|Year : 2019 | Volume
| Issue : 3 | Page : 635-642
Effects of prophylactic dose of ondansetron on hemodynamics during spinal anesthesia in cesarean section
Al Zahraa A Abbas, Amira M Nassar, Sawsan G Mohamed
Department of Anesthesia, Intensive Care and Pain Management, Faculty of Medicine for Girls, Al Azhar University, Cairo, Egypt
|Date of Submission||24-Sep-2019|
|Date of Decision||24-Sep-2019|
|Date of Acceptance||14-Oct-2019|
|Date of Web Publication||10-Feb-2020|
Al Zahraa A Abbas
Department of Anesthesia, Intensive Care and Pain Management, Faculty of Medicine for Girls, Al Azhar University, Cairo
Source of Support: None, Conflict of Interest: None
Objective This study evaluated the efficacy of ondansetron during spinal anesthesia for cesarean section in overcoming the associated bradycardia and hypotension as the primary outcome and nausea, vomiting, intraoperative blood loss, and vasopressor requirements as the secondary outcomes.
Patients and methods A total of 60 parturient women aged 20–40 years, with American Society of Anesthesiologists status I and II, scheduled for elective cesarean section under spinal anesthesia were divided into two equal groups in a randomized-controlled fashion. Before induction of spinal anesthesia, group I (n=30) received intravenous ondansetron 4 mg and group II (n=30) received normal saline. Hemodynamic variables, such as heart rate (beat/min), systolic blood pressure, diastolic blood pressure, mean arterial blood pressure (mmHg), nausea, vomiting, intraoperative blood loss (ml), and vasopressor requirements (mg), were recorded for each parturient woman.
Results Blood pressure and heart rate were significantly decreased in group II in comparison with group I. Parturient in group I had significantly less requirement for vasopressor and had significantly lower incidences of nausea and vomiting.
Conclusion In parturient women undergoing elective cesarean section, intravenous 4-mg ondansetron significantly decreased the hypotension, bradycardia, and vasopressor doses used.
Keywords: cesarean section, ondansetron, spinal anesthesia
|How to cite this article:|
Abbas AA, Nassar AM, Mohamed SG. Effects of prophylactic dose of ondansetron on hemodynamics during spinal anesthesia in cesarean section. Sci J Al-Azhar Med Fac Girls 2019;3:635-42
|How to cite this URL:|
Abbas AA, Nassar AM, Mohamed SG. Effects of prophylactic dose of ondansetron on hemodynamics during spinal anesthesia in cesarean section. Sci J Al-Azhar Med Fac Girls [serial online] 2019 [cited 2020 Oct 24];3:635-42. Available from: http://www.sjamf.eg.net/text.asp?2019/3/3/635/278041
| Introduction|| |
Anesthetists prefer spinal anesthesia for women who will undergo cesarean section owing to many advantages like avoiding risks of general anesthesia, for better postoperative pain relief, and also for keeping the woman awake to see her baby just after birth. In addition, spinal anesthesia is a simple technique with low failure rate, rapid onset, and low drug dose . However, it frequently produces hypotension and bradycardia. Maternal hypotension is one of the most important causes of intraoperative nausea and vomiting and may also be associated with dizziness and in severe cases unconsciousness and placental hypoperfusion with fetal hypoxia and acidosis . Spinal anesthesia induces sympathetic block that leads to vasodilatation, pooling of venous blood, decrease of venous return, and low ventricular volume state, which leads to stimulation of chemoreceptors and mechanoreceptors in the cardiac wall with abrupt withdrawal of sympathetic supply, and unopposed vagal tone to the heart, which leads to bradycardia and hypotension; this reflex is called the Bezold–Jarisch reflex, and it is triggered by serotonin (5-HT3) released from thrombocytes under low ventricular volume conditions that stimulate cardiac chemoreceptors and increase the vagal tone . Serotonin (5-HT3) antagonists are suggested to be used in the prevention of hypotension and bradycardia caused by Bezold–Jarisch reflex in response to spinal anesthesia . Ondansetron is a selective 5-HT3-receptor antagonist that blocks serotonin, both centrally in the chemoreceptor trigger zone and peripherally on vagal nerve terminals (it prevents the binding of serotonin released from intestinal enterochromaffin cells to 5-HT3 receptors on adjacent vagal afferent nerves. This blockade of 5-HT3 receptors reduces nausea and vomiting by decreasing vagus nerve signaling and the subsequent release of serotonin in the brain stem) . It is used to prevent nausea and vomiting caused by chemotherapy, radiotherapy, and surgery. In light of its antagonistic effect on the 5-HT3 receptor, it may be alternative agents in attenuating spinal-induced hypotension and bradycardia . It has adverse effects including diarrhea, constipation, and headache. Serious adverse effects include QT prolongation and severe allergic reaction .
