Maternal and neonatal effects of bolus administration of ephedrine and phenylephrine during spinal anaesthesia for caesarean delivery: a randomised study

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.

Postspinal Anesthesia Hypotension in Caesarean Delivery: A Narrative Review

Anesthesiologists frequently deal with spinal hypotension when administering spinal anesthesia (SA) for a Caesarean section (C-section). The physiological changes that occur during pregnancy necessitate modifications to anesthesia and analgesia procedures to provide safe and efficient care for the expectant patient. It is believed that giving the patient SA during a C-section will increase their degree of comfort and pain management both during and after the surgical process. It is less expensive, easier to give, and delivers a consistent anesthetic onset, early ambulation, and the start of breastfeeding. As C-section is a very common operation performed in every healthcare unit, dealing with postspinal hypotension is a daily situation faced by anesthetists with variable levels of experience. However, understanding and addressing hypotension induced by SA is crucial as it affects the mother and the fetus negatively. This review aims to contribute to enhancing patient care and safety in the context of C-sections by identifying hypotension timely and managing it effectively. It is advised to healthcare workers to leverage the insights from the review to improve patient outcomes in routine practice.

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.

A Randomized Controlled Trial Comparing the Effect of Phenylephrine by Intramuscular Route With Intravenous Infusion in Maintaining Haemodynamic Stability During Elective Lower Segment Caesarean Section Under Spinal Anaesthesia

Background Hypotension is a commonly encountered side effect in patients undergoing spinal anaesthesia, particularly in patients undergoing caesarean section. Phenylephrine is a widely used drug to treat spinal-induced hypotension and to maintain hemodynamic stability. Our aim is to evaluate the effectiveness of phenylephrine given through two different routes prophylactically in prevention of post-spinal hypotension in patients undergoing caesarean section. Methods A total of 150 healthy pregnant women undergoing elective caesarean section were randomly allocated into three groups: Group M (prophylactic intramuscular use of 2 mg phenylephrine), group V (prophylactic intravenous infusion of 30 mcg phenylephrine per minute), and group P (no prophylaxis), rescue phenylephrine 30 mcg IV and atropine 0.6 mg IV were used intraoperatively to treat bradycardia and hypotension in all three groups. The primary outcome was maternal hemodynamic changes. Results There was an insignificant difference in demographic data between the groups. Maternal systolic and diastolic blood pressure were more stable in group M compared to group V and group P. Heart rate was significantly lower only in group V. We did not observe any statistical difference between the groups in the APGAR score or the fetal arterial blood gas values. The incidence of nausea and vomiting was more in group P. Conclusion Preventive intramuscular phenylephrine exhibited a more stable maternal hemodynamics when compared with the prophylactic intravenous infusion of phenylephrine and placebo in elective caesarean under spinal anaesthesia.

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.

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.

Analysis of Risk Factors for Intraoperative Hypotension in Cesarean Section and Poor Prognosis of Neonates

Objective

To analyze the risk factors of intraoperative hypotension in cesarean section women and poor prognosis of neonates.

Methods

The clinical data of 1071 cesarean section women admitted to The Affiliated Jiangning Hospital of Nanjing Medical University from January 2021 to December 2021 were retrospectively analyzed. They were divided into hypotension group (n = 472) and normal control group (n = 599) according to whether there was hypotension during operation. The correlations between the clinical data of cesarean section and the occurrence of intraoperative hypotension and poor prognosis of neonates were analyzed by logistic regression analysis. Receiver operating curve (ROC) was drawn and the area under the curve (AUC) was calculated.

Results

Logistic regression analysis results showed that BMI ≥30 kg/m2, infant weight ≥3500 g, spinal anesthesia, puncture site L2-3, bupivacaine dose>10 mg, ropivacaine dose>50 mg, and perfusion index≥4 were the risk factor for intraoperative hypotension in cesarean section (p < 0.01) and BMI ≥30 kg/m2, umbilical cord around neck, spinal anesthesia, and perfusion index≥4 were risk factors for poor prognosis of neonates (p < 0.01). The AUC of ROC for BMI to diagnose intraoperative hypotension in cesarean section women was 0.6240 (95% CI: 0.59-0.66, p < 0.01), the sensitivity was only 30.20% (95% CI: 26.73%-35.02%), and the specificity was 87.65% (84.77%-90.04%), and the AUC of BMI for the diagnosis of poor prognosis of neonates was 0.5647 (95% CI: 0.5013-0.6280, p = 0.049), and the sensitivity was 51.19% (95% CI: 40.69%-61.59%), and the specificity was 64.34% (61.30%-67.26%). The AUC of perfusion index for the diagnosis of intraoperative hypotension in cesarean section women was 0.8333 (95% CI: 0.8081-0.8584, p < 0.01), the sensitivity was 94.49% (95% CI: 92.05%-96.21%), and the specificity was 73.12% (69.43%-76.52%); the AUC of perfusion index for the diagnosis of ROC with poor prognosis of neonates was 0.6164 (95% CI: 0.5538-0.6791, p < 0.01), the sensitivity was 70.24% (95% CI: 59.75%-78.96%), and the specificity was 50.86% (47.75%-53.97%).

