Lack of analgesic effect of systemically administered morphine or pethidine on labour pain

Meperidine Compared With Nitrous Oxide for Intrapartum Pain Relief in Multiparous Patients: A Randomized Controlled Trial

OBJECTIVE

To compare the efficacy and adverse effects of intravenous meperidine and inhaled nitrous oxide for intrapartum analgesia in multiparous patients.

METHODS

This randomized controlled trial was conducted in the delivery ward of a university teaching medical center in Afula, Israel. Multiparous patients with term, singleton pregnancies who were in labor were randomized in a 1:1 ratio to 50 mg intravenous meperidine or inhaled nitrous oxide. The primary outcome was pain intensity 20-30 minutes after analgesic administration, measured on a visual analog scale (VAS) from 0 to 10 cm. Secondary outcomes included the need for additional analgesia, labor length, delivery mode, patient satisfaction, and maternal and neonatal adverse effects. To detect a 1-cm (±2.6) difference in VAS score between the groups, 214 total participants were needed to achieve 80% power with an alpha of 0.05.

RESULTS

From August 2016 through May 2019, 214 participants were enrolled. Fourteen were excluded after randomization. Of the 200 analyzed, 102 received nitrous oxide, and 98 received intravenous meperidine. Demographic and obstetric variables were comparable between the two groups. The VAS score 20-30 minutes after analgesic administration did not differ between the groups (7.7±2.3 cm and 7.6±2.7 cm in the nitrous oxide and meperidine groups, respectively, P=.89). There were no significant differences between the groups in the rate of additional analgesic use, labor length, delivery mode, Apgar scores, rate of breastfeeding, patient satisfaction, or maternal and neonatal adverse effects.

CONCLUSION

Pain intensity was comparable in multiparous patients 20-30 minutes after administration of meperidine and nitrous oxide. Adverse effects were also comparable.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02783508.

Sterile water injections for relief of labour pain (the SATURN trial): study protocol for a randomised controlled trial

Background

Up to 80% of women use some form of pharmacological analgesia during labour and birth. The side effects of pharmacological agents are often incompatible with the concurrent use of non-pharmacological pain relieving strategies, such as water immersion, ambulation and upright positioning, or may have negative effects on both the mother and fetus. Sterile water injections given into the skin of the lumbar region have been demonstrated to reduce back pain during labour. However, the injections given for back pain have no effect on abdominal contraction pain. The analgesic efficacy of sterile water injections for abdominal pain during childbirth is unknown. The injections cause an immediate, brief but significant pain that deters some women from using the procedure. This study aims to investigate the use of water injections given intradermally into the abdomen to relieve labour contraction pain. A vapocoolant spray will be applied to the skin immediately prior to the injections to reduce the injection pain.

Methods

In this pragmatic, placebo controlled trial 154 low-risk women in labour at term with a labour pain score ≥ 60 on a 100 millimitre visual analogue scale (VAS) will be randomly allocated to receive either six injections of sterile water or a sodium chloride 0.9% solution as a placebo (0.1–.0.3 ml per injection). Three injections are given along the midline from the fundus to the supra-pubis and three laterally across the supra-pubis. The primary outcome will be the difference in VAS score 30 min post injection between groups. Secondary outcomes include VAS score of the injection pain on administration, VAS score of labour pain at 60 and 90 min, maternal and neonatal birth outcomes.

Discussion

Access to effective pain relief during labour is fundamental to respectful and safe maternity care. Pharmacological analgesics should support rather than limit other non-pharmacological strategies. Sterile water injections have the potential to provide an alternative form of labour pain relief that is easy to administer in any labour and birth setting, and compatible with other non-pharmacological choices.

Trial registration

ANZCTR (ACTRN12621001036808) Date submitted: 22/06/2021. Date registered: 05/08/2021. https://www.anzctr.org.au/

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06093-3.

Involvement of the nociceptin opioid peptide receptor in morphine-induced antinociception, tolerance and physical dependence in female mice

Nociceptin opioid peptide (NOP) receptor modulates pain transmission and is considered a prospective target for pain management. Under acute pain conditions in rodents, however, no definitive conclusions about effects of systemically intervening NOP receptors on nociception, classical opioid-induced antinociception, tolerance and physical dependence have been drawn. Given that opioid analgesia has sex differences, and females experience greater pain and consume more opioids, clarifying these issues in females will help develop novel analgesics. To clarify the role of NOP receptors on the pharmacological profiles of µ-opioid receptor agonists, in this study, a selective agonist (SCH221510) and antagonist (SB612111) of the NOP receptor were subcutaneously administered in female mice in multiple animal models. In hot-plate test, neither SCH221510 (3 and 10 mg/kg, sc) nor SB612111 (10 mg/kg, sc) produced significant antinociception. SCH221510 (3 mg/kg, sc) attenuated but SB612111 (10 mg/kg, sc) enhanced morphine-induced antinociception, with rightward and leftward shift of morphine dose-response curves, respectively. SCH221510 (3 mg/kg, sc) combined with morphine (10 mg/kg, sc) accelerated the development of morphine antinociceptive tolerance. Conversely, SB612111 (10 mg/kg, sc) delayed morphine tolerance development. Neither SCH221510 (3 mg/kg, sc) nor SB612111 (10 mg/kg, sc) statistically significantly altered the development of morphine-induced physical dependence. Therefore, systemic activation of NOP receptors attenuated morphine antinociception to acute thermal stimuli, facilitated morphine-induced antinociceptive tolerance but did not robustly alter physical dependence in female mice. Systemic blockade of NOP receptors produced opposite actions. These findings demonstrate that N/OFQ-NOP receptor system plays diverse roles in modulating pharmacological profiles of µ-opioid receptor agonists.

Parturition in Mammals: Animal Models, Pain and Distress

Parturition is a complex physiological process and involves many hormonal, morphological, physiological, and behavioural changes. Labour is a crucial moment for numerous species and is usually the most painful experience in females. Contrary to the extensive research in humans, there are limited pain studies associated with the birth process in domestic animals. Nonetheless, awareness of parturition has increased among the public, owners, and the scientific community during recent years. Dystocia is a significant factor that increases the level of parturition pain. It is considered less common in polytocous species because newborns' number and small size might lead to the belief that the parturition process is less painful than in monotocous animal species and humans. This review aims to provide elements of the current knowledge about human labour pain (monotocous species), the relevant contribution of the rat model to human labour pain, and the current clinical and experimental knowledge of parturition pain mechanisms in domestic animals that support the fact that domestic polytocous species also experience pain. Moreover, both for women and domestic animal species, parturition's pain represents a potential welfare concern, and information on pain indicators and the appropriate analgesic therapy are discussed.

