Comparison of effects of rapid colloid loading before and after spinal anesthesia on maternal hemodynamics and neonatal outcomes in cesarean section

Association of infraclavicular axillary vein diameter and collapsibility index with general anesthesia-induced hypotension in elderly patients undergoing gastrointestinal surgery: an observational study

BACKGROUND

The collapse index of inferior Vena Cava (IVC) and its diameter are important predictive tools for fluid responsiveness in patients, especially critically ones. The collapsibility of infraclavicular axillary vein (AXV) can be used as an alternative to the collapsibility of IVC (IVC-CI) to assess the patient's blood volume.

METHODS

A total of 188 elderly patients aged between 65 and 85 years were recruited for gastrointestinal surgery under general anesthesia. Ultrasound measurements AXV and IVC were performed before induction of general anesthesia. Patients were grouped in accordance to the hypotension after induction. ROC curves were used to analyze the predictive value of ultrasound measurements of AXV and IVC for hypotension after induction of anesthesia. Pearson linear correlation was used to assess the correlation of ultrasound measurements and decrease in mean arterial blood pressure (MAP).

RESULTS

The maximum diameter of AXV(dAXVmax) and the maximum diameter of IVC (dIVCmax) were not related to the percentage decrease in MAP; the collapsibility of AXV (AXV-CI) and IVC-CI were positively correlated with MAP changes (correlation coefficients:0.475, 0.577, respectively, p < 0.001). The areas under the curve (AUC) was 0.824 (0.759-0.889) for AXV-CI, and 0.874 (0.820-0.928) for IVC-CI. The optimal threshold for AXV-CI was 31.25% (sensitivity 71.7%, specificity 90.1%), while for IVC-CI was 36.60% (sensitivity 85.9%, specificity 79.0%). Hypotension and down-regulation of MAP during induction can be accurately predicted by AXV-Cl after correction for confounding variables.

CONCLUSION

Infraclavicular axillary vein diameter has no significant correlation with postanesthesia hypotension, whereas AXV-CI may predict postanesthesia hypotension during gastrointestinal surgery of the elderly.

TRIAL REGISTRATION

This study was registered in the Clinical Trial Registry of China on 05/06/2022 (ChiCTR2200060596).

Preliminary study on fluid bolus administration for prevention of spinal hypotension in dogs undergoing elective cesarean section

Introduction

This study aimed to investigate the effect of fluid bolus administration during epidural anesthesia (coload) in female dogs scheduled for elective cesarean section (CS). Hypotension is one of the most common complications of epidural (EA) and spinal (SA) analgesia, and in the case of cesarean section, it may pose a significant risk for placental perfusion and subsequent fetal vitality and puppy survival.

Methods

Pregnant bitches scheduled for elective CS underwent EA with (treatment group) or without (control group) intravenous fluid bolus administration. The following parameters were measured and compared between both groups: HR, RR, etCO₂, SpO₂, systolic, diastolic and mean arterial blood pressure were measured at three time points (T1: before surgery, T2: after the last puppy removal, and T3: end of surgery) in dams; vitality (Apgar score at 0, 5, and 20 min) and umbilical cord blood parameters (pH, pCO2, HCO3, base excess, lactate and glucose) in newborns.

Results

The results indicated that crystalloid coloading increased maternal systolic, diastolic, and mean blood pressure (treatment vs. control group, 101.46 ± 9.18, 48.01 ± 13.47, and 67.07 ± 13.15 mmHg vs. 80.68 ± 7.29, 36.52 ± 8.75, and 180 52.30 ± 7.77, p < 0.05) with significantly fewer episodes of hypotension. Additionally, puppies in the treatment group received higher scores in the 5-min (7.91 ± 1.67 vs. 6.74 ± 2.20) and 20-min (9.38 ± 0.87 vs. 8.39 ± 2.50) assessments without the favorable effect on umbilical blood gas parameters.

Discussion

Based on the obtained results, it can be stated that crystalloid coload offers an effective option in cases of hypotension during cesarean section, with clear benefits for both mothers and newborns.