Conclusion

The prediction model established by BMI, infant weight, anesthesia method, puncture site, anesthetic drug dose, and perfusion index has guiding value for clinical prediction of cesarean section maternal hypotension. The prediction model established by BMI, umbilical cord around neck, anesthesia method, and perfusion index has guiding value for clinical prediction of poor prognosis of neonates.

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.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

BACKGROUND

Maternal hypotension is the most frequent complication of spinal anaesthesia for caesarean section. It can be associated with nausea or vomiting and may pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis, neurological injury).

OBJECTIVES

To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (9 August 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials, including full texts and abstracts, comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section. We excluded studies if hypotension was not an outcome measure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study quality and extracted data from eligible studies. We report 'Summary of findings' tables using GRADE.

MAIN RESULTS

We included 125 studies involving 9469 women. Interventions were to prevent maternal hypotension following spinal anaesthesia only, and we excluded any interventions considered active treatment. All the included studies reported the review's primary outcome. Across 49 comparisons, we identified three intervention groups: intravenous fluids, pharmacological interventions, and physical interventions. Authors reported no serious adverse effects with any of the interventions investigated. Most trials reported hypotension requiring intervention and Apgar score of less than 8 at five minutes as the only outcomes. None of the trials included in the comparisons we describe reported admission to neonatal intensive care unit. Crystalloid versus control (no fluids) Fewer women experienced hypotension in the crystalloid group compared with no fluids (average risk ratio (RR) 0.84, 95% confidence interval (CI) 0.72 to 0.98; 370 women; 5 studies; low-quality evidence). There was no clear difference between groups in numbers of women with nausea and vomiting (average RR 0.19, 95% CI 0.01 to 3.91; 1 study; 69 women; very low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (60 babies, low-quality evidence). Colloid versus crystalloid Fewer women experienced hypotension in the colloid group compared with the crystalloid group (average RR 0.69, 95% CI 0.58 to 0.81; 2009 women; 27 studies; very low-quality evidence). There were no clear differences between groups for maternal hypertension requiring intervention (average RR 0.64, 95% CI 0.09 to 4.46, 3 studies, 327 women; very low-quality evidence), maternal bradycardia requiring intervention (average RR 0.98, 95% CI 0.54 to 1.78, 5 studies, 413 women; very low-quality evidence), nausea and/or vomiting (average RR 0.89, 95% CI 0.66 to 1.19, 14 studies, 1058 women, I² = 29%; very low-quality evidence), neonatal acidosis (average RR 0.83, 95% CI 0.15 to 4.52, 6 studies, 678 babies; very low-quality evidence), or Apgar score of less than 8 at five minutes (average RR 0.24, 95% CI 0.03 to 2.05, 10 studies, 730 babies; very low-quality evidence). Ephedrine versus phenylephrine There were no clear differences between ephedrine and phenylephrine groups for preventing maternal hypotension (average RR 0.92, 95% CI 0.71 to 1.18; 401 women; 8 studies; very low-quality evidence) or hypertension (average RR 1.72, 95% CI 0.71 to 4.16, 2 studies, 118 women, low-quality evidence). Rates of bradycardia were lower in the ephedrine group (average RR 0.37, 95% CI 0.21 to 0.64, 5 studies, 304 women, low-quality evidence). There was no clear difference in the number of women with nausea and/or vomiting (average RR 0.76, 95% CI 0.39 to 1.49, 4 studies, 204 women, I² = 37%, very low-quality evidence), or babies with neonatal acidosis (average RR 0.89, 95% CI 0.07 to 12.00, 3 studies, 175 babies, low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (321 babies; low-quality evidence). Ondansetron versus control Ondansetron administration was more effective than control (placebo saline) for preventing hypotension requiring treatment (average RR 0.67, 95% CI 0.54 to 0.83; 740 women, 8 studies, low-quality evidence), bradycardia requiring treatment (average RR 0.49, 95% CI 0.28 to 0.87; 740 women, 8 studies, low-quality evidence), and nausea and/or vomiting (average RR 0.35, 95% CI 0.24 to 0.51; 653 women, 7 studies, low-quality evidence). There was no clear difference between the groups in rates of neonatal acidosis (average RR 0.48, 95% CI 0.05 to 5.09; 134 babies; 2 studies, low-quality evidence) or Apgar scores of less than 8 at five minutes (284 babies, low-quality evidence). Lower limb compression versus control Lower limb compression was more effective than control for preventing hypotension (average RR 0.61, 95% CI 0.47 to 0.78, 11 studies, 705 women, I² = 65%, very low-quality evidence). There was no clear difference between the groups in rates of bradycardia (RR 0.63, 95% CI 0.11 to 3.56, 1 study, 74 women, very low-quality evidence) or nausea and/or vomiting (average RR 0.42, 95% CI 0.14 to 1.27, 4 studies, 276 women, I² = 32%, very-low quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (130 babies, very low-quality evidence). Walking versus lying There was no clear difference between the groups for women with hypotension requiring treatment (RR 0.71, 95% CI 0.41 to 1.21, 1 study, 37 women, very low-quality evidence). Many included studies reported little to no information that would allow an assessment of their risk of bias, limiting our ability to draw meaningful conclusions. GRADE assessments of the quality of evidence ranged from very low to low. We downgraded evidence for limitations in study design, imprecision, and indirectness; most studies assessed only women scheduled for elective caesarean sections. External validity also needs consideration. Readers should question the use of colloids in this context given the serious potential side effects such as allergy and renal failure associated with their administration.

