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

Inadequate Spinal Anesthesia in Lumbar Spine Surgery Is Related to Volume of the Thecal Sac

BACKGROUND

Spinal anesthesia (SA) is used in lumbar surgery, but initial adequate analgesia fails in some patients. In these cases, spinal redosing or conversion to general endotracheal anesthesia is required, both of which are detrimental to the patient experience and surgical workflow.

METHODS

We reviewed cases of lumbar surgery performed under SA from 2017-2021. We identified 12 cases of inadequate first dose and then selected 36 random patients as controls. We used a measurement tool to approximate the volume of the dural sac for each patient using T2-weighted sagittal magnetic resonance imaging sequences.

RESULTS

Patients who had an inadequate first dose of anesthesia had a significantly larger dural sac volume, 22.8 ± 7.9 cm3 in the inadequate dose group and 17.4 ± 4.7 cm3 in controls (P = 0.043). The inadequate dose group was significantly younger, 54.2 ± 8.8 years in failed first dose and 66.4 ± 11.9 years in controls (P = 0.001). The groups did not differ by surgical procedure (P = 0.238), level (P = 0.353), American Society of Anesthesia score (P = 0.546), or comorbidities.

CONCLUSIONS

We found that age, larger height, and dural sac volume are risk factors for an inadequate first dose of SA. The availability of spinal magnetic resonance imaging in patients undergoing spine surgery allows the preoperative measurement of their thecal sac size. In the future, these data may be used to personalize spinal anesthesia dosing on the basis of individual anatomic variables and potentially reduce the incidence of failed spinal anesthesia in spine surgery.

Comparison of equipotent doses of intrathecal hyperbaric prilocaine 2% and hyperbaric bupivacaine 0.5% for elective caesarean section: A prospective, randomised, controlled, two-centre clinical trial

BACKGROUND

Elective caesarean section is performed mainly under spinal anaesthesia using hyperbaric bupivacaine combined with opioids. Despite rapid onset, good quality anaesthesia, bupivacaine provides a long duration of motor block and is related to maternal hypotension. Current policies appeal for implementation of enhanced recovery procedures after caesarean section. Hyperbaric prilocaine is an intermediate-acting local anaesthetic known for its efficacy in ambulatory surgery. Evidence on the clinical relevance of intrathecal prilocaine use for caesarean section is currently lacking.

OBJECTIVES

We aimed to investigate whether hyperbaric prilocaine would offer a shorter motor block and recovery than bupivacaine, when comparing equipotent doses. We also assessed the characteristics of sensory block, maternal haemodynamics and side effects for both mother and newborn.

DESIGN

Prospective, randomised, double-blind, controlled, two-centre, clinical trial.

SETTING

One university teaching hospital and one general teaching hospital in Brussels, Belgium.

PATIENTS

American Society of Anesthesiologists' physical status 2 parturients (n = 40) undergoing caesarean section under spinal anaesthesia.

INTERVENTIONS

Patients were randomly assigned to receive spinal anaesthesia using hyperbaric prilocaine 50 mg or hyperbaric bupivacaine 10 mg, both given with sufentanil 2.5 μg and morphine 100 μg. An epidural catheter was introduced as a backup in case of failure.

MAIN OUTCOMES

The primary outcome was the motor block regression (modified Bromage scale 1 to 6). Secondary outcomes included sensory block characteristics, first unassisted ambulation, maternal side effects, newborns' parameters and overall satisfaction.

RESULTS

Median [IQR] motor block was significantly shorter in the hyperbaric prilocaine group (110 [104 to 150] min versus 175 [135 to 189] min, P = 0.001). First unassisted ambulation was achieved earlier after prilocaine (204.5 [177 to 246.5] min versus 314 [209.25 to 400] min, P = 0.007), and the incidence of maternal hypotension was significantly higher with bupivacaine (P = 0.033). No supplementary epidural analgesia was needed.

CONCLUSION

Prilocaine provides shorter motor block, faster recovery and better haemodynamic stability than bupivacaine while offering equivalent surgical anaesthesia.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT02973048, EudraCT: 2016-003010-26.

