Prophylactic intravenous preloading for regional analgesia in labour

Intravenous infusion route in maternal resuscitation: a scoping review

BACKGROUND

The concept that upper extremities can be used as an infusion route during cardiopulmonary resuscitation in pregnant women is a reasonable recommendation considering the characteristic circulation of pregnant women; however, this method is not based on scientific evidence.

OBJECTIVE OF THE REVIEW

We conducted a scoping review to determine whether the infusion route should be established above the diaphragm during cardiopulmonary resuscitation in a pregnant woman.

DISCUSSION

We included randomized controlled trials (RCTs) and non-RCTs on the infusion of fluids in pregnant women after 20 weeks of gestation requiring establishment of an infusion route due to cardiac arrest, massive bleeding, intra-abdominal bleeding, cesarean section, severe infection, or thrombosis. In total, 3150 articles from electronic database were extracted, respectively. After title and abstract review, 265 articles were extracted, and 116 articles were extracted by full-text screening, which were included in the final analysis. The 116 articles included 78 studies on infusion for pregnant women. The location of the intravenous infusion route could be confirmed in only 17 studies, all of which used the upper extremity to secure the venous route.

CONCLUSION

Pregnant women undergo significant physiological changes that differ from those of normal adults, because of pressure and drainage of the inferior vena cava and pelvic veins by the enlarged uterus. Therefore, despite a lack of evidence, it seems logical to secure the infusion route above the diaphragm when resuscitating a pregnant woman.

Birth outcomes associated with interventions in labour amongst low risk women: A population-based study

INTRODUCTION

Despite concern over high rates of operative birth in many countries, particularly amongst low risk healthy women, the obstetric antecedents of operative birth are poorly described. We aimed to determine the association between interventions introduced during labour with interventions in the birth process amongst women of low medical risk.

METHODS

We undertook a population-based descriptive study of all low risk women amongst the 753,895 women who gave birth in Australia during 2000-2002. Adjusted odds ratios (AOR) were calculated using multinomial logistic regression to describe the association between mode of birth and each of four labour intervention subgroups separately for primiparous and multiparous women.

RESULTS

We observed increased rates of operative birth in association with each of the interventions offered during the labour process. For first time mothers the association was particularly strong.

CONCLUSIONS

This study underlines the need for better clinical evidence of the effects of epidurals and pharmacological agents introduced in labour. At a population level it demonstrates the magnitude of the fall in rates of unassisted vaginal birth in association with a cascade of interventions in labour and interventions at birth particularly amongst women with no identified risk markers and having their first baby. This information may be useful for women wanting to explore other methods of influencing the course of labour and the management of pain in labour, especially in their endeavour to achieve a normal vaginal birth.

Prophylactic intravenous preloading for regional analgesia in labour

BACKGROUND

Reduced uterine blood flow from maternal hypotension may contribute to fetal heart rate changes which are common following regional analgesia (epidural or spinal or combined spinal-epidural (CSE)) during labour. Intravenous fluid preloading may help to reduce maternal hypotension but using lower doses of local anaesthetic, and opioid only blocks, may reduce the need for preloading.

OBJECTIVES

To assess the effects of prophylactic intravenous fluid preloading before regional analgesia during labour on maternal and fetal well-being.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register (19 February 2004).

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing prophylactic intravenous preloading before regional analgesia during labour with a control group (dummy or no preloading).

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied eligibility criteria, assessed trial quality and extracted data.

MAIN RESULTS

Six studies are included (473 participants). In one epidural trial using high-dose local anaesthetic, preloading with intravenous fluids was shown to counteract the hypotension which frequently follows traditional epidural analgesia (relative risk (RR) 0.07, 95% confidence interval (CI) 0.01 to 0.53; 102 women). This trial was also associated with a reduction in fetal heart rate abnormalities (RR 0.36, 95% CI 0.16 to 0.83; 102 women); no differences were detected in other perinatal and maternal outcomes for this trial and another high-dose epidural trial. In the two epidural low-dose anaesthetic trials, no significant difference in maternal hypotension was found (RR 0.73, 95% CI 0.36 to 1.48; 260 women), although they were underpowered to detect less than a very large effect. No significant differences were seen between groups in these trials for fetal heart rate abnormalities (RR 0.64, 95% CI 0.39 to 1.05; 233 women). In the two CSE trials, no differences were reported between preloading and no preloading groups. In the spinal/opioid trial, the RR for hypotension was 0.89, 95% CI 0.43 to 1.83 (40 women) and 0.70, 95% CI 0.36 to 1.37 for fetal heart rate abnormalities (32 women). In the opioid only study (30 women), there were no instances of hypotension or fetal heart rate abnormalities in either group.

REVIEWERS' CONCLUSIONS

Preloading prior to traditional high-dose local anaesthetic blocks may have some beneficial fetal and maternal effects in healthy women. Low-dose epidural and CSE analgesia techniques may reduce the need for preloading. The studies reviewed were too small to show whether preloading is beneficial for women having regional analgesia during labour using the lower-dose local anaesthetics or opioids. Further investigation of low-dose epidural or CSE (including opioid only) blocks, and the risks and benefits of intravenous preloading for women with pregnancy complications, is required.

Complications of obstetric regional analgesia: how much information is enough?

Two hundred parturients who had received epidural analgesia during labour (100 in Melbourne, Australia and 100 in London, UK) were asked on the first postnatal day about their sources of antenatal information on pain relief in labour, their awareness of potential complications of epidural analgesia and the level of risk at which they would wish to be informed before consenting to a procedure. Sources of antenatal information were similar in the two countries although more women in Australia received information from an anaesthetist or obstetrician than in the UK, whilst more women in the UK received information from the media than in Australia. Knowledge of risks was also similar although the Australian subjects were more aware of infective complications while those in the UK were more aware of intravascular injection of local anaesthetic; these differences may reflect recent high-profile cases in the two countries. The preferred level of risk at which women wanted to be informed about a complication varied from 1:1 to 1:1,000,000,000 in all three centres. The majority of women considered that the benefits of epidural analgesia outweighed each of the potential complications. Women differ in their requirements for antenatal information about regional analgesia and its complications, with some wanting to know every complication, however rare. Anaesthetists should be flexible in their disclosure of information when obtaining consent for regional analgesia and consider the particular wishes of each patient rather than follow rigid centralised guidelines.