Intravenous ondansetron in established postoperative emesis in children. S3A-381 Study Group

Rescue Treatment of Postoperative Nausea and Vomiting: A Systematic Review of Current Clinical Evidence

Although prophylactic antiemetics are commonly used perioperatively, an estimated 30% of surgical patients still suffer from postoperative nausea and vomiting (PONV). Very few prospective trials have studied rescue treatment of PONV after failure of prophylaxis, providing limited evidence to support clinical management. In patients who have failed PONV prophylaxis, administering a rescue antiemetic from the same drug class has been reported to be ineffective. For many antiemetics currently used in PONV rescue, significant uncertainty remains around the effective dose range, speed of onset, duration of effect, safety, and overall risk-benefit ratio. As prompt, effective PONV rescue after failure of prophylaxis is important to optimize postoperative recovery and resource utilization, we conduct this systematic review to summarize the current evidence available on the topic.

Chewing gum to treat postoperative nausea and emesis in female patients (CHEWY): rationale and design for a multicentre randomised trial

INTRODUCTION

Postoperative nausea, retching and vomiting (PONV) remains one of the most common side effects of general anaesthesia, contributing significantly to patient dissatisfaction, cost and complications. Chewing gum has potential as a novel, drug-free alternative treatment. We aim to conduct a large, definitive randomised controlled trial of the efficacy and safety of peppermint-flavoured chewing gum to treat PONV in the postanaesthesia care unit (PACU). If chewing gum is shown to be as effective as ondansetron, this trial has the potential to significantly improve outcomes for tens of millions of surgical patients around the world each year.

METHODS AND ANALYSIS

This is a prospective, multicentre, randomised controlled non-inferiority trial. 272 female patients aged ≥12 years having volatile anaesthetic-based general anaesthesia for breast or laparoscopic surgery will be randomised. Patients experiencing nausea, retching or vomiting in PACU will be randomised to 15 min of chewing gum or 4 mg intravenous ondansetron. The primary outcome (complete response) is cessation of PONV within 2 hours of administration, with no recurrence nor rescue medication requirement for 2 hours after administration.

ETHICS AND DISSEMINATION

The Chewy Trial has been approved by the Human Research Ethics Committees at all sites. Dissemination will be via international and national anaesthesia conferences, and publication in the peer-reviewed literature.

TRIAL REGISTRATION NUMBER

ACTRN12618000429257; Pre-results.

Prophylaxis of postoperative nausea and vomiting in adolescent patients: a review with emphasis on combination of fixed-dose ondansetron and transdermal scopolamine

Postoperative nausea and vomiting (PONV) is a relatively common occurrence (20–30%) that delays discharge and, if persistent, can lead to serious complications. The incidence of PONV is a function of patient characteristics, the type and duration of surgery, the type of anesthesia, and the choice of pre-, intra-, and postoperative pharmacotherapy. There are no completely effective antiemetic agents for this condition, but recommendations for treatment strategies are separately available for pediatric and adult patients. Left unclear is whether adolescents should be guided by the pediatric or the adult recommendations. We review the developmental physiology of the relevant physiological factors (absorption, distribution, metabolism, and elimination). We also review the clinical evidence regarding the safety and efficacy of a fixed-dose combination of ondansetron (4 mg, i.v.) and transdermal scopolamine (1.5 mg).

[Nausea and vomiting in the postoperative phase. Expert- and evidence-based recommendations for prophylaxis and therapy]

