Dose-response study of spinal hyperbaric ropivacaine for cesarean section

Comparison of Dural Puncture Epidural, Epidural and Combined Spinal-Epidural Anesthesia for Cesarean Delivery: A Randomized Controlled Trial

Purpose

Catheter-based techniques such as combined spinal-epidural (CSE) anesthesia which are sometimes indicated for obstetric anesthesia have a complex mechanism of action. The application of the dural puncture epidural (DPE) anesthesia for cesarean section (CS) has not been well investigated. The present study compared the relatively novel DPE technique with epidural (EA) and CSE anesthesia.

Patients and Methods

We randomly assigned 150 parturients who underwent elective CS to receive DPE, EA or CSE anesthesia. The primary outcome was the onset of sensory anesthesia to the T5 dermatome assessed using the Cox proportional hazards model. Secondary outcomes included median time to sensory block, quality of block, patient and surgeon satisfaction, APGAR scores and other side effects.

Results

For DPE anesthesia versus EA anesthesia, the onset of anesthesia was faster (hazard ratio 2.47 [95% CI 1.56 to 3.90], adjusted P < 0.001) and the median time to surgical level was shorter (16 [IQR 14-18] min versus 19 [15.5-21] min, adjusted P < 0.001); the incidence of intraoperative pain was lower (7/48 versus 17/47, adjusted P = 0.046) and the median patient satisfaction score was higher (9 [IQR 9-10] versus 8 [8-9.5], adjusted P = 0.004). In the CSE group, the onset of anesthesia was faster than in the other two but the incidence of hypotension was higher (P < 0.001) and the phenylephrine requirement was greater (P < 0.001).

Conclusion

DPE anesthesia had a faster onset and better quality of block than EA anesthesia and provided less influence to maternal hemodynamic parameters than CSE anesthesia for CS. These results suggest that the dural puncture plays a significant role in enhancing the effectiveness of epidural top-ups during CSE anesthesia and indicates enlightenment that contributes to the satisfaction of anesthetic effect in DPE technique labor analgesia transferred to CS.

LC-MS/MS quantification of ropivacaine and local analgesic and adverse effects of Long-acting Ropivacaine Injection based on pharmacokinetic-pharmacodynamic modelling in Bama minipigs

The local analgesic efficacy and adverse effects of a new Long-acting Ropivacaine formulation were examined based on pharmacokinetic-pharmacodynamic (PK-PD) modelling in Bama minipigs. 24 Bama minipigs, 12 males and 12 females, were randomly and equally divided into the following treatment groups: normal saline injection, drug vehicle injection, Long-acting Ropivacaine Injection and Ropivacaine Hydrochloride Injection. After routine disinfection, a skin incision about 3 cm long and 3 cm deep was produced in the leg of each pig, and mechanical withdrawal threshold (MWT) measured at various times pre- and post-injection as an index of analgesia against incision pain. Plasma ropivacaine concentrations were also measured at the same times using a novel liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method. Minipigs were sacrificed 24 h post-injection and hearts collected for drug concentration measurements by LC-MS/MS. The LC-MS/MS method demonstrated high sensitivity, linearity and precision. The Long-acting Ropivacaine formulation produced a longer analgesic effect (∼12 h) at a lower plasma concentration than Ropivacaine Hydrochloride (∼4h), suggesting a better side-effects profile. A PK-PD model revealed a direct relationship between plasma ropivacaine concentration and MWT, with peak analgesia at about 1000 ng/mL and behaved good prediction ability. Long-acting Ropivacaine Injection is a superior local anaesthetic-analgesic treatment due to longer-lasting efficacy at lower concentrations compared to Ropivacaine Hydrochloride, which will reduce the risk of side effects such as cardiotoxicity.

A randomised dose-response study of prophylactic Methoxamine infusion for preventing spinal-induced hypotension during Cesarean delivery

BACKGROUND

α-receptor agonists have been reported to be safe and effective for treating or preventing spinal-induced hypotension during cesarean delivery. As a pure α₁ adrenergic agonist, methoxamine has potential advantages of reducing myocardial oxygen consumption and protecting the heart in obstetric patients compared to phenylephrine. The aim of this study was to determine the optimal prophylactic methoxamine infusion dose that would be effective for preventing spinal-induced hypotension in 50% (ED₅₀) and 95% (ED₉₅) of parturients.

