Randomized Double-blinded Comparison of Norepinephrine and Phenylephrine for Maintenance of Blood Pressure during Spinal Anesthesia for Cesarean Delivery

Determination of ED90s of Phenylephrine and Norepinephrine Infusion for Prevention of Spinal Anesthesia-Induced Hypotension in Patients with Preeclampsia During Cesarean Delivery

Background

Vasopressors remain an important strategy for managing spinal anesthesia-induced hypotension in women with preeclampsia. The aim of this study was to investigate the ED90s and efficacy ratio of phenylephrine and norepinephrine in managing spinal anesthesia-induced hypotension in women with preeclampsia during cesarean delivery.

Methods

60 women with preeclampsia, who underwent cesarean delivery, were randomly assigned to receive either a continuous intravenous infusion of phenylephrine or norepinephrine following spinal anesthesia. The initial dosage of phenylephrine or norepinephrine for the first women was 0.5 or 0.05 μg/kg/min, respectively, and subsequent infusion dosages were adjusted based on their efficacy in preventing spinal anesthesia-induced hypotension (defined as a systolic blood pressure less than 80% of the baseline level). The incremental or decremental doses of phenylephrine or norepinephrine were set at 0.1 or 0.01 μg/kg/min. The primary outcomes were the ED90s and efficacy ratio of phenylephrine and norepinephrine infusions for preventing spinal anesthesia-induced hypotension prior to delivery.

Results

The results obtained from isotonic regression analysis revealed that the ED90 values of the phenylephrine and norepinephrine group for preventing spinal anesthesia-induced hypotension were 0.597 (95% CI: 0.582-0.628) and 0.054 (95% CI: 0.053-0.056) μg/kg/min, respectively, with an efficacy ratio of 11.1:1. The results of Probit regression analysis revealed that the ED90 values were determined to be 0.665 (95% CI: 0.576-1.226) and 0.055 (95% CI: 0.047-0.109) μg/kg/min, respectively, with an efficacy ratio of 12.1:1.

Conclusion

The administration of 0.6 μg/kg/min phenylephrine and 0.05 μg/kg/min norepinephrine has been found to effectively manage a 90% incidence of spinal anesthesia-induced hypotension in women with preeclampsia.

Norepinephrine or phenylephrine for the prevention of post-spinal hypotension after caesarean section: A double-blinded, randomized, controlled study of fetal heart rate and fetal cardiac output

STUDY OBJECTIVE

Spinal anesthesia often causes hypotension, with consequent risk to the fetus. The use of vasopressor agents has been highly recommended for the prevention of spinal anesthesia-induced hypotension during caesarean delivery. Many studies have shown that norepinephrine can provide more stable maternal hemodynamics than phenylephrine. We therefore tested the hypothesis that norepinephrine preserves fetal circulation better than phenylephrine when used to treat maternal hypotension consequent to spinal anesthesia.

DESIGN

Prospective, randomized, double-blinded study.

SETTING

Operating room.

PATIENTS

We recruited 223 parturients with uncomplicated singleton pregnancies who were scheduled for elective caesarean section under combined spinal-epidural anesthesia.

INTERVENTIONS

The patients received prophylactic intravenous infusion of either 0.08 μg/kg/min norepinephrine or 0.5 μg/kg/min phenylephrine for prevention of spinal anesthesia-induced hypotension.

MEASUREMENTS

Changes in fetal heart rate and fetal cardiac output before and after spinal anesthesia were measured using noninvasive Doppler ultrasound.

MAIN RESULTS

90 subjects who received norepinephrine infusion and 93 subjects who received phenylephrine infusion were ultimately analyzed in the present study. The effects of norepinephrine and phenylephrine on the change of fetal heart rate and fetal cardiac output at 3 and 6 min after spinal block were similar. Although there was a statistically significant decrease in fetal cardiac output at 6 min after subarachnoid block initiation in both the norepinephrine group (mean difference 0.02 L/min; 95% CI, 0-0.04 L/min; P = 0.03) and the phenylephrine group (mean difference 0.02 L/min; 95% CI, 0-0.04 L/min; P = 0.02), it remained within the normal range.

CONCLUSIONS

Prophylactic infusion of comparable doses of phenylephrine or norepinephrine has similar effects on fetal heart rate and cardiac output changes after spinal anesthesia. Neither phenylephrine nor norepinephrine has meaningful detrimental effects on fetal circulation or neonatal outcomes.

Effect of pneumatic leg compression on phenylephrine dose for hypotension prophylaxis via variable rate infusion at cesarean delivery: an unblinded randomized controlled trial

BACKGROUND

Phenylephrine infusion is recommended to prevent spinal hypotension during cesarean delivery (CD) but may be associated with dose-dependent side effects. We hypothesized that adding intermittent pneumatic compression (IPC) of the lower legs to a variable-rate phenylephrine infusion will reduce the dose of phenylephrine required during CD.

METHODS

Seventy-six healthy women undergoing elective CD under combined spinal-epidural anesthesia were randomly assigned to IPC or control groups (n = 38 per group). After spinal anesthesia, IPC of the lower legs was initiated in the IPC group, and all women received a phenylephrine infusion starting at 25 μg·min-1 and increasing by 16.7 μg·min-1 for systolic blood pressure (SAP) < 90% baseline. If hypotension (SAP < 80% baseline) occurred, 100 μg phenylephrine bolus was administered. The primary outcome was the dose of phenylephrine per minute.

RESULTS

The dose of phenylephrine per minute (34.4 ± 7.3 μg·min-1 vs. 40.9 ± 9.5 μg·min-1, P = 0.001; mean difference -6.6 μg·min-1, 95% CI -10.5 to -2.7 μg·min-1) and the incidence of hypotension (24% vs. 55%, P = 0.005) were lower in the IPC group than in the control group. There were no significant differences between the two groups in the total dose of phenylephrine (603.2 ± 217.1 μg vs. 706.2 ± 247.5 μg, P = 0.058; mean difference -102.9 μg, 95% CI -209.4 to 3.5 μg), maternal side effects, or neonatal outcomes.

CONCLUSIONS

Intermittent pneumatic compression combined with a variable-rate phenylephrine infusion reduced the phenylephrine dose per minute and the incidence of hypotension during CD under spinal anesthesia.

Computer-controlled closed-loop norepinephrine infusion system for automated control of mean arterial pressure in dogs under isoflurane-induced hypotension: a feasibility study

Introduction

Intra-operative hypotension is a common complication of surgery under general anesthesia in dogs and humans. Computer-controlled closed-loop infusion systems of norepinephrine (NE) have been developed and clinically applied for automated optimization of arterial pressure (AP) and prevention of intra-operative hypotension in humans. This study aimed to develop a simple computer-controlled closed-loop infusion system of NE for the automated control of the mean arterial pressure (MAP) in dogs with isoflurane-induced hypotension and to validate the control of MAP by the developed system.

Methods

NE was administered via the cephalic vein, whereas MAP was measured invasively by placing a catheter in the dorsal pedal artery. The proportional-integral-derivative (PID) controller in the negative feedback loop of the developed system titrated the infusion rate of NE to maintain the MAP at the target value of 60 mmHg. The titration was updated every 2 s. The performance of the developed system was evaluated in six laboratory Beagle dogs under general anesthesia with isoflurane.

Results

In the six dogs, when the concentration [median (interquartile range)] of inhaled isoflurane was increased from 1.5 (1.5-1.5)% to 4 (4-4)% without activating the system, the MAP was lowered from 95 (91-99) to 41 (37-42) mmHg. In contrast, when the concentration was increased from 1.5 (1.0-1.5)% to 4 (4-4.8)% for a 30-min period and the system was simultaneously activated, the MAP was temporarily lowered from 92 (89-95) to 47 (43-49) mmHg but recovered to 58 (57-58) mmHg owing to the system-controlled infusion of NE. If the acceptable target range for MAP was defined as target MAP ±5 mmHg (55 ≤ MAP ≤65 mmHg), the percentage of time wherein the MAP was maintained within the acceptable range was 96 (89-100)% in the six dogs during the second half of the 30-min period (from 15 to 30 min after system activation). The median performance error, median absolute performance error, wobble, and divergence were - 2.9 (-4.7 to 1.9)%, 2.9 (2.0-4.7)%, 1.3 (0.8-1.8)%, and - 0.24 (-0.34 to -0.11)%·min-1, respectively. No adverse events were observed during the study period, and all dogs were extubated uneventfully.

Conclusion

This system was able to titrate the NE infusion rates in an accurate and stable manner to maintain the MAP within the predetermined target range in dogs with isoflurane-induced hypotension. This system can be a potential tool in daily clinical practice for the care of companion dogs.

Left-lateral position versus phenylephrine prophylactic treatment for hypotension following combined spinal epidural anesthesia during elective cesarean section

Backgroud

Hypotension is one of the most common and dangerous complications following combined spinal epidural anesthesia during elective cesarean delivery. Many methods are used to prevent or treat the hypotension with pharmacological or non-pharmacological measures. Our aim was to assess left-lateral position and phenylephrine prophylactic treatment for the prevention or treatment of maternal hypotension.

Methods

A total of 127 pregnant women were enrolled to be analyzed. The primary outcome measure was the incidence of maternal hypotension and secondary outcome measures included maternal demographic characteristics, anesthesia-to-incision time interval, birthweight and Apgar scores.

