A Comparative Study of Bolus Norepinephrine, Phenylephrine, and Ephedrine for the Treatment of Maternal Hypotension in Parturients with Preeclampsia During Cesarean Delivery Under Spinal Anesthesia

Comparison of vasopressors for management of hypotension in high-risk caesarean section under neuraxial anesthesia: a systematic review and network meta-analysis

BACKGROUND

Vasopressors are effective in managing perioperative hypotension in high-risk parturients undergoing Caesarean section (CS). Nevertheless, the optimal vasopressor for addressing hypotension induced by neuraxial anesthesia remains a subject of investigation.

METHODS

We compared hypotension episodes among high-risk parturients who received ephedrine, noradrenaline, or phenylephrine by searching four electronic databases and reviewing the relevant references. Inclusion criteria encompassed randomized controlled trials directly comparing two or more vasopressors in the context of managing hypotension in high-risk parturients undergoing neuraxial anesthesia for CS. A network meta-analysis was performed using fixed-effects and Bayesian random-effects models.

RESULTS

We analyzed 13 trials involving 1,262 patients. While our direct and indirect comparisons revealed no reveal statistically significant differences in the number of hypotensive episodes among patients treated with different vasopressors, vasopressors were hierarchically ranked. Phenylephrine (Rank of the best choice = 0.81) exhibited the highest effectiveness in preventing hypotension, followed by ephedrine (Rank of the best choice = 0.10) and noradrenaline (Rank of the best choice = 0.09). Bradycardia occurrence was higher in patients administered phenylephrine compared to those given noradrenaline (risk ratio [RR]: 0.23; 95% confidence interval [CI]: 0.03 to 0.85) or ephedrine (RR: 0.01; 95% CI: 0.00 to 0.12). Notably, patients treated with phenylephrine or noradrenaline experienced reduced occurrences of nausea or vomiting compared to those who received ephedrine (RR: 0.37; 95% CI: 0.19 to 0.59 for phenylephrine and RR: 0.28; 95% CI: 0.10 to 0.75 for noradrenaline). Regarding fetal outcomes, no significant differences were noted between noradrenaline and phenylephrine. Overall norepinephrine in maternal outcomes may be more favorable.

CONCLUSIONS

Our findings suggest the potential advantages of phenylephrine for reducing hypotensive episodes in high-risk parturients undergoing CS. Noradrenalin may emerge as an alternative, particularly for women at high risk of caesarean delivery.

TRIAL REGISTRATION

This systematic review was registered at PROSPERO (CRD42023397259).

Efficacy and safety of norepinephrine versus phenylephrine for post-spinal hypotension in preeclamptic patients: A systematic review and meta-analysis

OBJECTIVE

We conducted a systematic review and meta-analysis to evaluate the fetomaternal outcomes after the administration of norepinephrine or phenylephrine for the treatment of post spinal hypotension in preeclamptic women undergoing a cesarean section.

DATA SOURCES

We searched on PubMed, Embase, Scopus, Cochrane CENTRAL, and clinicaltrials.gov from inception till June 2024.

STUDY SELECTION

Randomized controlled trials of preeclamptic women receiving norepinephrine or phenylephrine for post spinal hypotension were included.

DATA EXTRACTION AND SYNTHESIS

Two reviewers extracted data onto an Excel spreadsheet. R version 4.4 was used for statistical analysis. Risk ratios (RR) and their 95% confidence intervals (CIs) were calculated and pooled using the random effects model. Cochrane's risk of bias (RoB 2) tool was used for quality assessment. This review has been registered with PROSPERO (CRD42024532740).

RESULTS

A total of 4 trials, comprising 413 participants, were included in this review. 206 patients received norepinephrine, while 207 received phenylephrine. The incidence of maternal bradycardia was significantly lower in the norepinephrine group compared with the phenylephrine group (RR = 0.25, 95 % CI = 0.16 to 0.39, p < 0.01). There were no statistical differences in other maternal outcomes or in the umbilical artery and umbilical vein blood gas analysis values. We also analyzed adverse events such as nausea (RR = 1.00, 95 % CI: 0.62 to 1.60, p = 1.00) and vomiting (RR = 0.99, 95 % CI: 0.89 to 1.11, p = 0.61), but they did not show a significant association with any group. All the trials had a moderate or low risk of bias.

CONCLUSION

Bolus doses of NE and PE for the treatment of post-spinal hypotension in preeclamptic women undergoing cesarean sections were found to exhibit comparable neonatal outcomes. However, NE provided superior maternal safety due to a lower incidence of bradycardia compared to PE.

Scoping Review: Is Push-Dose Norepinephrine a Better Choice?