METHODS

Eighty parturients with a singleton pregnancy scheduled for elective cesarean delivery were randomly allocated to receive prophylactic methoxamine infusion at one of four different fixed-rates: 1 μg/kg/min (group M1), 2 μg/kg/min (group M2), 3 μg/kg/min (group M3), or 4 μg/kg/min (group M4). An adequate response was defined as absence of hypotension (maternal SBP < 80% of baseline or SBP < 90 mmHg). The values for ED₅₀ and ED₉₅ of prophylactic methoxamine infusion were determined by probit regression model. The outcomes of maternal hemodynamics and fetal status were compared among the groups.

RESULTS

The calculated ED₅₀ and ED₉₅ (95% confidence interval) of prophylactic methoxamine infusion dose were 2.178 (95% CI 1.564 to 2.680) μg/kg/min and 4.821 (95% CI 3.951 to 7.017) μg/kg/min, respectively. The incidence of hypotension decreased with increasing methoxamine infusion dose (15/20, 11/20, 7/20 and 2/20 in group M1, M2, M3 and M4 respectively, P <  0.001). 1-min Apgar scores and umbilical arterial PaO2 were lower but umbilical arterial PaCO2 was higher in Group M1. No difference was found in the other incidence of adverse effects and neonatal outcomes among groups.

CONCLUSIONS

Under the conditions of this study, when prophylactic methoxamine infusion was given at a fixed-rate based on body weight for preventing spinal-induced hypotension in obstetric patients, the values for ED₅₀ and ED₉₅ were 2.178 μg/kg/min and 4.821 μg/kg/min respectively.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR), registry number of clinical trial: ChiCTR-1,800,018,988 , date of registration: October 20, 2018.

Norepinephrine intravenous prophylactic bolus versus rescue bolus to prevent and treat maternal hypotension after combined spinal and epidural anesthesia during cesarean delivery: a sequential dose-finding study

Background

As a relatively new drug in obstetrical anesthesia, norepinephrine is less likely to induce bradycardia and decrease cardiac output, which makes it a potential alternative to phenylephrine. The purpose of this study was to determine the optimal norepinephrine bolus dose needed to either prevent or reverse hypotension after the use of combined spinal and epidural (CSE) anesthesia in 90% of women during elective cesarean delivery (CD).

Methods

Eighty women undergoing elective CD were randomly allocated into either a prophylactic group or a rescue group in this dose finding study. If the women's systolic blood pressure (SBP) was maintained above 80% of their baseline, the next patient had an 8/9^th chance of receiving the same dose or a 1/9^th chance of receiving a lower dose. If the patient's SBP was not maintained, a higher dose was used for next patient. The primary outcome was the successful use of the norepinephrine bolus dose to maintain SBP above 80% of the baseline until after delivery. Secondary outcomes included nausea, vomiting, breathlessness, dizziness, hypertension, bradycardia due to hypotension and supplemental use of atropine and norepinephrine, upper sensory level of anesthesia, umbilical vein (UV) blood gases, and 1- and 5-minute Apgar scores. The 90% effective dose (ED₉₀) and 95% confidence interval (95% CI) were estimated using isotonic regression methods.

Results

The estimated ED₉₀ of the norepinephrine prophylactic bolus was 10.85 µg (95% CI, 9.20-11.67 µg) and that of the norepinephrine rescue bolus was 12.3 µg (95% CI, 10.0-12.8 µg) using isotonic regression methods.

Conclusions

For norepinephrine, either a prophylactic bolus dose of 11 µg or a rescue bolus dose of 12 µg was recommended for clinical practices.

Comparison of the ED50 and ED95 of Intrathecal Bupivacaine in Parturients Undergoing Cesarean Delivery With or Without Prophylactic Phenylephrine Infusion: A Prospective, Double-Blind Study

BACKGROUND AND OBJECTIVES

While prophylactic phenylephrine infusions during cesarean delivery are often used to counteract the sympathectomy associated with spinal anesthesia, their use has been associated with decreased rostral spread of local anesthetic. The purpose of this study was to determine the median effective dose (ED50) and 95% effective dose (ED95) of intrathecal hyperbaric bupivacaine for cesarean delivery in the presence and absence of prophylactic phenylephrine infusion.

