The antiemetic efficacy of droperidol added to morphine patient-controlled analgesia: a randomized, controlled, multicenter dose-finding study

Quetiapine-Related Deaths: In Search of a Surrogate Endpoint

Quetiapine is a second-generation antipsychotic drug available for two and half decades. Due to increased misuse, prescription outside the approved indications, and availability on the black market, it is being encountered in medicolegal autopsies more frequently. For instance, it has been linked to increased mortality rates, most likely due to its adverse effects on the cardiovascular system. Its pharmacokinetic features and significant postmortem redistribution challenge traditional sampling in forensic toxicology. Therefore, a systematic literature review was performed, inclusive of PubMed, the Web of Science-core collection, and the Scopus databases; articles were screened for the terms "quetiapine", "death", and "autopsy" to reevaluate each matrix used as a surrogate endpoint in the forensic toxicology of quetiapine-related deaths. Ultimately, this review considers the results of five studies that were well presented (more than two matrices, data available for all analyses, for instance). The highest quetiapine concentrations were usually measured in the liver tissue. As interpreted by their authors, the results of the considered studies showed a strong correlation between some matrices, but, unfortunately, the studies presented models with poor goodness of fit. The distribution of quetiapine in distinct body compartments/tissues showed no statistically significant relationship with the length of the postmortem interval. Furthermore, this study did not confirm the anecdotal correlation of peripheral blood concentrations with skeletal muscle concentrations. Otherwise, there was no consistency regarding selecting an endpoint for analysis.

Quetiapine and other antipsychotics combined with opioids in legal autopsy cases: A random finding or cause of fatal outcome?

Opioid poisoning is a frequent cause of death in drug addicts and occurs with opioid treatment. Quetiapine is often found in forensic autopsies and may increase the risk of fatal opioid poisoning by enhancing sedation, respiratory depression, hypotension and QT prolongation. We systematically searched for studies of acute toxicity of quetiapine or other antipsychotics combined with morphine or methadone. Case reports describing toxicity of quetiapine combined with morphine or methadone were also included. We retrieved one human study that observed pharmacokinetic interaction between quetiapine and methadone, and 16 other human studies. Fourteen investigated the combination of droperidol and morphine in treatment doses, and some indicated an additive sedative effect. Five animal studies with acepromazine in combination with morphine or methadone were located and indicated an additive effect on sedation and hypotension. Six forensic case reports in which death could have been caused solely by quetiapine, the opioid, or other drugs were found. Thus, acute toxicity of quetiapine combined with morphine or methadone has not been studied. Because of quetiapine's effects on alpha-adrenoceptors, muscarinic and histamine receptors, human ether-a-go-go-channels and methadone kinetics, we suggest further research to clarify if the indicated additive effects of opioids and droperidol or acepromazine are also true for quetiapine.

Drugs for preventing postoperative nausea and vomiting in adults after general anaesthesia: a network meta-analysis

BACKGROUND

Postoperative nausea and vomiting (PONV) is a common adverse effect of anaesthesia and surgery. Up to 80% of patients may be affected. These outcomes are a major cause of patient dissatisfaction and may lead to prolonged hospital stay and higher costs of care along with more severe complications. Many antiemetic drugs are available for prophylaxis. They have various mechanisms of action and side effects, but there is still uncertainty about which drugs are most effective with the fewest side effects.

OBJECTIVES

• To compare the efficacy and safety of different prophylactic pharmacologic interventions (antiemetic drugs) against no treatment, against placebo, or against each other (as monotherapy or combination prophylaxis) for prevention of postoperative nausea and vomiting in adults undergoing any type of surgery under general anaesthesia • To generate a clinically useful ranking of antiemetic drugs (monotherapy and combination prophylaxis) based on efficacy and safety • To identify the best dose or dose range of antiemetic drugs in terms of efficacy and safety SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), ClinicalTrials.gov, and reference lists of relevant systematic reviews. The first search was performed in November 2017 and was updated in April 2020. In the update of the search, 39 eligible studies were found that were not included in the analysis (listed as awaiting classification).

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing effectiveness or side effects of single antiemetic drugs in any dose or combination against each other or against an inactive control in adults undergoing any type of surgery under general anaesthesia. All antiemetic drugs belonged to one of the following substance classes: 5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, corticosteroids, antihistamines, and anticholinergics. No language restrictions were applied. Abstract publications were excluded.