Results

The incidence of hypotension was 65.4 % in sequential reactive treatment and only 11.3 % achieved complete anesis after left-lateral position, significantly higher than 17.4 % in left-lateral position combined phenylephrine prophylactic treatment (P < 0.001). The increasing in gestational age may decrease the hypotension risk (P < 0.001). There were no significantly differences with maternal age, gravidity, parity, BMI before pregnancy, BMI before cesarean section, anesthesia-to-incision time interval, birthweight and Apgar scores (P > 0.05). The univariate logistic regression analysis revealed a significant association between treatment and hypotension (OR 0.11, 95 % CI 0.05-0.27). After adjusting for confounding variables, the risk of hypotension was decreased in subjects with treatment (OR 0.1, 95 % CI 0.04-0.25; OR 0.15, 95 % CI 0.05-0.43; OR 0.16, 95 % CI 0.05-0.46). The results of stratified and interaction analyses of the association between treatment revealed no interactive role from maternal age, gravidity and BMI before cesarean section (P > 0.05).

Conclusions

Single use of left-lateral position had limited effective and left-lateral position combined prophylactic phenylephrine used may be much better to prevent or treat hypetension, but larger studies with more robust data are needed to confirm these findings.

Is crystalloid co-loading necessary to prevent spinal hypotension during elective cesarean delivery? A randomized double-blind trial

BACKGROUND

Hypotension is common during spinal anesthesia for cesarean delivery. Preventive strategies include fluid loading and phenylephrine. We hypothesized that if prophylactic phenylephrine infusion is used, omission of fluid loading would be non-inferior to fluid co-loading in maintaining cardiac output. We assumed that if there was a difference, the increase in cardiac output would be greater in the no-loading than in the co-loading group.

METHODS

Term pregnant women scheduled for elective cesarean delivery were randomized to receive 1 L crystalloid co-loading or maintenance fluids only. Phenylephrine was titrated to maintain blood pressure. Changes in cardiac output following spinal anesthesia were the primary outcome. The study was powered as a non-inferiority trial, allowing the no-loading arm to have a 50% greater change in cardiac output. Heart rate, dose of phenylephrine, occurrence of nausea and vomiting, Apgar scores and neonatal acid base status were secondary outcomes.

RESULTS

Data from 63 women were analyzed. In contrast to our hypothesis, there was 33% less increase in cardiac output with no loading (ratio 0.67, 95% CI 0.15 to 1.36), and 60% greater reduction of cardiac output with no loading (ratio 1.6, 95% CI 1.0 to 2.7). Total dose of phenylephrine was higher in the no-loading group. There may be a less favorable neonatal acid base status without volume loading.

CONCLUSION

Omission of crystalloid co-loading leads to a decrease in cardiac output which has a potentially unfavorable impact on neonatal acid base status. We conclude that crystalloid co-loading may be useful in the presence of phenylephrine infusion.

Use of vasopressors to manage spinal anesthesia-induced hypotension during cesarean delivery

Cesarean sections are commonly performed under spinal anesthesia, which can lead to hypotension, adversely affecting maternal and fetal outcomes. Hypotension following spinal anesthesia is generally defined as a blood pressure of 80-90% below the baseline value. Various strategies have been implemented to reduce the incidence of spinal anesthesia-induced hypotension. The administration of vasopressors is a crucial method for preventing and treating hypotension. In the past decade, phenylephrine, a primarily alpha-adrenergic agonist, has been the preferred vasopressor for cesarean sections. Recently, norepinephrine, a potent alpha-agonist with modest beta-agonist activity, has gained popularity owing to its advantages over phenylephrine. Vasopressors can be administered via a bolus or continuous infusion. Although administering boluses alone is simpler in a clinical setting, continuous prophylactic infusion initiated immediately after spinal anesthesia is more effective in reducing the incidence of hypotension. Tailoring the infusion dose based on the patient's body weight and adjusting the rate in response to blood pressure changes, in addition to using a prophylactic or rescue bolus, helps reduce blood pressure variability during cesarean sections under spinal anesthesia until neonatal delivery.

Comparison of the effect of intravenous phenylephrine and norepinephrine boluses for post-spinal hypotension on neonatal outcome in elective caesarean section: A randomised controlled trial

Background and Aims

There is limited data on the effects of norepinephrine on neonatal outcomes and maternal complications relative to other vasopressors. The study aimed to compare neonatal outcomes and maternal complications after bolus intravenous doses of phenylephrine and norepinephrine for post-spinal hypotension in elective caesarean section women.

Methods

This randomised study was done on 100 elective caesarean section women under spinal anaesthesia. Block randomisation divided women into two groups to receive intravenous phenylephrine 50 μg bolus (Group A) or norepinephrine 5 μg bolus (Group B) following post-spinal hypotension. Groups were evaluated and compared for umbilical arterial blood gas analysis, birth weight, APGAR (appearance, pulse, grimace, activity, and respiration) score, maternal haemodynamics, and complications. Kolmogorov-Smirnov and Shapiro-Wilk tests were used to verify data normality. Independent samples t-test or Mann-Whitney U test was employed to compare continuous variables based on data normality, and the Chi-square test was used to determine categorical variable associations.

Results

Demographic characteristics of women were found to be comparable between groups. Umbilical arterial potential of hydrogen, partial pressure of oxygen, partial pressure of carbon dioxide, base excess, bicarbonate, birth weight, and APGAR scores were comparable across groups, showing no significant differences (P > 0.05). Groups had similar maternal haemodynamic characteristics and episodes of nausea, vomiting, and chest pain across groups without statistical significance (P > 0.05).

Conclusion

No notable distinction was found between neonatal outcomes and maternal complications between phenylephrine and norepinephrine bolus regimens. Norepinephrine can be used as an alternative to phenylephrine post-spinal hypotension in women undergoing elective caesarean section.

Norepinephrine versus phenylephrine on cerebral tissue oxygen saturation during prophylactic infusion to prevent spinal hypotension for Caesarean birth

BACKGROUND

Phenylephrine may cause a reduction in maternal cerebral tissue oxygen saturation (SctO2) during Caesarean birth to prevent spinal hypotension; however, the effect of norepinephrine has not been assessed. We hypothesized that norepinephrine was more effective than phenylephrine in maintaining SctO2 when preventing spinal hypotension during Caesarean birth.

METHODS

We conducted a randomized, double-blind, controlled study. Sixty patients were randomly assigned to prophylactic norepinephrine or phenylephrine to maintain blood pressure during spinal anesthesia for Caesarean birth. SctO2, systolic blood pressure, and heart rate were recorded. The primary outcome was the incidence of a 10% reduction of intraoperative SctO2 from baseline or more during Caesarean birth.

RESULTS

The norepinephrine group had a lower incidence of more than 10% reduction of intraoperative SctO2 from baseline than that of the phenylephrine group (13.3% vs 40.0%, P = .02). The change in SctO2 after 5 minutes of norepinephrine infusion was higher than that after phenylephrine infusion (-3.4 ± 4.7 vs -6.2 ± 5.6, P = .04). The change in SctO2 after 10 minutes of norepinephrine infusion was higher than that after phenylephrine infusion (-2.5 ± 4.4 vs -5.4 ± 4.6, P = .006). The norepinephrine group showed greater left- and right-SctO2 values than the phenylephrine group at 5 to 10 minutes. However, the change in systolic blood pressure was comparable between the 2 groups.

CONCLUSION

Norepinephrine was more effective than phenylephrine in maintaining SctO2 when preventing spinal hypotension during Caesarean birth. However, the changes in clinical outcomes caused by differences in SctO2 between the 2 medications warrant further studies.

Successful intraoperative management of laparoscopic hysterectomy in a patient with Eisenmenger syndrome: a case report

BACKGROUND

Patients with Eisenmenger syndrome (ES) requiring noncardiac surgery are at a significantly high risk of perioperative morbidity and mortality. However, perioperative management of patients with ES requiring laparoscopic surgery remains unclear.

CASE PRESENTATION

We describe the case of a patient with ES who underwent laparoscopic hysterectomy under general anesthesia with a peripheral nerve block. The objectives of the perioperative management included the following: (1) maintaining systemic vascular resistance and cardiac output through euvolemia, facilitated by the infusion of noradrenaline, and (2) preventing a reduction in oxygen-carrying capacity and factors that elevate pulmonary vascular resistance, such as pain, hypoxia, and decreased body temperature. Although laparoscopic procedures involved an increased risk in patients with ES, they are less invasive than open surgeries.

CONCLUSION

This report describes the successful anesthetic management of a patient with ES, ensuring a balance between systemic and pulmonary vascular resistance.

Randomized Double-Blinded Comparison of Intermittent Boluses Phenylephrine and Norepinephrine for the Treatment of Postspinal Hypotension in Patients with Severe Pre-Eclampsia During Cesarean Section

Background

Norepinephrine has fewer negative effects on heart rate (HR) and cardiac output (CO) for treating postspinal hypotension (PSH) compared with phenylephrine during cesarean section. However, it remains unclear whether fetuses from patients with severe pre-eclampsia could benefit from the superiority of CO. The objective of this study was to compare the safety and efficacy of intermittent intravenous boluses of phenylephrine and norepinephrine used in equipotent doses for treating postspinal hypotension in patients with severe pre-eclampsia during cesarean section.

Methods

A total of 80 patients with severe pre-eclampsia who developed PSH predelivery during cesarean section were included. Eligible patients were randomized at a 1:1 ratio to receive either phenylephrine or norepinephrine for treating PSH. The primary outcome was umbilical arterial pH. Secondary outcomes included other umbilical cord blood gas values, Apgar scores at 1 and 5 min, changes in hemodynamic parameters including CO, mean arterial pressure (MAP), HR, stroke volume (SV), and systemic vascular resistance (SVR), the number of vasopressor boluses required, and the incidence of bradycardia, hypertension, nausea, vomiting, and dizziness.

