|Year : 2020 | Volume
| Issue : 9 | Page : 4833-4840
Effect of nurse-led home-based biofeedback intervention on the blood pressure levels among patients with hypertension: Pretest–posttest study
Sujitha Elavally1, Muralidharan Thoddi Ramamurthy2, Jeyagowri Subash3, Ramesh Meleveedu4, Munikumar Ramasamy Venkatasalu5
1 Department of Medical Surgical Nursing, Government College of Nursing, Thrissur, Kerala, India
2 Department of Cardiology, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, Tamil Nadu, India
3 Department of Paediatric Nursing, College of Nursing, East-Coast Institute of Medical Sciences, Puthucherry, India
4 Department of Accident and Emergency Medicine, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, Tamil Nadu, India
5 Department of Nursing, Oxford School of Nursing and Midwifery, Faculty of Health and Life Sciences, Oxford Brookes University, MR1/02,Marston Road Campus, Jack Straws Lane, Headington, Oxford, United Kingdom
|Date of Submission||21-Feb-2020|
|Date of Decision||13-Mar-2020|
|Date of Acceptance||19-May-2020|
|Date of Web Publication||30-Sep-2020|
Dr. Sujitha Elavally
Govt. College of Nursing, Thrissur - 680 596, Kerala
Source of Support: None, Conflict of Interest: None
Aim: To investigate the effect of nurse-led home-based biofeedback intervention on the blood pressure levels among patients with hypertension. Background: Nurse-led interventions are emerging as cost-effective as well as clinically proven in chronic illness management. Hypertension, a leading long-term cardiovascular condition, has autonomic dysregulation and increased sympathetic tone as its pathophysiological background. Complementary interventions evidenced to interplay hypertension pathophysiology. Design: A pretest–posttest design. Materials and Methods: Uncomplicated primary hypertension outpatients were randomly assigned as study group (n = 173) and control group (n = 173) at a tertiary care hospital. Sociodemographic, clinical, and outcome variables [the baseline blood pressure and galvanic skin response (GSR)] were collected. Study group patients were given four teaching sessions of abdominal breathing-assisted relaxation facilitated by GSR biofeedback. Daily home practice was encouraged and monitored to measure the effects on blood pressure and GSR at the end of the 1st, 2nd, and 3rd month of intervention. Results: The study group participants showed significant decrease in mean (SD) systolic [140.77 (8.31) to 136.93 (7.96), F = 469.08] and diastolic blood pressure [88.24 (5.42) to 85.77 (4.66), F = 208.21]. In contrast, control group participants had a mild increase in the mean systolic (F = 6.02) and diastolic blood pressure (F = 4.70) values from pretest to posttests. GSR showed a significant increase from 559.63 (226.33) to 615.03 (232.24), (F = 80.21) from pretest to posttest III. Conclusions: Use of home-based biofeedback-centered behavioral interventions enabled BP reduction among hypertensive patients. Further studies should use biochemical markers of sympathetic nervous system activity to endorse this home-based chronic illness intervention.
Keywords: Biofeedback, breathing relaxation, complementary therapy, hypertension, nurse-led interventions
|How to cite this article:|
Elavally S, Ramamurthy MT, Subash J, Meleveedu R, Venkatasalu MR. Effect of nurse-led home-based biofeedback intervention on the blood pressure levels among patients with hypertension: Pretest–posttest study. J Family Med Prim Care 2020;9:4833-40
|How to cite this URL:|
Elavally S, Ramamurthy MT, Subash J, Meleveedu R, Venkatasalu MR. Effect of nurse-led home-based biofeedback intervention on the blood pressure levels among patients with hypertension: Pretest–posttest study. J Family Med Prim Care [serial online] 2020 [cited 2020 Oct 27];9:4833-40. Available from: https://www.jfmpc.com/text.asp?2020/9/9/4833/296281
| Introduction|| |
Globally, around one billion people live with uncontrolled hypertension. Middle income countries report a prevalence rate of 40% for hypertension and despite pharmacological advances in management, it remains a common cause for premature mortality rates due to its cardio- and cerebro-vascular complications., There is a vast body of evidence which agrees that most non-pharmacological interventions are both clinically and economically effective in hypertension management,,, with less or no side effects. Systematic reviews reported that non-pharmacological mind–body interventions such as biofeedback, self-blood pressure monitoring, mindfulness, and yoga focused on neuro-psychological and behavioral components to reduce blood pressure and slow down the progress of hypertension.,,
Biofeedback is a self-regulation-based complementary therapy which helps patients acquire mental and emotional control over body processes. This is achieved through feeding back individuals with information on his/her own unconscious body functions and helping them to voluntarily control these functions and to decrease the activation of the autonomic nervous system. Biofeedback is also proved to have long-term useful effects in different ways for an array of diseases like Type 2 Diabetes mellitus, constipation, migraine headache, and chronic pain.,,
Evidence also suggests that breathing exercises are helpful in hypertension management when combined with biofeedback., Breathing relaxation stimulates parasympathetic nervous system activity via diaphragmatic stretch and consequent vagal stimulation, causing a fall in sympathetic parameters including heart rate, respiratory rate, and blood pressure, and a rise in Galvanic Skin Response. Thus, galvanic skin response (GSR), a sensitive indicator of sympathetic nervous system activity,, was selected for biofeedback.