DATA COLLECTION AND ANALYSIS

A review team of 11 authors independently assessed trials for inclusion and risk of bias and subsequently extracted data. We performed pair-wise meta-analyses for drugs of direct interest (amisulpride, aprepitant, casopitant, dexamethasone, dimenhydrinate, dolasetron, droperidol, fosaprepitant, granisetron, haloperidol, meclizine, methylprednisolone, metoclopramide, ondansetron, palonosetron, perphenazine, promethazine, ramosetron, rolapitant, scopolamine, and tropisetron) compared to placebo (inactive control). We performed network meta-analyses (NMAs) to estimate the relative effects and ranking (with placebo as reference) of all available single drugs and combinations. Primary outcomes were vomiting within 24 hours postoperatively, serious adverse events (SAEs), and any adverse event (AE). Secondary outcomes were drug class-specific side effects (e.g. headache), mortality, early and late vomiting, nausea, and complete response. We performed subgroup network meta-analysis with dose of drugs as a moderator variable using dose ranges based on previous consensus recommendations. We assessed certainty of evidence of NMA treatment effects for all primary outcomes and drug class-specific side effects according to GRADE (CINeMA, Confidence in Network Meta-Analysis). We restricted GRADE assessment to single drugs of direct interest compared to placebo.

MAIN RESULTS

We included 585 studies (97,516 randomized participants). Most of these studies were small (median sample size of 100); they were published between 1965 and 2017 and were primarily conducted in Asia (51%), Europe (25%), and North America (16%). Mean age of the overall population was 42 years. Most participants were women (83%), had American Society of Anesthesiologists (ASA) physical status I and II (70%), received perioperative opioids (88%), and underwent gynaecologic (32%) or gastrointestinal surgery (19%) under general anaesthesia using volatile anaesthetics (88%). In this review, 44 single drugs and 51 drug combinations were compared. Most studies investigated only single drugs (72%) and included an inactive control arm (66%). The three most investigated single drugs in this review were ondansetron (246 studies), dexamethasone (120 studies), and droperidol (97 studies). Almost all studies (89%) reported at least one efficacy outcome relevant for this review. However, only 56% reported at least one relevant safety outcome. Altogether, 157 studies (27%) were assessed as having overall low risk of bias, 101 studies (17%) overall high risk of bias, and 327 studies (56%) overall unclear risk of bias. Vomiting within 24 hours postoperatively Relative effects from NMA for vomiting within 24 hours (282 RCTs, 50,812 participants, 28 single drugs, and 36 drug combinations) suggest that 29 out of 36 drug combinations and 10 out of 28 single drugs showed a clinically important benefit (defined as the upper end of the 95% confidence interval (CI) below a risk ratio (RR) of 0.8) compared to placebo. Combinations of drugs were generally more effective than single drugs in preventing vomiting. However, single NK₁ receptor antagonists showed treatment effects similar to most of the drug combinations. High-certainty evidence suggests that the following single drugs reduce vomiting (ordered by decreasing efficacy): aprepitant (RR 0.26, 95% CI 0.18 to 0.38, high certainty, rank 3/28 of single drugs); ramosetron (RR 0.44, 95% CI 0.32 to 0.59, high certainty, rank 5/28); granisetron (RR 0.45, 95% CI 0.38 to 0.54, high certainty, rank 6/28); dexamethasone (RR 0.51, 95% CI 0.44 to 0.57, high certainty, rank 8/28); and ondansetron (RR 0.55, 95% CI 0.51 to 0.60, high certainty, rank 13/28). Moderate-certainty evidence suggests that the following single drugs probably reduce vomiting: fosaprepitant (RR 0.06, 95% CI 0.02 to 0.21, moderate certainty, rank 1/28) and droperidol (RR 0.61, 95% CI 0.54 to 0.69, moderate certainty, rank 20/28). Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol showed clinically important benefit, but low doses showed no clinically important benefit. Aprepitant was used mainly at high doses, ramosetron at recommended doses, and fosaprepitant at doses of 150 mg (with no dose recommendation available). Frequency of SAEs Twenty-eight RCTs were included in the NMA for SAEs (10,766 participants, 13 single drugs, and eight drug combinations). The certainty of evidence for SAEs when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to low. Droperidol (RR 0.88, 95% CI 0.08 to 9.71, low certainty, rank 6/13) may reduce SAEs. We are uncertain about the effects of aprepitant (RR 1.39, 95% CI 0.26 to 7.36, very low certainty, rank 11/13), ramosetron (RR 0.89, 95% CI 0.05 to 15.74, very low certainty, rank 7/13), granisetron (RR 1.21, 95% CI 0.11 to 13.15, very low certainty, rank 10/13), dexamethasone (RR 1.16, 95% CI 0.28 to 4.85, very low certainty, rank 9/13), and ondansetron (RR 1.62, 95% CI 0.32 to 8.10, very low certainty, rank 12/13). No studies reporting SAEs were available for fosaprepitant. Frequency of any AE Sixty-one RCTs were included in the NMA for any AE (19,423 participants, 15 single drugs, and 11 drug combinations). The certainty of evidence for any AE when using one of the best and most reliable anti-vomiting drugs (aprepitant, ramosetron, granisetron, dexamethasone, ondansetron, and droperidol compared to placebo) ranged from very low to moderate. Granisetron (RR 0.92, 95% CI 0.80 to 1.05, moderate certainty, rank 7/15) probably has no or little effect on any AE. Dexamethasone (RR 0.77, 95% CI 0.55 to 1.08, low certainty, rank 2/15) and droperidol (RR 0.89, 95% CI 0.81 to 0.98, low certainty, rank 6/15) may reduce any AE. Ondansetron (RR 0.95, 95% CI 0.88 to 1.01, low certainty, rank 9/15) may have little or no effect on any AE. We are uncertain about the effects of aprepitant (RR 0.87, 95% CI 0.78 to 0.97, very low certainty, rank 3/15) and ramosetron (RR 1.00, 95% CI 0.65 to 1.54, very low certainty, rank 11/15) on any AE. No studies reporting any AE were available for fosaprepitant. Class-specific side effects For class-specific side effects (headache, constipation, wound infection, extrapyramidal symptoms, sedation, arrhythmia, and QT prolongation) of relevant substances, the certainty of evidence for the best and most reliable anti-vomiting drugs mostly ranged from very low to low. Exceptions were that ondansetron probably increases headache (RR 1.16, 95% CI 1.06 to 1.28, moderate certainty, rank 18/23) and probably reduces sedation (RR 0.87, 95% CI 0.79 to 0.96, moderate certainty, rank 5/24) compared to placebo. The latter effect is limited to recommended and high doses of ondansetron. Droperidol probably reduces headache (RR 0.76, 95% CI 0.67 to 0.86, moderate certainty, rank 5/23) compared to placebo. We have high-certainty evidence that dexamethasone (RR 1.00, 95% CI 0.91 to 1.09, high certainty, rank 16/24) has no effect on sedation compared to placebo. No studies assessed substance class-specific side effects for fosaprepitant. Direction and magnitude of network effect estimates together with level of evidence certainty are graphically summarized for all pre-defined GRADE-relevant outcomes and all drugs of direct interest compared to placebo in http://doi.org/10.5281/zenodo.4066353.

