A single dose of morphine sulfate increases the incidence of vomiting after outpatient inguinal surgery in children

My child is unique; the pharmacokinetics are universal

The pharmacokinetic (PK) parameters that are important for dosing (e.g., clearance and volume) are well known. They are used in universal mathematical formulae that describe the time course of drug concentration. Additional formulae can be used to describe major covariate effects in children, such as size and maturation. PK parameters describing the time-concentration profile of a drug after administration are those for a typical individual in a population. These parameters are associated with variability. Further, any one individual may not be typical of the population studied. While size and maturation are two important considerations in children and assist with dosing estimation, there are also a number of additional PK covariates (e.g., organ function, disease, drug interactions, pharmacogenetics), and identifying these sources of variability allows us to individualize drug dose. Pharmacology is not simply an application of PK, and determinants of drug dose also require an understanding of the variability associated with pharmacodynamic response and a balancing of beneficial effects against unwanted effects. Each child is unique in this respect.

A qualitative systematic review of morphine treatment in children with postoperative pain

BACKGROUND

Postoperative pain management in children is often empirical rather than evidence based. Morphine is the pharmacological treatment most widely used and although considered safe for children, adequate scientific data on morphine's pharmacokinetics, efficacy and safety are lacking. This systematic review aimed to evaluate the available literature examining different pediatric morphine regimens with respect to dosage, analgesic efficacy and incidence of side effects.

METHODS

Thirty-six randomized, double-blind controlled clinical trials with 49 comparisons, including multiple dosage regimens and routes of administration were included. The primary outcome measures for analgesic efficacy (pain intensity, time to first analgesic request and need for rescue analgesics) together with the incidence of morphine-related side effects were evaluated qualitatively by significant difference (P < 0.05) as reported in the original investigations.

RESULTS

Overall, significant improvements in the defined outcome measures on analgesic efficacy were only observed when morphine was compared with inactive control interventions. No relation between morphine dosage and analgesic efficacy was detected. The most common morphine-related side effects were vomiting and sedation, with significantly higher incidences observed after morphine administration in half of all comparisons.

CONCLUSIONS

Although several factors may justify its use as first line therapy in many parts of the world, morphine alone is not the most suitable analgesic for postoperative pain in pediatric patients, as it does not have superior analgesic effect and a higher incidence of side effects compared with active control interventions. More standardized clinical trials with multimodal regimens as well as guidelines for evaluating pediatric medicines are desirable in the future.

Postoperative pain treatment for ambulatory surgery

One of the most significant changes in surgical practice during the last two decades has been the growth of ambulatory surgery. Adequate postoperative analgesia is a prerequisite for successful ambulatory surgery. Recent studies have shown that large numbers of patients suffer from moderate to severe pain during the first 24-48 hr. The success of fast-tracking depends to a considerable extent on effective postoperative pain management routines and the cost saving of outpatient surgery may be negated by unanticipated hospital admission for poorly treated pain. Depending on the intensity of postoperative pain current management includes the use of analgesics such as paracetamol, NSAIDs including coxibs and tramadol as single drugs or in combination as part of balanced (multimodal) analgesia. However, in the ambulatory setting many patients suffer from pain at home in spite of multimodal analgesic regimens. Sending patients home with perineural, incisional, and intra-articular catheters is a new and evolving area of postoperative pain management. Current evidence suggests that these techniques are effective, feasible and safe in the home environment if appropriate patient selection routines and organization for follow-up are in place.

Subtenon lidocaine vs topical proparacaine in adult strabismus surgery

Intraoperative subtenon 2% lidocaine and topical 0.5% proparacaine in patients undergoing strabismus surgery were compared. No additional systemic analgesics and sedatives were used. Mean and total pain scores intraoperatively and postoperatively were not different. Each anesthetic agent provides good intraoperative anesthesia and postoperative analgesia. Topical 0.5% proparacaine may be preferred because of its easy administration and fewer side effects, lack of hospital admission, and immediate and predictable alignment of the eyes.

Patients' willingness to pay for anti-emetic treatment

BACKGROUND

Post-operative nausea and vomiting (PONV) is a common complication of anaesthesia. This study was conducted in 100 German and 100 Turkish patients scheduled for elective surgery under general anaesthesia to assess the amount patients were willing to pay for an anti-emetic that completely prevented PONV.