Introduction

The use of push-dose vasopressors to treat anesthesia-induced hypotension is a common evidence-based practice among anesthesiologists. In more recent years, the use of push-dose vasopressors has transitioned to the emergency department (ED) and critical care setting. There is debate on the best choice of a push-dose vasopressor, with push-dose epinephrine or phenylephrine being more commonly used. This scoping review evaluated publications regarding the clinical use of push-dose norepinephrine.

Methods

We queried research studies in both PubMed and Google Scholar on the use of push-dose norepinephrine in human subjects, with numerous randomized controlled trials that compare norepinephrine to other vasopressors including phenylephrine, ephedrine, and epinephrine.

Results

A large majority of the studies were performed in the setting of spinal anesthesia prior to cesarean section, while several involved the administration of general anesthesia, with limited-to-no literature in the emergency and critical care setting. Of the 27 studies that we included in the review, 17 were randomized controlled trials. These studies demonstrated that norepinephrine was safe and effective.

Conclusion

Prior research has demonstrated the superiority of norepinephrine as a pressor of choice for various shock states. In this review, the safety and efficacy of push-dose norepinephrine is demonstrated, and favorable hemodynamic markers are shown in comparison to other agents. In addition, there are some safety and efficiency benefits to using push-dose norepinephrine from an administration standpoint, as well as clinically in decreased need for repeat doses. Further high-quality studies in the emergency and critical care realm would be beneficial to confirm these findings.

A Comparison of Norepinephrine versus Phenylephrine to Prevent Hypotension after Spinal Anesthesia for Cesarean Section: Systematic Review and Meta-Analysis

BACKGROUND

This systematic review and meta-analysis aimed to compare the effects of using phenylephrine or norepinephrine on the pH and base excess (BE) of the umbilical artery and vein in parturients undergoing cesarean section.

METHODS

The study protocol was registered in INPLASY. Independent researchers searched Ovid-Medline, Ovid-EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) databases and Google Scholar for relevant randomized controlled trials (RCTs). The primary outcome of this study was the umbilical artery (UA) or umbilical vein (UV) pH as neonatal condition at birth, and the secondary outcome was the UA or UV BE as an additional prognostic value over the measurement of umbilical pH.

RESULTS

There was no evidence of a difference between phenylephrine and norepinephrine for overall, UA, and UV pH (mean difference (MD) -0.001, 95% confidence interval (CI) -0.004 to 0.007; MD 0.000, 95%CI -0.004 to 0.004; and MD 0.002, 95%CI -0.013 to 0.017). There was also no evidence of a difference between phenylephrine and norepinephrine for overall, UA, and UV BE (MD 0.096, 95% CI -0.258 to 0.451; MD 0.076, 95%CI -0.141 to 0.294; and MD 0.121, 95%CI; -0.569 to 0.811). A meta-regression showed that factors such as umbilical artery or vein, infusion method, single or twin, and the number of parturients per study had no effect on the UA pH, UV pH, UA BE, or UV BE. No evidence of publication bias was detected.

CONCLUSIONS

There was no evidence of a difference between phenylephrine and norepinephrine for umbilical pH and BE. A subgroup analysis and meta-regression also did not show evidence of differences.

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.

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.

Efficacy of fixed-dose phenylephrine bolus for treating post-spinal hypotension: Comparison between pre-eclamptics and normotensives

Background and Aims

Pre-eclamptic parturients may have an exaggerated response to vasopressors. This study compares the efficacy of a 50 μg fixed bolus of phenylephrine for treatment of post-spinal hypotension in pre-eclamptic versus normotensive parturients.

Material and Methods

After written informed consent and ethics committee approval, 30 normotensive and 30 pre-eclamptic parturients between 18 and 40 years with singleton term pregnancy about to undergo cesarean section (CS) under spinal anesthesia were included. Post-spinal hypotension was treated with a 50 μg fixed bolus of phenylephrine. The cumulative dose of phenylephrine, the number of boluses, and the median dose required to treat the first hypotensive episode, total number of hypotensive episodes, maternal side effects, neonatal appearance, pulse, grimace, activity, and respiration (APGAR) scores, and umbilical arterial cord blood pH were noted. Statistical analysis was done using Student's t-test, Mann-Whitney U-test, Chi-square test/Fisher's exact test as appropriate. A P <0.05 was considered significant.

Results

The cumulative dose and number of boluses of phenylephrine required to treat post-spinal hypotension were comparable. The median dose required to treat the first episode of post-spinal hypotension was also similar (p = 0.792). The time to develop the first hypotensive episode was significantly earlier for group N (p = 0.002). The efficacy of a single fixed bolus of 50 μg phenylephrine was similar in both groups (p = 1.000). Neonatal median APGAR scores at 1 min after birth were significantly higher for group N (p = 0.016).

Conclusion

A fixed-dose bolus of 50 μg phenylephrine is safe and effective in treating post-spinal hypotension in pre-eclampsia. The efficacy of phenylephrine is comparable in pre-eclamptic and normotensive parturients.

