A comparison of the inhibitory effects of bupivacaine and levobupivacaine on isolated human pregnant myometrium contractility

Analgesia during Parturition in Domestic Animals: Perspectives and Controversies on Its Use

This article analyzes the physiological role of pain during parturition in domestic animals, discusses the controversies surrounding the use of opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local analgesics as treatments during labor, and presents the advantages and disadvantages for mother and offspring. Labor is a potentially stressful and painful event, due to the contractions that promote expulsion of the fetus. During labor, neurotransmitters such as the prostaglandins contribute to the sensitization of oxytocin receptors in the myometrium and the activation of nociceptive fibers, thus supporting the physiological role of pain. Endogenously, the body secretes opioid peptides that modulate harmful stimuli and, at the same time, can inhibit oxytocin's action in the myometrium. Treating pain during the different stages of parturition is an option that can help prevent such consequences as tachycardia, changes in breathing patterns, and respiratory acidosis, all of which can harm the wellbeing of offspring. However, studies have found that some analgesics can promote myometrial contractility, increase expulsion time, affect fetal circulation, and alter mother-offspring recognition due to hypnotic effects. Other data, however, indicate that reducing the number of uterine contractions with analgesics increases their potency, thus improving maternal performance. Managing pain during labor requires understanding the tocolytic properties of analgesics and their advantages in preventing the consequences of pain.

The effects of epidural analgesia using low-concentration local anesthetic during the entire labor on maternal and neonatal outcomes: a prospective group study

PURPOSE

The purpose of this study was to study the impact of epidural analgesia using low-concentration local anesthetic during the entire labor on maternal and neonatal outcomes.

METHODS

The authors enrolled 2310 parturient mothers who underwent vaginal delivery at their hospital since January 1, 2019. The parturients were allocated either into the analgesia or into the non-analgesia groups based on whether they received analgesia during the delivery process. To investigate the effects of epidural analgesia using low-concentration local anesthetic on maternal and neonatal outcomes, the authors assessed between-group differences in the labor duration, newborn Apgar score, and maternal and neonatal outcomes.

RESULTS

Compared to the non-analgesia group, the first and second labor stage durations in the analgesia group were significantly longer. Similarly, the analgesia group had a higher frequency of oxytocin injections, Category II and III fetal heart rate tracing during labor, and intrapartum fever development. Further, the need for episiotomy and assisted vaginal delivery was higher in the analgesia group than that in the non-analgesia group. Regarding neonatal outcomes, the neonatal hospitalization rate and incidence rate of umbilical cord blood pH < 7.2 were higher in the analgesia group than those in the non-analgesia group. However, there were no significant between-group differences in the incidence rates of stained amniotic fluid, mild neonatal asphyxia, and severe perinatal asphyxia.

CONCLUSION

Patient-controlled epidural analgesia using low-concentration local anesthetic during the entire labor did not increase the incidence rate of severe adverse outcomes in neonates born through vaginal delivery; however, it increased the delivery duration, and thus, the chance of possible perinatal interventions.

Uterine contractility changes in a perfused swine uterus model induced by local anesthetics procaine, lidocaine, and ropivacaine

Background

Local anesthetics (LAs) are increasingly used as therapeutics due to their multiple molecular effects. They may be potential agents also in gynecology and reproductive medicine. The objective of this study was to investigate the contractility response of the perfused swine uterus to different concentrations of the LAs procaine, lidocaine, and ropivacaine.

Methods and findings

In an extracorporeal perfusion model with fresh swine uteri, effects of administered boli of these three LAs in concentrations of 0.1 mg/mL, 0.5 mg/mL and 1.0 mg/mL on uterine contractility and peristalsis were assessed using an intrauterine double-chip micro-catheter. A dose-dependent increase in intrauterine pressure (IUP) in the isthmus and corpus uteri was observed after the administration of the ester-LA procaine 0.1, 0.5, and 1.0%, which was not seen with lower concentrations, or buffer solution. An increase-decrease curve was found after increasing concentrations of the amide-LA lidocaine and ropivacaine, with an IUP plateau with 0.1 and 0.5%, and a decrease with 1% (p<0.01). All reactions were seen in both the isthmus and corpus uteri. The difference of the contractility pattern between ester- and amide-LA at 1% concentration was significant.

Conclusion

LAs dose-dependently modulate contractility in non-pregnant swine uteri. The amid-LAs lidocaine and ropivacaine reduce contractility in higher concentrations and may be used as therapeutics in disorders with increased uterine contractility, as dysmenorrhoea, endometriosis, and infertility. The multiple molecular effects of LAs may explain these effects. This in-vitro pilot study in vitro provides initial data for designing further studies to transfer the results onto humans.