METHODS

Post-operatively, using Dixon's up and down method, patients completed an interactive computer questionnaire with a random starting point to determine how much of their own money they were willing to pay for a totally effective anti-emetic treatment.

RESULTS

On average, participants were willing to pay 65 euro in Germany and 68 euro in Turkey to avoid PONV. However, patients who actually experienced PONV were willing to pay larger amounts: 96 euro in Germany and 99 euro in Turkey. The amount patients were willing to pay was related to female sex, history of motion sickness, non-smoking status and better education.

CONCLUSIONS

Despite differences in political and cultural origin, health care system and financial background, the amount patients were willing to pay for an effective anti-emetic was similar in both Germany and Turkey to that reported previously for the USA.

The Analgesic Efficacy of Acetaminophen, Ketoprofen, or Their Combination for Pediatric Surgical Patients Having Soft Tissue or Orthopedic Procedures

The combined use of acetaminophen and a nonsteroidal antiinflammatory drug has been shown to provide better postoperative analgesia than either drug alone in several adult studies. However, there are no pediatric studies analyzing similar effects when the currently recommended doses of acetaminophen are used. In a double-blind, placebo-controlled design we randomized 120 children, aged 1-9 yr, undergoing orthopedic or soft tissue surgery, into 3 groups to receive either acetaminophen 60 mg/kg rectally and 40 mg/kg orally, ketoprofen 2 mg/kg IV twice, or the combination of the active drugs. The first drug doses were given at anesthetic induction and the second doses 8 h thereafter. During anesthesia all children received sevoflurane and a continuous infusion of remifentanil. Postoperative pain was evaluated by the behavioral objective pain scale (0-9) for 24 h. The rescue medication was morphine 0.05 mg/kg IV. The primary outcome variable was morphine consumption. For statistical analysis, analysis of variance, chi2 test and Kaplan-Meier survival analysis were used. Morphine requirement was less in the combination than in the acetaminophen group both in the postanesthesia care unit (2.5 +/- 1.7 versus 3.9 +/- 2.1 morphine doses) and during the 24-h postoperative follow-up (4.1 +/- 2.5 versus 5.9 +/- 2.9 morphine doses) (P < 0.05). No differences existed between the ketoprofen and the acetaminophen groups. The objective pain scale scores were lowest in the combination group both in the postanesthesia care unit and in the postoperative ward (P < 0.05). When children were divided based on their surgery, opioid requirement and pain scores were less in the combination than in the parent drug groups only after orthopedic surgery. The combination of acetaminophen 100 mg/kg and ketoprofen 4 mg/kg in a day provided better analgesia and lower pain scores after orthopedic, but not soft tissue, surgery in children.

Propacetamol and diclofenac alone and in combination for analgesia after elective tonsillectomy

BACKGROUND

Diclofenac and paracetamol have different mechanisms and sites of action. Therefore, we tested if their combination is more effective for analgesia after tonsillectomy than either drug alone with respect to rescue analgesic consumption and visual analog scale values.

METHODS

The analgesic effects of intravenously administered propacetamol (injectable pro-drug of paracetamol) and diclofenac or a combination on postoperative pain were compared in 71 adult elective tonsillectomy patients in a randomized, double-blind study. After induction of anesthesia the patients received monotherapy with 2 g propacetamol (n = 25) or 75 mg diclofenac (n = 25), or a combined treatment with 2 g propacetamol and 75 mg diclofenac (n = 21) in physiologic saline as an infusion. Postoperatively the propacetamol dosage was repeated twice and diclofenac once on the ward. Oxycodone (0.03 mg kg(-1)) was used as a rescue analgesic by patient-controlled analgesia.

RESULTS

On average the patients needed oxycodone 15.3, 13.2 and 10.6 times in the propacetamol, diclofenac and combination groups, respectively (NS). A verbal rating scale and a visual analog scale were employed for assessing post-tonsillectomy pain, nausea and patient satisfaction in all groups. No statistically significant differences were found between the groups. Twelve of the 25 (48%) patients having received propacetamol complained of pain at the cannulation site.

CONCLUSION

Combined treatment with propacetamol and diclofenac with the dosages used provided clinically only a minor advantage over monotherapy with propacetamol or diclofenac with respect to postoperative analgesia or the incidence of side-effects in adult tonsillectomy patients.