Effect of Crystalloid or Colloid Fluid Loading and Vasopressor Pre-Treatment on the Timing of Hypotension in Cesarean Section with Subarachnoid Block

BACKGROUND: Cesarean section (C-section) is the most frequently performed surgery in obstetrics, generally using subarachnoid block (SAB) or epidural block for anesthesia. The previous studies have shown the effectiveness of fluid loading and vasopressor pretreatment in preventing maternal hypotension (decreased blood pressure), the most common side effect of SAB. However, the timing of hypotension in response to these treatments has not been analyzed. AIM: This study therefore aimed to compare the effects of crystalloid or colloid fluid loading and vasopressor pre-treatment on the timing of hypotension in cases of C-section under SAB anesthesia. METHODS: The study was a single-blind randomized controlled clinical trial with three treatment groups: Group I, 10 mL/kgBW crystalloid solution (Ringer’s lactate) loading 10 min before SAB; Group II, 5 mL/kgBW colloid fluid (gelatin) loading 10 min before SAB; and Group III, pretreatment with 0.1 mg/kgBW vasopressor (ephedrine) intravenous bolus just before SAB. RESULTS: Significant differences in mean blood pressure between groups were observed between the second and 8th min (p < 0.05). Hypotension was observed in the crystalloid group within the first 5 min, while average blood pressure was relatively stable all groups after the first 10 min. In addition, hypotension occurred more frequently in the crystalloid group (nine subjects, 45%), compared with the colloid and vasopressor groups (two subjects per group, 10%; p < 0.05). CONCLUSION: Hypotension occurred more rapidly and more frequently when crystalloid loading was utilized, compared with colloid loading or vasopressor pretreatment. Administration of colloid fluid loading and vasopressor pretreatment has been shown to prevent hypotension in SAB anesthesia.

Fluid loading therapy to prevent spinal hypotension in women undergoing elective caesarean section: Network meta-analysis, trial sequential analysis and meta-regression

BACKGROUND

Fluid loading is one of the recognised measures to prevent hypotension due to spinal anaesthesia in women scheduled for a caesarean section.

OBJECTIVE

We aimed to evaluate the current evidence on fluid loading in the prevention of spinal anaesthesia-induced hypotension.

DESIGN

Systematic review and network meta-analysis with trial sequential analysis and meta-regression.

DATA SOURCES

Medline, Epub, Embase.com (Embase and Medline), Cochrane Central, Web of Science and Google Scholar were used.

ELIGIBILITY CRITERIA

Only randomised controlled trials were used. Patients included women undergoing elective caesarean section who received either crystalloid or colloid fluid therapy as a preload or coload. The comparator was a combination of either a different fluid or time of infusion.

RESULTS

A total of 49 studies (4317 patients) were included. Network meta-analysis concluded that colloid coload and preload offered the highest chance of success (97 and 67%, respectively). Conventional meta-analysis showed that crystalloid preload is associated with a significantly higher incidence of maternal hypotension than colloid preload: risk ratio 1.48 (95% CI 1.29 to 1.69, P < 0.0001, I² = 60%). However, this result was not supported by Trial Sequential Analysis. There was a significant dose–response effect for crystalloid volume preload (regression coefficient = −0.073), which was not present in the analysis of only double-blind studies. There was no dose–response effect for the other fluid regimes.

CONCLUSION

Unlike previous meta-analysies, we found a lack of data obviating an evidence-based recommendation. In most studies, vasopressors were not given prophylactically as is recommended. Studies on the best fluid regimen in combination with prophylactic vasopressors are needed. Due to official european usage restrictions on the most studied colloid (HES), we recommend crystalloid coload as the most appropriate fluid regimen.

TRIAL REGISTRATION

CRD42018099347.

Effects of colloid preload on the incidence of hypotension in spinal anesthesia for cesarean section: a systematic review and meta-analysis

Background:

Hypotension is a common complication caused by spinal anesthesia (SA), which may have adverse impacts on the condition of the parturient and fetus. Liquid infusion was found to be relatively effective for reducing the incidence of hypotension. However, the question of whether colloid preload can optimize hemodynamic variables in the cesarean section remains controversial. This study aims to determine the effects of colloid preload on the incidence of hypotension induced by SA in elective cesarean section.