Results

No significant difference was observed in umbilical arterial pH between the phenylephrine and norepinephrine groups (7.303±0.38 vs 7.303±0.44, respectively; P=0.978). Compared with the phenylephrine group, the overall CO (P=0.009) and HR (P=0.015) were greater in the norepinephrine group. The median [IQR] total number of vasopressor boluses required was comparable between the two groups (2 [1 to 3] and 2 [1 to 3], respectively; P=0.942). No significant difference was found in Apgar scores or the incidence of maternal complications between groups.

Conclusion

A 60 µg bolus of phenylephrine and a 4.5 µg bolus of norepinephrine showed similar neonatal outcomes assessed by umbilical arterial pH and were equally effective when treating PSH during cesarean section in patients with severe pre-eclampsia. Norepinephrine provided a higher maternal CO and a lower incidence of bradycardia.

Comparative dose-response study on the infusion of norepinephrine combined with intravenous ondansetron versus placebo for preventing hypotension during spinal anesthesia for cesarean section: a randomised controlled trial

BACKGROUND

Ondansetron has been reported to attenuate the incidence of spinal anaesthesia-induced hypotension (SAIH) and norepinephrine requirement during caesarean section. However, no quantitative study has evaluated the extent of this effect. This study aimed to determine the dose-response of prophylactic infusion of norepinephrine to prevent SAIH in parturients who received intravenous ondansetron or placebo before spinal anaesthesia for caesarean section. The median effective dose (ED 50 ) and 90% effective dose (ED 90 ) were compared to evaluate the effect of ondansetron versus placebo on the norepinephrine requirement.

MATERIALS AND METHODS

One hundred fifty parturients undergoing caesarean section were randomized to receive either 0.1 mg/kg ondansetron (group O) or saline control (group C) 10 min before spinal anaesthesia. The parturients were randomly assigned to one of five different norepinephrine infusion groups: 0.02, 0.04, 0.06, 0.08 or 0.10 µg/kg/min. An effective infusion dose of norepinephrine was defined as non-occurrence of hypotension during the study period. The values for ED 50 and ED 90 of norepinephrine infusion were determined using probit regression. Differences between the two groups were evaluated by comparing the relative median potency with 95% CIs.

RESULTS

The ED 50 values were 0.033 (95% CIs, 0.024-0.043) µg/kg/min in group C and 0.021 (95% CIs, 0.013-0.029) µg/kg/min in group O. The ED 90 values were 0.091 (95% CIs 0.068-0.147) µg/kg/min in group C and 0.059 (95% CIs 0.044-0.089) µg/kg/min in group O, respectively. The estimate of the relative median potency for norepinephrine in group C versus group O was 0.643 (95% CIs, 0.363-0.956). The incidence of side effects was comparable between groups. No significant difference in neonatal outcomes.

CONCLUSION

Intravenous ondansetron 0.1 mg/kg before spinal anaesthesia significantly reduced the dose requirement of prophylactic norepinephrine infusion in parturients undergoing elective caesarean section. This finding is potentially useful for clinical practice and further research.

Comparison of Two Norepinephrine Rescue Bolus Doses for Management of Severe Post-Spinal Hypotension During Elective Caesarean Delivery: A Randomized, Controlled Trial

Background

Post-spinal hypotension is associated with maternal and neonatal complications; therefore, prompt control maternal blood pressure is necessary. In this study, we aimed to compare the efficacy and safety of two norepinephrine bolus doses in the rescue management of severe maternal hypotension during elective Cesarean delivery.

Methods

We included full-term pregnant women scheduled for Cesarean delivery under spinal anesthesia. Patients were randomized to receive either 5-mcg norepinephrine (n=79) or 10-mcg norepinephrine (n=79) for treatment of severe postspinal hypotension (systolic blood pressure ≤60% of baseline reading). The management of the hypotensive episode was considered successful if systolic blood pressure was >80% of the baseline within 2 mins of the bolus. The primary outcome was the incidence of successful management of severe post-spinal hypotension. Secondary outcomes included the incidence of reactive bradycardia, reactive hypertension, umbilical blood gases, and neonatal Apgar score at 5-min post-delivery.

Results

We included 73 patients in the 5-mcg group and 76 patients in the 10-mcg group into the final analysis. The incidence of successful management of severe hypotensive episodes was comparable between the two groups (43/73 [59%] and 46/76 [60%] in the 5-and 10-mcg group, respectively, P=0.917). The incidence of reactive hypertension, bradycardia, and neonatal outcomes were comparable between the two groups.

Conclusion

In mothers undergoing Cesarean delivery under spinal anesthesia, 10-mcg norepinephrine bolus was not superior to the 5-mcg bolus in the management of severe hypotension. Furthermore, the incidence of reactive bradycardia and hypertension was comparable in the two doses.

Clinical Trial Registration

NCT05290740, URL: https://clinicaltrials.gov/ct2/show/NCT05290740.

Prophylactic infusion of norepinephrine does not affect the rostral spread of spinal anesthesia in pregnancy: a prospective, randomized, double-blinded study

Background: The infusion of phenylephrine to prevent spinal-induced hypotension (SIH) in cesarean delivery may decrease the rostral spread of a spinal local anesthetic. We hypothesized that infusion of norepinephrine may decrease the rostral spread of spinal anesthesia, similar to that caused by phenylephrine. The aim of this study was to compare the block height of spinal anesthesia in the presence or absence of norepinephrine infusion administered to prevent SIH during cesarean delivery. Methods: Eighty patients were enrolled and allocated into groups receiving a norepinephrine infusion (group N) or saline infusion (group C). After intrathecal injection of hyperbaric bupivacaine 10 mg, the block height for cold and pinprick sensation was checked 10 and 20 min after the injection. The demographic characteristics, spinal anesthesia, side effects, and neonatal outcomes were also recorded. Results: The block height for cold and pinprick sensation was similar between the two groups, although the incidence of hypotension was significantly lower (p < 0.00) in group N than in group C. Systolic blood pressure was also more stable in group N than in group C, with the incidence of interventions being significantly lower in group N. There was no significant difference in patient satisfaction between the two groups. Conclusion: Evidence from this study suggested that prophylactic norepinephrine infusion does not reduce the rostral spread of spinal anesthesia in pregnancy. We suggest that it is not necessary to increase the dose of an intrathecal local anesthetic for cesarean delivery when prophylactic norepinephrine is administered. Clinical Trial Registration: https://www.chictr.org.cn/bin/project/edit?pid=152899, identifier [ChiCTR2200057439].

Micro- and macrocirculatory effects of norepinephrine on anaesthesia-induced hypotension: a prospective preliminary study

BACKGROUND

Intraoperative arterial hypotension (IOH) leads to increased postoperative morbidity. Norepinephrine is often use to treat IOH. The question regarding the mode of administration in either a bolus or continuous infusion remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a continuous infusion of norepinephrine to treat IOH.

METHODS

We conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video-capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissular CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a continuous infusion of 200 µg/h of norepinephrine. Time analysis for comparison between bolus and continuous infusion were at peak of MAP. The primary outcome was MFI by videocapillaroscopy.

RESULTS

Thirty-five patients were included, with 41 boluses and 33 continuous infusion. Bolus and continuous infusion induced an maximal increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, continuous infusion was associated with a smaller decrease in CO and stroke volume (p<0.05). For microcirculatory parameters, microvascular flow index (-0,1 vs. + 0,3, p=0,03), perfusion index (-12 vs. +12%, p=0,008), total vessel density (-0,2 vs. +2,3 mm2/mm2, p=0,002), showed significant opposite variations with bolus and continuous infusion, respectively.

CONCLUSIONS

These results on macro and microcirculation enlighten the potential benefits of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension.

TRIAL REGISTRATION

(NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204), 05/03/2018.

Norepinephrine boluses for the prevention of post-reperfusion syndrome in living donor liver transplantation: A prospective, open-label, single-arm feasibility trial

Background and Aims

Post-reperfusion syndrome (PRS) is a serious haemodynamic event during liver transplantation (LT), which increases early graft dysfunction and mortality. This study aimed to test the efficacy and safety of norepinephrine (NE) boluses to prevent PRS during orthotopic LT.

Methods

This feasibility phase II trial prospectively recruited a single arm of 40 patients undergoing living donor LT. The intervention was an escalated protocol of NE boluses starting at 20 µg. The primary outcome was the incidence of PRS. The secondary outcomes were arrhythmia, electrocardiographic (EKG) ischaemic changes, mean pulmonary pressure after reperfusion, 3-month survival and 1-year survival.

Results

PRS occurred in 28 (70%) cases [95% confidence interval (CI) 54% to 83%, P < 0.001], with a relative risk reduction of 0.22 when compared to our previous results (90%). Twelve cases developed transient EKG ischaemic changes. All EKG ischaemic changes returned to baseline after correction of hypotension. There was no significant arrhythmia or bradycardia (95% CI 0 to 0.9). After reperfusion, the mean pulmonary artery pressure was not significantly higher than the normal limit (20 mmHg) (P = 0.88). The 3-month survival was 0.95 (95% CI 0.83 to 0.99), and the 1-year survival was 0.93 (95% CI 0.8 to 0.98).

Conclusion

Our findings suggest that NE boluses starting with 20 μg is feasible and effective in lowering the risk of PRS during living donor LT. Additionally, NE boluses were not associated with significant myocardial ischaemic events, arrhythmia or a rise in pulmonary pressure.

