Ž .International Journal of Gynecology & Obstetrics 60 1998 251]255

Article

Ž .Transcutaneous electrical nerve stimulation TENS foradjuvant pain-relief during labor and delivery

B. Kaplana,b,U, D. Rabinersona, S. Luriec, J. Bar a,b, U.R. Krieser d, A. Neria,b

aDepartment of Obstetrics and Gynecology, Rabin Medical Center, Beilinson Campus Petach Tiq®a, IsraelbSackler Faculty of Medicine, Tel A®i® Uni®ersity, Tel A®i®, Israel

cDepartment of Obstetrics and Gynecology, Kaplan Hospital, Recho®ot, IsraeldPain Management Center, Melbourne, Australia

Received 23 June 1997; received in revised form 16 November 1997; accepted 1 December 1997

Abstract

Ž .Objecti®e: We examined the efficacy of transcutaneous electrical nerve stimulation TENS in general and the newŽ .Freemom TENS device LifeCare, Israel in particular, for pain relief during labor and delivery. Methods: The study

Ž . Ž .group consisted of 104 women. Forty-six nulliparas 44.2% and 58 multiparas 55.8% , all of whom used the TENSdevice for pain relief during labor. All participants completed a questionnaire on the degree of pain relief affordedthem by TENS during the delivery and related questions. The objective evaluation was based on the documented

Žlabor and delivery parameters including medical interventions during delivery. Results: The majority of subjects 72%.of the nulliparas and 69% of the multiparas considered TENS effective for the relief of pain during labor. Most of

Ž .them 67% of the nulliparas and 60% of the multiparas responded positively to the use of TENS in future deliveries.Sixty-five percent of the multiparas considered TENS at least as effective as the other pain relief methods they hadused before. TENS significantly reduced the duration of the first stage of labor P-0.001 for nulliparas, P-0.005 formultiparas and it significantly decreased the amount of analgesics administered to individual patients. No significantdifference was found in fetal heart rate tracings, Apgar scores and cord blood pH between the study group and anequal number of matched controls who used other forms of pain management. Conclusions: TENS is an effectivenon-pharmacological, non-invasive adjuvant pain relief modality for use in labor and delivery. TENS applicationreduced the duration of the first stage of labor and the amount of analgesic drug administered. There were noadverse effects on mothers or newborns. Q 1998 International Federation of Gynecology and Obstetrics

Keywords: TENS; Delivery; Labor; Pain; Treatment

U Corresponding author. Tel.: q972 3 9377534; fax: q972 3 6354254.

0020-7292r98r$19.00 Q 1998 International Federation of Gynecology and ObstetricsŽ .P I I S 0 0 2 0 - 7 2 9 2 9 7 0 0 2 7 5 - 0

( )B. Kaplan et al. r International Journal of Gynecology & Obstetrics 60 1998 251]255252

1. Introduction

Transcutaneous electrical nerve stimulationŽ .TENS is a non-pharmacological, non-invasivepain-relief method that has been proven effective

w xfor a variety of conditions 1,2 . It has also beenfavorably reported for use during labor and deliv-

w xery, with an efficacy rate as high as 96% 3,4 .When TENS was applied, the duration of laborwas shorter and there was no increase in patho-logical cardiotocographic findings for either

w xprimiparas or multiparas 5 . Most patients weresatisfied with TENS and expressed a desire to use

w xTENS again for their next labor 6 .Despite these findings, the use of TENS has

w xreceived little attention in the US 6 and hasgained little popularity among obstetricians

w x w xworldwide 3 . Two later reports 7,8 have ques-tioned the use of TENS as an efficacious tech-nique of pain relief during labor.

However, our group has since demonstratedexcellent results in patients with primary dys-

w xmenorrhea who used TENS 9,10 . Based on thesew xresults and our overall experience 11 , a new

TENS device was designed according to our spec-ifications for use during labor and delivery. Thefindings of our evaluation are described herein.

2. Materials and methods

The study population included 104 of the 1953Ž .parturients 18.8% admitted to the delivery room

of Rabin Medical Center, Beilinson Campus fromAugust 1995 to February 1996; all of whom wereoffered the use of TENS for pain relief duringlabor. Each received a full explanation of themechanism and mode of action of TENS. The

ŽTENS model employed in this study Freemom,.LifeCare, Israel was specifically designed to sup-

ply enough current to satisfy the most stringentdemands during contractions and automaticallyreducing stimulation levels to a preset levelbetween contractions to maintain endorphins pro-duction.

Admission criteria for the study were regularŽuterine contractions at least three within a 10-min

.period by external tocography , cervical dilatationof at least 2 cm, cervical effacement of at least

80%, intact membranes and an expressed desirefor pain relief on admission.