AUTHORS' CONCLUSIONS

We found high-certainty evidence that five single drugs (aprepitant, ramosetron, granisetron, dexamethasone, and ondansetron) reduce vomiting, and moderate-certainty evidence that two other single drugs (fosaprepitant and droperidol) probably reduce vomiting, compared to placebo. Four of the six substance classes (5-HT₃ receptor antagonists, D₂ receptor antagonists, NK₁ receptor antagonists, and corticosteroids) were thus represented by at least one drug with important benefit for prevention of vomiting. Combinations of drugs were generally more effective than the corresponding single drugs in preventing vomiting. NK₁ receptor antagonists were the most effective drug class and had comparable efficacy to most of the drug combinations. 5-HT₃ receptor antagonists were the best studied substance class. For most of the single drugs of direct interest, we found only very low to low certainty evidence for safety outcomes such as occurrence of SAEs, any AE, and substance class-specific side effects. Recommended and high doses of granisetron, dexamethasone, ondansetron, and droperidol were more effective than low doses for prevention of vomiting. Dose dependency of side effects was rarely found due to the limited number of studies, except for the less sedating effect of recommended and high doses of ondansetron. The results of the review are transferable mainly to patients at higher risk of nausea and vomiting (i.e. healthy women undergoing inhalational anaesthesia and receiving perioperative opioids). Overall study quality was limited, but certainty assessments of effect estimates consider this limitation. No further efficacy studies are needed as there is evidence of moderate to high certainty for seven single drugs with relevant benefit for prevention of vomiting. However, additional studies are needed to investigate potential side effects of these drugs and to examine higher-risk patient populations (e.g. individuals with diabetes and heart disease).