Home-based interventions were proven to be successful in both cost terms and clinical effectiveness in many long-term conditions,, especially in the context of resource constrained countries. Patient empowerment models are suggested for effective Control of hypertension in such countries. This study aimed to measure the effectiveness of nurse-led, home-based biofeedback-assisted breathing relaxation therapy on blood pressure levels among patients with primary hypertension.
- To evaluate the effect of nurse-led home-based biofeedback intervention on blood pressure, GSR and dosage of antihypertensive medications among primary hypertensives
- To assess the compliance of breathing relaxation at home among the study group participants.
| Materials and Methods|| |
A randomized controlled study with pre- and posttest design was conducted among patients with primary (essential) hypertension in a tertiary university teaching hospital. Institutional Ethics Committee (IEC) and local department approvals were obtained before starting the data collection.
Setting and sample
A total of 666 patients with diagnoses of stage I uncomplicated primary hypertension in the age range 35–75 years attending the cardiology outpatient department of the selected setting were approached. Patients who were on the same antihypertensive regimen for at least 3 months at the point of selection were considered for inclusion. Those who were practicing any form of structured relaxation program or had serious visual disability were excluded. Also, those patients whose type of antihypertensive medications was changed during the study period for any reason were excluded from analysis. As the researcher simultaneously explored the level of anxiety among the same cohort in a different study, those on beta-blockers were excluded. A total of 346 patients who met the inclusion criteria were enrolled. This sample size was fixed to substantiate findings by applying a = 5% and power (1-β) = 80%, and 15% expected attrition.
Potential patients were screened for eligibility based on the inclusion criteria by verbal questions and perusing the clinical chart. The study protocol was explained to the eligible participants. Informed consent was sought from willing patients. 346 eligible outpatients who consented to participate were randomized using a random allocation sequence prepared by the statistician into study (n = 173) and control (n = 173) groups. Separate randomization sequence was followed for men and women to include them approximately equally in each arm. Allocation were and enrollment was carried out by the principal investigator. Recruitment followed CONSORT (Consolidated Standards of Reporting Trials 2010) guidelines [See [Figure 1].
To measure the effectiveness of the intervention, we used a demographic and clinical variables data sheet (gender, age, antihypertensive medications and dosage, height, weight, duration of the hypertension, dietary pattern, menopausal status of women, smoking and alcoholism habits, fasting blood sugar and serum cholesterol). In this study, blood pressure and GSR were collected as dependent variables.
Blood pressure readings were measured as per American Heart Association guidelines using a calibrated sphygmomanometer and graded according to the seventh report of the Joint National Commission on prevention, detection, and treatment of hypertension guidelines [Table 1]. The baseline GSR was gauged using a 250 mV impedance meter integrated biofeedback machine, which measured the skin resistance in kiloohms. The instrument was validated by the biomedical engineering department of the hospital. The intra-rater correlation coefficient of blood pressure measurements was high (.83). The number of practice days of relaxation at home was counted with the help of participants' self-markings in a simple home practice calendar issued to them. The dosage changes of antihypertensives were verified from the records.