AUTHORS' CONCLUSIONS

While interventions such as crystalloids, colloids, ephedrine, phenylephrine, ondansetron, or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension in some women. We cannot draw any conclusions regarding rare adverse effects associated with use of the interventions (for example colloids) due to the relatively small numbers of women studied.

The Effect of Phenylephrine Infusion on Maternal Hemodynamic Changes During Spinal Anesthesia for Cesarean Delivery

Background

Spinal anesthesia is used as a common anesthetic technique in many routine and outpatient surgeries.

Objectives

The aim of this study was to determine the effect of phenylephrine on maternal hemodynamic changes during spinal anesthesia for cesarean delivery.

Methods

This double-blind randomized controlled trial was conducted on 116 pregnant women candidate for the elective cesarean section through spinal anesthesia in the Shahid Akbarabadi Hospital, Tehran in 2019. The eligible women were randomly divided into the intervention (phenylephrine; n = 58) and control (normal saline; n = 58) groups. The data collection tool was a checklist, including the demographic and clinical variables, such as age, height, weight, body mass index, gravid, gestational age, Apgar score of 1 and 5, systolic blood pressure, diastolic blood pressure, heart rate, mean arterial pressure, SPO2, PH of the umbilical cord, PCO2, HCO3, base excess, nausea, and vomiting. Data were analyzed using SPSS 24 software and P value < 0.05 was considered as significant.

Results

The intervention and control groups showed a significant difference in terms of the PH of the umbilical cord, PCO2, and nausea and vomiting (P value < 0.05). The results of the repeated measure ANOVA test showed a significant statistical difference between the intervention and control groups at different time points in terms of arterial pressure, systolic and diastolic blood pressures (P value < 0.05).

Conclusions

Phenylephrine is effective in the prevention of some complications, like reducing mean arterial pressure, systolic and diastolic blood pressures, nausea, and vomiting during spinal anesthesia for cesarean delivery. Therefore, these drugs can be used based on maternal hemodynamic status during spinal anesthesia for cesarean delivery.

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.

Preventive intramuscular phenylephrine in elective cesarean section under spinal anesthesia: A randomized controlled trial

BACKGROUND

Phenylephrine is the first-line vasoactive drug in the cesarean section under spinal anesthesia. The rate of hypotension remains high after intravenous preventive use of phenylephrine. However, few studies have investigated the effect of preventive intramuscular phenylephrine via a longer period of usage on fetal and maternal outcomes.

METHODS

A total of 99 healthy parturients undergoing elective cesarean delivery were randomly allocated into three groups: M group (preventive intramuscular use of 5 mg phenylephrine), V group (preventive intravenous use of 100 μg phenylephrine), and P group (0.9% normal saline placebo). Rescue phenylephrine, ephedrine and atropine were used intraoperatively to adjust blood pressure and heart rate. The primary outcome was umbilical artery pH.

RESULTS

Significant differences in umbilical artery pH (M group: 7.32 ± 0.05 versus V group: 7.25 ± 0.04 versus P group: 7.21 ± 0.03, P < 0.05), fetal acidosis (M group: 3% [n = 33] versus V group: 15% [n = 33] versus P group: 30% [n = 33], P = 0.01) and maternal intraoperative hypotension (M group: 12% [33] versus V group: 39% [33] versus P group: 73% [33], P < 0.0001) were identified among the groups. Multiple linear regression analysis demonstrated that treating arms, neonatal birthweight and the interval from the end of anesthesia to baby delivery were associated with umbilical artery pH.

CONCLUSION

Compared with the preventive intravenous use of phenylephrine and placebo, preventive intramuscular phenylephrine exhibited a better neonatal acid-base status and more stable maternal hemodynamics in elective cesarean under spinal anesthesia.

Phenylephrine vs ephedrine in cesarean delivery under spinal anesthesia: A systematic literature review and meta-analysis

BACKGROUND

In the past 20 years, many studies compared phenylephrine with ephedrine to prevent or treat hypotension in elective or emergency cesarean delivery and parturients with pre-eclampsia. A meta-analysis of the abovementioned trials is needed.

METHODS

Several databases (PubMed, Embase, Web of Science and Cochrane Library) were searched from inception to April 2018 for trials comparing phenylephrine with ephedrine in cesarean delivery. The primary outcome is the incidence of maternal hypotension.