Methods:

Related keywords were searched on PubMed, EMBASE, and Cochrane Library from inception dates to May 2020. Studies included were evaluated for eligibility and quality. The primary outcome was the intra-operative incidence of hypotension and severe hypotension. The secondary outcomes included the lowest intra-operative systolic blood pressure, the maximal intra-operative heart rate, the intra-operative needs of ephedrine and phenylephrine, the incidence of maternal nausea and/or vomiting, and neonatal outcomes (umbilical artery pH and Apgar scores). Apart from the above, RevMan 5.3 was used for the data analysis.

Results:

Altogether nine randomized controlled trials were included in the meta-analysis. There were no significant differences in the incidence of intra-operative hypotension, severe hypotension, or neonatal outcomes between the colloid preload group and control group, except for the umbilical artery pH.

Conclusion:

This meta-analysis suggests that colloid preload does not significantly reduce the incidence of hypotension associated with SA in elective cesarean section.

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.

Prevention of hypotension after spinal anaesthesia for caesarean section: a systematic review and network meta-analysis of randomised controlled trials

Spinal anaesthesia for caesarean section commonly causes maternal hypotension. This systematic review and network meta-analysis compared methods to prevent hypotension in women receiving spinal anaesthesia for caesarean section. We selected randomised controlled trials that compared an intervention to prevent hypotension with another intervention or inactive control by searching MEDLINE and Embase, Web of Science to December 2018. There was no language restriction. Two reviewers extracted data on trial characteristics, methods and outcomes. We assessed risk of bias for individual trials (Cochrane tool) and quality of evidence (GRADE checklist). We assessed 109 trials (8561 women) and 12 different methods that resulted in 30 direct comparisons. Methods ranked by OR (95%CI) from most effective to least effective were: metaraminol 0.11 (0.04-0.26); norepinephrine 0.13 (0.06-0.28); phenylephrine 0.18 (0.11-0.29); leg compression 0.25 (0.14-0.43); ephedrine 0.28 (0.18-0.43); colloid given before induction of anaesthesia 0.38 (0.24-0.61); angiotensin 2, 0.12 (0.02-0.75); colloid given after induction of anaesthesia 0.52 (0.30-0.90); mephentermine 0.09 (0.01-1.30); crystalloid given after induction of anaesthesia 0.78 (0.46-1.31); and crystalloid given before induction of anaesthesia 1.16 (0.76-1.79). Phenylephrine caused maternal bradycardia compared with control, OR (95%CI) 0.23 (0.07-0.79). Ephedrine lowered umbilical artery pH more than phenylephrine, standardised mean difference (95%CI) 0.78 (0.47-1.49). We conclude that vasopressors should be given to healthy women to prevent hypotension during caesarean section with spinal anaesthesia.

Effect of Glucose Containing Crystalloid Infusion on Maternal Hemodynamic Status After Spinal Anesthesia for Cesarean Section

Background

Despite preventive strategies, hypotension is the most common complication of spinal anesthesia in cesarean section.

Objectives

The aim of this study was to assess the effect of glucose-containing crystalloid infusion on maternal hemodynamic status after spinal anesthesia for cesarean section.

Methods

In this prospective, randomized, double-blind clinical trial, 80 parturients undergoing elective cesarean section with spinal anesthesia were studied. In group A (n = 40) ringer with 1% glucose solution (10 gr glucose in 1000 mL ringer) and in group B (n = 40) only ringer solution infused before and after spinal anesthesia. Demographic data, hemodynamic change, complications and their treatments, maternal blood sugar level and neonatal APGAR (appearance, pulse, grimace, activity and respiration) score, intraoperative fluid, duration of surgery, and anesthesia were recorded in the two groups.

Results

The incidence of hypotension in group A was significantly lower than group B (27.5% vs 75%) (P = 0.002). Other complications (sustained hypotension, nausea, pallor, and shivering were significantly lower in parturients of the group A (P < 0.05). Maternal blood sugar (BS), before and after surgery, was not significantly different in the two groups (P = 0.207 and P = 0.239, respectively). There was no statistically significant difference in the APGAR score of neonates at the 1st and 5th minutes of the birth between the two groups (P = 0.076).

Conclusions

It seems that adding 1% glucose to crystalloid solution improves the hemodynamic status and decreases post-spinal anesthesia complications without significant changes in the maternal blood sugar level and APGAR score of neonates.