| Patients and methods|| |
This prospective randomized-controlled study was conducted at Al-Zahraa University Hospital on 60 pregnant women scheduled for elective cesarean delivery at term under spinal anesthesia that started from October 2018 to February 2019. After approval by local ethical committee of Al Azhar University and written informed consent was taken, parturient women aged between 20 and 40 years, with American Society of Anesthesiologists (ASA) class I and II (as inclusion criteria), were enrolled in this study. Exclusion criteria included contraindication for spinal anesthesia (history of allergic reaction to local anesthetic, bleeding disorders, aspirin ingestion in the preceding week, mental diseases, preexisting neurological or spinal diseases, infection at the site of injection, and unstable hemodynamics), hypertensive and hypotensive disorders with pregnancy, history of nausea and/or vomiting during the 24 h before induction of anesthesia, parturient receiving selective serotonin reuptake inhibitor or migraine medication, and hypersensitivity to ondansetron. Parturient women were randomly allocated into two equal groups (30 parturient in each group): group I was ondansetron group (N=30 parturient), which received 4-mg ondansetron in 10-ml saline intravenously 5 min before spinal puncture, and group II was the control group (N=30 parturient), which received 10 ml of saline in the same way and at the same timing, and all parturient women received 500-ml Ringer’s solution that was given over 30 min before spinal anesthesia. All parturient women were checked 24 h before surgery to fulfill the inclusion and exclusion criteria of the study through history taking, clinical examination, and for reviewing results of routine investigations including complete blood picture, coagulation profile, and by assessment of ASA physical status of the parturient. On arrival to the operating theater, peripheral intravenous line was secured with 18 G intravenous cannula, and monitoring devices including ECG, noninvasive arterial blood pressure, and pulse oximetry were connected to the parturient women. The spinal anesthesia was performed with the parturient woman in the sitting position after sterilization at L3–L4 or L4–L5 with 2–2.5-ml hyperbaric bupivacaine (10–12.5 mg/ml), which was administered after confirmation of cerebrospinal fluid free flow without barbotage through a 25-G spinal needle injection, rate of injection through 15 s. The parturient woman was immediately placed in the supine position with 15° left tilt, and the sensory block was assessed according to loss of pinprick sensation. Supplemental oxygen was administered through a nasal cannula at 4 l/min. BP, heart rate (HR), and oxygen saturation (SpO2) were recorded at the baseline before spinal anesthesia, and then after 3 min and then every 10 min until the end of the surgery. The surgeon was allowed to start surgery when the sensory block level was established at T6.
The following variables were recorded in both groups:
- Hemodynamic measurements: HR (beat/min), systolic blood pressure (SBP) (mmHg), diastolic blood pressure (DBP) (mmHg), mean arterial blood pressure (MAP) (mmHg), and SpO2% were recorded before spinal anesthesia administration, 3 min after spinal anesthesia, and at 10-min intervals until the end of surgery.
- Nausea and vomiting.
- Dose of vasopressor used (ephedrine).
- Intraoperative blood loss and volume of blood transfused.
Sample size justification
MedCalc version 126.96.36.199 program (Ostend, Belgium) was used for calculations of sample size, with statistical calculator based on 95% confidence interval and power of the study 80% with α error 5%. According to a previous study, Shabana et al.  showed that the decreases in BP and HR were significantly higher in group II in comparison with group I. Parturient women in group I had significantly less requirement for vasopressor (P=0.005), needed lower dose of vasopressor (P=0.01), and had significantly lower incidences of nausea and vomiting (P=0.03). So it can be relied upon in this study. Based on this assumption, sample size was calculated according to these values and showed that a minimal sample size of 57 cases was enough to find such a difference. Assuming a drop-out ratio of 5%, the sample size was increased to 30 cases each in two groups.
Recorded data were analyzed using the statistical package for social sciences, version 20.0 (SPSS Inc., Chicago, Illinois, USA). Quantitative data were expressed as mean±SD. Qualitative data were expressed as frequency and percentage. The following tests were done: independent samples t test of significance was used when comparing between two means, χ2 test of significance was used to compare proportions between qualitative parameters, the confidence interval was set to 95%, and the margin of error accepted was set to 5%. So, the P value was considered significant as follows: P value less than 0.05 was considered significant, P value less than 0.001 was considered as highly significant, and P value more than 0.05 was considered insignificant.
| Results|| |
The variables in demographic data did not show a statistically significant difference between the two groups with respect to age, weight, height, and ASA, as shown in [Table 1].
