Respiratory sinus arrhythmia versus neck/trapezius EMG and incentive inspirometry biofeedback for asthma: a pilot study

The Effect of Heart Rate Variability Biofeedback Training on Vagal Tone in Athletically Talented Secondary School Students

This study examines whether twelve sessions of heart rate variability biofeedback training would improve vagally mediated heart rate variability. If so, it would go some way in explaining why breathing-based interventions reduce clinical symptoms and improve non-clinical performance outcomes. Methods: Thirty participants (N = 30, Nfemale = 13) aged 14–13-year-old, all talented athletes, from a sport specialist school in SE London UK, were randomly divided into three groups, a control group, a psychology skills training combined with heart rate variability biofeedback training group, and a heart rate variability biofeedback only group. For the combined group, a variety of typical psychological skill training techniques were also used. Results: Paired participant t-test and the Wilcoxon Signed Rank test found non-significant differences between pre- and post-intervention measurements of heart rate variability. Non-significant results remained even after pooling the biofeedback training groups (n = 19). Conclusions: Our results do not indicate that beneficial effects associated with focused breathing training can be attributed to improved vagal tone. Further investigation into the underlying mechanisms of the benefits of focused breathing techniques is necessary to maximize clinical and non-clinical outcomes.

Reducing Test Anxiety by Device-Guided Breathing: A Pilot Study

Test anxiety remains a challenge for students and has considerable physiological and psychological impacts. The routine practice of slow, Device-Guided Breathing (DGB) is a major component of behavioral treatments for anxiety conditions. This paper addresses the effectiveness of using DGB as a self-treatment clinical tool for test anxiety reduction. This pilot study sample included 21 healthy men and women, all college students, between the ages of 20 and 30. Participants were randomly assigned to two groups: DGB practice (n = 10) and wait-list control (n = 11). At the beginning and the end of 3-weeks DGB training, participants underwent a stress test, followed by measures of blood pressure and reported anxiety. Anxiety reduction in the DGB group as compared to controls was not statistically significant, but showed a large effect size. Accordingly, the clinical outcomes suggested that daily practice of DGB may lead to reduced anxiety. We assume that such reduction may lead to improved test performance. Our results suggest an alternative treatment for test anxiety that may also be relevant for general anxiety, which is likely to increase due to the ongoing COVID-19 pandemic.

Process Design for Optimized Respiration Identification Based on Heart Rate Variability for Efficient Respiratory Sinus Arrhythmia Biofeedback

Respiratory sinus arrhythmia (RSA) is a phenomenon in which the heart rate (HR) changes with respiration, increasing during inspiration and decreasing during expiration. RSA biofeedback training has an effect in relieving negative mental conditions, such as anxiety and stress. Respiration is an important indicator affecting the parasympathetic activation within the body during RSA biofeedback training. Although there are existing studies that consider individual differences when selecting optimized respiration using heart rate variability, the studies that use the high frequency components of HRV, which is an indicator of parasympathetic activation, are insufficient. For this reason, this paper proposes a process to identify optimized respiration for efficient RSA feedback, consisting of three steps: (1) application, (2) optimization, and (3) validation. In the application phase, we measured PPG data against various respiratory cycles based on the HF components of HRV and calculated the proposed heart stabilization indicator (HSI) from the data. Then, we determined the optimized respiration cycle based on the HSI in the optimization step. Finally, we analyzed seven stress-related indices against the optimized respiration cycle. The experimental results show that HSI is associated with the parasympathetic nervous system activation, and the proposed method could help to determine the optimal respiratory cycle for each individual. Lastly, we expect that the proposed design could be used as an alternative to improving the efficiency of RSA biofeedback training.

Heart Rate Variability Biofeedback Improves Emotional and Physical Health and Performance: A Systematic Review and Meta Analysis

We performed a systematic and meta analytic review of heart rate variability biofeedback (HRVB) for various symptoms and human functioning. We analyzed all problems addressed by HRVB and all outcome measures in all studies, whether or not relevant to the studied population, among randomly controlled studies. Targets included various biological and psychological problems and issues with athletic, cognitive, and artistic performance. Our initial review yielded 1868 papers, from which 58 met inclusion criteria. A significant small to moderate effect size was found favoring HRVB, which does not differ from that of other effective treatments. With a small number of studies for each, HRVB has the largest effect sizes for anxiety, depression, anger and athletic/artistic performance and the smallest effect sizes on PTSD, sleep and quality of life. We found no significant differences for number of treatment sessions or weeks between pretest and post-test, whether the outcome measure was targeted to the population, or year of publication. Effect sizes are larger in comparison to inactive than active control conditions although significant for both. HRVB improves symptoms and functioning in many areas, both in the normal and pathological ranges. It appears useful as a complementary treatment. Further research is needed to confirm its efficacy for particular applications.

Not All Competitions Come to Harm! Competitive Biofeedback to Increase Respiratory Sinus Arrhythmia in Managers

Despite the positive impact on achievement, competition has been associated with elevated psychophysiological activation, potentially leading to a greater risk of cardiovascular diseases. Competitive biofeedback (BF) can be used to highlight the effects of competition on the same physiological responses that are going to be controlled through BF. However, it is still unknown whether competition could enhance the effects of respiratory sinus arrhythmia (RSA)-BF training in improving cardiac vagal control. The present study explored whether competitive RSA-BF could be more effective than non-competitive RSA-BF in increasing RSA in executive managers, who are at higher cardiovascular risk of being commonly exposed to highly competitive conditions. Thirty managers leading outstanding private or public companies were randomly assigned to either a Competition (n = 14) or a Control (n = 16) RSA-BF training lasting five weekly sessions. Managers in the Competition group underwent the RSA-BF in couples and each participant was requested to produce a better performance (i.e., higher RSA) than the paired challenger. After the training, results showed that managers in the Competition group succeeded in increasing cardiac vagal control, as supported by the specific increase in RSA (p < 0.001), the standard deviation of R-R wave intervals (SDNN; p < 0.001), and root mean square of the successive differences between adjacent heartbeats (rMSSD; p < 0.001). A significant increase in the percentage of successive normal sinus beat to beat intervals more than 50 ms (pNN50; p = 0.023; η2 p = 0.17), low frequency (p = ≤ 0.001; η2 p = 0.44), and high frequency power (p = 0.005; η2 p = 0.25) emerged independently from the competitive condition. Intriguingly, managers who compete showed the same reduction in resting heart rate (HR; p = 0.003, η2 p = 0.28), systolic blood pressure (SBP; p = 0.013, η2 p = 0.20), respiration rate (p < 0.001; η2 p = 0.46), and skin conductance level (SCL; p = 0.001, η2 p = 0.32) as non-competitive participants. Also, the same reduction in social anxiety (p = 0.005; η2 p = 0.25), state (p = 0.038, η2 p = 0.14) and trait anxiety (p = 0.001, η2 p = 0.31), and depressive symptoms (p = 0.023, η2 p = 0.17) emerged in the two groups. The present results showed that managers competing for increasing RSA showed a greater improvement in their parasympathetic modulation than non-competing managers. Most importantly, competition did not lead to the classic pattern of increased psychophysiological activation under competitive RSA-BF. Therefore, competition could facilitate the use of self-regulation strategies, especially in highly competitive individuals, to promote adaptive responses to psychological stress.