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.

Chinese herbal medicine for the treatment of cardiovascular diseases ─ targeting cardiac ion channels

Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality, imposing an increasing global health burden. Cardiac ion channels (voltage-gated Na_V, Ca_V, K_Vs, and others) synergistically shape the cardiac action potential (AP) and control the heartbeat. Dysfunction of these channels, due to genetic mutations, transcriptional or post-translational modifications, may disturb the AP and lead to arrhythmia, a major risk for CVD patients. Although there are five classes of anti-arrhythmic drugs available, they can have varying levels of efficacies and side effects on patients, possibly due to the complex pathogenesis of arrhythmias. As an alternative treatment option, Chinese herbal remedies have shown promise in regulating cardiac ion channels and providing anti-arrhythmic effects. In this review, we first discuss the role of cardiac ion channels in maintaining normal heart function and the pathogenesis of CVD, then summarize the classification of Chinese herbal compounds, and elaborate detailed mechanisms of their efficacy in regulating cardiac ion channels and in alleviating arrhythmia and CVD. We also address current limitations and opportunities for developing new anti-CVD drugs based on Chinese herbal medicines.

Comparison of the Effect of Intravenous Bolus Norepinephrine and Ephedrine on Prevention of Post Spinal Hypotension in Cesarean Section: a Randomized Double-Blind Clinical Trial

Background:Currently, cesarean section is performed under spinal anesthesia. Hypotension is the most common complication of spinal anesthesia. This study aimed to compare the effect of intravenous bolus norepinephrine and ephedrine on prevention of post spinal hypotension in cesarean section. Methods:The present study was a double-blind clinical trial, in which 50 pregnant women aged 18-46 years, with ASA class I and II, were selected for cesarean section under spinal anesthesia and randomly assigned to two groups, one receiving norepinephrine (group A) and the other one ephedrine (group B). Immediately after spinal anesthesia, patients in group A received 5 μg of intravenous norepinephrine and those in group B 10 mg of intravenous ephedrine. The incidence of hypotension, bradycardia, mean systolic and diastolic blood pressure, and mean heart rate were recorded in a checklist. Patients with hypotension and bradycardia received 10 mg of ephedrine and 0.5 mg of atropine, respectively, and finally the amount of ephedrine and atropine was also recorded. Data were analyzed in SPSS, version 21 at a confidence level of 95%. Results:Hypotension had a frequency of 24% and 40% (P = 0.364) and the dose of ephedrine used to treat that condition was 15.0±8.37 and 18.18±7.51 mg (P = 0.434) in the norepinephrine and ephedrine groups, respectively. The mean heart rate was significantly lower in the norepinephrine group than the ephedrine one (P <0.001). Conclusion:Both norepinephrine and ephedrine were effective in preventing hypotension during cesarean section under spinal anesthesia, but tachycardia was less common with norepinephrine. Trial registration: The present study was registered on 17 May 2019 in the Iranian Clinical Trial Center (https://www.irct.ir) Identifier: IRCT20120915010841N17.

A Prospective Randomized Study Comparing the Bolus Doses of Norepinephrine and Phenylephrine for the Treatment of Spinal Induced Hypotension in Cesarean Section

Background: Spinal anesthetic-induced hypotension is the most worrisome complication for patients undergoing cesarean section under spinal anesthesia. The present study compares norepinephrine and phenylephrine bolus for the treatment of hypotension during spinal anesthesia for cesarean section.

Methods: One hundred twenty- six women aged between 22 and 40 years with singleton pregnancy classified to the American Society of Anesthesiologists (ASA) physical class I and II posted for elective cesarean section under spinal anesthesia were randomly divided into two groups of 63 each. Group I patients received phenylephrine 50 mcg (microgram) as an intravenous bolus, and Group II received 4 mcg of norepinephrine as an intravenous bolus to treat spinal hypotension.

Results: On comparing the demographic data of the patients in terms of age, weight, height, ASA Grade, level of block and surgery time no significant differences were found between the groups. Similarly, the fetal parameters were found to be not significantly different between the groups. However, the number of bolus doses of vasopressors required for the treatment of spinal-induced hypotension was significantly reduced in Group II (p=0.02). The frequency of bradycardia was found to be higher in patients who were given phenylephrine as compared to patients administered noradrenaline boluses (p=0.03). Five (7.93%) patients had shivering in Group I, while similar episodes were observed in 10 (15.87%) patients (p=0.05). Moreover, no significant difference was observed in comparing the heart rate and mean arterial pressure between the groups.

Conclusion: Intermittent boluses of norepinephrine are found to be effective in the management of spinal‑induced hypotension during caesarean section.

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.