Hyperbaric prilocaine vs. hyperbaric bupivacaine for spinal anaesthesia in women undergoing elective caesarean section: a comparative randomised double-blind study

Hyperbaric bupivacaine spinal anaesthesia remains the gold standard for elective caesarean section, but the resultant clinical effects can be unpredictable. Hyperbaric prilocaine induces shorter motor block but has not previously been studied in the obstetric spinal anaesthesia setting. We aimed to compare duration of motor block after spinal anaesthesia with prilocaine or bupivacaine during elective caesarean section. In this prospective randomised, double-blind study, women with uncomplicated pregnancy undergoing elective caesarean section were eligible for inclusion. Exclusion criteria included: patients aged < 18 years; height < 155 cm or > 175 cm; a desire to breastfeed; or a contra-indication to spinal anaesthesia. Patients were randomly allocated to two groups: the prilocaine group underwent spinal anaesthesia with 60 mg intrathecal prilocaine; and the bupivacaine group received 12.5 mg intrathecal heavy bupivacaine. Both 2.5 µg sufentanil and 100 µg morphine were added to the local anaesthetic agent in both groups. The primary outcome was duration of motor block, which was assessed every 15 min after arriving in the post-anaesthetic care unit. Maternal haemodynamics, APGAR scores, pain scores, patient satisfaction and side-effects were recorded. Fifty patients were included, with 25 randomly allocated to each group. Median (IQR [range]) motor block duration was significantly shorter in the prilocaine group, 158 (125-188 [95-249]) vs. 220 (189-250 [89-302]) min, p < 0.001. Median length of stay in the post-anaesthetic care unit was significantly shorter in the prilocaine group, 135 (120-180 [120-230]) vs. 180 (150-195 [120-240]) min, p = 0.009. There was no difference between groups for: maternal intra-operative hypotension; APGAR score; umbilical cord blood pH; maternal postoperative pain; and patients' or obstetricians' satisfaction. We conclude that hyperbaric prilocaine induces a shorter and more reliable motor block than hyperbaric bupivacaine for women with uncomplicated pregnancy undergoing elective caesarean section.

Fixed Dose versus Height-Adjusted Conventional Dose of Intrathecal Hyperbaric Bupivacaine for Caesarean Delivery: A Prospective, Double-Blinded Randomised Trial

The optimal intrathecal dose of local anaesthetic for caesarean section (CS) anaesthesia is still being debated. We performed a study to compare the effectiveness and safety of spinal anaesthesia with 12.5 mg of hyperbaric bupivacaine and a dosing regimen of conventional doses adjusted to parturient height. One hundred and forty parturients scheduled for elective CS were enrolled. The fixed-dose group (FD) received a spinal block with 12.5 mg of hyperbaric bupivacaine with fentanyl, whereas the adjusted-dose group (AD) received a height-adjusted dose of bupivacaine (9-13 mg) with fentanyl. Sensory block ≥ T5 dermatome within 10 min and no need for supplementary analgesia were set as the composite primary outcome (success). Rates of successful blocks and complications were compared. Complete data were available for 134 cases. Spinal anaesthesia was successful in 58 out of 67 patients in the FD group and 57 out of 67 in the AD group (p > 0.05). Eight spinals in each group failed to produce a block ≥ T5 in 10 min, and one patient in the FD group and two in the AD group required i.v. analgesics despite sensory block ≥ T5. No differences were noted in terms of hypotension, bradycardia and nausea between the FD and AD groups. Compared to the height-adjusted dose regimen based on conventional doses of hyperbaric bupivacaine, the fixed dose regimen of 12.5 mg was equally effective and did not increase the risk of spinal block-related complications.

The Effect of Prophylactic Phenylephrine and Ephedrine Infusions on Umbilical Artery Blood pH in Women With Preeclampsia Undergoing Cesarean Delivery With Spinal Anesthesia: A Randomized, Double-Blind Trial

BACKGROUND

Spinal anesthesia for cesarean delivery is associated with a high incidence of hypotension. Phenylephrine results in higher umbilical artery pH than ephedrine when used to prevent or treat hypotension in healthy women. We hypothesized that phenylephrine compared to ephedrine would result in higher umbilical artery pH in women with preeclampsia undergoing cesarean delivery with spinal anesthesia.

METHODS

This study was a randomized double-blind clinical trial. Nonlaboring women with preeclampsia scheduled for cesarean delivery with spinal anesthesia at Prentice Women's Hospital of Northwestern Medicine were randomized to receive prophylactic infusions of phenylephrine or ephedrine titrated to maintain systolic blood pressure >80% of baseline. Spinal anesthesia consisted of hyperbaric 0.75% bupivacaine 12 mg, fentanyl 15 µg, and morphine 150 µg. The primary outcome was umbilical arterial blood pH and the secondary outcome was umbilical artery base excess.

RESULTS

One hundred ten women were enrolled in the study and 54 per group were included in the analysis. There were 74 and 72 infants delivered in the ephedrine and phenylephrine groups, respectively. The phenylephrine:ephedrine ratio for umbilical artery pH was 1.002 (95% confidence interval [CI], 0.997-1.007). Mean [standard deviation] umbilical artery pH was not different between the ephedrine 7.20 [0.10] and phenylephrine 7.22 [0.07] groups (mean difference -0.02, 95% CI of the difference -0.06 to 0.07; P = .38). Median (first, third quartiles) umbilical artery base excess was -3.4 mEq/L (-5.7 to -2.0 mEq/L) in the ephedrine group and -2.8 mEq/L (-4.6 to -2.2mEq/L) in the phenylephrine group (difference -0.6 mEq/L, 95% CI of the difference -1.6 to 0.3 mEq/L; P = .10). When adjusted for gestational age and infant gender, umbilical artery pH did not differ between groups. There were also no differences in the umbilical artery pH stratified by magnesium therapy or by the severity of preeclampsia.