Cardiopulmonary Activity Monitoring Using Millimeter Wave Radars

Current cardiopulmonary activity monitoring is based on contact devices which cannot be used in extreme cases such as premature infants, burnt victims or rescue operations. In order to overcome these limitations, the use of radar technologies emerges as an alternative. This paper aims to enhance the comprehension that non-contact technologies, in particular radar techniques, offer as a monitoring tool. For this purpose, a modified low cost commercial 122 GHz frequency-modulated continuous-wave (FMCW) radar is used to better fit the current application domain. The radar signals obtained are processed using a classic linear filtering algorithm aiming to separate the breathing from the heartbeat component while preserving signals integrity. In a standoff configuration and with different subject orientations, results show that the signal obtained with the radar can be used to extract not only the respiratory and heartbeat rates, but also the heart rate variability (HRV) sequence. Moreover, results evidence the coupling between breathing and heartbeat, also showing that the HRV sequence obtained can identify the respiratory sinus arrhythmia (RSA) effect. Finally, the radar is tested in a simultaneous multi-target scenario, demonstrating its monitoring capabilities in more complex situations. Nevertheless, there are some challenges left to use the system in a real-life monitoring environments, such as the removal of random body movements.

An Anti-hyperventilation Instruction Decreases the Drop in End-tidal CO2 and Symptoms of Hyperventilation During Breathing at 0.1 Hz

Breathing at a frequency of around 0.1 Hz is widely used in basic research and in applied psychophysiology because it strongly increases fluctuations in the cardiovascular system and affects psychological functioning. Volitional control of breathing often leads to hyperventilation among untrained individuals, which may produce aversive symptoms and alter the psychological and physiological effects of the paced breathing. The present study investigated the effectiveness of a brief anti-hyperventilation instruction during paced breathing at a frequency of 0.1 Hz. Forty-six participants were randomly assigned to one of two groups: a group given an anti-hyperventilation instruction and a control group without such an instruction. The instruction asked participants to avoid excessively deep breathing and to breathe shallowly and naturally. Participants performed the breathing task for 10 min. Hyperventilation was measured by partial pressure of end-tidal CO₂ (PetCO₂); furthermore, symptoms of hyperventilation, feeling of air hunger, task difficulty, and affective state were measured by self-report. The results showed that paced breathing without instruction decreased PetCO₂ by 5.21 mmHg and that the use of the anti-hyperventilation instruction reduced the drop in PetCO₂ to 2.7 mmHg. Symptoms of hyperventilation were lower in the group with the anti-hyperventilation instruction. Neither the feeling of air hunger nor task difficulty were affected by the instruction. There were no significant effects of the instruction on affective state. The present study indicates that a brief anti-hyperventilation instruction may be used to decrease drop in PetCO₂ and symptoms of hyperventilation during breathing at 0.1 Hz and that the instruction is well tolerated.

Anxiety Disorders and Medical Comorbidity: Treatment Implications

Anxiety disorders are debilitating psychological disorders characterized by a wide range of cognitive and somatic symptoms. Anxiety sufferers have a higher lifetime prevalence of various medical problems. Chronic medical conditions furthermore increase the likelihood of psychiatric disorders and overall dysfunction. Lifetime rates of cardiovascular, respiratory, gastrointestinal, and other medical problems are disproportionately high in anxiety and panic/fear sufferers. The heightened comorbidity is not surprising as many symptoms of anxiety and panic/fear mimic symptoms of medical conditions. Panic disorder specifically is strongly linked to medical conditions due to its salient somatic symptoms, such as dyspnea, dizziness, numbness, chest pain, and heart palpitations, all of which can signal danger and deterioration for chronic disease sufferers. This chapter identifies shared correlates of medical illness and anxiety disorders and evidence for misinterpretation of symptoms as medically relevant and offers an analysis of implications for treatment of both types of conditions. We will concentrate on medical conditions with high associations for anxiety and panic by aspects of symptomatology, specifically neurological disorders (fibromyalgia, epilepsy, cerebral palsy), diabetes, gastrointestinal illness (irritable bowel syndrome, gastroesophageal reflux disease), and cardiovascular and respiratory illnesses (asthma).

Effects of Back Touching on Tidal Volume

The purpose of this basic experiment was to examine the effects of soft touching on an experiment participant’s back on tidal volume (TV), as an increase in TV was considered an indication of enhanced relaxation. Healthy experiment participants were divided into an intervention group, where soft touching was administered for two minutes on their back, and a control group, where they were asked to rest. Then the change in TV was measured using a spiro-meter two factor analysis of variance (ANOVA; mixture design) was conducted. As a result of two factor ANOVA, the intervention group’s TV changed with statistical significance, while no statistically significant change was observed in the control group. There was a possibility that soft touching on the back had a positive effect on the increase of TV and relaxation. As a result of soft touching on the back, TV was increased. Subjective indicators suggested that the relaxation was enhanced by soft touching on the back.