Effect of multimodal intervention on postoperative nausea and vomiting in patients undergoing gynecological laparoscopy

OBJECTIVE

Postoperative nausea and vomiting (PONV) is a common complication in patients undergoing gynecological laparoscopic surgery, and achieving good results is difficult with a single antiemetic method. This study investigated whether multimodal intervention can reduce PONV in patients undergoing gynecological laparoscopic surgery.

METHODS

A total of 153 patients who underwent gynecological laparoscopic surgery were randomized into the control group and multimodal group. Patients in the multimodal group received dexmedetomidine 1 µg/kg intravenously 15 minutes before induction of anesthesia. A bilateral transversus abdominis plane block was performed with 0.375% ropivacaine 30 mL after induction of anesthesia. Scores of postoperative nausea and vomiting, the visual analog scale, and the Bruggemann comfort scale (BCS) were assessed 24 hours postoperatively.

RESULTS

Nausea and vomiting scores were significantly lower at 2, 6, and 24 hours in the multimodal group compared with the control group. BCS scores were significantly higher at 0 to 24 hours in the multimodal group compared with the control group.

CONCLUSIONS

Multimodal intervention improves PONV and increases patients' comfort. The multimodal approach can also enhance recovery after gynecological laparoscopic surgery.

Addition of droperidol to prophylactic ondansetron and dexamethasone in children at high risk for postoperative vomiting. A randomized, controlled, double-blind study

Background

: The combination of dexamethasone (DEX), ondansetron (OND) and droperidol (DRO) is efficacious in preventing postoperative nausea and vomiting in adults, but has not been well assessed in children.

Methods

: Children undergoing elective surgery under general anaesthesia and considered at high risk for postoperative vomiting (POV) were randomly assigned to receive a combination of DEX, OND and placebo (Group A) or a combination of DEX, OND and DRO (Group B). The primary outcome was the incidence of POV during the first 24 hours after surgery. We hypothesized that the addition of DRO to the standard antiemetic prophylaxis would provide a further 15% reduction in the residual risk for POV. The secondary outcome considered was any adverse event occurring during the study.

Results

: One hundred and fifty-three children, aged three to 16 years, were randomized to Group A and 162 to Group B. The overall incidence of POV did not differ significantly between the two groups, with 16 patients in Group A (10.5%) and 18 in Group B (11.1%) presenting with one or more episodes of POV, P =0.86. Fewer patients presented with adverse events in Group A (2%) compared with Group B (8%), P =0.01. Drowsiness and headache were the principal adverse events reported.

Conclusions

: The addition of DRO to a combination of OND and DEX did not decrease POV frequency below that obtained with the two-drug combination in children at high risk of POV, but increased the risk of drowsiness. The combination of DEX and OND should be recommended in children with a high risk of POV.

Clinical trial registration.

NCT01739985.

An Audit of Changes in Outcomes of Acute Pain Service: Evolution Over the Last 2 Decades

Acute pain services (APS) have evolved over time. Strategies nowadays emphasize multimodal analgesic regimes using a combination of nonopioid adjuvant analgesic drugs, peripheral nerve blocks, and local anaesthetic wound infiltration where appropriate. APS should be assessed over time to evaluate changes in outcomes which form the basis for future development. In this audit, data of patients under APS care in Queen Mary hospital, Hong Kong, between 2009 and 2012 were analyzed and compared with data from a previous audit between 1992 and 1995. The use of patient-controlled analgesia (PCA) was increased (from 69.3% to 86.5%, P < 0.001), while the use of epidural analgesia reduced (from 25.3% to 8.3%, P < 0.001) significantly. Although postoperative pain scores did not improve, PCA opioid consumption and the incidence of analgesia-related side effects were significantly less (all P < 0.001). More patients graded their postoperative analgesic techniques used as good when the results from these 2 audit periods were compared (P < 0.001 and P = 0.001 for PCA and epidural analgesia, respectively). In conclusion, there has been a change in analgesic management techniques, but there has been no improvement in overall pain relief. While changes over time have led to improvement in important parameters such as the incidence of side effects and patient satisfaction, further and continuous efforts and improvements are warrant to reduce acute pain relief and suffering of the patients after the surgery.