A Randomized, Double-Blind, Graded Dose-Response Study of Norepinephrine Administration for Prevention of Post-Spinal Hypotension during Elective Cesarean Delivery

Norepinephrine has been recently introduced for prophylaxis against post-spinal hypotension during cesarean delivery; however, no data are available regarding its optimum dosing scheme. The primary objective of this study is to compare three different infusion and bolus dose combinations of norepinephrine for prophylaxis against post-spinal hypotension during cesarean delivery. This randomized, double-blind study was performed between February 2021 and May 2022. The study protocol was registered at Clinicaltrials.gov with the identification number NCT04701190. A total of 192 parturients were enrolled into this study. Patients were assigned to three groups-Zero-Bolus High-Infusion (Group ZBHI, 0 µg/0.1 µg kg-1 min-1, n = 61), Moderate-Bolus Moderate-Infusion (Group MBMI, 5 µg/0.075 µg kg-1 min-1, n = 61) and High-Bolus Low-Infusion (Group HBLI, 10 µg/0.05 µg kg-1 min-1, n = 61)-according to different combinations of norepinephrine infusion and bolus doses. All patients received spinal anesthesia with 10 mg hyperbaric bupivacaine plus 12.5 µg fentanyl. Immediately after cerebrospinal fluid was obtained, patients underwent a norepinephrine protocol corresponding to the randomized group. The primary outcome was the incidence of post-spinal hypotension. Secondary outcomes were post-delivery hypotension, frequency of post-spinal hypertension and bradycardia, and neonatal outcomes. The incidence of post-spinal hypotension was 11.7% in Group HBLI, 6.7% in Group ZBHI and 1.7% in Group MBMI (p = 0.1). The overall incidence of post-delivery hypotension in parturients was 41.1% (p = 0.797). The lowest frequency of post-spinal bradycardia (8.3%) and hypertension (11.7%) was seen in Group HBLI. The neonatal APGAR scores at 1st minute were higher in Group MBMI than in Group ZBHI (8.58 vs. 8.23, p = 0.001). All three infusion and bolus dose combinations of norepinephrine effectively reduced the incidence of post-spinal hypotension. However, high-dose bolus (10 µg) followed by low-dose infusion (0.05 µg kg-1 min-1) of norepinephrine can be preferred due to the reduced frequency of bradycardia and hypertension during cesarean delivery under spinal anesthesia.

Prophylactic intravenous norepinephrine for the prevention of hypotension during spinal anesthesia for elective cesarean section: a systematic review and dose-response meta-analysis of randomized controlled trials

Introduction: In this study, we aimed to evaluate the potential dose-response relationship between prophylactic norepinephrine (NE) infusion rates and the risks of hypotension during cesarean section following spinal anesthesia. Methods: Randomized controlled trials with two or more NE doses for post-spinal hypotension prophylaxis during cesarean section were systematically searched in the MEDLINE, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and US Clinical Trials Registry databases until 31 July 2022. The primary outcome was the relative risk of maternal hypotension with different NE regimens (infusion rates or bolus doses). Secondary outcomes included the relative risks of maternal and fetal adverse events with different NE regimens. Results: Ten studies with 1,144 parturients were included for final analysis using restricted cubic splines and random-effects dose-response meta-analysis models. A significant dose-response relationship existed between NE infusion rates and the relative risks of maternal hypotension. Every 0.01 μg/kg/min increment in the NE infusion rate was associated with a 14% decrease in the incidence of post-spinal hypotension. ED50 and ED95 of NE infusion rates for post-spinal hypotension prophylaxis were estimated to be 0.046 (95% CI from 0.032 to 0.085) and 0.2 (95% CI from 0.14 to 0.37) μg/kg/min, respectively. However, a higher NE infusion rate was associated with a higher incidence of maternal hypertension. Conclusion: An increased NE infusion rate was associated with a decreased incidence of post-spinal hypotension but an increased incidence of hypertension. Therefore, 0.07 μg/kg/min was recommended as the initial NE infusion rate for clinical practice, as it was associated with the lowest risk of physician intervention for unstable hemodynamics after spinal anesthesia for cesarean delivery. Systematic Review Registration: (https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=349934), identifier (CRD42022349934).

Society for Maternal-Fetal Medicine Consult Series #67: Maternal sepsis

Maternal sepsis is a significant cause of maternal morbidity and mortality, and is a potentially preventable cause of maternal death. This Consult aims to summarize what is known about sepsis and provide guidance for the management of sepsis during pregnancy and the postpartum period. Most studies cited are from the nonpregnant population, but where available, pregnancy data are included. The following are the Society for Maternal-Fetal Medicine recommendations: (1) we recommend that clinicians consider the diagnosis of sepsis in pregnant or postpartum patients with otherwise unexplained end-organ damage in the presence of a suspected or confirmed infectious process, regardless of the presence of fever (GRADE 1C); (2) we recommend that sepsis and septic shock in pregnancy be considered medical emergencies and that treatment and resuscitation begin immediately (Best Practice); (3) we recommend that hospitals and health systems use a performance improvement program for sepsis in pregnancy with sepsis screening tools and metrics (GRADE 1B); (4) we recommend that institutions develop their own procedures and protocols for the detection of maternal sepsis, avoiding the use of a single screening tool alone (GRADE 1B); (5) we recommend obtaining tests to evaluate for infectious and noninfectious causes of life-threatening organ dysfunction in pregnant and postpartum patients with possible sepsis (Best Practice); (6) we recommend that an evaluation for infectious causes in pregnant or postpartum patients in whom sepsis is suspected or identified includes appropriate microbiologic cultures, including blood, before starting antimicrobial therapy, as long as there are no substantial delays in timely administration of antibiotics (Best Practice); (7) we recommend obtaining a serum lactate level in pregnant or postpartum patients in whom sepsis is suspected or identified (GRADE 1B); (8) in pregnant or postpartum patients with septic shock or a high likelihood of sepsis, we recommend administration of empiric broad-spectrum antimicrobial therapy, ideally within 1 hour of recognition (GRADE 1C); (9) after a diagnosis of sepsis in pregnancy is made, we recommend rapid identification or exclusion of an anatomic source of infection and emergency source control when indicated (Best Practice); (10) we recommend early intravenous administration (within the first 3 hours) of 1 to 2 L of balanced crystalloid solutions in sepsis complicated by hypotension or suspected organ hypoperfusion (GRADE 1C); (11) we recommend the use of a balanced crystalloid solution as a first-line fluid for resuscitation in pregnant and postpartum patients with sepsis or septic shock (GRADE 1B); (12) we recommend against the use of starches or gelatin for resuscitation in pregnant and postpartum patients with sepsis or septic shock (GRADE 1A); (13) we recommend ongoing, detailed evaluation of the patient's response to fluid resuscitation guided by dynamic measures of preload (GRADE 1B); (14) we recommend the use of norepinephrine as the first-line vasopressor during pregnancy and the postpartum period with septic shock (GRADE 1C); (15) we suggest using intravenous corticosteroids in pregnant or postpartum patients with septic shock who continue to require vasopressor therapy (GRADE 2B); (16) because of an increased risk of venous thromboembolism in sepsis and septic shock, we recommend the use of pharmacologic venous thromboembolism prophylaxis in pregnant and postpartum patients in septic shock (GRADE 1B); (17) we suggest initiating insulin therapy at a glucose level >180 mg/dL in critically ill pregnant patients with sepsis (GRADE 2C); (18) if a uterine source for sepsis is suspected or confirmed, we recommend prompt delivery or evacuation of uterine contents to achieve source control, regardless of gestational age (GRADE 1C); and (19) because of an increased risk of physical, cognitive, and emotional problems in survivors of sepsis and septic shock, we recommend ongoing comprehensive support for pregnant and postpartum sepsis survivors and their families (Best Practice).

Prophylactic Fixed-Rate Phenylephrine Versus Norepinephrine Infusion in the Prevention of Post-spinal Anesthesia Hypotension During Cesarean Delivery

Background Maternal hypotension following spinal anesthesia can be actively countered by the use of vasopressors. Prophylactic infusion of vasopressors with a rescue bolus dosing was observed to be more effective for hemodynamic stability when compared to administering a bolus dose alone. Although phenylephrine is the recommended drug to treat spinal hypotension, many recent studies have focussed on the role of norepinephrine infusions during cesarean section. In this study, we compared prophylactic fixed-rate intravenous infusions of phenylephrine and norepinephrine during cesarean delivery under spinal anesthesia and the requirement of intraoperative provider-administered rescue bolus of phenylephrine needed to overcome post-spinal anesthesia hypotension. Methodology A total of 208 patients undergoing elective cesarean section under spinal anesthesia were randomly assigned to two groups (group P and group N). Group N included 104 patients who received norepinephrine infusion at a rate of 2.5 μg/minute (0.04 μg/kg/minute), and group P included 104 patients who received phenylephrine infusion at a rate of 50 μg/minute (0.8 μg/kg/minute) to treat spinal hypotension. The primary outcome of our study was to compare the reduction in the number and total dose of intraoperative provider-administered rescue bolus of phenylephrine needed to maintain systolic blood pressure. The secondary outcome of our study was to compare the neonatal outcome using umbilical venous blood gas sampling and Apgar score at one and five minutes. Results The total number of phenylephrine rescue bolus required to treat hypotension was significantly lower in group N (p = 0.0005) compared to group P. The neonatal outcome was similar between the two groups. Conclusions Prophylactic norepinephrine infusion when compared to prophylactic phenylephrine infusion is associated with a lesser requirement of rescue phenylephrine boluses.