There are no consensus guidelines for the management of postoperative nausea and vomiting (PONV) in German speaking countries. This meeting was intended to develop such guidelines on which individual health care facilities can derive their specific standard operating procedures (SOPs). Anesthesiologists reviewed published literature on key topics which were subsequently discussed during two meetings. It was emphasized that recommendations were based on the best available evidence. The clinical relevance of individual risk factors should be viewed with caution since even well proven risk factors, such as the history of PONV, do not allow the identification of patients at risk for PONV with a satisfactory sensitivity or specificity. A more useful approach is the use of simplified risk scores which consider the presence of several risk factors simultaneously. Most individual antiemetic interventions for the prevention of PONV have comparable efficacy with a relative risk reduction of about 30%. This appears to be true for total intravenous anesthesia (TIVA) as well as for dexamethasone and other antiemetics; assuming a sufficiently high, adequate and equipotent dosage which should be weight-adjusted in children. As the relative risk reduction is context independent and similar between the interventions, the absolute risk reduction of prophylactic interventions is mainly dependent on the patient's individual baseline risk. Prophylaxis is thus rarely warranted in patients at low risk, generally needed in patients with a moderate risk and should include a multimodal approach in patients at high risk for PONV. Therapeutic interventions of PONV should be administered promptly using an antiemetic which has not been used before. The group suggests algorithms where prophylactic interventions are mainly dependent on the patient's risk for PONV. These algorithms should provide evidence-based guidelines allowing the development of SOPs/policies which take local circumstances into account.

Management of postoperative nausea and vomiting in children

Postoperative nausea and vomiting (PONV) continues to be a frequent and important cause of morbidity in children. Postoperative vomiting (POV) is more commonly studied in children than postoperative nausea because of a child's inability to effectively express distress after experiencing nausea. POV is problematic in children and is one of the leading postoperative complaints from parents and the leading cause of readmission to the hospital. POV occurs twice as frequently in children as in adults, increasing until puberty and then decreasing to adult incidence rates. Gender differences are not seen before puberty. POV remains a main cause of morbidity in children because severe vomiting can be associated with dehydration, postoperative bleeding, pulmonary aspiration, and wound dehiscence. While children have an increased potential for dehydration and the resulting physiologic impairments, other associated results such as a delay in hospital discharge or an overnight or longer hospital admission also must be considered. The two most common emetogenic surgical procedures evaluated in children are strabismus repair and adenotonsillectomy. The approach to the management of PONV and POV in children is similar to that in adults. However, as the rate of POV is more frequent in children than in adults, more children are candidates for antiemetic prophylaxis. The management approach is multifactorial and involves proper preoperative preparation, risk stratification, rational selection of antiemetic prophylaxis, choice of anesthesia technique, and a plan for postoperative antiemetic therapy. It is important to identify children at moderate-to-high risk for POV as prophylactic antiemetic therapy is useful in these children. Antiemetics of choice for POV in children include dexamethasone, dimenhydrinate, perphenazine, ondansetron, dolasetron, granisetron, and tropisetron. The serotonin (5-hydroxytryptamine; 5-HT(3)) antagonists are the antiemetic drugs of first choice for POV prophylaxis in children because as a group they have greater efficacy for preventing vomiting than nausea. The 5-HT(3) antagonists can be effectively combined with dexamethasone with an increase in efficacy. If possible, regional anesthesia should be considered. For those undergoing general anesthesia, the baseline POV risk should be reduced. Children at moderate-to-high PONV risk should receive combination therapy with two or three prophylactic antiemetics from different antiemetic drug classes. Reference to and the use of PONV guidelines and management algorithms help improve cost-effective postoperative care.

Management of postoperative vomiting in pediatric patients

PURPOSE OF REVIEW

Postoperative vomiting remains a common complication of general anesthesia and occurs more frequently in children than adults. Prophylactic antiemetics have limited efficacy and have a potential for side effects. The new 5 HT3 antagonists are effective but expensive, while the older less expensive drugs such as droperidol have come under disrepute because of the potential for serious, life-threatening, cardiac arrhythmias. This review examines the literature to aid practicing anesthesiologists in the choice of patient who will benefit from prophylactic antiemetics.

RECENT FINDINGS

In this review we discuss the factors associated with postoperative vomiting that are and are not under the control of the anesthesiologist. The Consensus Panel recommendations for reducing the risks of postoperative vomiting and for the rational use of prophylactic antiemetics in selected cases are reviewed. The controversy over the 'black box warning' on the use of droperidol is discussed. Finally, the evidence supports the importance of choosing a drug from another class for rescue therapy when prophylaxis with one drug has failed.