METHODS

One hundred healthy parturients undergoing elective cesarean delivery under combined spinal-epidural anesthesia were enrolled in this randomized, double-blind, dose-finding study to determine ED50 and ED95. Subjects were randomly assigned to receive prophylactic phenylephrine or control (saline) infusion with injection of 6, 7.5, 9, 10.5, or 12 mg intrathecal hyperbaric bupivacaine. An effective dose was defined as achieving a T5 sensory level within 10 minutes of intrathecal drug administration without the need for epidural supplementation.

RESULTS

The ED50 of intrathecal hyperbaric bupivacaine was 10.0 mg (95% confidence interval [CI], 5.9-11.4 mg) with prophylactic phenylephrine infusion and 7.9 mg (95% CI, 2.3-9.4 mg) in the control group. The ED95 of intrathecal hyperbaric bupivacaine was 14.1 mg (95% CI, 12.3-37.6 mg) with prophylactic phenylephrine infusion and 11.7 mg (95% CI, 9.9-22.8 mg) in the control group.

CONCLUSIONS

The administration of prophylactic phenylephrine infusion results in higher intrathecal hyperbaric bupivacaine dosing requirements in parturients undergoing cesarean delivery.

CLINICAL TRIAL REGISTRATION

This study was registered at the Chinese Clinical Trial Registry, identifier ChiCTR-TRC-16008938.

ED50 and ED95 of intrathecal hyperbaric ropivacaine for parturients undergoing cesarean section with prophylactic infusion of phenylephrine: A Prospective dose-finding Study

BACKGROUND

Studies have reported that the ED50 of intrathecal ropivacaine was increased when using prophylactic infusion of phenylephrine to prevent spinal-induced hypotension. However, ED95 is more meaningful to clinical practice than ED50. Therefore, we conducted this study to determine the 95% effective dose (ED95) of intrathecal hyperbaric ropivacaine for cesarean section in parturients receiving prophylactic infusion of phenylephrine to prevent spinal-induced hypotension.

METHODS

A hundred of healthy parturients undergoing elective cesarean section under combined spinal-epidural anesthesia (CSEA) were enrolled in this randomized, double-blinded, dose-ranging study. Patients were randomly assigned to receive 7, 9, 11, 13 or 15 mg intrathecal hyperbaric ropivacaine respectively. The prophylactic phenylephrine infusion (50 μg/min) was initiated immediately at the same time of spinal injection. Successful spinal anesthesia was defined as a T5 sensory level achieved within 10 min after intrathecal drug administration and no epidural supplement was required during the surgery. The ED95 was calculated with Probit analysis.

RESULTS

The ED95 of intrathecal ropivacaine with 5 μg sufentanil for successful anesthesia was 15.2 mg (95%CI, 13.5-18.8 mg), when receiving prophylactic infusion of phenylephrine.

CONCLUSION

Under the conditions of the present study, the ED95 of intrathecal hyperbaric ropivacaine for successful spinal anesthesia for cesarean section in healthy parturient receiving prophylactic infusion of phenylephrine was 15.2 mg.

The Dose-response of Intrathecal Ropivacaine Co-administered with Sufentanil for Cesarean Delivery under Combined Spinal-epidural Anesthesia in Patients with Scarred Uterus

Background:

Spinal anesthesia is considered as a reasonable anesthetic option in lower abdominal and lower limb surgery. This study was to determine the dose-response of intrathecal ropivacaine in patients with scarred uterus undergoing cesarean delivery under combined spinal-epidural anesthesia.

Methods:

Seventy-five patients with scarred uterus undergoing elective cesarean delivery under combined spinal-epidural anesthesia were enrolled in this randomized, double-blinded, dose-ranging study. Patients received 6, 8, 10, 12, or 14 mg intrathecal hyperbaric ropivacaine with 5 μg sufentanil. Successful spinal anesthesia was defined as a T₄ sensory level achieved with no need for epidural supplementation. The 50% effective dose (ED₅₀) and 95% effective dose (ED₉₅) were calculated with a logistic regression model.