Incidence of bradycardia during noradrenaline or phenylephrine bolus treatment of postspinal hypotension in cesarean delivery: A randomized double-blinded controlled trial

The treatment of choice for spinal anesthesia-induced hypotension during cesarean section is phenylephrine. As this vasopressor can cause reflex bradycardia, noradrenaline is a suggested alternative. This randomized double-blinded controlled trial included 76 parturients undergoing elective cesarean delivery under spinal anesthesia. Women received noradrenaline in bolus doses of 5 mcg or phenylephrine in bolus doses of 100 mcg. These drugs were used intermittently and therapeutically to maintain systolic blood pressure ≥ 90% of its baseline value. The primary study outcome was bradycardia incidence (<60 bpm) with intermittent bolus administration of these drugs. Secondary outcomes included extreme bradycardia (<40 bpm), number of bradycardia episodes, hypertension (systolic blood pressure > 120% of baseline value), and hypotension (systolic blood pressure < 90% of baseline value and requiring vasopressor use). Neonatal outcomes per the Apgar scale and umbilical cord blood gas analysis were also compared. The incidence of bradycardia in both groups (51.4% and 70.3%, respectively; p = 0.16) were not significantly different. No neonates had umbilical vein or artery pH values below 7.20. The noradrenaline group required more boluses than phenylephrine group (8 vs. 5; p = 0.01). There was no significant intergroup difference in any of the other secondary outcomes. When administered in intermittent bolus doses for the treatment of postspinal hypotension in elective cesarean delivery, noradrenaline, and phenylephrine have a similar incidence of bradycardia. When treating hypotension related to spinal anesthesia in obstetric cases, strong vasopressors are commonly administered, thought these can also have side effects. This trial assessed bradycardia after bolus administration of noradrenaline or phenylephrine, and found no difference in risk for clinically meaningful bradycardia.

Comparison of Prophylactic Infusion of Phenylephrine Versus Norepinephrine for the Prevention of Post Spinal Hypotension in Parturients Undergoing Elective Caesarean Section-a Randomized, Double-Blinded, Non-Inferiority Trial

Objective

Postspinal hypotension occurs in nearly 50% of women undergoing cesarean section (CS). Although phenylephrine (PE) is currently the vasopressor of choice, severe maternal bradycardia may adversely affect the fetal status due to the reduction in the maternal cardiac output. Norepinephrine (NE) is not associated with bradycardia and is now being evaluated for the treatment of post-spinal hypotension in obstetric patients. The hypothesis of this study was that the prophylactic NE infusion was non-inferior to PE infusion when used for the prevention of postspinal hypotension.

Methods

This was a randomized, double-blinded controlled study conducted in 130 parturients scheduled for CS. The participants received either prophylactic NE (5 μg min^-1) or PE (25 μg min^-1) infusion beginning at the time of spinal injection. The primary outcome was the incidence of hypotension in both groups. Maternal bradycardia, reactive hypertension, nausea and vomiting, requirement of rescue boluses of vasopressor and/or atropine, and neonatal acid base status were also recorded.

Results

The incidence of hypotension was 33.80% (22 of 65) in Group PE and 26.10% (17 of 65) in Group NE (P=0.85). The absolute risk difference [90% confidence interval (CI)] in the incidence of hypotension between the groups was -7.7% (-20.9, 5.4). The upper limit of the CI was less than the non-inferiority margin of 20%, indicating that the NE infusion was non-inferior to PE.

Conclusion

Prophylactic infusion of NE is not inferior to prophylactic PE infusion in the prevention of postspinal hypotension in patients undergoing CS.

Prophylactic Norepinephrine and Phenylephrine Boluses to Prevent Postspinal Anesthesia Hypotension During Cesarean Section: A Randomized Sequential Allocation Dose-Finding Study

Background

Norepinephrine and phenylephrine are widely used for obstetric anesthesia. Our central objective was to determine the ED (effective dose) 90 and potency ratio of prophylactic norepinephrine and phenylephrine boluses for preventing postspinal anesthesia hypotension during cesarean section.

Methods

Patients scheduled for elective cesarean section (n = 80) were randomly allocated to receive prophylactic norepinephrine (NE) or phenylephrine (PE) boluses immediately after induction of spinal anesthesia. An initial dose of NE (3 μg) and PE (37.5 μg) was given to the first patient, and an up-and-down sequential allocation method was used to determine the next dose level according to the responses (the effectiveness for preventing postspinal anesthesia hypotension [defined as SBP < 80% of baseline value]). Primary outcomes were ED90 and the potency ratio of prophylactic norepinephrine and phenylephrine boluses. Secondary outcomes were the incidence of postspinal anesthesia hypotension, severe postspinal anesthesia hypotension, nausea, vomiting, bradycardia, hypertension, umbilical artery blood gas values, and Apgar scores.

Results

The ED90 values for prophylactic norepinephrine and phenylephrine boluses were 8.0 μg (95% CI 7.1-11.0 μg) and 90.9 μg (95% CI 82.0-123.9 μg), respectively. The estimated relative potency ratio was 11.4:1. The incidence of bradycardia was lower in the NE group (2.5% vs 20%, P = 0.034). Other outcomes were comparable between the two groups.

Conclusion

An 8-μg prophylactic bolus of norepinephrine and a 90-μg prophylactic bolus of phenylephrine can effectively prevent postspinal anesthesia hypotension in patients during cesarean section.

Anesthesia during delivery in pregnant women with dilated cardiomyopathy

Emergency cesarean delivery in patients with heart failure increases maternal and fetal mortality. The present study aimed to identify the relationship between the use of anesthesia for delivery and progressive cardiac deterioration in women with dilated cardiomyopathy (DCM) and to examine its implications on maternal and fetal outcomes. Twenty-nine pregnancies in 25 women with DCM from the National Cerebral and Cardiovascular Center Hospital (Suita, Japan) were included in this retrospective longitudinal study. Fourteen of the patients (48.3%) delivered via cesarean section. Among these, 4 patients (13.8%) experienced heart failure within 42 days of delivery. The indication for cesarean delivery was heart failure in 3 patients and induction failure in 1 patient. The types of anesthesia used for these patients included general (n = 1), combined spinal-epidural (n = 2), and epidural (n = 1). Two of these cesarean deliveries were performed preterm. The left ventricular ejection fraction of patients with heart failure was ≤ 35% before 34 weeks gestation. Among the 25 patients without heart failure, 2 exhibited a left ventricular ejection fraction of ≤ 35% before 34 weeks gestation. Meanwhile, the types of anesthesia used for remaining 10 patients who did not experience heart failure included general (n = 1), combined spinal-epidural (n = 8), and epidural (n = 1). The rate of general anesthesia was 25% in patients who experienced heart failure and 4% in others. There was no incidence of maternal or fetal death. A preterm anesthetic evaluation may be warranted to optimize anesthetic management when the ejection fraction decreases to ≤ 35% before 34 weeks gestation in patients with DCM.

Manually Controlled, Continuous Infusion of Phenylephrine or Norepinephrine for Maintenance of Blood Pressure and Cardiac Output During Spinal Anesthesia for Cesarean Delivery: A Double-Blinded Randomized Study

BACKGROUND

To counteract the vasoplegia induced by spinal anesthesia (SA) and maintain blood pressure (BP) during cesarean delivery, phenylephrine is currently recommended, but norepinephrine might offer superior preservation of cardiac output. We aimed to compare the hemodynamic effects of phenylephrine and norepinephrine administered by manually adjusted continuous infusion during elective cesarean delivery.

METHODS

In this pragmatic, parallel-group, double-blind randomized controlled trial, 124 parturients scheduled for elective cesarean delivery under SA in a tertiary maternity in France, between February 2019 and December 2020, were randomized to receive norepinephrine at a starting rate of 0.05 μg·kg -1 ·min -1 (n = 62) or phenylephrine at a starting rate of 0.5 μg·kg -1 ·min -1 (n = 62). In both groups, the vasopressor infusion rate was then manually adjusted to maintain maternal systolic BP above 90% of the baseline value. The primary outcome, the change in cardiac index (CI) measured by thoracic bioreactance from SA to umbilical cord clamping, was analyzed through repeated measures analysis of variance and post hoc t tests. Secondary outcomes included maternal BP and neonatal outcomes.

RESULTS

In the norepinephrine group, cardiac index was maintained between 90% and 100% of baseline from SA to umbilical cord clamping, whereas it was maintained at significantly lower values (81%-88%) in the phenylephrine group ( P = .001). The percentage of elapsed time with a mean maternal BP <65 mm Hg and with systolic BP <80% of the baseline value was higher in the phenylephrine group: 2.9% (7.3) vs 0.5% (1.8) (absolute risk difference [ARD], -2.4%; 95% confidence interval, -4.4 to -0.5; P = .012) and 8.5% (16.6) vs 2.3% (5.2) (ARD, -6.2%; 95% confidence interval, -10.6 to -1.8; P = .006). Excluding parturients with gestational diabetes, severe neonatal hypoglycemia was more common in the phenylephrine group at 19.6% (9/46) vs 4.1% (2/49) ( P = .02). The other neonatal outcomes did not differ significantly between the groups.

CONCLUSIONS

When administered by manually adjusted infusion during SA for cesarean delivery, norepinephrine was associated with a higher CI; both infusions were effective for maintaining BP.

The use of epinephrine infusion for the prevention of spinal hypotension during Caesarean delivery: A randomized controlled dose-finding trial

BACKGROUND

This study aimed to compare three epinephrine doses for the prevention of spinal hypotension during Caesarean delivery.

METHODS

This randomized controlled trial included full-term pregnant women undergoing elective Caesarean delivery under spinal anesthesia. The participants received prophylactic epinephrine infusions at rates of 0.01, 0.02, or 0.03 mcg/kg/min. Spinal hypotension (systolic blood pressure <80% of baseline) was managed with a 9-mg ephedrine bolus. The primary outcome was the incidence of spinal hypotension. Secondary outcomes included total ephedrine requirement, the incidence of severe spinal hypotension, excessive tachycardia and hypertension, and neonatal outcomes.

