Evaluation of the Effectiveness of Transcutaneous Electrical Nerve Stimulation During Labor.
Condition: Midwifery; Pregnancy
Study type: Interventional

Summary: 
      This study evaluates the effectiveness of the Transcutaneus Electric Nerve Stimulation (TENS)
      during the labour. TENS is a low frequency electrotherapy technique, analgesic type,
      generally used in musculoskeletal pathology.

      The investigators will have three groups of participants to be administered the TENS, a
      different dose in two groups, while the third will correspond to placebo.

      The hypothesis of the study is to verify if the TENS is effective as a non-pharmacological
      method in the relief of pain during childbirth
    

Detailed description: 
      1. Background:

           Pain during labour is one of the most intense pain that many women could experience
           during their lives, and it can be influenced by the anatomical and physiological factors
           of the labouring women, and also, by their psychological experiences, as well as by
           cultural, social, and environmental factors.

           Neuraxial analgesia during labour is the most effective method for pain relief, but it
           appears to be associated with certain side effects, such as maternal hypotension,
           decreased uteroplacental perfusion, foetal bradycardia, fever, pruritus, an increased
           oxytocin requirement, a prolonged second stage of labour, a higher rate of operative
           delivery, and high costs.

           The use of non-pharmacological methods for pain relief includes a wide variety of
           techniques aimed at improving physical sensations and preventing psychoemotional
           perception of pain. Among the main nonpharmacological methods of pain relief at delivery
           is the application of Transcutaneous electrical nerve stimulation (TENS). Its
           application during childbirth is based on the Gait Control theory of pain of Melzack and
           Wall. According to their theory, the application of TENS reduces the excitability of the
           delta A and C pain fibers, thus reducing the amount of painful messages ascending the
           spinal cord. Activation of these fibers stimulates the release of natural pain
           inhibitors.

           Furthermore, many non-pharmacological methods of managing pain increase the satisfaction
           of women with their childbirth experience.

           TENS have used for labour analgesia and there are several studies which show its
           effectiveness. The effectiveness of TENS depends on the duration, frequency and
           amplitude of the stimulating current and the site of application of the electrodes. TENS
           can be administered by either dermatomal stimulation or by stimulation of acupuncture
           points for labour analgesia. In addition, all studies stated that it was safe and there
           was no side effects on the mother and the baby.

           This work was conducted to study the effectiveness of TENS on labour analgesia, maternal
           and fetal outcome using TENS by dermatomal stimulation technique. Thus, device will be
           used as follows:

           Through electrodes applied to the lower back, the parturient can control both
           parameters, the frequency and intensity of the low-voltage electrical impulses emitted
           from the TENS device. When applying to the lower back, the TENS unit emits electrical
           impulses which excite afferent nerves, and thus inhibit the transmission of painful
           stimuli arising from the uterus, vagina and perineum during labour. These electrodes are
           attached to the skin bilaterally at paravertebral positions T10 and S2.

           In the present study the investigators will use three equal devices (two different dose
           and one placebo) .They will be assigned a number that associate to each group of
           participants.

           Safety profile in the use of TENS:

           It is a non-invasive technique, easy to administer, without side effects or interactions
           with other drugs, it cannot produce toxicity in the tissue or cellular level.

           The current literature does not reflect any complications, either on the part of the
           pregnant woman and in the fetus, during the application of TENS in the labor phase.

           The use of TENS should be contraindicated in women whose gestational age does not exceed
           37 weeks, women with pacemakers and water births. It should not be applied in the
           maternal abdomen, at any time during pregnancy or childbirth, to avoid stimulation near
           the fetal heart.

        2. Objectives:

           Primary aim:

             -  To know if the application of TENS is effective in reducing pain during childbirth.

           Secondary aim:

             -  To determine the most effective dose in the use of TENS in pregnant women during
                labor.

             -  To analyze the degree of satisfaction of the pregnant women who participate in the
                study.

             -  To evaluate whether the use of TENS reduces the dose of the painkillers during
                childbirth.

        3. Material and Methods:

      This study is a triple blind randomized trial with concealed allocation, assessor blinding
      for some outcomes, and intention-to-treat analysis.

      It was accepted by the Ethic Committee of the Hospital Complejo Hospitalario Universitario
      Insular Materno Infantil of Las Palmas de Gran Canaria, Canary Islands, Spain, with
      registration number CEIm-CHUIMI-2016/875.

      3.1. Allocation: All participants will be recruited from a group of women admitted to the
      hospital. If the pregnant woman meets the inclusion criteria, she will be asked to
      participate in the study. If yes, they must sign the informed consent, approved by the same
      ethical committee of the hospital.

      The assignment to each group was made through the website www.random.org to perform
      randomization. In addition, each group has a different TENS, which has the group number.
      Participants in all groups will receive all the other routine obstetric care.

      3.2. Sample size determination: The sample size and power calculations were performed using
      the software GRANMO 7.11. Calculations were based on detecting differences of 2 units in a 10
      numerical pain rate scale at post-data, assuming a standard deviation of 1.9, a 2-tailed
      test, an alpha level of 0.05, and a desired power of 80%. These assumptions generated a
      sample size of 63 subjects, 21 per group.

      There is a specialiced nurse that will supervised the correct functionality every day. He
      will be responsible for resolving dispositive problems like low charge or insufficient
      electrodes.
    

Intervention name(s): TENS 1; TENS 2; Placebo TENS
Intervention type(s): Device; Device; Device
Intervention description(s): A portable TENS unit will be used by the principal investigator to apply the experimental intervention. Two pairs of electrodes measuring 5 x 9 cm will be fixed on the paravertebral regions of the participants of the experimental group using hypoallergenic surgical tape. Two paired electrodes will be placed 1 cm laterally on either side of the spine at the T10 to L1 and S2 to S4 levels.; An intervention similar to arm 1 will be performed but with different doses.; An intervention similar to arm 1and 2 will be performed but,in this case, it is a sham device.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Transcutaneous electrical nerve stimulation; TENS; Analgesia; Labour pain; Physical therapy modality