Biofeedback-assisted home-based breathing relaxation intervention (BAHRI)
The BAHR intervention is a complementary therapy that included a simple abdominal breathing exercise practiced by patients at home following four teaching sessions of 30 min duration given 1 week apart at the hospital. The relaxation was facilitated by the GSR biofeedback machine. The intervention was given in a private room at a set temperature by a psychologist, assisted by the investigator. Participants were encouraged to deepen the relaxation consciously by using visual feedback. Relaxation became a learned response for each participant by the end of the teaching period. The relaxation was practiced at home for 20 min a day for 12 weeks and reinforcement was given at the end of each month. Posttest measurements of BP and GSR readings at the beginning of the reinforcement sessions were considered to appreciate the sustenance effect. All blood pressure readings were obtained between 11 am and 1 pm. The standard care, including nursing assessment, lab tests, physician consultation, follow-up advice, and medications were continued by both study and control group patients as before. Posttest measurements were carried out by a trained health professional who was blinded towards the random allotment. The number of home practice days and dosage changes were verified during every posttest session. Random telephonic reinforcement was employed to ensure compliance, with their consent.
Approval from the Institutional Ethics Committee (IEC –NI/10/AUG/18/27) was obtained. We maintained confidentiality of the data. All data were stored in a password-protected computer in a locked cupboard and the access to the data was limited to principal investigator and co-investigators.
The data were analyzed using SPSS version 17. Descriptive methods were used to summarize the characteristics of the participants and to describe the changes in the outcome parameters from the beginning to the end of the study. Since data followed a normal distribution, parametric analysis methods were selected. All significance was assessed at a level of P < 0.05. Chi-squared test was used to assess the baseline differences between the groups. Paired “t” tests analyzed differences within the groups for the consecutive measurements and for first–last measurements. Independent “t” tests were used to know the difference between the groups for any two measurements. Repeated measures ANOVA was employed to identify the intervention effect on blood pressure and GSR across the three posttests. Bonferroni correction was employed.
| Results|| |
A total of 666 outpatients were screened for eligibility. Of these, 346 were eligible and were assigned into either study or control groups (n = 173 each). The overall attrition was 13% (n = 45). Posttest analysis was done for 150 patients in the study group and 151 patients in the control group. The groups did not differ in their baseline characteristics [Table 2]. Reasons for sample loss included not willing to continue, busy domestic schedule, death (non-cardiac related), could not be located by the investigator, or migrated to a distant location. The type of antihypertensive medications was changed by the physician for 11 patients during the period of the study and were excluded from analysis.
Result 1: Effectiveness of biofeedback-assisted breathing relaxation intervention on overall blood pressure between study and control group
To measure the effectiveness of biofeedback-assisted breathing relaxation techniques, the number of patients who moved across the categories of blood pressure according to JNC-7 (2003) between the study and control group was analyzed [Table 3].
|Table 3: Effect of biofeedback assisted relaxation on category-wise distribution of participants|
Click here to view
During the pretest, all patients in both study and control groups belonged to the stage I category of blood pressure. During post-test III, the number of patients who moved from stage I to the pre-hypertension stage was 21 (14%) in the study group and five (3.3%) in the control group. Five (3.3%) in the control group got their blood pressure level accelerated to stage II. This category change was significant with a Chi-squared value of 20.06 at P < 0.001.
Result 2: Effectiveness of biofeedback-assisted breathing relaxation intervention on blood pressure among patients with different antihypertensive medications
We measured the effect of BAHRI on blood pressure with various antihypertensive medications. Participants who were taking a combination of diuretics and ACEI showed significant difference in mean systolic blood pressure between the study and control groups during posttest III with “t” values of -3.92 (P < 0.001). This was in contrast to participants who took diuretics, who showed maximum benefits of intervention on diastolic blood pressure only along with medications with “t” values of -3.71 (P < 0.001) [Table 4].
|Table 4: Comparison of effect of various antihypertensive medications on BP among the patients with stage I hypertension between study and control groups before and after intervention|
Click here to view
Result 3: Effectiveness of biofeedback-assisted breathing relaxation intervention on mean blood pressure from pretest to posttest III
As we compared the mean blood pressure values from pretest to posttests III among participants, there was a highly significant reduction in the systolic BP at P < 0.001(F = 469.68) in the study group, whereas in the control group, there was a significant raise from pretest to posttest III at P = 0.003 (F = 6.20). A similar pattern was observed for diastolic BP with a significant fall from pretest to posttest III among the study group with F = 208.21 (P < 0.001) and a significant rise for diastolic BP towards the end of the study with F = 4.70 (P = 0.008) [Table 5].
|Table 5: Repeated measures ANOVA of systolic and diastolic BP among patients with stage I hypertension in the study and the control groups before and after intervention|
Click here to view
Result 4: Effectiveness of biofeedback-assisted breathing relaxation intervention on mean blood pressure, dosage reductions and GSR
Mean blood pressure
During the pretest, there was no significant difference in the level of mean systolic blood pressure between the study and control groups. The 't' value was 0.17 (P = 0.866). During posttest I, the mean blood pressure values among the study and control groups did not show a significant difference. However, during posttest III, there were significant differences between the study and control group mean systolic blood pressure values, indicated by the “t” value of 4.13 (P < 0.001) [Table 6]. Similarly, during pretest, the mean diastolic blood pressure did not differ between the study and control groups, with “t” value of 0.95 (P = 0.066). However, there were significant differences between the study and control groups indicated by the “t” (P) value of 5.50 (0.001) during posttest III [Table 6].