The Effect of Pethidine Analgesia on Labor Duration and Maternal-Fetal Outcomes

Background and Aim:

Opioid analgesics had been used from time to time for treating labor pain. However, their use have been concerning. The aim of this study is to evaluate the effect of pethidine on duration of active phase of labor, labor pain and maternal-neonatal outcomes.

Methods:

In the present case-control study, the study group received a 50 mg pethidine intramuscular injection upon the start of active phase of labor, and the control group consisted of patients who receive placebo injeciton. In both groups, vital signs were measured before, and at 0, 5, 15, 30, 45 and 60 minutes after the injection. Pain intensity was evaluated with Visual Analogue Scale (VAS) prior to, and 1 hour and 2 hours after injection. Data regarding labor phase durations, maternal side effects, newborn APGAR scores and fetal respiratory problems were recorded.

Results:

102 patients in Pethidine group and 92 patients in control group, were included into the study. Labor pain VAS-scores were significantly lower in the study group (p<0.001). Moreover, active phase of labor duration was significantly shorter in the study group (p<0.001). Maternal pulse significantly decreased, and maternal nausea-vomiting was frequent in the study groups. However, the groups were similar in terms of other side effects and neonatal outcomes.

Conclusions:

Pethidine significantly reduces active phase of labor duration, has a favorable analgesic effect in treating labor pain and is not associated with serious maternal or neonatal complications. It is therefore considered an acceptable agent for use during active phase of labor. (www.actabiomedica.it)

Comparison of Pain Score and Complications Following Acetaminophen and Pethidine Injection During Vaginal Delivery: A Double-blind Clinical Trial

Objectives

Recently, intravenous acetaminophen has been introduced as an intervention with analgesic potential similar to that of opioid analgesics in labor pain management. This study aimed to compare the pain score and maternal and neonatal complications following acetaminophen and pethidine injections during vaginal delivery.

Methods

This randomized, double-blind clinical trial was conducted on pregnant women during the first stage of delivery referred to Ghaem and Omolbanin Hospitals in Mashhad, Iran, from March to December 2017. The subjects were assigned randomly to one of two groups: acetaminophen and pethidine. The pain intensity was measured before and 15, 60, 120, 180, and 240 minutes after injection.

Results

The pain score and pain score changes showed no significant difference between the two groups at different times. The incidence of maternal complications during delivery and the first hour after delivery was not statistically significant between the two groups, but 15 minutes after injection, vomiting (p = 0.001), nausea (p = 0.001), and dizziness (p = 0.001) were significantly higher in the pethidine group. The mean one and five minutes Apgar scores were significantly higher in the acetaminophen group.

Conclusions

Intravenous acetaminophen led to fewer maternal complications than pethidine, especially during the first 15 minutes after injection and fewer neonatal complications, especially in the Apgar score.

[Effects of Obstetric Analgesia with Systemic Opioids on the Newborn - A Review]

INTRODUCTION

Three-quarters of all women receive analgesia during labor. There are regional and systemic analgesia procedures available. In this review, we investigate the impact of obstetric analgesia using systemic opioids on neonatal outcomes.

METHODS

We searched the PubMed and Cochrane Library databases using the following search terms: "meptazinol", "meptide", "analgesia", "painkiller", "pain reliever", "obstetrics", "labor", "labour", "delivery", "neonate", "newborn", "child", "baby", "infant", "fetus", "fetal", "opioid" and "opiate" as well as performed an additional MeSH Terms search in PubMed.

RESULTS

Of 355 potentially relevant studies, we included 23 studies in this review. The studies varied widely in quality, sample size, and outcome criteria. Neonatal outcome was often only a secondary endpoint. Rarely were significant differences related to neonatal outcome reported between the different systemic opioids or compared with control groups. Twelve studies compared neonatal APGAR scores between treatment groups, with ten (83%) of these studies showing no differences.

DISCUSSION/OUTLOOK

In summary, we assess the evidence as limited and ambiguous as to whether systemic obstetric opioid therapy negatively affects the newborn. Studies regarding the long-term outcome of the newborns are lacking. A statement regarding the necessity of postnatal monitoring of newborns after maternal obstetric opioid therapy cannot be concluded. Further studies, ideally with a prospective study design and control group, should be considered.

Sex differences in pain and opioid mediated antinociception: Modulatory role of gonadal hormones

Sex-related differences in pain and opioids has been the focus of many researches. It is demonstrated that women experience greater clinical pain, lower pain threshold and tolerance, more sensitivity and distress to experimentally induced pain compared to men. Sex differences in response to opioid treatment revealed inconsistent results. However, the etiology of these disparities is not fully elucidated. It is, therefore, conceivable now that this literature merits to be revisited comprehensively. Possible multifaceted factors seem to be associated. These include neuroanatomical, hormonal, neuroimmunological, psychological, social and cultural aspects and comorbidities. This review aims at providing an overview of the substantial literature documenting the sex differences in pain and analgesic response to opioids from animal and human studies within the context of the modulatory effects of the aforementioned factors. A detailed and critical discussion of the cellular and molecular signaling pathways underlying the modulatory actions of gonadal hormones in the sexual dimorphism in pain processing and opioid analgesia is extensively presented. It is indicated that sexual dimorphic activation of certain brain regions contributes to differential pain sensitivity between females and males. Plausible crosstalk between sex hormones and neuroimmunological signaling pertinent to toll-like and purinergic receptors is uncovered as causal cues underlying sexually dimorphic pain and opioid analgesia. Conceivably, a thorough understanding of these factors may aid in sex-related advancement in pain therapeutic management.

Parenteral opioids for maternal pain management in labour

BACKGROUND

Parenteral opioids (intramuscular and intravenous drugs including patient-controlled analgesia) are used for pain relief in labour in many countries throughout the world. This review is an update of a review first published in 2010.

OBJECTIVES

To assess the effectiveness, safety and acceptability to women of different types, doses and modes of administration of parenteral opioid analgesia in labour. A second objective is to assess the effects of opioids in labour on the baby in terms of safety, condition at birth and early feeding.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (11 May 2017) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining the use of intramuscular or intravenous opioids (including patient-controlled analgesia) for women in labour. Cluster-randomised trials were also eligible for inclusion, although none were identified. We did not include quasi-randomised trials. We looked at studies comparing an opioid with another opioid, placebo, no treatment, other non-pharmacological interventions (transcutaneous electrical nerve stimulation (TENS)) or inhaled analgesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the quality of each evidence synthesis using the GRADE approach.

