The Impact of Transcutaneous Electrical Nerve Stimulation (TENS) on Acute Pain and Other Postoperative Outcomes: A Systematic Review with Meta-Analysis

This study aimed to investigate the efficacy and safety of transcutaneous electrical nerve stimulation (TENS) in postoperative acute pain control. PubMed, Scopus, and Cochrane Library were searched on 1-8 December 2022, for randomized controlled trials on the analgesic effects of TENS. The outcomes were pain intensity and opioid use (primary), and postoperative (PO) adverse events, blood pressure, and the duration of hospital stay (secondary); PROSPERO CRD42022333335. A total of 40 articles were included in the meta-analysis. Pain intensity at rest and during coughing for all types of surgeries combined was lower in the TENS group (standardized mean difference (SMD) = -0.51 [-0.61, -0.41], p < 0.00001, 29 studies, and -1.28 [-2.46, -0.09], p-value = 0.03, six studies, respectively). There was a statistically significant decrease in morphine requirements, as well as in the incidence of postoperative nausea and vomiting, dizziness, and pruritus. There was no difference between the groups in postoperative pain intensity during walking, in blood pressure, and only a borderline difference in the length of hospital stay. The subgroup analysis by surgery type did not show significant differences between the groups in pain severity at rest. Thus, TENS has a potential for pain control and postoperative recovery outcomes.

Characterising the Features of 381 Clinical Studies Evaluating Transcutaneous Electrical Nerve Stimulation (TENS) for Pain Relief: A Secondary Analysis of the Meta-TENS Study to Improve Future Research

Background and Objectives: Characterising the features of methodologies, clinical attributes and intervention protocols, of studies is valuable to advise directions for research and practice. This article reports the findings of a secondary analysis of the features from studies screened as part of a large systematic review of TENS (the meta-TENS study). Materials and Methods: A descriptive analysis was performed on information associated with methodology, sample populations and intervention protocols from 381 randomised controlled trials (24,532 participants) evaluating TENS delivered at a strong comfortable intensity at the painful site in adults with pain, irrespective of diagnosis. Results: Studies were conducted in 43 countries commonly using parallel group design (n = 334) and one comparator group (n = 231). Mean ± standard deviation (SD) study sample size (64.05 ± 58.29 participants) and TENS group size (27.67 ± 21.90 participants) were small, with only 13 of 381 studies having 100 participants or more in the TENS group. Most TENS interventions were ‘high frequency’ (>10 pps, n = 276) and using 100 Hz (109/353 reports that stated a pulse frequency value). Of 476 comparator groups, 54.2% were active treatments (i.e., analgesic medication(s), exercise, manual therapies and electrophysical agents). Of 202 placebo comparator groups, 155 used a TENS device that did not deliver currents. At least 216 of 383 study groups were able to access other treatments whilst receiving TENS. Only 136 out of 381 reports included a statement about adverse events. Conclusions: Clinical studies on TENS are dominated by small parallel group evaluations of high frequency TENS that are often contaminated by concurrent treatment(s). Study reports tended focus on physiological and clinical implications rather than the veracity of methodology and findings. Previously published criteria for designing and reporting TENS studies were neglected and this should be corrected in future research using insights gleaned from this analysis.

Transcutaneous Electric Nerve Stimulation Reduces Pathological Sensation of Mesh One Week after Open Inguinal Hernia Surgery: Follow-Up Results from a Randomized, Double Blind and Placebo-Controlled Trial

Background and Objectives: Quality of life (QoL) and chronic pain are important outcomes following hernia surgery. The long-term effects of Transcutaneous Electric Nerve Stimulation (TENS) on postoperative recovery are not well known. In this trial we investigated the role of TENS on QoL and on the incidence of chronic pain following inguinal hernia repair with mesh. Materials and Methods: A total of 80 male patients with elective primary unilateral hernia Lichtenstein repair were randomly allocated to receive TENS or a placebo-TENS procedure. The TENS group received conventional TENS twice a day on the first and second postoperative days. The intensity was set at 0–0.5 mA in the placebo-TENS group. General and hernia-specific QoL, as well as the incidence of chronic pain were assessed using SF-36v2 and the Carolinas comfort scale. Results: Less sensation of mesh was reported by the TENS group patients one week after surgery. At this time point, the mean sensation score was 6.07 ± 8.88 in the TENS group and 14.08 ± 16.67 in the placebo-TENS group (p = 0.029). Although at two days and one week postoperatively, TENS group patients tended to have less pain, less movement restrictions and better overall hernia-specific QoL, the differences were not statistically significant. At 6 months postoperatively, no incidence of chronic pain was found in either the placebo-TENS or TENS group. Conclusions: Conventional TENS applied in the early postoperative period following inguinal hernia repair with mesh was found to reduce mesh-related foreign body sensation one week after surgery. Promising results were also found for other QoL domains.

