Intrathecal fentanyl is superior to intravenous ondansetron for the prevention of perioperative nausea during cesarean delivery with spinal anesthesia

Commonly used antiemetics for prophylaxis of postoperative nausea and vomiting after Caesarean delivery with neuraxial morphine: a network meta-analysis

BACKGROUND

Dopamine antagonists, 5-HT3 antagonists, and dexamethasone are frequently used in obstetrics to prevent postoperative nausea and vomiting (PONV). However, the superiority of any drug class is yet to be established. This network meta-analysis aimed to compare the efficacy of these antiemetics for PONV prophylaxis in women receiving neuraxial morphine for Caesarean delivery.

METHODS

We searched PubMed, Embase, CENTRAL, Web of Science, and Wanfang Data for eligible randomised controlled trials. Primary outcomes were the incidences of postoperative nausea (PON) and postoperative vomiting (POV) within 24 h after surgery. We used a Bayesian random-effects model and calculated odds ratios with 95% credible intervals for dichotomous data. We performed sensitivity and subgroup analyses for primary outcomes.

RESULTS

A total of 33 studies with 4238 women were included. In the primary analyses of all women, 5-HT3 antagonists, dopamine antagonists, dexamethasone, and 5-HT3 antagonists plus dexamethasone significantly reduced PON and POV compared with placebo, and 5-HT3 antagonists plus dexamethasone were more effective than monotherapy. In the subgroup analyses, similar results were seen in women receiving epidural morphine or intrathecal morphine alone but not in women receiving intrathecal morphine with fentanyl or sufentanil. However, most included studies had some concerns or a high risk of bias, and the overall certainty of the evidence was low or very low.

CONCLUSIONS

Combined 5-HT3 antagonists plus dexamethasone are more effective than monotherapy in preventing PONV associated with neuraxial morphine after Caesarean delivery. Future studies are needed to determine the role of prophylactic antiemetics in women receiving intrathecal morphine and lipophilic opioids.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42023454602.

Epidural administration of 2% Mepivacaine after spinal anesthesia does not prevent intraoperative nausea and vomiting during cesarean section: A prospective, double-blinded, randomized controlled trial

BACKGROUND

Intraoperative nausea and vomiting (IONV) is a common symptom during cesarean section (CS) delivery causing significant discomfort to patients. Combined spinal and epidural anesthesia (CSEA) can provide both intraoperative anesthesia and postoperative analgesia. During CSEA, it is reasonable to administer local anesthetics to the epidural space before patient complaints to compensate for the diminished effect of spinal anesthesia. Therefore, we hypothesized that intraoperative epidural administration of 2% mepivacaine would reduce the incidence of IONV.

METHODS

Patients who were scheduled for elective CS were randomly allocated to 2 groups. Patients and all clinical staff except for an attending anesthesiologist were blinded to the allocation. After the epidural catheter was inserted at the T11-12 or T12-L1 interspace, spinal anesthesia was performed at the L2-3 or L3-4 interspace to intrathecally administer 10 mg of 0.5% hyperbaric bupivacaine. Twenty min after spinal anesthesia, either 5 mL of 2% mepivacaine (group M) or saline (group S) was administered through an epidural catheter. Vasopressors were administered prophylactically to keep both the systolic blood pressure ≥ 80 % of the baseline value with the absolute value ≥ 90 mm Hg and the mean blood pressure ≥ 60 mm Hg. The primary endpoint was the incidence of IONV. The secondary endpoints were degree of nausea, the degree and incidence of pain, and Bromage score.

RESULTS

Ninety patients were randomized, and 3 patients were excluded from the final analysis. There was no significant difference in the incidence of IONV between the groups (58% in group M and 61% in group S, respectively, P = .82). In contrast, the incidence and degree of intraoperative pain in group M were significantly lower compared to group S. In addition, the incidence of rescue epidural administration of fentanyl (18% vs 47%) or mepivacaine (2.3% vs 25%) for intraoperative pain was lower in group M compared to group S.

CONCLUSIONS

Our results indicate that epidural administration of 2% mepivacaine 20 minutes after spinal anesthesia does not reduce the incidence of IONV in CS under CSEA. However, intraoperative epidural administration of 2% mepivacaine was found to improve intraoperative pain.

Effects of intrathecal opioids on cesarean section: a systematic review and Bayesian network meta-analysis of randomized controlled trials

PURPOSE

We aimed to compare the beneficial and harmful effects of opioids used as adjuncts to local anesthetics in patients undergoing cesarean section under spinal anesthesia.

METHODS

We searched electronic databases and ClinicalTrials.gov from their inception until March, 2021 without language restrictions. The primary outcome was the complete analgesia duration (Time to VAS > 0). Data were synthesized using the Bayesian random-effects model. Evidence confidence was evaluated using the Confidence In Network Meta-Analysis.

RESULTS

We identified 66 placebo-controlled randomized controlled trials (RCTs) comprising 4400 patients undergoing elective cesarean section. Compared with the placebo, intrathecal opioids (fentanyl, sufentanil, and morphine) significantly prolonged the analgesia duration by 96, 96, and 190 min, respectively (mean difference). Despite morphine ranking first, opioid efficacy was similar; the results were inconsistent with respect to other analgesic outcomes. Except for diamorphine, all opioids were associated with significant increases in the pruritus incidence. Sufentanil and morphine were associated with increases in the respiratory depression incidence.

CONCLUSIONS

We confirmed that intrathecal opioids benefit postoperative analgesia. Although morphine seems to be the most appropriate agent, some results were inconsistent, and the evidence confidence was often moderate or low, especially for adverse outcomes. Well-designed RCTs with an evidence-based approach are imperative for determining the most appropriate opioid for cesarean sections.

Interventions for preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section