Amethocaine or ketorolac eyedrops provide inadequate analgesia in pediatric strabismus surgery

PURPOSE

Corrective strabismus surgery is associated with moderate pain after surgery. Postoperative analgesia for these patients may include topical local anesthetic agents and topical non-steroidal anti-inflammatory drugs. In this prospective randomized, double-blind placebo controlled clinical trial we compared the effect of placebo to intraoperative 0.5% topical amethocaine or 0.5% topical ketorolac on pain control after strabismus surgery in children.

METHODS

Following Institutional Ethics Committee approval and parental consent, we prospectively studied 51 healthy children between the ages of two and seven years who were undergoing elective bilateral recession surgery in a randomized, double-blind controlled clinical trial. Children were randomized to receive either placebo (normal saline), 0.5% amethocaine or 0.5% ketorolac eye drops at the start and end of strabismus repair surgery. Pain was assessed with a modified Children's Hospital of Eastern Ontario Pain Score in the recovery room. If the pain score was greater than 6, the patient was administered a single oral dose of acetaminophen (20 mg x kg(-1)).

RESULTS

The groups had similar demographic data. Duration of surgery and anesthesia, time spent in recovery room and length of hospital stay between the three groups were similar. Pain scores and analgesic requirements while in the hospital were also similar between the groups as was the time to first analgesic administration. There were no side effects observed in any of the three treatment arms.

CONCLUSION

We conclude that there is no improvement in postoperative pain control after the intraoperative administration of topical 0.5% ketorolac or 0.5% amethocaine when compared to placebo in children undergoing strabismus surgery.

The effect of remifentanil or fentanyl on postoperative vomiting and pain in children undergoing strabismus surgery

Postoperative vomiting (POV) after strabismus surgery in children results in discomfort and prolonged hospital stays. Opioids increase the incidence of POV. Remifentanil has a context-sensitive half-life of 3 to 4 min, and how this short half-life influences POV in those patients is unknown. We conducted a prospective, double-blinded study in 81 ASA status I or II children from 2 to 12 yr of age undergoing elective strabismus surgery under general anesthesia. Patients were randomized to receive either remifentanil (bolus 1 microg/kg; infusion 0.1-0.2 microg x kg(-1) x min(-1)) or fentanyl (2 microg/kg, and 1 microg/kg every 45 min). POV episodes were recorded for 25 h. Pain scores were obtained by using an objective pain scale for 60 min during recovery. The number of patients who experienced POV did not differ significantly between groups (49% vs 48%). However, in the Remifentanil group, POV episodes were significantly less frequent (0.95 vs 2.2 episodes). In contrast, fentanyl was associated with lower pain scores during the first 30 min of recovery. We conclude that children undergoing strabismus surgery under balanced anesthesia with remifentanil, compared with fentanyl, showed less frequent POV. However, early postoperative analgesia was better with fentanyl.

IMPLICATIONS

Opioids increase the incidence of postoperative vomiting (POV). Remifentanil is characterized by the shortest half-life of all opioids used in anesthetic practice. Therefore, we studied the effect of remifentanil on POV compared with the longer-acting opioid fentanyl in children undergoing strabismus surgery.

Office-based anesthesia for children

The use of office-based surgery and anesthesia will continue to grow. The anesthesia community has embraced the opportunity to become a driving force of office-based surgery and has organized into rapidly growing groups that promote safe practice in the office setting. The Society for Office-Based Anesthesia was developed to continuously improve patient safety and outcomes in office surgery. This group has an active Web site (www.soba.org) that allows for online discussions and widespread participation in working toward the society's stated goal. This Web site may be used as a reference for physicians in the process of considering the move to office-based anesthesia. The advantages of office-based anesthesia are numerous. The financial incentives are tremendous and the convenience to the patient and surgeon is important. For office anesthesia to be successful in children, patient safety, proof of improved outcomes, and family and surgeon satisfaction must be the goals. Anesthesia providers must continue to take active roles in organizing the office environment to ensure that safety is paramount. As the field grows, additional ways to study and improve the overall care children receive in the office should be sought. In the near future, office practice for surgery and anesthesia for children undergoing minor procedures should be a safe and effective alternative to current practices.