Consensus guidelines for the management of postoperative nausea and vomiting

The present guidelines are the most recent data on postoperative nausea and vomiting (PONV) and an update on the 2 previous sets of guidelines published in 2003 and 2007. These guidelines were compiled by a multidisciplinary international panel of individuals with interest and expertise in PONV under the auspices of the Society for Ambulatory Anesthesia. The panel members critically and systematically evaluated the current medical literature on PONV to provide an evidence-based reference tool for the management of adults and children who are undergoing surgery and are at increased risk for PONV. These guidelines identify patients at risk for PONV in adults and children; recommend approaches for reducing baseline risks for PONV; identify the most effective antiemetic single therapy and combination therapy regimens for PONV prophylaxis, including nonpharmacologic approaches; recommend strategies for treatment of PONV when it occurs; provide an algorithm for the management of individuals at increased risk for PONV as well as steps to ensure PONV prevention and treatment are implemented in the clinical setting.

Prophylaxis of intra- and postoperative nausea and vomiting in patients during cesarean section in spinal anesthesia

Background

This paper describes a randomized prospective study conducted in 308 patients undergoing caesarean section in spinal anaesthesia at a single hospital between 2010 and 2012 to find a suitable anti-emetic strategy for these patients.

Material/Methods

Spinal anesthesia was performed in left prone position, at L3/L4 with hyperbaric 0.5% Bupivacaine according to a cc/cm body height ratio. There were no opioids given peri-operatively. The patients received either no prophylaxis (Group I) or tropisetron and metoclopramide (Group II) or dimenhydrinate and dexamethasone (Group III), or tropisetron as a single medication (Group IV). The primary outcome was nausea and/or vomiting (NV) in the intraoperative, early (0–2 h) or late (2–24 h) postoperative period.

Multivariate statistical analysis was conducted with a regression analysis and a backward elimination of factors without significant correlation.

Results

All prophylactic agents significantly reduced NV incidence intraoperatively. Relative risk reduction for NV by prophylaxis was most effective (59.5%) in Group II (tropisetron and metoclopramide). In Group III (dimenhydrinate and dexamethasone), NV risk was reduced by 29.9% and by 28.7% in Group IV (tropisetron mono-therapy). The incidence of NV in the early (0–2 h) and the late (2–24 h) postoperative period was low all over (7.8%), but the relative risk reduction of NV in the early postoperative period was 54.1% (Group IV), 45.1% (Group III), and 34.8% (Group II), respectively. In the late postoperative period, there was no significant difference between the 4 groups.

Conclusions

We recommend a prophylactic medication with tropisetron 2 mg and metoclopramide 20 mg for patients during caesarean section. These agents are safe, reasonably priced, and highly efficient in preventing nausea and vomiting.

[Postoperative nausea and vomiting and opioid-induced nausea and vomiting: guidelines for prevention and treatment]

Postoperative nausea and vomiting (PONV) causes patient discomfort, lowers patient satisfaction, and increases care requirements. Opioid-induced nausea and vomiting (OINV) may also occur if opioids are used to treat postoperative pain. These guidelines aim to provide recommendations for the prevention and treatment of both problems. A working group was established in accordance with the charter of the Sociedad Española de Anestesiología y Reanimación. The group undertook the critical appraisal of articles relevant to the management of PONV and OINV in adults and children early and late in the perioperative period. Discussions led to recommendations, summarized as follows: 1) Risk for PONV should be assessed in all patients undergoing surgery; 2 easy-to-use scales are useful for risk assessment: the Apfel scale for adults and the Eberhart scale for children. 2) Measures to reduce baseline risk should be used for adults at moderate or high risk and all children. 3) Pharmacologic prophylaxis with 1 drug is useful for patients at low risk (Apfel or Eberhart 1) who are to receive general anesthesia; patients with higher levels of risk should receive prophylaxis with 2 or more drugs and baseline risk should be reduced (multimodal approach). 4) Dexamethasone, droperidol, and ondansetron (or other setrons) have similar levels of efficacy; drug choice should be made based on individual patient factors. 5) The drug prescribed for treating PONV should preferably be different from the one used for prophylaxis; ondansetron is the most effective drug for treating PONV. 6) Risk for PONV should be assessed before discharge after outpatient surgery or on the ward for hospitalized patients; there is no evidence that late preventive strategies are effective. 7) The drug of choice for preventing OINV is droperidol.

Droperidol has comparable clinical efficacy against both nausea and vomiting

BACKGROUND

Droperidol is commonly noted to be more effective at preventing postoperative nausea (PON) than vomiting (POV) and it is assumed to have a short duration of action. This may be relevant for clinical decisions, especially for designing multiple-drug antiemetic regimens.

