Voluntary Breathing Research Articles

Chapter 6 - Critical roles for breathing in the genesis and modulation of emotional states

Breathing can be classified into metabolic and behavioral categories. Metabolic breathing and voluntary behavioral breathing are controlled in the brainstem and in the cerebral motor cortex, respectively. This chapter places special emphasis on the reciprocal influences between breathing and emotional processes. As is the case with neural control of breathing, emotions are generated by multiple control networks, located primarily in the forebrain. For several decades, a respiratory rhythm generator has been investigated in the limbic system. The amygdala receives respiratory-related input from the piriform cortex. Excitatory recurrent branches are located in the piriform cortex and have tight reciprocal synaptic connections, which produce periodic oscillations, similar to those recorded in the hippocampus during slow-wave sleep. The relationship between olfactory breathing rhythm and emotion is seen as the gateway to interpreting the relationship between breathing and emotion. In this chapter, we describe roles of breathing in the genesis of emotion, neural structures common to breathing and emotion, and mutual importance of breathing and emotion. We also describe the central roles of conscious awareness and voluntary control of breathing, as effective methods for stabilizing attention and the contents in the stream of consciousness. Voluntary control of breathing is seen as an essential practice for achieving emotional well-being.

Physiological Effects of Cryptic Ancient Religious Chants

Aim: One of the variables that contributes to higher academic achievement is awareness. In Indian schools, traditional practises are applied to improve mental skills with the purpose of adding value. Prayers and other mantras, for example, can help to regulate and enhance the cardiovascular heart's rhythm while also modifying baroreflex sensitivity.
 Method: 50 healthy individuals were selected for the study. Comparisons of the effects of reciting Mary's petitions or mantra during voluntary breathing and metronome device control on rate of respiration, spontaneous pulse, blood pressure, and brain circulation in the RR region. The purpose of this study is to compare the impact of singing the Gayatri mantra (GM) on awareness to the function of letter substitution (DLST). Respiratory frequency, normal breathing, baroreflex sensitivity, heart oscillation frequency were recorded. The Bonferroni adjustment was utilised in the frequent measurement analysis of difference.
 Conclusion: With the DLST net, both of these times showed complete upgrades in total points. In comparison to PL (3.85 percent), the extent of the development of net points was large after GM (22.67 percent). When repeated seven times per minute, both prayers and mantras generate a noticeable, forceful, and simultaneous rise in present-time cardiovascular system pulsations. The sensitivity of the baroreflex also increases significantly, from 9.2 (SD 4.4) to 11.7 (4.5) ms/mm Hg, P0.06.

Heart Rate Variability Peculiarities in Adolescents with Psychopathology in the Educational Environment

Under conditions of inclusive education, students with health limitations, in particular, children with neurological and mental disorders, have the opportunity to study at a general school. The goal of this study was to assess the possibility of using analysis of heart rate variability (HRV) as a relatively simple tool for evaluation of the adaptive resources in students with mental disorders and for early detection of dysfunctions in the neuroregulatory mechanisms in healthy students. We compared the spectral parameters of HRV and peripheral blood pressure in healthy adolescents (n = 70) and adolescents with neuropsychiatric disorders (n = 58). Electrocardiogram was recorded for 2 minutes in a sitting posture, wearing a spirometric mask with voluntary breathing. Adolescents with mental disorders demonstrated a high total power of the HRV spectrum, an increased high-frequency power (0.15–0.4 Hz), a decreased low frequency / high-frequency ratio, and reduced total power and low frequency spectral power of systolic blood pressure variability. The revealed differences were observed mainly in males. The presented data demonstrate an increased vagal tone in adolescents with mental disabilities. Our findings support the idea that HRV can be used in schools to identify risk groups of vulnerability to mental disorders.

Capnometric feedback training decreases 24-h blood pressure in hypertensive postmenopausal women