Cisapride does not prevent postoperative vomiting in children

The peripherally acting prokinetic drug cisapride can overcome opioid-induced gastrointestinal paresis and may thereby eliminate a stimulus for postoperative vomiting. We conducted a prospective, randomized, double-blinded, controlled trial of 96 children undergoing inguinal surgery to determine whether cisapride would reduce the incidence of postoperative vomiting after general anesthesia supplemented with morphine. Group C1 patients (n = 38) received cisapride 0.3 mg/kg orally 1 h before surgery and placebo 6 h later, Group C2 (n = 28) received cisapride both before and after surgery, and Group P (n = 30) received placebo. Mean age (5.0 +/- 2.7 yr) and weight (21.0 +/- 8.6 kg), median pain scores and parent satisfaction scores, and incidence of rescue analgesic administration were similar across groups. Contrary to our hypothesis, incidences of postoperative vomiting in the hospital (32% vs 20%, P = 0.33) and at home (53% vs 46%, P = 0.33) did not vary by treatment group (with [C1 and C2] and without [P] cisapride, respectively). There was a trend toward more severe postoperative vomiting (three or more episodes) in children who received cisapride versus those who did not, both in hospital (6% vs 0%, P = 0.3) and at home (22% vs 8%) (P = 0.13). We conclude that cisapride does not prevent postoperative vomiting in this patient population and speculate that factors other than reduced gastrointestinal motility associated with general anesthesia and opioids are more important determinants of postoperative vomiting.

IMPLICATIONS

Cisapride does not prevent postoperative vomiting in children and may increase its severity.

Investigations using logistic regression models on the effect of the LMA on morphine induced vomiting after tonsillectomy

The effect of intraoperative airway management on postoperative vomiting after tonsillectomy is unknown. Logistic regression was used in a retrospective study to investigate the effect of the laryngeal mask airway (LMA) on a morphine dose-vomiting response curve. Charts were reviewed in 351 children in whom the airway was managed with either a LMA (n=177) or a tracheal tube (n=174). A mean perioperative morphine dose of 0.10 mg.kg(-1) (SD 0.09) was used in 248 children and a further 103 children were given no opioid. One hundred and eighteen of these 248 children vomited (47.6%) compared to 14 of 103 children given no morphine (13.6%). The probability of vomiting was related to morphine dose using logistic regression with both a linear and an E(max) model. Both the calibration (Hosmer-Lemishow goodness of fit chi-squared test lambda(2), P=0.81) and discrimination (area under the receiver operating characteristic plot, AUC ROC=0.67) of the E(max) model were better than the linear model (lambda(2), P=0.49; AUC ROC=0.64). Pharmacodynamic parameter estimates for the Emax model were P(0) (the baseline probability of vomiting) 0.139, P(max) (the maximal probability of vomiting due to morphine) 0.96, ED(50) (morphine dose that induces an effect equivalent to 50% of the logit P(max)) 0.09 mg.kg-1. The probability of vomiting was 50% after morphine 0.125 mg.kg-1. The use of the LMA had no effect on this dose-response curve. A covariate analysis investigating propofol for induction or isoflurane for the intraoperative maintenance of anaesthesia, however, showed that both drugs shifted the curve to the right. The probability of vomiting was 50% after morphine 0.17 mg.kg(-1) and 0.21 mg.kg(-1) for the isoflurane and propofol use curves, respectively. The concomitant use of propofol and isoflurane, but not the use of the LMA, decreases the probability of vomiting due to morphine.

Ketorolac reduces postoperative narcotic requirements

BACKGROUND/PURPOSE

Adverse effects from narcotics complicate pain management in children. Ketorolac, a potent nonsteroidal antiinflammatory agent can be used as an adjuvant analgesic, yet concerns of bleeding and nephrotoxicity have limited routine use. The authors hypothesized that postoperative use of ketorolac in healthy pediatric surgical patients would limit narcotic requirements without increasing morbidity.

METHODS

A case-control clinical trial was conducted of 29 pediatric surgical cases prospectively administered ketorolac (0.5 mg/kg intravenously every 6 hours) supplemented with morphine. Controls receiving morphine only were matched for age (+/- 6 months) and surgical procedure. Incidence of respiratory depression, urinary retention, emesis, nephrotoxicity, and bleeding were recorded.

RESULTS

Patients receiving ketorolac plus morphine had significantly less morphine requirements in the first 48 postoperative hours (Ketorolac plus Morphine: 0.36+/-0.16 mg/kg/d, Morphine only: 1.08+/-0.16 mg/kg/d [P<.05, analysis by paired t test]). This decrease was noted despite mode of analgesia (patient controlled or nurse administered). Adverse effects of morphine including respiratory depression, emesis, and urinary retention were not affected by ketorolac. Patients administered ketorolac had no significant increase in bleeding or nephrotoxicity.

