Transcutaneous Electrical Nerve Stimulation
Transcutaneous electrical nerve stimulation (TENS) is the transmission of low-voltage electrical impulses from a handheld battery-powered generator to the skin via surface electrodes. Long used in much of the world for control of chronic or postsurgical pain as an adjunct to or replacement for pain medication, TENS was introduced into maternity care in Scandinavia in the 1970s. Today it is widely used and rated highly by users in the United Kingdom, Scandinavia, parts of Canada, and in other countries. In fact, TENS units, designed for convenient use by the woman in labor, are available for rent without a doctor's or midwife's order in drugstores and medical equipment companies in those countries. TENS is not widely used for labor pain in the United States, although physical therapists can provide TENS units and teach expectant parents how to use them.
To relieve labor pain, one pair of electrodes is placed paravertebrally at the level of T10-L1 and another at the level of S2 to S4 (Figure 2). The woman controls the intensity of the current by turning a dial and varies the stimulation pattern with a thumb switch or by adjusting dials on her TENS unit. TENS causes a buzzing or prickling sensation that may reduce her awareness of contraction pain.
Figure 2.
A TENS unit in use.
Effectiveness of TENS in Reducing Pain and Suffering During Labor
A 1997 systematic review of 8 trials of TENS for labor,[60] including a total of 812 women, found that women's ratings on a visual analog scale during labor or postpartum assessments by the women indicated no less pain with TENS than usual care. However, analgesics were used less by TENS users (OR 0.57, 95% CI 0.34-0.96), and 54% of TENS users stated they would use it in a future labor (compared with 32% who had "sham" TENS).
One more recent trial of TENS,[61] including 104 women, found shorter duration of first-stage labor among nulliparas (12 ± 4 hours vs 14 ± 4 hours, P < .001) and multiparas (9 ± 3 vs 10 ± 3, P < .005), and later introduction of pain medication (5.2-cm dilation vs 2.5 cm among nulliparas, P < .0001; 7.1 cm vs 4 among multiparas, P < .0001) in the TENS users than the control groups. The majority of all TENS users considered TENS effective for pain relief and would use it again in future labors.
Experienced practitioners state that TENS may be more effective if initiated in early labor, presumably to allow for a build-up in endorphin production before the pain becomes severe. Furthermore, TENS may be more effective for relief of back pain than labor pain in general, but only 2 older studies have investigated this possibility.[62,63]
The satisfaction expressed by women with TENS may relate to other factors beside pain relief. TENS allows the woman to be in control of its use, allows ambulation, has no effects on her mental state, and gives an option to those who wish to avoid or delay medications.
There are few potential side effects from TENS when used by healthy individuals. Although rare if used with electronic fetal-monitoring equipment, TENS may interfere with the output from the monitor, in which case, either the TENS or the monitor should be discontinued or used intermittently. There is expense involved in renting or purchasing the units, and presently, it is difficult for Americans to obtain the units that are designed for use during labor. At present, suppliers of obstetrical TENS units can be found on the Internet.
TENS provides modest pain relief benefits and is a satisfying option for most women who use it. Its efficacy in relieving back pain deserves further study.
J Midwifery Womens Health. 2004;49(6) © 2004 Elsevier Science, Inc.
Cite this: Update on Nonpharmacologic Approaches to Relieve Labor Pain and Prevent Suffering - Medscape - Nov 01, 2004.
Comments