BackgroundHigh normal resting pCO2 is a risk factor for salt sensitivity of blood pressure (BP) in normotensive humans and has been associated with higher resting systolic BP in postmenopausal women. To date, however, no known studies have investigated the effects of regular practice of voluntary mild hypocapnic breathing on BP in hypertensive patients. The objective of the present research was to test the hypothesis that capnometric feedback training can decrease both resting pCO2 and 24-h BP in a series of mildly hypertensive postmenopausal women.MethodsA small portable end tidal CO2 (etCO2) monitor was constructed and equipped with software that determined the difference between the momentary etCO2 and a pre-programmed criterion range. The monitor enabled auditory feedback for variations in CO2 outside the criterion range. 16 mildly hypertensive postmenopausal women were individually trained to sustain small decreases in etCO2 during six weekly sessions in the clinic and daily sessions at home. 24-h BP monitoring was conducted before and after the intervention, and in 16 prehypertensive postmenopausal women in a control group who did not engage in the capnometric training.ResultsFollowing the intervention, all 16 capnometric training participants showed decreases in resting etCO2 (− 4.3 ± 0.4 mmHg; p < .01) while 15 showed decreases in 24-h systolic BP (− 7.6 ± 2.0 mmHg; p < .01). No significant changes in either measure was observed in the control group. In addition, nighttime (− 9.5 ± 2.6; p < .01) and daytime (− 6.7 ± 0.2 mmHg) systolic BP were both decreased following capnometric training, while no significant changes in nighttime (− 2.8 ± 2.2 mmHg; p = .11) or daytime (− 0.7 ± 1.0 mmHg; p ≤ .247) systolic BP were observed in the control group.ConclusionsThese findings support the hypothesis that regular practice of mild hypocapnic breathing that decreases resting etCO2 reliably decreases 24-h blood pressure in hypertensive postmenopausal women. The extent to which these effects persist beyond the training period or can be observed in other hypertensive subgroups remains to be investigated.

Effects of Voluntary Slow Breathing on Vagally-Mediated Heart Rate Variability: A Systematic Review

Previous findings suggest that impulsivity is related to chronic low-grade inflammation. Inflammation is known to trigger the kynurenine pathway to a pathological level in various impulsivity-related disorders. Nonetheless, murine models and recent human studies have shown that physical exercise, in particular High Intensity Interval Training (HIIT), could counterbalance the negative effects of inflammation on the kynurenine pathway.This study evaluates the effects of eight weeks of HIIT versus an active control group on impulsivity levels and accompanying alterations of inflammatory-mediated changes of the kynurenine pathway in a sample of emotionally impulsive humans.Participants were randomly allocated to either HIIT or stretching conditions (three trainings per week for eight weeks). Fitness level was evaluated via VO2peak values at the beginning at end of the intervention. Kynurenine metabolites, pro-inflammatory cytokines, and impulsivity levels were evaluated at T0, T4, and T8 weeks. Statistical analyses were performed using mixed models.Fifty-three participants were included in the modified Intention To Treat analysis (45 finished the intervention). The HIIT group (n = 28) largely increased the aerobic fitness of its participants and produced physiological changes while the stretching group (n = 25) did not. HIIT reduced interleukin 6 levels (small to moderate interaction) and reduced the activity of the neurotoxic branch of the kynurenine pathway (small to moderate interaction for KYNA/QA and KYN/QA) after eight weeks of training while the active control did not change. Both interventions were effective to decrease emotion-related impulsivity, however only the HIIT group decreased participants’ emotion-unrelated levels. Changes in emotion-related and -unrelated impulsivity were moderately correlated to changes in KYNA/KYN.This study demonstrated that HIIT was able to switch the kynurenine pathway from its neurotoxic branch to its neuroprotective one. This shift was associated with a decrease in impulsivity. Based on these findings, future work may consider investigating more intensively the effect of HIIT on impulsivity-related disorders.

Use of noninvasive volume assessment methods to predict acute blood loss in spontaneously breathing volunteers.

ObjectiveThe use of noninvasive volume assessment methods to predict acute blood loss in spontaneously breathing patients remains unclear. We aimed to investigate changes in the pleth variability index (PVI), vena cava collapsibility index (VCCI), end-tidal carbon dioxide (EtCO2), pulse pressure (PP), and mean arterial pressure (MAP) in spontaneously breathing volunteers after acute loss of 450 mL blood and passive leg raise (PLR).MethodsThis prospective observational study enrolled healthy volunteers in the blood donation center of an academic hospital. We measured the PVI, EtCO2, VCCI, MAP, and PP before blood donation; at the 0th and 10th minute of blood donation; and after PLR. The primary outcome was the changes in PVI, EtCO2, VCCI, MAP, and PP.ResultsWe enrolled thirty volunteers. There were significant differences among the four obtained measurements of the PVI, EtCO2, and MAP (P<0.001, P<0.001, P<0.001, respectively). Compared to the predonation values, post-hoc analysis revealed an increase in the PVI at the 0th min postdonation (mean difference [MD], 5.4±5.9; 95% confidence interval [CI], -7.6 to -3.1; P<0.001); a decrease in the EtCO2 and MAP at the 0th and 10th minute postdonation, respectively (MD, 2.4±4.6; 95% CI, 0.019 to 4.84; P=0.008 and MD, 6.4±6.4; 95% CI, 3 to 9.7; P<0.001, respectively). Compared with EtCO2 at the 10th minute, the value increased after PLR (MD, 1.8±3.2; 95% CI, 0.074 to 4.44; P=0.006).ConclusionThe PVI and EtCO2 could detect early hemodynamic changes after acute blood loss. However, it remains unclear whether they can determine volume status in spontaneously breathing patients.