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.

[Recent standards in management of obstetric anesthesia]

The following article contains information not only for the clinical working anaesthesiologist, but also for other specialists involved in obstetric affairs. Besides a synopsis of a German translation of the current "Practice Guidelines for Obstetric Anaesthesia 2016" [1], written by the American Society of Anesthesiologists, the authors provide personal information regarding major topics of obstetric anaesthesia including pre-anaesthesia patient evaluation, equipment and staff at the delivery room, use of general anaesthesia, peridural analgesia, spinal anaesthesia, combined spinal-epidural anaesthesia, single shot spinal anaesthesia, and programmed intermittent epidural bolus.

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.

Comparison of maternal and fetal outcomes among patients undergoing cesarean section under general and spinal anesthesia: a randomized clinical trial

CONTEXT AND OBJECTIVE

As the rates of cesarean births have increased, the type of cesarean anesthesia has gained importance. Here, we aimed to compare the effects of general and spinal anesthesia on maternal and fetal outcomes in term singleton cases undergoing elective cesarean section.

DESIGN AND SETTING

Prospective randomized controlled clinical trial in a tertiary-level public hospital.

METHODS

Our study was conducted on 100 patients who underwent cesarean section due to elective indications. The patients were randomly divided into general anesthesia (n = 50) and spinal anesthesia (n = 50) groups. The maternal pre and postoperative hematological results, intra and postoperative hemodynamic parameters and perinatal results were compared between the groups.

RESULTS

Mean bowel sounds (P = 0.036) and gas discharge time (P = 0.049) were significantly greater and 24th hour hemoglobin difference values (P = 0.001) were higher in the general anesthesia group. The mean hematocrit and hemoglobin values at the 24th hour (P = 0.004 and P < 0.001, respectively), urine volume at the first postoperative hour (P < 0.001) and median Apgar score at the first minute (P < 0.0005) were significantly higher, and the time that elapsed until the first requirement for analgesia was significantly longer (P = 0.042), in the spinal anesthesia group.

CONCLUSION

In elective cases, spinal anesthesia is superior to general anesthesia in terms of postoperative comfort. In pregnancies with a risk of fetal distress, it would be appropriate to prefer spinal anesthesia by taking the first minute Apgar score into account.

Comparison of hydroxyethyl starch 6% and crystalloids for preloading in elective caesarean section under spinal anesthesia

BACKGROUND

Although controversial, many studies have shown effectiveness of colloid loading as a substitute for crystalloids on reducing the incidence of hypotension in spinal anesthesia. This study was conducted to compare the effects of three intravenous fluid regimens on hemodynamic changes following spinal anesthesia in cesarean section. The regimens included 6% Hydroxyethylstarch 130/0.4 (HES) as a colloid and two crystalloids (lactated ringer's solution and sodium chloride 0.9%).

MATERIAL & METHOD

In a double-blind clinical trial, 90 otherwise healthy parturients candidate of elective caesarean section were randomly allocated to receive lactated ringer's solution (1000 ml), sodium chloride 0.9% (1000 ml) or HES (7.5 mL/Kg) as preloading before spinal anesthesia. Hemodynamic parameters including blood pressure and heart rate, umbilical cord blood pH and the neonatal Apgar score were compared among the three groups.

RESULTS

There was no difference in the basic hemodynamic measurements among the three groups. The incidence of hypotension and required dose of ephedrine was lower in HES group (p=0.008). There was no significant difference in umbilical cord blood PH or Apgar scores among intervention groups.

CONCLUSION

Preloading with HES is more effective than crystalloids in prevention hypotension after spinal anesthesia without significant difference in Apgar score and umblical cord blood pH.

Influence of the timing of administration of crystalloid on maternal hypotension during spinal anesthesia for cesarean delivery: preload versus coload

Background

Prophylactic fluid preloading before spinal anesthesia has been a routine procedure to prevent maternal hypotension during cesarean delivery. Unlike colloid, timing of infusion of crystalloid may be important because of its short stay in intravascular space. We hypothesized that crystalloid loading just after intrathecal injection compared to preload would be more effective in preventing maternal hypotension.