MAIN RESULTS

We included 70 studies that compared an opioid with placebo or no treatment, another opioid administered intramuscularly or intravenously or compared with TENS applied to the back. Sixty-one studies involving more than 8000 women contributed data to the review and these studies reported on 34 different comparisons; for many comparisons and outcomes only one study contributed data. All of the studies were conducted in hospital settings, on healthy women with uncomplicated pregnancies at 37 to 42 weeks' gestation. We excluded studies focusing on women with pre-eclampsia or pre-existing conditions or with a compromised fetus. Overall, the evidence was graded as low- or very low-quality regarding the analgesic effect of opioids and satisfaction with analgesia; evidence was downgraded because of study design limitations, and many of the studies were underpowered to detect differences between groups and so effect estimates were imprecise. Due to the large number of different comparisons, it was not possible to present GRADE findings for every comparison.For the comparison of intramuscular pethidine (50 mg/100 mg) versus placebo, no clear differences were found in maternal satisfaction with analgesia measured during labour (number of women satisfied or very satisfied after 30 minutes: 50 women; 1 trial; risk ratio (RR) 7.00, 95% confidence interval (CI) 0.38 to 128.87, very low-quality evidence), or number of women requesting an epidural (50 women; 1 trial; RR 0.50, 95% CI 0.14 to 1.78; very low-quality evidence). Pain scores (reduction in visual analogue scale (VAS) score of at least 40 mm: 50 women; 1 trial; RR 25, 95% CI 1.56 to 400, low-quality evidence) and pain measured in labour (women reporting pain relief to be "good" or "fair" within one hour of administration: 116 women; 1 trial; RR 1.75, 95% CI 1.24 to 2.47, low-quality evidence) were both reduced in the pethidine group, and fewer women requested any additional analgesia (50 women; 1 trial; RR 0.71, 95% CI 0.54 to 0.94, low-quality evidence).There was limited information on adverse effects and harm to women and babies. There were few results that clearly showed that one opioid was more effective than another. Overall, findings indicated that parenteral opioids provided some pain relief and moderate satisfaction with analgesia in labour. Opioid drugs were associated with maternal nausea, vomiting and drowsiness, although different opioid drugs were associated with different adverse effects. There was no clear evidence of adverse effects of opioids on the newborn. We did not have sufficient evidence to assess which opioid drug provided the best pain relief with the least adverse effects.

AUTHORS' CONCLUSIONS

Though most evidence is of low- or very-low quality, for healthy women with an uncomplicated pregnancy who are giving birth at 37 to 42 weeks, parenteral opioids appear to provide some relief from pain in labour but are associated with drowsiness, nausea, and vomiting in the woman. Effects on the newborn are unclear. Maternal satisfaction with opioid analgesia was largely unreported. The review needs to be examined alongside related Cochrane reviews. More research is needed to determine which analgesic intervention is most effective, and provides greatest satisfaction to women with acceptable adverse effects for mothers and their newborn.

Should Nitrous Oxide Be Used for Laboring Patients?

Nitrous oxide, long used during labor in Europe, is gaining popularity in the United States. It offers many beneficial attributes, with few drawbacks. Cost, safety, and side effect profiles are favorable. Analgesic effectiveness is highly variable, yet maternal satisfaction is often high among the women who choose to use it. Despite being less effective in treating labor pain than neuraxial analgesic modalities, nitrous oxide serves the needs and preferences of a subset of laboring parturients. Nitrous oxide should, therefore, be considered for inclusion in the repertoire of modalities used to alleviate pain and facilitate effective coping during labor.

A Randomized Controlled Trial Comparing Use of Enthonox With Pethidine for Pain Relief in Primigravid Women During the Active Phase of Labor

Background

The use of pain-relieving drugs during labor is now part of standard care in many countries throughout the world. Each method of pain relief has its own risks and benefits, variations in effectiveness, and availability and acceptability.

Objectives

This study aimed to assess the efficacy and safety of intramuscular pethidine as an analgesic during labor by comparing it to inhaled 50% nitrous oxide (Entonox).

Methods

In this clinical trial study, 100 women who expected to have a natural childbirth were observed. The inclusion criteria for this study were the commencement of spontaneous labor pain along with appropriate maternal and fetal indications for vaginal delivery. By using random numbers, each subject was randomly allocated to one of two groups, with one group using Entonox and the other receiving an intramuscular injection of 0.5 mg/kg of pethidine for pain relief. The intensity of labor pain experienced by the subjects and the outcomes of the deliveries were collected with questionnaires.

Results

The average pain scores in the Entonox and pethidine groups were 3.94 ± 1.4 and 5.6 ± 1.1, respectively, 30 minutes after intervention (P = 0.001), but there was not a significant difference in the severity of the pain (5.06 ± 1.4 and 4.7 ± 1.1 for the Entonox and pethidine groups, respectively) between the subjects in each group 60 minutes after the intervention (P = 0.592). No significant differences were seen in the duration and interval of uterine contractions, maternal complications, Apgar scores, and the duration of the first and second stage of labor between the two studied groups (P > 0.05). An analysis of the pooled risk differences showed that none of the side effects investigated were significantly different between the two groups except for mouth dryness, which was significantly higher in nitrous oxide users (P = 0.044).

Conclusions

Inhaled nitrous oxide seems to give better pain relief in the short term compared to a single dose of pethidine. Entonox, which is more convenient to administer than an intramuscular injection of pethidine, is also regarded as safe both for mothers and neonates.

Paracervical block as pain treatment during second-trimester medical termination of pregnancy: an RCT with bupivacaine versus sodium chloride

STUDY QUESTION

Can paracervical block (PCB) administered before the onset of pain decrease women's pain experience during second-trimester medical termination of pregnancy (MToP)?

SUMMARY ANSWER

There were no clinically significant differences between groups receiving PCB with bupivacaine or saline with regard to the highest and lowest pain intensity, morphine consumption or induction-to abortion interval.

WHAT IS KNOWN ALREADY

The most common side effect of misoprostol is pain; nevertheless, there are sparse studies in pain and pain treatment during MToP, especially in second-trimester abortion. Pain reported in second-trimester medical abortion is often intense, and peaks when the fetal expulsion occurs.

STUDY DESIGN, SIZE, DURATION

A double-blinded RCT was carried out from May 2012 until April 2015. A power calculation was based on a previous pilot study showing that the proportion of women with severe pain [visual analogue scale (VAS) ≥7] was 63%. A clinically significant reduction was considered to yield 35% with severe pain, and with a power of 80% and significance level of 5% (two-sided) 112 women were needed. Accounting for a 20% drop-out rate, a total of 140 women were needed. The primary outcome, pain intensity measured as any VAS ≥7, was analysed using a generalized estimating equations model. The level of significance was set to P < 0.05 two-sided. A computer generated randomization list with block size of 10 was used. The treatment allocation was placed in a sealed, opaque, envelope and picked consecutively.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 589 women attending a gynaecological clinic had a second-trimester abortion during the study period and 276 were invited to participate. A total of 113 women undergoing abortion from 13 weeks of gestation and above were recruited, of which 55 were randomly allocated to receive a PCB with bupivacaine and 58 a PCB with sodium chloride 1 h after the first dose of misoprostol. The full analysis set (FAS) population was defined as all randomized women that had at least one value for any of the outcomes (n = 102). The per-protocol (PP) population was defined as a subset of the FAS excluding patients with major protocol deviations or without a value for the primary outcome (n = 99). Pain was measured by VAS at misoprostol initiation (baseline) and repeated every 30 min until fetal expulsion. The primary outcome was the highest VAS pain intensity at any time point.