Cerebrovascular Reactivity Mapping Without Gas Challenges: A Methodological Guide.

Cerebrovascular reactivity (CVR) is defined as the ability of vessels to alter their caliber in response to vasoactive factors, by means of dilating or constricting, in order to increase or decrease regional cerebral blood flow (CBF). Importantly, CVR may provide a sensitive biomarker for pathologies where vasculature is compromised. Furthermore, the spatiotemporal dynamics of CVR observed in healthy subjects, reflecting regional differences in cerebral vascular tone and response, may also be important in functional MRI studies based on neurovascular coupling mechanisms. Assessment of CVR is usually based on the use of a vasoactive stimulus combined with a CBF measurement technique. Although transcranial Doppler ultrasound has been frequently used to obtain global flow velocity measurements, MRI techniques are being increasingly employed for obtaining CBF maps. For the vasoactive stimulus, vasodilatory hypercapnia is usually induced through the manipulation of respiratory gases, including the inhalation of increased concentrations of carbon dioxide. However, most of these methods require an additional apparatus and complex setups, which not only may not be well-tolerated by some populations but are also not widely available. For these reasons, strategies based on voluntary breathing fluctuations without the need for external gas challenges have been proposed. These include the task-based methodologies of breath holding and paced deep breathing, as well as a new generation of methods based on spontaneous breathing fluctuations during resting-state. Despite the multitude of alternatives to gas challenges, existing literature lacks definitive conclusions regarding the best practices for the vasoactive modulation and associated analysis protocols. In this work, we perform an extensive review of CVR mapping techniques based on MRI and CO2 variations without gas challenges, focusing on the methodological aspects of the breathing protocols and corresponding data analysis. Finally, we outline a set of practical guidelines based on generally accepted practices and available data, extending previous reports and encouraging the wider application of CVR mapping methodologies in both clinical and academic MRI settings.

Differential responses to breath-holding, voluntary deep breathing and hypercapnia in left and right dorsal anterior cingulate.

What is the central question of this study? What is the role of dorsal anterior cingulate cortex (ACC) in respiration control in humans? What is the main finding and its importance? Direct evidence is provided for a role of the ACC in respiratory control in humans. The neurophysiological responses in dorsal ACC to different breathing tasks varied and were different between left and right ACC. The role of subcortical structures and cerebral cortex in the maintenance of respiratory homeostasis in humans remains poorly understood. Emerging evidence suggests an important role of the anterior cingulate cortex (ACC) in respiratory control. In this study, local field potentials (LFPs) from dorsal ACC were recorded in humans through implanted deep brain electrodes during several breathing activities, including voluntary activities of breath-holding and deep breathing, and involuntary activities of inspiration of varying concentrations of carbon dioxide (1%, 3%, 5% and 7%). We found that the breath-holding task induced significant unilateral left-sided ACC changes in LFP power, including an increased activity in lower frequency bands (3-5Hz) and decreased activity in higher frequency bands (12-26Hz). The respiratory task involving reflex increase in ventilation due to hypercapnia (raised inspired CO2 ) was associated with bilateral changes in activity of the ACC (again with increased activity in lower frequency bands and reduced activity in higher frequency bands). The voluntary breathing task with associated hypocapnia (deep breathing) induced bilateral changes in activity within low frequency bands. Furthermore, probabilistic diffusion tractography analysis showed left-sided connection of the ACC with the insula and frontal operculum, and bilateral connections within subsections of the cingulate gyrus and the thalamus. This electrophysiological analysis provides direct evidence for a role of the ACC in respiratory control in humans.

Priming the cardiodynamic phase of pulmonary oxygen uptake through voluntary modulations of the respiratory pump at the onset of exercise.