METHODS

We conducted a post hoc analysis of a large multicentre trial. Within this trial, 1734 patients underwent inhalation anaesthesia and were randomly stratified to receive several antiemetic interventions according to a factorial design, one of which was droperidol 1.25 mg vs placebo. We considered differences to be significant when: (i) point estimates of one outcome are not within the limits of the confidence interval (CI) of the other outcome; and (ii) differences in risk ratio (also known as relative risks, RR) are at least 20%.

RESULTS

Over 24 h, nausea was reduced from 42.9% in the control to 32.0% in the droperidol group, corresponding to a relative risk (RR) of 0.75 (95% CI from 0.66 to 0.84). Vomiting was reduced from 15.6% to 11.8%, and therefore associated with a similar RR of 0.76 (0.59-0.96). In the early postoperative period (0-2 h), droperidol prevented nausea and vomiting similarly, with an RR of 0.57 (0.46-0.69) for nausea and 0.56 (0.37-0.85) for vomiting. In the late postoperative period (2-24 h), the RR was again similar with 0.83 (0.72-0.96) for nausea compared with 0.89 (0.66-1.18) for vomiting but significantly less compared with the early postoperative period.

CONCLUSIONS

We conclude that droperidol prevents PON and POV equally well, yet its duration of action is short-lived.

Klinische Pharmakologie

The rule of three describes three steps which are needed for an optimal control of postoperative nausea and vomiting (PONV). Firstly, patients at high risk of PONV need to be identified. Knowledge about predictive factors may help to identify patients who may best profit from prophylaxis and those where prophylaxis is not worthwhile since the baseline risk is too low. Secondly, for high-risk patients a low emetogenic anaesthesia technique should be chosen, and thirdly, these patients should additionally receive a prophylactic antiemetic cocktail. At present, butyrophenones (e.g. droperidol), 5-HT(3) receptor antagonists ("setrons") and steroids (e.g. dexamethasone) are the most rational choices for the antiemetic cocktail. Although there is strong evidence that there is an additive effect when these antiemetics are combined, economic constraints may influence the number of antiemetics that are eventually chosen. Identification of high-risk patients remains the most difficult part of the rule of three. Risk scores have been proposed and have been widely implemented in clinical practice. The sensitivity and specificity of such scores, however, remain particularly unsatisfactory. Unless more reliable risk scores are developed, aggressive treatment of established PONV symptoms may be more useful and more cost-effective than prophylaxis for many patients.

[Prevention and treatment of postoperative nausea and vomiting in children. An evidence-based approach]

Significant improvement towards an efficacious control of postoperative nausea and vomiting (PONV) has taken place recently. These improvements may be summarised using the "rule of three". That rule describes a pragmatic and rational approach of PONV control. First, identify the patient at risk using predictive factors. Second, modify the anaesthesia technique to keep the baseline risk as low as possible. Third, administer antiemetics rationally, considering their degree of efficacy, their risk, and their potential additive effects. Despite considerable research efforts, identifying the patient at high risk of PONV remains a difficult task. However, today, we understand the degree of efficacy, dose-responsiveness, and adverse effects of most antiemetics. None of those molecules should be regarded as being universally efficacious, there is no gold standard, and, when used alone, their degree of efficacy is limited. Thus, they should be combined for improved efficacy. Among the most promising molecules are butyrophenones (droperidol, haloperidol), 5-HT(3) receptor antagonists (ondansetron, dolasetron, tropisetron, granisetron), and steroids (for instance, dexamethasone). The lack of relevant paediatric PONV data remains a major drawback and is highly unsatisfactory. Hopefully, future research will further improve the control of PONV not only in adults but also in children.

Patient-controlled analgesia in the management of postoperative pain

Patient-controlled analgesia (PCA) is a delivery system with which patients self-administer predetermined doses of analgesic medication to relieve their pain. Since its introduction in the early 1980s, the daily management of postoperative pain has been extensively optimised. The use of PCA in hospitals has been increasing because of its proven advantages over conventional intramuscular injections. These include improved pain relief, greater patient satisfaction, less sedation and fewer postoperative complications. All PCA modes contain the following variables: initial loading dose, demand dose, lockout interval, background infusion rate and 1-hour or 4-hour limits. Morphine is the most studied and most commonly used intravenous drug for PCA. In spite of the fact that it is the 'first choice' for PCA, other opioids have been successfully used for this option. The most observed adverse effects of opioid-based PCA are nausea and vomiting, pruritus, respiratory depression, sedation, confusion and urinary retention. Although intravenous PCA is the most studied route of PCA, alternative routes have extensively been described in the literature. PCA by means of peridural catheters and peripheral nerve catheters are the most studied. Recently, transdermal PCA has been described. The use of peripheral or neuraxial nerve blocks is recommended to avoid the so called opioid tolerance observed with the intravenous administration of opioids. Numerous studies have shown the superiority of epidural PCA to intravenous PCA. The beneficial postoperative effects of epidural analgesia are more apparent for high-risk patients or those undergoing higher risk procedures. PCA with peripheral nerve catheters results in increased postoperative analgesia and satisfaction for surgery on upper and lower extremities. Serious complications occur rarely with these catheters. With the introduction of an Acute Pain Service, management of postoperative pain can be improved. This will also help to minimise adverse effects related to PCA and to avoid lethal mishaps.

