCS resulted in a >50% reduction in both sympathetic and parasympathetic tone. Therefore, tracking dynamics of the parasympathetic tones via the PDM method may allow discrimination between CP DCS and neurological DCS, and this significant increase in parasympathetic tone has potential use as a marker for early diagnosis of CP DCS. [ABSTRACT FROM AUTHOR]

With this study we wanted to test the hypothesis that individual like and dislike as occurring in relation to brand attitude can be objectively assessed. First, individuals rated common brands with respect to subjective preference. Then, they volunteered in an experiment during which their most liked and disliked brand names were visually presented while three different objective measures were taken. Participant's eye blinks as responses to acoustic startle probes were registered with electromyography (EMG) (i) and their skin conductance (ii) and their heart rate (iii) were recorded. We found significantly reduced eye blink amplitudes related to liked brand names compared to disliked brand names. This finding suggests that visual perception of liked brand names elicits higher degrees of pleasantness, more positive emotion and approach-oriented motivation than visual perception of disliked brand names. Also, skin conductance and heart rate were both reduced in case of liked versus disliked brand names. We conclude that all our physiological measures highlight emotion-related differences depending on the like and dislike toward individual brands. We suggest that objective measures should be used more frequently to quantify emotion-related aspects of brand attitude. In particular, there might be potential interest to introduce startle reflex modulation to measure emotion-related impact during product development, product design and various further fields relevant to marketing. Our findings are discussed in relation to the idea that self reported measures are most often cognitively polluted. [ABSTRACT FROM AUTHOR]

Adaptation of action potential duration (APD) to pacing cycle length (CL) has been previously characterized in isolated cardiomyocytes for sudden changes in constant CL and for pre-/postmature stimuli following constant pacing trains. However, random fluctuations characterize both physiological sinus rhythm (up to 10% of mean CL) and intrinsic beat-to-beat APD at constant pacing rate. We analysed the beat-to-beat sensitivity of each APD to the preceding CL during constant–sudden, random or linearly changing pacing trains in single patch clamped rat left ventricular myocytes, in the absence of the autonomic and electrotonic effects that modulate rate dependency in the intact heart. Beat-to-beat variability of APD at −60 mV (APD−60 mV), quantified ass.d. over 10-beat sequences, increased with corresponding mean APD. When measured as coefficient of variability (CV), APD−60 mV variability was inversely proportional to pacing frequency (from 1.2% at 5 Hz to 3.2% at 0.2 Hz). It was increased, at a basic CL (BCL) of 250 ms, by 55% by the L-type calcium current ( ICaL) blocker nifedipine, and decreased by 23% by the transient-outward potassium current ( Ito) blocker 4-aminopyridine. Variability of APD at BCL of 250 ms prevented the detection of random changes of CL smaller than ∼5%. Ten per cent random changes in CL were detected as a 40% increase in CV of APD and tended to correlate with it ( r= 0.43). Block of ICaL depressed this correlation ( r= 0.23), whereas block of Ito significantly increased it ( r= 0.67); this was similar with linearly changing CL ramps (ranging ±10% and ±20% of 250 ms). We conclude that beat-to-beat APD variability, a major determinant of the propensity for development of arrhythmia in the heart, is present in isolated myocytes, where it is dependent on mean APD and pacing rate. Action potential duration shows a beat-to-beat positive correlation with preceding randomly/linearly changing CL, which can be pharmacologically modulated. [ABSTRACT FROM AUTHOR]

Mitral annular (MA) excursion during diastole encompasses a volume that is part of total left ventricular (LV) filling volume (LVFV). Altered excursion or area variation of the MA due to changes in preload or inotropic state could affect LV filling. We hypothesized that changes in LV preload and inotropic state would not alter the contribution of MA dynamics to LVFV. Six sheep underwent marker implantation in the LV wall and around the MA. After 7-10 days, biplane fluoroscopy was used to obtain three-dimensional marker dynamics from sedated, closed-chest animals during control conditions, inotropic augmentation with calcium (Ca), preload reduction with nitroprusside (N), and vena caval occlusion (VCO). The contribution of MA dynamics to total LVFV was assessed using volume estimates based on multiple tetrahedra defined by the three-dimensional marker positions. Neither the absolute nor the relative contribution of MA dynamics to LVFV changed with Ca or N, although MA area decreased (Ca, P < 0.01; and N, P < 0.05) and excursion increased (Ca, P < 0.01). During VCO, the absolute contribution of MA dynamics to LVFV decreased (P < 0.001), based on a reduction in both area (P < 0.001) and excursion (P < 0.01), but the relative contribution to LVFV increased from 18 ± 4 to 45 ± 13% (P < 0.001). Thus MA dynamics contribute substantially to LV diastolic filling. Although MA excursion and mean area change with moderate preload reduction and inotropic augmentation, the contribution of MA dynamics to total LVFV is constant with sizeable magnitude. With marked preload reduction (VCO), the contribution of MA dynamics to LVFV becomes even more important. [ABSTRACT FROM AUTHOR]

Stress ulcer is clinically prevalent, but the underlying mechanisms are not well understood. This study aimed to investigate the role of sympathovagal imbalance in the development of water immersion restraint stress (WRS)-induced gastric mucosal lesion. Wistar rats were subjected to either restraint stress (RS) (n = 7) or WRS (n = 7) for 5 h. Linear parameters of heart rate variability and Poincaré plot were analyzed on the basis of the surface ECGs. Gastric mucosal lesion was evaluated by gross anatomy and histology. Mean R-R intervals significantly increased (P < 0.001) in a time-dependent manner in the WRS group but slightly decreased (P < 0.001) in the RS group. Root mean square of successive differences of R-R intervals and high-frequency norm (high-frequency power normalized by the total frequency power) were significantly higher in the WRS group than the RS group (P < 0.001). Low-frequency norm and low-to-high-frequency ratio increased significantly 1 h after stress and then declined to similar levels in both groups. The Poincaré plots of R-R intervals in the WRS group shifted right-upwardly and showed dispersed patterns compared with the RS group. Gastric mucosae showed serious hemorrhage, effusion, and structural collapse in the WRS group but remained normal in the RS group. Bilateral cervical vagotomy suppressed the increase of heart rate variability and prevented the gastric mucosal lesion induced by WRS. We conclude that parasympathetic overactivity is the predominant autonomic response to WRS and is most probably the leading mechanism of WRS-induced gastric mucosal lesion in rat. [ABSTRACT FROM AUTHOR]