SUMMARY

Anesthesiologists should practice evidence-based medicine in reducing the common anesthetic complication of postoperative vomiting by an individualized approach that balances the choice of drugs with the expected risk of postoperative vomiting for cost-effective management.

Systematic review on the recurrence of postoperative nausea and vomiting after a first episode in the recovery room - implications for the treatment of PONV and related clinical trials

Background

Despite the presence of a plethora of publications on the prevention of postoperative nausea and vomiting (PONV) only little is known how to treat established symptoms. Besides the high effort of performing these efficacy trials (much more patients must give their consent than are actually included in a study) and ethical concerns, little is known about the rate of re-occurring PONV/vomiting after placebo. As a consequence investigators will have difficulties defining a clinically relevant effect for the new treatment which is crucial for any planning. A quantitative systematic review was performed in order to provide more reliable estimates of the incidence of re-occurring PONV/vomiting after placebo and to help investigators defining a clinically relevant treatment effect.

Methods

A systematic search of the literature was performed using an extended search strategy of a previous review. Data on the recurrence of PONV (any nausea or emetic symptom) and vomiting (retching or vomiting) was extracted from published reports treating PONV with placebo and unpublished results from two observational trials where no treatment was given. A nonlinear random effects model was used to calculate estimates of the recurrence of symptoms and their 95%-confidence intervals (95%-CI).

Results

A total of 29 trials (including the unpublished data) were eligible for the calculations. Depending on the length of observation after administering placebo or no treatment the recurrence rate of PONV was between 65% (95%-CI: 53%...75%) and 84% (95%-CI: 73%...91%) and that of vomiting was between 65% (95%-CI: 44%...81%) and 78% (95%-CI: 59%...90%).

Conclusion

Almost all trials showed a considerable and consistently high rate of recurrence of emetic symptoms after placebo highlighting the need for a consequent antiemetic treatment. Future (placebo) controlled efficacy trials may use the presented empirical estimates for defining clinically relevant effects and for statistical power considerations.

A Double-Blind Comparison of Intravenous Ondansetron and Placebo for Preventing Postoperative Emesis in 1- to 24-Month-Old Pediatric Patients After Surgery Under General Anesthesia

We assessed the efficacy and safety of ondansetron (0.1 mg/kg IV) prophylactically administered before surgery for prevention of postoperative vomiting (POV) in a double-blind, placebo-controlled study of 670 pediatric patients, 1- to 24-mo-old, undergoing elective surgery under general anesthesia. The study enrolled 335 children in each treatment group (ondansetron versus placebo). Significantly fewer children treated with ondansetron exhibited emesis or discontinued the study prematurely after surgery (ondansetron, 11%; placebo, 28%; odds ratio = 0.33; P < 0.0001). The number required to treat prophylactically with ondansetron to prevent POV was approximately six. Ondansetron treatment also resulted in fewer patients requiring rescue medication or assumed to have had rescue upon early discontinuation from the study during the postoperative period (ondansetron, 5%; placebo, 10%) and less emesis (0 of 6) after rescue medication when compared with placebo (7 of 21). The incidence of POV and other antiemetic effects of ondansetron were similar in children aged 1-12 mo and 13-24 mo and in children prospectively expected or not expected to require opioids as part of their anesthetic or analgesic management. Ondansetron was well tolerated; the incidence of adverse events considered possibly related to study drug was similar between treatment groups (ondansetron, 1.8%; placebo, 1.5%).

IMPLICATIONS

This prospective, randomized, double-blind, placebo-controlled study establishes the efficacy and tolerability of IV ondansetron (0.1 mg/kg) in the prevention of postoperative emesis in 1- to 24-mo-old pediatric patients undergoing elective surgery under general anesthesia.