MAIN RESULTS AND THE ROLE OF CHANCE

The highest pain intensity, did not show any differences at a cut-off of VAS ≥7 [risk ratio (RR): 1.1; 95% confidence interval (CI): 0.9-1.5; P = 0.0.292]. In the PP analyses, there were 75% women in the bupivacaine group and 64% in the sodium chloride group with VAS ≥7 (RR: 1.2; 95% CI: 0.9-1.5; P = 0.235). Most women did not experience pain at the misoprostol start, 19 women scored a VAS of >0, ranging from 1 to 4 with a mean of 1.8 and median of 2 (P = 1.000). Immediately prior to PCB, 61 women scored a VAS of >0, from 1 to 10 with a mean of 2.0 and median of 1 (P = 0.771). There was a 48% loss of VAS scores at the time of expulsion and the remaining scores did not differ between groups (RR: 1.5; 95% CI: 0.9-2.5). A subgroup analysis of primipara did not show any difference in highest pain intensity VAS ≥7 (RR: 1.2; 95% CI: 0.9-1.6; P = 0.283). No statistically significant differences were observed between groups with regard to the highest and lowest (P = 553 and 0.182) pain intensity and morphine consumption (P = 0.772). Side effects were reported by 28 women (14 women in each group), with no differences between groups. Most common was nausea and vomiting in connection to morphine injection.

LIMITATIONS, REASONS FOR CAUTION

Nearly 60% of the invited women did not want to participate in the study (fear of needles and fear of receiving the placebo) therefore women who tolerate pain may have been overrepresented in the study population. Data collection was stopped, in error, when 113 participants had been recruited. The loss to follow-up was, however, only 11 women (10%), which was lower than expected but intrinsically the study did not fully reach the intended number of women, which may have influenced the results. In addition, the obstetrical and gynaecological background of participating women differs. The participants were informed that they had a 50% chance of receiving a PCB with active substance, which could theoretically have affected their expectations and pain experience (placebo effect). The frequent attention at VAS scoring and the overall care provided may also have affected the participants in a positive way, and helped women to feel supported and more relaxed during the abortion.

WIDER IMPLICATIONS OF THE FINDINGS

The highest pain intensity was severe (VAS: 7-10) among 65-75% of the participants, as reported for first-trimester medical abortion; however, the maximal pain scores remain high despite the PCB. There is, therefore, a clear need for more optimal pain treatment but only limited data exist on pain treatment during MToP over all gestational lengths. As PCB was well tolerated, did not cause any serious side effects and had no negative impact on the abortion process and efficacy, another approach may be worth exploring, namely PCB given on demand at the onset of painful contractions.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by grants from the Swedish Research Council (grant no: 2012-2844), ALF (Karolinska Institutet - Stockholm County Council, Agreement on Medical Research and Training) funding, the Karolinska Institutet, Stockholm South General Hospital, and Swedish Nurses in the Area of Pain - SSOS together with GlaxoSmithKline. None of the authors have any conflicts of interest.

TRIAL REGISTRATION NUMBER

The trial was registered with ClinicalTrials.gov (identifier: NCT01617564) and The EudraCT (number: 2010-020780-21) and was approved by The Regional Ethical Review Board at Karolinska Institutet (dnr: 2007/1277-31/2 and 2010/410-31/1).

TRIAL REGISTRATION DATE

Clinical trial registration was done in May 2012 before initiation of patient recruitment.

DATE OF FIRST PATIENT'S ENROLMENT

29 May 2012.

Intravenous paracetamol versus intramuscular pethidine in relief of labour pain in primigravid women

BACKGROUND

Intramuscular pethidine is one of most common opioids used for labour analgesia. There are a number of concerns in the literature regarding the use of pethidine. The aim of this study is to compare analgesic efficacy of paracetamol with pethidine for labour pain in normal vaginal delivery.

MATERIALS AND METHODS

In this single-blinded, randomised control trial, 80 primigravid singleton women with full-term pregnancy candidate for normal vaginal delivery, were entered the trial and divided in to pethidine (A) and paracetamol (B) groups. At the time of admission, age and body mass index of mother and gestational age based on last day of period were recorded. In both groups, intravenous promethazine and hyoscine were administered to each patient at the first stage of delivery. From beginning of active phase of delivery, patients in group A received 50 mg intramuscular pethidine injection. At the same time patients in group B, received an intravenous solution infusion containing 1000 mg paracetamol and 300 cc of normal saline. After child birth, average labour pain was assessed using Visual Analogue Scale (VAS) by direct questioning from patient in both groups.

RESULTS

After patients' selection, 19 individual omitted during study due to exclusion criteria and finally 30 patients in paracetamol group and 31 patients in pethidine group remained to enter the trial. There was no significant difference in age and BMI of mothers between both groups (P > 0.05). Maternal age and labour duration in paracetamol group had no meaningful difference with maternal age and labour duration of patients in pethidine group (P > 0.05). The average VAS pain score was significantly lower in paracetamol comparing to that of pethidine group (8.366 out of 10, 9.612 out of 10, respectively, P < 0.001).

CONCLUSION

It is concluded that intravenous paracetamol is more effective than intramuscular pethidine to relief labour pain in normal vaginal delivery.

Patient-Controlled Remifentanil Analgesia as Alternative for Pethidine with Midazolam During Oocyte Retrieval in IVF/ICSI Procedures: A Randomized Controlled Trial

BACKGROUND

Pethidine with midazolam-induced conscious sedation for pain relief during transvaginal oocyte retrieval for in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) procedures is associated with residual pain and oversedation. Patient-controlled analgesia (PCA) with remifentanil may serve as an alternative for pethidine. We investigated whether PCA remifentanil with diclofenac was associated with improved periprocedural pain relief than pethidine analgesia during IVF/ICSI procedures, with sedation scores, safety profiles, and patient satisfaction as secondary endpoints.