Methods

In this prospective controlled study, sixty parturients were randomized to receive 15 ml/kg of crystalloid before (preload group) or after (coload group) intrathecal drug injection for spinal anesthesia. Hypotension was defined if systolic arterial pressure decreased below 80% of baseline and ephedrine was administered to treat hypotension. The incidence of hypotension and the total dose of ephedrine were checked. Blood pressure, heart rate and nausea before childbirth were assessed. Neonatal outcomes were evaluated with Apgar scores and umbilical blood gas analysis.

Results

The incidence of hypotension was lower in the coload group compared to the preload group (53% vs. 83%, P = 0.026). The blood pressure showed the bigger drop during spinal anesthesia in the preload group (34 ± 13 vs. 25 ± 10 mmHg, P = 0.002) and smaller dose of ephedrine was required in the coload group (7.5 [0–30] vs. 15 [0–40] mg, P = 0.015). The incidence of nausea was also lower in the coload group (27% vs. 60%, P = 0.019). Neonatal outcome measures were comparable between two groups.

Conclusions

In case of using crystalloids for cesarean delivery, coload is more effective than preload for the prevention of maternal hypotension after spinal anesthesia.

Trial registration

Clinical Research Information Service KCT0000324 (Jan 12^th, 2012)

Colloid or crystalloid solution on maternal and neonatal hemodynamics for cesarean section: a meta-analysis of randomized controlled trials

AIM

To compare the effect of colloid and crystalloid on maternal and neonatal hemodynamics in cesarean section.

MATERIAL AND METHODS

We searched MEDLINE (PubMed, 1966-2011), EMBASE (1974-2011), http://www.clinicaltrials.gov, the Cochrane Controlled Clinical Trials Register Database, Biosis Preview, and the Chinese Biomedical Database (1980-2011). Randomized controlled trials involving healthy term patients undergoing scheduled cesarean delivery that compared the effect of colloid and crystalloid on hypotension, need for vasopressors, cardiac output, neonatal outcomes, and other adverse effects were analyzed.

RESULTS

Ten trials of 853 patients were eligible for analysis. When colloid was used, significantly fewer hypotensive events occurred (odds ratio [OR] 3.21, 95% CI 2.15-4.53, number needed to treat = 4), less demand for vasopressors (standard mean difference [SMD] 0.77, 95% CI 0.34-1.21) and improved cardiac output (SMD -1.08, 95% CI -2.00 - -0.17). In subgroup analysis, the use of colloid reduced hypotensive events and adverse effects in Asian patients.

CONCLUSION

Colloid hydration should be considered first, especially in Asian patients, focusing on dosage and type of fluids. Preventive or therapeutic vasopressors may be required in a significant proportion of patients.

Controversies in obstetric anesthesia

Obstetric anesthesia has become a widely evidence-based practice, with an increasing number of specialized anesthesiologists and a permanent research production. We believe that with the review of commonly discussed and controversial points the reader will be able to incorporate an evidence-based practice into their routine and offer to parturients and their babies a safe, reliable and consistent anesthesia care.

Fluid and vasopressor management for Cesarean delivery under spinal anesthesia: continuing professional development

PURPOSE

The purpose of this Continuing Professional Development module is to review the physiology of maternal hypotension induced by spinal anesthesia in pregnant women, and the effects of fluids and vasopressors.

PRINCIPAL FINDINGS

Maternal hypotension induced by spinal anesthesia is caused mainly by peripheral vasodilatation and is not usually associated with a decrease in cardiac output. Although the intravenous administration of fluids helps to increase cardiac output, it does not always prevent maternal hypotension. Three strategies of fluid administrations are equivalent for the prevention of maternal hypotension and a reduced need for vasopressors: (1) colloid preload; (2) colloid coload; and (3) crystalloid coload. Crystalloid preload is not as effective as any of those three strategies. Unlike phenylephrine, ephedrine can cause fetal acidosis. Therefore, phenylephrine is recommended as first line treatment of maternal hypotension. A phenylephrine infusion (25-50 μg x min(-1)) appears to be more effective than phenylephrine boluses to prevent hypotension, and nausea and vomiting. In pre-eclamptic patients, spinal anesthesia produces less hypotension than in normal pregnant women and fluid volumes up to 1,000 mL are usually well tolerated. Therefore mild to moderate intravascular volume loading is recommended, keeping in mind the increased risk for pulmonary edema in this population. In pre-eclamptic patients, hypotension can be treated either with ephedrine or phenylephrine, and phenylephrine infusions are not recommended.