Benefits and risks of newer treatments for chemotherapy-induced and postoperative nausea and vomiting

Nausea and vomiting are common adverse effects of chemotherapy, radiation therapy, anaesthesia and surgery. The incidence of chemotherapy-induced nausea and vomiting (CINV) is estimated to vary from 30 to 90%, depending on the type of chemotherapeutic agent used. Radiation-induced emesis varies with anatomical site radiated but is estimated to have an overall incidence of approximately 40%. The incidence of postoperative nausea and vomiting (PONV) depends on the type of anaesthesia and surgery, but overall is estimated to be 20-30%. Evidence-based medicine and meta-analysis have been used to direct medical therapy to help determine equivalence, optimal dose, timing, safety and efficacy of antiemetic medications. Concepts such as the number needed to treat and number needed to harm are helpful to guide the clinician regarding the benefits and risks of a particular treatment. The serotonin 5-HT(3) receptor antagonists ondansetron, granisetron, tropisetron and dolasetron have been important additions to the antiemetic armamentarium. The 5-HT(3) receptor antagonists are similar in chemical structure, efficacy and adverse effect profile. They appear to have no important differences among themselves in clinical outcomes for CINV and PONV. Headache, dizziness, constipation and diarrhoea are their most common adverse effects, and when they occur they are usually mild and easily managed. Haemodynamic changes and extrapyramidal adverse effects are uncommon. ECG changes such as prolonged corrected QT (QTc) interval are infrequent, dose-related and overall judged to be clinically insignificant. As most studies with the 5-HT(3) antagonists have been conducted on relatively healthy patients, caution should be exercised when these drugs are used in susceptible patients with co-morbidities. The clinician must weigh the benefit of administering an antiemetic for CINV or PONV against the risk of occurrence of an adverse event.

Management of postoperative nausea and vomiting in ambulatory surgery

The management of PONV has improved significantly over the years but remains a frequent occurrence in postoperative patients. Evaluation of individual patient risk and the consideration for prophylactic antiemetic in high-risk populations should reduce these unpleasant symptoms and help direct appropriate clinical strategies. Treatment following failure of prophylactic antiemetic therapy requires knowledge of previously used antiemetics and the time of their administration.

Ondansetron: a review of its use as an antiemetic in children

Ondansetron, a selective serotonin (5-hydroxytryptamine; 5-HT) 5-HT3 receptor antagonist, is an antiemetic agent available for use in adults and children. In children receiving ondansetron (multiple 5 mg/m2 or 0.15 mg/kg intravenous and/or oral doses) in addition to chemotherapy in 2 large (n > 100) non-comparative analyses, < or =2 emetic episodes were observed in 33 and 40% of cisplatin recipients, 48 and 68% of ifosfamide recipients, and 70 and 72% of patients receiving other chemotherapeutic regimens. In comparative trials, ondansetron was significantly more effective at reducing nausea and vomiting than metoclopramide or chlorpromazine (both combined with dexamethasone), although the incidence of delayed symptoms were similar between children receiving ondansetron and metoclopramide. In addition, dexamethasone significantly improved the antiemetic efficacy of ondansetron in 1 randomised trial. When used in children undergoing conditioning therapy (including total body irradiation) prior to bone marrow transplantation, ondansetron was significantly better at controlling nausea and vomiting than combined perphenazine and diphenhydramine therapy. In dose-ranging and large placebo-controlled trials, intravenous (0.075 to 0.15 mg/kg) or oral (0.1 mg/kg) ondansetron was significantly more effective than placebo in preventing emesis in children undergoing surgery associated with a high risk of postoperative nausea and vomiting (PONV) including tonsillectomy or strabismus repair. In comparative studies, intravenous administration of ondansetron 0.1 to 0.15 mg/kg was significantly superior to droperidol 0.02 to 0.075 mg/kg or metoclopramide 0.2 to 0.25 mg/kg in preventing emesis in children undergoing various surgical procedures. In comparison with other antiemetics, including prochlorperazine and dimenhydrinate, ondansetron generally showed greater prophylactic antiemetic efficacy. Ondansetron combined with dexamethasone was significantly more effective than ondansetron or dexamethasone alone, as was the combination of ondansetron with a propofol-based anaesthetic compared with either agent alone. Ondansetron is generally well tolerated in children, rarely necessitating treatment withdrawal. The most frequently reported adverse events were mild to moderate headache, constipation and diarrhoea in patients receiving chemotherapy. Wound problems, anxiety, headache, drowsiness and pyrexia were reported most frequently in patients postsurgery.

