The Effects of Varying Volumes of Crystalloid Administration Before Cesarean Delivery on Maternal Hemodynamics and Colloid Osmotic Pressure

Comparison of the effects of hydroxyethyl starch and succinylated gelatin infusion on the perfusion index in elective caesarean sections under spinal anaesthesia

Aim: This study is to compare the alterations of three different replacement fluids on Perfusion Index, Pleth Variability Index (PI, PVI) and hemodynamic data in cases planned to experience caesarean surgery under spinal anaesthesia. Material and Method: 94 ASAII class patients aged 18–40 that were planned to experience caesarean surgery were included in the study. The patients were divided into three groups according to the fluid replacement to be applied. Patients in Group H received 10 ml/kg of hydroxyethyl starch (HES) up to a maximum of 500 ml over 20 minutes. Patients in Group G got 10 ml/kg of modified liquid gelatin(GEL) up to a maximum of 500 ml over 20 minutes. Patients in Group I got 20 ml/kg of isotonic sodium chloride (0.9% NaCl) over 20 minutes. Routine monitoring and perfusion index, pleth variability index were recorded baseline and at the first, third and tenth min after spinal anaesthesia for all participants Results: A significant increase in the PI value over time was observed in Groups G and I (p=0.001*). According to the PVI results, the amount of decrease in Group G was statistically less than in the other two groups (p=0.015*). Conclusion: In conclusion, 0.9% NaCl and gelatine were more effective on PI in caesarean section under spinal anesthesia. Isotonic has a positive effect on both PI and PVI. We detected that PI increased compared to baseline values, and believe that this increase may a positive effect on tissue circulation in the patient.

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.

Comparative evaluation of pre-infusion at caesar section performed under spinal anesthesia. Results of multicenter trial

Abstact. Study of the effect of preinfusion, various infusion solutions on the state of hemodynamics, in patients undergoing a cesarean section performed under spinal anesthesia with 0.5 % solution of Longocain Heavy (0.5 % hyperbaric bupivacaine).Materials and methods. Spinal anesthesia (SAN) was performed in 2 190 women, aged 21 to 39 years, with a gestational age of 39 to 40 weeks. The structure of extragenital pathology was dominated by chronic anemia of varying severity – 1 650 (75.3 %), urinary tract infections – 756 (34.5 %), mild preeclampsia – 245 (11.2 %), chronic nonspecific lung diseases – 125 (5.7 %). 1 786 (81.5 %) patients underwent surgery in a planned manner, according to emergency indications – 404 (18.4 %). A combination of the two pathologies was observed in 852 (38.9 %) women. Indications for surgery were: disease of the operated uterus, insolvency of the scar on the uterus, clinically narrow pelvis, high-grade myopia, secondary labor weakness. The duration of surgery is ranged from 40 to 52 minutes.Results. In group I, the expressed hypotension, requiring sympathomimetic support with mezaton was observed in 192 (34.8 %) patients. In group II, severe hypotension requiring sympathomimetic support with mezaton was observed in 114 (20.8 %) patients. And in group III, hypotension requiring sympathomimetic support with mezaton was observed in 127 (23.2 %) patients. At that time, in patients of group IV severe hypotension, requiring sympathomimetic support with mezaton was observed in only 91 (18 %) cases.Conclusions. Neuraxial anesthesia is accompanied by the development of hypotension, which can be prevented by preinfusion with crystalloid solutions. Aggressive preinfusion of large volumes of isoosmolar crystalloids at a dose of 10–14 ml/kg was associated with an increase in the frequency of hemodynamic instability requiring sympathomimetic support.

Effect of anaesthetic technique on neonatal morbidity in emergency caesarean section for foetal distress

Background

While foetal distress is typically associated with ischaemic injury, few studies have assessed neonatal morbidity for emergency caesarean section. Moreover, the decision of the anaesthetic technique may be of paramount importance in emergency caesareans, because of the limited time and increased risk. We aimed to evaluate the effect of the anaesthetic technique on neonatal morbidity in emergency caesarean indicated for foetal distress.

Methods

This was a single-centre, prospective observational study, conducted between July-2015 and December-2015. The study enrolled parturient with indication for emergency caesarean section after diagnosis of foetal distress, who received either regional or general anaesthesia. The outcome measures were: 1, 5-minute Apgar scores; umbilical blood pH; length of hospitalization; and morbidity, defined as a 5-minute Apgar score <7, need for mechanical ventilation, admittance to a neonatal intensive care unit, or respiratory insufficiency symptoms.

Results

61 patients were included in the study, of whom 31 received regional anaesthesia. Neonatal morbidity was noted in 5 and 9 cases with regional and general anaesthesia, respectively. The 1-minute Apgar score was significantly lower(p = 0,045) for cases with general anaesthesia, which was not true for the 5-minute Apgar score. Regional anaesthesia was non-significantly associated with shorter length of hospitalization, lower incidence of morbidity, and higher umbilical blood pH. When we take regional anaesthesia cases as a reference point, we detected that general anaesthesia cases are showing 2,2 times more morbidity risk. But these results did not reach any statistically significant levels.