Results:

ED₅₀ and ED₉₅ of intrathecal hyperbaric ropivacaine for patients with scarred uterus undergoing cesarean delivery under combined spinal-epidural anesthesia (CSEA) were 8.28 mg (95% confidence interval [CI]: 2.28–9.83 mg) and 12.24 mg (95% CI: 10.53–21.88 mg), respectively.

Conclusion:

When a CSEA technique is to use in patients with scarred uterus for an elective cesarean delivery, the ED₅₀ and ED₉₅ of intrathecal hyperbaric ropivacaine along with 5 μg sufentanil were 8.28 mg and 12.24 mg, respectively. In addition, this local anesthetic is unsuitable for emergent cesarean delivery, but it has advantages for ambulatory patients.

ED 50 and ED 95 of intrathecal bupivacaine coadministered with sufentanil for cesarean delivery under combined spinal-epidural in severely preeclamptic patients

Background:

Spinal anesthesia was considered as a reasonable anesthetic option in severe preeclampsia when cesarean delivery is indicated, and there is no indwelling epidural catheter or contraindication to spinal anesthesia. However, the ideal dose of intrathecal bupivacaine has not been quantified for cesarean delivery for severe preeclamptic patients. This study aimed to determine the ED₅₀ and ED₉₅ of intrathecal bupivacaine for severely preeclamptic patients undergoing elective cesarean delivery.

Methods:

Two hundred severely preeclamptic patients are undergoing elective cesarean delivery under combined spinal-epidural anesthesia enrolled in this randomized, double-blinded, dose-ranging study. Patients received 4 mg, 6 mg, 8 mg, or 10 mg intrathecal hyperbaric bupivacaine with 2.5 μg sufentanil. Successful spinal anesthesia was defined as a T6 sensory level achieved within 10 minutes after intrathecal drug administration and/or no epidural supplement was required during the cesarean section. The ED₅₀ and ED₉₅ were calculated with a logistic regression model.

Results:

ED₅₀ and ED₉₅ of intrathecal bupivacaine for successful spinal anesthesia were 5.67 mg (95% confidence interval [CI]: 5.20–6.10 mg) and 8.82 mg (95% CI: 8.14–9.87 mg) respectively. The incidence of hypotension in Group 8 mg and Group 10 mg was higher than that in Group 4 mg and Group 6 mg (P < 0.05). The sensory block was significantly different among groups 10 minutes after intrathecal injection (P < 0.05). The use of lidocaine in Group 4 mg was higher than that in other groups (P < 0.05). The use of phenylephrine in Group 8 mg and Group 10 mg was higher than that in the other two groups (P < 0.05). The lowest systolic blood pressure before the infant delivery of Group 8 mg and Group 10 mg was lower than the other two groups (P < 0.05). The satisfaction of muscle relaxation in Group 4 mg was lower than other groups (P < 0.05). There was no significant difference in patients’ satisfaction and the newborns’ Apgar score and the blood gas analysis of umbilical artery serum (P > 0.05).

Conclusion:

Our study showed that the ED₅₀ and ED₉₅ of intrathecal bupivacaine for severely preeclamptic patients undergoing elective cesarean delivery were 5.67 mg and 8.82 mg, respectively. In addition, decreasing the dose of intrathecal bupivacaine could reduce the incidence of maternal hypotension.

Update on the clinical utility and practical use of ropivacaine in Chinese patients

We reviewed the Chinese and English literature for efficacy and tolerability data as well as pharmacological properties of ropivacaine in Chinese patients. Ropivacaine is a long-acting amide local anesthetic agent that elicits nerve block via reversible inhibition of sodium ion influx in nerve fibers. The available evidence in the literature on anesthesia practice indicates that ropivacaine produces equally surgical sensory block and postoperative and obstetrics analgesia with good maternal and fetal outcome to those of bupivacaine or levobupivacaine. It appears to be associated with comparable onset, quality, and duration of sensory block, but with a lower incidence or grade of motor block, compared to bupivacaine. The satisfaction of both patients and surgeons is high when ropivacaine is used. Thus, ropivacaine appears to be an important option for regional anesthesia and for the management of postoperative and labor pain, with its enhanced sensorimotor differentiation blockage at lower concentrations and enhanced safety at higher concentrations.