Protective effect of heart rate variability biofeedback on stress-induced lung function impairment in asthma

Psychological stress can provoke airway constriction in asthmatic patients, which may be because of autonomic nervous system dysfunction in asthma. We investigated the effect of enhancing respiratory sinus arrhythmia using heart rate variability biofeedback (HRV-BF) on spirometry performance and HRV indices during stress induced by Stroop Color-Word interference test in asthmatic patients and healthy volunteers. Stress caused decrease in FEV1%, FVC%, and PEF% compared to baseline in asthmatic patients, but not in healthy subjects. A single short duration episode of HRV-BF not only had a protective effect on stress-induced airway constriction, but also significantly augmented the level of FEV1% and FVC% as compared with their own baseline. Also, there was a significant correlation between HRV changes and the augmentation of spirometry performance in asthmatic patients receiving HRV-BF. Our findings indicated that even a single short duration episode of HRV-BF can decrease susceptibility to stress-induced lung function impairment in patients with asthma, which may be through the modulation of respiratory sinus arrhythmia.

Surface electromyography in inspiratory muscles in adults and elderly individuals: A systematic review

INTRODUCTION

Electromyography (EMG) helps to evaluate disorders and pulmonary behavior, as impairments in respiratory muscle function are associated with the development of diseases. There is a wide range of methods and protocols used to record and analyze EMG obtained from respiratory muscles, demonstrating a lack of standardization.

OBJECTIVE

To identify the most common procedures used to record surface EMG (sEMG) of inspiratory muscles in adults and elderly individuals through a systematic review (primary), and to evaluate the quality of the report presented by the studies (secondary).

METHOD

Studies published from January 1995 until June 2018 were searched for in the Web of Science, PubMed, LILACS, EBSCO and Embase databases. Only studies evaluating sEMG of inspiratory muscles were included.

RESULTS

The electronic search retrieved a total of 6697 titles and 92 of them were included. A great variability on the methods applied to both recording and processing/analyzing data was found. Therefore, the synthesis of practical/clinical evidence to support immediate recommendations was impaired. In general, the descriptions presented by the studies are poor.

CONCLUSION

The most common procedures used for sEMG were identified. Methodological studies with objective comparisons were fundamental for improving standardization, given the impossibility of recommendations from this review.

The effects of breathing at a frequency of 0.1 Hz on affective state, the cardiovascular system, and adequacy of ventilation

The present study aimed to investigate changes induced by breathing at 0.1 Hz in affective state, cardiovascular activity, and adequacy of ventilation as well as the relation between changes in peripheral physiological processes and alteration of affect. Eighty-three participants were randomly assigned to one of three groups: Two groups doing paced breathing at 0.1 Hz, one with and the other without a cover story hiding the goal of the experiment, and, as a control, paced breathing at 0.28 Hz. We measured the effects of breathing at 0.1 Hz on affective state (unpleasant and pleasant arousals), respiratory sinus arrhythmia (RSA), sympathetic control of the heart (preejection period, PEP), and adequacy of ventilation as measured by partial pressure of end-tidal CO₂ (PetCO₂ ). The use of a cover story did not influence the effects of paced breathing on the study outcomes. In the 0.1 Hz groups, unpleasant arousal decreased only among men. Changes in RSA were not related to changes in affect. Respiratory frequency did not influence PEP. However, changes in PEP were inversely related to changes in pleasant arousal. PetCO₂ decreased in all conditions, and a larger drop in PetCO₂ predicted a greater decrease in unpleasant arousal. The results obtained corroborate previous findings showing that slow paced breathing may lead to moderate hyperventilation among untrained participants and suggest that hyperventilation during breathing at 0.1 Hz is not deep enough to produce an increase in affective arousal.

Inhibiting the Physiological Stress Effects of a Sustained Attention Task on Shoulder Muscle Activity

Objective: The objective of this study was to investigate if a breathing technique could counteract the effects of hyperventilation due to a sustained attention task on shoulder muscle activity. Background: The trend towards higher levels of automation in industry is increasing. Consequently, manufacturing operators often monitor automated process for long periods of their work shift. Prolonged monitoring work requires sustained attention, which is a cognitive process that humans are typically poor at and find stressful. As sustained attention becomes an increasing requirement of manufacturing operators’ job content, the resulting stress experienced could contribute to the onset of many health problems, including work related musculoskeletal disorders (WRMSDs). Methods: The SART attention test was completed by a group of participants before and after a breathing intervention exercise. The effects of the abdominal breathing intervention on breathing rate, upper trapezius muscle activity and end-tidal CO₂ were evaluated. Results: The breathing intervention reduced the moderation effect of end-tidal CO₂ on upper trapezius muscle activity. Conclusions: Abdominal breathing could be a useful technique in reducing the effects of sustained attention work on muscular activity. Application: This research can be applied to highly-automated manufacturing industries, where prolonged monitoring of work is widespread and could, in its role as a stressor, be a potential contributor to WRMSDs.

Improving Managers' Psychophysical Well-Being: Effectiveness of Respiratory Sinus Arrhythmia Biofeedback

High work stress has been consistently associated with disturbed autonomic balance, specifically, lowered vagal cardiac control and increased sympathetic activity, which may lead to increased cardiovascular risk. Stress management procedures have been proposed to reduce autonomic dysfunctions related to work stress in different categories of workers exposed to heightened work demands, while a limited number of studies addressed this issue in managers. The present study was aimed at evaluating the effectiveness of a respiratory sinus arrhythmia (RSA) biofeedback (BF) intervention on psychological and physiological outcomes, in managers with high-level work responsibilities. Thirty-one managers leading outstanding private or public companies were randomly assigned to either a RSA-BF training (RSA-BF; N = 16) or a control group (N = 15). The RSA-BF training consisted of five weekly 45 min sessions, designed to increase RSA, whereas controls had to provide a daily stress diary once a week. After the training, managers in both groups reported reduced heart rate at rest, lower anxiety levels and improvement in health-related quality of life. More importantly, managers in the RSA-BF group showed increased vagal control (as indexed by increased RSA), decreased sympathetic arousal (as indexed by reduced skin conductance and systolic blood pressure) and lower emotional interferences, compared to managers in the control group. Results from this study showed that RSA-BF training was effective in improving cardiac autonomic balance at rest. Moreover, findings from this study underline the effectiveness of biofeedback in reducing psychophysiological negative outcomes associated with stress in managers.