Conclusions

While we did find some improved results for regional anaesthesia group, we found no statistical evidence that neither anaesthesia technique is superior regarding neonatal morbidity. We think that regional anaesthesia should be preferred whenever possible because of our improved results of length of hospital stay, APGAR and morbidity and we think that general anaesthesia is indicated for very urgent cases or regional anaesthesia contraindicated patients.

Trial registration

http://www.isrctn.com/ISRCTN15181117

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.

Perfusion index as a predictor of hypotension following spinal anaesthesia in lower segment caesarean section

BACKGROUND AND AIMS

Perfusion index (PI) is a new parameter tried for predicting hypotension during spinal anaesthesia for the lower segment caesarean section (LSCS). This study aimed at investigating the correlation between baseline perfusion index and incidence of hypotension following SAB in LSCS.

METHODS

In this prospective observational study, 126 parturients were divided into two groups on the basis of baseline PI. Group I included parturients with PI of ≤3.5 and Group II, parturients with PI values >3.5. Spinal anaesthesia was performed with 10 mg of injection bupivacaine 0.5% (hyperbaric) at L3-L4 or L2-L3 interspace. Hypotension was defined as mean arterial pressure <65 mmHg. Statistical analysis was performed using Chi-square test, independent sample t-test and Mann-Whitney U-test. Regression analysis with Spearman's rank correlation coefficient was done to assess the correlation between baseline PI and hypotension. Receiver operating characteristic (ROC) curve was plotted for PI and occurrence of hypotension.

RESULTS

The incidence of hypotension in Group I was 10.5% compared to 71.42% in Group II (P < 0.001). There was significant correlation between baseline PI >3.5 and number of episodes of hypotension (r_s0.416, P < 0.001) and total dose of ephedrine (r_s0.567, P < 0.001). The sensitivity and specificity of baseline PI of 3.5 to predict hypotension was 69.84% and 89.29%, respectively. The area under the ROC curve for PI to predict hypotension was 0.848.

CONCLUSION

Baseline perfusion index >3.5 is associated with a higher incidence of hypotension following spinal anesthesia in elective LSCS.

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.

[Anesthetic management of severe or worsening postpartum hemorrhage]

INTRODUCTION

Risk factors of maternal morbidity and mortality during postpartum hemorrhage (PPH) include non-optimal anesthetic management. As the anesthetic management of the initial phase is addressed elsewhere, the current chapter is dedicated to the management of severe PPH.

METHODS

A literature search was performed using PubMed and Medline databases, and the Cochrane Library, for articles published from 2003 up to and including 2013. Several keywords related to anesthetic and critical care practice, and obstetrical management were used, in various combinations. Guidelines from several societies and organisations were also read.

RESULTS

When PPH worsens, one should ask for additional team personnel (professional consensus). Patients should be monitored for heart rate, blood pressure, skin and mucosal pallor, bleeding at skin puncture sites, diuresis and the volume of genital bleeding (grade B). Because of the possible rapid worsening of coagulapathy, patients should undergo regular evaluation of coagulation status (professional consensus). Prevention and management of hypothermia should be considered (professional consensus), by warming intravenous fluids and blood products, and by active body warming (grade C). Antibiotics should be given, if not already administered at the initial phase (professional consensus). Vascular fluids must be given (grade B), the choice being left at the physician discretion. Blood products transfusion should be decided based on the clinical severity of PPH (professional consensus). Priority is given to red blood cells (RBC) transfusion, with the aim to maintain Hb concentration>8g/dL. The first round of products could include 3 units of RBC (professional consensus), and the following round 3 units of RBC, and 3 units of fresh frozen plasma (FFP). The FFP:RBC ratio should be kept between 1:2 and 1:1 (professional consensus). Depending on the etiology of PPH, the early administration of FFP is left at the discretion of the physician (professional consensus). Platelet count should be maintained at>50 G/L (professional consensus). During massive PPH, fibrinogen concentration should be maintained at>2g/L (professional consensus). Fibrinogen can be given without prior fibrinogen measurement in case of massive bleeding (professional consensus). General anesthesia should be considered in case of hemodynamic instability, even when an epidural catheter is in place (professional consensus).

CONCLUSION

The anesthetic management aims to restore and maintain optimal respiratory state and circulation, to treat coagulation disorders, and to allow invasive obstetrical and radiologic procedures. Clinical and instrumental monitoring are needed to evaluate the severity of PPH, to guide the choice of therapeutic options, and to assess treatments efficacy.

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.

The median effective volume of crystalloid in preventing hypotension in patients undergoing cesarean delivery with spinal anesthesia

BACKGROUND AND OBJECTIVES

Spinal anesthesia-associated maternal hypotension in Cesarean delivery is the most frequent and troublesome complication, posing serious risks to mothers and compromising neonatal well-being. The effective volume of intravenous crystalloid as the preventive strategy in this context has not been estimated.