CONCLUSIONS

Ondansetron has shown good efficacy in the prevention of acute nausea and vomiting in children receiving moderately or highly emetogenic chemotherapy and/or irradiation, particularly when combined with dexamethasone. In the chemotherapy setting, ondansetron is significantly better than metoclopramide and chlorpromazine and has a more favourable tolerability profile. In children undergoing surgery, ondansetron demonstrated superior prophylactic antiemetic efficacy compared with placebo, droperidol and metoclopramide, and was relatively free of adverse events. Ondansetron is thus an effective first-line antiemetic in children undergoing chemotherapy, radiotherapy and surgery.

Treatment of established postoperative nausea and vomiting: a quantitative systematic review

BACKGROUND: The relative efficacy of antiemetics for the treatment of postoperative nausea and vomiting (PONV) is poorly understood. METHODS: Systematic search (MEDLINE, Embase, Cochrane Library, bibliographies, any language, to 8.2000) for randomised comparisons of antiemetics with any comparator for the treatment of established PONV. Dichotomous data on prevention of further nausea and vomiting, and on side effects were combined using a fixed effect model. RESULTS: In seven trials (1,267 patients), 11 different antiemetics were tested without placebos; these data were not further analysed. Eighteen trials (3,809) had placebo controls. Dolasetron 12.5-100 mg, granisetron 0.1-3 mg, tropisetron 0.5-5 mg, and ondansetron 1-8 mg prevented further vomiting with little evidence of dose-responsiveness; with all regimens, absolute risk reductions compared with placebo were 20%-30%. The anti-nausea effect was less pronounced. Headache was dose-dependent. Results on propofol were contradictory. The NK1 antagonist GR205171, isopropyl alcohol vapor, metoclopramide, domperidone, and midazolam were tested in one trial each with a limited number of patients. CONCLUSIONS: Of 100 vomiting surgical patients receiving a 5-HT3 receptor antagonist, 20 to 30 will stop vomiting who would not have done so had they received a placebo; less will profit from the anti-nausea effect. There is a lack of evidence for a clinically relevant dose-response; minimal effective doses may be used. There is a discrepancy between the plethora of trials on prevention of PONV and the paucity of trials on treatment of established symptoms. Valid data on the therapeutic efficacy of classic antiemetics, which have been used for decades, are needed.

Combination therapy for postoperative nausea and vomiting - a more effective prophylaxis?

The problem of postoperative nausea and vomiting (PONV) remains far from being resolved. Despite the introduction of new classes of antiemetics and a vast amount of published research, there is a general impression that there has been little progress in this area. The multifactorial etiology of PONV might be better addressed using a combination of drugs acting at different receptor sites. This approach of balanced antiemesis may be the answer towards achieving a significant improvement in the management of PONV. This article will cover the different strategies used to prevent PONV with particular emphasis on combination antiemetics. A review of the currently available methods to manage PONV as well as the physiological and pharmacological basis of combination therapy is presented.