A randomized-controlled trial of heart rate variability biofeedback for psychotic symptoms

Arousal and the way it is coped with are relevant to the emergence of psychotic symptoms. Heart rate variability (HRV) stems from autonomic responses to environmental demands such as stress and is an index of physiological arousal, adaptability, and homeostatic reflexes forming autonomic balance. A randomized-controlled between-subjects trial that compared HRV-biofeedback (BF) to an active relaxation and to a waiting control condition was conducted in a sample with attenuated subclinical psychotic symptoms (N = 84). A 20-min intervention was preceded and followed by repeated assessments of stress responses. Change scores of the post-stress periods were analyzed using ANOVAs for HRV, subjective stress, perceived control, and state paranoia. As expected, BF participants showed greater improvements in perceived control than waiting controls (p = 0.006). However, no group differences occurred in HRV, paranoid symptoms or subjective stress. In exploratory analyses in a subset of participants who were breathing per protocol, the expected effects were found for total HRV and state paranoia. Thus, this trial of HRV-BF for people with attenuated psychotic symptoms indicates that the intervention may hold potential if conducted per protocol. To reach this, longer training might be inevitable. Future studies are needed to further elucidate efficacy and applicability of HRV-BF in clinical samples.

Nonpharmacological interventions aimed at modifying health and behavioural outcomes for adults with asthma: a critical review

Evidence suggests that living with asthma is linked with psychological and behavioural factors including self-management and treatment adherence, and therefore, there is a reasonable hypothesis that nonpharmacological treatments may improve health outcomes in people living with this condition. A systematic review of randomized controlled trials (RCTs) of nonpharmacological interventions for adults with asthma was designed. Databases searched included The Cochrane Airways Group Register of trials, CENTRAL and Psychinfo. The literature search was conducted until May 2014. Twenty-three studies met the inclusion criteria and were organized into four groups: relaxation-based therapies (n = 9); mindfulness (n = 1), biofeedback techniques (n = 3); cognitive behavioural therapies (CBT) (n = 5); and multicomponent interventions (n = 5). A variety of outcome measures were used, even when trials belonged to the same grouping, which limited the ability to conduct meaningful meta-analyses. Deficiencies in the current evidence base, notably trial heterogeneity, means that application to clinical practice is limited and clear guidelines regarding the use of nonpharmacological therapies in asthma is limited. Relaxation and CBT, however, appear to have a consistent positive effect on asthma-related quality of life and some psychological outcomes, and lung function (relaxation only). Future trials should be informed by previous work to harmonize the interventions under study and outcome measures used to determine their effectiveness; only then will meaningful meta-analyses inform clinical practice.

Helping from the heart: Voluntary upregulation of heart rate variability predicts altruistic behavior

Our various daily activities continually require regulation of our internal state. These regulatory processes covary with changes in High Frequency Heart Rate Variability (HF-HRV), a marker of parasympathetic activity. Specifically, incidental increases in HF-HRV accompany positive social engagement behavior and prosocial action. Little is known about deliberate regulation of HF-HRV and the role of voluntary parasympathetic regulation in prosocial behavior. Here, we present a novel biofeedback task that measures the ability to deliberately increase HF-HRV. In two large samples, we find that a) participants are able to voluntarily upregulate HF-HRV, and b) variation in this ability predicts individual differences in altruistic prosocial behavior, but not non-altruistic forms of prosociality, assessed through 14 different measures. Our findings suggest that self-induction of parasympathetic states is involved in altruistic action. The biofeedback task may provide a measure of deliberate parasympathetic regulation, with implications for the study of attention, emotion, and social behavior.

Heart rate variability biofeedback in patients with alcohol dependence: a randomized controlled study

BACKGROUND AND OBJECTIVE

In patients with alcohol dependence, ethyl-toxic damage of vasomotor and cardiac autonomic nerve fibers leads to autonomic imbalance with neurovascular and cardiac dysfunction, the latter resulting in reduced heart rate variability (HRV). Autonomic imbalance is linked to increased craving and cardiovascular mortality. In this study, we sought to assess the effects of HRV biofeedback training on HRV, vasomotor function, craving, and anxiety.

METHODS

We conducted a randomized controlled study in 48 patients (14 females, ages 25-59 years) undergoing inpatient rehabilitation treatment. In the treatment group, patients (n=24) attended six sessions of HRV biofeedback over 2 weeks in addition to standard rehabilitative care, whereas, in the control group, subjects received standard care only. Psychometric testing for craving (Obsessive Compulsive Drinking Scale), anxiety (Symptom Checklist-90-Revised), HRV assessment using coefficient of variation of R-R intervals (CVNN) analysis, and vasomotor function assessment using laser Doppler flowmetry were performed at baseline, immediately after completion of treatment or control period, and 3 and 6 weeks afterward (follow-ups 1 and 2).

RESULTS

Psychometric testing showed decreased craving in the biofeedback group immediately postintervention (OCDS scores: 8.6±7.9 post-biofeedback versus 13.7±11.0 baseline [mean ± standard deviation], P<0.05), whereas craving was unchanged at this time point in the control group. Anxiety was reduced at follow-ups 1 and 2 post-biofeedback, but was unchanged in the control group (P<0.05). Following biofeedback, CVNN tended to be increased (10.3%±2.8% post-biofeedback, 10.1%±3.5% follow-up 1, 10.1%±2.9% follow-up 2 versus 9.7%±3.6% baseline; P=not significant). There was no such trend in the control group. Vasomotor function assessed using the mean duration to 50% vasoconstriction of cutaneous vessels after deep inspiration was improved following biofeedback immediately postintervention and was unchanged in the control group (P<0.05).

CONCLUSION

Our data indicate that HRV biofeedback might be useful to decrease anxiety, increase HRV, and improve vasomotor function in patients with alcohol dependence when complementing standard rehabilitative inpatient care.

The effect of a single session of short duration biofeedback-induced deep breathing on measures of heart rate variability during laboratory-induced cognitive stress: a pilot study

This study examines the acute effect of heart rate variability (HRV) biofeedback on HRV measures during and immediately after biofeedback and during the following laboratory-induced stress. Eighteen healthy males exposed to work-related stress were randomised into an HRV biofeedback group (BIO) or a comparative group (COM). Subjects completed a modified Stroop task before (Stroop 1) and after (Stroop 2) the intervention. Both groups had similar physiological responses to stress in Stroop 1. In Stroop 2, the COM group responded similarly to the way they did to Stroop 1: respiratory frequency (RF) and heart rate (HR) increased, RMSSD and high frequency (HF) power decreased or had a tendency to decrease, while low frequency (LF) power showed no change. The BIO group responded differently in Stroop 2: while RF increased and LF power decreased, HR, RMSSD and HF power showed no change. In the BIO group, RMSSD was higher in Stroop 2 compared to Stroop 1. In conclusion, HRV biofeedback induced a short term carry-over effect during both the following rest period and laboratory-induced stress suggesting maintained HF vagal modulation in the BIO group after the intervention, and maintained LF vagal modulation in the COM group.