BACKGROUND

Nausea and vomiting are distressing symptoms which are experienced commonly during caesarean section under regional anaesthesia and in the postoperative period.  OBJECTIVES: To assess the efficacy of pharmacological and non-pharmacological interventions versus placebo or no intervention given prophylactically to prevent nausea and vomiting in women undergoing regional anaesthesia for caesarean section.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (16 April 2020), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of studies and conference abstracts, and excluded quasi-RCTs and cross-over studies.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Our primary outcomes are intraoperative and postoperative nausea and vomiting. Data entry was checked. Two review authors independently assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Eighty-four studies (involving 10,990 women) met our inclusion criteria. Sixty-nine studies, involving 8928 women, contributed data. Most studies involved women undergoing elective caesarean section. Many studies were small with unclear risk of bias and sometimes few events. The overall certainty of the evidence assessed using GRADE was moderate to very low. 5-HT3 antagonists: We found intraoperative nausea may be reduced by 5-HT3 antagonists (average risk ratio (aRR) 0.55, 95% confidence interval (CI) 0.42 to 0.71, 12 studies, 1419 women, low-certainty evidence). There may be a reduction in intraoperative vomiting but the evidence is very uncertain (aRR 0.46, 95% CI 0.29 to 0.73, 11 studies, 1414 women, very low-certainty evidence). There is probably a reduction in postoperative nausea (aRR 0.40, 95% CI 0.30 to 0.54, 10 studies, 1340 women, moderate-certainty evidence), and these drugs may show a reduction in postoperative vomiting (aRR 0.47, 95% CI 0.31 to 0.69, 10 studies, 1450 women, low-certainty evidence). Dopamine antagonists: We found dopamine antagonists may reduce intraoperative nausea but the evidence is very uncertain (aRR 0.38, 95% CI 0.27 to 0.52, 15 studies, 1180 women, very low-certainty evidence). Dopamine antagonists may reduce intraoperative vomiting (aRR 0.41, 95% CI 0.28 to 0.60, 12 studies, 942 women, low-certainty evidence) and postoperative nausea (aRR 0.61, 95% CI 0.48 to 0.79, 7 studies, 601 women, low-certainty evidence). We are uncertain if dopamine antagonists reduce postoperative vomiting (aRR 0.63, 95% CI 0.44 to 0.92, 9 studies, 860 women, very low-certainty evidence). Corticosteroids (steroids): We are uncertain if intraoperative nausea is reduced by corticosteroids (aRR 0.56, 95% CI 0.37 to 0.83, 6 studies, 609 women, very low-certainty evidence) similarly for intraoperative vomiting (aRR 0.52, 95% CI 0.31 to 0.87, 6 studies, 609 women, very low-certainty evidence). Corticosteroids probably reduce postoperative nausea (aRR 0.59, 95% CI 0.49 to 0.73, 6 studies, 733 women, moderate-certainty evidence), and may reduce postoperative vomiting (aRR 0.68, 95% CI 0.49 to 0.95, 7 studies, 793 women, low-certainty evidence). Antihistamines: Antihistamines may have little to no effect on intraoperative nausea (RR 0.99, 95% CI 0.47 to 2.11, 1 study, 149 women, very low-certainty evidence) or intraoperative vomiting (no events in the one study of 149 women). Antihistamines may reduce postoperative nausea (aRR 0.44, 95% CI 0.30 to 0.64, 4 studies, 514 women, low-certainty evidence), however, we are uncertain whether antihistamines reduce postoperative vomiting (average RR 0.48, 95% CI 0.29 to 0.81, 3 studies, 333 women, very low-certainty evidence). Anticholinergics: Anticholinergics may reduce intraoperative nausea (aRR 0.67, 95% CI 0.51 to 0.87, 4 studies, 453 women, low-certainty evidence) but may have little to no effect on intraoperative vomiting (aRR 0.79, 95% CI 0.40 to 1.54, 4 studies; 453 women, very low-certainty evidence). No studies looked at anticholinergics in postoperative nausea, but they may reduce postoperative vomiting (aRR 0.55, 95% CI 0.41 to 0.74, 1 study, 161 women, low-certainty evidence). Sedatives: We found that sedatives probably reduce intraoperative nausea (aRR 0.65, 95% CI 0.51 to 0.82, 8 studies, 593 women, moderate-certainty evidence) and intraoperative vomiting (aRR 0.35, 95% CI 0.24 to 0.52, 8 studies, 593 women, moderate-certainty evidence). However, we are uncertain whether sedatives reduce postoperative nausea (aRR 0.25, 95% CI 0.09 to 0.71, 2 studies, 145 women, very low-certainty evidence) and they may reduce postoperative vomiting (aRR 0.09, 95% CI 0.03 to 0.28, 2 studies, 145 women, low-certainty evidence). Opioid antagonists: There were no studies assessing intraoperative nausea or vomiting. Opioid antagonists may result in little or no difference to the number of women having postoperative nausea (aRR 0.75, 95% CI 0.39 to 1.45, 1 study, 120 women, low-certainty evidence) or postoperative vomiting (aRR 1.25, 95% CI 0.35 to 4.43, 1 study, 120 women, low-certainty evidence). Acupressure: It is uncertain whether acupressure/acupuncture reduces intraoperative nausea (aRR 0.55, 95% CI 0.41 to 0.74, 9 studies, 1221 women, very low-certainty evidence). Acupressure may reduce intraoperative vomiting (aRR 0.52, 95% CI 0.33 to 0.80, 9 studies, 1221 women, low-certainty evidence) but it is uncertain whether it reduces postoperative nausea (aRR 0.46, 95% CI 0.27 to 0.75, 7 studies, 1069 women, very low-certainty evidence) or postoperative vomiting (aRR 0.52, 95% CI 0.34 to 0.79, 7 studies, 1069 women, very low-certainty evidence). Ginger: It is uncertain whether ginger makes any difference to the number of women having intraoperative nausea (aRR 0.66, 95% CI 0.36 to 1.21, 2 studies, 331 women, very low-certainty evidence), intraoperative vomiting (aRR 0.62, 95% CI 0.38 to 1.00, 2 studies, 331 women, very low-certainty evidence), postoperative nausea (aRR 0.63, 95% CI 0.22 to 1.77, 1 study, 92 women, very low-certainty evidence) and postoperative vomiting (aRR 0.20, 95% CI 0.02 to 1.65, 1 study, 92 women, very low-certainty evidence). Few studies assessed our secondary outcomes including adverse effects or women's views.

AUTHORS' CONCLUSIONS

This review indicates that 5-HT3 antagonists, dopamine antagonists, corticosteroids, sedatives and acupressure probably or possibly have efficacy in reducing nausea and vomiting in women undergoing regional anaesthesia for caesarean section. However the certainty of evidence varied widely and was generally low. Future research is needed to assess side effects of treatment, women's views and to compare the efficacy of combinations of different medications.

Effect of continuous infusion of a subhypnotic dose of propofol on nausea and vomiting after carboprost administration at cesarean delivery: A randomized, double-blind, placebo-controlled trial

OBJECTIVE

To investigate whether continuous infusion of propofol at a subhypnotic dose prevents nausea and vomiting following carboprost administration at cesarean delivery.

METHODS

A prospective, randomized, double-blind, placebo-controlled trial conducted at West China Second University Hospital, from June 28, 2017 to January 30, 2018. Pregnant women were randomly allocated to propofol or saline infusion immediately before receiving carboprost at cesarean delivery under combined spinal-epidural (CSE) anesthesia. Propofol was given at an infusion rate of 1.0 mg/kg/h following a loading dose of 0.3 mg/kg. Primary outcome was incidence of intraoperative nausea and vomiting (IONV). Potential sedative effect of propofol infusion was assessed using Modified Observer's Assessment of Alertness and Sedation (MOAA/S) scoring and continuous Bispectral Index (BIS) monitoring.