RESULTS

The final analysis included 271 patients. The incidence of hypotension was lowest in the 0.03 mcg group (11/90 [12%]), followed by the 0.02 mcg (32/91 [35%]) and the 0.01 mcg (55/90 [61%]) groups (p < 0.001). The median ephedrine requirements (quartiles) were also the lowest in the 0.03 mcg group (0 [0-0] mg), followed by the 0.02 mcg (0 [0-9] mg) and the 0.01 mcg (9 [0-18] mg) groups. The incidence of severe hypotension was lower in the 0.03 mcg and 0.02 mcg groups than in the 0.01 mcg group (3/90 [3%], 5/91 [6%], and 15/90 [17%], respectively). The incidences of excessive tachycardia, hypertension, and neonatal outcomes were comparable among the groups.

CONCLUSION

The use of epinephrine to prevent spinal hypotension during Caesarean delivery is feasible and effective. An initial dose of 0.03 mcg/kg/min produced the lowest incidence of hypotension compared to 0.02 mcg/kg/min and 0.01 mcg/kg/min doses. The three doses were comparable in terms of the incidence of tachycardia, hypertension, and neonatal outcomes.

STUDY REGISTRATION

ClinicalTrials.gov Identifier: NCT05279703.

An updated "norepinephrine equivalent" score in intensive care as a marker of shock severity

Vasopressors and fluids are the cornerstones for the treatment of shock. The current international guidelines on shock recommend norepinephrine as the first-line vasopressor and vasopressin as the second-line vasopressor. In clinical practice, due to drug availability, local practice variations, special settings, and ongoing research, several alternative vasoconstrictors and adjuncts are used in the absence of precise equivalent doses. Norepinephrine equivalence (NEE) is frequently used in clinical trials to overcome this heterogeneity and describe vasopressor support in a standardized manner. NEE quantifies the total amount of vasopressors, considering the potency of each such agent, which typically includes catecholamines, derivatives, and vasopressin. Intensive care studies use NEE as an eligibility criterion and also an outcome measure. On the other hand, NEE has several pitfalls which clinicians should know, important the lack of conversion of novel vasopressors such as angiotensin II and also adjuncts such as methylene blue, including a lack of high-quality data to support the equation and validate its predictive performance in all types of critical care practice. This review describes the history of NEE and suggests an updated formula incorporating novel vasopressors and adjuncts.

Preventing Spinal Hypotension During Cesarean Birth With Two Initial Boluses of Norepinephrine in Chinese Parturients: A Randomized, Double-Blind, Controlled Trial

BACKGROUND

Norepinephrine is effective in preventing spinal hypotension during cesarean birth; however, an optimal regimen has not been determined. We hypothesized that an initial bolus of norepinephrine improves efficacy of spinal hypotension prophylaxis beyond continuous norepinephrine alone.

METHODS

In this double-blind, controlled study, 120 patients scheduled for cesarean birth under spinal anesthesia were randomly allocated to receive a norepinephrine bolus at 0.05 or 0.10 μg/kg, followed by norepinephrine infusion at a rate of 0.05 μg·kg -1 ·min -1 . The primary outcome was the frequency of spinal hypotension during cesarean birth. The doses of the rescue drug (phenylephrine), frequency of nausea or vomiting, duration of hypotension, frequency of intraoperative hypertension, frequency of bradycardia, and fetal outcomes were also compared.

RESULTS

One-hundred-fifteen patients were included in the analysis. Compared with the 0.05 μg/kg group, the frequency of spinal hypotension was lower in the 0.10 μg/kg group (20.7% vs 45.6%; odds ratio [OR], 0.31; 95% confidence interval (CI), 0.14-0.71; P = .004). Fewer rescue doses of phenylephrine (0 [0,0] vs 0 [0,80]; 95% CI for the difference, 0 (0-0); P = .006) were required, and the frequency of nausea or vomiting was lower (5.2% vs 17.5%; OR, 0.26; 95% CI, 0.07-0.99; P = .04) in the 0.10 μg/kg group. The duration of hypotension was shorter in the 0.10 μg/kg group than that in the 0.05 μg/kg group (0 [0,0] vs 0 [0,2]; 95% CI for the difference, 0 [0-0]; P = .006). The incidence of intraoperative hypertension, frequency of bradycardia, and fetal outcomes were comparable between the 2 groups.

CONCLUSIONS

With a fixed-rate norepinephrine infusion of 0.05 μg·kg -1 ·min -1 , the 0.10 μg/kg initial bolus was more effective in reducing the incidence of spinal hypotension compared with the 0.05 μg/kg initial bolus.

Consensus on the Southeast Asian management of hypotension using vasopressors and adjunct modalities during cesarean section under spinal anesthesia

BACKGROUND AND AIMS

This consensus statement presents a comprehensive and evidence-based set of guidelines that modify the general European or US guidelines for hypotension management with vasopressors during cesarean delivery. It is tailored to the Southeast Asian context in terms of local human and medical resources, health system capacity, and local values and preferences.

METHODS AND RESULTS

These guidelines were prepared using a methodological approach. Two principal sources were used to obtain the evidence: scientific evidence and opinion-based evidence. A team of five anesthesia experts from Vietnam, the Philippines, and Thailand came together to define relevant clinical questions; search for literature-based evidence using the MEDLINE, Scopus, Google Scholar, and Cochrane libraries; evaluate existing guidelines; and contextualize recommendations for the Southeast Asian region. Furthermore, a survey was developed and distributed among 183 practitioners in the captioned countries to gather representative opinions of the medical community and identify best practices for the management of hypotension with vasopressors during cesarean section under spinal anesthesia.

CONCLUSIONS

This consensus statement advocates proactive management of maternal hypotension during cesarean section after spinal anesthesia, which can be detrimental for both the mother and fetus, supports the choice of phenylephrine as a first-line vasopressor and offers a perspective on the use of prefilled syringes in the Southeast Asian region, where factors such as healthcare features, availability, patient safety, and cost should be considered.

Comparative efficacy and safety of prophylactic norepinephrine and phenylephrine in spinal anesthesia for cesarean section: A systematic review and meta-analysis with trial sequential analysis

Background: Phenylephrine is the first-line drug used to maintain blood pressure in cesarean delivery. However, it poses a high risk of bradycardia and depression of cardiac activity in pregnant women. Consequently, norepinephrine has gained popularity over the recent years, as an alternative to Phenylephrine because it is thought that prophylactic use of vasopressors may reduce the incidence of hypotension after spinal anesthesia. This systematic review compared the efficacy of both treatments.

Methods: We searched the following databases; CNKI, PubMed, Embase, Web of science, clinicaltrials.gov, Medline and Cochrane Library, for randomized controlled trials comparing the prophylactic efficacy of norepinephrine and phenylephrine on elective cesarean delivery under spinal anesthesia. The search period was from inception to July 2022, and the primary outcome indicator was incidence of bradycardia. Statistical analysis was conducted on Rev manager 5.4, and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework was used to evaluate the quality of evidence from each main finding.

Results: A total of 12 papers were included in the analysis. The incidence of bradycardia (RR = 0.37, 95% CI: 0.28 to 0.49, p &lt; 0.00001) and reactive hypertension (RR = 0.58, 95% CI 0.40 to 0.83, p = 0.003) was significantly lower in the norepinephrine (NE) group compared with the phenylephrine (PE) category. In contrast, there were no statistical differences in the umbilical cord blood gas analysis pH values between the groups (arterial: MD = 0.00, 95% CI −0.00 to 0.01, p = 0.22, vein: MD = 0.01, 95% CI −0.00 to 0.02, p = 0.06). The incidence of hypotension, nausea, and vomiting did not differ significantly between the NE and PE groups (hypotension: 23% vs. 18%; nausea: 14% vs. 18%; vomiting: 5% vs. 7%, respectively).

Conclusion: Prophylactic use of norepinephrine is safe and effective in maintaining maternal hemodynamics without causing adverse events to either the pregnant woman or fetus.

Systematic Review Registration: website https://www.crd.york.ac.uk/prospero/, identifier CRD42022347095

Malign asitli over kanserinde sitoredüktif cerrahide perioperatif hemodinamik optimizasyon

Purpose: In this study, we aimed to evaluate the effects of norepinephrine and albumin use in patients with epithelial ovarian cancer with malignant ascite in order to maintain plasma oncotic pressure and intravascular volume, to provide perioperative hemodynamic stabilization and tissue perfusion. In addition, it was aimed to compare in terms of postoperative intensive care admission, hospital stay and complications. Materials and Methods: A total of 66 patients, 38 with ascites and 28 without ascites, who underwent cytoreductive surgery for ovarian cancer were included in this study. PVI and invasive arterial monitoring of the patients were performed after hemodynamic stabilization (after the start of surgery) (T0). T0, 1st hour (T1) and 2nd hour (T2) and postoperative (Tpostop.) Ascites patients were composed of 3 subgroups which the ones received norepinephrine (NE) infusion, norepinephrine + albumin (NEA) infusion or only fluid therapy (FT). From the perioperative hemodynamic and laboratory data of the patients, tissue perfusion was evaluated with lactate, and hemodynamic status was evaluated with pleth variability index (PVI), perfusion index (PI) and mean arterial pressure (MAP). Results: Demographic and clinical findings did not differ significantly between patients with and without ascites. Lactate level in NEA / NE group in Tpostop, PVI level in T1h, T2h and Tpostop time frames were determined higher than the FT group. PI was found to be significantly lower in the T2 time frame. The postoperative ICU admission rate was higher in the NEA and NE groups. The duration of ICU stay in group NEA was shorter than in group NE. Conclusion: We recommend the use of low-dose NE with albumin to provide perioperative hemodynamic optimization, tissue perfusion and plasma oncotic pressure in surgery of ovarian cancer with malignant ascites. Despite high fluid replacement in these patients, the use of norepinephrine and albumin together may have an important role in preventing / reducing major complications in the perioperative period.