What is the central question of this study? The initial increase in oxygen uptake ( ) at exercise onset results from pulmonary perfusion changes secondary to an increased venous return. Breathing mechanics contribute to venous return through abdominal and intrathoracic pressures variation. Can voluntary breathing techniques (abdominal or rib cage breathing) increase venous return and improve at exercise onset? What is the main finding and its importance? Abdominal and rib cage breathing increase venous return and at exercise onset. This mechanism could be clinically relevant in patients with impaired cardiac function limiting oxygen transport. We examined how different breathing patterns can modulate venous return and alveolar gas transfer during exercise transients in humans. Ten healthy men transitioned from rest to moderate cycling while breathing spontaneously (SP) or with voluntary increases in abdominal (AB) or intrathoracic (RC) pressure swings. We used double body plethysmography to determine blood displacements between the trunk and the extremities (Vbs ). From continuous signals of airflow and O2 fraction, we calculated breath-by-breath oxygen uptake at the mouth and used optoelectronic plethysmography to correct for lung O2 store changes and calculate alveolar O2 transfer ( ). Oesophageal (Poes ) and gastric (Pga ) pressures were monitored using balloon-tipped catheters. Cardiac stroke volume was measured using impedance cardiography. During the cardiodynamic phase (Φ1) of -on kinetics (20s following exercise onset), AB and RC increased total alveolar oxygen transfer compared to SP (227±32, P=0.019 vs. 235±27, P=0.001 vs. 206±20ml, mean±SD). Pga and Poes swings increased with AB (by 24.4±9.6cmH2 O, P<0.001) and RC (by 14.5±5.7cmH2 O, P<0.001), respectively. AB yielded a greater increase in intra-breath Vbs swings compared with RC and SP (+0.30±0.14 vs. +0.16±0.11, P<0.001 vs. +0.10±0.05ml, P=0.006) and increased the sum of stroke volumes compared to SP (4.47±1.28 vs. 3.89±0.96litres, P=0.053), while RC produced significant central blood translocation from the extremities compared with SP (by 493±311ml, P<0.001). Our findings indicate that combining exercise onset with AB or RC increases venous return, thus increasing mass oxygen transport above metabolic consumption during Φ1 and limiting the oxygen deficit incurred.

Показатели вариабельности сердечного ритма и артериального давления у подростков с нервно-психическими нарушениями при выполнении нагрузочных проб

Целью настоящего исследования стало изучение особенностей вариабельности сердечного ритма (СР) и вариабельности артериального давления (АД) у подростков с клинически-подтверждённой нервно-психической патологией, при регистрации в условиях функциональной нагрузочной пробы. Методы. Методом спироартериокардиоритмографии проведено тестирование показателей сердечно-сосудистой системы в условиях функциональной нагрузочной пробы (в надетой спирометрической маске, с произвольным дыханием - модель лёгкой гиперкапнии/гипоксии) у учащихся специализированной школы для пациентов психиатрических клиник (на стадии ремиссии) (n = 61), и учащихся общеобразовательной школы (n = 197). Подростки из специализированной школы были разделены на две группы: пациенты с неврологическими диагнозами и последствиями органических поражений мозга (n = 35); пациенты с психическими расстройствами без органических поражений мозга (n = 26). Возраст учащихся из обеих школ составил 12,0-17,7 лет, выборки обеих школ были поделены на 5 возрастных диапазонов (12,0-13,5, 13,6-14,5, 14,6-15,5, 15,6-16,5 и 16,6-17,7 лет). В контрольной школе подростки были дополнительно разделены по полу. Результаты. В возрастных диапазонах 12,0-13,5, 13,6-14,5 и 14,6-15,5 лет статистически значимых различий между учащимися разных школ ни по одному показателю не обнаружено. В возрастном диапазоне 15,6-16,5 лет выявлены более высокие величины систолического и диастолического АД у подростков с неврологическими диагнозами и последствиями органических поражений мозга (по сравнению с контрольными группами). В возрастном диапазоне 16,6-17,7 лет у подростков с психическими расстройствами без органических поражений мозга обнаружены более высокие (по сравнению с контролем) величины стресс-индекса и более низкие (по сравнению с пациентами с неврологическими диагнозами) величины чувствительности спонтанного артериального барорефлекса (на уровне тенденции, p = 0,056). Заключение. Проведённые исследования показали, что по параметрам вариабельности СР и АД подростки с нервно-психической патологией не существенно отличаются от учащихся общеобразовательных школ. Повышение стресс-индекса у подростков с психопатологией без органических поражений мозга в возрасте 16,6-17,7 лет можно интерпретировать как коррелят повышения симпатической активности. У подростков с неврологическими заболеваниями, по-видимому, обнаружена более ранняя по сравнению с контролем манифестация юношеской предгипертензии (в 15,6-16,5 лет). The aim of this study was to assess characteristics of heart rate (HR) and blood pressure (BP) variability in adolescents with clinically confirmed neuropsychiatric pathology in the conditions of a functional test. Methods. The method of spiroarteriocardiorhythmography was used to test cardiovascular parameters during a functional stress test (voluntary breathing with a spirometric mask, a model of mild hypercapnia / hypoxia), in students of a specialized school for patients of psychiatric clinics (in remission) (n = 61) and students of a regular school (n = 197). Adolescents from a specialized school were divided into two groups: 1) patients with neurological diagnoses and consequences of organic brain damage (n = 35) and 2) patients with psychiatric disorders without organic brain damage (n = 26). The age of students from both schools was 12.0-17.7 years; samples of both schools were divided into 5 age ranges (12.0-13.5, 13.6-14.5, 14.6-15.5, 15.6-16.5 and 16.6-17.7 years). The adolescents from the control school were additionally subdivided by gender. Results. In the age ranges of 12.0-13.5, 13.6-14.5, and 14.6-15.5 years, no statistically significant differences were found between students from different schools in any parameters. In the age range of 15.6-16.5 years, adolescents with neurological diagnoses and consequences of organic brain damage had higher values of systolic and diastolic BP compared to the control groups. In the age range of 16.6-17.7 years, adolescents with psychiatric disorders without organic brain damage had higher values of the stress index than in the control groups, and a tendency towards lower values of spontaneous arterial baroreflex sensitivity compared to patients with neurological diagnoses (p = 0.056). Conclusion. Adolescents with neuropsychiatric pathologies did not significantly differ from students of regular schools in parameters of HR and BP variability. The increased stress index in adolescents with psychopathology without organic brain damage aged 16.6-17.7 years can be interpreted as a correlate of elevated sympathetic activity. Adolescents with neurological diseases apparently had an earlier onset of juvenile prehypertension (at 15.6-16.5 years) compared to the control.