Ž .Of the 104 patients, 46 44.2% were nulliparasŽ .and 58 55.8% multiparas. At entry to the deliv-

ery room, each patient was fitted with obstetricŽelectrodes laterally to the mid-line between S2

.and T10 and the TENS device was connected tothe electrodes. The patient was handed a ques-tionnaire to evaluate TENS efficacy in relievingpain during labor and delivery. The items alsocovered demographic data and medical andobstetric history. TENS efficacy during labor wasevaluated by having each participant rank thelevel of pain sensation every 2 h on a scale of 1Ž . Ž .very low to 10 very high . Patients were able tocontrol the device manually and the readings

Žwere taken while TENS was turned on, or off by.the patient , for the time that it took two contrac-

tions to occur. We arbitrarily defined TENS asefficacious if the subject consistently scored thepain level as lowered by at least four points.Multiparous subjects were asked to record thetype of analgesia used during previous deliveriesand to compare their efficacy to the pain manage-ment achieved with TENS.

Ž . ŽOn a scale of 1 no difference to 10 much.more efficient , TENS was arbitrarily defined as

efficacious when the patient ranked it higher bysix points or more over the other forms of painmanagement. All subjects were asked if theywould use TENS for future deliveries.

Patients who did not obtain sufficient pain re-lief using TENS, were allowed to choose one ofthe two analgesic pain relief methods used in ourdelivery room: meperidine q promethazine orepidural block. For those who chose the former,TENS was continued as an adjuvant therapy. Thesubjective pain measurements were performed aslong as the patient was using TENS alone. Theywere stopped once the patient elected to use anadditional pain-relief method.

To gain an objective picture, the followingparameters were recorded for each participant:

Žduration of first stage delivery from admission to.the delivery room to full dilatation ; appearance

of pathological patterns in the fetal heart rateŽ .FHR tracing; and degree of cervical dilatationand effacement at the time the patient requested

( )B. Kaplan et al. r International Journal of Gynecology & Obstetrics 60 1998 251]255 253

other pain relief therapy. If meperidine qpromethazine was chosen, the number of timesmedication was requested; Apgar scores at 1 and5 min; and cord blood pH.

To further validate the results, the sameparameters were recorded from an equal numberof control patients that were matched for age,parity and gestational week, who used onlymeperidineqpromethazine or epidural block forpain management.

All study participants signed an informed con-sent form.

Statistical analysis was performed using Stu-dent’s t-test or x 2-test as indicated. A P valueless than or equal to 0.05 was considered signifi-cant.

3. Results

The mean age of the participants was 24"3.5Ž . Žyears range 18]40 years , parity 2.3"1.1 range

.0]5 and gestational age at delivery 40.5"1.5Ž .weeks range 38]42 .

Data were gathered for nulliparas and multi-paras separately. TENS was considered effica-

Žcious i.e. it reduced the level of pain by 4 points.or more on a scale of 1]10 by 72% of the

Ž .nulliparas 33r46 and 69% of the multiparasŽ .40r58 . Most of the participants in both sub-

Žgroups who favored TENS 67% of the nulliparas,.60% of the multiparas stated that they would use

TENS again for their next labor. In the multi-

Ž . Žparous group, 65% 38r58 favored TENS at.least a 6-point higher rating over other types of

intrapartum analgesics to which they had beenpreviously exposed.

Table 1 outlines the effects of TENS through-out labor. Compared to the group of match con-trols, the use of TENS significantly reduced the

Žduration of the first stage of labor, nulliparas,720"235 min in the study group, 856"255 minin the control group; for multiparas, 520"163min and 612"184 min, respectively.

Of the TENS users, 67% of the nulliparas and60% of the multiparas asked for additional anal-

Žgesia meperidine q promethazine or epidural.block . However, all these requests were made at

a significantly higher degree of cervical dilatationŽcompared to the controlled group nulliparas, 5.2

"1.1 cm and 2.5"0.5 cm; multiparas, 7.1"2.1.cm and 4.0"1.5 cm, respectively .

Rates of pathological FHR tracings, as well as1 and 5 min Apgar scores and cord blood pH,were similar in the TENS participants and thecontrols.

4. Discussion

Only a small percentage of women who deliverin hospitals receive no pain medications. Themost frequently employed form of pain control

Ž .during labor is epidural analgesia 50% , followedŽ . w xby narcotics 26% , 12 . Although these agents

apparently meet the needs of most parturients,

Table 1Effect of TENS on intrapartum parameters

Study group Control group P P

Ž . Ž .Nulliparas Multiparas Nulliparas Multiparas Nulliparas Multiparas

Duration of first 720"235 min 520"163 min 856"255 min 612"184 min 0.001 0.005stage

Cervical dilatation 5.2"1.1 cm 7.1"2.1 cm 2.5"0.5 cm 4.0"1.5 cm -0.000 -0.000when adjuvant analgesiarequested

Ž . Ž .Desire for additional 31r46 67% 35r58 60%Ž .analgesia m

( )B. Kaplan et al. r International Journal of Gynecology & Obstetrics 60 1998 251]255254

they are not without contraindications and com-w xplications 13 . This was the rationale for our

search for an alternative, safe and non-pharmaco-logical method of intrapartum pain relief.