CONCLUSION

Ketorolac exhibits significant opiate-sparing effects in the immediate postoperative period without introducing additional morbidity to pediatric surgical procedures.

The dose-effect relationship for morphine and vomiting after day-stay tonsillectomy in children

A dose-response curve for intravenous morphine and vomiting was investigated in children having day-stay tonsillectomy. A retrospective chart review was performed for the 164 children fulfilling the inclusion criteria. Morphine (mean 0.09 mg/kg SD 0.05) was used in 108 children in the perioperative period and a further 56 children were given no opioid. Fifty-five of these 164 children vomited and 20 children required an overnight stay in hospital because of vomiting. The probability of vomiting or overnight stay in hospital was related to morphine dose (by logistic regression). The overall probability of vomiting after morphine 0.1 mg/kg was 50% and the probability of admission for vomiting with this dose was 10%. Pharmacodynamic parameter estimates for postoperative vomiting were P0 (the baseline probability of vomiting, with no opioid) 0.115, Pmax (the maximal probability of vomiting due to morphine) 0.997, ED50 (morphine dose that induces an effect equivalent to 50% of the logit Pmax) 0.18 mg/kg. Parameter estimates for overnight stay because of vomiting after morphine administration were P0 0.038, Pmax 0.999, ED50 0.369 mg/kg. Satisfactory postoperative analgesia in children has been reported with morphine 0.05 to 0.15 mg/kg. Doses above 0.1 mg/kg are associated with a greater than 50% incidence of vomiting. Our data suggests that lower doses of morphine are associated with a decreased incidence of emesis after tonsillectomy in children.

Preoperative anxiety and postoperative nausea and vomiting in children: is there an association?

We performed a cross-sectional study to explore a potential association between preoperative anxiety and postoperative nausea and vomiting (PONV). The study enrolled 51 unpremedicated children 5-16 yr old undergoing outpatient surgery and standardized general anesthesia. Anxiety of children was assessed in the preoperative holding area and during the induction of anesthesia. The incidence of nausea and vomiting was documented in the postanesthesia care unit (PACU) and 24 h postoperatively (POD#1). In addition to univariate analysis, we used multivariate logistic regression models, wherein the dependent variable was the presence or absence of PONV and the independent variables included potential confounders such as age, sex, and perioperative opioid consumption. Univariate analysis showed that children who experienced nausea (32 +/- 5 vs 31 +/- 4, P = ns) or vomiting (32 +/- 4 vs 32 +/- 5, P = ns) in the PACU did not differ significantly in their anxiety before surgery. A multivariate model, in which the dependent variable was the presence or absence of vomiting at POD#1 and the independent variables included preoperative anxiety, age, sex, and opioid consumption, indicated that preoperative anxiety does not predict the occurrence of nausea and vomiting (P = ns). We conclude that children's anxiety in the preoperative holding area has no predictive value for the occurrence of PONV in the PACU or POD#1.

IMPLICATIONS

This study was performed to explore a possible association between children's anxiety before surgery and postoperative nausea and vomiting. We found that controlling for confounding variables, anxiety in the preoperative holding area has no predictive value for the occurrence of postoperative nausea and vomiting.

Efficacy and complications of morphine infusions in postoperative paediatric patients

The aim of the study was to evaluate the efficacy and the incidence of clinically significant adverse drug reactions (ADRs) in paediatric patients receiving continuous intravenous morphine infusions for acute postoperative pain. Definitions were established for ADRs and data were collected in an immediately retrospective fashion for a maximum of 72 h in 110 patients >/=5 three months of age (0.3-16.7 years) receiving morphine infusions and admitted to a general ward over a three month convenience sampling period. Inadequate analgesia occurred in 65.5% of patients during the first 24 h of therapy and occurred most frequently in patients with infusion rates of 20 microg.kg-1.h-1 or less. Nausea/vomiting was the most commonly experienced ADR (42.5%). The incidence of respiratory depression was 0% (95% CI=0-3.3%). Other ADRs included: urinary retention (13.5%), pruritus (12.7%), dysphoria (7.3%), hypoxaemia (4.5%), discontinuation of morphine for treatment of an ADR (3.6%), and difficulty in arousal (0.9%). The most common ADRs associated with morphine infusions were inadequate analgesia (in the first 24 h) and nausea/vomiting. There were no cases of respiratory depression. Methods of avoiding initial inadequate analgesia and treating nausea and vomiting associated with morphine infusions are needed.

