Submucous paracervical blockade compared with intramuscular meperidine as analgesia during labor: a double-blind study. Spacing the injection interval with paracervical block: a randomized study. Comparison of lidocaine and 2-chloroprocaine in paracervical block: clinical effects and drug concentrations in mother and child. Neonatal monitoring after maternal fentanyl analgesia in labor. Effective obstetric paracervical block with reduced dose of bupivacaine. A prospective randomized double-blind study comparing 25 mg (0.25%) and 12.5 mg (0.125%) of bupivacaine. Which local anesthetic is best suited for paracervical blocks? Obstetrical paracervical block with chloroprocaine or bupivacaine. A comparison. A comparative study of the safety of 0.25% levobupivacaine and 0.25% racemic bupivacaine for paracervical block in the first stage of labor. Marcaine for paracervical anesthesia during labor. Pudendal block in vaginal deliveries. Mepivacaine with and without epinephrine.
A double-blind study was carried out to compare the effect of submucous paracervical blockade using 12 mL 0.25% bupivacaine (55 women) to the effect of intramuscular injection of 75 mg meperidine (62 women) during the first stage of labor. All 117 were normal primiparous pregnancies. Seventy-eight percent of the women in the paracervical blockade group achieved full or acceptable pain relief against 31% in the meperidine group (P less than .01). Transient fetal bradycardia occurred in two cases in the paracervical blockade group and one in the meperidine group; all infants were born in good condition. Fetal distress, defined as an umbilical artery pH of 7.15 or less and/or a one-minute Apgar score of 7 or less was more frequent in the meperidine group (16 infants) than in the paracervical blockade group (six infants) (P less than .05). Submucous paracervical blockade is superior to intramuscular meperidine as pain relief during labor. Furthermore, meperidine results in more infants with asphyxia as compared with paracervical blockade. To test the hypothesis that spacing the injection interval by 10 minutes would reduce the incidence of post-paracervical block bradycardia, 42 healthy subjects at low risk with normal fetal heart rate (FHR) patterns were included in a randomized trial. Twenty patients were given a conventional paracervical block (ie, almost simultaneous injection of the 2 sides), whereas 22 patients were given the second injection after a 10-minute interval. All patients were laterally positioned for 30 minutes before and 60 minutes after administration of the paracervical block. There were no cases of post-paracervical block bradycardia in either group, but a decrease in the baseline FHR of 5 beats per minute or more occurred in one half of each group. Both groups experienced significant decreases in the mean FHR. The authors conclude that patient selection and perhaps lateral positioning are more important than is spacing the injection interval. Furthermore, in properly selected subjects paracervical block offers simple, effective, and safe analgesia. 2-Chloroprocaine (CP) has recently been recommended as a less toxic alternative to amide-type local anesthetics due to its rapid metabolism. A double-blind, randomized study comparing CP to lidocaine when used for paracervical block was carried out. Twenty-nine patients received CP, while 31 received lidocaine. None of the 60 mothers developed adverse side effects. Adequate pain relief was achieved in 28 cases in each group, with a mean duration of 40 min regardless of the anesthetic. No change in uterine activity was observed. In the CP group one fetus had mild bradycardia, while two in the lidocaine group had severe, and three mild bradycardia within 5-7 min after the block. Low concentrations of CP were detected in the venous blood of 2 of 29 mothers and in the umbilical venous blood of their babies. Measurable amounts of its metabolite, 2-chloro-4-aminobenzoic acid (CABA), were found in all 13 samples of maternal blood 5 min after PCB and in 6 of 27 maternal samples at birth. Traces of CABA were found in umbilical venous blood in three neonates; in a fourth, a level of 1,000 ng/ml was found. In contrast, unmetabolized lidocaine was found in all maternal samples and in all but one of the cord samples at birth. Concentration of lidocaine in cord blood at delivery ranged from less than 100 to 4,000 ng/ml and were similar for both arterial and venous samples. No correlation could be demonstrated between levels of local anesthetics in the cord samples and the frequency or severity of fetal bradycardia regardless of the anesthetic. To characterize different methods of monitoring neonatal effects associated with maternal opioid analgesia. Special focus was on the static-charge-sensitive bed (SCSB), which could potentially serve as a non-invasive neonatal monitor.
                12 healthy, term newborns from normal pregnancies were included in this prospective, randomized, controlled study. Maternal labor analgesia was either intravenous fentanyl (n = 5) or paracervical bupivacaine blockade (n = 7). Neonatal recording from delivery to the age of 12 hours included continuous SCSB monitoring with ECG and oximeter for sleep states, respiration, oxygenation, heart rate, and body movements. In addition, umbilical blood pH, Apgar, Amiel-Tison's Neurologic and Adaptive Capacity Scoring (NACS), skin cyanosis scoring, blood pressure, rectal and skin temperatures, and skin blood flow measurements were performed.
                The study was interrupted, because one baby in the fentanyl group had a significant decrease in oxyhemoglobin saturation (SpO2) to 59%. This was considcred to be residual effect of fentanyl and was treated with naloxone. SpO2 was generally lower in the fentanyl group. Epochs with SpO2 < 90% were more frequent in the fentanyl group, especially during active sleep (mean +/- SD 11.9 +/- 10.7% vs. 2.0 +/- 1.7% of epochs, p = 0.034). Mean heart rate values were lower in the fentanyl group (121.1 +/- 6.4 vs. 132.6 +/- 6.8 beats per minute, p = 0.02), and this difference was seen during wake and all sleep states. Maximum heart rate values were lower in the fentanyl group, too. The opiate group had less quiet sleep than controls (9.6 +/- 2.8% vs. 18.3 +/- 8.3%, p = 0.05). NACS after birth was lower in the fentanyl group (median [range] 15 [13-26] vs. 22 [20-25], p = 0.004).