RESULTS

Thirty-six trials (2439 patients) with elective cesarean delivery, three trials (400 patients) with emergency cesarean delivery and three trials (192 patients) with parturients with pre-eclampsia were included and analyzed. The incidence of hypotension did not differ in the elective surgery group (relative risk 0.83, 95% CI 0.66 to 1.05), emergency surgery group (relative risk 1.02, 95% CI 0.87 to 1.19) and pre-eclamptic parturients group (relative risk 0.93, 95% CI 0.63 to 1.37). The phenylephrine group had a higher incidence of bradycardia and lower incidences of tachycardia and nausea or vomiting in all three patient groups. The phenylephrine group also had lower fetal acidosis rate, higher umbilical artery and vein pH values and less base excess in the elective surgery. The abovementioned outcomes were similar in the emergency surgery group and the pre-eclampsia group. Publication bias for hypotension was detected. However, the trim and fill method demonstrated that the publication bias had little impact on hypotension. Trial sequential analysis of hypotension in elective surgery showed that this meta-analysis lacked a sufficient cumulative sample size and that further studies should be included.

CONCLUSION

Phenylephrine and ephedrine were both effective in maintaining hemodynamic balance. Newborns benefited more from phenylephrine in elective cesarean delivery, but not in emergency cesarean delivery or in parturients with pre-eclampsia. More trials should be included to achieve more conclusive results.

Norepinephrine versus Ephedrine to Maintain Arterial Blood Pressure during Spinal Anesthesia for Cesarean Delivery: A Prospective Double-blinded Trial

Background:

Ephedrine was conventionally regarded as the first-choice drug to maintain maternal blood pressure during spinal anesthesia for cesarean delivery, due to its stimulant activity on α- and β-adrenergic receptors. Norepinephrine is a weak β-adrenergic and potent α-adrenergic receptor agonist. Therefore, it may be suitable for maintaining blood pressure with less chronotropic effects compared to ephedrine.

Patients and Methods:

One hundred and forty healthy patients having cesarean delivery under spinal anesthesia were randomized to Group N (n = 61) who received a prophylactic bolus of norepinephrine 5 μg intravenous (i.v.) at the time of intrathecal block or Group E (n = 61) who received a prophylactic bolus of i.v. ephedrine 10 mg. Rescue i.v. bolus interventions of norepinephrine 5 μg or ephedrine 10 mg were given as required to maintain systolic blood pressure. Maternal and fetal hemodynamic variables, Apgar score, and number of boluses of vasopressors used were recorded.

Results:

The numbers of maternal hypotension and hypertension episodes and the frequency of bradycardia and tachycardia were significantly lower in Group N compared with Group E (P = 0.02, 0.003, 0.0002, and 0.008, respectively). The number of boluses of vasopressors used was also lower in Group N (P = 0.005). Uterine artery pulsatility index was lower in Group N compared to Group E (P = 0.01) when measured 5 min after spinal anesthesia. Moreover, it was higher at 5 min in Group E when compared with the baseline readings in the same group (P = 0.001).

Conclusions:

Norepinephrine is a suitable and potent drug to counterbalance the hemodynamic effects of spinal anesthesia during cesarean delivery.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

BACKGROUND

Maternal hypotension is the most frequent complication of spinal anaesthesia for caesarean section. It can be associated with nausea or vomiting and may pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis, neurological injury).

OBJECTIVES

To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register (9 August 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials, including full texts and abstracts, comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section. We excluded studies if hypotension was not an outcome measure.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study quality and extracted data from eligible studies. We report 'Summary of findings' tables using GRADE.