Intravenous droperidol: a review of its use in the management of postoperative nausea and vomiting

Droperidol (Dehydrobenzperidol, Dehidrobenzoperidol, Dridol, Droleptan, Inapsine) is a dopamine D(2) receptor antagonist that has been widely used in adults and children for the prevention and treatment of postoperative nausea and vomiting (PONV) over several decades and, more recently, for the prevention of opioid-induced PONV during patient-controlled analgesia (PCA) in adults. In well controlled clinical trials of patients undergoing surgery, the efficacy of single-dose intravenous (IV) droperidol in preventing PONV was similar to that of ondansetron and dexamethasone. Droperidol significantly reduced opioid-induced PONV in adults during PCA and had a morphine-sparing effect. Droperidol is generally well tolerated and the incidence of adverse effects is similar to that observed with placebo and the serotonin 5-HT(3) receptor antagonists (setrons). Guidelines recommend that, in adults, droperidol monotherapy be considered for those at moderate risk of PONV, and droperidol in combination with a setron and/or dexamethasone be considered for patients at moderate or high risk of PONV. In children with moderate or high risk of PONV, droperidol is recommended for first-line use in some countries, and second-line use in others.

Patient-controlled analgesia

One of the most common methods for providing postoperative analgesia is via patient-controlled analgesia (PCA). Although the typical approach is to administer opioids via a programmable infusion pump, other drugs and other modes of administration are available. This article reviews the history and practice of many aspects of PCA and provides extensive guidelines for the practice of PCA-administered opioids. In addition, potential adverse effects and recommendations for their monitoring and treatment are reviewed.

Number needed to treat (or harm)

The effect of a treatment versus controls may be expressed in relative or absolute terms. For rational decision-making, absolute measures are more meaningful. The number needed to treat, the reciprocal of the absolute risk reduction, is a powerful estimate of the effect of a treatment. It is particularly useful because it takes into account the underlying risk (what would happen without the intervention?). The number needed to treat tells us not only whether a treatment works but how well it works. Thus, it informs health care professionals about the effort needed to achieve a particular outcome. A number needed to treat should be accompanied by information about the experimental intervention, the control intervention against which the experimental intervention has been tested, the length of the observation period, the underlying risk of the study population, and an exact definition of the endpoint. A 95% confidence interval around the point estimate should be calculated. An isolated number needed to treat is rarely appropriate to summarize the usefulness of an intervention; multiple numbers needed to treat for benefit and harm are more helpful. Absolute risk reduction and number needed to treat should become standard summary estimates in randomized controlled trials.

Intravenous patient-controlled analgesia: one size does not fit all

Patient-controlled analgesia was introduced as a technique that would allow greater flexibility in opioid delivery for the management of acute pain. However, so far, any benefit compared with conventional methods of pain relief appears to be small. This article reviews some of the factors that could limit the usefulness of intravenous patient-controlled analgesia in the clinical setting and what strategies might allow patient-controlled analgesia to become more effective.

Antiemetic and analgesic-sparing effects of diphenhydramine added to morphine intravenous patient-controlled analgesia

BACKGROUND

This study was designed to examine the analgesic and dose-related antiemetic efficacy of diphenhydramine-morphine mixture for intravenous patient-controlled analgesia (PCA).

METHODS

Healthy women, undergoing abdominal total hysterectomy were recruited to this double-blinded randomized placebo-controlled study. Patients were randomly allocated to one of three groups (n=40 each). In group 1, patients received saline at induction and morphine 1 mg ml(-1) alone for postoperative PCA. Patients in groups 2 and 3 received diphenhydramine 30 mg i.v. at induction and were given a 1.2:1 or a 4.8:1 ratio, respectively, of diphenhydramine-morphine mixture for postoperative PCA.

