Ondansetron preloading with crystalloid infusion reduces maternal hypotension during cesarean delivery

Ondansetron Reduces the Incidence of Hypotension after Spinal Anaesthesia: A Systematic Review and Meta-Analysis

Hypotension induced by spinal anaesthesia is a common clinical complication associated with multiple perioperative adverse events. We conducted a systemic review and meta-analysis to confirm whether ondansetron could alleviate hypotension following spinal anaesthesia. PubMed, Embase, Web of Science, and Cochrane Library were searched to identify eligible randomised controlled trials from their respective database inception dates to 30 September 2022. The primary outcome of the meta-analysis was the incidence of hypotension after spinal anaesthesia. The risk of bias in the included studies was evaluated using the revised Cochrane risk of bias tool for randomised trials (RoB 2.0). Grading of Recommendations, Assessment, Development, and Evaluation was applied to assess the level of certainty. A total of 25 studies were included in this research. The meta-analysis revealed that ondansetron significantly decreased the incidence of hypotension (RR = 0.65, 95% CI 0.53−0.80, p < 0.01, I2 = 64%) and bradycardia. In addition, patients treated with ondansetron had a reduced need for vasopressors administration. This study suggests that ondansetron may be recommended as a prophylaxis for hypotension and bradycardia following spinal anaesthesia; the level of evidence was moderate with a high level of heterogeneity.

Efficacy of Variable Doses of Prophylactic Intravenous Ondansetron in Attenuating Spinal Induced Hypotension in Parturients Undergoing Caesarean Delivery: A Randomised Control Trial

Introduction

Spinal anaesthesia is frequently associated with adverse effects like maternal hypotension and bradycardia. This effect is due to a decrease in systemic vascular resistance, a decrease in central venous pressure or Bezold-Jarisch Reflex (mediated by 5-HT3 receptors). We aimed to measure the effect of three different doses of prophylactic intravenous ondansetron (5-HT3 antagonists) with a placebo on maternal haemodynamics.

Methods

A prospective randomised control study was done over 240 parturients, aged 19-35 years. They were randomly allocated into four groups (n=60) Group O4, Group O6, Group O8 and Group S to receive either intravenous ondansetron 4 mg, 6 mg, 8 mg or 0.9% normal saline respectively. Haemodynamic variables (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP], heart rate [HR]) were recorded at 2-minute intervals for the first 20 minutes and at 5-minute intervals for further 30 minutes.

Results

A significant decrease in haemodynamic parameters was observed in group S when compared with ondansetron groups at various time intervals (p<0.05). The difference was most significant in groups O6 and O8. Development of nausea and vomiting was significantly higher in Group S compared to ondansetron groups (p< 0.005). The requirement for ephedrine was more in Group S in comparison to ondansetron groups (p<0.0001).

Conclusion

All three groups of ondansetron showed a decrease in the incidence of hypotension and use of vasopressor but Group O6 and O8 were more effective in attenuating spinal-induced hypotension in parturients undergoing caesarean section.

Comparison between mephentermine and ondansetron for the prevention of post spinal hypotension: a prospective randomized trial

Background and Aims: Spinal anesthesia is a technique often associated with side effects like hypotension and bradycardia. Recent studies have shown that the use of ondansetron leads to a decreased incidence of hypotension induced by spinal anesthesia. This prospective, randomized, controlled, double-blind study was done to compare the efficacy of the prophylactic use of intravenous (IV) ondansetron and mephentermine on post-spinal hypotension. Methods: A total of 130 patients were randomly allocated to one of two groups: Group O received 4 mg IV ondansetron and Group M received 6 mg of IV mephentermine. All patients received spinal anesthesia using 3 mL of 0.5% hyperbaric bupivacaine. Assessment of blood pressure and heart rate (HR) was done for 30 minutes after spinal anesthesia was performed. Quantitative data were analyzed using ANOVA tests and qualitative data were analyzed using the Chi-square tests. Results: Both groups were comparable regarding demographic data. Mean arterial blood pressure (MAP) in Group O was lower than Group M at 5 to 25 minutes and difference of MAP between the two groups was > 20% of baseline values (p < 0.05). HR was comparable between groups. No statistically significant differences were seen in side effects between the two groups. Conclusion: Our study shows that the preemptive use of both ondansetron and mephentermine significantly decreases the incidence of post-spinal hypotension.