METHODS

Seventy-six women were randomized to receive pethidine (2 mg/kg i.m.) and midazolam (7.5 mg)-induced conscious sedation (n = 40) or PCA with remifentanil and diclofenac (50 mg; n = 36). The Numeric Rating Scale, McGill Pain Questionnaire (MPQ), Ramsey Sedation Scale, and a 5-day pain-and-discomfort diary were used to evaluate pain and sedation levels.

RESULTS

There were no differences in baseline characteristics and reproductive outcomes between both groups. Periprocedural pain scores were comparable for remifentanil and pethidine groups (4 [3 to 7] vs. 6 [4 to 8]; P = 0.13). Pain scores in the pethidine group were significantly lower at 30 minutes after the procedure (1 [0 to 3] vs. 2 [1 to 5]; P = 0.016), but at cost of higher sedation levels when compared to remifentanil (4 [2 to 4] vs. 2 [2 to 2]; P < 0.001). Patient satisfaction was higher, and MPQ scores were lower in the remifentanil group. There were no differences in safety profiles between both analgesics.

CONCLUSIONS

Patient-controlled analgesia with remifentanil showed a similar reduction in pain scores than pethidine with midazolam during oocyte retrieval, while pethidine induced the highest pain relief after the procedure. However, PCA remifentanil was associated with less sedation and a better patient satisfaction profile than pethidine.

Analgesia for childbirth: modern insights into an age-old challenge and the quest for an ideal approach

SUMMARY It is widely recognized that childbirth may be the most painful experience in a woman’s lifetime and that women have a right to relief. There are many options, but the efficacy of only a few is supported by robust evidence. Many influences determine which method of pain relief is chosen, including social and cultural factors, availability, cost and personal preference. Due to human diversity and the differing perspectives of consumers, obstetric care providers and health administrators, there is no such thing as ‘an ideal approach’. In resource-rich societies, major advances in parturient safety and outcome flow from technique development and better monitoring. Greater awareness of the negative impact of untreated pain and of the relevance of genetic, cultural and social factors motivates research into better predictive models, novel therapies and optimization of existing methods.

Must we press on until a young mother dies? Remifentanil patient controlled analgesia in labour may not be suited as a "poor man's epidural"

BACKGROUND

The epidural route is still considered the gold standard for labour analgesia, although it is not without serious consequences when incorrect placement goes unrecognized, e.g. in case of intravascular, intrathecal and subdural placements. Until now there has not been a viable alternative to epidural analgesia especially in view of the neonatal outcome and the need for respiratory support when long-acting opioids are used via the parenteral route. Pethidine and meptazinol are far from ideal having been described as providing rather sedation than analgesia, affecting the cardiotocograph (CTG), causing fetal acidosis and having active metabolites with prolonged half-lives especially in the neonate. Despite these obvious shortcomings, intramuscular and intravenously administered pethidine and comparable substances are still frequently used in delivery units. Since the end of the 90 ths remifentanil administered in a patient-controlled mode (PCA) had been reported as a useful alternative for labour analgesia in those women who either don't want, can't have or don't need epidural analgesia.

DISCUSSION

In view of the need for conversion to central neuraxial blocks and the analgesic effect remifentanil has been demonstrated to be superior to pethidine. Despite being less effective in terms of the resulting pain scores, clinical studies suggest that the satisfaction with analgesia may be comparable to that obtained with epidural analgesia. Owing to this fact, remifentanil has gained a place in modern labour analgesia in many institutions. However, the fact that remifentanil may cause harm should not be forgotten when the use of this potent mu-agonist is considered for the use in labouring women. In the setting of one-to-one midwifery care, appropriate monitoring and providing that enough experience exists with this potent opioid and the treatment of potential complications, remifentanil PCA is a useful option in addition to epidural analgesia and other central neuraxial blocks. Already described serious consequences should remind us not refer to remifentanil PCA as a "poor man's epidural" and to safely administer remifentanil with an appropriate indication.

SUMMARY

Therefore, the authors conclude that economic considerations and potential cost-savings in conjunction with remifentanil PCA may not be appropriate main endpoints when studying this valuable method for labour analgesia.

Efficacy and safety of remifentanil as an alternative labor analgesic

The objective of this review was to evaluate the clinical efficacy and safety of remifentanil in the management of labor pain. Although neuraxial analgesia is the best option during labor, alternative analgesic options are needed for patients with contraindications. Using a systematic literature search, clinical outcomes of remifentanil for labor pain have been summarized. Also, comparisons of remifentanil to other options including meperidine, epidural analgesia, fentanyl, and nitrous oxide are provided. Based on the literature review, remifentanil is associated with high overall maternal satisfaction and favorable side-effect profile. However, due to the low reporting of adverse events, large, randomized controlled trials are needed to evaluate maternal and neonatal safety adequately and determine the optimal dosing needed to provide effective analgesia. While remifentanil is a feasible alternative for patients who cannot or do not want to receive epidural analgesia, administration should be monitored closely for potential adverse effects.

Efficacy and side effects of intravenous remifentanil patient-controlled analgesia used in a stepwise approach for labour: an observational study

BACKGROUND

Remifentanil has a suitable pharmacological profile for labour analgesia. In this prospective, observational study, intravenous patient-controlled analgesia with remifentanil, using stepwise bolus doses without background infusion, was examined during the first and second stages of labour. Outcomes were pain reduction, maternal satisfaction, maternal and neonatal side effects and remifentanil metabolism in the neonate.

METHODS

Parturients with normal term singleton pregnancies were recruited. The initial remifentanil bolus dose was 0.15 μg/kg, increasing in steps of 0.15 μg/kg, with a 2-min lock-out. Pain scores using a 100 mm visual analogue scale, systolic and diastolic blood pressures, respiratory rate and maternal sedation were recorded every 15 min. Maternal oxygen saturation and heart rate were monitored continuously. Neonatal data included Apgar scores, clinical examination, naloxone use, resuscitation, umbilical cord blood gases and remifentanil concentrations.

RESULTS

Forty-one parturients were enrolled. Pain scores were significantly reduced in the first 3 h of patient-controlled analgesia use compared to baseline, and at the end of the first and second stages of labour (P<0.05). Maximal pain reduction was 60% (P<0.01). One patient had inadequate pain relief and converted to epidural analgesia. The mean highest dose of remifentanil was 0.7 μg/kg [range 0.3-1.05]. Ninety-three percent of patients were satisfied with their analgesia. The lowest oxygen saturation was 91% and the lowest respiratory rate was 9 breaths/min. Eleven parturients (27%) received supplemental oxygen due to oxygen saturations <92%. Maternal sedation was moderate, and neonatal data reassuring.

CONCLUSIONS

Remifentanil intravenous patient-controlled analgesia provides adequate pain relief and high maternal satisfaction during the first and second stages of labour. Maternal sedation and respiratory depression may occur, but no serious neonatal side effects were recorded. Careful monitoring is mandatory.