Effects of Ropivacaine in Patient-Controlled Epidural Analgesia on Uterine Electromyographic Activities during Labor

Epidural analgesia is effective in relieving pain during labor. However, concerns as to compromised labor progress and outcomes arise. This study aimed to assess the effect of patient-controlled epidural analgesia (PCEA) with ropivacaine on uterine electromyography (EMG) activities and outcomes in labor. A total of 213 pregnant women were divided into three groups: the PCEA with ropivacaine group (n = 78), the PCEA with levobupivacaine group (n = 66), and a control group that did not receive PCEA (n = 69). Uterine EMG activities were recorded during the first stage of labor. Maternal and fetal outcomes also were assessed. The primary outcomes of this study were EMG activities. No significant differences were observed in patient demographics or neonatal weight among the three groups. Compared to the PCEA with levobupivacaine group, the control and PCEA with ropivacaine groups had lower rates of oxytocin administration (P < 0.05) and shorter durations of the first stage of labor (P < 0.05). For the EMG activities, the PCEA with ropivacaine group showed a higher power (P < 0.01) and higher peak frequency (P < 0.05) than the PCEA with levobupivacaine group. With ropivacaine, the EMG activities remained stable 30–120 min. Compared with levobupivacaine, the use of ropivacaine in PCEA has no suppressive effect on uterine EMG activities during the first stage of labor. In addition, ropivacaine leads to labor progress and delivery outcomes similar to those in the control group, as well as similar and favorable analgesic satisfaction with the use of levobupivacaine.

Uterine and Abdominal Muscle Electromyographic Activities in Control and PCEA-Treated Nulliparous Women During the Second Stage of Labor

OBJECTIVE

Patient-controlled epidural analgesia (PCEA), used to relieve pain during delivery, delays labor but the mechanism is unknown. The aim was to investigate the effects of PCEA on uterine and abdominal muscles electromyographic (EMG) activity during the second stage of labor.

METHODS

This study included 45 nulliparous pregnant women without PCEA, 42 women with standard PCEA treatment given during the first stage of labor and stopped near the end of the first stage, and 22 women with standard PCEA treatment with continued use throughout the first and second stages of labor. The EMG signals were recorded from the abdominal surface using PowerLab hardware and LabChart software (ADInstruments, New South Wales, Australia) and filtered to separate uterine and abdominal EMG. Various EMG burst parameters were obtained.

RESULTS

There are no differences ( P > .05) in the age, body mass index, fetal weight, and Apgar scores between the patients from the various groups. PCEA (both stopped and continued) inhibits ( P < .05) duration, number of bursts, and root mean square of uterine EMG. PCEA also produces statistically significant ( P < .001) reductions in abdominal EMG. The decrease in EMG activity is accompanied by a significant ( P < .001) prolongation of the second stage duration (PCEA continued = 95.08 ± 8.60 minutes, PCEA stopped = 79.39 ± 6.25 minutes, no PCEA = 61.00 ± 7.23 minutes).

CONCLUSION

PCEA suppresses uterine and abdominal muscle EMG during the second stage of labor but inhibition depends upon the treatment schedule. PCEA prolongs the duration of labor by inhibition of uterine and abdominal muscle and neural activity.

In vivo comparison of the effects of bupivacaine and levobupivacaine on the pregnant rat myometrium using electrohysterogram

BACKGROUND AND AIMS

The effect of local anesthetics on myometrial contractility during labor analgesia is debatable. We aimed to compare the effects of bupivacaine and levobupivacaine on rat uterine contractility in an in vivo setting.

METHODS

Electrical activities of 40 pregnant rat uteruses were recorded on electrohysterogram after dividing the rats into bupivacaine and levobupivacaine groups. Uterine contraction frequencies were recorded at each 5-min interval. The first 5-min recording was considered the control, which was immediately followed by intramyometrial administration of either bupivacaine or levobupivacaine. The recordings were continued for 30 min. The changes in frequencies at each time interval of the groups were compared with each other and the control recording.

RESULTS

The frequencies from both groups at each interval were lower than the control values, but not different between the groups. The frequencies of the bupivacaine group during the 5-10 min and 10-15 min intervals were lower than the control time interval, but no significant differences were present between the control and the other time intervals. However, no significant differences were found at any time interval for the levobupivacaine group.

CONCLUSION

Levobupivacaine led to less muscle relaxation compared to bupivacaine and may be a better option for labor analgesia and anesthesia considering uterine contractility.