METHODS

Eighty-five parturients with ASA physical status I/II undergoing elective Cesarean delivery were screened and 67 eligible women were assigned to receive pre-spinal crystalloid loading. Hyperbaric 0.5% bupivacaine 2mL (10mg) plus morphine 50μg was given to all patients. The volume of crystalloid was determined by an up-and-down sequential method. The crystalloid was infused at a rate of 100-150mL.min(-1) prior to the spinal anesthetic injection. The initial volume of crystalloid was 5mL.kg(-1). Volume-effect data were fitted to a sigmoidal maximum efficacy model and the median effective volume (EV(50)) and corresponding 95% confidence interval (95% CI) were estimated using maximum likelihood estimation and logistic regression with Firth's correction.

RESULTS

A total of 67 subjects completed the study and were analyzed. Twenty-eight (41.8%) patients developed hypotension with their systolic blood pressure (SBP) decreasing > 20% of baseline. The EV(50) of crystalloid were 12.6mL.kg(-1) (95% CI, 11.6 to 14.8mL.kg(-1)). With Firth's correction, the pooled probability of an effective preventive volume of crystalloid at 13mL.kg(-1) was 50.2% (95% CI, 30% to 83.1%).

CONCLUSIONS

The estimated EV(50) of the preloaded crystalloid required to prevent spinal anesthesia-induced hypotension in a Cesarean section is, approximately, 13mL.kg(-1). However, prophylactic or therapeutic vasoconstrictors should also be prepared and administered at an appropriate time.

Which goal for fluid therapy during colorectal surgery is followed by the best outcome: near-maximal stroke volume or zero fluid balance?

BACKGROUND

We aimed to investigate whether fluid therapy with a goal of near-maximal stroke volume (SV) guided by oesophageal Doppler (ED) monitoring result in a better outcome than that with a goal of maintaining bodyweight (BW) and zero fluid balance in patients undergoing colorectal surgery.

METHODS

In a double-blinded clinical multicentre trial, 150 patients undergoing elective colorectal surgery were randomized to receive fluid therapy after either the goal of near-maximal SV guided by ED (Doppler, D group) or the goal of zero balance and normal BW (Zero balance, Z group). Stratification for laparoscopic and open surgery was performed. The postoperative fluid therapy was similar in the two groups. The primary endpoint was postoperative complications defined and divided into subgroups by protocol. Analysis was performed by intention-to-treat. The follow-up was 30 days. The trial had 85% power to show a difference between the groups.

RESULTS

The number of patients undergoing laparoscopic or open surgery and the patient characteristics were similar between the groups. No significant differences between the groups were found for overall, major, minor, cardiopulmonary, or tissue-healing complications (P-values: 0.79; 0.62; 0.97; 0.48; and 0.48, respectively). One patient died in each group. No significant difference was found for the length of hospital stay [median (range) Z: 5.00 (1-61) vs D: 5.00 (2-41); P=0.206].

CONCLUSIONS

Goal-directed fluid therapy to near-maximal SV guided by ED adds no extra value to the fluid therapy using zero balance and normal BW in patients undergoing elective colorectal surgery.

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.

[Management of hypotension during spinal anaesthesia for elective caesarean section: a survey of practice in Lorraine region]

OBJECTIVE

The aim of the survey was to describe current practice in management of hypotension during spinal anaesthesia for elective caesarean section in Lorraine.

STUDY DESIGN

Cross-sectional study by a mail survey.

METHODS

A 20-item postal questionnaire was sent to all anaesthetists working in public or private hospital with a maternity unit in Lorraine.

RESULTS

The response rate was 65%. Fifty-one percent of the respondents did not have a written procedure for the management of spinal-induced hypotension. Fluid preloading with or without vasopressor was the most common practice. Colloids were used by 20% of the respondents. For prevention of hypotension, 37% used ephedrine, 28% used phenylephrine mostly in association with ephedrine and 9% based their choice on heart rate. Twenty-six percent did not administer any vasopressor to prevent hypotension. First choice vasopressor for treatment of hypotension was ephedrine. Anaesthetists in academic practice were more likely to use coloading and phenylephrine administration, but none of them used colloids for pre- or coloading.

CONCLUSION

Management of hypotension during spinal anaesthesia for elective caesarean section was significantly influenced by the type of practice.

A comparison of the effects of preanesthetic administration of crystalloid versus colloid on intrathecal spread of isobaric spinal anesthetics and cerebrospinal fluid movement

BACKGROUND

Movement of the cerebrospinal fluid (CSF) is one of the most important factors in determining the intrathecal spread of isobaric spinal anesthetics. Preanesthetic administration of either crystalloid or colloid immediately before spinal anesthesia (preload) may result in different CSF pulsatile movement because of their different physical properties. We examined whether preload of crystalloid versus colloid may have different effects on the intrathecal spread of isobaric spinal anesthetics as a result of their different CSF dynamics regarding its pulsatile movement.