We analyzed the effect of BAHRI on dosage reduction of antihypertensive medications among the study and control groups. At the end of the study, the total number of dosage reduction events was 19 (12.6%) among the study group participants. Six (3.9%) dosage reductions were reported in the control group. The difference in the number of dosage reductions of anti-hypertensive medications between the study and control group patients was significant at P < 0.05 with a Chi-squared value of 7.47 [Table 6].
The results indicated the effectiveness of biofeedback-assisted breathing relaxation technique on GSR over time. The difference in GSR in the study group participants between the pre and posttests was significant with an F value of 80.21 at level P < 0.001 [Table 6].
Result 5: Compliance of home relaxation practice among study group participants
The total number of days of home relaxation practice was 84 in the study group. On an average, the participants performed breathing relaxation on 91.7% of the days during intervention period. The mean (SD) monthly scores of study group accounted for an F (P) value of 0.950 (0.022), which was uniform between the intervention intervals [Table 6].
| Discussion|| |
We conducted a larger RCT to investigate the effectiveness of BAHRI on blood pressure among a population with stage I primary hypertension in a middle income country. Following a 3 month intervention, the study group participants were found to have statistically significant reductions in their blood pressure and dosage of antihypertensive medications. GSR increased from baseline values in the intervention group patients, signifying a fall in the sympathetic nervous system activity.
Structured relaxation therapies have resulted in parasympathetic dominance among patients with hypertension. Intervention studies,, reported significant reductions in both the SBP and DBP following a GSR biofeedback training program. To contribute to this literature, our larger sample RCT (N = 346) has proved similar effectiveness among patients with hypertension when home-based BAHRI was implemented. Poor medication compliance, which was not explored in the current study, may be the reason for a statistically significant (P = 0.003 & 0.008) increase in mean systolic and diastolic BP among the control group (in spite of professional routine care), so we strongly recommend to include the medication compliance factor in the future studies. Furthermore, similar to existing evidence, our study also evidenced that mean reduction in diastolic BP was less than that of systolic BP in the study group.
Current evidences reported less on the effectiveness of BAHRI on transferring patients from higher to lower level hypertension stages. In this study, we found that home-based BAHRI intervention resulted in a reduction from stage I to pre-hypertension. At the end of the study, 21 (14%) stage I hypertension participants had a reduced overall BP and moved to pre-hypertension. In contrast, five (3.3%) control group participants had their blood pressure level accelerated to stage II (P < 0.001). Further studies should explore the reasons for such transitions.
Our findings endorse that BAHRI increased GSR, which is an indicator of decreased sympathetic nervous system activity. Limited interventional studies reported similar decreasing GSR with BAHRI which is claimed to be induced by a reduced stress response. Future studies should investigate biomarkers to support the current evidence of GSR increase.
A study by using a 16-week complementary intervention including diaphragmatic breathing proved to reduce the dosage of diuretics in 70.4% of hypertensive participants in the intervention group. In our study, the lower percentage of dosage reductions (12.6%) in the study group may be attributed to the shorter follow-up period, that is, 3 months' duration. In particular, BAHRI produced significant BP reduction among patients on ACE inhibitors in the study group compared with the control group. Indeed, the ASCOT-BPLA hypertension trial has already proved the extended cardiovascular benefits of ACE inhibitors other than BP reductions. Such positive results might be due to the fact that daily compliance rates of relaxation at home was maintained between 84 and 90%.
Finally, our study found that home-based relaxation practice results in significant reduction in systolic and diastolic blood pressure, hence we conclude the practice to be effective and suitable as an out-of-hospital intervention. The telephonic reminders were incorporated to monitor patient practice and involvement in the present study based on the fact that boosting the adherence to the therapeutic measures optimize BP control. Significance of this part of the intervention is endorsed by the results of a systematic review, which reported improved health outcomes among patients with heart failure following remote monitoring using tele-monitor, mobile phone, and video conference. Similarly, in another experimental study, the feasibility, acceptance, and effectiveness of digital tools in improving hypertension control and lifestyle change was testified. Future research should explore nurse-led community-based models to validate our findings.
