Biofeedback therapeutic effects on blood pressure levels in hypertensive individuals: A systematic review and meta-analysis.

INTRODUCTION: Systemic arterial hypertension (SAH) is considered a multifactorial disease characterized by a persistent increase in blood pressure levels. Currently, the efficient control of blood pressure is achieved by both the use of pharmacological therapy and the control of risk factors. In addition, the use of biofeedback (BFB) as a non-pharmacological strategy represents a promising therapy. OBJECTIVE: This study aims to evaluate the effects of BFB on systolic and diastolic blood pressure levels, as well as on environmental and psychosocial factors in patients with essential SAH. METHODS: A systematic review (SR) of the literature was carried out in English and Portuguese using the following databases: SCIELO, LILACS, CINAHL, Cochrane, and PubMed. The search strategy included a mix of terms for the key concepts Biofeedback, Heart Rate Variability, Psychophysiological Feedback, and Heart Biofeedback. Studies were analyzed independently. RESULTS: The included studies evaluated a total of 462 subjects of both sexes. The meta-analysis revealed that BFB significantly elicited greater blood pressure control, mainly improving DBP levels (Z = 2.15; P = 0.03). DISCUSSION: Besides improvement in DBP readings post-intervention, BFB also resulted in better disease-related environmental and psychosocial factors, such as reduced stress levels. The magnitude of effect did not appear to depend on the type of BFB applied. CONCLUSION: This SR demonstrated that BFB with visual and/or auditory information is a complementary option to pharmacological treatment in the management of individuals with systolic and diastolic arterial hypertension. Moreover, the use of this adjuvant therapy seems to facilitate better DPB control.

Impaired heart rate variability, Valsalva and 30:15 ratio indexes are associated with reduced submaximal exercise capacity in subjects with diabetes mellitus.

AIMS: To assess cardiac autonomic control and its association with submaximal exercise measured using the 6-minute walk test (6MWT) in subjects with type-2 diabetes mellitus (DM2). METHODS: Cardiac autonomic control was assessed using Ewing's tests and heart rate variability (HRV) in DM2 volunteers (DG, n = 22) and sex-, age- and body mass index-matched non-diabetic controls (CG, n = 22) before, during and after 6MWT. RESULTS: Before the 6MWT, DG presented lower HRV represented by reduced SDNN [median 28.9 ms2 (IQR:18.6-35.4) vs. 45.1 (IQR:39.2-62.67), p < 0.001] and Total Power [median 785 ms2 (IQR:256-1264) vs. 1757 ms2 (IQR:1006-2912), p = 0.004]. Exercise capacity was reduced in DG [maximal predicted distance (%) = 88.4 ±â€¯6.4 vs. 95.2 ±â€¯11.0%, p = 0.018]. DG demonstrated lower global HRV during recovery and lower parasympathetic drive, represented by reduced RMSSD, during all phases of the 6MWT. Moreover, supine HR (r = -0.32), HR orthostatism (ρ = -0.40), SDNN pre-6MWT (ρ = 0.39), TP pre-6MWT (ρ = 0.38), Valsalva ratio (ρ = 0.39) and 30:15 ratio (ρ = 0.38) were all correlated with maximal walked distance. CONCLUSIONS: DM2 subjects presented abnormal HRV during and after submaximal exercise. Furthermore, autonomic control impairment in orthostatism, represented by lower global HRV (SDNN, Total power) and lower Ewing's indexes (Valsalva and 30:15 ratios), was associated with lower exercise capacity.