METHODS

In a clinical study of isobaric spinal anesthesia, patients were allocated into 1 of 2 groups according to preload with either crystalloid (n = 30) or colloid (n = 30) before spinal anesthesia with 0.5 isobaric tetracaine. The pulsatile movements of CSF at the L2-3 intervertebral space and midportion of the aqueduct of Sylvius were also examined by magnetic resonance images in healthy volunteers (n = 23) at 0, 30, and 60 minutes after administering either crystalloid or colloid.

RESULTS

In the clinical study, the time to reach the peak sensory block level was delayed significantly in the crystalloid preload group (27.2 ± 17.8 minutes; P < 0.01) compared with the colloid preload group (13.9 ± 7.0 minutes). The median sensory block levels of the crystalloid preload group at 15 minutes (T10, P < 0.05) and 20 minutes (T9.5, P < 0.05) were significantly lower than those (T8, T7, respectively) of the colloid preload group. In the magnetic resonance imaging study, cranially directed CSF pulsatile movement decreased significantly at the L2-3 intervertebral intrathecal space at 30 minutes after crystalloid administration, but not after colloid administration. The CSF production rate significantly increased at 30 minutes (637 μL/min, P < 0.05) after crystalloid preload compared with the baseline measurement (448 μL/min), and then slightly decreased (609 μL/min) at 60 minutes. In the colloid preload group, the CSF production rate was not statistically significant compared with the baseline measurement (464, 512, and 542 μL/min at baseline, 30, and 60 minutes, respectively).

CONCLUSIONS

Compared with a colloid preload, which may be comparable to the no-preload condition, crystalloid preload prolonged the time to reach the peak sensory block level in isobaric spinal anesthesia, which might have been caused by a significant decrease in CSF pulsatile movement. This attenuated CSF pulsatile movement in the crystalloid preload group might have resulted from significant increases of CSF production.

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.

The effects of intravenous ephedrine during spinal anesthesia for cesarean delivery: a randomized controlled trial

We designed a randomized, double-blinded study to determine the efficacy and safety of 0.5 mg/kg intravenous ephedrine for the prevention of hypotension during spinal anesthesia for cesarean delivery. Patients were randomly allocated into two groups: ephedrine group (n=21) and control group (n=21). Intravenous preload of 15 mL/kg lactated Ringer's solution was given. Shortly after the spinal injection, ephedrine 0.5 mg/kg or saline was injected intravenous for 60 sec. The mean of highest and lowest heart rate in the ephedrine group was higher than those of control group (P<0.05). There were significant lower incidences of hypotension and nausea and vomiting in the ephedrine group compared with the control group (8 [38.1%] vs. 18 [85.7%]); (4 [19%] vs. 12 [57.1%], respectively) (P<0.05). The first rescue ephedrine time in the ephedrine group was significantly longer (14.9+/-7.1 min vs. 7.9+/-5.4 min) than that of the control group (P<0.05). Neonatal outcome were similar between the study groups. These findings suggest, the prophylactic bolus dose of 0.5 mg/kg intravenous ephedrine given at the time of intrathecal block after a crystalloid fluid preload, plus rescue boluses reduce the incidence of hypotension.

Comparison of potency of ephedrine and mephentermine for prevention of post-spinal hypotension in caesarean section

The dosages and potency of intravenous mephentermine for prevention of post-spinal hypotension are not available in English literature. This study was designed to determine the minimum effective dose (ED50) of mephentermine and to compare its potency with that of ephedrine for prevention of post-spinal hypotension in parturients undergoing caesarean section. Dixon's up-down method of sequential allocation was used for vasopressor doses. Following administration of spinal anaesthesia, patients received a prophylactic infusion with 50 mg infused over a period of 30 minutes as the initial dose and dose intervals of 5 mg, of either ephedrine or mephentermine. The ED50 of ephedrine was 25.0 mg (95% CI 15.5 to 40.4 mg). For mephentermine, the up-down method was abandoned due to the success of the minimum dose possible but the ED50 appeared to be less than 5 mg. In conclusion, the minimum effective dose of mephentermine is much less than that of ephedrine for prevention of post-spinal hypotension. Another trial with a lower starting dose and smaller dose interval of mephentermine is required to determine the potency ratio of mephentermine and ephedrine.

[Spinal anaesthesia for caesarean section: fluid loading, vasopressors and hypotension]

OBJECTIVE

To analyze the different preventive and curative strategies for the management of hypotension during spinal anaesthesia for caesarean section.

DATA SOURCES

Data related to hypotension during spinal anesthesia for caesarean section were searched in the Medline database. Trials published in English or French were reviewed.

DATA SYNTHESIS

Hypotension during caesarean section under spinal anaesthesia is very frequent (55 to 90%) if not prevented. It can induce complications for the mother and/or the fetus. Crystalloid preload alone is ineffective. Colloid preload is effective but might be better used as a second line treatment. Ephedrine has been the vasopressor of choice for long, but has a weak prophylactic efficacy. In addition, it can induce maternal cardiovascular adverse effects and fetal acidosis. Prophylactic phenylephrine, with or without ephedrine according to maternal heart rate, is at least as effective as ephedrine, with less adverse effects. Crystalloid loading at the time of spinal injection ("co-/post-loading") enhances the haemodynamic control provided by vasopressors.