How Does Heart Rate Variability Biofeedback Work? Resonance, the Baroreflex, and Other Mechanisms

Heart rate variability biofeedback is known to have multiple effects on the cardiovascular system, the respiratory system, and emotional reactivity. This paper reviews the origins of work on heart rate variability biofeedback, and mechanisms for its various effects, including direct effects on the baroreflex system and gas exchange efficiency, as well as indirect effects on emotional reactivity and possibly inflammatory activity. Resonance in the cardiovascular system is explained, as well as ways that heart rate variability biofeedback stimulates these resonance effects, through interactions between respiratory sinus arrhythmia and the baroreflex system. Relationships of these mechanisms to various clinical applications of heart rate variability biofeedback are explored, as are future extensions of biofeedback to the vascular tone baroreflex.

Systematic review of the effectiveness of breathing retraining in asthma management

In asthma management, complementary and alternative medicine is enjoying a growing popularity worldwide. This review synthesizes the literature on complementary and alternative medicine techniques that utilize breathing retraining as their primary component and compares evidence from controlled trials with before-and-after trials. Medline, PubMed, Cumulative Index to Nursing and Allied Health Literature and the Cochrane Library electronic databases were searched. Reference lists of all publications were manually checked to identify studies not found through electronic searching. The selection criteria were met by 41 articles. Most randomized controlled trials (RCTs) of the Buteyko breathing technique demonstrated a significant decrease in β(2)-agonist use while several found improvement in quality of life or decrease in inhaled corticosteroid use. Although few in number, RCTs of respiratory muscle training found a significant reduction in bronchodilator medication use. Where meta-analyses could be done, they provided evidence of benefit from yoga, Buteyko breathing technique and physiotherapist-led breathing training in improving asthma-related quality of life. However, considerable heterogeneity was noted in some RCTs of yoga. It is reasonable for clinicians to offer qualified support to patients with asthma undertaking these breathing retraining techniques.

Voluntarily produced increases in heart rate variability modulate autonomic effects of endotoxin induced systemic inflammation: an exploratory study

Exposure of healthy people to lipopolysaccharide (LPS; endotoxin) produces a pro-inflammatory response, subjective symptoms, and decreased heart rate variability (HRV). Given the efficacy of HRV biofeedback (BF) for treating asthma, the large autonomic effects of HRV BF, and the link between vagus nerve activity and inflammation, we hypothesized that HRV BF would dampen the acute manifestations of systemic inflammation induced by LPS challenge. Healthy participants age 18-40 were randomly assigned to four-one-hour training sessions of either HRV BF (n = 6) or a control 15/min paced breathing condition (n = 5) prior to acute experimentally induced LPS exposure. Participants were coached to do the procedures for 10 min each at five hourly time points after LPS injection, and then 2 h later. Subjective symptoms, HRV parameters, and plasma cytokine levels were measured at each time point, 2 h afterward, and the following morning. Participants were able to perform the procedures both during four pre-exposure training sessions and while experiencing LPS-induced symptoms. The HRV BF group showed significant attenuation of the LPS-induced decline in HRV for the 6 h following LPS exposure, suggesting that HRV BF decreased autonomic dysfunction produced by LPS-induced inflammation. HRV BF also reduced symptoms of headache and eye sensitivity to light, but did not affect LPS-induced levels of pro-inflammatory cytokines or symptoms of nausea, muscle aches, or feverishness. Further evaluation of HRV BF appears to be warranted among patients with inflammatory conditions.

A novel method for extracting respiration rate and relative tidal volume from infrared thermography

In psychophysiological research, measurement of respiration has been dependent on transducers having direct contact with the participant. The current study provides empirical data demonstrating that a noncontact technology, infrared video thermography, can accurately estimate breathing rate and relative tidal volume across a range of breathing patterns. Video tracking algorithms were applied to frame-by-frame thermal images of the face to extract time series of nostril temperature and to generate breath-by-breath measures of respiration rate and relative tidal volume. The thermal indices of respiration were contrasted with criterion measures collected with inductance plethysmography. The strong correlations observed between the technologies demonstrate the potential use of facial video thermography as a noncontact technology to monitor respiration.

Biofeedback of heart rate variability and related physiology: a critical review

Low heart rate variability (HRV) characterizes several medical and psychological diseases. HRV biofeedback is a newly developed approach that may have some use for treating the array of disorders in which HRV is relatively low. This review critically appraises evidence for the effectiveness of HRV and related biofeedback across 14 studies in improving (1) HRV and baroreflex outcomes and (2) clinical outcomes. Results revealed that HRV biofeedback consistently effectuates acute improvements during biofeedback practice, whereas the presence of short-term and long-term carry-over effects is less clear. Some evidence suggests HRV biofeedback may result in long-term carry-over effects on baroreflex gain, which is an area most promising for future investigations. On the other hand, concerning clinical outcomes, there is ample evidence attesting to efficacy of HRV biofeedback. However, because clinical and physiological outcomes do not improve concurrently in all cases, the mechanism by which HRV biofeedback results in salutary effects in unclear. Considerations for the field in addressing shortcomings of the reviewed studies and advancing understanding of the way in which HRV biofeedback may improve physiological and clinical outcomes are offered in light of the reviewed evidence.

Perspectives on complementary and alternative therapies in asthma

Asthma is a chronic disease that affects millions of individuals living in the USA. Proper asthma management is essential for controlling asthma symptoms and exacerbations. In recent years, however, there has been increased recognition of individuals using complementary and alternative medicine (CAM) to treat asthma. This article reviews the status of the current literature on various cultural factors that influence CAM use. In addition, current research of two widely used forms of CAM, herbal remedies and relaxation techniques, is presented. Future directions and recommendations to increase the methodological rigor of CAM research are discussed, particularly as they pertain to herbal remedies and relaxation strategies. The importance of well-designed research studies, including observational studies and randomized controlled trials, is highlighted.