CONCLUSION

A volume loading regimen other than crystalloid preload should be adopted. A phenylephrine infusion during elective Cesarean delivery is beneficial for the mother and safe for the newborn.

[Prophylaxis for hypotension during cesarean section under spinal anesthesia: a randomized trial comparing hydroxyethyl starch 130/0.4 to ephedrine]

BACKGROUND AND OBJECTIVE

Spinal anesthesia is the technique of choice for scheduled or emergency cesarean section, but the prevalence of hypotension is high in this setting. Our aim was to compare the efficacy of a colloid (6% hydroxyethyl starch [HES] 130/0.4) to ephedrine for preventing hypotension.

PATIENTS AND METHODS

Patients undergoing elective or emergency cesarean section (in non-life-threatening situations) were enrolled. Patients were randomized to 3 groups for prophylaxis. The first ephedrine group received 5 mg of ephedrine intravenously (EPHE-5); the second ephedrine group received 10 mg of the drug intravenously (EPHE-10); and the HES group received 500 mL of HES 130/0.4 in rapid infusion n 15 minutes. We recorded systolic and diastolic blood pressures and heart rate after 10 minutes in the operating room and 2, 5, 10, 15, 20, and 30 minutes after injection of the anesthetic. We also assessed the sensory and motor blockades on both sides 2, 5, 10, 15, 20, and 30 minutes after injection. Neonatal status was assessed by Apgar score and umbilical cord blood gas analysis.

RESULTS

Ninety-six patients, 33 in each ephedrine group and 30 in the HES group, were enrolled. Blood pressure decreased similarly in all 3 groups (36% EPHE-5 group, 36% EPHE-10 group and 40% HES group); no significant between-group differences were observed. Nor were there significant differences in the percentages of patients requiring bolus doses of ephedrine to treat hypotension (23% in the HES group vs 33% in the EPHE-5 group and 27% in the EPHE-10 group) or in the cumulative doses of ephedrine. Neonatal status was also similarly satisfactory in all 3 groups.

CONCLUSIONS

HES 130/0.4 is as useful for hypotension prophylaxis as 5-mg or 10-mg intravenous doses of ephedrine. HES 130/0.4 might be a substitute for sympathomimetic agents if adverse effects are predicted or contraindications to the use of such drugs are present.

Improvement of quality of reporting in randomised controlled trials to prevent hypotension after spinal anaesthesia for caesarean section

Hypotension is a frequent complication of spinal anaesthesia for caesarean section and can threaten the well-being of the unborn child. Numerous randomised controlled trials (RCTs) dealt with measures to prevent hypotension. The aim of this study was to determine the reporting quality of RCTs using the Consolidated Standards of Reporting Trials (CONSORT) statement since low quality can lend false credibility to a study and overestimate the effect of an intervention. We performed a systematic literature search in PubMed to identify relevant RCTs in a pre-CONSORT period (1990-1994) and a post-CONSORT period (2004-2008). A comparative evaluation was done between the two periods, and the trials were assessed for compliance with each of the 22 CONSORT items. A total of 37 RCTs was identified. The CONSORT score increased significantly (p < 0.05) from 66.7% (±12.5%) in the pre-CONSORT period to 87.4% (±6.9%) in the post-CONSORT period. A statistically significant improvement was found for eight items, including randomization, blinding and intention-to-treat analysis. The CONSORT score in the post-CONSORT era was fairly good, also in comparison to other medical fields. In the post-CONSORT era, reporting of important items improved, in particular in the domains that are crucial to avoid bias and to improve internal validity. Use of CONSORT should be encouraged in order to keep or even improve the reporting quality.

Definitions of hypotension after spinal anaesthesia for caesarean section: literature search and application to parturients

BACKGROUND

Spinal anaesthesia for caesarean section may cause hypotension, jeopardizing the foetus and its mother. We aimed to identify the spectrum of definitions of hypotension used in the scientific literature. In a second part, we applied these definitions to a prospective cohort in order to evaluate the effect of different definitions on the incidence of hypotension.