CONCLUSIONS

We were unable to demonstrate a beneficial effect of phenylephrine on umbilical artery pH compared with ephedrine. Our findings suggest that phenylephrine may not have a clinically important advantage compared with ephedrine with regard to improved neonatal acid-base status when used to prevent spinal anesthesia-induced hypotension in women with preeclampsia undergoing cesarean delivery.

Intrathecal dexmedetomidine can decrease the 95% effective dose of bupivacaine in spinal anesthesia for cesarean section: A prospective, double-blinded, randomized study

BACKGROUND

Dexmedetomidine (Dex), as an adjuvant, has been reported to prolong the duration of spinal analgesia when adding to local anesthetic. We hypothesized that Dex could enhance the efficiency of intrathecal bupivacaine for spinal anesthesia in cesarean section. The aim of his study is to test our hypothesis that 5 μg Dex could enhance the efficiency of intrathecal bupivacaine and reduce the dose requirement of spinal bupivacaine for patients undergoing cesarean section.

METHODS

Ninety patients with ASA I or II, who underwent cesarean section, were randomized into 2 groups: group D (bupivacaine + 5 μg Dex) and group C (bupivacaine + the same volume of saline). The subsequent dose of spinal bupivacaine was determined by the improved up-down allocation method. The initial dose of bupivacaine in the 2 groups was 4 mg, and the subsequent dose for the following patient was depended on the probability of the current dose. ED95 of spinal bupivacaine was calculated using logistic regression model.

RESULTS

The ED95 and 95% confidence intervals (95% CI) of spinal hyperbaric bupivacaine in group D and group C were 7.4 mg (95% CI, 5.6-12.4 mg) and 11.0 mg (95% CI, 4.4-56.8 mg), respectively. The duration of sensory block was 120.5 ± 37.0 minutes in Dex group and 70.5 ± 34.5 minutes in Control group, respectively (P < .05). The duration of analgesia was 230.5 ± 40.5 minutes in Dex group and 145.1 ± 28.5 minutes in Control group, respectively (P < .001). The consumption of postoperative rescued sufentanil was significantly lower in Dex group than in the Control group (56.3 ± 9.4 vs 65.9 ± 10.7 μg). There was not significantly different in the patient satisfaction of analgesia, incidence of side effects, neonatal outcomes and neurological deficit between the 2 groups.

CONCLUSION

Intrathecal 5 μg Dex enhances the efficacy of spinal bupivacaine by 24% in patients undergoing cesarean section with spinal anesthesia. No additional side effect was observed by adding spinal Dex.

Prophylactic infusion of phenylephrine increases the median effective dose of intrathecal hyperbaric bupivacaine in cesarean section: A prospective randomized study

BACKGROUND

Phenylephrine infusion to prevent spinal-induced hypotension can attenuate cephalic spread of intrathecal bupivacaine. Therefore, we suspected the intrathecal dose requirement for bupivacaine may differ when using phenylephrine infusion to prevent spinal-induced hypotension in cesarean section. We designed a prospective, randomized study to determine the ED50 of hyperbaric bupivacaine for cesarean section under combined spinal-epidural anesthesia in healthy parturients with and without prophylactic phenylephrine infusion to prevent spinal-induced hypotension.

METHODS

Sixty healthy parturients rated American Society for Anesthesiology status I/II undergoing elective cesarean section were enrolled in this study, which was conducted July 2016 to February 2017 in the labor and delivery department of Jiaxing University Affiliated Women and Children Hospital. After enrollment, patients were randomized into 2 groups of 30 by blinded opaque envelopes sorted by computer-generated random allocation. Solutions were prepared by an anesthesiologist not involved in outcome measurement. Patients and anesthesiologists collecting data were blinded to group allocation. Group P (phenylephrine group) parturients received prophylactic infusion of phenylephrine at the time of intrathecal injection. Group S (saline group) parturients receive the same volume of saline. Doses of intrathecal bupivacaine for each patient were determined using an up-down allocation method; initial dose was 7 mg. Effective dose was defined as bilateral T6 or above sensory block level achieved within 10 minutes of intrathecal drug administration and no additional epidural lidocaine required for intraoperative pain. The Dixon and Massey formula was used to calculate ED50 values.