Changes in pCO2, symptoms, and lung function of asthma patients during capnometry-assisted breathing training

In a recent pilot study with asthma patients we demonstrated beneficial outcomes of a breathing training using capnometry biofeedback and paced breathing assistance to increase pCO(2) levels and reduce hyperventilation. Here we explored the time course changes in pCO(2), respiration rate, symptoms and lung function across treatment weeks, in order to determine how long training needs to continue. We analyzed in eight asthma patients whether gains in pCO(2) and reductions in respiration rate achieved in home exercises with paced breathing tapes followed a linear trend across the 4-week treatment period. We also explored the extent to which gains at home were manifest in weekly training sessions in the clinic, in terms of improvement in symptoms and spirometric lung function. The increases in pCO(2) and respiration rate were linear across treatment weeks for home exercises. Similar increases were seen for in-session measurements, together with gradual decreases in symptoms from week to week. Basal lung function remained stable throughout treatment. With our current protocol of paced breathing and capnometry-assisted biofeedback at least 4 weeks are needed to achieve a normalization of pCO(2) levels and reduction in symptoms in asthma patients.

Resting respiratory sinus arrhythmia buffers against rejection sensitivity via emotion control

Emerging evidence suggests that high resting heart rate variability in the respiratory frequency band, or respiratory sinus arrhythmia (RSA) may capture individual differences in the capacity to engage in situationally appropriate regulation of affect and behavior. The authors therefore hypothesized that high RSA may act as a protective factor against difficulties controlling negative affect and hostile behaviors in conflicts with romantic partners in highly rejection-sensitive individuals--a population otherwise vulnerable to these responses. Results were consistent with this hypothesis such that highly rejection-sensitive participants reported less emotion control and more hostility in conflicts only if they were also low in RSA. Furthermore, emotion control mediated the joint effect of rejection-sensitivity and RSA on hostile conflict behavior. These results are consistent with the argument that resting RSA is a marker of flexible responding in the context of highly emotional situations, and further suggest that it may serve as a protective factor particularly in vulnerable populations.

Undertaking a systematic review: the road to successful completion

Abstract

The systematic review is an important research method that allows for the critical analysis of the results from a range of existing studies to answer research questions. The findings can be used to inform clinical decisions, as well as the development of protocols and guidelines. The aim of this paper is to explore the steps involved in undertaking a Cochrane systematic review and to encourage more nurses to participate in this world wide collaboration to answer questions that are relevant to nursing practice. The first stage of a review involves initiating a focussed clinical question in which the patient group or problem is identified as are the intervention, comparison and outcome, which will become the focus of study. Each review is guided by a protocol that is subject to peer review and followed by a structured search of the worldwide literature on the subject. Quality assessment and data extraction are done systematically and subject to cross-checking. The results are analysed using statistical methods, including meta-analysis. Publication is electronic in the Cochrane Library and many will also be published in other journals. As with all research, findings should be presented in a way that enables the reader to assess whether the review can be applied to their patient.

A Pilot Study of the Efficacy of Heart Rate Variability (HRV) Biofeedback in Patients with Fibromyalgia

Fibromyalgia (FM) is a non-inflammatory rheumatologic disorder characterized by musculoskeletal pain, fatigue, depression, cognitive dysfunction and sleep disturbance. Research suggests that autonomic dysfunction may account for some of the symptomatology of FM. An open label trial of biofeedback training was conducted to manipulate suboptimal heart rate variability (HRV), a key marker of autonomic dysfunction.

METHODS

Twelve women ages 18-60 with FM completed 10 weekly sessions of HRV biofeedback. They were taught to breathe at their resonant frequency (RF) and asked to practice twice daily. At sessions 1, 10 and 3-month follow-up, physiological and questionnaire data were collected.

RESULTS

There were clinically significant decreases in depression and pain and improvement in functioning from Session 1 to a 3-month follow-up. For depression, the improvement occurred by Session 10. HRV and blood pressure variability (BPV) increased during biofeedback tasks. HRV increased from Sessions 1-10, while BPV decreased from Session 1 to the 3 month follow-up.

CONCLUSIONS

These data suggest that HRV biofeedback may be a useful treatment for FM, perhaps mediated by autonomic changes. While HRV effects were immediate, blood pressure, baroreflex, and therapeutic effects were delayed. This is consistent with data on the relationship among stress, HPA axis activity, and brain function.

Characteristics of resonance in heart rate variability stimulated by biofeedback

As we previously reported, resonant frequency heart rate variability biofeedback increases baroreflex gain and peak expiratory flow in healthy individuals and has positive effects in treatment of asthma patients. Biofeedback readily produces large oscillations in heart rate, blood pressure, vascular tone, and pulse amplitude via paced breathing at the specific natural resonant frequency of the cardiovascular system for each individual. This paper describes how resonance properties of the cardiovascular system mediate the effects of heart rate variability biofeedback. There is evidence that resonant oscillations can train autonomic reflexes to provide therapeutic effect. The paper is based on studies described in previous papers. Here, we discuss the origin of the resonance phenomenon, describe our procedure for determining an individual's resonant frequency, and report data from 32 adult asthma patients and 24 healthy adult subjects, showing a negative relationship between resonant frequency and height, and a lower resonant frequency in men than women, but no relationship between resonant frequency and age, weight, or presence of asthma. Resonant frequency remains constant across 10 sessions of biofeedback training. It appears to be related to blood volume.

Psychological interventions for adults with asthma: a systematic review

AIM

The purpose of this study was to conduct a systematic review of randomized controlled trials where the efficacy of psychological interventions in modifying health and behavioural outcomes for adults with asthma was investigated.

METHOD

A review of randomized controlled trials was designed. The literature search was conducted until May 2005.

RESULTS

Fourteen studies, involving 617 adults, were included in the review. The use of 'as needed' medications was reduced by relaxation therapy (OR 4.47, CI 1.22-16.44), quality of life, measured using the Asthma Quality of Life Questionnaire, showed a positive effect following cognitive behavioural therapy (WMD 0.71, CI 0.23-1.19), and peak expiratory flow outcome data indicated a significant difference in favour of bio-feedback therapy (SMD 0.66, CI 0.09-1.23).

CONCLUSIONS

Some promising results did emerge from meta-analyses performed. However, due to heterogeneity and the low quality of included studies, this review was unable to draw firm conclusions for the role of psychological interventions in asthma. We recommend that larger and well-conducted randomized trials use valid outcome measures to evaluate the effectiveness of psychological interventions for adults with asthma.