Deep correction of breathing-related artifacts in real-time MR-thermometry

Real-time MR-imaging has been clinically adapted for monitoring thermal therapies since it can provide on-the-fly temperature maps simultaneously with anatomical information. However, proton resonance frequency based thermometry of moving targets remains challenging since temperature artifacts are induced by the respiratory as well as physiological motion. If left uncorrected, these artifacts lead to severe errors in temperature estimates and impair therapy guidance.In this study, we evaluated deep learning for on-line correction of motion related errors in abdominal MR-thermometry. For this, a convolutional neural network (CNN) was designed to learn the apparent temperature perturbation from images acquired during a preparative learning stage prior to hyperthermia. The input of the designed CNN is the most recent magnitude image and no surrogate of motion is needed. During the subsequent hyperthermia procedure, the recent magnitude image is used as an input for the CNN-model in order to generate an on-line correction for the current temperature map.The method's artifact suppression performance was evaluated on 12 free breathing volunteers and was found robust and artifact-free in all examined cases. Furthermore, thermometric precision and accuracy was assessed for in vivo ablation using high intensity focused ultrasound. All calculations involved at the different stages of the proposed workflow were designed to be compatible with the clinical time constraints of a therapeutic procedure.

Minimally Invasive Injection to the Phrenic Nerve in a Porcine Hemidiaphragmatic Paralysis Model: A Pilot Study.

Neurodegenerative diseases and spinal cord injury can affect respiratory function often through motor neuron loss innervating the diaphragm. To reinnervate this muscle, new motor neurons could be transplanted into the phrenic nerve (PN), allowing them to extend axons to the diaphragm. These neurons could then be driven by an optogenetics approach to regulate breathing. This type of approach has already been demonstrated in the peripheral nerves of mice. However, there is no established thoracoscopic approach to PN injection. Also, there is currently a lack of preclinical large animal models of diaphragmatic dysfunction in order to evaluate the efficacy of potential treatments. To evaluate the feasibility of thoracoscopic drug delivery into the PN and to assess the viability of hemidiaphragmatic paralysis in a porcine model. Two Landrace farm pigs underwent a novel procedure for thoracoscopic PN injections, including 1 nonsurvival and 1 survival surgery. Nonsurvival surgery involved bilateral PN injections and ligation. Survival surgery included a right PN injection and transection proximal to the injection site to induce hemidiaphragmatic paralysis. PN injections were successfully performed in both procedures. The animal that underwent survival surgery recovered postoperatively with an established right hemidiaphragmatic paralysis. Over the 5-d postoperative period, the animal displayed stable vital signs and oxygenation saturation on room air with voluntary breathing. Thoracoscopic targeting of the porcine PN is a feasible approach to administer therapeutic agents. A swine model of hemidiaphragmatic paralysis induced by unilateral PN ligation or transection may be potentially used to study diaphragmatic reinnervation following delivery of therapeutics.