CONCLUSION

Hypotension during spinal anesthesia for caesarean section must be systematically detected, prevented and treated without delay. The association of vasopressor(s) (phenylephrine with or without ephedrine) with a rapid crystalloid loading at the time of spinal injection represents the most interesting strategy nowadays.

Manual displacement of the uterus during Caesarean section

Ninety ASA 1 and 2 pregnant women with term singleton pregnancies and no maternal and fetal complications, scheduled for elective or emergency Caesarean section, were randomly allocated to group LT (15 degrees left lateral table tilt, n = 45) and group MD (leftward manual displacement, n = 45). Subarachnoid block was established with a 25-gauge spinal needle at the L3-L4 interspace using 1.5 ml of 0.5% hyperbaric bupivacaine. A median sensory level of T6 was observed in both groups but the incidence of hypotension was markedly lower in group MD when compared to group LT (4.4% vs 40%; p < 0.001) with a significant reduction in mean (SD) ephedrine requirement (6 (0) vs 11.3 (4.9) mg; p < 0.001). The mean (SD) fall in systolic blood pressure was 28.8 (7.3) mmHg in group LT and 20 (12.7) mmHg in group MD. The time to maximum fall in systolic blood pressure was similar in both groups (4.5 min). We conclude that manual displacement of the uterus effectively reduces the incidence of hypotension and ephedrine requirements when compared to 15 degrees left lateral table tilt in parturients undergoing Caesarean section.

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

BACKGROUND

The effects of colloid loading after spinal anesthesia on hemodynamics in parturients during cesarean section have not been fully understood. This study tested the hypothesis that colloid loading after spinal blockade can reduce hypotension compared with preloading, and affect neonatal outcomes.

METHODS

A prospective, randomized, double-blinded study was performed in 54 healthy parturients (ASA I or II) undergoing elective cesarean section. Patients were randomly allocated into one of three groups to receive rapid infusion of 6% hydroxyethylstarch (HES) (70 kDa/0.5) before spinal anesthesia (15 ml x kg(-1), HES preload group, n = 18), or rapid infusion of HES after induction of spinal anesthesia (15 ml x kg(-1), HES coload group, n = 18), or no rapid infusion (control, n = 18). The incidence of hypotension, and the amount of ephedrine used to treat hypotension was compared. Neonatal outcomes were also assessed by pH, base excess, lactate concentration, and Apgar scores.

RESULTS

The incidence of hypotension was significantly lower in HES preload and HES coload groups than control group (P < 0.01). Although systolic blood pressure decreased after spinal blockade in all groups, the lowest SBP after spinal blockade until delivery was significantly higher in fluid loading groups than control (P < 0.001). Similarly, total dose of ephedrine to treat hypotension was lower in fluid loading groups (P < 0.001). Umbilical cord pH, umbilical lactate concentration, and the incidence of neonates with Apgar score <7 were similar.

CONCLUSION

Colloid loading after induction of spinal anesthesia was similarly effective in reducing hypo- tension compared with preloading in cesarean section.

A randomized trial of crystalloid versus colloid solution for prevention of hypotension during spinal or low-dose combined spinal-epidural anesthesia for elective cesarean delivery

BACKGROUND

Spinal anesthesia for cesarean delivery is commonly associated with hypotension and nausea and vomiting, and preload with crystalloid or colloid solution is widely recommended. Low-dose spinal via the combined spinal-epidural technique appears to cause less hypotension and nausea and vomiting. The aim of this study was to investigate whether the combined use of colloid preload and combined spinal-epidural technique might further reduce the rates of these symptoms.

METHODS

Women undergoing elective cesarean delivery were randomly allocated to one of four groups (50 in each) to receive crystalloid preload before spinal anesthesia, colloid preload before spinal anesthesia, crystalloid preload before combined spinal-epidural anesthesia, and colloid preload before combined spinal-epidural anesthesia. The incidences of hypotension and nausea and vomiting were compared. Spinal anesthesia was performed with 0.5% hyperbaric bupivacaine 9 mg and fentanyl 20 microg, and combined spinal-epidural anesthesia with 0.5% hyperbaric bupivacaine 6 mg + fentanyl 20 microg followed by epidural injection of 0.25% bupivacaine 10 mL.

RESULTS

The frequencies of hypotension were 44%, 18%, 24%, and 20% in crystalloid preload-spinal anesthesia, colloid preload-spinal anesthesia, crystalloid preload-combined spinal epidural anesthesia, and colloid preload-combined spinal epidural anesthesia groups, respectively. The frequencies of nausea and vomiting were 20%, 2%, 8%, and 4% in respective groups.