MAIN RESULTS

We included 126 studies involving 9565 participants. Interventions were to prevent maternal hypotension following spinal anaesthesia only, and we excluded any interventions considered active treatment. All the included studies reported the review's primary outcome. Across 49 comparisons, we identified three intervention groups: intravenous fluids, pharmacological interventions, and physical interventions. Authors reported no serious adverse effects with any of the interventions investigated. Most trials reported hypotension requiring intervention and Apgar score of less than 8 at five minutes as the only outcomes. None of the trials included in the comparisons we describe reported admission to neonatal intensive care unit. Crystalloid versus control (no fluids)Fewer women experienced hypotension in the crystalloid group compared with no fluids (average risk ratio (RR) 0.84, 95% confidence interval (CI) 0.72 to 0.98; 370 women; 5 studies; low-quality evidence). There was no clear difference between groups in numbers of women with nausea and vomiting (average RR 0.19, 95% CI 0.01 to 3.91; 1 study; 69 women; very low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (60 babies, low-quality evidence). Colloid versus crystalloidFewer women experienced hypotension in the colloid group compared with the crystalloid group (average RR 0.68, 95% CI 0.58 to 0.80; 2105 women; 28 studies; very low-quality evidence). There were no clear differences between groups for maternal hypertension requiring intervention (average RR 0.64, 95% CI 0.09 to 4.46, 3 studies, 327 women;very low-quality evidence), maternal bradycardia requiring intervention (average RR 0.99, 95% CI 0.55 to 1.79, 6 studies, 509 women; very low-quality evidence), nausea and/or vomiting (average RR 0.83, 95% CI 0.61 to 1.13, 15 studies, 1154 women, I² = 37%; very low-quality evidence), neonatal acidosis (average RR 0.83, 95% CI 0.15 to 4.52, 6 studies, 678 babies; very low-quality evidence), or Apgar score of less than 8 at five minutes (average RR 0.24, 95% CI 0.03 to 2.05, 11 studies, 826 babies; very low-quality evidence). Ephedrine versus phenylephrineThere were no clear differences between ephedrine and phenylephrine groups for preventing maternal hypotension (average RR 0.92, 95% CI 0.71 to 1.18; 401 women; 8 studies; very low-quality evidence) or hypertension (average RR 1.72, 95% CI 0.71 to 4.16, 2 studies, 118 women, low-quality evidence). Rates of bradycardia were lower in the ephedrine group (average RR 0.37, 95% CI 0.21 to 0.64, 5 studies, 304 women, low-quality evidence). There was no clear difference in the number of women with nausea and/or vomiting (average RR 0.76, 95% CI 0.39 to 1.49, 4 studies, 204 women, I² = 37%, very low-quality evidence), or babies with neonatal acidosis (average RR 0.89, 95% CI 0.07 to 12.00, 3 studies, 175 babies, low-quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (321 babies; low-quality evidence). Ondansetron versus controlOndansetron administration was more effective than control (placebo saline) for preventing hypotension requiring treatment (average RR 0.67, 95% CI 0.54 to 0.83; 740 women, 8 studies, low-quality evidence), bradycardia requiring treatment (average RR 0.49, 95% CI 0.28 to 0.87; 740 women, 8 studies, low-quality evidence), and nausea and/or vomiting (average RR 0.35, 95% CI 0.24 to 0.51; 653 women, 7 studies, low-quality evidence). There was no clear difference between the groups in rates of neonatal acidosis (average RR 0.48, 95% CI 0.05 to 5.09; 134 babies; 2 studies, low-quality evidence) or Apgar scores of less than 8 at five minutes (284 babies, low-quality evidence). Lower limb compression versus controlLower limb compression was more effective than control for preventing hypotension (average RR 0.61, 95% CI 0.47 to 0.78, 11 studies, 705 women, I² = 65%, very low-quality evidence). There was no clear difference between the groups in rates of bradycardia (RR 0.63, 95% CI 0.11 to 3.56, 1 study, 74 women, very low-quality evidence) or nausea and/or vomiting (average RR 0.42 , 95% CI 0.14 to 1.27, 4 studies, 276 women, I² = 32%, very-low quality evidence). No baby had an Apgar score of less than 8 at five minutes in either group (130 babies, very low-quality evidence). Walking versus lyingThere was no clear difference between the groups for women with hypotension requiring treatment (RR 0.71, 95% CI 0.41 to 1.21, 1 study, 37 women, very low-quality evidence).Many included studies reported little to no information that would allow an assessment of their risk of bias, limiting our ability to draw meaningful conclusions. GRADE assessments of the quality of evidence ranged from very low to low. We downgraded evidence for limitations in study design, imprecision, and indirectness; most studies assessed only women scheduled for elective caesarean sections.External validity also needs consideration. Readers should question the use of colloids in this context given the serious potential side effects such as allergy and renal failure associated with their administration.

AUTHORS' CONCLUSIONS

While interventions such as crystalloids, colloids, ephedrine, phenylephrine, ondansetron, or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension in some women. We cannot draw any conclusions regarding rare adverse effects associated with use of the interventions (for example colloids) due to the relatively small numbers of women studied.

Goal-directed Fluid Therapy May Improve Hemodynamic Stability of Parturient with Hypertensive Disorders of Pregnancy Under Combined Spinal Epidural Anesthesia for Cesarean Delivery and the Well-being of Newborns

Background:

Hypotension induced by combined spinal epidural anesthesia in parturient with hypertensive disorders of pregnancy (HDP) can easily compromise blood supply to vital organs including uteroplacental perfusion and result in fetal distress. The aim of this study was to investigate whether the goal-directed fluid therapy (GDFT) with LiDCO_rapid system can improve well-being of both HDP parturient and their babies.

Methods:

Fifty-two stable HDP parturient scheduled for elective cesarean delivery were recruited. After loading with 10 ml/kg lactated Ringer's solution (LR), parturient were randomized to the GDFT and control group. In the GDFT group, individualized fluid therapy was guided by increase in stroke volume (ΔSV) provided via LiDCO_rapid system. The control group received the routine fluid therapy. The primary endpoints included maternal hypotension and the doses of vasopressors administered prior to fetal delivery. The secondary endpoints included umbilical blood gas abnormalities and neonatal adverse events.