Psychological interventions for adults with asthma

BACKGROUND

Many people have asthma, and for some their symptoms may be triggered by psychological factors. In addition compliance with medical therapy may have a psychological dimension. Therefore, psychological interventions aim to reduce the burden of symptoms and improve management of the disease.

OBJECTIVES

To assess the effectiveness of psychological interventions for adults with asthma.

SEARCH STRATEGY

The Cochrane Airways Group Specialised Register and PsycINFO were searched with pre-defined terms up until August 2005.

SELECTION CRITERIA

Randomised controlled trials published in any language assessing the effects of a psychological intervention compared with a form of control in adult participants were included in the review.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed the relevance of abstracts identified by electronic searching and retrieved agreed studies for further scrutiny. The studies that met the inclusion criteria were assembled and data extracted.

MAIN RESULTS

Fourteen studies, involving 617 particpants, were included in the review, however study quality was poor and sample sizes were frequently small. However, some pooled effects were analysed. The use of 'as needed' medications was reduced in two studies, (47 patients), by relaxation therapy (OR 4.47, CI 1.22 to 16.44). There was no significant difference in FEV1 for relaxation therapy in four studies of 150 patients, (SMD -0.01, CI -0.41 to 0.40). Quality of life, measured using the Asthma Quality of Life Questionnaire in two studies, (48 patients), showed a positive effect following CBT (WMD 0.71, CI 0.23 to 1.19). Peak Expiratory Flow outcome data in two studies, (51 patients), indicated a significant difference in favour of bio-feedback therapy (SMD 0.66, CI 0.09 to 1.23). The remainder of the findings between studies were conflicting. This may have been due to the different types of interventions used and the deficiencies in trial design.

AUTHORS' CONCLUSIONS

This review was unable to draw firm conclusions for the role of psychological interventions in asthma due to the absence of an adequate evidence base. Larger, well-conducted and reported randomised trials are required in this area, in order to determine the effects of these techniques in the treatment of asthma in adults.

Airflow and autonomic responses to stress and relaxation in asthma: the impact of stressor type

The impact of stress on respiratory airflow in asthmatics is unclear. Part of the uncertainty may spring from the different physiological effects of different stressors. Given their potential to elicit increases in parasympathetic vagal activity, stressful situations that present few opportunities for coping (passive coping stressors) may be particularly problematic for people with asthma. Thirty-one adult asthmatics participated in a protocol including a widely used passive coping stressor (the cold pressor test), an active coping stressor (mental arithmetic), an interview about an upsetting asthma-related incident (viewed as a potential passive coping stressor given the exposure to unpleasant memories), and progressive muscle relaxation. Repeated measurements of airflow (via peak expiratory flow), vagal tone (via heart rate variability), and other variables were obtained. The cold pressor test, asthma interview and progressive muscle relaxation produced significant decreases in airflow compared to the baseline period. The cold pressor test and progressive muscle relaxation produced significant, complementary increases in vagal tone. These results suggest that passive coping stressors and other stimuli (e.g., certain forms of relaxation) that elicit increased vagal tone may be associated with poorer asthma control, a view consistent with a significant negative correlation between the participant's mean vagal tone response to the tasks and score on a measure of asthma self-efficacy.

Biofeedback treatment for asthma

STUDY OBJECTIVES

We evaluated the effectiveness of heart rate variability (HRV) biofeedback as a complementary treatment for asthma.

PATIENTS

Ninety-four adult outpatient paid volunteers with asthma.

SETTING

The psychophysiology laboratory at The University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, and the private outpatient offices of participating asthma physicians.

INTERVENTIONS

The interventions were as follows: (1) a full protocol (ie, HRV biofeedback and abdominal breathing through pursed lips and prolonged exhalation); (2) HRV biofeedback alone; (3) placebo EEG biofeedback; and (4) a waiting list control.

DESIGN

Subjects were first prestabilized using controller medication and then were randomly assigned to experimental groups. Medication was titrated biweekly by blinded asthma specialists according to a protocol based on National Heart, Lung, and Blood Institute guidelines, according to symptoms, spirometry, and home peak flows.

MEASUREMENTS

Subjects recorded daily asthma symptoms and twice-daily peak expiratory flows. Spirometry was performed before and after each weekly treatment session under the HRV and placebo biofeedback conditions, and at triweekly assessment sessions under the waiting list condition. Oscillation resistance was measured approximately triweekly.

RESULTS

Compared with the two control groups, subjects in both of the two HRV biofeedback groups were prescribed less medication, with minimal differences between the two active treatments. Improvements averaged one full level of asthma severity. Measures from forced oscillation pneumography similarly showed improvement in pulmonary function. A placebo effect influenced an improvement in asthma symptoms, but not in pulmonary function. Groups did not differ in the occurrence of severe asthma flares.

CONCLUSIONS

The results suggest that HRV biofeedback may prove to be a useful adjunct to asthma treatment and may help to reduce dependence on steroid medications. Further evaluation of this method is warranted.

Behavioral interventions in asthma: biofeedback techniques

OBJECTIVES

Biofeedback techniques have long been recommended as an adjunctive treatment for bronchial asthma. Techniques that target lung function directly, or indirectly by altering facial muscle tension, heart rate, heart rate variability (HRV) or inspiratory volume together with accessory muscle tension, have been proposed. We review evidence for the effectiveness of these biofeedback interventions and discuss the psychophysiological rationale behind individual techniques.

METHOD

Controlled studies of biofeedback in asthma were retrieved using relevant search engines and reference lists of published articles. Effect sizes comparing intervention with control groups were calculated where appropriate.

RESULTS

Most of the studies suffer from methodological inadequacies or poor reporting of methods and results. Interventions targeting respiratory resistance directly have yielded only small and inconsistent changes in lung function and are difficult to implement without producing dynamic hyperinflation. Biofeedback-assisted facial muscle relaxation as an indirect intervention has yielded mixed results across studies, with only half of the studies showing significant albeit very small and clinically irrelevant improvements in lung function. The underlying physiological assumptions of the technique are questionable in the light of current knowledge of respiratory physiology. For other indirect techniques, only preliminary evidence of small effects is available.

CONCLUSION

Currently, there is little good evidence that biofeedback techniques can contribute substantially to the treatment of asthma.