CONCLUSION

Colloid preload and low-dose spinal anesthesia alone or in combination lowered the incidences of hypotension and nausea. However, the combination of two methods failed to demonstrate further decreases in the incidence of the symptoms compared to the colloid-spinal anesthesia or crystalloid-combined spinal-epidural anesthesia groups.

Fluid therapy for the surgical patient

Perioperative fluid therapy is the subject of much controversy, and the results of the clinical trials investigating the effect of fluid therapy on outcome of surgery seem contradictory. The aim of this chapter is to review the evidence behind current standard fluid therapy, and to critically analyse the trials examining the effect of fluid therapy on outcome of surgery. The following conclusions are reached: current standard fluid therapy is not at all evidence-based; the evaporative loss from the abdominal cavity is highly overestimated; the non-anatomical third space loss is based on flawed methodology and most probably does not exist; the fluid volume accumulated in traumatized tissue is very small; and volume preloading of neuroaxial blockade is not effective and may cause postoperative fluid overload. The trials of 'goal-directed fluid therapy' aiming at maximal stroke volume and the trials of 'restricted intravenous fluid therapy' are also critically evaluated. The difference in results may be caused by a lax attitude towards 'standard fluid therapy' in the trials of goal-directed fluid therapy, resulting in the testing of various 'standard fluid regimens' versus 'even more fluid'. Without evidence of the existence of a non-anatomical third space loss and ineffectiveness of preloading of neuroaxial blockade, 'restricted intravenous fluid therapy' is not 'restricted', but rather avoids fluid overload by replacing only the fluid actually lost during surgery. The trials of different fluid volumes administered during outpatient surgery confirm that replacement of fluid lost improves outcome. Based on current evidence, the principles of 'restricted intravenous fluid therapy' are recommended: fluid lost should be replaced and fluid overload should be avoided.

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.

Is ephedrine infusion more effective at preventing hypotension than traditional prehydration during spinal anaesthesia for caesarean section in African parturients?

BACKGROUND

Hypotension following spinal anaesthesia for caesarean section may result in maternal nausea and vomiting and decreased uteroplacental blood flow with possible fetal acidaemia. Numerous methods have been tried to minimise hypotension. In developing countries where resources are limited, this study aimed to compare a standard infusion of ephedrine with traditional prehydration to prevent spinal hypotension.

METHOD

Sixty patients for elective caesarean section were randomly allocated to group 1: 1 L 0.9% saline before spinal block, and group 2: infusion of ephedrine 30 mg in 1 L of 0.9% saline after spinal block, titrated to maternal systolic pressure. Spinal anaesthesia was achieved with 2.5 mL of 0.5% heavy bupivacaine in the L3/L4 interspace.

RESULTS

Systolic pressure decreased 5 min after spinal block. Group 2 had higher mean values of systolic pressure throughout most of the study period than group 1 (P < 0.05). Hypotension occurred in 70% of patients in group 1 and 40% of patients in group 2 (P = 0.037). Severe hypotension occurred in 40% of group 1 and 13.3% of group 2 (P = 0.039). Nausea was the most common side effect of hypotension, occurring in 39.4% of all hypotensive patients. Other complications, including hypertension, tachycardia and bradycardia were similar in the two groups. Neonatal outcome was similar in the two groups and median Apgar scores at one and five minutes were 8.

CONCLUSION

Prophylactic ephedrine given by standard infusion set was more effective than crystalloid prehydration in the prevention of hypotension during spinal anaesthesia for elective caesarean section.

Intrapartum temperature changes following the intravenous crystalloid bolus for epidural analgesia

OBJECTIVE

To assess the effect of the intravenous crystalloid bolus given before epidural analgesia on maternal temperature during labour. Multiple studies have demonstrated a hyperthermic trend in parturient women receiving epidural analgesia. This temperature rise may be affected by the pre-epidural intravenous crystalloid bolus.

METHODS

Intrapartum oral temperatures were recorded in 40 singleton parturient women immediately before and after an intravenous bolus of Ringer's lactate solution (1L at room temperature [21 degrees C]) and at one hour after standardized insertion of an epidural catheter for analgesia. Exclusion criteria included antibiotic administration, chorioamnionitis, and initial maternal temperature above 37.5 degrees C. Group means were compared using the 2-tailed paired Student t test.

RESULTS

There was no significant trend towards a decrease in maternal temperature after the crystalloid bolus (mean change -0.07 degree C, P = 0.33). Similarly, there was no initial trend towards an increased maternal temperature after epidural insertion (mean change + 0.02 degrees C, P > 0.7). Separate analyses using parity, body mass index, and bolus duration as covariates showed that these variables did not affect maternal temperature changes (P > or = 0.2).

CONCLUSION

Our study indicates that intravenous infusion of a crystalloid bolus at room temperature before induction of epidural analgesia does not significantly decrease parturient temperature.

Warm or cold saline for volume preload before spinal anaesthesia for caesarean section?