Results:

The severity of HDP was similar between two groups. The total LR infusion (P < 0.01) and urine output (P < 0.05) were higher in the GDFT group than in the control group. Following twice fluid challenge tests, the systolic blood pressure, mean blood pressure, cardiac output and SV in the GDFT group were significantly higher, and the heart rate was lower than in the control group. The incidence of maternal hypotension and doses of phenylephrine used prior to fetal delivery were significantly higher in the control group than in the GDFT group (P < 0.01). There were no differences in the Apgar scores between two groups. In the control group, the mean values of pH in umbilical artery/vein were remarkably decreased (P < 0.05), and the incidences of neonatal hypercapnia and hypoxemia were statistically increased (P < 0.05) than in the GDFT group.

Conclusions:

Dynamic responsiveness guided fluid therapy with the LiDCO_rapid system may provide potential benefits to stable HDP parturient and their babies.

Practice Guidelines for Obstetric Anesthesia

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology present an updated report of the Practice Guidelines for Obstetric Anesthesia.

Supplemental Digital Content is available in the text.

The effects on Apgar scores and neonatal outcomes of switching from a combination of phenylephrine and ephedrine to phenylephrine alone as a prophylactic vasopressor during spinal anesthesia for cesarean section

Background

Ephedrine, unlike phenylephrine, has a dose-related propensity to depress fetal pH during spinal anesthesia during cesarean section. A low arterial umbilical cord pH has a strong association with neonatal mortality and morbidity. The purpose of this retrospective study was to investigate influences of vasopressor change on Apgar scores and adverse neonatal outcomes in cesarean section.

Methods

In obstetric anesthesia, we changed the prophylactic vasopressor from a combination of phenylephrine and ephedrine to phenylephrine alone in 2000. We evaluated the impact of vasopressor change on Apgar scores (1 and 5 min), incidence of Apgar score < 7 (1 and 5 min), neonatal seizure, continuous positive airway pressure (CPAP), intermittent positive pressure ventilation (IPPV), intraventricular hemorrhage (IVH), periventricular leucomalacia (PVL), and hypoxic ischemic encephalopathy (HIE) in low-risk elective cesarean sections during a period when the combination of phenylephrine and ephedrine was used (2008-2009, two years) and the period of phenylephrine use alone (2011-2012, two years).

Results

There were no differences in Apgar scores (1 and 5 min), the incidence of 5 min Apgar score < 7, neonatal seizure, CPAP, IPPV, IVH, PVL, and HIE between the two time periods. However, the incidence of 1 min Apgar < 7 was decreased during the period of phenylephrine use compared with the period of phenylephrine and ephedrine use (P = 0.002).

Conclusions

Conversion from a combination of phenylephrine and ephedrine to phenylephrine alone as a prophylactic anti-hypotensive drug during spinal anesthesia for cesarean section in low-risk pregnancy may be associated with a significant decrease in the incidence of 1 min Apgar < 7.

Colloid cohydration and variable rate phenylephrine infusion effectively prevents postspinal hypotension in elective Cesarean deliveries

Background:

Prevention of post-spinal hypotension in obstetric patients can be accomplished using intravenous fluid expansion and prophylactic use of sympathomimetic drugs. The affect of combination of colloids and phenylephrine infusion on maternal hemodynamics has not been widely studied and there is no consensus about the dosage required and time of starting its administration.

Materials and Methods:

This prospective, randomized, double-blind study enrolled 90 healthy term parturients undergoing elective Cesarean delivery under lumbar subarachnoid block (0.5% hyperbaric bupivacaine 10 mg with fentanyl 25 μg). Patients in Group A received prophylactic intravenous phenylephrine infusion (60 μg/minute) along with hydroxyl-ethyl-starch cohydration (6% HES 130/0.42;15 ml/kg) immediately after subarachnoid block. In Group B, patients received 6% HES cohydration and intermittent intravenous 50 μg boluses of phenylephrine. The efficacy of these in maintaining maternal SBP at 90-110% of baseline and neonatal well-being was evaluated.

Results:

In Group B, 75.5% of patients required rescue phenylephrine boluses to maintain SBP while maternal hemodynamics were well maintained in Group A and rescue drug was not needed. Reactive hypertension occurred in one patient (2.2%) and bradycardia in two patients (4.4%) in Group A. Six patients complained of nausea in Group B (13.3%) compared to one in Group A. All the newborns had normal Apgar scores and Umbilical arterial pH > 7.2.

Conclusion:

A combination of colloid cohydration and prophylactic phenylephrine infusion initiated at 60 μg/minute maintained maternal hemodynamics and neonatal well-being during Cesarean deliveries requiring minimum interventions by the anesthesiologist.

Ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean section: an updated meta-analysis

AIMS

A systematic literature review comparing the efficacy of ephedrine and phenylephrine for the management of spinal anesthesia-induced hypotension during Cesarean sections (C-sections) was published in 2002. A number of well-designed trials with controversial results have been published afterward. Therefore, an updated meta-analysis was necessary.