RESULTS

The incidence of IONV was lower in patients who received propofol compared with saline (46.7% vs 76.7%, OR 0.27; 95% CI, 0.092-0.78, P = 0.016 for nausea; 26.7% vs 53.3%, OR 0.50; 95% CI, 0.25-0.95, P = 0.032 for retching; 10.0% vs 50.0%, OR 0.11; 95% CI, 0.03-0.44, P < 0.001 for vomiting). There were no differences in MOAA/S scoring or BIS between the two groups.

CONCLUSION

A subhypnotic dose of propofol reduces the incidence of nausea and vomiting following carboprost administration at cesarean delivery under CSE anesthesia, without measurable effect on patients' consciousness or alertness. ClincalTrials.gov: NCT03185156.

Efficacy of Electroacupuncture Combined with Tropisetron in Treating Carboprost Tromethamine-Induced Nausea and Vomiting during Cesarean Section under Lumbar Anesthesia

OBJECTIVE

We evaluated the efficacy of electroacupuncture combined with tropisetron in treating carboprost tromethamine-induced nausea and vomiting during cesarean section under lumbar anesthesia.

METHODS

A total of 264 patients aged 22-40 years were enrolled, who received carboprost tromethamine and suffered nausea and vomiting during cesarean section under lumbar anesthesia. The patients were divided randomly into the control group, electroacupuncture group, tropisetron group, and electroacupuncture + tropisetron group.

RESULTS

Compared to the control group, the nausea and vomiting scores decreased at T3 in both the electroacupuncture and electroacupuncture + tropisetron groups, and decreased at T4 in the electroacupuncture group, tropisetron group, and electroacupuncture + tropisetron group; the motilin, gastrin, and 5-hydroxytryptamine (5-HT) levels decreased at T5 in the other 3 groups. Compared to the electroacupuncture + tropisetron group, the nausea and vomiting scores increased at T3 in the control and tropisetron groups, and increased at T4 in the other 3 groups; the motilin, gastrin, and 5-HT levels increased at T5.

CONCLUSIONS

Our study suggested that electroacupuncture combined with tropisetron could effectively relieve carboprost tromethamine-induced nausea and vomiting during cesarean section under lumbar anesthesia. The effect was better than its single application, and the reduced 5-HT, motilin, and gastrin levels might be involved in the underlying mechanism.

The optimum management of nausea and vomiting during and after cesarean delivery

Intraoperative and postoperative nausea and vomiting (IONV and PONV) afflict up to 80% of parturients undergoing cesarean delivery with neuraxial anesthesia. Preventing nausea and emesis is a top priority for women undergoing cesarean delivery and is included in the quality of recovery measures and enhanced recovery after cesarean delivery protocols. The majority of known perioperative emetic triggers can be avoided or mitigated by optimizing anesthetic and surgical management. IONV may arise from spinal anesthesia-induced hypotension, intraoperative pain, and medications such as uterotonics and antibiotics. Furthermore, uterine exteriorization and peritoneal irrigation increase IONV risk. Conversely, preventing PONV mainly focuses on optimizing analgesia through an opioid-sparing, multimodal strategy. In addition, combination prophylactic antiemetic therapy should be instituted in this high-risk population to further reduce the risk of IONV and PONV.

Sequential intrathecal injection of fentanyl and hyperbaric bupivacaine at different rates: does it make a difference? A randomized controlled trial

Background

Previous studies have shown that sequential intrathecal injection of fentanyl and hyperbaric bupivacaine for cesarean section (CS) anesthesia provides a superior anesthetic effect than use of bupivacaine alone, and prolongs postoperative analgesia. Herein, we investigated whether rapid intrathecal injection of fentanyl followed by slow injection of hyperbaric bupivacaine affects the duration of postoperative analgesia, the effectiveness of anesthesia, and hemodynamic status.

Methods

Fifty-six parturients with American Society of Anesthesiologists physical status I or II, aged 18–40 years, and scheduled to undergo elective CS were randomly assigned to 2 groups of 28 patients each. The normal sequential group received sequential intrathecal injections of fentanyl and hyperbaric bupivacaine at the same rate, each with a 5 ml syringe. The rapid sequential group received a rapid intrathecal injection of fentanyl with an insulin syringe, followed by a slow injection of hyperbaric bupivacaine with a 5 ml syringe. The onset of sensory block, the timing of the first rescue analgesia, the doses of rescue analgesics, the degree of postoperative pain, the onset and duration of motor block, the incidence and duration of hypotension, and spinal anesthesia-related complications were recorded.

Results

While both approaches had comparable spinal anesthesia-related complications, incidence and duration of hypotension, and doses of ephedrine, the rapid sequential group exhibited a more rapid onset of sensory block, a higher sensory level, and more prolonged postoperative analgesia.

Conclusions

Rapid sequential injection of fentanyl and hyperbaric bupivacaine produced superior anesthesia and more prolonged postoperative analgesia than sequential injections of both at the same rate.

Palonosetron Versus Ramosetron Prophylaxis for Control of Postoperative Nausea and Vomiting after Cesarean Delivery under Spinal Anesthesia

PURPOSE

Postoperative nausea and vomiting (PONV) after spinal anesthesia for cesarean delivery are distressing to both patients and surgeons. This study was designed to evaluate the efficacy and safety of palonosetron and ramosetron (both newer and highly potent 5HT3 receptor antagonists) in nausea and vomiting in cesarean delivery after spinal anesthesia.

METHODS

In this randomized, double-blind study, 109 women received either palonosetron (0.075 mg) or ramosetron (0.3 mg) intravenously immediately after clamping of the fetal umbilical cord. Nausea, vomiting, adverse events, and overall satisfaction were then observed for 48 h after administration of spinal anesthesia.

RESULTS

A complete response (defined as no postoperative nausea and vomiting) during first 0-2 h postoperative after administration of spinal anesthesia was achieved in 85.5 % of patients with palonosetron and in 83.3 % of patients with ramosetron (p > 0.05). However, the corresponding incidence during 2 to 24 h was 70.9 and 53.7 %, respectively (p < 0.05), while it was 63.3 and 44.4 % at 24-48 h after anesthesia (p < 0.05). Along with a more complete response, the severity of nausea was also lesser with palonosetron during the corresponding study periods (2-24 and 24-48 h, respectively; p < 0.05). Patients who received palonosetron were also more satisfied than those who received ramosetron (p < 0.05). No difference in adverse events was observed in any of the groups.

CONCLUSION

To conclude, prophylactic therapy with palonosetron is more effective than prophylactic therapy with ramosetron for the long-term prevention of PONV after cesarean section.

