Hemodynamic Effects Induced by Transcutaneous Electrical Nerve Stimulation in Apparently Healthy Individuals: A Systematic Review With Meta-Analysis

Objective: To determine the immediate effects of transcutaneous electrical nerve stimulation (TENS) on heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in apparently healthy adults (age >18y). Data Sources: The Cochrane Library (online version 2014), PubMed (1962-2014), EMBASE (1980-2014), and LILACS (1980-2014) electronic databases were searched. Study Selection: Randomized controlled trials were included when TENS was administered noninvasively with surface electrodes during rest, and the effect of TENS was compared with that of control or placebo TENS. A sensitive search strategy for identifying randomized controlled trials was used by 2 independent reviewers. The initial search led to the identification of 432 studies, of which 5 articles met the eligibility criteria. Data Extraction: Two independent reviewers extracted data from the selected studies. Quality was evaluated using the PEDro scale. Mean differences or standardized mean differences in outcomes were calculated. Data Synthesis: Five eligible articles involved a total of 142 apparently healthy individuals. Four studies used high-frequency TENS and 3 used low-frequency TENS and evaluated the effect on SBP. Three studies using high-frequency TENS and 2 using low-frequency TENS evaluated the effect on DBP. Three studies using high-frequency TENS and 1 study using low-frequency TENS evaluated the effect on heart rate. A statistically significant reduction in SBP (-3.00mmEg; 95% confidence interval [CI], 5.02 to 0.98; P=.004) was found using low-frequency TENS. A statistically significant reduction in DBP (1.04mmHg; 95% CI, 2.77 to 0.03; /2=61%; P=.04) and in heart rate (-2.55beats/min; 95% CI, 4.31 to 0.78; /2=86%; P=.005]) was found using both frequencies. The median value on the PEDro scale was 7 (range, 4-8). Conclusions: TENS seems to promote a discrete reduction in SBP, DBP, and heart rate in apparently healthy individuals. (C) 2016 by the American Congress of Rehabilitation Medicine