Biofeedback treatment of prehypertension: analyses of efficacy, heart rate variability and EEG approximate entropy

Building Resilience in an Urban Police Department

OBJECTIVE

The aim of this study is to examine a resilience training intervention that impacts autonomic responses to stress and improves cardiovascular risk, psychological, and physiological outcomes in police.

METHODS

Officers [(n = 38) 22 to 54 years] modified emotional and physical responses to stress using self-regulation. Measurements include psychological and physiological measures [eg, heart rate variability (HRV), blood pressure, C-reactive protein)] obtained at three time intervals.

RESULTS

Age was significantly (P < 0.05) associated with changes on several measures of psychological stress (eg, critical incident stress, emotional vitality, and depression). Associations were found between coherence and improved HbA1c (r = -0.66, P < 0.001) and stress due to organizational pressures (r = -0.44, P = 0.03). Improvements in sympathetic and parasympathetic contributors of HRV were significant (P < 0.03).

CONCLUSION

A stress-resilience intervention improves certain responses to job stress with greater benefits for younger participants.

Testing a Resilience Training Program in Police Recruits: A Pilot Study

Background:

Stress from multiple sources is inherent in law enforcement. However, it is possible to modify responses to stress with resilience training that includes teaching techniques to modify emotional and physical responses to stress, interface with mental health professionals, and practice sessions to improve self-regulation of responses to stress including coherence, a measure of heart rate variability. A gap exists in the research, however, regarding evaluation of the duration of effects after the initial resilience training.

Method:

Subjects included ( N = 34) recruits enrolled in summer 2015 at the Milwaukee Police Academy. An experimental design was used to compare recruits who received resilience training to recruits in the control group.

Results:

No statistically significant differences between the groups were found for self-reported measures of stress and resilience. For the treatment group ( n = 17), change in coherence was significant ( p < .001) and improvement in the Personal Organizational Quality Assessment Emotional Buoyancy subscale correlated significantly with the number of practice sessions ( r = .63, p = .01) and marginally with change in coherence ( r = .47, p = .07).

Conclusion:

Results confirm several significant effects of resilience training with recruits.

Electrocardiography-Derived Predictors for Therapeutic Response to Treatment in Children with Postural Tachycardia Syndrome

OBJECTIVE

To explore whether electrocardiography (ECG) variables could be used to predict responses to physical treatment in children with postural tachycardia syndrome (POTS).

STUDY DESIGN

Forty children with POTS and 32 healthy controls were enrolled in this study. General information and hemodynamic and supine ECG variables, including QT interval dispersion (QTd), were collected. The children with POTS received physical treatment and 3 months of follow-up. A receiver-operating characteristic curve was used to evaluate the value of ECG variables for predicting the effectiveness of physical treatment.

RESULTS

Compared with the healthy children, the children with POTS had longer baseline QTd and heart rate (HR)-corrected QTd (QTcd), but shorter minimum QT intervals (QTmin) and minimum HR-corrected QT intervals (P < .05). In children with POTS, responders to physical treatment had a longer baseline time between QRS complexes (RR) interval of minimum QT interval and a longer QTcd compared with nonresponders. A longer QTcd was a significant risk factor for the presence of POTS (OR, 1.022; P = .02) and for undesirable responses to physical treatment in children with POTS (OR, 1.044; P = .03). Baseline QTcd was positively correlated with the HR elevation from supine to upright seen in children with POTS (r = 0.348; P = .003). Receiver operating characteristic curve analysis demonstrated an area under the curve of 0.73, and using 43.0 msec as a cutoff of QTcd yielded a sensitivity of 90% and a specificity of 60%.

CONCLUSION

QTcd might be useful for predicting the effectiveness of physical treatment for POTS in children.

Involvement of MAPK/NF-κB signaling in the activation of the cholinergic anti-inflammatory pathway in experimental colitis by chronic vagus nerve stimulation

BACKGROUND

Autonomic nervous system dysfunction is implicated in the etiopathogenesis of inflammatory bowel diseases (IBD). Therapies that increase cardiovagal activity, such as Mind-Body interventions, are currently confirmed to be effective in clinical trials in IBD. However, a poor understanding of pathophysiological mechanisms limits the popularization of therapies in clinical practice. The aim of the present study was to explore the mechanisms of these therapies against 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats using a chronic vagus nerve stimulation model in vivo, as well as the lipopolysaccharide (LPS)-induced inflammatory response in human epithelial colorectal adenocarcinoma cells (Caco-2) by acetylcholine in vitro.

METHODS AND RESULTS

Colitis was induced in rats with rectal instillation of TNBS, and the effect of chronic VNS (0.25 mA, 20 Hz, 500 ms) on colonic inflammation was evaluated. Inflammatory responses were assessed by disease activity index (DAI), histological scores, myeloperoxidase (MPO) activity, inducible nitric oxide synthase (iNOS), TNF-α and IL-6 production. The expression of Mitogen-activated protein kinases (MAPK) family members, IκB-α, and nuclear NF-κB p65 were studied by immunoblotting. Heart rate variability (HRV) analysis was also applied to assess the sympathetic-vagal balance. DAI, histological scores, MPO activity, iNOS, TNF-α and IL-6 levels were significantly decreased by chronic VNS. Moreover, both VNS and acetylcholine reduced the phosphorylation of MAPKs and prevented the nuclear translocation of NF-κB p65. Methyllycaconitine (MLA) only reversed the inhibitory effect on p-ERK and intranuclear NF-κB p65 expression by ACh in vitro, no significant change was observed in the expression of p-p38 MAPK or p-JNK by MLA.