In this study, we compared the effect of prophylactic administration of warm and cold saline against spinal anaesthesia induced hypotension in parturients undergoing elective caesarean section. One hundred and thirteen parturients with singleton pregnancies received an i.v. infusion of isotonic saline 20 mL x kg(- 1)during the 15 min before spinal injection followed by 10 mL x kg(- 1)during the 20 min after spinal injection. Fifty-seven patients were allocated to the warm saline group (37 degrees C) and 56 to the cold saline group (21 degrees C). Discomfort in the infusion arm was less in the warm saline group (P<0.01), whereas the incidence of shivering was similar in the two groups. Following induction of spinal anaesthesia, blood pressures were significantly higher in the cold saline infusion group compared to the warm saline group (P<0.05). However, the group mean difference in mean arterial pressure was only about 5 mmHg, and the amount of ephedrine administered and the incidence of clinical significant hypotension did not differ between groups. In conclusion, the temperature of the fluid used for i.v. preload and maintenance at caesarean section under spinal anaesthesia is not clinically important.

Randomised trial of intravenous infusion of ephedrine or mephentermine for management of hypotension during spinal anaesthesia for Caesarean section

This study compared the effects of intravenous infusions of ephedrine and mephentermine for maintenance of maternal arterial pressure and neonatal outcome in pregnant women receiving subarachnoid block for lower segment Caesarean section. Sixty patients who developed hypotension following subarachnoid block for Caesarean section were randomly divided into two groups of 30 each to receive an intravenous infusion of ephedrine or mephentermine. Hypotension was defined as a decrease in systolic blood pressure of > or = 20% from the baseline value or an absolute value of <100 mmHg, whichever was higher. The vasopressor infusion was titrated to maintain systolic blood pressure between 'hypotension' and baseline values. Baseline haemodynamic parameters, haemodynamic changes subsequent to the start of vasopressor infusion, duration of hypotension and amount of vasopressor required were statistically similar for both groups. Neonatal APGAR scores and acid-base profiles were also comparable. To conclude, mephentermine can be used as safely and effectively as ephedrine for the management of hypotension during spinal anaesthesia in patients undergoing elective Caesarean section.

Reverse pressure softening: a simple tool to prepare areola for easier latching during engorgement

Successful breastfeeding requires efficient milk transfer through the nipple-areolar complex, which includes subareolar tissue. Subareolar tissue resistance increases during engorgement, when expanded circulation and excess interstitial fluid compete for space with increasing milk volumes. Physiologic and iatrogenic events often combine to produce distortion of breast anatomy. Resulting latch difficulty, delayed milk ejection reflex, poor milk transfer, pain, and nipple damage discourage many mothers. The rationale and technique for a simple intervention developed in practice are described: reverse pressure softening (RPS) before latching significantly reduces resistance of subareolar tissue, temporarily freeing it to interact more efficiently with the baby's mouth. RPS also triggers the milk ejection reflex promptly. The health care provider can perform RPS or teach the mother and her significant others, even by telephone.

Sequential compression device with thigh-high sleeves supports mean arterial pressure during Caesarean section under spinal anaesthesia

BACKGROUND

This study investigated the use of a Sequential Compression Device (SCD) with thigh-high sleeves and a preset pressure of 50 mm Hg that recruits blood from the lower limbs intermittently, as a method to prevent spinal hypotension during elective Caesarean section. Possible association of arterial pressure changes with maternal, fetal, haemodynamic, and anaesthetic factors were studied.

METHODS

Fifty healthy parturients undergoing elective Caesarean section under spinal anaesthesia were randomly assigned to either SCD (n=25) or control (n=25) groups. A standardized protocol for pre-hydration and anaesthetic technique was followed. Hypotension was defined as a decrease in any mean arterial pressure (MAP) measurement by more than 20% of the baseline MAP. Systolic (SAP), MAP and diastolic (DAP) arterial pressure, pulse pressure (PP), and heart rate (HR) were noted at baseline and every minute after the spinal block until delivery.

RESULTS

A greater than 20% decrease in MAP occurred in 52% of patients in the SCD group vs 92% in the control group (P=0.004, odds ratio 0.094, 95% CI 0.018-0.488). There were no significant differences in SAP, DAP, HR, and PP between the groups.

CONCLUSION

SCD use in conjunction with vasopressor significantly reduced the incidence of a 20% reduction of MAP.

Spinal anaesthesia for obstetrics

For a long time, epidural anaesthesia has been considered the method of choice for Caesarean delivery. The increased incidence of hypotension by the rapid onset of sympathetic blockade under spinal anaesthesia has been associated with a decline in uteroplacental blood flow and significant fetal acidosis, which may compromise neonatal well-being. Nevertheless, a decrease in fetal pH has not been shown to reduce neonatal Apgar or neurobehavioural assessment scores. Maternal blood pressure can be preserved with little side effects with low doses of vasopressors. On the other hand, spinal anaesthesia conveys significant advantages over epidural anaesthesia such as the simplicity of its use and the speed of onset, which allows neuraxial anaesthesia in urgent Caesarean sections and thus reduces the necessity for general anaesthesia. The small doses of local anaesthetics required to perform spinal anaesthesia reduce the risks of systemic toxicity to zero. Spinal anaesthesia is now considered the method of choice for urgent Caesarean section. The use of intrathecal opioids has profoundly changed the quality of spinal anaesthesia, with improved analgesia, a reduction in local anaesthetic requirements and shorter duration of motor blockade. Preliminary studies indicate that spinal anaesthesia may be safely performed in patients with severe pre-eclampsia, in whom spinal anaesthesia was previously considered contraindicated.