随意的自発呼吸における肺の機械的エネルギー・機械的仕事量・エネルギー保存率

随意的自発呼吸における肺の機械的エネルギー・機械的仕事量・エネルギー保存率

Influence of Nadi Shodhana Pranayama on respiratory functions of postmenopausal women

Background: Menopause is associated with lower lung functions and more respiratory symptoms. The menopausal transition implies a series of hormonal metabolic and psychological changes in women. They undergo lot of changes during this stage and they seek a change for this. Pranayama is an alternative voluntary breathing exercises reported to manage common postmenopausal symptoms, includes hot flashes, night sweat, shortness of breath, fatigue, pain, and psychological changes. With this background, we took up this study effect of pranayama on respiratory functions of postmenopausal women. Aims and Objectives: The main objective of the study was to investigate the effect of pranayama practice on respiratory functions of postmenopausal women. Materials and Methods: Sixty volunteers were divided into two groups, 30 interventional group and 30 control group. Pranayama group was subjected to pranayama for 12 weeks. The lung function parameters were recorded on Spiro excel, with a computerized spirometer. Five lung function parameters, it is forced vital capacity (FVC), forced expiratory volume in 1st s (FEV1), FEV1/FVC% peak expiratory flow rate, and maximum voluntary ventilation, were recorded before and after intervention in both groups. Results: The analyzed values were significantly improved in the interventional group when compared with the control group. This may be due to maximal inflation and deflation of the lungs which cause increased strength, recruitment, and endurance of respiratory musculature. Conclusion: Nadi Shodhana pranayama can improve respiratory function and can be suggested as an important tool for healthy living in postmenopausal women.

Respiratory Fluctuation of Peak Systolic Velocities in the Carotid Doppler Waveforms of Patients With Obstructive Airway Disease: Evidence of Pulsus Paradoxus With Experimental Validation.

To characterize fluctuations in peak systolic velocities (PSVs) in Doppler waveforms of the carotid artery in patients with and without obstructive airway disease and in volunteers subjected to incremental levels of airway resistance in an experimental model. The PSV variation in common carotid waveforms was measured in 100 patients who had had a carotid ultrasound examination and no respiratory or carotid disease. This was compared to that of patients who had this study during an admission for acute exacerbation of chronic obstructive pulmonary disease (COPD). The PSV variation was correlated with pulmonary function testing. In addition, 14 healthy volunteers were asked to breathe through 5 resistors. Simultaneous recordings were made of Doppler waveforms in the common carotid artery, cardiac activity, and respiration. Peak systolic velocity changes from inspiration to expiration were calculated. Of the 100 patients without respiratory disease, the magnitude of the PSV variation averaged 6.3 cm/s. Of the 33 patients with COPD, the PSV variation averaged 16.5 cm/s. Nineteen of the 33 patients with COPD had concurrent pulmonary function testing; there was a statistically significant correlation between the PSV variation and forced vital capacity and forced expiratory volume indices. For the volunteers, mean velocity changes were 7.1, 6.6, 8.3, 15.1, and 16.1 cm/s for 0.00-, 2.15-, 3.27-, 3.58-, and 5.77-cm H2 O/L/s levels of breathing resistance, respectively. There was a statistically significant relationship between an increasing airway load and the decline in PSV during inspiration (P = .02). The PSV variation is greater in patients with increased airway resistance. Similar changes are evident in volunteers breathing into resistors. These findings likely reflect pulsus paradoxus.