METHODS

A systematic literature search in PubMed was performed from 1999 to 2009 with the search terms 'hypotension' and 'caesarean section'. Consecutive parturients undergoing caesarean section under spinal anaesthesia were included in a prospective study.

RESULTS

Sixty-three eligible publications (7120 patients) were retrieved, revealing 15 different definitions of hypotension. A decrease below 80% baseline and the combined definition of a blood pressure below 100 mmHg or a decrease below 80% baseline were the two most frequent definitions, found in 25.4% and 20.6% of the papers, respectively. When applying the spectrum of definitions to a prospective cohort, the incidences of hypotension varied between 7.4% and 74.1%. The incidence increased from 26.7% to 38.5% when using a value below 75% of baseline instead of below 70% of baseline.

CONCLUSION

There is not one accepted definition of hypotension in the scientific literature. The incidence of hypotension varies depending on the chosen definition. Even minor changes of the definition cause major differences in the frequency of hypotension. This makes it difficult to compare studies on interventions to treat/prevent hypotension and probably hampers progress in this area of research.

Effects of Fluid Preload (Crystalloid or Colloid) Compared with Crystalloid Co-Load Plus Ephedrine Infusion on Hypotension and Neonatal Outcome during Spinal Anaesthesia for Caesarean Delivery

Preload with crystalloid or colloid solution is widely recommended for the prevention of maternal hypotension during spinal anaesthesia. A combination of simultaneous rapid crystalloid infusion with vasopressor has also been suggested. This study tested the hypothesis that ephedrine infusion with crystalloid loading at spinal anaesthesia would reduce hypotension and alter neonatal outcome compared with fluid preloading.

One hundred and twenty women undergoing elective caesarean delivery were randomly allocated to one of three groups to receive rapid infusion of lactated Ringer's solution (20 ml.kg-1, n=40) or 4% succinylated gelatin solution (500 ml, n=40) before spinal anaesthesia or an ephedrine infusion (1.25 mg.minute-1) plus lactated Ringer's solution (1000 ml, n=40) after spinal anaesthesia. The incidence of hypotension (moderate and severe) and the ephedrine dose used to treat hypotension were compared. Neonatal outcome was assessed using Apgar scores and umblical venous and arterial blood gas analysis.

The frequency of moderate or severe hypotension was lower in the ephedrine group than in the crystalloid or colloid preload group (10% vs 51% and 38%; 5% vs 21% and 23% respectively, P <0.05). The incidence of nausea was significantly different between the crystalloid preload and ephedrine group. Umbilical blood gas analysis and Apgar scores were similar in all groups.

A combination of an ephedrine infusion at 1.25 mg.minute-1 with a crystalloid co-load was more effective than fluid preloading with crystalloid or colloid in the prevention of moderate and severe hypotension.

A survey of the management of spinal-induced hypotension for scheduled cesarean delivery

BACKGROUND

Intravenous fluids and vasopressors are used for managing spinal-induced hypotension during cesarean delivery, but the choice of vasopressor and the type and timing of fluid administration remain controversial.

METHODS

We conducted an electronic survey of all members of the Society for Obstetric Anesthesia and Perinatology between February and March 2007 to determine their preferences for preventing and treating spinal-induced hypotension with respect to fluid and vasopressor administration.

RESULTS

The response rate was 292/746 (39%). Fifty percent worked in academic institutions and 56% had >50% of their clinical responsibility to obstetric anesthesia. For prophylaxis, 35% used fluid preloading, 30% fluid preloading with vasopressors, and 12% fluid co-loading with vasopressors. Of those using vasopressors for prophylaxis, 32% used ephedrine, 26% used phenylephrine, and 33% based their choice on heart rate. For treatment, 32% used ephedrine, 23% used phenylephrine, and 41% used either agent based on heart rate. Anesthesiologists in academic practice were less likely to use fluid preloading only (P=0.028) and more likely to use fluid co-loading and vasopressors (P=0.003). They were also more likely to administer phenylephrine for prophylaxis compared with those in private practice (P=0.042).

CONCLUSION

Significant variations in practice exist in the prevention and treatment of spinal-induced hypotension. Fluid preloading and the prophylaxis and treatment of hypotension with ephedrine continue to be common practices.

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.