Remifentanil patient controlled analgesia versus epidural analgesia in labour. A multicentre randomized controlled trial

BACKGROUND

Pain relief during labour is a topic of major interest in the Netherlands. Epidural analgesia is considered to be the most effective method of pain relief and recommended as first choice. However its uptake by pregnant women is limited compared to other western countries, partly as a result of non-availability due to logistic problems. Remifentanil, a synthetic opioid, is very suitable for patient controlled analgesia. Recent studies show that epidural analgesia is superior to remifentanil patient controlled analgesia in terms of pain intensity score; however there was no difference in satisfaction with pain relief between both treatments.

METHODS/DESIGN

The proposed study is a multicentre randomized controlled study that assesses the cost-effectiveness of remifentanil patient controlled analgesia compared to epidural analgesia. We hypothesize that remifentanil patient controlled analgesia is as effective in improving pain appreciation scores as epidural analgesia, with lower costs and easier achievement of 24 hours availability of pain relief for women in labour and efficient pain relief for those with a contraindication for epidural analgesia.Eligible women will be informed about the study and randomized before active labour has started. Women will be randomly allocated to a strategy based on epidural analgesia or on remifentanil patient controlled analgesia when they request pain relief during labour. Primary outcome is the pain appreciation score, i.e. satisfaction with pain relief.Secondary outcome parameters are costs, patient satisfaction, pain scores (pain-intensity), mode of delivery and maternal and neonatal side effects.The economic analysis will be performed from a short-term healthcare perspective. For both strategies the cost of perinatal care for mother and child, starting at the onset of labour and ending ten days after delivery, will be registered and compared.

DISCUSSION

This study, considering cost effectiveness of remifentanil as first choice analgesia versus epidural analgesia, could strongly improve the care for 180.000 women, giving birth in the Netherlands yearly by giving them access to pain relief during labour, 24 hours a day.

TRIAL REGISTRATION NUMBER

Dutch Trial Register NTR2551, http://www.trialregister.nl.

Intravenous oxycodone for pain relief in the first stage of labour--maternal pharmacokinetics and neonatal exposure

Physiological changes during pregnancy may change pharmacokinetics of compounds. Oxycodone is an increasingly used opioid agonist in acute pain management but its pharmacokinetics in labouring women has not been established. We studied the maternal pharmacokinetics and neonatal exposure of intravenous oxycodone for pain relief in the first stage of labour. The study was prospective, open-labelled and with a control group. After informed consent, 15 nulliparous parturients and newborns, and newborns in a control group were studied. In the study group, oxycodone boluses of 1 mg i.v., up to a cumulative dose of 5 mg, was administered when labour pain score was 5/10 or higher. As the control group, 30 other newborns after uncomplicated deliveries with no systemic opioids were assessed for the neonatal outcome. In the study group, maternal pharmacokinetics of oxycodone was measured from plasma concentrations during labour, and neonatal exposure was assessed from umbilical plasma samples using population pharmacokinetic methods. Maternal plasma oxycodone concentration decreased with a median half-life of 2.6 hr (range, 1.8-2.8). Oxycodone concentrations in the umbilical plasma 2.7 μg/l (0.3-14.5) were similar as in maternal plasma 2.4 (0.1-14.8) μg/l at the time of birth. No severe or unexpected adverse effects were noted. To conclude, firstly, maternal elimination half-life of i.v. oxycodone was significantly shorter than that reported in non-pregnant women, and secondly, maternal plasma oxycodone at the birth correlated well with neonatal umbilical concentrations and may, thus, be used as an estimate of neonatal exposure.

Retrospective evaluation of intravenous fentanyl patient-controlled analgesia during labor

PURPOSE

Because the safety of intravenous fentanyl patient-controlled analgesia (iv-PCA) administered during labor remains unclear, we retrospectively examined the labor records from January 2005 to December 2007 in our institution, with a focus on both maternal and neonatal outcomes, as compared to no analgesia.

METHODS

Parturients over 35 weeks of gestational age who received fentanyl iv-PCA (iv-PCA group) or no analgesia (control group) during labor were enrolled. The former group received iv-PCA through a pump programmed to give a loading dose of 0.05 mg fentanyl, followed by bolus injection of 0.02 mg fentanyl, with a lock-out interval of 5 min. This analgesia was initiated at the parturient's request and was discontinued before the second stage of labor, to ensure neonatal safety. During labor, both maternal and fetal heart rates, maternal pulse oximeter oxygen saturation (SpO(2)), respiratory rate, and sedation and nausea scores were continuously monitored, and the neonatal outcomes including umbilical arterial pH, Apgar scores, and other parameters were recorded.

RESULTS

The data of 129 of the 143 parturients who received fentanyl iv-PCA were analyzed, while 697 parturients delivered without any analgesia during the 3-year study period. While iv-PCA prolonged the duration of labor and increased oxytocin use, no obvious maternal or neonatal complications of fentanyl use were recorded. Except for the significantly lower rate of emergency cesarean section in the iv-PCA group, both the maternal and neonatal outcomes were comparable between the groups.

CONCLUSIONS

As compared to no analgesia, fentanyl iv-PCA appears to be safe and clinically acceptable as analgesia during labor, particularly in nulliparous women.

Pain relief in labor: a survey of awareness, attitude, and practice of health care providers in Zaria, Nigeria

Background:

The purpose of this study was to assess the attitudes of maternal health care providers to pain relief during labor in Zaria, Nigeria.

Methods:

This was a multicenter, collaborative, cross-sectional pilot study of provider perspectives concerning pain relief during labor. A structured, self-administered, questionnaire was completed by 95 consenting maternal health care providers at three high-volume facilities in Zaria, an ancient northern Nigerian city. Descriptive statistics was performed on the data.

Results:

Most respondents (94.8%) agreed that pain relief is needed during labor. Only 2.1% of respondents were undecided about the provision of pain relief during labor and 3.2% were of the opinion that pain relief was not necessary during labor. Most respondents (93.7%) had attended a woman in labor in the 4 weeks preceding the survey. Of these, 56.8% had counseled a parturient in labor. Most of the counseling (42.1%) took place during labor. Less than half of the respondents (48.4%) had administered pain relief in labor in the preceding 4 weeks and systemic opioids was the most commonly form of pain relief. Among the respondents who did not offer pain relief agents in labor, the majority (54.5%) had no reason for not offering it. Unavailability of methods, inability to afford the cost of pain relief, lack of knowledge and skills, as well as lack of essential equipment to provide the procedure were also given by respondents as reasons for not offering pain relief.