Interventions at caesarean section for reducing the risk of aspiration pneumonitis

BACKGROUND

Aspiration pneumonitis is a syndrome resulting from the inhalation of gastric contents. The incidence in obstetric anaesthesia has fallen, largely due to improved anaesthetic techniques and the increased use of regional anaesthesia at caesarean section. However, aspiration pneumonitis is still a cause of maternal morbidity and mortality, and it is important to use effective prophylaxis.

OBJECTIVES

To determine whether interventions given prior to caesarean section reduce the risk of aspiration pneumonitis in women with an uncomplicated pregnancy.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 April 2013).

SELECTION CRITERIA

Randomised controlled trials were included. Quasi-randomised trials were excluded.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked. Fixed-effect meta-analysis was used to combine data where it was reasonable to assume that studies were estimating the same underlying treatment effect. If substantial clinical or statistical heterogeneity was detected, we used random-effects analysis to produce an overall summary.

MAIN RESULTS

Thirty-two studies were included in this review. However, only 22 studies, involving 2658 women, provided data for analysis. All the women in the included studies had a caesarean section under general anaesthesia. The studies covered a number of comparisons, but were mostly small and of unclear or poor quality.When compared with no treatment or placebo, there was a significant reduction in the risk of intragastric pH < 2.5 with antacids (risk ratio (RR) 0.17, 95% confidence interval (CI) 0.09 to 0.32, two studies, 108 women), H2 antagonists (RR 0.09, 95% CI 0.05 to 0.18, two studies, 170 women) and proton pump antagonists (RR 0.26, 95% CI 0.14 to 0.46, one study 80 women). H2 antagonists were associated with a reduced the risk of intragastric pH < 2.5 at intubation when compared with proton pump antagonists (RR 0.39, 95% CI 0.16 to 0.97, one study, 120 women), but compared with antacids the findings were unclear. The combined use of 'antacids plus H2 antagonists' was associated with a significant reduction in the risk of intragastric pH < 2.5 at intubation when compared with placebo (RR 0.02, 95% CI 0.00 to 0.15, one study, 89 women) or compared with antacids alone (RR 0.12, 95% CI 0.02 to 0.92, one study, 119 women).

AUTHORS' CONCLUSIONS

The quality of the evidence was poor, but the findings suggest that the combination of antacids plus H2 antagonists was more effective than no intervention, and superior to antacids alone in preventing low gastric pH. However, none of the studies assessed potential adverse effects or substantive clinical outcomes. These findings are relevant for all women undergoing caesarean section under general anaesthesia.

Prophylactic ondansetron does not prevent shivering or decrease shivering severity during cesarean delivery under combined spinal epidural anesthesia: a randomized trial

OBJECTIVES

Cesarean delivery is commonly performed under regional anesthesia, which is often associated with maternal shivering. This can cause distress and interfere with monitoring. The study objective was to evaluate the antishivering efficacy of ondansetron, which reduces the incidence and severity of shivering in nonobstetric patients. We hypothesized that there would be a significant decrease in the incidence and/or severity of shivering in women who are given intravenous ondansetron 8 mg before combined spinal epidural (CSE) anesthesia, when compared with placebo.

METHODS

This was a randomized, double-blinded, parallel-group, placebo-controlled trial of 118 women scheduled for elective cesarean surgery. Women received either intravenous ondansetron 8 mg (n = 58) or saline (n = 60) before CSE anesthesia (intrathecal hyperbaric bupivacaine 0.5% 2.2-2.5 mL plus fentanyl 15 μg). The incidence and severity of shivering, measured on a validated 5-point scale, and other outcomes, such as nausea, pruritus, headache, or satisfaction, were assessed at 3 time points during the surgery and postoperative period.

RESULTS

The incidence of shivering at any time point did not differ significantly between groups: ondansetron 41% versus placebo 47% (P = 0.54). The incidence of severe shivering at any time was not significantly different: ondansetron 32% versus placebo 33% (P = 0.79). There were no significant differences between the groups for any secondary outcomes.

CONCLUSIONS

Intravenous ondansetron 8 mg before performing CSE anesthesia in women undergoing elective cesarean delivery does not decrease the incidence or severity of shivering.

Antiemetic effects of dexamethasone and ondansetron combination during cesarean sections under spinal anaesthesia

BACKGROUND

Nausea and vomiting are frequently seen in patients undergoing cesarean section (CS) under regional anesthesia. We aimed to compare the antiemetic efficacy of ondansetron and dexamethasone combination with that of the use of each agent alone to decrease the incidence of post-delivery intraoperative nausea and vomiting (IONV) during CS under spinal anesthesia.

OBJECTIVE

To compare the antiemetic efficacy of ondansetron and dexamethasone combination with that of the single use of each agent to decrease the incidence of postdelivery IONV during CS under spinal anesthesia.

METHODS

A randomized, prospective, double blind study was performed on 90 patients undergoing planned CS under spinal anesthesia. Patients received 4mg ondansetron in Group O, 8mg dexamethasone in GroupD, 4mg ondansetron+8mg dexamethasone in Group OD intravenously within 1-2 minutes after the umbilical cord was clamped. Frequency of postdelivery IONV episodes was recorded.

RESULTS

A total of 86 eligible patients were included in the study. There were 29 patients in Group O, 29 patients in Group D and 28 patients in Group OD. There were no statistically significant difference between the groups in terms of baseline characteristics and intraoperative managements. Frequency of intraoperative nausea, retching and vomiting experiences were similar between the groups (p>0.05).

CONCLUSION

Single dose 4mg ondansetron, 8mg dexamethasone, or combined use of 8mg dexamethasone+4mg ondansetron, given intravenously is all effective agents for the control of postdelivery IONV. Combined use of dexamethasone and ondansetron for the same indication does not seem to increase the antiemetic efficacy.

Minimum appropriate dose of lidocaine with a fixed dose of sufentanil epinephrine used for spinal anesthesia in caesarian section

Background

Caesarian section is a commonplace surgery in females for which spinal anesthesia is the preferred method. The local anesthetic medications used in the surgery are often associated with complications such as nausea, vomiting, dyspnea, hypotension, and bradycardia. In the present study, we decreased the dose of the anesthetic drug and added an opioid instead.

Objectives

We tried to find an appropriate combination of medications required for optimal anesthesia with minimum complications.

Patients and Methods

One hundred twenty six candidates for C/S with first and second class ASA aged 18-35 years were randomly divided into three groups. All patients received sufentanil (2.5 µg) and epinephrine (100 µg) doses but the lidocaine doses were respectively 50 mg, 60 mg and 75 mg in the groups 1, 2 and 3. Complications including hypotension, bradycardia, dyspnea, nausea, vomiting, and anesthesia quality were recorded and statistically analyzed.

