Neuromuscular Electrical Stimulation During Hemodialysis in Peripheral Muscle Strength and Exercise Capacity

Clinical trial, randomized, parallel, open, two-arm, blinded assessor, prospective.

Patients with chronic kidney disease on hemodialysis, divided equally into two groups: group of high frequency and intensity neuromuscular electrical stimulation (HG) and a group of low frequency and intensity neuromuscular electrical stimulation (LG).

Randomization was stratified according to gender using 4 block. Drug treatment established for both groups remained unchanged throughout the study period.

Assessments were made on the first working day after hemodialysis, following notification and consent of the medical teams. Patients initially underwent anthropometric measurements and vital signs, later carried out the assessment of peripheral muscle strength, pulmonary function test, submaximal exercise capacity and quality of life questionnaire and depression. After these procedures, the patients were randomized to select HG or LG by opaque envelopes. These evaluations were performed at baseline and after 12 sessions of completion of the protocol.

Furthermore, it was asked to chronic kidney disease (CKD) patients on hemodialysis who presented their latest blood tests clearance index (Kt / V), creatinine, glomerular filtration rate. The evaluation of pro-inflammatory cytokines and regulatory plasma, the enzyme markers of muscle tropism, oxidative stress and muscle injury in patients with CKD was always held at the end of each month as routine clinical.

Two groups conducted training with peripheral electrical stimulation isometric form in lateral and medial bilaterally vast, held three times a week, lasting an hour, the first two hours of dialysis.

Will be applied using portable stimulators with 4 channels. The parameters are:

• HG: frequency of 50 Hertz (Hz), pulse width of 400 microseconds (μs), rise time and fall time of 2 seconds (s), on:off stimulation, initially with a 1:2 relation in the first week (10s of stimulation and 20s of rest, with the objective to adapt and minimize the effects of muscular fatigue), to be increased to a 1:1 relation in the second week (10s of stimulation of and 10s of rest).
• LG: frequency of 5 Hz, on:off stimulation time of 1:3 (10s of stimulation and 30s of rest) with pulse duration of 100 μs.

For both groups, the current intensity was adjusted individually in the first application. In HG, the intensity was gradually increased until visible muscle contraction could be observed: this was the maximum intensity tolerated by the patient. In LG, the intensity was the least noticeable by the patient. These values were monitored for further calculation of intensity evolution throughout the training program.

The blood pressure (BP) will be measured at baseline, and 30 minutes after the end of the session and heart rate (HR) will be monitored every 10 minutes using an oximeter.

In each session there will be a warm-up period, training and slowdown. The first minute will starting with 20% of the intensity value used in the last session with a gradual increase of 20% per minute until 5 minutes, followed by a 50 minute training period and finishing with a 5 minute recovery period gradual reduction of 20% intensity every minute.

Before and after training, patients will be asked about their feelings of fatigue / tiredness of the lower limbs using the modified Borg scale. If reporting muscle pain, the intensity will be assessed by visual analogue scale visual analogue scale (VAS).

They are recruited 76 patients of both sexes, accepted for hemodialysis treatment for at least 6 months. 38 patients are allocated for the HG and 38 to LG.

The sample size calculation was performed in order to advance in GPower 3.1 program based on the results obtained in the study conducted neuromuscular electrical stimulation during hemodialysis in patients with chronic kidney disease. the values of peripheral muscle strength were used before and after treatment respectively 185.4 ± 53 and 222.4 ± 36.6 and the values for the assessment of pre exercise capacity (401.3 ± 55) and post (428.9 ± 69.2) waiting for electrostimulation observe a similar effect. Using an error of 5% (80% test power), it was determined the need for inclusion of 12 patients for the variable peripheral muscle strength and 34 patients for exercise capacity. Recital 10% loss would require the evaluation and treatment of 14 and 38 patients to check the effect on peripheral muscle strength and on exercise capacity respectively.

Safety:

The main negative effect of electrical stimulation is muscle discomfort and / or fatigue of the lower limbs during and after training. Patients will be were asked at the beginning and end of the training on their sense of fatigue / tiredness members, as well as on the feeling of muscle pain. In addition, the current was adjusted individually and gradually increased shape with patient consent. In the case that patients feel a discomfort, the intensity of electric current was reduced, and if required the protocol was stopped by improvement of symptoms.

Statistical analysis:

The data were systematized in IBM SPSS (Statistical Package for Social Sciences) version 20.0. The data were presented as mean ± standard deviation or median and interquartile range and frequency. To verify the data normality the Shapiro-Wilk test was applied. To compare the behavior of the variables between groups was used independent t test for parametric variables and test U Mann Whitney for nonparametric. As for comparing the average pre and post use of electrical stimulation was used ANOVA test for repeated measurements or Friedman test and to check if there is a relationship between respiratory muscle strength and exercise capacity was used Pearson correlation coefficient or Spearman, according to the normal distribution of data. The significance level for the statistical treatment was 5% (p <0.05).