The scope of our findings was limited by the following factors: the shorter duration of the study; patients with poor medication compliance behavior influencing the study outcomes; and the affluent nature of patients from urban settings.
| Conclusion|| |
The study concludes that a home-based complementary intervention, biofeedback-based relaxation therapy, along with medications, reduces blood pressure among patients with hypertension. We also found that GSR is a useful indicator to measure the sympathetic output for behavioral intervention. Further studies should use biomarkers of sympathetic nervous system activity to endorse the use of this biofeedback-assisted relaxation.
Relevance to clinical practice and primary care
This paper proves that biofeedback combined with breathing exercise could cause a statistically significant drop in the blood pressure levels. When used among at-risk population, such home-based relaxation techniques can delay the onset of hypertension and defer the point of initiation of drug therapy. Nurse-led interventions can be successfully incorporated in to the public health care system to control chronic illnesses. Outpatient clinical management of hypertension can consider such initiatives to enhance treatment effectiveness.
Summary of the paper
Home-based non-pharmacological intervention is proven as feasible and clinically effective in reducing systolic and diastolic blood pressure among patients with primary hypertension. The current home-based breathing relaxation interventions is also proven as operational in reducing the SNS activity among patients with high blood pressure as indicated by the change in the GSR among the intervention group of patients.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
World Health Organisation. Description of the global burden of NCDs, their risk factors and determinants. World Health Organization; 2011.
Joshi SR, Saboo B, Vadivale M, Dani SI, Mithal A, Kaul U, et al
. Prevalence of diagnosed and undiagnosed diabetes and hypertension in India—results from the Screening India's Twin Epidemic (SITE) study. Diabetes Technol Ther 2012;14:8-15.
Dickinson H, Campbell F, Beyer F, Nicolson D, Cook J, Ford G, et al
. Relaxation therapies for the management of primary hypertension in adults: A Cochrane review. J Hum Hypertens 2008;22:809-20.
Osamor PE, Owumi BE. Complementary and alternative medicine in the management of hypertension in an urban Nigerian community. BMC Complement Altern Med 2010;10:36.
Yeh GY, Wang C, Wayne PM, Phillips R. Tai chi exercise for patients with cardiovascular conditions and risk factors: A systematic review. J Cardiopulm Rehabil Prev 2009;29:152-60.
Nahas R. Complementary and alternative medicine approaches to blood pressure reduction An evidence-based review. Can Fam Physician 2008;54:1529-33.
Anderson JG, Taylor AG. Use of complementary therapies by individuals with or at risk for cardiovascular disease: Results of the 2007 national health interview survey. J Cardiovasc Nurs 2012;27:96.
Oza DN, Patel TA, Verma RJ. Role of yogic practices in individuals with hypertension and low-peak expiratory flow rate (PEFR) of Ahmedabad city. Indian Journal of Traditional Knowledge 2019;18:589-94.
Moss D. The use of general biofeedback in the pursuit of optimal performance. Case studies in applied psychophysiology: Neurofeedback and biofeedback treatments for advances in human performance. 2012. p. 1-16.
Carolyn Y, Montgomery D. Evidence-Based Practice in Biofeedback and Neurofeedback: AAPB Wheat Ridge, CO; 2008.
Moravec CS. Biofeedback therapy in cardiovascular disease: Rationale and research overview. Cleve Clin J Med 2008;75:S35-8.
Ebrahem SM, Masry SE. Effect of relaxation therapy on depression, anxiety, stress and quality of life among diabetic patients. Clin Nurs Stud 2017;5:35.
Rao SS, Valestin J, Brown CK, Zimmerman B, Schulze K. Long-term efficacy of biofeedback therapy for dyssynergic defecation: Randomized controlled trial. Am J Gastroenterol 2010;105:890-6.
Haines T, Bowles K-A. Cost-effectiveness of using a motion-sensor biofeedback treatment approach for the management of sub-acute or chronic low back pain: Economic evaluation alongside a randomised trial. BMC Musculoskeletal Disord 2017;18:18.
Simón MA, Bueno AM. Efficacy of biofeedback therapy in the treatment of dyssynergic defecation in community-dwelling elderly women. J Clin Gastroenterol 2017;51:e90-4.