Prevention of hypotension and prolongation of postoperative analgesia in emergency cesarean sections: A randomized study with intrathecal clonidine

Background and Context:

Different adjuvants been tried out for neuraxial anesthesia in emergency caesarean section so that the dose of the local anesthetic can be reduced and hypotension thereby prevented.

Aims and Objectives:

The present study was carried out in patients presenting for emergency lower segment caesarean section (LSCS) to establish the dose of intrathecal clonidine that would allow reduction of the dose of local anesthetic (thereby reducing the incidence and magnitude of hypotension) while at the same time providing clinically relevant prolongation of spinal anesthesia without significant side effects.

Materials and Methods:

This randomized clinical study was carried out in our institution among 100 pregnant females who underwent emergency caesarean section. The participants were divided randomly into four groups: A, B, C, and D, each comprising 25 parturients. Subarachnoid block was performed using a 26G Quincke needle, with 12 mg of hyperbaric bupivacaine (LA) in group A, 9 mg of LA + 30 μg of clonidine in group B, LA + 37.5 μg of clonidine in group C, and LA + 45 μg of clonidine in group D. The solution was uniformly made up to 2.2 mL with normal saline in all the groups. Onset of analgesia at T₁₀ level, sensory and motor blockade levels, maternal heart rate and blood pressure, neonatal Apgar scores, postoperative block characteristics, and adverse events were looked for and recorded. Statistical analysis was carried out with SPSS^® version 10.0 for Windows^®, using the ANOVA test with post hoc significance, the Chi-square test, and the Mann-Whitney U test. P<.05 was considered significant and P<.0001 as highly significant.

Results:

One hundred patients were enrolled for this study. The four groups were comparable with regard to demographic data and neonatal Apgar scores. Onset and establishment of sensory and motor analgesia was significantly shorter in groups C and D, while hypotension (and the use of vasopressors) was significantly higher in groups A and D. Perioperative shivering, nausea, and vomiting were significantly higher in groups A and D, while incidence of dry mouth was significantly higher in group D.

Conclusions:

The addition of 45 μg, 37.5 μg, and 30 μg of clonidine to hyperbaric bupivacaine results in more prolonged complete and effective analgesia, allowing reduction of up to 18% of the total dose of hyperbaric bupivacaine. From the results of this study, 37.5 μg of clonidine seems to be the optimal dose.

Intrathecal sufentanil decreases the median effective dose (ED50) of intrathecal hyperbaric ropivacaine for caesarean delivery

BACKGROUND

The addition of opioid to local anaesthetics has become a well-accepted practice of spinal anaesthesia for caesarean delivery. Successful caesarean delivery anaesthesia has been reported with the use of a low dose of intrathecal hyperbaric ropivacaine coadministered with sufentanil. This prospective, double-blinded study determined the median effective dose (ED50) of intrathecal hyperbaric ropivacaine with and without sufentanil for caesarean delivery, to quantify the sparing effect of sufentanil on the ED50 of intrathecal hyperbaric ropivacaine.

METHODS

Sixty-four parturients undergoing elective caesarean delivery with combined spinal-epidural anaesthesia were randomized into two groups: Group R (ropivacaine) and Group RS (ropivacaine plus sufentanil 5 microg). The initial dose of ropivacaine was 13 mg in Group R and 10 mg in Group RS. The effective dose was defined as a T(6) level attained within 10 min and no supplemental epidural anaesthetic required during surgery. Effective or ineffective responses determined, respectively, a 0.3 mg decrease or increase of the dose of ropivacaine for the next patient using an up-down sequential allocation.

RESULTS

The ED50 of intrathecal ropivacaine was 11.2 mg [confidence interval (CI) 95%: 11.0-11.6] in Group R vs. 8.1 mg (CI 95%: 7.8-8.3) in Group RS. Motor block was markedly more intense in Group R than in Group RS, and the incidence of shivering was lower in Group RS than in Group R. There were no differences in the onset time of sensory block or motor block, in the incidence of hypotension, nausea and vomiting.

CONCLUSION

Intrathecal sufentanil 5 microg produced a 28% reduction of ED50 of intrathecal hyperbaric ropivacaine for caesarean delivery.