Results

The level of anesthesia was significantly different between groups. By reducing the lidocaine dose, patients with anesthesia level under the nipple increased but the surgeon and the patient were satisfied with the results. Nausea, vomiting, and dyspnea was degraded by decreasing the lidocaine dose especially in the 50 mg group. The need to use ephedrine was directly associated with the lidocaine. However, the need to use atropine was not significantly different between groups. Pruritus was not significantly different as well.

Conclusions

It seems that reducing the lidocaine dose, when combined with sufentanil, decreases most complications of spinal anesthesia such as hypotension, dyspnea, nausea, and vomiting while preserving anesthesia quality.

Randomized, placebo-controlled trial of granisetron for control of nausea and vomiting during cesarean delivery under spinal anesthesia

OBJECTIVES

The objective of this study was to evaluate the efficacy and safety of granisetron (5HT3 receptor antagonist) on the incidence of nausea and vomiting in cesarean deliveries under spinal anesthesia.

METHODS

In the randomized, double-blind study, 80 parturients received granisetron 40 μg/kg or placebo (n = 40 each) intravenously, immediately after clamping of the fetal umbilical cord. Nausea, vomiting, and adverse events were then observed for 24 h after administration of spinal anesthesia.

RESULTS

A complete response (defined as no postoperative nausea and vomiting) during 0-4 h after administration of spinal anesthesia was achieved in 80 % of patients with granisetron and in 45 % of patients with placebo. The corresponding incidences during (4-24 h) were 82.5 and 55 % (P value <0.05). No difference in adverse events was observed in any of the groups.

CONCLUSIONS

Prophylactic use of granisetron is effective for preventing emetic episodes during spinal anesthesia for cesarean delivery.

Interventions for preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section

BACKGROUND

Nausea and vomiting are distressing symptoms which are experienced commonly during caesarean section under regional anaesthesia and can also occur in the period following the procedure. 

OBJECTIVES

To assess the efficacy of pharmacological and non-pharmacological interventions given prophylactically to prevent nausea and vomiting in women undergoing regional anaesthesia for caesarean section.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (27 February 2012) and reference lists of identified studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and excluded quasi-RCTs and cross-over studies.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked.  

MAIN RESULTS

Fifty-two studies met the inclusion criteria but only 41 studies, involving 5046 women, provided useable data for the review involving women having caesareans under regional anaesthesia. The majority of the studies involved women undergoing elective caesarean section. Only two studies included emergency surgery, however, they did not stratify data according to type of surgery. The studies covered numerous comparisons, but the majority of studies involved 5-HT(3) receptor antagonists, dopamine receptor antagonists, corticosteroids or acupressure. Studies were mainly small and of unclear quality.Three classes of intervention were found to be effective in at least three out of four of our primary outcomes (intraoperative nausea, intraoperative vomiting, postoperative nausea and postoperative vomiting). These interventions were 5-HT(3) antagonists, dopamine antagonists and sedatives. Other classes of intervention were effective for fewer than three of our primary outcomes.With 5-HT antagonists, we found a reduction in intraoperative nausea (average risk ratio (RR) 0.64, 95% confidence interval (CI) 0.46 to 0.88, eight studies, 720 women). There were also reductions in postoperative nausea (average RR 0.40, 95% CI 0.25 to 0.64, four studies, 405 women) and vomiting (average RR 0.50, 95% CI 0.32 to 0.77, five studies, 565 women). We did not detect a significant reduction in intraoperative vomiting (average RR 0.56, 95% CI 0.31 to 1.00, seven studies, 668 women).Dopamine antagonists demonstrated a reduction in intraoperative nausea (average RR 0.38, 95% CI 0.25 to 0.57, nine studies, 636 women) and intraoperative vomiting (average 0.39, 95% CI 0.24 to 0.64, eight studies, 536 women), with similar reductions in postoperative nausea (average RR 0.60, 95% CI 0.40 to 0.91, five studies, 412 women) and vomiting (average RR 0.57, 95% CI 0.36 to 0.91, six studies, 472 women). These differences were observed with both metoclopramide and droperidol.Sedatives (most commonly propofol) demonstrated a reduction in intraoperative nausea (average RR 0.71, 95% CI 0.52 to 0.96, four studies, 285 women) and intraoperative vomiting (average RR 0.42, 95% CI 0.26 to 0.68, four studies, 285 women), also with a reduction in postoperative nausea (average RR 0.25, 95% CI 0.09 to 0.71, two studies 145 women) and vomiting (average RR 0.09, 95% CI 0.03 to 0.28, two studies, 145 women).Acupressure was found to be effective for intraoperative nausea (average RR 0.59, 95% CI 0.38 to 0.90, six studies, 649 women) but not postoperative nausea (average RR 0.83, 95% CI 0.68 to 1.00, three studies, 429 women). Acupressure was not effective at reducing vomiting either intraoperatively (average RR 0.74, 95% CI 0.46 to 1.18, six studies, 649 women) or postoperatively (average RR 0.69, 95% CI 0.45 to 1.06, three studies, 429 women).Other effective intervention classes included corticosteroids, antihistamines, and anticholinergics.There were insufficient data to demonstrate any class of intervention was superior to another. There were no significant differences observed in the comparison of combined versus single interventions.Few studies assessed our secondary outcomes or the incidence of adverse effects. However, one study showed an increase in respiratory depression with sedation (midazolam) compared with dopamine antagonists.

AUTHORS' CONCLUSIONS

This review indicates that many different interventions have efficacy in preventing nausea and vomiting in women undergoing regional anaesthesia for caesarean section. There is little evidence that combinations of treatment are better than single agents.

Metoclopramide for nausea and vomiting prophylaxis during and after Caesarean delivery: a systematic review and meta-analysis

Nausea and vomiting occur commonly during and after Caesarean delivery (CD) performed under neuraxial anaesthesia. Metoclopramide is a prokinetic agent reported to be safe in parturients. This meta-analysis assesses the efficacy of metoclopramide for prophylaxis against intra- and postoperative nausea and vomiting (IONV and PONV) in parturients undergoing CD under neuraxial anaesthesia. We performed a literature search of MEDLINE (1966-2011), Cochrane Central Register of Controlled Trials, EMBASE (1947-2011), Google scholar, and CINAHL for randomized controlled trials which compared metoclopramide with placebo in women having CD under neuraxial anaesthesia. Eleven studies with 702 patients were included in the analysis. Administration of metoclopramide (10 mg) resulted in a significant reduction in the incidence of ION and IOV when given before block placement [relative risk (RR) (95% confidence interval, 95% CI)=0.27 (0.16, 0.45) and 0.14 (0.03, 0.56), respectively] or after delivery [RR (95% CI)=0.38 (0.20, 0.75) and 0.34 (0.18, 0.66), respectively]. The incidence of early (0-3 or 0-4 h) PON and POV [RR (95% CI)=0.47 (0.26, 0.87) and 0.45 (0.21, 0.93), respectively] and overall (0-24 or 3-24 h) PON (RR 0.69; 95% CI 0.52, 0.92) were also reduced with metoclopramide. Extra-pyramidal side-effects were not reported in any patient. In conclusion, this review suggests that metoclopramide is effective and safe for IONV and PONV prophylaxis in this patient population. Given the quality of the studies and the infrequent use of neuraxial opioids, these results should be interpreted with caution in current practice and further studies are needed to confirm those findings.