Transcutaneous Electric Nerve Stimulation Reduces Acute Postoperative Pain and Analgesic Use After Open Inguinal Hernia Surgery: A Randomized, Double-Blind, Placebo-Controlled Trial

In this randomized, double-blind, placebo-controlled trial, we evaluated the role of transcutaneous electrical nerve stimulation (TENS) in the multimodal treatment (nonopioid analgesics and kinesiotherapy) of postoperative pain following open inguinal hernia repair. In total, 80 males participants with elective primary unilateral hernia Lichtenstein repair were randomly allocated to receive TENS or a placebo-TENS procedure. The TENS group received local and segmental conventional TENS on the first and second postoperative days. In the placebo-TENS group, intensity was set at 0 to 0.5mA. Change of pain level at rest, when walking, when standing up from bed, pressure algometry parameters and additional analgesic use were the main outcomes. Reduction of VAS pain score and absolute and relative pain relief were observed in the TENS group following the procedures compared to the placebo-TENS group (P< .001). The pressure pain threshold and maximal tolerable pressure in the hernia side were equal before the TENS procedure in both groups (P= .84), but after the procedure, these were higher in TENS group (P< .001). Additional nonopioid analgesics requirements were lower in the TENS group on the first and second postoperative days (P< .001). TENS is a safe procedure that can reduce postoperative pain and analgesic use after open inguinal hernia repair. The study was registered in the database of clinicaltrials.gov (register number NCT03739060). PERSPECTIVE: This article presents TENS as a safe and effective nonpharmacologic intervention to reduce postoperative pain after open inguinal hernia repair. TENS could be used in daily practice as part of a multimodal postoperative pain treatment, especially for patients suffering from hyperalgesia.

Effect of TENS on Postoperative Pain and Pulmonary Function in Patients Undergoing Coronary Artery Bypass Surgery

BACKGROUND

The aim of this study was to determine the effect of electrical nerve stimulation on pain intensity and pulmonary function in patients undergoing coronary artery bypass surgery.

MATERIALS AND METHODS

In a randomized clinical trial, a total of 100 patients undergoing coronary artery bypass surgery at Masih Daneshvari Hospital, Tehran, Iran, from February to May 2014, were divided into two groups. In the intervention group (n = 50), patients received routine care along with transcutaneous electrical nerve stimulation (TENS) immediately after admission to the intensive care unit (ICU). In the placebo group (n = 50), patients only received routine care. The pain intensity was measured using a visual analog scale (VAS) every 6 hours for 72 hours after surgery in two conditions of rest and coughing. Pulmonary function was assessed through forced expiratory volume in 1 second (FEV1) and forced volume capacity (FVC) at 24, 48, and 72 hours after surgery. Age, gender, body mass index, narcotic consumption, ICU length of stay, and requests for chest radiographs were recorded. The statistical level of significance was set at p < .05.

RESULTS

There were no significant differences between the two groups in terms of age, gender, and body mass index (p > .05). Pain intensity was significantly lower in the TENS group than the placebo group in both resting and coughing condition (p < .05). FVC and FEV1 were significantly better and faster in the TENS group than in the placebo group at 24, 48, and 72 hours after surgery (p < .05). Patients in the TENS group had significantly lower narcotic use and requests for chest radiographs compared with placebo group.

CONCLUSIONS

TENS may reduce postoperative pain in resting and coughing conditions, improve pulmonary function, and reduce narcotic use in patients undergoing coronary artery bypass surgery.