Elsevier

Midwifery

Volume 27, Issue 4, August 2011, Pages 547-552
Midwifery

Hi-TENS combined with PCA-morphine as post caesarean pain relief

https://doi.org/10.1016/j.midw.2010.05.002Get rights and content

Abstract

Objectives

to examine effectiveness and overall opiate consumption between high-sensory transcutaneous electrical nerve stimulation (Hi-TENS) combined with patient-controlled analgesia with morphine and patient-controlled analgesia with morphine alone following elective (e.g. scheduled) caesarean birth.

Design

randomised, controlled study.

Setting

a county hospital in south-west Sweden.

Participants

42 multiparous women.

Measurements and findings

participants were randomly assigned and connected to patient-controlled analgesia with morphine alone or in combination with Hi-TENS apparatus. Levels of morphine consumed were calculated every third hour during the first 24 hours post partum. Pain and sedation were assessed by visual analogue scale at one, three, six, nine, 12 and 24 hours post partum. Total consumption of morphine differed significantly between the groups: morphine with TENS was 16.2±12.6 mg and morphine alone was 33.1±20.9 mg (p=0.007). Assessment of pain relief showed no significant difference. Sedation differed significantly between the groups (p=0.045), especially between three and 12 hours post partum (p=0.011).

Key conclusions and implications for practice

pain relief from a combination of Hi-TENS and patient-controlled analgesia with morphine was as effective as patient-controlled analgesia with morphine alone, produced less sedation and reduced morphine use by approximately 50%. Women undergoing a caesarean section should be given the opportunity to make an informed choice about post operative pain relief before surgery. A presumed benefit of this treatment combination is that the mother is more alert and better able to interact with her newborn during the first hours after birth without drowsiness due to large doses of opiates.

Introduction

High levels of pain during the first 24 hours following caesarean birth have recently been reported (Karlström et al., 2007). Efforts to manage acute post operative pain have long been under investigation and in clinical practice. However, prior to the use of patient-controlled therapies, post caesarean mothers were less likely to receive adequate relief from as-needed analgesia therapies when administered by care providers who underestimated the mother’s level and intensity of pain (Olden et al., 1995). Adequate pain relief following caesarean section might also include consideration that treatment outcome should avoid negatively influencing the well-being and alertness of the mother in order that she may freely interact with her newborn. A combination of methods may therefore be required so that the mother is free from pain without experiencing adverse, dose-dependent opiate side-effects such as significant respiratory depression, nausea, vomiting and sedation (Thompson et al., 1995, Gadsden et al., 2005).

Satisfactory pain relief from the use of intravenous patient-controlled analgesia (PCA) is well documented in the literature (Sia and Chong, 1999, D'Angelo, 2003, Halpern et al., 2004), and this method has subsequently become commonly available as acute pain relief therapy following caesarean section. Mothers may additionally gain a more enhanced sense of control over their post operative pain by using PCA (Perry et al., 1994, MacIntyre, 2001, Hudcova et al., 2006). Comparison between PCA and the use of intramuscular (IM) injection shows increased effectiveness for PCA, as optimal levels of the analgesic can be maintained and may therefore eliminate the uneven and unpredictable absorption rates seen after IM injection (Jackson, 1989). Further, a study examining PCA versus continuous epidural infusion for pain relief showed that PCA is more commonly reported to demonstrate lower nausea/vomiting and no motor block (Wu et al., 2005).

The type of opiate used with PCA seems to be important if this method is to be considered optimal. A study exploring pain relief among patients undergoing major abdominal surgery compared PCA with morphine and PCA with meperidine (pethedine HCl; Demerol, Sanofi-Aventis, USA), and found enhanced pain relief with less sedation, improved motor co-ordination and less maternal dysphoria in the morphine group (Plummer et al., 1997). Additionally, preference for the use of morphine is supported by reports observing less sedation in newborn breast-feeding infants (Wittels et al., 1990) and less interruption of breast feeding, as well as significantly higher levels of rooming-in (Yost et al., 2004).

Non-opiate forms of pain relief have also been demonstrated empirically. These methods include vibration techniques, transcutaneous electrical nerve stimulation (TENS), acupuncture and various massage techniques, such as tactile massage (Melzack et al., 1983, Rittweger et al., 2002, van Tulder et al., 2005). TENS is used to stimulate the skin in order to increase production of endogenous opiates, and at certain frequencies is also understood to activate opioid receptors in the brain and spinal cord, which then increases blockage of painful stimuli by seratonergic pathways innervating the spinal dorsal horn (Wall and Sweet, 1967, Sluka et al., 1999, Sluka et al., 2009, Kalra et al., 2001). The TENS apparatus is offered in an intensity range between high frequency (>50 Hz; Hi-TENS) and low frequency (<10 Hz; Lo-TENS), and in general has yielded varying effects. However, when used alone, the apparatus has been shown to produce a satisfactory post-operative analgesia after caesarean section (Ledergerber, 1978, Hollinger, 1986, Smith et al., 1986, Van der Spank et al., 2000).

In practice, pain management following caesarean section would best incorporate knowledge about patient outcomes, with particular regard to self-reported pain intensity and severity (Chung and Liu, 2003). The level of pain, as recorded at the moment it is occurring, further offers an essential component to identifying the quality of pain experienced (Erskine et al., 1990). Such information is especially important in patient-centred care, which would opt to provide women with informed choice about their post caesarean pain relief. In consideration of these elements, the present study aimed to contribute to the growing literature on effective post caesarean pain management. Current levels of post caesarean pain and sedation over the first 24 hours after birth were identified by comparing PCA with morphine alone (PCA-m) and a combination of sensory-level Hi-TENS and PCA with morphine (PCA-TENS). Overall consumption of morphine was assessed.

Section snippets

Methods

The study was conducted in a county hospital in South-west Sweden in 2001–2003, and is part of a larger study investigating the effects of morphine levels on hormonal and behavioural adaptations following caesarean section. Background information about socio-demographic and obstetric data was collected from the birth records and from a background questionnaire prepared for this specific investigation.

Background data

Socio-economic data, age, years of education, civil status, smoking status, parity and attended parenting classes were gathered as background data. The median age for women in both groups was 33 years, and interquartile ranges varied from 27 to 37 years for the PCA-TENS group and 29–35 years for the PCA group. All women in both groups were either married or lived together with the father of the infant. Four of 22 women smoked in the PCA-TENS group; the corresponding number for the PCA group was

Discussion

This paper has compared methods incorporating morphine use in post operative caesarean women who received either PCA-morphine alone or PCA-morphine supported with TENS. A limitation of this study was that the observer was not blind to the different treatments, as the study design did not control for a blind usage of the TENS apparatus. To blind the usage of an already known device is difficult, if not impossible; however, it has been suggested that studies not fully blinded may exaggerate the

Conflict of interest statement

The authors declare no competing interests.

Acknowledgements

Annica Gustafsson initiated this study but sadly passed away during analyses and writing. The authors wish to thank Ann-Sofi Matthiesen for statistical assistance. The authors gratefully acknowledge the women who participated in this project, as well as financial support from the Skaraborg Institute for Research and Development, the Scientific Committee at Central Hospital, Skövde, Sweden, the Foundation for the Masonic Orphanage in Stockholm (Stiftelsen Frimurare Barnhuset) and the Swedish

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