The effect of ondansetron administration 20 minutes prior to spinal anaesthesia on haemodynamic status in patients undergoing elective caesarean section: A comparison between two different doses

Background and Aims

Spinal anaesthesia is currently the most common method used for managing patients undergoing elective caesarean sections. Recent meta-analyses have been supporting the use of 5-HT3 antagonists, like ondansetron, to attenuate hypotension induced by spinal block. Various doses of ondansetron were given intravenously five minutes before spinal block. However, a consensus on definitive dose and timing for maximal benefit is yet to be agreed upon.

Methods

Our prospective randomised clinical trial investigated a new approach by administrating intravenous ondansetron 20 minutes before spinal anaesthesia. This work investigated ondansetron effect on both haemodynamic changes and vasopressors use by dividing patients into three groups. The first group O4 (n = 51) received 4 mg ondansetron, the second group O6 (n = 51) received 6 mg ondansetron, and the control group C (n = 50) received normal saline. We recorded systolic blood pressure (SBP), diastolic blood pressure (DBP) and the mean blood pressure (MBP) at different time intervals.

Results

There was no significant difference in blood pressure measurements among the study groups (P > 0.05). The consumption of ephedrine in the control group is higher than both of the ondansetron groups (P > 0.001), with a mean dose of 27.2 ± 20.5 mg of ephedrine for group C, compared to 17.8 ± 14.9 and 14.7 ± 11.3 in O4 and O6 groups, respectively. Episodes of hypotension and number of patients with hypotension were not significantly different among the studied groups (P = 0.07; P = 0.96, respectively).

Conclusions

Prophylactic 4 and 6 mg ondansetron given 20 minutes before spinal anaesthesia in caesarean section does not reduce the incidence of hypotension.

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.

Effect of Intravenous Ondansetron on Spinal Anesthesia-Induced Hypotension and Bradycardia: A Randomized Controlled Double-Blinded Study

Background:

Spinal anesthesia is a safe anesthetic technique commonly practiced. However, it is associated with hypotension (33%), bradycardia (13%), and shivering which are induced by hypovolemia, sympathetic blockade, and Bezold–Jarisch reflex through intracardiac serotonin (5HT3) receptors and vagus nerve.

Aim:

To study the effect of intravenous (i.v.) ondansetron on hypotension and bradycardia induced by spinal anesthesia.

Setting and Design:

This was a randomized controlled double-blinded study done in a tertiary care teaching hospital.

Methods:

Of 140 patients, 70 in Group A received 2 mL of i.v. ondansetron 4 mg and 70 in the Group B received 2 mL of i.v. normal saline. 3 mL of 0.5% hyperbaric bupivacaine was injected intrathecally. Measurements of blood pressure and heart rate (HR) were taken every 3 min for 30 min after spinal anesthesia was performed. Mean arterial pressure (MAP) drop more than 20% was considered as incidence of hypotension and ephedrine 6 mg i.v. was given. HR drop >20% was regarded as bradycardia and atropine 0.5 mg i.v. was given.

Statistical Tests:

Quantitative data were analyzed using ANOVA test and qualitative data were analyzed using Chi-square test.

Results:

Both groups are comparable in demographic data. Four (5.7%) patients in Group B and no patients in Group A had incidence of bradycardia and atropine requirement (P = 0.120). There was no statistically significant difference in systolic blood pressure, diastolic blood pressure, and MAP. 19 (27%) patients in Group A and 33 (47.1%) in Group B required ephedrine with P = 0.029. 12 (17.1%) in Group B and no patients in Group A had shivering with P = 0.0001.

Conclusion:

Our study indicates that prophylactic use of ondansetron before spinal anesthesia significantly reduces the requirement of ephedrine and shivering.

Does prophylactic ondansetron reduce norepinephrine consumption in patients undergoing cesarean section with spinal anesthesia?