Newer drugs in pediatric anesthesia

Recent developments in pharmacology have offered new and broader options to the anesthesiologist caring for pediatric patients. Many new drugs do not have specific indications for use in the pediatric population, but clinical studies have examined the utility and cost-effectiveness of some of these agents. Information is presented on drugs used for premedication, induction, and maintenance of anesthesia. The clinical pharmacology of several new nondepolarizing muscle relaxants, and the recent controversy with regard to the use of succinylcholine also are presented. New drugs used in topical and regional anesthesia as well as options for anti-emetic therapy are discussed.

Opioid tolerance in neonates: mechanisms, diagnosis, assessment, and management

Opioid tolerance and withdrawal have been challenges for decades. The neurochemical mechanisms of tolerance and dependence are clinically important only because they can affect weaning schedules and the adjustment of doses for neonates. Analgesic effects are characterized by an increased depolarization threshold for the neuron, shorter duration of the action potential generated, and reduced release of neurotransmitters. Tolerance and withdrawal are associated with the reversal of these cellular effects. Adverse clinical effects associated with the use of opioids in neonates include respiratory depression, chest wall rigidity, urinary retention, and decreased gastrointestinal motility. The physiological systems most prominently affected by opioid withdrawal include the central nervous system, gastrointestinal system, and the autonomic nervous system. Opioid withdrawal symptoms in neonates can be assessed by using easily available scoring systems, although these need to be validated for different populations. Management of opioid withdrawal includes the use of other opioids, benzodiazepines and alpha-2 adrenergic receptor antagonist, clonidine. Careful titration of opioids with attention given to appropriate weaning schedules can reduce the incidence of withdrawal in neonates.

Pharmacologic pain management in children: a review of intervention research

In the past decade, an explosion of interest in pediatric pain has resulted in the proliferation of research studies. This review examines 41 studies that focus on pharmacologic interventions in children during the last decade. Criteria for inclusion in this paper were studies that (1) tested a pharmacological intervention prospectively, (2) were conducted with children only, (3) had a sample size over 30, (4) randomly assigned participants to two or more groups, and (5) provided sufficient methodological and statistical detail for critique. Studies focused on postoperative and procedural pain, were conducted most frequently with pre-school-aged children or older, and demonstrated the efficacy of pharmacologic interventions.

A randomized, double-blind, placebo controlled comparison of droperidol, ondansetron, and metoclopramide for the prevention of vomiting following outpatient strabismus surgery in children

STUDY OBJECTIVE

To compare the efficacy of ondansetron, droperidol, or metoclopramide with placebo in preventing postoperative vomiting following strabismus surgery.

STUDY DESIGN

Randomized, double-blind, placebo-controlled clinical trial.

SETTING

University outpatient surgery center.

PATIENTS

160 ASA physical status I and II children ages 1 to 12 years who were scheduled for strabismus surgery.

INTERVENTIONS

Administration of either ondansetron 100 mcg/kg, metoclopramide 250 mcg/kg, droperidol 75 mcg/kg, or placebo intravenously after induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Both ondansetron and droperidol were superior to metoclopramide and placebo in preventing predischarge vomiting, with incidences of 5%, 5%, 32%, and 25%, respectively. However, there was no difference in the incidence of postdischarge vomiting among the groups (ondansetron 25%, droperidol 25%, metoclopramide 20%, and placebo 25%).

CONCLUSIONS

While both ondansetron and droperidol are more effective than metoclopramide when compared with placebo in decreasing the incidence of predischarge vomiting, none of these drugs was more effective than placebo in decreasing the incidence of postdischarge vomiting. Recovery from anesthesia was not significantly different among the groups as assessed by time to awakening, initial Steward score, and time to discharge.