Effect of Weight-Adjusted Phenylephrine, Norepinephrine, and Metaraminol for Elective Cesarean Delivery on Neonatal Acid–Base Status: A Randomized Controlled Trial

Purpose

Many previous trials have compared the effects of different vasoactive drugs on cesarean section patients, but their infusion rate is based on experience rather than high-quality evidence. It is difficult to judge whether the effect of vasoactive drug comes from the better choice or a more appropriate at rates of vasoactive drugs. The effect of vasoactive drugs at the rates of the 90% effective dose needs to be verified and compared.

Patients and Methods

Women undergoing elective caesarean delivery under combined spinal-epidural anaesthesia were randomized to receive phenylephrine or norepinephrine or metaraminol infusion at the rate that was assumed to be the 90% effective dose. Anesthetic management was standardized and included fluid loading with 10 mL/kg of Ringer. The primary outcome was the umbilical artery pH.

Results

78 patients were included. The umbilical artery pH was not significantly different among the three groups (phenylephrine group: 7.33 ± 0.03 vs norepinephrine group: 7.33 ± 0.04 vs metaraminol group: 7.33 ± 0.04, P = 0.99). There were no significant differences in the incidence of hypotension, hypertension, bradycardia, and nausea and vomiting among the three groups. The SBP of the phenylephrine group was significantly higher than that of the metaraminol group (adjustive P value = 0.005).

Conclusion

Phenylephrine (0.54 μg/kg/min) or metaraminol (2 μg/kg/min) or norepinephrine (0.08 μg/kg/min) administered to healthy patients with elective cesarean section after spinal anesthesia has no significant effect on the acid-base balance of the fetus.

Analgesic effect of ultrasound-guided erector spinae plane block (espb) in general anesthesia for cesarean section: a randomized controlled trial

Background

The analgesic effects of erector spinae plane block in general anesthesia for cesarean section and recovery from puerperae remain unclear.

Methods

Sixty patients with contraindications for spinal anesthesia who required general anesthesia for cesarean section were enrolled and randomly divided into the erector spinal plane block (ESPB) combined with the general anesthesia group (group E) and general anesthesia group (group G). Group E received bilateral ESPB (20 ml of 0.25% ropivacaine on each side) under ultrasound guidance 30 min before general anesthesia. The primary outcomes were the number of patient-controlled intravenous analgesia (PCIA) boluses, and Bruggemann comfort scale (BCS) scores at 2 h, 6 h, 12 h, and 24 h after operation. The second outcome was intraoperative anesthesia dosage, fetal delivery time, puerperae emergence time, visual analog scale (VAS) at 2 h, 6 h, 12 h, and 24 h after operation, and incidence of nausea and vomiting. Heart rate (HR) and mean arterial pressure (MAP) were recorded 10 min before the start of anesthesia (T0), at the induction of anesthesia (T1), at skin incision (T2), and fetal delivery (T3), and immediately after surgery (T4).

Results

The number of PCIA boluses was lower in group E than in group G (P < 0.001). The BCS score increased at 2 h and 6 h after the operation in group E (P < 0.05), while the VAS score significantly decreased in group E at the same time (P < 0.05). Compared with group G, the doses of propofol and remifentanil were significantly decreased in group E (P < 0.001), the emergence time of puerperae was shortened (P = 0.003), and the incidence of nausea and vomiting was significantly decreased (P = 0.014).

Conclusion

Ultrasound-guided ESPB applied to general anesthesia for a cesarean section can significantly reduce the required dose of general anesthetic drugs, shorten the recovery time of the puerperae, and improve postoperative analgesia.

Trial registration:www.clinicaltrials.gov under the number ChiCTR2200056337 (04–02-2022).

Comparative Dose–Response Study on the Infusion of Norepinephrine Combined with Crystalloid Coload versus Colloid Coload for Preventing Hypotension During Spinal Anesthesia for Cesarean Delivery

Background

Although the optimal infusion dose of norepinephrine combined with crystalloid coload for preventing spinal anesthesia-induced hypotension (SAIH) for cesarean delivery has been established, the infusion regimen of norepinephrine combined with colloid coload has not been fully quantified. The objective of this study was to compare and determine the median effective dose (ED₅₀) and 90% effective dose (ED₉₀) of norepinephrine infusion combined with crystalloid coload versus colloid coload for preventing SAIH during cesarean delivery.

Methods

Two hundred parturients were randomly assigned to receive norepinephrine infusion at 0.02, 0.04, 0.06, 0.08, or 0.10 µg/kg/min in combination with 10 mL/kg crystalloid coload or colloid coload to prevent SAIH. The study period was defined as the interval from the commencement of intrathecal injection to delivery of the neonate. The primary outcome was non-occurrence of hypotension, defined as systolic blood pressure (SBP) less than 80% of the baseline before delivery. The ED₅₀ and ED₉₀ of norepinephrine infusion dose were determined using probit regression analysis. By calculating the 95% confidence intervals (CIs) of relative median potency to determine whether the prophylactic infusion of norepinephrine requirement was different between the two groups.

Results

The derived ED₅₀ and ED₉₀ of norepinephrine infusion combined with crystalloid coload were 0.030 (95% CIs 0.020 to 0.038) and 0.097 (95% CIs 0.072 to 0.157) µg/kg/min, respectively. The ED₅₀ and ED₉₀ of norepinephrine infusion combined with colloid coload were 0.021 (95% CIs 0.013 to 0.029) and 0.070 (95% CIs 0.053 to 0.107) µg/kg/min, respectively. The estimate of relative median potency for norepinephrine between the two groups was 1.37 (95% CIs 0.94 to 2.23).

Conclusion

Under the conditions of this study, 10 mL/kg colloid coload reduced the dose of prophylactic norepinephrine infusion by approximately 30% in parturients during spinal anesthesia for cesarean delivery compared with the crystalloid coload.

Determination of the Relative Potency of Norepinephrine and Phenylephrine Given as Infusions for Preventing Hypotension During Combined Spinal-Epidural Anesthesia for Cesarean Delivery: A Randomized Up-And-Down Sequential Allocation Study

Purpose: The relative potency of norepinephrine and phenylephrine given as boluses to treat hypotension during spinal anesthesia for cesarean delivery has been reported but few data are available for infusions. This study aimed to determine the relative potency of norepinephrine and phenylephrine when given by infusion for preventing hypotension during combined spinal-epidural anesthesia for cesarean delivery.

Methods: This was a prospective, randomized, double-blind, up-and-down sequential allocation study. Patients were randomly allocated to receive a prophylactic infusion of norepinephrine or phenylephrine started immediately after induction of anesthesia. The first patients received either norepinephrine 0.1 μg/kg/min or phenylephrine 0.5 μg/kg/min. An effective infusion rate was defined when no hypotension occurred before delivery. For each subsequent patient, the norepinephrine infusion rate was decreased or increased by 0.01 μg/kg/min or the phenylephrine infusion rate was decreased or increased by 0.05 μg/kg/min according to whether the infusion was effective or ineffective respectively in the previous patient. Values for the infusion rate that was effective in preventing hypotension in 50% of patients (ED50) for norepinephrine and phenylephrine were estimated using up-and-down sequential analysis and relative potency was estimated. Probit regression was used as a backup and sensitivity analysis.

Results: The ED50 values for norepinephrine and phenylephrine calculated by the up-and-down method were 0.061 (95% CI 0.054–0.068) μg/kg/min and 0.368 (95% CI 0.343–0.393) μg/kg/min respectively. The estimated relative potency ratio for ED50 for norepinephrine to phenylephrine was 6.03:1 (95% CI 5.26:1 to 6.98:1).

Conclusion: Under the conditions of this study, norepinephrine given by infusion was about 6 times more potent than phenylephrine. This information is useful for clinical practice and further comparative studies of norepinephrine versus phenylephrine.

Clinical Trial Registration:http://www.chictr.org.cn/showproj.aspx, identifier [ChiCTR2200056237]

A Height-Based Dosing Algorithm of Bupivacaine in Spinal Anesthesia for Decreasing Maternal Hypotension in Cesarean Section Without Prophylactic Fluid Preloading and Vasopressors: A Randomized-Controlled Non-Inferiority Trial

Background

There is a high incidence of maternal hypotension in spinal anesthesia for cesarean section. The aim of the study is to investigate whether there is a height-based dosing algorithm of bupivacaine that provides adequate anesthesia with less maternal hypotension.

Methods

There were 2 groups of 280 parturients who did not receive prophylactic fluid preloading: Test and Conventional group. In Test group, a height based dosing algorithm was used to confirm the dose of bupivacaine in parturients without prophylactic vasopressors. In the Conventional group, a constant dose of bupivacaine was used. The complications and quality of anesthesia were evaluated.

Results

In the Conventional group, the shorter participants had higher incidence of hypotension, faster sensory block time, and more participants with complete motor block (p = 0.030, 2.957 × 10^-14, and 0.012). In the Test group, the incidence of hypotension, sensory block time, and number of participants with complete motor block did not change with height (p = 0.199, 0.617, and 0.209). The height-based dosing algorithm of bupivacaine decreased the incidence of hypotension (p = 0.004), induced lower sensory block level and less degree of motor block (p = 3.513 × 10^-7 and 5.711 × 10^-11). The quality of analgesia, quality of muscle relaxation, and degree of intraoperative comfort were similar in both groups (p = 0.065, 0.498, and 0.483).