CONCLUSION

Vagal activity modification contributes to the beneficial effects of the cholinergic anti-inflammatory pathway in IBD-related inflamed colonic mucosa based on the activation of MAPKs and nuclear translocation of NF-κB. Our work may provide key pathophysiological mechanistic evidence for novel therapeutic strategies that increase the cardiovagal activity in IBD patients.

Heart rate variability biofeedback decreases blood pressure in prehypertensive subjects by improving autonomic function and baroreflex

BACKGROUND

Individuals with prehypertension are at risk of hypertension and cardiovascular diseases, and yet efficient interventions are lagging behind. Studies indicate that heart rate variability-biofeedback (HRV-BF) increases HRV and baroreflex sensitivity (BRS) as well as reduces related pathological symptoms, suggesting potentially beneficial effects of HRV-BF on prehypertension, but little is known about these effects. In this study, these effects were investigated and their mechanisms were explored.

OBJECTIVES

The effect of HRV-BF on prehypertension in young adults and its potential mechanism were explored.

DESIGN

Forty-three (43) individuals with prehypertension were recruited and classified into three categories: HRV-BF group, slow abdominal breathing group, and control group. All groups were assessed with measurements of noninvasive blood pressure (BP), BRS, respiration, and galvanic skin response (GSR) at pre-intervention, in the entire process of each session, at postintervention, as well as at a 3-month follow-up.

INTERVENTIONS

Subjects participated in a 10-session HRV-BF protocol or simple slow abdominal breathing protocol conducted over 5 weeks. A 3-month follow-up was also performed on these individuals.

RESULTS

The incidence of prehypertension was as high as 14.5% in young college students. Individuals with prehypertension were lower in BRS (7.5±5.2 ms/mm Hg) and HRV (log10-transformed of the standard deviation of normal-to-normal beats [SDNN]=1.62±0.13 ms, lgTotal power of spectral density in the range of frequencies between 0 and 0.4Hz (TP)=8.02±0.55 ms2) than those with normal blood pressure (BRS=18.4±7.4 ms/mm Hg, lgSDNN=1.79±0.10 ms, lgTP=8.68±0.85 ms2). HRV-BF reduced blood pressure (from 131.7±8.7/79.3±4.7 mm Hg to 118.9±7.3 mm Hg/71.9±4.9 mm Hg, p<0.01), increased BRS (from 7.0±5.9 ms/mm Hg to 15.8±5.3 ms/mm Hg, p<0.01) and increased HRV (lgSDNN from 1.61±0.11 to 1.75±0.05 ms, and lgTP from 8.07±0.54 to 9.08±0.41 ms2, p<0.01). These effects were more obvious than those of the slow-breathing group, and remained for at least 3 months. HRV-BF also significantly increased vagus-associated HRV indices and decreased GSR (indices of sympathetic tone).

CONCLUSIONS

These effects suggest that HRV-BF, a novel behavioral neurocardiac intervention, could enhance BRS, improve the cardiac autonomic tone, and facilitate BP adjustment for individuals with prehypertension.

Effect of slow abdominal breathing combined with biofeedback on blood pressure and heart rate variability in prehypertension

OBJECTIVE

Prehypertension is a new category designated by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7) in 2003. Managing prehypertension with nonpharmacological intervention is possibly beneficial to the prevention of hypertension. In this study, we observed the effect of slow abdominal breathing combined with electromyographic (EMG) biofeedback training on blood pressure (BP) in prehypertensives and assessed the changes of heart rate variability (HRV) in order to find an optional intervention to prevent hypertension and acquire some experimental data to clarify the underlying neural mechanism.

METHODS

Twenty-two (22) postmenopausal women with prehypertension were randomly assigned to either the experiment group or the control group. The experiment group performed 10 sessions of slow abdominal breathing (six cycles/min) combined with frontal electromyographic (EMG) biofeedback training and daily home practice, while the control group only performed slow abdominal breathing and daily home practice. BP and HRV (including R-R interval and standard deviation of the normal-normal intervals [SDNN]) were measured.

RESULTS

Participants with prehypertension could lower their systolic blood pressure (SBP) 8.4 mm Hg (p < 0.001) and diastolic blood pressure (DBP) 3.9 mm Hg (p < 0.05) using slow abdominal breathing combined with EMG biofeedback. The slow abdominal breathing also significantly decreased the SBP 4.3 mm Hg (p < 0.05), while it had no effect on the DBP (p > 0.05). Repeated-measures analyses showed that the biofeedback group + abdominal respiratory group (AB+BF) training was more effective in lowering the BP than the slow breathing (p < 0.05). Compared with the control group, the R-R interval increased significantly during the training in the AB+BF group (p < 0.05). The SDNN increased remarkably in both groups during the training (p < 0.05).

CONCLUSIONS

Slow abdominal breathing combined with EMG biofeedback is an effective intervention to manage prehypertension. The possible mechanism is that slow abdominal breathing combined with EMG biofeedback could reduce sympathetic activity and meanwhile could enhance vagal activity.

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.