Study of equivalence: spinal bupivacaine 15 mg versus bupivacaine 12 mg with fentanyl 15 μg for cesarean delivery

BACKGROUND

A safe and effective intrathecal dose of bupivacaine alone for cesarean delivery has not yet been established. This study tested the hypothesis that an intrathecal dose of hyperbaric bupivacaine 15 mg would produce equivalent spinal anesthesia for cesarean delivery as the combination of hyperbaric bupivacaine 12 mg and fentanyl 15 μg.

METHODS

This was a single center, double-blind, randomized clinical trial of equivalence. One hundred and thirty-eight healthy parturients scheduled for elective cesarean delivery were randomized to receive either intrathecal hyperbaric bupivacaine 15 mg (Group B) or hyperbaric bupivacaine 12 mg with fentanyl 15 μg (Group BF). Parturients where asked to describe their degree of sensation during surgery using a four-point scale 20 min after spinal injection. Secondary outcomes included the incidence of maternal side effects, maternal hemodynamics and the need for supplemental analgesia.

RESULTS

There was no difference in the quality of anesthesia between the two groups. Sixty-eight of 69 and 69/69 patients in Group B and Group BF, respectively had anesthesia classified as successful (RR=1.01; 95% CI 0.85, 1.22). The only two secondary outcomes that were different between the groups were the largest change in mean arterial pressure (decrease of 40 mmHg and 34 mmHg for Group B and Group BF, respectively; P=0.004) and the incidence of nausea (59% and 35% for Group B and Group BF, respectively; P=0.006).

CONCLUSION

There was no difference in the degree of sensation at 20 min between Group B and Group BF. The only significant differences between the two techniques were a higher incidence of nausea and decrease in maternal blood pressure in Group B.

Intrathecal fentanyl added to bupivacaine and morphine for cesarean delivery may induce a subtle acute opioid tolerance

BACKGROUND

Previous studies have demonstrated that the addition of intrathecal fentanyl to a spinal anesthetic for cesarean delivery improves intraoperative analgesia. However, intrathecal fentanyl may induce acute tolerance to opioids. The objective of this study was to investigate whether the addition of intrathecal fentanyl to spinal anesthesia with intrathecal morphine increases postoperative analgesic requirements and pain scores.

METHODS

In this randomized, double-blinded study, 40 women having elective cesarean delivery were enrolled. Patients received spinal anesthesia with hyperbaric bupivacaine 12 mg, morphine 200 μg, and fentanyl 0, 5, 10 or 25 μg. Each patient received intravenous patient-controlled analgesia morphine for 24h postoperatively. Outcome measures included postoperative morphine usage and pain scores, as well as intraoperative pain, nausea, hypotension and vasopressor use.

RESULTS

Total morphine use over the 24-h post-spinal study period was similar among the study groups (P=0.129). Postoperative pain scores were higher in patients receiving fentanyl 5, 10 and 25 μg compared to fentanyl 0 μg control group (P=0.003).

CONCLUSIONS

The study results suggest that intrathecal fentanyl may induce acute tolerance to intrathecal morphine. However, because there was no difference in postoperative analgesia requirement and the difference in pain scores was small, the clinical significance of this finding is uncertain.

Interventions at caesarean section for reducing the risk of aspiration pneumonitis

BACKGROUND

Aspiration pneumonitis is a syndrome resulting from the inhalation of gastric contents. The incidence in obstetric anaesthesia has fallen, largely due to improved anaesthetic techniques and the increased use of regional anaesthesia at caesarean section. However, aspiration pneumonitis is still a cause of maternal morbidity and mortality, and it is important to use effective prophylaxis.

OBJECTIVES

To determine whether interventions given prior to caesarean section reduce the risk of aspiration pneumonitis in women with an uncomplicated pregnancy.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2009).

SELECTION CRITERIA

Randomised controlled trials were included. Quasi-randomised trials were excluded.

DATA COLLECTION AND ANALYSIS

Authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked.

MAIN RESULTS

Twenty-two studies, involving 2658 women, are included, all having a caesarean section under general anaesthesia. The studies covered a number of comparisons, but were mostly small and of unclear or poor quality.When compared to no treatment or placebo, there was a significant reduction in the risk of intragastric pH < 2.5 with antacids (risk ratio (RR) 0.17, 95% confidence interval (CI) 0.09 to 0.32, two studies, 108 women), H(2) antagonists (RR 0.09, 95% CI 0.05 to 0.18, two studies, 170 women) and proton pump antagonists (RR 0.26, 95% CI 0.14 to 0.46, one study 80 women). H(2) antagonists were associated with a reduced the risk of intragastric pH < 2.5 at intubation when compared with proton pump antagonists (RR 0.39, 95% CI 0.16 to 0.97, one study, 120 women), but compared with antacids the findings were unclear. The combined use of 'antacids plus H(2) antagonists' was associated with a significant reduction in the risk of intragastric pH < 2.5 at intubation when compared with placebo (RR 0.02, 95% CI 0.00 to 0.15, one study, 89 women) or compared with antacids alone (RR 0.12, 95% CI 0.02 to 0.92, one study, 119 women).

AUTHORS' CONCLUSIONS

The quality of the evidence was poor, but the findings suggest that the combination of antacids plus H(2) antagonists was more effective than no intervention, and superior to antacids alone in preventing low gastric pH. However, none of the studies assessed potential adverse effects or substantive clinical outcomes. These findings are relevant for all women undergoing caesarean section under general anaesthesia.

Is there an advantage in using low-dose intrathecal bupivacaine for cesarean section?

PURPOSE

Spinal anesthesia for cesarean section is associated with a high incidence of maternal hypotension. The aim of this study was to assess the efficacy of low-dose bupivacaine with fentanyl to reduce the incidence of hypotension in spinal anesthesia for cesarean section.

METHODS

Forty pregnant women undergoing elective cesarean section were randomly allocated to two groups; those receiving 10 mg bupivacaine to group B (n = 20) and those receiving 4 mg bupivacaine plus 25 microg fentanyl to group BF (n = 20); the agents were given intrathecally with patients in the sitting position, with a combined spinal-epidural technique.