Wearable radio-frequency sensing of respiratory rate, respiratory volume, and heart rate

Many health diagnostic systems demand noninvasive sensing of respiratory rate, respiratory volume, and heart rate with high user comfort. Previous methods often require multiple sensors, including skin-touch electrodes, tension belts, or nearby off-the-body readers, and hence are uncomfortable or inconvenient. This paper presents an over-clothing wearable radio-frequency sensor study, conducted on 20 healthy participants (14 females) performing voluntary breathing exercises in various postures. Two prototype sensors were placed on the participants, one close to the heart and the other below the xiphoid process to couple to the motion from heart, lungs and diaphragm, by the near-field coherent sensing principle. We can achieve a satisfactory correlation of our sensor with the reference devices for the three vital signs: heart rate (r = 0.95), respiratory rate (r = 0.93) and respiratory volume (r = 0.84). We also detected voluntary breath-hold periods with an accuracy of 96%. Further, the participants performed a breathing exercise by contracting abdomen inwards while holding breath, leading to paradoxical outward thorax motion under the isovolumetric condition, which was detected with an accuracy of 83%.

Effect of voluntary breathing exercises on stable coronary artery disease in heart rate variability and rate-pressure product: a study protocol for a single-blind, prospective, randomized controlled trial

BackgroundAt present, China has more than 11 million patients with stable coronary heart disease and this is becoming a major public health problem. The pathological changes of coronary heart disease can lead to dysfunction of the cardiac autonomic nervous system, which increases the risk of complications such as malignant arrhythmia (ventricular flutter, ventricular fibrillation, etc.), heart rate, systolic blood pressure, and rate-pressure product (RPP), which is highly correlated with myocardial oxygen consumption and indirectly reflects myocardial blood supply and oxygen consumption. Although the guidelines recommend that such patients take drugs to reduce heart rate and myocardial oxygen consumption, the clinical control of heart rate is still not ideal. Thus, in this trial, we will use voluntary breathing exercises as the strategy of exercise rehabilitation for patients with stable coronary artery disease (SCAD), in order to increase the vagus nerve activity and/or reduce the sympathetic nervous activity, help maintain or rebuild the balance of plant nerve system, improve the time-domain index of heart rate variability, reduce the burden on the heart, and relieve patients’ anxiety and other negative emotions.MethodsThis is a 6-month single-blind, randomized controlled clinical trial that will be conducted in the First Affiliated Hospital of Soochow University. A total of 140 patients who fill out the Informed Consent Form are registered and randomized 1:1 into the Voluntary Breathing Exercises (VBE)-based clinical trial monitoring group (n = 70) or the Routine follow-up group (n = 70). The VBE-based clinical trial monitoring group is given VBE training on the basis of conventional treatment and health education, while the control group received conventional health education and follow-up. The primary outcomes will be measured heart rate variability and RPP. Secondary outcomes will include changes in Self-rating Anxiety Scale, total cholesterol, triglyceride, high-density lipoprotein, low-density lipoprotein, weight, and body mass index.DiscussionThis trial will carry out scientific respiratory exercise for patients with SCAD, which belongs to the category of active secondary prevention for patients, and changes from remedial to pre-protective. VBE is easy to operate and is not limited by time and place. It is important and meaningful to carry out VBE for patients with SCAD. This study will provide considerable evidence for further large-scale trials and alternative strategies for the rehabilitation nursing of patients with SCAD.Trial registrationChinese Clinical Trials Registry, 1900024043. Registered on 23 June 2019.

Evaluation of Respiratory Muscle Strength and Diaphragm Ultrasound: Normative Values, Theoretical Considerations, and Practical Recommendations

Background: Reference values derived from existing diaphragm ultrasound protocols are inconsistent, and the association between sonographic measures of diaphragm function and volitional tests of respiratory muscle strength is still ambiguous. Objective: To propose a standardized and comprehensive protocol for diaphragm ultrasound in order to determine lower limits of normal (LLN) for both diaphragm excursion and thickness in healthy subjects and to explore the association between volitional tests of respiratory muscle strength and diaphragm ultrasound parameters. Methods: Seventy healthy adult subjects (25 men, 45 women; age 34 ± 13 years) underwent spirometric lung function testing, determination of maximal inspiratory and expiratory pressure along with ultrasound evaluation of diaphragm excursion and thickness during tidal breathing, deep breathing, and maximum voluntary sniff. Excursion data were collected for amplitude and velocity of diaphragm displacement. Diaphragm thickness was measured in the zone of apposition at total lung capacity (TLC) and functional residual capacity (FRC). All participants underwent invasive measurement of transdiaphragmatic pressure (Pdi) during different voluntary breathing maneuvers. Results: Ultrasound data were successfully obtained in all participants (procedure duration 12 ± 3 min). LLNs (defined as the 5th percentile) for diaphragm excursion were as follows: (a) during tidal breathing: 1.2 cm (males; M) and 1.2 cm (females; F) for amplitude, and 0.8 cm/s (M) and 0.8 cm/s (F) for velocity, (b) during maximum voluntary sniff: 2.0 cm (M) and 1.5 cm (F) for amplitude, and 6.7 (M) cm/s and 5.2 cm/s (F) for velocity, and (c) at TLC: 7.9 cm (M) and 6.4 cm (F) for amplitude. LLN for diaphragm thickness was 0.17 cm (M) and 0.15 cm (F) at FRC, and 0.46 cm (M) and 0.35 cm (F) at TLC. Values for males were consistently higher than for females, independent of age. LLN for diaphragmatic thickening ratio was 2.2 with no difference between genders. LLN for invasively measured Pdi during different breathing maneuvers are presented. Voluntary Pdi showed only weak correlation with both diaphragm excursion velocity and amplitude during forced inspiration. Conclusions: Diaphragm ultrasound is an easy-to-perform and reproducible diagnostic tool for noninvasive assessment of diaphragm excursion and thickness. It supplements but does not replace respiratory muscle strength testing.

