Estimulação elétrica nervosa transcutânea para dor abdominal após o parto cesariana : ensaio clínico randomizado e revisão sistemática com meta-análise

Abstract

Cesarean section is a surgical procedure associated to high intensity abdominal pain, not relieved by drugs. Therefore, non-pharmacological strategies for analgesia has been used, as Transcutaneous Electric Nerve Stimulation (TENS). This study aimed to analyze the analgesic effect of TENS on abdominal pain after cesarean applied in abdominal or paravertebral region and in motor or sensitive amplitude, as its analgesic effect on pain intensity (at rest and during movement), deep pain intensity, cutaneous sensitivity, pressure pain threshold and range of motion, and analyze risk of bias, as scientific data of clinical trials which investigated TENS effects on abdominal pain after cesarean section. For meta-analysis, a systematic search in six databases, hand search and Google Scholar was performed. Ten randomized clinical trials published until December 2016, which investigated TENS effects on abdominal pain relief after cesarean compared to control or placebo group were included. Risk of bias analysis using Cochrane Collaboration tool and meta-analysis of pain intensity data was performed based on four of the included studies. On randomized double-blind clinical trial, the following outcomes (and their respective assessment instruments) were measured before and after a single TENS session: incisional and deep pain intensity at rest and during movement (Numerical Rating Scale), pressure pain threshold (digital algometer), cutaneous sensitive threshold (Von Frey filaments), temporal summation (temporal summation test) and range of motion for anterior flexion, right and left trunk rotation (fleximeter). On clinical trial, 80 cesarean postpartum women were included and allocated in four groups (peri-incisional (n=20), sensitive paravertebral (n=20), motor paravertebral (n=20) and placebo TENS (n=20)). On intragroup analysis, the following changes were observed: pain intensity decrease on both three groups treated with active TENS, at rest (peri-incisional and motor paravertebral group) and during movement (sensitive paravertebral group); cutaneous sensitive threshold decrease in one of the points close to the incision on peri-incisional group and in two points far from incision (periincisional and motor paravertebral groups). On pressure pain threshold, pressure increased on peri-incisional group and pressure pain intensity decreased on sensitive and motor paravertebral groups. Range of motion for right trunk rotation increased on sensitive paravertebral group, and pain intensity decreased during left trunk rotation (peri-incisional, sensitive and motor paravertebral groups) and right trunk rotation (peri-incisional and sensitive paravertebral groups). There was no difference on temporal summation. On clinical trial, active TENS favored pain intensity reduction, increase in pressure pain threshold, cutaneous sensitivity and lower pain during the assessed movements on the major active TENS groups. In addition to that, TENS applied on paravertebral region using sensitive amplitude seems to provide better analgesic effect. Meta-analysis results evidenced non-effectiveness of TENS on pain intensity decrease compared to placebo (MD = 2.08, 95% CI: -0,13 to 4,28, p = 0,07, I2 = 99%) and low quality of evidence was verified.