A Review of Push-Dose Vasopressors in the Peri-operative and Critical Care Setting

During hospitalization, the risk of hypotension and associated sequelae remain important considerations for patient outcomes. The use of push-dose vasopressors (PDP) outside of the operating room has increased in recent years to combat the negative effects of hypotension. This narrative review evaluates the utility of PDP in its traditional perioperative setting as well as in areas of increasing use such as the emergency department and intensive care unit. Articles evaluating PDP highlight successful increases in blood pressure with all agents but differ in rates of adverse events and most lack direct comparison of PDP agents in regard to safety and efficacy. Agents utilized as PDP, including epinephrine, phenylephrine, norepinephrine, vasopressin, and ephedrine vary in mechanism of action, onset of action, and duration of action. These variations in pharmacology along with published literature may lead to differences in the preferred PDP for various clinical scenarios. Many adverse events associated with PDP have been due to dosing errors highlighting the importance of education surrounding the use of these agents. Additional research is necessary to further elucidate the risks and benefits of PDP in clinical practice, and to determine which PDP is truly preferred. Careful consideration should be given when determining the appropriateness of this administration method of vasopressors in various clinical scenarios.

An advanced double intravenous vasopressor automated system to treat hypotension during spinal anaesthesia for caesarean section: A pilot study

BACKGROUND

During spinal anaesthesia for caesarean section, haemodynamic instability may lead to maternal and foetal complications. We developed a novel advanced double intravenous vasopressor automated system (ADIVA) by using a continuous blood pressure and heart rate monitor. Treatment of hypotension was based on three criteria: the drug (phenylephrine or ephedrine) according to the heart rate; the dose of vasopressor determined by the degree of hypotension; a fast or slow bolus of vasopressor administered depending on whether there was a negative or positive gradient of SBP changes, respectively.

OBJECTIVE

The aim of this pilot study was to investigate the feasibility of the ADIVA algorithm.

DESIGN

A prospective pilot study.

SETTING

Single obstetrics and gynaecology centre in Singapore.

PATIENTS

Women undergoing elective caesarean delivery under spinal anaesthesia.

INTERVENTION

Automated administration of ephedrine or phenylephrine based on changes in blood pressure and heart rate (via the ADIVA algorithm) detected on continuous noninvasive haemodynamic monitoring using noninvasive continuous haemodynamic monitor (Nexfin).

MAIN OUTCOME MEASURES

The primary outcome was the incidence of hypotension, defined as SBP less than 80% of baseline. The secondary outcome measures were reactive hypertension, total vasopressor requirement, maternal and neonatal outcomes and system performance.

RESULTS

Forty-five women were recruited. Thirty-one women (69.9%) had at least one reading of hypotension. SBP was within ±20% of the baseline in a mean ± SD of 79.7 ± 17.6% of measurements. Forty-four (97.8%) women required phenylephrine before delivery, while 15 (33.3%) required ephedrine. No rescue medications were required. Three women (6.7%) had nausea and two (4.4%) vomiting. All neonates had APGAR scores of 9 at 5 min.

CONCLUSION

The ADIVA system, with noninvasive continuous haemodynamic monitoring, was able to maintain maternal SBP within ±20% of baseline for the vast majority of the measurements. This system had good maternal and foetal outcomes with minimal intervention from the attending anaesthetist.

TRIAL REGISTRATION

NCT03620942.

Comparison of phenylephrine and norepinephrine for treatment of spinal hypotension during elective cesarean delivery- A randomised, double-blind study

Background and Aims

Hypotension following subarachnoid block for cesarean delivery (CD) is common. We compared the effect of bolus administration of norepinephrine and phenylephrine on umbilical artery pH (primary objective) and their efficacy for the treatment of maternal hypotension (secondary objective) in term parturients undergoing elective CD under spinal anesthesia.

Material and Methods

In a randomized, double-blinded study, parturients received 1 mL boluses of either phenylephrine 100 μg/mL (group phenylephrine; n = 45) or norepinephrine 7.5 μg/mL (group norepinephrine; n = 45) whenever maternal systolic blood pressure decreased to ≤80% of baseline. Maternal hemodynamic changes, vasopressor, and atropine requirement and neonatal outcome (umbilical cord blood gas analysis, Apgar scores, neonatal neurobehavioral response) were assessed.

Results

The Apgar scores and umbilical cord blood gas analysis were comparable between groups. The neurobehavioral scale score was significantly higher in group NE compared with that in group PE at 24 h and 48 h; P = 0.007 and 0.002, respectively. The number of vasopressor doses and time to the first vasopressor requirement for maintaining systolic pressure >80% of baseline was comparable in both groups. Incidence of bradycardia (P = 0.009), reactive hypertension (P = 0.003), and dose requirement of atropine (P = 0.005) was higher in group PE compared with group NE.