Psychotherapeutic interventions for adults with asthma

BACKGROUND

Many people have asthma, and for some their symptoms may be triggered by psychological factors. In addition compliance with medical therapy may have a psychological dimension. Therefore, psychological interventions aim to reduce the burden of symptoms and improve management of the disease.

OBJECTIVES

To assess the effectiveness of psychological interventions for adults with asthma.

SEARCH STRATEGY

The Cochrane Airways Group specialised register and PsycINFO were searched with pre-defined terms until September 2003.

SELECTION CRITERIA

Randomised controlled trials published in any language assessing the effects of a psychological intervention compared with a form of control in adult participants were included in the review.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed the relevance of abstracts identified by electronic searching and retrieved agreed studies for further scrutiny. The studies that met the inclusion criteria were assembled and data extracted.

MAIN RESULTS

Twelve studies were included in the review, however study quality was poor and sample sizes were frequently small. No meta-analysis could be performed due to the diversity of interventions and the outcomes assessed. Findings between studies were conflicting. This may have been due to the different types of interventions used and the deficiencies in trial design.

REVIEWER'S CONCLUSIONS

This review was unable to draw firm conclusions for the role of psychological interventions in asthma due to the absence of an adequate evidence base. Large, well-conducted and reported randomised trials are required in this area, in order to determine the effects of these techniques in the treatment of asthma in adults.

Behavioral interventions in asthma. Breathing training

Breathing exercises are frequently recommended as an adjunctive treatment for asthma. A review of the current literature found little that is systematic documenting the benefits of these techniques in asthma patients. The physiological rationale of abdominal breathing in asthma is not clear, and adverse effects have been reported in chronic obstructive states. Theoretical analysis and empirical observations suggest positive effects of pursed-lip breathing and nasal breathing but clinical evidence is lacking. Modification of breathing patterns alone does not yield any significant benefit. There is limited evidence that inspiratory muscle training and hypoventilation training can help reduce medication consumption, in particular beta-adrenergic inhaler use. Breathing exercises do not seem to have any substantial effect on parameters of basal lung function. Additional research is needed on the psychological and physiological mechanisms of individual breathing techniques in asthma, differential effects in subgroups of asthma patients, and the generalization of training effects on daily life.

Heart rate variability biofeedback increases baroreflex gain and peak expiratory flow

OBJECTIVE

We evaluated heart rate variability biofeedback as a method for increasing vagal baroreflex gain and improving pulmonary function among 54 healthy adults.

METHODS

We compared 10 sessions of biofeedback training with an uninstructed control. Cognitive and physiological effects were measured in four of the sessions.

RESULTS

We found acute increases in low-frequency and total spectrum heart rate variability, and in vagal baroreflex gain, correlated with slow breathing during biofeedback periods. Increased baseline baroreflex gain also occurred across sessions in the biofeedback group, independent of respiratory changes, and peak expiratory flow increased in this group, independently of cardiovascular changes. Biofeedback was accompanied by fewer adverse relaxation side effects than the control condition.

CONCLUSIONS

Heart rate variability biofeedback had strong long-term influences on resting baroreflex gain and pulmonary function. It should be examined as a method for treating cardiovascular and pulmonary diseases. Also, this study demonstrates neuroplasticity of the baroreflex.

Psychological aspects of asthma

Asthma can be affected by stress, anxiety, sadness, and suggestion, as well as by environmental irritants or allergens, exercise, and infection. It also is associated with an elevated prevalence of anxiety and depressive disorders. Asthma and these psychological states and traits may mutually potentiate each other through direct psychophysiological mediation, nonadherence to medical regimen, exposure to asthma triggers, and inaccuracy of asthma symptom perception. Defensiveness is associated with inaccurate perception of airway resistance and stress-related bronchoconstriction. Asthma education programs that teach about the nature of the disease, medications, and trigger avoidance tend to reduce asthma morbidity. Other promising psychological interventions as adjuncts to medical treatment include training in symptom perception, stress management, hypnosis, yoga, and several biofeedback procedures.

Relaxation therapy in adult asthma. Is there new evidence for its effectiveness?

Studies of relaxation training for adult asthma patients were reviewed for the period between 1980 and 2000. Six controlled and three uncontrolled studies were identified, employing a variety of methods, such as progressive relaxation, functional relaxation, autogenic training, or yoga. Most studies had low sample sizes and suffered from one or more methodological deficiencies, such as suboptimal data analysis, high dropout rates, problematic measurement procedures, or insufficient descriptions of methodology and results. Overall effects on parameters of lung function, symptoms, medication consumption, and health care use were generally negligible. Problems with the underlying rationale of relaxation therapy in asthma are discussed from a psychophysiological viewpoint. Examples are given of potential beneficial and detrimental effects of these techniques on lung function with respect to emotional processes, the musculoskeletal system, and ventilation as targets of a relaxation intervention. It remains to be demonstrated that relaxation training can significantly contribute to the standard treatment of asthma in adult patients.

Zazen and cardiac variability

OBJECTIVE

This study examined the effects of "tanden breathing" by Zen practitioners on cardiac variability. Tanden breathing involves slow breathing into the lower abdomen.

METHODS

Eleven Zen practitioners, six Rinzai and five Soto, were each studied during 20 minutes of tanden breathing, preceded and followed by 5-minute periods of quiet sitting. During this time, we measured heart rate and respiration rate.

RESULTS

For most subjects, respiration rates fell to within the frequency range of 0.05 to 0.15 Hz during tanden breathing. Heart rate variability significantly increased within this low-frequency range but decreased in the high-frequency range (0.14-0.4 Hz), reflecting a shift of respiratory sinus arrhythmia from high-frequency to slower waves. Rinzai practitioners breathed at a slower rate and showed a higher amplitude of low-frequency heart rate waves than observed among Soto Zen participants. One Rinzai master breathed approximately once per minute and showed an increase in very-low-frequency waves (<0.05 Hz). Total amplitude of heart rate oscillations (across frequency spectra) also increased. More experienced Zen practitioners had frequent heart rhythm irregularities during and after the nadir of heart rate oscillations (ie, during inhalation).

CONCLUSIONS

These data are consistent with the theory that increased oscillation amplitude during slow breathing is caused by resonance between cardiac variability caused by respiration and that produced by physiological processes underlying slower rhythms. The rhythm irregularities during inhalation may be related to inhibition of vagal modulation during the cardioacceleratory phase. It is not known whether they reflect cardiopathology.