Conclusions

The height influences the dose of bupivacaine in spinal anesthesia; without prophylactic fluid pre-loading and vasopressors, the height-based dosing algorithm of bupivacaine is suitable, and meets the cesarean section' requirement with less maternal hypotension.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier: NCT03497364.

Spinal hypotension in obstetrics: Context-sensitive prevention and management

Spinal hypotension during caesarean section remains a common complication, with important attendant maternal and fetal adverse outcomes. Research elucidating the mechanisms of spinal hypotension has led to the development and refinement of effective management strategies, with a particular emphasis on prophylactic vasopressor administration. This has proved effective in well-resourced settings, with maternal comfort and the elimination of nausea now considered the primary aim of treatment. In resource-limited settings, sophisticated strategies are not feasible due to insufficient equipment, staff, and expertise. Therefore, in these areas spinal hypotension remains an important cause of maternal and fetal morbidity and mortality. Translational, context-sensitive research in resource-limited settings has shown promise in implementing pragmatic strategies based on research from resource-rich environments. We review the current best practice for the prevention and treatment of spinal hypotension, with a special emphasis on effective strategies in resource-limited settings. We further suggest a research agenda to address the knowledge gap in specific contexts.

Comparison of Metaraminol, Phenylephrine, and Norepinephrine Infusion for Prevention of Hypotension During Combined Spinal-Epidural Anaesthesia for Elective Caesarean Section: A Three-Arm, Randomized, Double-Blind, Non-Inferiority Trial

BACKGROUND

A direct comparison of phenylephrine, metaraminol, and norepinephrine in preventing hypotension during spinal anaesthesia for elective caesarean section has never been made.

PATIENTS AND METHODS

Seventy-five parturients scheduled for elective caesarean section were randomly assigned into the three groups. After spinal anaesthesia induction, patients received a bonus dose of vasopressor (norepinephrine 4ug, phenylephrine 50ug, or metaraminol 250ug) combined with continuous infusion (norepinephrine 8ug/mL, phenylephrine 100ug/mL, or metaraminol 500ug/mL) at a rate of 30 mL/h to prevent hypotension. The primary outcome was umbilical arterial (UA) pH and other intraoperative data were also recorded.

RESULTS

The UA pH was 7.32±0.03 for metaraminol, 7.31±0.03 for phenylephrine, and 7.31±0.03 for norepinephrine. The 95% CI of MD was -0.011 to 0.026 comparing metaraminol with norepinephrine and 0.0181 to 0.0182 comparing phenylephrine with norepinephrine. Both lower bounds of the 95% CI of MD were above the predetermined lower boundary of clinical non-inferiority of -0.03, indicating both metaraminol and phenylephrine were non-inferior to norepinephrine. Moreover, the incidence of hypotension was lower in metaraminol compared with norepinephrine (P = 0.01). However, the incidence of hypertension was significantly lower in both phenylephrine and metaraminol compared with norepinephrine.

CONCLUSION

Both metaraminol and phenylephrine were non-inferior to norepinephrine with respect to neonatal UA pH when used as a bolus and continuous infusion to prevent hypotension during combined spinal-epidural anaesthesia for elective caesarean section.

Neurodevelopmental effects of maternal blood pressure management with noradrenaline during general anaesthesia for nonobstetric surgery in the pregnant rabbit model

BACKGROUND

In pregnant women, anaesthesia-induced hypotension is commonly treated using phenylephrine or noradrenaline, the rationale being to maintain uterine perfusion pressure and thereby uterine blood flow. Evidence for this strategy during general anaesthesia for nonobstetric surgery is absent.

OBJECTIVE

To analyse the effects of treating anaesthesia-induced hypotension with noradrenaline on brain development of rabbit foetuses of mothers subjected to general anaesthesia for nonobstetric surgery. We hypothesised that treatment of maternal hypotension would improve foetal outcomes.

DESIGN

Randomised controlled laboratory study using 21 pregnant rabbits (does) at 28 days of gestation.

INTERVENTION

Two hours of sevoflurane anaesthesia for a laparotomy without treatment of anaesthesia-induced hypotension (hypotension group) or with maintaining maternal mean arterial pressure above 80% of the awake value using noradrenaline (noradrenaline group). In the control group, does remained untouched. At term, all pups were delivered by caesarean section. One day later, the neurobehaviour of the pups was assessed and brains were harvested.

MAIN OUTCOMES

Neuron density in the frontal cortex for the comparison of noradrenaline groups versus hypotension groups was the primary outcome; the neurobehavioural scores and other histological outcomes were secondary outcomes.

RESULTS

In the noradrenaline groups and hypotension groups, neuron density in the frontal cortex was similar (1181 ± 162 versus 1189 ± 200 neurons mm-2, P = 0.870). However, significantly less foetal survival, lower sensory scores in neurobehavioural assessment and less proliferation were observed in the noradrenaline group when compared with the hypotension group. Neuron densities in other regions, total cell densities, biometrics and synaptogenesis were not affected. There were no differences between the control group and hypotension group.

CONCLUSION

During general anaesthesia for nonobstetric surgery in rabbits, treatment of anaesthesia-induced hypotension using noradrenaline did not affect neuron densities but was associated with impaired foetal outcomes according to several secondary outcome parameters. Further studies are needed to investigate any clinical relevance and to determine the target blood pressure in pregnant women during general anaesthesia.

Comparison of Prophylactic Norepinephrine and Phenylephrine Infusions During Spinal Anaesthesia for Primary Caesarean Delivery in Twin Pregnancies: A Randomized Double-Blinded Clinical Study

Background

Norepinephrine has been associated with improved heart rate (HR) and cardiac output (CO) compared to phenylephrine as a treatment for post-spinal hypotension during caesarean delivery (CD) in singleton pregnancies. Our current study compared the effects of norepinephrine and phenylephrine in maintaining maternal hemodynamics after spinal anaesthesia in twin pregnancies during elective CD.

Methods

This was a double-blinded, randomized, controlled study. From December 2017 to December 2018, 62 women with healthy twin term pregnancies undergoing elective CD under spinal anaesthesia were studied. Following spinal induction, either norepinephrine (6 μg/mL) or phenylepinephrine (75 μg/mL) was infused at 60 mL/h to maintain systolic blood pressure (SBP) near baseline until delivery. HR, SBP, systemic vascular resistance (SVR), and CO were collected using anaesthesia monitors and continuous-pulse waveform analysis. The primary outcome was maternal CO. Other parameters of maternal hemodynamics, umbilical cord blood gases, and adverse events were also compared.

Results

Hemodynamic variables (CO, SBP, HR, and SVR) between spinal anaesthesia induction to skin incision were similar between the two groups (P = 0.889, 0.057, 0.977, and 0.416, respectively). The incidence of bradycardia was significantly higher in the phenylephrine group (69%) than in the norepinephrine group (24.2%, P<0.001). Maternal nausea and vomiting, hypotension, reactive hypertension, and neonatal outcomes did not differ between the groups.

Conclusion

When administered as a prophylactic fixed-rate infusion, phenylephrine and norepinephrine are both capable of maintaining maternal blood pressure following spinal anaesthesia in twin pregnancies. There were no differences in the maternal hemodynamics or foetal outcomes between women receiving norepinephrine and phenylephrine.

Previous Presentations

Presented at the 51st Society for Obstetric Anesthesia and Perinatology Annual Meeting, Phoenix, Arizona, May 1–5, 2019.

Clinical Trial Number and Registry

No. ChiCTR-IOR-17013358.

Norepinephrine versus phenylephrine infusion for preventing postspinal hypotension during cesarean section for twin pregnancy: a double-blinded randomized controlled clinical trial

Background

Compared with singleton pregnancy, twin gestation is featured by a greater increase in cardiac output. Therefore, norepinephrine might be more suitable than phenylephrine for maintaining blood pressure during cesarean section for twins, as phenylephrine causes reflex bradycardia and a resultant decrease in cardiac output. This study was to determine whether norepinephrine was superior to phenylephrine in maintaining maternal hemodynamics during cesarean section for twins.

Methods

Informed consent was obtained from all the patients before enrollment. In this double-blinded, randomized clinical trial, 100 parturients with twin gestation undergoing cesarean section with spinal anesthesia were randomized to receive prophylactic norepinephrine (3.2 μg/min) or phenylephrine infusion (40 μg/min). The primary outcome was the change of heart rate and blood pressure during the study period. The secondary outcomes were to compare maternal complications, neonatal outcomes, Apgar scores and umbilical blood acid-base status between the two vasopressors.

Results

There was no significant difference observed for the change of heart rate between two vasopressors. The mean standardized area under the curve of heart rate was 78 ± 12 with norepinephrine vs. 74 ± 11 beats/min with phenylephrine (mean difference 4.4, 95%CI − 0.1 to 9.0; P = .0567). The mean standardized area under the curve of systolic blood pressure (SBP) was significantly lower in parturients with norepinephrine, as the mean of differences in standardized AUC of SBP was 6 mmHg, with a 95% CI from 2 to 9 mmHg (P = .0013). However, requirements of physician interventions for correcting maternal hemodynamical abnormalities (temporary cessation of vasopressor infusion for reactive hypertension, rescuing vasopressor bolus for hypotension and atropine for heart rate less < 50 beats/min) and neonatal outcomes were also not significantly different between two vasopressors.

Conclusion

Infusion of norepinephrine was not associated with less overall decrease in heart rate during cesarean section for twins, compared with phenylephrine.

Trial registration

Chinese Clinical Trial Registry (ChiCTR1900021281).