RESULTS

The ED50 values for hyperbaric bupivacaine were 7.0 mg (95% confidence interval [CI]: 6.6-7.4 mg) and 4.9 mg (95% CI: 4.4-5.4 mg) for groups P and S, respectively (P < .001). There were significant differences in incidence of hypotension and pH of umbilical arterial blood between groups S and P (60% vs 10%, P = .04 and 7.31 ± 0.04 vs 7.28 ± 0.06, P = .003, respectively).

CONCLUSION

The ED50 of intrathecal hyperbaric bupivacaine is higher when phenylephrine infusion is used to prevent spinal-induced hypotension than when it is not used.

The effect of intrathecal dexmedetomidine on the dose requirement of hyperbaric bupivacaine in spinal anaesthesia for caesarean section: a prospective, double-blinded, randomized study

Background

Studies have shown that dexmedetomidine (Dex) can prolong the duration of analgesia when added to local anaesthetic as an adjuvant in a central or peripheral nerve block. We hypothesized that intrathecal Dex can reduce the ED95 of spinal hyperbaric bupivacaine. Therefore, we conducted this prospective, double-blinded, randomized study to verify our hypothesis.

Methods

Ninety patients were allocated into the Dexmedetomidine group (received bupivacaine + 5 mcg dexmedetomidine) and the Control group (received bupivacaine + the same volume of saline) using a double-blinded and randomized method. The first patient in each group received 5 mg of IT hyperbaric bupivacaine, and the next dose for the following patient was determined by the probability of successful anaesthesia of the previous neighbouring dose. An improved up-down sequence allocated method combined with probit analysis was used to determine the ED95 of intrathecal hyperbaric bupivacaine for the two groups.

Results

The ED95 and 95% confidence intervals (95% CI) of IT hyperbaric bupivacaine of the Dex group and Control group were 8.4 mg (95% CI, 6.5~ 13.8 mg) and 12.1 mg (95% CI, 8.3~ 312.8 mg), respectively. The duration of sensory block was longer in the Dex group than in the Control group (110.3 ± 35.3 vs 67.5 ± 26.2). The duration of analgesia was also longer in the Dex group than in the Control group (224.9 ± 45.4 vs 155.1 ± 31.6). The consumption of postoperative rescued sufentanil was significantly higher in the Control group than in the Dex group.

Conclusion

Intrathecal 5 mcg dexmedetomidine potentiated hyperbaric bupivacaine antinociception by 31% in spinal anaesthesia for patients undergoing caesarean section.

Trial registration

We registered this study in a Chinese Clinical Trial Registry (ChiCTR) centre on Nov 1st 2016 and received the registration number: ChiCTR-IPR-16009699.

Comparing the Hemodynamic Effects of Spinal Anesthesia in Preeclamptic and Healthy Parturients During Cesarean Section

BACKGROUND

Despite controversies about the safest anesthetic technique for cesarean delivery in severely preeclamptic women, there is evidence that supports the use of spinal anesthesia in this group of patients.

OBJECTIVES

This prospective randomized clinical trial was designed to determine the hemodynamic effects of low-dose spinal bupivacaine and the incidence of spinal anesthesia-associated hypotension in severely preeclamptic and healthy parturients undergoing cesarean sections.

PATIENTS AND METHODS

Spinal anesthesia was performed with 10 mg (= 2 mL) hyperbaric 0.5% bupivacaine plus 2.5 µg sufentanil in two groups of patients after they received 500 mL of IV lactated Ringer's solution. Heart rate and blood pressure were recorded before spinal anesthesia and at two minutes intervals for 15 minutes after the block, and then every five minutes until the end of the surgery. Hypotension was defined as more than 25% of decline in the mean arterial blood pressure compared to the baseline in both groups (or systolic blood pressure < 100 mmHg in healthy parturients) and was treated with 5 mg IV ephedrine. The total amounts of intravenous administered fluid and the total doses of ephedrine were recorded for each patient as well.

RESULTS

The incidence rate of hypotension among the preeclamptic patients was lower than that of the healthy parturients, despite the former group receiving smaller volumes of intravenous fluids (P < 0.05). The total doses of IV ephedrine for treating hypotension were significantly lower among the preeclamptic patients (3.2 mg in preeclamptic patients versus 7.6 mg in normotensive patients) (P = 0.02). The one-minute Apgar score was significantly lower for the preeclamptic parturients (8.4 ± 0.7 versus 7.2 ± 1.5) (P = 0.001), but there was no significant difference in the five-minute Apgar scores between the two groups.

CONCLUSIONS

Our results confirm that low-dose bupivacaine spinal anesthesia is associated with a lower risk of hypotension than previously believed, and it can therefore be safely used in severe preeclamptic women undergoing cesarean delivery.