Conclusions

In term normotensive parturients who received bolus norepinephrine 7.5 μg or phenylephrine 100 μg for the treatment of post-spinal hypotension during CD, neonatal umbilical cord blood gas analysis and Apgar scores were comparable. Norepinephrine use was associated with a lower incidence of maternal bradycardia and reactive hypertension compared with phenylephrine.

Comparison of push-dose phenylephrine and epinephrine in the emergency department

BACKGROUND

There is limited evidence to support the efficacy and safety of push-dose vasopressor (PDP) use outside of the operating room (OR). Specifically, there are few head-to-head comparisons of different PDP in these settings. The purpose of this study was to compare the efficacy and safety of push-dose phenylephrine (PDP-PE) and epinephrine (PDP-E) in the Emergency Department (ED).

METHODS

This retrospective, single-center study evaluated adults given PDP-PE or PDP-E in the ED from May 2017 to November 2020. The primary outcome was a change in heart rate (HR). Secondary outcomes included changes in blood pressure, adverse effects, dosing errors, fluid and vasopressor requirements, ICU and hospital lengths of stay (LOS), and in-hospital mortality.

RESULTS

Ninety-six patients were included in the PDP-PE group and 39 patients in the PDP-E group. Median changes in HR were 0 [-7, 6] and - 2 [-15, 5] beats per minute (BPM) for PDP-PE and PDP-E, respectively (p = 0.138). PDP-E patients had a greater median increase in systolic blood pressure (SBP) (33 [24, 53] vs. 26 [8, 51] mmHg; p = 0.049). Dosing errors occurred more frequently in patients that received PDP-E (5/39 [12.8%] vs. 2/96 [2.1%]; p = 0.021). PDP-E patients more frequently received continuous epinephrine infusions before and after receiving PDP-E. There were no differences in adverse effects, fluid requirements, LOS, or mortality.

CONCLUSION

PDP-E provided a greater increase in SBP compared to PDP-PE. However, dosing errors occurred more frequently in those receiving PDP-E. Larger head-to-head studies are necessary to further evaluate the efficacy and safety of PDP-E and PDP-PE.

Preeclampsia in 2021-a Perioperative Medical Challenge for the Anesthesiologist

The authors provide a review of recent advances in the understanding of pathophysiology and perioperative management of preeclampsia and eclampsia, from the perspective of the anesthesiologist. This review includes aspects of assessment of severity of disease, hemodynamic monitoring, peripartum anesthesia care, and postpartum management. The perioperative management of patients with eclampsia is also discussed.

In-silico analysis of closed-loop vasopressor control of phenylephrine versus norepinephrine

We have previously demonstrated in in-silico, pre-clinical animal models, and finally human clinical studies the ability of a novel closed-loop vasopressor titration system to manage norepinephrine infusion rates to keep mean arterial blood pressure in a very tight range, reduce hypotension time and severity, and reduce overtreatment. We hypothesized that the same controller could, with modification for pharmacologic differences, suitably titrate a lower-potency longer duration of action agent like phenylephrine. Using the same physiologic simulation model as was used previously for in-silico testing of our controller for norepinephrine, we first updated the model to include a new vasopressor agent modeled after phenylephrine. A series of simulation tests patterned after our previous norepinephrine study was then conducted, this time using phenylephrine for management, in order to both test the system with the new agent and allow for comparisons between the two. Hundreds of simulation trials were conducted across a range of patient and environmental variances. The controller performance was characterized based on time in target, time above and below target, coefficient of variation, and using Varvel's criteria. The controller kept the simulated patients' MAP in target for 94% of management time in the simple scenarios and more than 85% of time in the most challenging scenarios. Varvel criteria were all under 1% error for expected pharmacologic responses and were consistent with those established for norepinephrine in our previous studies. The controller was able to acceptably titrate phenylephrine in this simulated patient model consistent with performance previously seen for norepinephrine after adjusting for the anticipated differences between the two agents.

A randomised double-blind comparison of phenylephrine and norepinephrine for the management of postspinal hypotension in pre-eclamptic patients undergoing caesarean section

BACKGROUND

Studies comparing phenylephrine and norepinephrine for the treatment of postspinal hypotension in pre-eclamptic patients are limited.

OBJECTIVE

To compare bolus doses of phenylephrine and norepinephrine for treating hypotension in pre-eclamptic mothers undergoing caesarean section under spinal anaesthesia. It was hypothesised that norepinephrine and phenylephrine use would be associated with similar neonatal outcome.

DESIGN

Randomised controlled study.

SETTING

Single centre, tertiary care, university teaching hospital, from December 2018 to March 2020.

PATIENTS

A total of 86 women with pre-eclampsia and a singleton pregnancy who developed postspinal hypotension during caesarean section.

INTERVENTIONS

Patients received intravenous phenylephrine (50 μg) or norepinephrine (4 μg) for treatment of hypotension, defined as a fall in baseline systolic BP by ≥ 20% or an absolute value < 100 mmHg.