Conclusion:

Even though maternal health care providers in this environment have a positive attitude to pain relief in labor, most women go through labor without the benefit of analgesia. There exists a gap between provider attitudes to pain relief in labor and practice of the same, with many providers having no genuine reason(s) for not offering pain relief to their clients during labor. Providers need to align their practice to their attitudes, and need to be helped to do this through training as well as enhancing their ability to think critically about their practice.

The IDvIP trial: a two-centre randomised double-blind controlled trial comparing intramuscular diamorphine and intramuscular pethidine for labour analgesia

Background

Intramuscular pethidine is routinely used throughout the UK for labour analgesia. Studies have suggested that pethidine provides little pain relief in labour and has a number of side effects affecting mother and neonate. It can cause nausea, vomiting and dysphoria in mothers and can cause reduced fetal heart rate variability and accelerations. Neonatal effects include respiratory depression and impaired feeding. There are few large studies comparing the relative side effects and efficacy of different opioids in labour. A small trial comparing intramuscular pethidine with diamorphine, showed diamorphine to have some benefits over pethidine when used for labour analgesia but the study did not investigate the adverse effects of either opioid.

Methods

The Intramuscular Diamorphine versus Intramuscular Pethidine (IDvIP) trial is a randomised double-blind two centre controlled trial comparing intramuscular diamorphine and pethidine regarding their analgesic efficacy in labour and their side effects in mother, fetus and neonate. Information about the trial will be provided to women in the antenatal period or in early labour. Consent and recruitment to the trial will be obtained when the mother requests opioid analgesia. The sample size requirement is 406 women with data on primary outcomes. The maternal primary outcomes are pain relief during the first 3 hours after trial analgesia and specifically pain relief after 60 minutes. The neonatal primary outcomes are need for resuscitation and Apgar Score <7 at 1 minute. The secondary outcomes are an additional measure of pain relief, maternal sedation, nausea and vomiting, maternal oxygen saturation, satisfaction with analgesia, whether method of analgesia would be used again, use of Entonox, umbilical arterial and venous pH, fetal heart rate, meconium staining, time from delivery to first breath, Apgar scores at 5 mins, naloxone requirement, transfer to neonatal intensive care unit, neonatal haemoglobin oxygen saturation at 30, 60, 90, and 120 mins after delivery, and neonatal sedation and feeding behaviour during first 2 hours.

Discussion

If the trial demonstrates that diamorphine provides better analgesia with fewer side effects in mother and neonate this could lead to a change in national practice and result in diamorphine becoming the preferred intramuscular opioid for analgesia in labour.

Trial Registration

ISRCTN14898678

Eudra No: 2006-003250-18, REC Reference No: 06/Q1702/95, MHRA Authorisation No: 1443/0001/001-0001, NIHR UKCRN reference 6895, RfPB grant PB-PG-0407-13170_IR5

The Latent Phase of Labor: Diagnosis and Management

The latent phase of labor is complex and not completely understood by modern science. Studies often ignore evaluation of this phase of labor because determination of onset is subjective. In this article, the definition and time parameters of latent phase labor are discussed, and generalized distinctions between prelabor and labor are evaluated. Outpatient relief measures for latent phase as well as inpatient medical interventions for prolonged latent phase of labor are reviewed. Recommendations for policy development are included along with a discussion about the need to consider the significance of time limits. For optimal outcomes, clinicians are encouraged to individualize a management plan that is made in collaboration with the laboring woman.

Epidural analgesia for labor: Current techniques

Epidural analgesia is an extremely effective and popular treatment for labor pain. In this review, we trace the history of the use of epidural analgesia and its refinements. We then outline the goals of treatment and methods used to attain those goals. The use of low concentrations of local anesthetics, combined with lipid-soluble opioids, does not impede the progress of labor or depress the newborn. The incidence of side effects is low. Maintenance of analgesia that allows patient control enhances patient satisfaction.

Parenteral opioids for maternal pain relief in labour

BACKGROUND

Parenteral opioids are used for pain relief in labour in many countries throughout the world.

OBJECTIVES

To assess the acceptability, effectiveness and safety of different types, doses and modes of administration of parenteral opioids given to women in labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2010) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials examining the use of intramuscular or intravenous opioids (including patient controlled analgesia) for women in labour. We looked at studies comparing an opioid with placebo or another opioid.

DATA COLLECTION AND ANALYSIS

At least two review authors independently assessed study eligibility, collected data and assessed risk of bias.

MAIN RESULTS

We included 54 studies involving more than 7000 women that compared an opioid with placebo or another opioid administered intramuscularly or intravenously. The 54 studies reported on 27 different comparisons, and for many outcomes only one study contributed data. Overall the evidence was of poor quality regarding the analgesic effect of opioids, satisfaction with analgesia, adverse effects and harm to women and babies. There were few statistically significant results. Many of the studies had small sample sizes, and low statistical power. Overall, findings indicated that parenteral opioids provided some pain relief and moderate satisfaction with analgesia in labour, although up to two-thirds of women who received opioids reported moderate or severe pain and/or poor or moderate pain relief one or two hours after administration. Opioid drugs were associated with maternal nausea, vomiting and drowsiness, although different opioid drugs were associated with different adverse effects. There was no clear evidence of adverse effects of opioids on the newborn. We did not have sufficient evidence to assess which opioid drug provided the best pain relief with the least adverse effects.

AUTHORS' CONCLUSIONS

Parenteral opioids provide some relief from pain in labour but are associated with adverse effects. Maternal satisfaction with opioid analgesia was largely unreported but appeared moderate at best. We did not examine the effectiveness and safety of parenteral opioids compared with other methods of pain relief in labour and this review needs to be examined alongside related Cochrane reviews. More research is needed to determine which analgesic intervention is most effective, and provides greatest satisfaction to women with acceptable adverse events for mothers and their newborns.

Advances in labor analgesia

The pain of childbirth is arguably the most severe pain most women will endure in their lifetimes. The pain of the early first stage of labor arises from dilation of the lower uterine segment and cervix. Pain from the late first stage and second stage of labor arises from descent of the fetus in the birth canal, resulting in distension and tearing of tissues in the vagina and perineum. An array of regional nerve blocks, systemic analgesic, and nonpharmacologic techniques are currently used for labor analgesia. Nonpharmacologic methods are commonly used, but the effectiveness of these techniques generally lacks rigorous scientific study. Continuous labor support has been shown to decrease the use of pharmacologic analgesia and shorten labor. Intradermal water injections decrease back labor pain. Neuraxial labor analgesia (most commonly epidural or combined spinal-epidural) is the most effective method of pain relief during childbirth, and the only method that provides complete analgesia without maternal or fetal sedation. Current techniques commonly combine a low dose of local anesthetic (bupivacaine or ropivacaine) with a lipid soluble opioid (fentanyl or sufentanil). Neuraxial analgesia does not increase the rate of cesarean delivery compared to systemic opioid analgesia; however, dense neuraxial analgesia may increase the risk of instrumental vaginal delivery.