RESULTS

A total of 112 patients completed the study. The incidence of postoperative nausea (31.6% vs 67.6%, P<0.01) and vomiting (15.8% vs 40.5%, <0.05) was significantly lower in group 3 than in group 1. Furthermore, the incidence of severe nausea was significantly lower in group 3 than in group 1 (2.6% vs 24.3%, P<0.05). The rescue antiemetic requirements were also significantly less in group 3 than in group 1 (5.3% vs 24.3%, P<0.05). However, there was no significant difference between group 2 and group 1 in any of the comparisons. Pain intensity, 24-h morphine consumption and diphenhydramine-related side-effects, such as sedation or dry mouth, did not differ among the three groups.

CONCLUSION

An initial bolus of diphenhydramine 30 mg at anaesthetic induction followed by postoperative PCA with a 4.8:1, but not 1.2:1, diphenhydramine-morphine mixture provides an effective antiemetic efficacy without morphine-sparing effects.

Strategies for postoperative nausea and vomiting

Significant improvement towards a better control of postoperative nausea and vomiting have been achieved in recent years. Today, we understand better who is likely to vomit or to be nauseous after surgery. Significant amounts of the huge literature on anti-emetic interventions have been systematically reviewed, critically appraised and quantitatively synthesized. Thus, we know what anti-emetic interventions work, and how well they work, and we know their adverse effect profile. We also know which interventions have no worthwhile efficacy. A rational approach to postoperative nausea and vomiting includes three steps: identification of patients at risk, keeping the baseline risk low, and prophylactic administration of anti-emetics in those patients who are most likely to need them. For patients who are identified as high-risk patients, all measurements should be simultaneously initiated (multimodal anti-emesis).

Evidence-based management of postoperative nausea and vomiting: a review

PURPOSE

To provide evidence-based guidelines for the prophylaxis and treatment of postoperative nausea and vomiting (PONV).

SOURCE

Literature from randomized controlled trials, systematic reviews, logistic regression analyses and expert opinion in the management of PONV.

PRINCIPAL FINDINGS

The etiology of PONV is multifactorial. Patient, anesthesia, and surgery related risk factors have been identified. Universal PONV prophylaxis is not cost-effective. Identification of patients at high-risk of PONV allows targeting prophylaxis to those who will benefit most from it. No prophylaxis is needed for patients at low risk for PONV. For patients at moderate risk for PONV, prophylaxis using a single antiemetic or a combination of two agents should be considered. Double and triple antiemetic combinations should be considered for patients at high risk for PONV. Furthermore, a multimodal approach should be adopted incorporating steps to keep the baseline risk of PONV low. The optimum cost-effective approach to the management of PONV will differ between an ambulatory centre and an inpatient hospital setting. For the treatment of established PONV in patients who failed prophylaxis, patients should not receive a repeat dose of the prophylactic antiemetic. Rather, a drug acting at a different receptor should be used. Beyond six hours after surgery, patients can be treated with any of the agents used for prophylaxis, except dexamethasone and transdermal scopolamine.

CONCLUSION

PONV are common after anesthesia and surgery. We provided evidence-based guidelines for the management of this problem based on the available literature.

[Postoperative nausea and vomiting]

Numerous pathophysiological mechanisms are known to cause nausea or vomiting but their role for postoperative nausea and vomiting (PONV) is not quite clear. Volatile anesthetics, nitrous oxide and opioids appear to be the most important causes for PONV. Female gender, non-smoking and a history of motion sickness and PONV are the most important patient specific risk factors. With these risk factors an objective risks assessment is achievable as a good rational basis for a risk dependent antiemetic approach: When the risk is low, moderate, or high, the use of none, a single or a combination of prophylactic antiemetic interventions seems to be justified. Performing a total intravenous anesthesia (Ti.v.A) with propofol is a reasonable prophylactic approach, but does not solve the problem satisfactorily alone if the risk is very high, reducing the risk of PONV only by 30%. This is comparable to the reduction rate of antiemetics, such as serotonin antagonist, dexamethasone and droperidol. It must be stressed that metoclopramide is ineffective. Data from IMPACT indicate that prophylaxis is not very effective if the patients risk is low. At a moderate risk the use of Ti.v.A or an antiemetic is reasonable and only a (very) high risk justifies the combination of several prophylactic antiemetic interventions. For the treatment of PONV an antiemetic should be chosen which has not been used prophylactically. The necessary doses are usually a quarter of those needed for prophylaxis.