MAIN OUTCOME MEASURES

The primary outcome was umbilical artery pH. Secondary outcomes included Apgar scores, the number of hypotensive episodes, vasopressor requirements, the incidence of tachycardia/bradycardia/arrhythmias/hypertension and maternal complications.

RESULTS

Umbilical artery pH was not different between the phenylephrine and norepinephrine groups (7.26 ± 0.06 and 7.27 ± 0.06, respectively; P = 0.903). The median [IQR] number of hypotensive episodes was higher in the norepinephrine than the phenylephrine group: 2 [1 to 3] vs 1 [1 to 2], respectively; P = 0.014. Apgar scores, total number of vasopressor boluses required, systolic BP trends and the incidence of maternal complications were comparable in the two groups. Heart rate (HR) values were lower in phenylephrine group (P = 0.026), and one patient in phenylephrine group and none in the norepinephrine group developed bradycardia (HR < 50 bpm), P = 1.000.

CONCLUSIONS

In women with pre-eclampsia undergoing caesarean section, bolus doses of phenylephrine (50 μg) and norepinephrine (4 μg) used to treat hypotension after spinal anaesthesia are equally effective with similar neonatal and maternal outcomes.

TRIAL REGISTRATION

CTRI/2018/11/016478.

Comparison of two vasopressor protocols for preventing hypotension post-spinal anesthesia during cesarean section: a randomized controlled trial

Background:

Norepinephrine infusion decreases hypotension after spinal anesthesia during cesarean section. This study aimed to compare the efficacy of norepinephrine infusion and ephedrine bolus against post-spinal hypotension in parturients.

Methods:

In this double-blinded, randomized controlled clinical trial, parturients scheduled for elective cesarean section were randomly allocated to receive norepinephrine infusion (0.05 μg·kg⁻¹·min⁻¹) just before spinal anesthesia continuing for 30 min or ephedrine bolus (0.15 mg/kg) just before spinal anesthesia. A rescue bolus (5 μg norepinephrine for the norepinephrine group, and 5 mg ephedrine for the ephedrine group) was administered whenever hypotension occurred. Our primary outcome was the incidence of hypotension within 30 min of spinal anesthesia administration. Secondary outcomes included maternal and neonatal outcomes 30 min after spinal block, and neonatal cerebral oxygenation 10 min after birth.

Results:

In total, 190 patients were enrolled; of these patients, 177 were included in the final analysis. Fewer patients suffered hypotension in the norepinephrine group than in the ephedrine group (29.5% vs. 44.9%, odds ratio [OR]: 0.51, 95% confidence interval [CI]: 0.28–0.95, P = 0.034). Moreover, the tachycardia frequency was lower in the norepinephrine group than in the ephedrine group (OR: 0.22, 95% CI: 0.11–0.44, P < 0.001), and patients suffered less nausea and vomiting (OR: 0.28, 95% CI: 0.11–0.70, P = 0.004). There was no difference in Apgar scores and umbilical arterial blood gas analysis between the two groups. However, neonatal cerebral regional saturations were significantly higher after birth in the norepinephrine group than in the ephedrine group (mean difference: 2.0%, 95% CI: 0.55%–3.45%, P = 0.008).

Conclusion:

In patients undergoing elective cesarean section with spinal anesthesia, norepinephrine infusion compared to ephedrine bolus resulted in less hypotension and tachycardia, and exhibited potential neonatal benefits.

Trial Registration:

ClinicalTrials.gov, NCT02542748; https://clinicaltrials.gov/ct2/show/record/NCT02542748

A Multi-Objective Approach for Drug Repurposing in Preeclampsia

Preeclampsia is a hypertensive disorder that occurs during pregnancy. It is a complex disease with unknown pathogenesis and the leading cause of fetal and maternal mortality during pregnancy. Using all drugs currently under clinical trial for preeclampsia, we extracted all their possible targets from the DrugBank and ChEMBL databases and labeled them as "targets". The proteins labeled as "off-targets" were extracted in the same way but while taking all antihypertensive drugs which are inhibitors of ACE and/or angiotensin receptor antagonist as query molecules. Classification models were obtained for each of the 55 total proteins (45 targets and 10 off-targets) using the TPOT pipeline optimization tool. The average accuracy of the models in predicting the external dataset for targets and off-targets was 0.830 and 0.850, respectively. The combinations of models maximizing their virtual screening performance were explored by combining the desirability function and genetic algorithms. The virtual screening performance metrics for the best model were: the Boltzmann-Enhanced Discrimination of ROC (BEDROC)α=160.9 = 0.258, the Enrichment Factor (EF)1% = 31.55 and the Area Under the Accumulation Curve (AUAC) = 0.831. The most relevant targets for preeclampsia were: AR, VDR, SLC6A2, NOS3 and CHRM4, while ABCG2, ERBB2, CES1 and REN led to the most relevant off-targets. A virtual screening of the DrugBank database identified estradiol, estriol, vitamins E and D, lynestrenol, mifrepristone, simvastatin, ambroxol, and some antibiotics and antiparasitics as drugs with potential application in the treatment of preeclampsia.