RESULTS

Sensory block was adequate for surgery in all patients. Hypotension occurred in all patients in group B (100%) and in 15 patients in group BF (75%). The incidence of hypotension, number of ephedrine treatments, and need for ephedrine were significantly greater in group B than group BF. Three patients in group BF required i.v. fentanyl supplementation after delivery. In 1 of these patients, i.v. fentanyl was not adequate, and epidural supplementation of 1% lidocaine was required.

CONCLUSION

The development of hypotension after spinal block in subjects undergoing cesarean section was not prevented despite low-dose (4 mg) bupivacaine plus 25 microg fentanyl, but the severity of maternal hypotension, and the number of ephedrine treatments and the total dose of ephedrine were decreased.

Complications of Exteriorized Compared With In Situ Uterine Repair at Cesarean Delivery Under Spinal Anesthesia

OBJECTIVE

To compare intraoperative complications of exteriorized and in situ uterine repair during elective cesarean delivery under spinal anesthesia.

METHODS

This study was a randomized, single-blinded trial in 80 women undergoing elective cesarean delivery under spinal anesthesia. Patients were randomly assigned to exteriorized or in situ uterine repair. Obstetricians were asked to perform assisted delivery of the placenta. Spinal anesthesia and oxytocin management were standardized. Phenylephrine was used to maintain systolic blood pressure within 10% of the baseline. The primary outcome was intraoperative, postdelivery nausea or vomiting.

RESULTS

Postdelivery nausea or vomiting (18% compared with 38%; P=.04) and tachycardia (3% compared with 18%; P=.03) were significantly reduced in the in situ group compared with the exteriorized group. The duration of uterine repair was significantly shorter in the exteriorized group (median 10 minutes [first and third quartiles 9, 13], compared with 11 minutes [9, 15]) (P=.04). The duration of surgery (36 minutes [30, 41] compared with 37 minutes [30, 45]) and estimated blood loss (mean+/-standard deviation 625+/-489 mL compared with 653+/-416 mL) were similar between the in situ and the exteriorized groups. There was no correlation between duration of uterine repair and estimated blood loss.

CONCLUSION

Exteriorization of the uterus for repair is associated with an increased incidence of nausea and vomiting and tachycardia during cesarean delivery under spinal anesthesia. Uterine repair should be done in situ where possible.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00452972

LEVEL OF EVIDENCE

I.

Anaesthesia for caesarean section

Although anaesthesia for Caesarean section is predominantly performed using regional techniques of anaesthesia, general anaesthesia will remain essential for subgroups of obstetric patients, especially those who are at high risk of complications. In the present review, recent reports that addressed issues regarding general and regional anaesthesia in Caesarean section will be discussed.

P6 acupressure does not prevent emesis during spinal anesthesia for cesarean delivery

Nausea and vomiting are major adverse effects during spinal anesthesia for cesarean delivery. Stimulation of the P6 (Neiguan) acupoint is a traditional Chinese acupuncture technique used for effective antiemetic purposes. In this study, we evaluated the antiemetic effect of P6 acupressure in parturients during spinal anesthesia for cesarean delivery. In a randomized, double-blind, controlled trial, 110 parturients scheduled for elective cesarean delivery were enrolled in the study. Thirty minutes before initiation of spinal anesthesia, parturients were randomized to acupressure bands or placebo bands bilaterally on the P6 acupoint and nausea and vomiting were observed over the study period. There were no statistically significant differences in maternal characteristics. Incidence rates for intraoperative nausea were 64% (acupressure group) and 71% (control group) (P = 0.416), with an incidence of intraoperative vomiting of 22% (acupressure group) and 27% (control group) (P = 0.506). The results suggest that prophylactic use of acupressure bands bilaterally on the P6 acupoint failed to prevent nausea and vomiting during spinal anesthesia for cesarean delivery.

Post-Cesarean Delivery Analgesia

Post-cesarean delivery pain relief is important. Good pain relief will improve mobility and can reduce the risk of thromboembolic disease, which is increased during pregnancy. Pain may also impair the mother's ability to optimally care for her infant in the immediate postpartum period and may adversely affect early interactions between mother and infant. Pain and anxiety may also reduce the ability of a mother to breast-feed effectively. It is necessary that pain relief be safe and effective, that it not interfere with the mother's ability to move around and care for her infant, and that it result in no adverse neonatal effects in breast-feeding women. The most commonly used modalities are systemic administration of opioids, either by intramuscular injection or i.v. by patient-controlled analgesia, and neuraxial injection of opioid as part of a regional anesthetic for cesarean delivery. These techniques have specific advantages and disadvantages which will be discussed in this review. In addition, there are new drug applications of potential benefit for the treatment of post-cesarean delivery pain.

Intraoperative nausea and vomiting during cesarean section under regional anesthesia

Nausea and vomiting during regional anesthesia for cesarean section are very common and unpleasant events. They cause significant distress to the patient and also interfere with the surgical procedure. They have multiple etiologies, which include hypotension, vagal hyperactivity, visceral pain, i.v. opioid supplementation, uterotonic agents and motion. The obstetric anesthesia literature has addressed these causative factors for nausea and vomiting individually, making it difficult for the anesthesiologists to have a comprehensive understanding of these important complications. This review highlights the anesthetic and non-anesthetic causes of intraoperative nausea and vomiting during regional anesthesia for cesarean section and the appropriate prophylactic and therapeutic management. Intraoperative nausea and vomiting can be best prevented by controlling hypotension, optimizing the use of neuraxial and i.v. opioids, improving the quality of block, minimizing surgical stimuli and judicious administration of uterotonic agents. Although prophylactic antiemetics have been advocated during cesarean sections, strict adherence to these practices can effectively lower the incidence of intraoperative nausea and vomiting without the requirement of antiemetic agents. Antiemetics, therefore, should be reserved for the prevention of intraoperative nausea and vomiting in high-risk patients and for the treatment of nausea and vomiting not responding to routine measures.

Effect of varying doses of fentanyl with low dose spinal bupivacaine for caesarean delivery in patients with pregnancy-induced hypertension

The purpose of this study was to evaluate haemodynamic stability, perioperative analgesia and neonatal outcome following intrathecal 0.5% bupivacaine 7.5 mg with varying doses of fentanyl, in parturients with pregnancy-induced hypertension. Forty-five parturients with pregnancy-induced hypertension scheduled for caesarean section were randomly allocated to receive 7.5 mg bupivacaine with saline 1 mL (group B), fentanyl 10 microg (group Bf10) or fentanyl 20 microg (group Bf20) intrathecally. Heart rate, blood pressure, and sensory block were recorded at regular intervals. Pain, nausea, vomiting, pruritus or any other side effects were sought. Neonatal outcome was assessed using Apgar score and umbilical artery blood gas analysis. Adequate surgical anaesthesia was established in all three groups. There was a statistically significant fall in mean arterial pressure in all three groups within 4-6 min of subarachnoid block (P<0.05), but the decrease in MAP was <20% of baseline in all three groups. Pain and discomfort during surgery were experienced more frequently in group B than in groups Bf10 and Bf20 (P<0.05). Duration of postoperative analgesia was significantly longer in group Bf20 (5.55+/-1.18 h) than in group Bf10 (3.97+/-2.12 h) and group B (3.27+/-1.8 h) (P<0.05). Neonatal outcome was similar in the three groups. Intrathecal fentanyl with low dose bupivacaine provides good surgical anaesthesia and prolongs the duration of analgesia without haemodynamic or neonatal compromise in patients with pregnancy-induced hypertension undergoing caesarean delivery.