The Effect of Surgical Patient Positions on Plet Variability Index, Perfusion Index and Noninvasive Continuous Cardiac Output Measurement Method in Voluntary Breathing Volunteers

Amaç: Cerrahi prosedür için verilen farklı pozisyonlar doku perfüzyonunda ve kardiyak outputta değişikliklere neden olabilir. Bu çalışmada spontan solunuma sahip katılımcılarda plet değişkenlik indeksinin (PVI), perfüzyon indeks (PI) ve noninvaziv sürekli kardiyak output ölçüm yöntemi (EscCO) nin farklı cerrahi pozisyonlardaki değişimlerini araştırmayı amaçladık.Materyal ve Metod: 20 katılımcıdan oluşan bir sağlıklı birey grubu prospektif gözlemsel çalışmaya dahil edildi. Sırasıyla Supin, 30 derece baş yukarı, 45 derece baş yukarı, 20 derece Trendelenburg, 20 derece ters-Trendelenburg, ve pron pozisyonları uygulandı. Her pozisyon arası 10 ar dk olacak şekilde süre tutuldu. Her pozisyon değişikliğinden önce gönüllüler sırtüstü pozisyona alındı ve beş dakika dinlendikten sonra yeni pozisyon verildi. Pozisyon değişiminden sonraki 5. dakika PI, PVI, EscCO, SpO2 değerleri kayıt altına alındı.Bulgular: Katılımcıların farklı pozisyondayken ölçülen PI, PVI ile EscCO değerlerinde istatistiksel olarak anlamlı bir fark bulunamadı.Sonuç: Bu çalışma, PI, PVI ile EscCO nun tüm cerrahi pozisyonlarda herhangi bir değişikliğe uğramadığını ve her üç parametrenin de spontan solunumuna sahip genç sağlıklı bireylerde pozisyondan etkilenmediği ortaya koymuştur.

Differential activation of the human costal and crural diaphragm during voluntary and involuntary breaths.

The diaphragm is the primary muscle that generates the negative intrathoracic pressure to drive inspiratory airflow. The diaphragm consists of two parts, the costal and crural portions, with different roles during inspiration in animals, particularly when the stimulus to breathe is increased. In this study, the neural drive to the costal and crural portions of the diaphragm was assessed in nine healthy participants [8 male, aged 32 ± 13 yr (mean ± SD)]. Inspiratory electromyographic activity (EMG) was recorded from the costal diaphragm by using an intramuscular electrode and from the crural diaphragm with a multipair gastroesophageal catheter. Participants performed voluntary augmented breaths at 120%, 140%, and 160% of their tidal volume and also underwent progressive hypercapnia to induce involuntary breathing. Irrespective of the task, the increase in crural activity (normalized to quiet breathing) was only ~60% of the increase in costal activity (slope: 0.56 ± 0.30, P < 0.001). The onset and peak timing of EMG activity was similar for the costal and crural diaphragm during quiet breathing. Thus, when stimulated by either a voluntary or involuntary drive to breathe above tidal volume, the neural drive to the diaphragm was greater to the costal than to the crural portion.NEW & NOTEWORTHY Simultaneous electromyographic recordings from the human costal and crural diaphragm during voluntary augmented breathing and involuntary rebreathing show that the increase in inspiratory crural diaphragm activity was ~60% of the increase in costal diaphragm activity. However costal to crural diaphragm activation did not differ between the two tasks. The dissociation in the amplitude of activation of the costal and crural diaphragm becomes apparent only as the drive to breathe increases above tidal breathing.