Wang S-Z, Li S, Xu X-Y, Lin G-P, Shao L, Zhao Y, et al
. Effect of slow abdominal breathing combined with biofeedback on blood pressure and heart rate variability in prehypertension. J Altern Complement Med 2010;16:1039-45.
Kulur AB, Haleagrahara N, Adhikary P, Jeganathan P. Effect of diaphragmatic breathing on heart rate variability in ischemic heart disease with diabetes. Arq Bras Cardiol 2009;92:457-63.
Busch V, Magerl W, Kern U, Haas J, Hajak G, Eichhammer P. The effect of deep and slow breathing on pain perception, autonomic activity, and mood processing—An experimental study. Pain Med 2012;13:215-28.
Upadhyay Dhungel K, Malhotra V, Sarkar D, Prajapati R. Effect of alternate nostril breathing exercise on cardiorespiratory functions. Nepal Med Coll J 2008;10:25-7.
Lin G, Xiang Q, Fu X, Wang S, Wang S, Chen S, et al
. Heart rate variability biofeedback decreases blood pressure in prehypertensive subjects by improving autonomic function and baroreflex. J Altern Complement Med 2012;18:143-52.
Nagai Y, Goldstein LH, Critchley HD, Fenwick PBC. Influence of sympathetic autonomic arousal on cortical arousal: Implications for a therapeutic behavioural intervention in epilepsy. Epilepsy Res 2004;58:185-93.
Zwisler A-D, Norton RJ, Dean SG, Dalal H, Tang LH, Wingham J, et al
. Home-based cardiac rehabilitation for people with heart failure: A systematic review and meta-analysis. Int J Cardiol 2016;221:963-9.
Dixon P, Hollinghurst S, Edwards L, Thomas C, Foster A, Davies B, et al
. Cost-effectiveness of telehealth for patients with depression: Evidence from the healthlines randomised controlled trial. Br J Psychiatry Open 2016;2:262-9.
Patel P, Ordunez P, DiPette D, Escobar MC, Hassell T, Wyss F, et al
. Improved blood pressure control to reduce cardiovascular disease morbidity and mortality: The standardized hypertension treatment and prevention project. J Clin Hypertens 2016;18:1284-94.
Smith L. Practice guidelines. New AHA recommendations for blood pressure measurement. Am Fain Physician 2005;72:1391-8.
Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, et al
. The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: The JNC 7 report. JAMA 2003;289:2560-71.
Thanalakshmi J, Maheshkumar K, Kannan R, Sundareswaran L, Venugopal V, Poonguzhali S. Effect of Sheetali pranayama on cardiac autonomic function among patients with primary hypertension-A randomized controlled trial. Complement Ther Clin Pract 2020;39:101138.
Khanna A, Paul M, Sandhu JS. A study to compare the effectiveness of GSR biofeedback training and progressive muscle relaxation training in reducing blood pressure and respiratory rate among highly stressed individuals. Indian J Physiol Pharmacol 2007;51:296.
Tsai P-S, Chang N-C, Chang W-Y, Lee P-H, Wang M-Y. Blood pressure biofeedback exerts intermediate-term effects on blood pressure and pressure reactivity in individuals with mild hypertension: A randomized controlled study. J Altern Complement Med 2007;13:547-54.
Yucha CB, Tsai P-S, Calderon KS, Tian L. Biofeedback-assisted relaxation training for essential hypertension: Who is most likely to benefit? J Cardiovasc Nurs 2005;20:198-205.
Ziv A, Vogel O, Keret D, Pintov S, Bodenstein E, Wolkomir K, et al
. Comprehensive approach to lower blood pressure (CALM-BP): A randomized controlled trial of a multifactorial lifestyle intervention. J Hum Hypertens 2013;27:594-600.
Flack JM, Atlas SA, Pool JL, White WB. Renin-angiotensin aldosterone system and hypertension: Current approaches and future directions. J Manag Care Pharm 2007;13(Suppl B):1-39.
Carey RM, Muntner P, Bosworth HB, Whelton PK. Prevention and control of hypertension: JACC Health Promotion Series. Vol. 72, Journal of the American College of Cardiology. Elsevier USA; 2018. p. 1278-93.
Bashi N, Karunanithi M, Fatehi F, Ding H, Walters D. Remote monitoring of patients with heart failure: An overview of systematic reviews. J Med Internet Res 2017;19:e18.
Milani RV, Lavie CJ, Bober RM, Milani AR, Ventura HO. Improving hypertension control and patient engagement using digital tools. Am J Med 2017;130:14-20.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]