PURPOSE

Spinal anesthesia-induced hypotension (SAIH) during cesarean delivery is not rare and frequently leads to materno-fetal discrepancy and collapse. More recently, norepinephrine has been proposed for the prevention and treatment of SAIH with fewer tendencies to decrease heart rate and cardiac output. Ondansetron has been reported to reduce the incidence of SAIH in patients undergoing cesarean section. The aim of the present study was to assess the effect of prophylactic ondansetron on the incidence of SAIH, norepinephrine consumption, and adverse effects.

METHODS

We recruited 108 parturients with uncomplicated pregnancies undergoing elective cesarean delivery under spinal anesthesia. The parturients were divided into two groups randomly. The first group (n = 54) received 8 mg ondansetron IV (group O) and the second group (n = 54) received the same volume (4 ml) of saline (group S), 5 min before spinal anesthesia. The incidence of hypotension, cumulative episodes of hypotension, total norepinephrine consumption, and adverse effects were recorded.

RESULTS

There was no significant difference between the two groups in demographic data, parturient characteristics, and duration of surgery. No significant difference was found in the incidence of hypotension in the saline and ondansetron groups (p = 0.767). However, the cumulative episodes of hypotension and norepinephrine consumptions were significantly greater in group S than in group O (p = 0.009) (p = 0.009). There was also no significant difference in the incidence of adverse effects between the two groups.

CONCLUSION

Eight milligrams of intravenous ondansetron given 5 min before spinal anesthesia attenuated but did not prevent spinal anesthesia-induced hypotension in parturients undergoing elective cesarean delivery.

Efficacy of ondansetron for spinal anesthesia during cesarean section: a meta-analysis of randomized trials

Objective To investigate the efficacy and safety of ondansetron during cesarean section under spinal anesthesia. Methods We sought randomized controlled trials (RCTs) on ondansetron during spinal anesthesia for cesarean section in The Cochrane Library, PubMed, MEDLINE, and Web of Science from their inception to September 2016. Results Altogether, 21 RCTs were included in this study. Meta-analysis showed that the ondansetron group had a lower incidence of nausea/vomiting and bradycardia than the placebo group during cesarean section under spinal anesthesia [relative risk (RR) = 0.43, 95% confidence interval (CI) (0.36, 0.51) and RR = 0.45, 95% CI (0.26, 0.80), respectively]. There were no significant differences in the incidences of pruritus, hypotension, or shivering during cesarean section under spinal anesthesia [RR = 0.92, 95% CI (0.83, 1.02); RR = 0.72 (0.50, 1.06), 95% CI (0.50, 1.06); and RR = 0.89, 95% CI (0.71, 1.11), respectively]. Conclusion Ondansetron effectively reduces the incidences of nausea/vomiting and bradycardia under spinal anesthesia during 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 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.

Does Ondansetron Modify Sympathectomy Due to Subarachnoid Anesthesia?: Meta-analysis, Meta-regression, and Trial Sequential Analysis

BACKGROUND

Disagreement among many underpowered studies has led to an equivocal understanding of the efficacy of the 5-HT3 antagonist ondansetron in preventing the consequences of sympathectomy after subarachnoid anesthesia. The authors assessed the efficacy of ondansetron with respect to the overall quality and statistical power of the meta-analyses.

METHODS

The authors used a standard and a newer method of meta-analysis, trial sequential analysis (TSA), to estimate adjusted CIs based on how much information has been accrued. They also used random-effects meta-analyses techniques, small trial bias assessment, selection models, sensitivity analyses, and the Grading of Recommendations on Assessment, Development, and Evaluation system. These results from the aforementioned techniques were compared, and importance of consideration of these factors was discussed.

RESULTS

Fourteen randomized placebo-controlled trials (1,045 subjects) were identified and analyzed. By using conventional meta-analyses, the authors determined that ondansetron was associated with reduction in the incidence of hypotension (relative risk = 0.62 [95% CI, 0.46 to 0.83], P = 0.001; TSA-adjusted CI, 0.34 to 1.12; I = 60%, P = 0.002) and bradycardia (relative risk = 0.44 [95% CI, 0.26 to 0.73], P = 0.001; TSA-adjusted CI, 0.05 to 3.85; I = 0%, P = 0.84). However, the authors found indications of bias among these trials. TSAs demonstrated that the meta-analysis lacked adequate information size and did not achieve statistical significance when adjusted for sparse data and repetitive testing. The Grading of Recommendations on Assessment, Development, and Evaluation system showed that the results had low to very low quality of evidence.