An unexpected adverse drug effect

Adverse drug-drug interactions can occur between active and/or inactive ingredients in different formulations. The occurrence of a disulfiram reaction that developed postpartum following a 7-day course of metronidazole is presented. The case is presented, followed by a discussion of the mechanism of action and treatment. Recommendations for prevention of adverse drug effects are reviewed.

Intrathecal versus intravenous fentanyl for supplementation of subarachnoid block during cesarean delivery

Forty-eight healthy parturients scheduled for elective cesarean delivery were randomly allocated to receive intrathecally either 12 mg of hyperbaric bupivacaine plus 12.5 microg of fentanyl (n = 23) or bupivacaine alone (n = 25). In the latter group, IV 12.5 microg of fentanyl was administered immediately after spinal anesthesia. We compared the amount of IV fentanyl required for supplementation of the spinal anesthesia during surgery, the intraoperative visual analog scale, the time to the first request for postoperative analgesia, and the incidence of adverse effects. Additional IV fentanyl supplementation amounting to a mean of 32 +/- 35 microg was required in the IV Fentanyl group, whereas no supple- mentation was required in the Intrathecal Fentanyl group (P = 0.009). The time to the first request for postoperative analgesia was significantly longer in the Intrathecal Fentanyl group than in the IV Fentanyl group (159 +/- 39 min versus 119 +/- 44 min; P = 0.003). The incidence of systolic blood pressure <90 mm Hg and the ephedrine requirements were significantly higher in the IV Fentanyl group as compared with the Intrathecal Fentanyl group (P = 0.01). Also, intraoperative nausea and vomiting occurred less frequently in the Intrathecal Fentanyl group compared with the IV Fentanyl group (8 of 23 vs 17 of 25; P = 0.02).

IMPLICATIONS

Supplementation of spinal bupivacaine anesthesia for cesarean delivery with intrathecal fentanyl provides a better quality of anesthesia and is associated with a decreased incidence of side effects as compared with supplementation with the same dose of IV fentanyl.

Patient-controlled epidural fentanyl following spinal fentanyl at Caesarean section

Spinal fentanyl can improve analgesia during Caesarean section. However, there is evidence that, following its relatively short-lived analgesic effect, there is a more prolonged spinal opioid tolerance effect. The effectiveness of postoperative epidural fentanyl analgesia may therefore be reduced following the use of spinal fentanyl at operation. This randomised, double-blind study was designed to assess whether patient-controlled epidural fentanyl could produce effective analgesia following 25 microg of spinal fentanyl at operation. Patients undergoing elective Caesarean section received spinal bupivacaine combined with either fentanyl 25 microg (fentanyl group; n = 18) or normal saline (saline group; n = 18). Patient-controlled epidural fentanyl was used for postoperative analgesia. The fentanyl group used a mean of 23.4 (SD 14.5) microg x h(-1) of fentanyl, compared with 27.0 (10.8) microg x h(-1) for the saline group (p =0.41). Using a 0-100 mm visual analogue score for pain, the maximum pain score recorded at rest for the fentanyl group was median 24 [IQR 15-35] mm, compared with 15 [13-45] mm for the saline group (p = 0.41). The maximum pain score recorded on coughing for the fentanyl group was 29 [24-46] mm, compared with 27 [19-47] mm for the saline group (p = 0.44). Nine of the fentanyl group rated postoperative analgesia as excellent and nine as good, compared with 10 of the saline group who rated it as excellent and eight as good (p = 0.74). Epidural fentanyl can produce effective analgesia following the use of 25 microg spinal fentanyl at Caesarean section.

Addition of meperidine to bupivacaine for spinal anaesthesia for Caesarean section

BACKGROUND

In a prospective, randomized, double-blind, placebo-controlled trial, we investigated the effect of adding meperidine 10 mg to intrathecal bupivacaine on the duration of early postoperative analgesia in 40 patients having elective Caesarean section under spinal anaesthesia.

METHODS

Patients received intrathecal injection of 0.5% hyperbaric bupivacaine 2.0 ml plus either normal saline 0.2 ml (saline group) or 5% meperidine 0.2 ml (meperidine group). After operation, all patients were given i.v. patient-controlled analgesia using morphine.

RESULTS

The duration of effective analgesia, defined as the time from intrathecal injection to first patient-controlled analgesia demand, was greater in the meperidine group (mean 234 min, 95% confidence interval 200-269 min) compared with the saline group (mean 125 min, 95% confidence interval 111-138 min; P<0.001). The 24 h morphine requirement was similar in the two groups. The meperidine group had a greater incidence of intraoperative nausea or vomiting compared with the saline group (11 vs 3; P=0.02).

CONCLUSION

Addition of meperidine 10 mg to intrathecal bupivacaine for Caesarean section is associated with prolonged postoperative analgesia but with greater intraoperative nausea and vomiting.

Ondansetron: a selective 5-HT(3) receptor antagonist and its applications in CNS-related disorders

Ondansetron is a selective 5-hydroxytryptamine(3) (5-HT(3)) receptor antagonist that has been introduced to clinical practice as an antiemetic for cancer treatment-induced and anesthesia-related nausea and vomiting. Its use under these circumstances is both prophylactic and therapeutic. It has a superior efficacy, safety and pharmacoeconomic profile compared with other groups of antiemetics, namely antidopaminergics, antihistamines and anticholinergics. However, its place in the management of anticipatory and delayed vomiting in cancer treatment and as a rescue antiemetic in surgical patients needs to be further explored. Furthermore, recent animal and human research also reflects its possible novel application in the treatment of other disease states, such as alcoholism, cocaine addiction, opioid withdrawal syndrome, anxiety disorders, gastrointestinal motility disorders, Tourette's syndrome and pruritus. This review revisits the widespread physiological and pathological effects of 5-HT and discusses both the basic science literature and the clinical developments responsible for the conventional and novel uses of ondansetron. In addition, new discoveries relating to the effects of ondansetron on other receptors/channels and their possible therapeutic applications are presented.