METHODS

The MEDLINE, EMBASE, and the Cochrane Library databases were searched (last search performed on September 26, 2011). Pooled risk ratio (RR) or standard mean difference (SMD) and their 95% confidence intervals (95% CI) were calculated for the incidence of intra-operative hypotension or umbilical blood pH values.

RESULTS

A total number of 15 trials and 742 parturients under elective C-sections were analyzed. When used to prevent hypotension, patients receiving ephedrine and phenylephrine did not differ significantly in the incidence of hypotension (RR = 1.22; 95% CI, 0.83-1.80), umbilical arterial pH values (SMD = -0.38; 95% CI, -1.67 to 0.92) or venous pH values (SMD = -0.18; 95% CI, -0.44 to 0.07). And administration routes did not affect the incidence of hypotension and umbilical blood pH values. When used to treat hypotension, patients given ephedrine and phenylephrine had comparable incidence of intra-operative hypotension (RR = 0.79; 95% CI, 0.40-1.56), while parturients receiving phenylephrine had neonates with higher umbilical arterial pH values (SMD = -1.32; 95% CI, -2.35 to -0.30) and venous pH values (SMD = -0.79; 95% CI, -1.09 to -0.49) than those given ephedrine.

CONCLUSION

Prophylactic use of ephedrine and phenylephrine were both effective in preventing maternal hypotension during C-section under spinal anesthesia; phenylephrine was superior to ephedrine in treating hypotension, evidenced by higher umbilical blood pH values.

Vasopressors for the management of hypotension after spinal anesthesia for elective caesarean section. Systematic review and cumulative meta-analysis

BACKGROUND

Phenylephrine use has been recommended over ephedrine for the management of hypotension after spinal anesthesia for elective caesarean section. The evidence for this is rather limited because in previous trials, pH was significantly lower after ephedrine, but absolute values were still within normal range. We pooled the available data to define maternal and neonatal effects of the two vasopressors.

METHODS

Literature was identified by a systematic search. Hypotension, hypertension, and bradycardia of the mothers, fetal acidosis defined as a pH < 7.20, and the continuous variables base excess (BE) and arterial pCO(2) of the neonates were recorded. Meta-analysis using the random effects model was performed, and the weighted mean difference (WMD) or risk ratio (RR), and 95% confidence interval (95% CI) were calculated.

RESULTS

The criteria for eligibility were fulfilled by 20 trials including 1069 patients. The RR of true fetal acidosis was 5.29 (95%CI 1.62-17.25, ) for ephedrine vs. phenylephrine (P = 0.006). BE values after ephedrine use were significantly lower than after phenylephrine (WMD -1.17; 95% CI -2.01 - -0.33). Umbilical artery pCO(2) did not differ. Mothers treated with ephedrine had a lower risk for bradycardia (RR 0.17; 95%CI 0.07-0.43; P = 0.004). No differences between vasopressors were observed for hypotension and hypertension.

CONCLUSIONS

Our analysis could clearly demonstrate a decreased risk of fetal acidosis associated with phenylephrine use. In addition with our findings for BE, this suggests a favorable effect of phenylephrine on fetal outcome parameters. The mechanism of pH depression is not related to pCO(2) .

A sequential compression mechanical pump to prevent hypotension during elective cesarean section under spinal anesthesia

BACKGROUND

Spinal anesthesia is a standard technique for cesarean section but can cause hypotension which may be related to venous pooling secondary to progesterone-induced decreases in vascular tone. This study investigated the use of a sequential compression mechanical pump with thigh-high sleeves with compression cycles timed to venous refilling. We hypothesized that this would recruit pooled venous blood from the lower limbs, maintain the central blood volume and thus decrease the incidence of hypotension.

METHODS

One hundred parturients scheduled for elective cesarean section under spinal anesthesia were recruited and randomly assigned to use of either a mechanical pump (Group M) or control (Group C). A standardized protocol for co-hydration and anesthesia was followed. Hypotension, defined as a decrease in systolic blood pressure by >20% from baseline, was treated with 6-mg boluses of intravenous ephedrine. The incidence of hypotension was defined as the primary outcome. Median ephedrine requirement was taken as a measure of the severity of hypotension.

RESULTS

Hypotension occurred in 12 of 47 (25.5%) patients in Group M compared to 27 of 45 (60%) in Group C (P=0.001). The median [range] ephedrine dose was greater in Group C (12 [0-24]mg) compared to Group M (0 [0-12]mg) (P<0.001). There was no difference between groups in the time to onset of hypotension.

CONCLUSION

The use of a sequential compression mechanical pump that detects venous refilling and cycles accordingly, reduced the incidence and severity of hypotension after spinal anesthesia for cesarean section.