TENS operates by the application of electricalimpulses through conductive electrodes placed onthe skin. Analgesia is attributed either to the

Žincrease in A-fiber transmission which blocks.pain impulses to the brain , the ‘gate theory’ of

w xMelzack and Wall 14 , or to the stimulation ofw xthe local release of endorphins 15 . TENS has

been proved to be generally effective in a varietyw xof conditions 1,2 and specifically during labor

w xand delivery 3,4 .Patients, who have used TENS for pain relief

w xduring labor, have expressed their satisfaction 4w xand no pathological FHR tracing 5 or adverse

w xeffects on the newborn have been noted 7 . Someauthors have also highlighted the beneficial TENS

w xin reducing the duration of labor 5 , but thisw xfinding has been negated by others 7 . The pre-

sent series is one of the largest studying TENSuse during labor. We evaluated the efficacy of anew TENS device, which was designed and con-structed in Israel according to our specificationsw x11 , based on our favorable experience with TENS

w x w xfor primary dysmenorrhea 9,10 . Others, 6 havealso examined the efficacy of a locally producedŽ .US-made design device. It should be empha-sized that the efficacy of the specific deviceŽ .Freemom, LifeCare, Israel rather than the

Ž .modality itself TENS was examined. The anal-gesic effect was also investigated both; subjec-tively, by self-report questionnaire and objec-tively, by different intrapartum and neonatal out-come parameters. Our study used similar tech-niques to those employed in earlier work studiesthat examined TENS use during labor and deliv-

w xery 4]10 .The fact that the women themselves elected

whether to participate in the study or not, as wellas the fact that multiparas, who have been ex-posed to other types of pain-control during labor,entered the study by their own free will and thefact that a considerable part of the participantseventually needed pain-relief therapy, all excludethe possibility of a selection bias. The majority ofparturients who used TENS, irrespective of their

obstetric history or previous use of pain relieversduring labor, found TENS effective for the man-agement of labor pain. Nevertheless, a consider-able proportion requested an adjuvant pain-reliefmethod later, during delivery. Apparently, thelabor pains intensified towards the second stageof labor, TENS was not sufficiently effective.Therefore the use of TENS may serve parturientsat the beginning of the first stage; those whorequested additional pain relief treatment did soat a later stage with significantly higher degreesof cervical dilatation, thereby minimizing the totalintake of potentially hazardous analgesic drugsw x5,12,16 .

The favorable potential of TENS on the onehand and the need for other types of pain-reliefon the other, may need further improvements inthe design of devices aimed specifically to cope

w xwith the quality of pain of labor 4 . Most parturi-ents, including multiparas who have been exposedto other methods of pain-relief during labor, ex-pressed a desire to use TENS again for their nextdelivery. TENS also significantly shortened theduration of labor.

Although we have described only the findingsrelevant to the first stage of labor, the same trendwas noted for the second stage as well. Theseresults were not incorporated here because thepossible prolongation of the second stage in thoseparturients who received an epidural block may

w xhere have biased the results 17 . A possible ex-planation for the second stage findings is thedecrease in maternal discomfort and anxiety af-forded by TENS pain relief, which was achievedimmediately on admission to the delivery room.TENS decreases catecholamine release because

w xthe epinephrine inhibits uterine activity 12 .Therefore the alleviation of pain obtained byTENS may have a beneficial effect on the progress

w xof labor as well 12 . Indeed, 33% of the nulli-paras and 40% of the multiparas completed laborand delivery using only TENS for the manage-ment of pain.

Apart from being non-pharmacologic and non-invasive, TENS has proven to be cost-effective.The purchase price of the device is approximatelyUS$100 and operating costs are minimal. By con-trast, the price of one dose of analgesics

( )B. Kaplan et al. r International Journal of Gynecology & Obstetrics 60 1998 251]255 255

Ž .meperidineqpromethazine is US$1 and two tothree doses are required during normal labor.Assuming 3000 annual deliveries and taking intoaccount that TENS can reduce analgesic con-

w xsumption by one-third 5 , the use of six TENSdevices in our six delivery rooms yields consider-able savings.

In conclusion, the Freemom TENS model hasproven beneficial for pain relief during labor andhas no adverse effect on mother or newborn. Webelieve that the use of this modality should beexpanded so that clinicians might gain more expe-rience with it and more parturients can benefitfrom it.

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