                Several differences were seen between the fentanyl and the control group babies. The SCSB method proved sensitive enough to find neonatal effects of maternal analgesia. Together with ECG and SpO2 monitoring, SCSB gives plentiful information on neonatal well-being in a non-invasive way. Results of this study emphasize the importance of neonatal monitoring after maternal opiate use in labor. To study whether paracervical block (PCB) with 12.5 mg (0.125%) of bupivacaine is as effective as with 25 mg (0.25%) and if there are differences in fetal heart rate (FHR) patterns between the doses.
                A prospective, randomized double-blind study. Fifty-two patients received PCB with 25 mg and 45 patients with 12.5 mg of bupivacaine. Pain intensity was assessed by the patients on a horizontal visual analog scale (VAS). Fetal heart rates of the fetuses were analyzed visually concerning basal rate, variability, accelerations, bradycardia, silent pattern and decelerations.
                The pain relief was statistically significant in both groups up to 120 min after PCB. The VAS-values were similar in both groups both before and after PCB. Fetal heart rate changes appeared in both groups more frequently after than prior to PCB. In patients receiving 25 mg of bupivacaine there appeared to be more FHR changes than in those receiving 12.5 mg.
                Paracervical block with 12.5 mg of bupivacaine is an effective method to relieve pain during labor. Fetal heart rate changes seemed to appear less frequently with this reduced dose. It seems that by lowering the dose of bupivacaine it is possible to reduce fetal side-effects without losing analgesic effect. In a prospective, randomized study the duration and effectiveness of four different regimens of PCB were studied: Bupivacaine both with and without adrenaline, and chloroprocaine with and without adrenaline. The pain relief was immediate and almost complete in most patients in all four treatment groups. The duration of the effect of bupivacaine was the same whether adrenaline was added or not. The labors were significantly prolonged with adrenaline, however. The duration of the effect of chloroprocaine was substantially shorter than bupivacaine, but with this short-lasting anesthetic the duration was prolonged by the addition of adrenaline. It is concluded that bupivacaine without the addition of adrenaline is the drug of choice for PCB. Obstetrical paracervical block was randomly administered to 47 patients, using either 2% chloroprocaine or 0.25% bupivacaine. Analgesia and onset of analgesia were similar for both drugs, but the duration of chloroprocaine was only about half that of bupivacaine (35 min versus 66 min). Fetal bradycardia was encountered in one case after chloroprocaine and in two cases after bupivacaine. It is concluded that chloroprocaine plain is not very suitable for obstetrical paracervical block due to its short duration of action. The objective of the study was to evaluate and compare the safety of levobupivacaine and racemic bupivacaine for paracervical block (PCB) in the first stage of labor after uncomplicated pregnancy.
                Forty women in an open pilot study and 397 women in a double-blind randomized study received PCB for pain relief in the first stage of labor, either with 25 mg of levobupivacaine or with 25 mg of racemic bupivacaine. The incidence of cardiotocographic pathology was compared between the groups using Fisher's exact test. The 95% confidence intervals for the between-group difference were calculated by Newcombe's method.
                In the randomized double-blind study, the incidence of any pathological result in cardiotocography (CTG) was 10.4% in the levobupivacaine group and 12.8% in the racemic bupivacaine group. The incidence of fetal bradycardia in the groups was 2.6 and 3.8%, respectively. All the cardiotocographic changes were transient, and no operative intervention was indicated because of CTG. No difference in the analgesic effect between the drugs was found. Most of the parturients in the levobupivacaine group (97%) and in the racemic bupivacaine group (96%) had spontaneous vaginal delivery. Neonatal outcome was good in both groups.
                No difference in cardiotocographic pathology was found between PCB with levobupivacaine compared with PCB with racemic bupivacaine. The incidence of bradycardia was low. PCB was found to be a safe pain-relief method for low-risk parturients. nan Pudendal block with 20 ml 1% mepivacaine with and without epinephrine was performed in 151 patients during the second stage of labor. No differences in efficacy of the block or in Apgar scores between the two groups were found. The maternal mepivacaine concentration was higher in the plain group than in the epinephrine group (p less than 0.01), but toxic levels were never reached. In the infants, no difference in mepivacaine concentration was found between the groups (p greater than 0.05, type II error 9%) and toxic levels were not reached. The time elapsed from the pudendal block until delivery was prolonged when epinephrine was added (p less than 0.02). We found no effect on blood pressure in either of the groups, with or without oxytocin and/or methergin. Twenty ml 1% mepivacaine (plain) is a safe choice for pudendal block without the possible disadvantages of adding epinephrine.
Local anaesthetic nerve blocks are more effective than placebo, opioid and non-opioid analgesia for pain management in labour based on RCTs of unclear quality and limited numbers. Side effects are more common after local anaesthetic nerve blocks in comparison with placebo. Different local anaesthetic agents used for pain relief provide similar satisfaction with pain relief. Further high-quality studies are needed to confirm the findings, to assess other outcomes and to compare local anaesthetic nerve blocks with various modalities for pain relief in labour.