Normal saline i.v. fluid load decreases uterine activity in active labour. An intravenous fluid bolus is not necessary before administration of intrathecal fentanyl for labor analgesia. A randomised controlled trial of fluid pre-loading before low dose epidural analgesia for labour. Fluid loading to reduce abnormalities of fetal heart rate and maternal hypotension during epidural analgesia in labour. Randomized study of intravenous fluid preload before epidural analgesia during labour.
This study was designed to observe the effects of i.v. fluid infusion on uterine activity during normal labour in women receiving an extradural block. Thirty-four women in spontaneous labour at term gestation were allocated randomly and prospectively to one of three i.v. pre-extradural fluid load groups: group A, no fluid load; group B, normal saline 500 ml; and group C, normal saline 1000 ml. Continuous internal measurement of uterine activity was observed before, during and after fluid infusion and extradural block. In groups A and B, uterine activity did not change. In group C, uterine activity decreased after infusion of saline (P < 0.01) and returned to baseline over the next 20 min. Extradural block was not associated with a change in uterine activity. Hypotension was not increased in the group that received no fluid preload. To determine if an intravenous (i.v.) fluid bolus is necessary to prevent any possible hemodynamic sequelae after administration of intrathecal fentanyl in laboring parturients.
                Prospective, randomized study.
                Labor suite of a women's tertiary care hospital.
                30 ASA physical status I and II parturients in active labor requesting labor analgesia.
                Patients were randomly divided into two groups of 15. One group received no i.v. fluid prior to the administration of 25 micrograms of intrathecal fentanyl, and the other group received 500 ml of lactated Ringer's solution before the block.
                Blood pressures [systolic (SBP), diastolic (DBP), mean (MAP)], heart rate (HR), cardiac index (CI; using impedance cardiography), and visual analog scores were measured before the block, after fluids, and then every 5 minutes for 45 minutes after the block. Prenatal baseline blood pressures before the onset of labor were obtained from the obstetrician's office records. Results were analyzed using analysis of variance. All patients reported good pain relief. No patient from either group required treatment for hypotension. In the no fluid group, SBP and MAP decreased 10% and 14%, respectively (p = 0.05), following intrathecal fentanyl administration compared with preblock values obtained during labor but not when compared with prelabor prenatal values. In the fluid group, no significant changes occurred in SBP after intrathecal fentanyl but MAP decreased approximately 12% only in comparison to preblock values. No significant changes were noted in CI in either group. Fluid infusion itself caused an increase in HR and CI of approximately 12% and 9.4%, respectively.
                Intrathecal fentanyl produces only minimal hemodynamic changes with or without prior fluid administration. Preloading with fluid is recommended before regional block in labour. Low dose epidurals may produce less haemodynamic disturbance than traditional stronger solutions of local anaesthetics. Our aim was to compare the incidence of hypotension in normal labouring women who received a low dose epidural (0.1% bupivacaine 15 mL with fentanyl 2 microg microg.mL(-1)) with and without an i.v. crystalloid preload. Women with normal labours were randomised to the intervention group: no i.v. crystalloid preload (n = 85) and the control group: 7 mL mL.kg(-1) i.v. crystalloid solution before epidural injection (n = 83). Mean arterial pressure was recorded every 5 min for 30 min. There was no difference between the groups in mean decrease in mean arterial pressure and similar proportions of women showed falls in mean arterial pressure of 20% or greater (13% vs. 11%, risk ratio 1.2, 95% CI 0.54 to 2.8, P = 0.6). Blinded analysis by independent obstetricians revealed no differences in the fetal heart rate abnormalities (20% vs. 15%, risk ratio 1.3, 95% CI 0.67 to 2.7). A scientifically valid conclusion whether preloading is useful cannot be drawn from this study. This study suggests that about 350 participants in each group would be necessary to exclude a type 2 error in a future study. Fetal heart rate (FHR) was recorded and maternal blood pressure measured in 104 patients in whom lumbar epidural analgesia was induced in labour. Fifty-one patients received an intravenous load of 11 of Hartmann's solution immediately before the epidural injection. This infusion significantly reduced the incidence of abnormalities of FHR from 34% to 12% and of maternal hypotension from 28% to 2%. We did not study mothers with pre-eclampsia and hypertension, but we conclude that there is a strong case for preloading all other mothers in whom lumbar epidural analgesia is induced in labour. We performed a randomized controlled trial of the effect of intravenous fluid preload on maternal hypotension and fetal heart rate (FHR) changes in labour after the first epidural injection. Group 1 (49 women) received 1 litre of crystalloid preload. Group 2 (46 women) received no preload. No statistically significant difference was shown between the two groups for either of the outcomes. Hypotension was found in three women in group 1 and five in group 2 (P = 0.4). Deterioration in FHR pattern was found in four women in group 1 and 11 in group 2 (P = 0.08). This study has not shown a significant increase in the incidence of hypotension when intravenous preload is omitted before epidural analgesia using a low concentration of bupivacaine during labour. Because of the clinical importance of the difference in the rate of FHR deterioration between the two groups, we continue to administer preload for high-risk cases.
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.
[Note: The five citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]