A review of the impact of phenylephrine administration on maternal hemodynamics and maternal and neonatal outcomes in women undergoing cesarean delivery under spinal anesthesia

Phenylephrine is effective for the management of spinal anesthesia-induced hypotension in parturients undergoing cesarean delivery under spinal anesthesia. While ephedrine was previously considered the vasopressor of choice in obstetric patients, phenylephrine is increasingly being used. This is largely due to studies suggesting improved fetal acid-base status with the use of phenylephrine as well as the low incidence of hypotension and its related side effects with prophylactic phenylephrine regimens. This review highlights the effects of phenylephrine compared with ephedrine on maternal hemodynamics (arterial blood pressure, heart rate, and cardiac output), and occurrence of intraoperative nausea and vomiting. The impact of the administration of phenylephrine as a bolus for the treatment of established hypotension compared with its administration as a prophylactic infusion is discussed. This article also reviews the impact of phenylephrine compared with ephedrine on uteroplacental perfusion, and fetal outcomes such as neonatal acid-base status and Apgar scores. The optimum dosing regimen for phenylephrine administration is also discussed.

[Anesthesiological management of Caesarean sections : nationwide survey in Germany]

BACKGROUND

The rate of Caesarean sections in Germany continues to rise. The change in anesthetic technique of choice from general to spinal anesthesia began later than in other countries and at the last survey in 2002 was not widely established. The literature on the anesthetic management of Caesarean sections contains many controversies, for example fluid preload before performing spinal anesthesia and the vasopressor of choice. Other issues have received relatively little attention, such as the level of experience of anesthesiologists working autonomously on the labour ward or the timing of antibiotic prophylaxis. The aim of the current survey was to provide an updated overview of anesthetic management of Caesarean sections in Germany.

MATERIAL AND METHODS

A questionnaire was sent out to 709 departments of anesthesiology serving obstetric units in Germany. The questionnaire concerned various aspects of anesthetic management of Caesarean sections.

RESULTS

A total of 360 questionnaires (50.8%) were returned of which 346 were complete and could be analyzed, accounting for 330,000 births and 90,000 Caesarean sections per year. The predominant anesthetic method used for Caesarean sections was spinal anesthesia (90.8%) using hyperbaric bupivacaine and in approximately one third of the hospitals surveyed without administering intrathecal opioids. Approximately 12% of the departments surveyed used traumatic Quincke needles. In 86.2% the vasopressor of choice was caffedrine/theodrenaline. Nitrous oxide was used in only 19.2% of departments surveyed when general anesthesia is performed. An antibiotic drug was administered in only 11% of hospitals before cord clamping. In 43.1% no neonatologist was available to treat unexpected critically ill newborns. In 32.1% of departments surveyed residents with less than 2 years experience worked autonomously on the labour ward.

CONCLUSIONS

Currently the predominant anesthetic technique of choice in Germany is spinal anaesthesia and at a much higher rate than in 2002. In addition 12% of departments use traumatic Quincke needles which are associated with a higher incidence of postpuncture headache. Nitrous oxide is no longer frequently used in Germany. Finally, the administration of an antibiotic before cord clamping has been shown to lead to lower rates of endometritis and postoperative wound infection without detrimental effects on the newborn. This is practiced in only a small minority of departments across Germany.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

BACKGROUND

Maternal hypotension, the most frequent complication of spinal anaesthesia for caesarean section, can be associated with severe nausea or vomiting which can pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis and neurological injury).

OBJECTIVES

To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2005).

SELECTION CRITERIA

Randomised controlled trials comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed eligibility and methodological quality of studies, and extracted data.

MAIN RESULTS

We included 75 trials (a total of 4624 women). Crystalloids were more effective than no fluids (relative risk (RR) 0.78, 95% confidence interval (CI) 0.60 to 1.00; one trial, 140 women, sequential analysis) and colloids were more effective than crystalloids (RR 0.68, 95% CI 0.52 to 0.89; 11 trials, 698 women) in preventing hypotension following spinal anaesthesia at caesarean section. No differences were detected for different doses, rates or methods of administering colloids or crystalloids. Ephedrine was significantly more effective than control (RR 0.51, 95% CI 0.33 to 0.78; seven trials, 470 women) or crystalloid (RR 0.70, 95% CI 0.50 to 0.96; four trials, 293 women) in preventing hypotension. No significant differences in hypotension were seen between ephedrine and phenylephrine (RR 0.95, 95% CI 0.37 to 2.44; three trials, 97 women) and phenylephrine was more effective than controls (RR 0.27, 95% CI 0.16 to 0.45; two trials, 110 women). High rates or doses of ephedrine may increase hypertension and tachycardia incidence. Lower limb compression was more effective than control (no leg compression) (RR 0.69, 95% CI 0.53 to 0.90; seven trials, 399 women) in preventing hypotension, although different methods of compression appeared to vary in their effectiveness. No other comparisons between different physical methods such as position were shown to be effective, but these trials were often small and thus underpowered to detect true effects should they exist.

AUTHORS' CONCLUSIONS

While interventions such as colloids, ephedrine, phenylephrine or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension during spinal anaesthesia for caesarean section. No conclusions can be drawn regarding rare adverse effects due to the relatively small numbers of women studied.