Prevention and treatment of postoperative nausea and vomiting

Pain, nausea and vomiting are frequently listed by patients as their most important perioperative concerns. With the change in emphasis from an inpatient to outpatient hospital and office-based medical/surgical environment, there has been increased interest in the 'big little problem' of postoperative nausea and vomiting (PONV). Currently, the overall incidence of PONV is estimated to be 25 to 30%, with severe, intractable PONV estimated to occur in approximately 0.18% of all patients undergoing surgery. PONV can lead to delayed postanaesthesia care unit (PACU) recovery room discharge and unanticipated hospital admission, thereby increasing medical costs. The aetiology and consequences of PONV are complex and multifactorial, with patient-, medical- and surgery-related factors. A thorough understanding of these factors, as well as the neuropharmacology of multiple emetic receptors [dopaminergic, muscarinic, cholinergic, opioid, histamine, serotonin (5-hydroxy-tryptamine; 5-HT)] and physiology [cranial nerves VIII (acoustic-vestibular), IX (glossopharyngeal) and X (vagus), gastrointestinal reflex] relating to PONV are necessary to most effectively manage PONV. Commonly used older, traditional antiemetics for PONV include the anticholinergics (scopolamine), phenothiazines (promethazine), antihistamines (diphenhydramine), butyrophenones (droperidol) and benzamides (metoclopramide). These antiemetics have adverse effects such as dry mouth, sedation, hypotension, extrapyramidal symptoms, dystonic effects and restlessness. The newest class of antiemetics used for the prevention and treatment of PONV are the serotonin receptor antagonists (ondansetron, granisetron, tropisetron, dolasetron). These antiemetics do not have the adverse effects of the older, traditional antiemetics. Headache and dizziness are the main adverse effects of the serotonin receptor antagonists in the dosages used for PONV. The serotonin receptor antagonists have improved antiemetic effectiveness but are not as completely efficacious for PONV as they are for chemotherapy-induced nausea and vomiting. Older, traditional antiemetics (such as droperidol) compare favourably with the serotonin receptor antagonists regarding efficacy for PONV prevention. Combination antiemetic therapy improves efficacy for PONV prevention and treatment. In the difficult-to-treat PONV patient (as in the chemotherapy patient), suppression of numerous emetogenic peripheral stimuli and central neuroemetic receptors may be necessary. This multimodal PONV management approach includes use of: (i) multiple different antiemetic medications (double or triple combination antiemetic therapy acting at different neuroreceptor sites); (ii) less emetogenic anaesthesia techniques; (iii) adequate intravenous hydration; and (iv) adequate pain control.

Fast-track concept for ambulatory anesthesia

Fast-tracking in the ambulatory setting refers to the ability to transfer suitably recovered patients from the operating room directly to the Phase II (step-down) recovery area, bypassing the postanesthesia care unit. This article describes the concept of fast-tracking after ambulatory surgery and reviews anesthetic techniques that have helped to facilitate this process. The prevention and management of postoperative pain and nausea are also discussed.

Ondansetron in the prophylaxis of postoperative vomiting: a meta-analysis

STUDY OBJECTIVES

To assess the efficacy of ondansetron and the incidence of headache when used as prophylaxis for postoperative vomiting.

DATA SOURCES

Studies were identified using MEDLINE (January 1990 to July 1997) with the key words: "vomiting," "ondansetron," and "surgery" and/or "anesthesia."

STUDY SELECTION

All prospectively randomized trials in which ondansetron and placebo had been administered for prevention of postoperative vomiting.

DATA EXTRACTION

Data on patient numbers, gender and ages, drug dosage, outcomes (incidence of vomiting and incidence of headache), time of outcome (up to 8 hrs or up to 48 hrs postoperatively), and baseline risk for vomiting according to type of surgical intervention were extracted.

MAIN RESULTS

48 trials involving 12,078 patients (10,390 adults and 1688 children) met the selection criteria. No evidence was found that the drug became more effective at doses larger than 4 mg. The dose of 8 mg was not statistically demonstrated to be superior (p = 0.558), while that of 1 mg was barely effective. The meta-analysis indicated that when the incidence of vomiting is elevated (e.g., the combined average of the placebo groups of 48%), on the statistical (i.e., hypothetical) grounds of six patients being treated with 4 mg of ondansetron, one will not vomit due to the treatment and, of the rest, two patients would have vomited despite the treatment and three patients would not have vomited anyway. The overall incidence of headache was 7.05% in ondansetron groups versus 6.16% in placebo groups.

CONCLUSIONS

While ondansetron is an effective antiemetic with minimal adverse effects, the data obtained on the numbers needed to be treated calculation for prophylaxis of postoperative vomiting should be considered in future cost-effective strategies of postoperative management.