Educational intervention for obstetrical nurses: introducing intravenous fentanyl to the labour floor

OBJECTIVE

To determine the efficacy of an educational intervention in changing nurses' satisfaction and comfort with and their knowledge and use of a newly introduced analgesic agent, fentanyl, to manage pain during labour.

METHODS

A written survey was completed by 19 labour and delivery nurses before and after the educational intervention in a small Northern Canadian city.

RESULTS

Prior to the educational intervention, respondents rated their knowledge of and comfort with use of morphine and meperidine as significantly greater than their knowledge of and comfort with use of fentanyl (P<0.001 for all comparisons). Following the educational intervention, their knowledge and comfort with use of fentanyl increased to the same level as their knowledge and comfort with use of morphine and meperidine. Knowledge of and comfort with use of morphine and meperidine did not change after the educational intervention, but with use of fentanyl there was a significant increase in both knowledge (P<0.001) and comfort (P<0.001). Use of fentanyl subsequently increased significantly (P=0.016) and the nurses identified fewer barriers to its use. Satisfaction with (and self-reported use of) fentanyl also increased (P=0.001).

CONCLUSION

Participation in education regarding fentanyl increased nurses' knowledge of and comfort and satisfaction with this agent. It also contributed to an increase in the use of this agent, which has been documented to be safer than other narcotics for both mother and baby.

The use of remifentanil in obstetrics

Remifentanil has been proposed as the most suitable systemic opioid for use in obstetrics. Although the onset and offset are rapid, it cannot achieve maximum effect within the time period of a single uterine contraction. Nevertheless, it provides worthwhile analgesia mainly for the first stage of labor with consistently high maternal satisfaction. Maternal oxygen desaturation limits the dose and suitable monitoring during use is advised. As an adjunct to general anesthesia, it is successful in blunting responses to airway manipulation and providing hemodynamic stability in high-risk women. Neonatal effects when used in labor are minimal, but when combined with general anesthesia neonatal depression is unpredictable and more likely with an infusion dose greater than 0.1 microg/kg/min.

Prescribing intramuscular opioids for labour analgesia in consultant-led maternity units: a survey of UK practice

BACKGROUND

Intramuscular opioids are widely used for analgesia in labour. We conducted a postal survey to establish current prescribing and monitoring guidelines for intramuscular opioids in consultant-led obstetric units in the UK.

METHODS

A postal questionnaire was sent between December 2005 and January 2006 to the lead obstetric anaesthetist of all 234 consultant-led obstetric units in the UK. We enquired about dose regimens of intramuscular opioids in labour and monitoring of mother, fetus and neonate.

RESULTS

The response rate was 71%; 84.4% of responding units used pethidine and 34.1% diamorphine. Meptazinol and morphine were available in 13.8% and 13.2% of units respectively. Some units used more than one opioid. The choice of opioid was dictated mainly by tradition (65.3%) and familiarity (40.7%). Prophylactic antiemetics were co-administered in 73.7% of units, the most commonly used being prochlorperazine (30.5%). Vital signs were monitored in 91.6% of units: in total 10.2% measured haemoglobin oxygen saturations and 4.8% respiratory rate. Pain scores were recorded in 13.7% of units.

CONCLUSIONS

When compared with previous studies the use of intramuscular diamorphine is increasing in UK consultant-led obstetric units, although pethidine remains the widely used opioid. At present this change cannot be justified by a suitably powered, randomised study comparing intramuscular pethidine with diamorphine.

WITHDRAWN: Types of intra-muscular opioids for maternal pain relief in labour

BACKGROUND

Pethidine is the most widely used intra-muscular opioid for the relief of labour pain. However concerns have been raised about its effectiveness and the possibility of depressing respiration in newborns.

OBJECTIVES

The objective of this review was to assess the effects of different opioids (and different doses of the same opioid) administered intra-muscularly in labour.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register, the Cochrane Controlled Trials Register (Cochrane Library, issue 4, 1997) and reference lists of articles.

SELECTION CRITERIA

Randomised trials comparing the effects of different currently used opioids (and different doses of the same opioid) administered intramuscularly in labour for women who request systemic analgesia.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed trial quality and extracted data. Analysis was based on the groups as randomly allocated.

MAIN RESULTS

Sixteen trials were included. There were problems with methodological quality of some of the trials, and lack of consistency in the way various outcomes were reported. There was no evidence of a difference between pethidine and tramadol in terms of pain relief, interval to delivery, or instrumental or operative delivery. There appeared to be more adverse effects such as nausea and vomiting and drowsiness with pethidine. Maternal pain relief seemed almost identical between the meptazinol and pethidine groups, whether assessed as maternal satisfaction with pain relief, visual analogue scales, or use of other pain relief, but meptazinol gave rise to slightly more side effects. Maternal satisfaction with pain relief appeared similar for pentazocine and pethidine, with more frequent nausea and vomiting with pethidine.

AUTHORS' CONCLUSIONS

There is not enough evidence to evaluate the comparative efficacy and safety of the various opioids used for analgesia in labour.

Intravenous patient-controlled analgesia for labour: a survey of UK practice

BACKGROUND

Although regional techniques offer superior analgesia during labour, many women receive other methods of pain relief. Furthermore, there is a specific need for analgesia in a small population of labouring women for whom regional techniques are contraindicated, unavailable or impossible to perform. We surveyed current UK practice of labour analgesia for such patients, with particular reference to the use of intravenous patient-controlled analgesia.

METHODS

Following approval from the Obstetric Anaesthetists' Association, a questionnaire was sent to the lead anaesthetic consultants of 243 obstetric units in the United Kingdom. The questionnaire evaluated the availability of methods of pain relief other than regional blocks. Information was sought on patient-controlled intravenous analgesia regimens and patient monitoring.

RESULTS

A total of 159 questionnaires were returned giving a response rate of 65.4%. The majority of units that responded (95.5%) used either intramuscular pethidine or diamorphine. Nearly half (49%) offered patient-controlled intravenous analgesia for labour pain. One third of units (36%) had an analgesic protocol for women in whom regional anaesthetic techniques were contraindicated. With patient-controlled intravenous analgesia, remifentanil (34.6%) was the most commonly used opioid for live births while morphine (35.5%) was used more commonly for deliveries involving intrauterine deaths.

CONCLUSION

The survey demonstrated that, when regional techniques were contraindicated, patient-controlled intravenous opioid analgesia was employed in almost half of the units responding to the questionnaire.