CONCLUSIONS

The analyses fail to confirm evidence that ondansetron reduces the incidence of hypotension and bradycardia after subarachnoid anesthesia due to the risk of bias and information sizes less than the required. As results from meta-analysis are given significant weight, it is important to carefully evaluate the quality of the evidence that is input.

Effects of Preoperative Serotonin-Receptor-Antagonist Administration in Spinal Anesthesia-Induced Hypotension: A Randomized, Double-blind Comparison Study of Ramosetron and Ondansetron

BACKGROUND AND OBJECTIVES

The adverse effects of spinal anesthesia (SA) include arterial hypotension and bradycardia. The aim of this study was to compare the effects of 2 type 3 serotonin receptor antagonists in SA-induced adverse effects. Specifically, we assessed whether ramosetron was more effective than ondansetron in reducing SA-induced decreases in blood pressure (BP) and heart rate (HR).

METHODS

A total of 117 patients undergoing orthopedic surgery and receiving SA were intravenously administered 0.3 mg of ramosetron (n = 39, group R), 4 mg of ondansetron (n = 39, group O4), or 8 mg of ondansetron (n = 39, group O8). Systolic BP (SBP), diastolic BP (DBP), mean BP (MBP), HR, and the lowest SBP, DBP, MBP, and HR values were measured preoperatively (baseline) and intraoperatively. The incidence of postoperative nausea and vomiting, the need for rescue antiemetics, the amount of patient-controlled analgesia consumption, and pain score in the first 48 hours after surgery were determined.

RESULTS

Baseline values did not significantly differ among the 3 groups. After SA, SBP, DBP, MBP, and HR were lower than their baseline values in all 3 groups. The differences between the baseline and the lowest values were significantly less in group R than in groups O4 and O8 with respect to SBP (P < 0.001), DBP (P = 0.001), and MBP (P < 0.001) less in group R than in group O4 with respect to HR (P = 0.032). Intergroup differences were not significant for postoperative nausea and vomiting, the need for rescue antiemetics, patient-controlled analgesia consumption, or pain score.

CONCLUSIONS

The administration of ramosetron (0.3 mg) significantly attenuated the SA-induced decrease in BP compared with 4 or 8 mg of ondansetron and HR compared with 4 mg of ondansetron.

Ephedrine versus ondansetron in the prevention of hypotension during cesarean delivery: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Maternal hypotension is common after spinal anesthesia for cesarean delivery. We compared the effects of prophylactic ephedrine with ondansetron on post-spinal blood pressure.

METHODS

One hundred and sixty-eight term, singleton parturients were enrolled in this prospective, double-blind, placebo-controlled trial. Patients were randomized to receive either prophylactic intravenous ephedrine 10mg (Group E), ondansetron 8mg (Group O) or normal saline (Group P) immediately after spinal anesthesia. The primary outcome was maternal blood pressure between spinal block and delivery; secondary outcomes were nausea and vomiting scores, Apgar scores, numbers requiring intraoperative vasoconstrictors and the dose of vasoconstrictors required.

RESULTS

Fifty-six patients were recruited to each group, but two in Group P were excluded from the analysis owing to protocol violations. There were no significant differences between the groups in maternal systolic, diastolic or mean arterial pressures, or the proportion of patients experiencing hypotension. The proportion of patients in Group E requiring intraoperative ephedrine or any vasoconstrictor (ephedrine and/or norepinephrine) was significantly lower than that in Group P (P=0.023 and 0.034, respectively). The proportion of patients in Group O requiring intraoperative norepinephrine was significantly lower than that in Group P (P=0.02). There was no difference in the proportions of patients in Groups E and O requiring any vasoconstrictors (P=0.34).

CONCLUSIONS

There was no significant difference in maternal blood pressure in women administered prophylactic ephedrine or ondansetron after spinal anesthesia for cesarean delivery compared with placebo. Ephedrine reduced the proportion of patients requiring a rescue vasoconstrictor before delivery.