Vasopressor dose equivalence: A scoping review and suggested formula

PURPOSE

Calculating equipotent doses between vasopressor agents is necessary in clinical practice and research pertaining to the management of shock. This scoping review summarizes conversion ratios between vasopressors and provides a formula to incorporate into study designs.

MATERIALS AND METHODS

Medline, Embase and Web of Science databases were searched from inception to 21st October 2020. Additional papers were obtained through bibliography searches of retrieved articles. Two investigators assessed articles for eligibility. Clinical trials comparing the potency of at least two intravenous vasopressors (norepinephrine, epinephrine, dopamine, phenylephrine, vasopressin, metaraminol or angiotensin II), with regard to an outcome of blood pressure, were selected.

RESULTS

Of 16,315 articles, 21 were included for synthesis. The range of conversion ratios equivalent to one unit of norepinephrine were: epinephrine (0.7-1.4), dopamine (75.2-144.4), metaraminol (8.3), phenylephrine (1.1-16.3), vasopressin (0.3-0.4) and angiotensin II (0.07-0.13). The following formula may be considered for the calculation of norepinephrine equivalents (NE) (all in mcg/kg/min, except vasopressin in units/min): NE = norepinephrine + epinephrine + phenylephrine/10 + dopamine/100 + metaraminol/8 + vasopressin*2.5 + angiotensin II*10.

CONCLUSION

A summary of equipotent ratios for common vasopressors used in clinical practice has been provided. Our formula may be considered to calculate NE for studies in the intensive care unit.

Prehospital Efficacy and Adverse Events Associated with Bolus Dose Epinephrine in Hypotensive Patients During Ground-Based EMS Transport

BACKGROUND

The utility and efficacy of bolus dose vasopressors in hemodynamically unstable patients is well-established in the fields of general anesthesia and obstetrics. However, in the prehospital setting, minimal evidence for bolus dose vasopressor use exists and is primarily limited to critical care transport use. Hypotensive episodes, whether traumatic, peri-intubation-related, or septic, increase patient mortality. The purpose of this study is to assess the efficacy and adverse events associated with prehospital bolus dose epinephrine use in non-cardiac arrest, hypotensive patients treated by a single, high-volume, ground-based Emergency Medical Services (EMS) agency.

METHODS

This is a retrospective, observational study of all non-cardiac arrest EMS patients treated for hypotension using bolus dose epinephrine from September 12, 2018 through September 12, 2019. Inclusion criteria for treatment with bolus dose epinephrine required a systolic blood pressure (SBP) measurement <90mmHg. A dose of 20mcg every two minutes, as needed, was allowed per protocol. The primary data source was the EMS electronic medical record.

RESULTS

Forty-two patients were treated under the protocol with a median (IQR) initial SBP immediately prior to treatment of 78mmHg (65-86) and a median (IQR) initial mean arterial pressure (MAP) of 58mmHg (50-66). The post-bolus SBP and MAP increased to 93mmHg (75-111) and 69mmHg (59-83), respectively. The two most common patient presentations requiring protocol use were altered mental status (55%) and respiratory failure (31%). Over one-half of the patients treated required both advanced airway management (62%) and multiple bolus doses of vasopressor support (55%). A single episode of transient severe hypertension (SBP>180mmHg) occurred, but there were no episodes of unstable tachyarrhythmia or cardiac arrest while en route or upon arrival to the receiving hospitals.

CONCLUSION

These preliminary data suggest that the administration of bolus dose epinephrine may be effective at rapidly augmenting hypotension in the prehospital setting with a minimal incidence of adverse events. Paramedic use of bolus dose epinephrine successfully increased SBP and MAP without clinically significant side effects. Prospective studies with larger sample sizes are needed to further investigate the effects of prehospital bolus dose epinephrine on patient morbidity and mortality.

Adaptive optimal target controlled infusion algorithm to prevent hypotension associated with labor epidural: An adaptive dynamic programming approach

Patients receiving labor epidurals commonly experience arterial hypotension as a complication of neuraxial block. The purpose of this study was to design an adaptive optimal controller for an infusion system to regulate mean arterial pressure. A state-space model relating mean arterial pressure to Norepinephrine (NE) infusion rate was derived for controller design. A data-driven adaptive optimal control algorithm was developed based on adaptive dynamic programming (ADP). The stability and disturbance rejection ability of the closed-loop system were tested via a simulation model calibrated using available clinical data. Simulation results indicated that the settling time was six minutes and the system showed effective disturbance rejection. The results also demonstrate that the adaptive optimal control algorithm would achieve individualized control of mean arterial pressure in pregnant patients with no prior knowledge of patient parameters.