Complications of neuraxial blockade

Epidural and spinal anesthesia enjoy wide usage in modern practice, and each can provide reliable and safe anesthesia. Although the techniques appear to the casual observer to require relatively straightforward technical skill, both are fraught with myriad hazards and potential complications. It is the familiarity with and the understanding of these complications that makes for safe and professional practice of these techniques.

Frequency of hypotension and bradycardia during general anesthesia, epidural anesthesia, or integrated epidural-general anesthesia for total hip replacement

STUDY OBJECTIVE

To evaluate the frequency of hypotension and bradycardia during integrated epidural-general anesthesia as compared with general anesthesia or epidural anesthesia alone.

DESIGN

Prospective, randomized, open, multicenter study.

SETTING

Inpatient anesthesia at 7 University or Hospital Departments of anesthesia.

PATIENTS

210 ASA physical status I, II, and III patients undergoing elective total hip replacement.

INTERVENTIONS

Using a balanced randomization method, each hospital enrolled 30 consecutive patients who received integrated epidural-general anesthesia, epidural anesthesia, or general anesthesia.

MEASUREMENTS AND MAIN RESULTS

Occurrence of clinically relevant hypotension (systolic arterial blood pressure (BP) decrease >30% from baseline), or bradycardia (heart rate (HR) <45 bpm) requiring pharmacologic treatment were recorded, as well as routine cardiovascular parameters. Clinically relevant hypotension during induction of nerve block was reported in 13 patients receiving epidural block (18%) and 16 patients receiving epidural-general anesthesia (22%) (p = 0.67). Subsequently, 22 of the remaining 54 patients in the epidural-general anesthesia group (41%) developed hypotension after the induction of general anesthesia, as compared with 16 patients of the general anesthesia group (23%) (p = 0.049). No differences in HR or in frequency of bradycardia were observed in the three groups.

CONCLUSIONS

The induction of general anesthesia in patients with an epidural block up to T10 increased the odds of developing clinically relevant hypotension as compared with those patients who received no epidural block, and was associated with a twofold increase of the odds of hypotension as compared with the use of epidural anesthesia alone.

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

BACKGROUND

Maternal hypotension is the most frequent complication of spinal anaesthesia for caesarean section. Most workers define hypotension as a maternal systolic blood pressure below 70-80% of baseline recordings and/or an absolute value of < 90 - 100mmHg. Hypotension is often associated with nausea and vomiting and, if severe, poses serious risks to mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis and neurological injury). Several strategies are currently used to prevent or minimise hypotension but there is no established ideal technique.

OBJECTIVES

To assess the relative efficacy and side effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Trials Register (January 2002) and the Cochrane Controlled Trials Register (Cochrane Library, Issue 4, 2001).

SELECTION CRITERIA

All published or unpublished 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

Trials identified from searching are assessed for inclusion by the same two reviewers independently. Studies are excluded from review where: hypotension is not an outcome measure or clearly defined prior to administering a rescue treatment; randomisation is unsatisfactory; the spinal anaesthetic technique or dose of local anaesthetic is not controlled-for; and the intervention is implemented in response to a fall in blood pressure rather than for prevention. Review Manager software is used for calculation of the treatment effect, represented by relative risks and proportional and absolute risk reductions.

MAIN RESULTS

Twenty-five trials (1477 women) meet our inclusion criteria. Four of fifteen interventions reviewed reduce the incidence of hypotension under spinal anaesthesia for caesarean section: (1) crystalloid versus control, relative risk (RR) 0.78 (95% confidence interval (CI) 0.63, 0.98); (2) pre-emptive colloid administration versus crystalloid, RR 0.54 (95% CI 0.37, 0.78); (3) ephedrine versus control, RR 0.69 (95% CI 0.57, 0.84); and (4) lower limb compression versus control, RR 0.70 (95% CI 0.59, 0.83). Ephedrine is associated with dose-related maternal hypertension and tachycardia, and fetal acidosis of uncertain clinical significance.

REVIEWER'S CONCLUSIONS

No intervention reliably prevents hypotension during spinal anaesthesia for caesarean section. No conclusions are drawn regarding rare adverse effects of interventions due to their probable low incidence and the small numbers of women studied. Further trials are recommended, in particular assessing a combination of the beneficial interventions, ie colloid or crystalloid preloading, ephedrine administration and leg compression with bandages, stockings or inflatable boots.