Regarding HR (beat/min), before spinal anesthesia, there was no statistically significant difference between the two groups (P>0.05), but in all the subsequent recordings, HR values were significant higher in group I when compared with group II (P<0.05), except in 60 min, where there was no statistically significant difference between the two groups (P>0.05) ([Table 2] and [Figure 1]).
|Table 2 Comparison between the two groups according to heart rate (beat/min)|
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|Figure 1 Comparison between the two groups according to HR (beat/min). HR, heart rate.|
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Regarding SBP, before spinal anesthesia, there was no statistically significant difference between the two groups (P>0.05), but in all the subsequent readings, SBP values were significant higher in group I when compared with group II (P<0.05), except in 60 min, where there was no statistically significant difference between the two groups (P>0.05) ([Table 3] and [Figure 2]).
|Figure 2 Comparison between the two groups according to SBP. SBP, systolic blood pressure.|
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Regarding DBP, before spinal anesthesia, there was no statistically significant difference between the two groups (P>0.05), but in all the subsequent readings, DBP values were significant higher in group I when compared with group II (P<0.05), except in 60 min, where there was no statistically significant difference between the two groups (P>0.05) ([Table 4] and [Figure 3]).
|Figure 3 Comparison between the two groups according to DBP. DBP, diastolic blood pressure.|
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Regarding MAP, before spinal anesthesia, there was no statistically significant difference between the two groups (P>0.05), but in all the subsequent readings, MAP values were significant higher in group I when compared with group II (P<0.05), except in 60 min, where there was no statistically significant difference between the two groups (P>0.05) ([Table 5] and [Figure 4]).
|Figure 4 Comparison between the two groups according to MAP. MAP, mean arterial blood pressure.|
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Regarding SpO2, there was no statistically significant difference between group I and group II in all time of the operation (P>0.05) ([Figure 5]).
|Figure 5 Comparison between the two groups according to SpO2 (%). SpO2, oxygen saturation.|
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Regarding nausea and vomiting, the incidence of nausea and vomiting was the highest in group II in comparison with that in the group I (P<0.05) ([Table 6]).
|Table 6 Comparison between the two groups according to nausea and vomiting|
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Regarding the number of parturient women who needed vasopressor, there was a statistically significant difference between the two groups. The need for vasopressor was significantly lower in group I than in group II (4 vs. 26 parturient, respectively). Regarding the dose of vasopressor, there was a significant increase in group II (dose range, 10–30 mg) in comparison with group I (dose range, 7.5–12.5 mg) (P<0.05) ([Table 7]).
|Table 7 Comparison between the two groups according to use of vasopressor|
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Regarding intraoperative blood loss, there was no statistically significant difference between the two groups (P>0.05) ([Table 8]).
|Table 8 Comparison between the two groups according to intraoperative blood loss (ml)|
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| Discussion|| |
The current study was designed to show the effect of ondansetron during spinal anesthesia for cesarean section on hemodynamic (BP and HR), nausea, vomiting as well as the doses of ephedrine required. Regarding hemodynamic measurements, the results of the current study showed that there was no statistically significant difference between the two groups in the baseline values of HR, SBP, DBP, and MAP, but in all the subsequent recordings of HR, SBP, DBP, and MAP, the values were significantly high in ondansetron group when compared with the control group, which indicated that the prophylactic bolus intravenous ondansetron caused hemodynamic stability and attenuated the postspinal hypotension and bradycardia. In agreement with the results of the current study, Ahmed and Haidy  in their study on 120 parturient scheduled for elective cesarean delivery under spinal anesthesia found that the prophylactic bolus intravenous ondansetron 4 mg could decrease the fall in MAP of parturient women following spinal anesthesia. Moreover, Shabana et al.  in their study on 100 parturient scheduled for elective cesarean delivery under spinal anesthesia found that the intravenous 4-mg ondansetron significantly decreases hypotension, HR fluctuation, and the dose of vasopressor used. In contrast, Ortiz-Gómez et al.  in their postoperative randomized placebo-controlled trial on 128 pregnant women scheduled for elective cesarean delivery with spinal anesthesia found that prophylactic 2, 4, and 8 mg of ondansetron played no role in the prevention of postspinal hypotension or in reducing vasopressor consumption. Regarding the use of vasopressor, in our study, we found that there was a highly significant increase in controlled group in comparison with ondansetron group. In agreement with the results of this current study, Gao et al.  in their meta-analysis study of 10 randomized-controlled trials conducted on 863 parturient found that prophylactic ondansetron reduced the incidence of spinal anesthesia-induced hypotension and vasopressor consumption in parturient women and reduced the adverse effects, such as nausea and vomiting. In contrast, Terkawi et al.  reported that ondansetron premedication does not reduce the amount of vasopressor used. Regarding nausea and vomiting, in our study, we found that there was a highly significant increase in controlled group when compared with that in the ondansetron group. Supporting the current study, Ray et al.  in their study on 63 parturient women undergoing cesarean section under spinal anesthesia found that the intravenous ondansetron 4 mg before giving spinal anesthesia is more effective to prevent incidence of nausea and vomiting in cesarean section. On the contrary, in disagreement with our study, the study done by Terkawi et al.  reported that ondansetron premedication does not reduce the incidence of nausea and vomiting.
| Conclusion|| |
This study concluded that intravenous 4-mg ondansetron in parturient women undergoing elective cesarean section significantly decreases hypotension, bradycardia, nausea, vomiting, and the dose of vasopressor used.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]