Effects of TENS and IES on the Autonomous Balance of Normotens Volunteers and Hypertensive Patients

Universidade Federal de Santa Maria60 enrolled

Overview

Hypertension is considered a serious public health problem. The imbalance in autonomic nervous system (ANS) activity is one of the main triggers in the development and maintenance of hypertension. The non-pharmacological management of this disease is an important resource, especially in refractory hypertensive patients or in hypertensive crises, where the pharmacological treatment does not present an efficient response. It is known that transcutaneous electrical nerve stimulation (TENS) is capable of modifying the autonomic balance, however, the effects of Interferential electrical stimulation (IES) on this system in normotensive and hypertensive volunteers are not yet known. These electrotherapeutic resources may be a non-pharmacological tool supporting the management of hypertension. The objective of this research is to study the effects of different TENS and IC parameters on cardiovascular variables of normotensive volunteers and hypertensive patients.

Each volunteer will perform three assessments with a one-week interval. Each assessment will include assessment of autonomic balance, blood pressure, and blood collection (catecholamines). Interventions (placebo, low frequency TENS and IES) will be randomized. Volunteers will be accommodated in the supine position. With properly sanitized skin (70% alcohol) and self-adhesive electrodes (5x5 area) will be positioned in the cervical paravertebral region. All participants will be submitted to a placebo TENS session, a low frequency TENS session (TENS, 10 Hz/200μs) and an IES session (STEIN et al., 2012). The sessions will take place in the morning in a 12-hour fast, lasting 30 minutes, in an air-conditioned place (23ºC).

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Interventions

Transcutaneous nervous electric stimulation (TENS)DEVICE

TENS (Frequency 10 Hz or 100Hz /duration 200μs, Endophasys nms 0501® model, KLD Biosystems, Amparo, SP, Brazil) will be applied with intensity between 1 to 60 mA and the current will be adjusted every 5 minutes at the sensory threshold level muscle contraction or according to the tolerance to the stimulus informed by the volunteers. TENS will be applied in bilateral paravertebral region of C7 to T4 or long the brachial plexus and sciatic plexus.

Interferential electrical stimulation (IES)DEVICE

The IES (Endophasys nms 0501®, KLD Biosystems, Amparo, SP, Brazil) will be applied in continuous mode with biphasic pulses. Bipolar electrodes with slope of 1/5/1. The rest of the parameters will be set to 4000 Hz, AMF of 100 Hz and the AMF variation of 25 Hz. The effect of the current will be adjusted by the intensity, it should produce paresthesia stimuli, without pain and below the motor threshold. Adhesive electrodes (MultiStick®, Axelgaard Manufacturing CO, Ltd, Fallbrook, CA, USA) will be housed in the paravertebral region, between C7 (Channel 1) and T4 (Channel 2). (SANTOS et al., 2013)

TENS and IES PlaceboDEVICE

Same protocol without electrical output.

Eligibility

Sex: ALLMin age: 20 YearsMax age: 65 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Both sexes; * Normal blood pressure (PAS \<130 mmHg; PAD \<85 mmHg) or Previous Hypertension diagnosis, systolic blood pressure (SBP) \> 140 mm Hg and/or diastolic blood pressure (DBP) \>90 mm Hg and clinical stability with no change in medications for at least 2 months preceding the study; * The subjects that joined the study will be alphabetized volunteers; * Age between 20 and 65 years old; * With no symptoms of skeletal muscle disorders; * No previous performing cardiovascular surgery; * No previous diagnose of rheumatic, neurological, oncological, immune or hematologic diseases; * Without evidence of psychiatric diseases and/or cognitive déficit; * Non-Smoker; * Volunteers with a body mass index (BMI: kg/m2) greater than 35 will not be included in the study Exclusion Criteria: * On the day of the assessments who have consumed of the alcoholic drink, caffeine and citrus juice and who have performed intense physical activities 48 before the examination

Outcomes

Primary Outcomes

Systemic arterial pressure (mmHg)

Systemic arterial pressure (SBP) will be evaluated by an Ambulatory Blood Pressure Monitor (ABPM) (NOBRE et al., 2011). Micromed and version 5.0.1.52 equipment will be used. Blood pressure monitoring using ABPM will be performed every 10 min throughout the experiment, which has an estimated time of two hours.

Time frame: SBP will be evaluated 1 hours after the interventions

Secondary Outcomes

Blood collection - catecholamines (pg/mL)

Plasma levels of catecholamines (dopamine, epinephrine and norepinephrine) will be evaluated before and after HPLC (High Performance Liquid Chromatography) interventions. Blood with heparin will be homogenized and immediately transferred to a special tube containing 120 μL of EGTA/GSH (reduced glutathione) solution. After being centrifuged and the plasma transferred to a plastic tube, it is placed in a freezer (-80ºC).

Time frame: Blood collection (catecholamines) will be evaluated 1 hours after the interventions

Heart Rate Variability (n.u.)

The autonomic balance evaluate by heart rate variability (HRV) and the heart rate signal will be purchased through a pulse frequency meter mark Polar model 810i (GAMELIN et al., 2006). The acquisition of ECG signal (sample rate-1 kHz) of the time series of RR will be purchased in continuous intervals (10 min). Data Will be transferred to a computer and RR intervals. They will be processed to calculate HRV parameter using the HRV analysis software KUBIOS. HRV will be analyzed in the time and frequency domain, using the area of greatest stability in RR intervals corresponding to 5 min of recordings (containing at least 256 consecutive beats) during controlled breathing. Volunteers Will remain in a supine position at rest for 10 min and afterwards, data will be collected with controlled breathing (12 breaths per minute; I/E:2/3) (STEIN et al., 2011). Values expressed in Total Power (ms2) and normalization unit (n.u.) (GAMELIN et al., 2006).

Time frame: HRV will be evaluated 1 hours after the interventions