A Review on Worldwide Ephedra History and Story: From Fossils to Natural Products Mass Spectroscopy Characterization and Biopharmacotherapy Potential

Growing worldwide, the genus Ephedra (family Ephedraceae) had a medicinal, ecological, and economic value. The extraordinary morphological diversity suggests that Ephedra was survivor of an ancient group, and its antiquity is also supported by fossil data. It has recently been suggested that Ephedra appeared 8–32 million years ago, and a few megafossils document its presence in the Early Cretaceous. Recently, the high analytical power provided by the new mass spectrometry (MS) instruments is making the characterization of Ephedra metabolites more feasible, such as ephedrine series. In this regard, the chemical compounds isolated from crude extracts, fractions, and few isolated compounds of Ephedra species were characterized by MS-based techniques (LC-MS, LC-ESI-MS, HPLC-PDA-ESI/MS, LC-DAD-ESI/MSn, LC/Orbitrap MS, etc.). Moreover, we carry out an exhaustive review of the scientific literature on biomedicine and pharmacotherapy (anticancer, antiproliferative, anti-inflammatory, antidiabetic, antihyperlipidemic, antiarthritic, and anti-influenza activities; proapoptotic and cytotoxic potential; and so on). Equally, antimicrobial and antioxidant activities were discussed. This review is focused on all these topics, along with current studies published in the last 5 years (2015–2019) providing in-depth information for readers.

A systematic review of phenylephrine vs. noradrenaline for the management of hypotension associated with neuraxial anaesthesia in women undergoing caesarean section

Phenylephrine is recommended for the management of hypotension after spinal anaesthesia in women undergoing caesarean section. Noradrenaline, an adrenergic agonist with weak β-adrenergic activity, has been reported to have a more favourable haemodynamic profile than phenylephrine. However, there are concerns that noradrenaline may be associated with a higher risk of fetal acidosis, defined as an umbilical artery pH < 7.20. We performed a systematic review of trials comparing noradrenaline with phenylephrine, concentrating on primary outcomes of fetal acidosis and maternal hypotension. We identified 13 randomised controlled trials including 2002 patients. Heterogeneity among the studies was high, and there were too few data to calculate a pooled effect estimate. Fetal acidosis was assessed in four studies that had a low risk of bias and a low risk of confounding, that is, studies which used a prophylactic vasopressor and where women received the allocated vasopressor only. There were no significant differences between these studies. No significant differences were observed for hypotension. Two trials found a significantly lower incidence of bradycardia when using noradrenaline. Cardiac output was significantly higher after noradrenaline in two of three studies. For other secondary outcomes including nausea, vomiting and Apgar scores at 1 and 5 min, no studies found significant differences. The evidence so far is too limited to support an advantage of noradrenaline over phenylephrine. Concerns of a deleterious effect of noradrenaline on fetal blood gas status cannot currently be assuaged by the available data from randomised controlled studies.

Comparison of norepinephrine and phenylephrine boluses for the treatment of hypotension during spinal anaesthesia for caesarean section - A randomised controlled trial

Background and Aims:

Hypotension following spinal anaesthesia for caesarean section is common in spite of adequate fluid loading. Phenylephrine is the recommended drug to treat spinal hypotension during caesarean section. Recently, norepinephrine boluses are being suggested as an alternative to phenylephrine boluses. The aim of our study was to compare the effectiveness of bolus doses of norepinephrine with phenylephrine to treat spinal hypotension during caesarean section.

Methods:

Fifty patients undergoing elective caesarean section under spinal anaesthesia were randomly assigned into two groups. Group P patients received phenylephrine 50 μg as an intravenous bolus and group N received 4 μg of norepinephrine as intravenous bolus to treat spinal hypotension. The primary objective of our study was to compare the number of bolus doses of norepinephrine or phenylephrine required to treat spinal hypotension. The secondary objectives were to compare the incidence of bradycardia, hypertension, nausea and vomiting in mother and foetal outcomes.

Results:

The number of boluses of vasopressors required to treat hypotension was significantly lower in group N (1.40 ± 0.577 vs. 2.28 ± 1.061, P = 0.001). The frequency of bradycardia was high in group P, but this difference was not statistically significant (4%vs. 20%, P = 0.192). Maternal complications such as nausea and vomiting and shivering were comparable between the groups. The foetal parameters were also comparable between the two groups.

Conclusion:

Intermittent boluses of norepinephrine are effective in the management of spinal-induced hypotension during caesarean section. The neonatal outcomes were similar in both the groups. Norepinephrine boluses can be considered as an alternative to phenylephrine boluses.