Single-dose ondansetron prevents postoperative vomiting in pediatric outpatients

This randomized, double-blind, parallel-group, multicenter study evaluated the safety and efficacy of ondansetron (0.1 mg/kg to 4 mg intravenously) compared with placebo in the prevention of postoperative vomiting in 429 ASA status I-III children 1-12 yr old undergoing outpatient surgery under nitrous oxide- and halothane-based general anesthesia. The results show that during both the 2-h and the 24-h evaluation periods after discontinuation of nitrous oxide, a significantly greater percentage of ondansetron-treated patients (2 h 89%, 24 h 68%) compared with placebo-treated patients (2 h 71%, 24 h 40%) experienced complete response (i.e., no emetic episodes, not rescued, and not withdrawn; P < 0.001 at both time points). Ondansetron-treated patients reached criteria for home readiness one-half hour sooner than placebo-treated patients (P < 0.05). The age of the child, use of intraoperative opioids, type of surgery, and requirement to tolerate fluids before discharge may also have affected the incidence of postoperative emesis during the 0- to 24-h observation period. Use of postoperative opioids did not have any effect on complete response rates in this patient population. We conclude that the prophylactic use of ondansetron reduces postoperative emesis in pediatric patients, regardless of the operant influential factors.

IMPLICATIONS

Postoperative nausea and vomiting often occur after surgery and general anesthesia in children and are the major reason for unexpected hospital admission after ambulatory surgery. Our study demonstrates that the prophylactic use of a small dose of ondansetron reduces postoperative vomiting in pediatric patients.

Analgesic efficacy of paracetamol in children using tonsillectomy as a pain model

The analgesic efficacy of paracetamol was assessed in a prospective, randomized, double-blinded study of 100 children undergoing tonsillectomy with or without adenoidectomy. Fifty children were given paracetamol elixir 40 mg/kg 40 minutes preoperatively (Group A); the remaining 50 children were given an oral placebo 40 minutes preoperatively and paracetamol suppositories 40 mg/kg after induction of anaesthesia (Group B). Paracetamol was the only analgesic given and was given either orally or rectally in order to produce high variations in plasma paracetamol concentrations postoperatively. At 30 minutes after the end of surgery a pain score (0-10) was obtained and a venous blood sample was taken for serum paracetamol concentration analysis. Children given paracetamol elixir had a higher mean paracetamol concentration (0.15 [SD 0.06] mmol/l vs 0.05 [SD 0.03] mmol/l, P < 0.001) and a lower median pain score (5 vs 7, P < 0.02) than those who were given suppositories. The use of rescue morphine was higher (10 vs 23, P < 0.001) in the latter group. The incidence of nausea and vomiting was the same in both groups (20%) during the 24 hour postoperative period. Plasma paracetamol concentrations of 0.066-0.132 mmol/l are known to reduce temperature; plasma paracetamol concentrations which provide analgesia are unknown. Children with plasma paracetamol concentrations above 0.07 mmol/l had superior analgesia to those with concentrations below this level (P < 0.05).

Postoperative opioid analgesia: time for a reconsideration?

Postoperative pain relief has improved in recent years with the development of new analgesics, additional routes of administration and the appearance of the hypothesis of preemptive as well as balanced analgesia (Kehlet H; Postoperative pain relief-what is the issue? Br J Anaesth 1994;72:375-8). Many initial improvements simply involved the administration of opioid analgesics in new ways, such as continuous or on demand intravenous (i.v.) or epidural infusion. These methods allow lower total opioid dosages, provide a more stable concentration of opioid at the receptor and correspondingly better analgesic effects, and also fewer unwanted side effects. Although opioids have played a prominent role in postoperative analgesia for centuries and are still often administered as a matter of routine, their frequent minor side effects and the increasing availability of suitable alternatives may limit their future use in some situations. Thus, the recent emphasis on ambulatory surgery and accelerated surgical stay programs, both with a focus on early recovery of organ function and provision of functional analgesia [i.e., pain relief that allows normal function (Kehlet H: Postoperative pain relief-what is the issue? Br J Anaesth 1994;72:375-8)] provide an opportunity for a reappraisal of opioid use in these settings. For this debate, controlled clinical studies on the opioid-sparing effect of different analgesic techniques are mentioned, and preferably studies with multiple dosing of analgesics and/or a reasonably large patient sample size. These data do not allow a proper meta-analysis to be performed because of the large variability in surgical procedures, dosing regimens, assessment criteria, among others.

Effects of ondansetron on emesis in the first 24 hours after craniotomy in children

Children undergoing neurosurgical resection are at high risk for postoperative nausea and vomiting. Ondansetron, a selective serotonergic (5-HT3) antagonist, is effective in reducing postoperative vomiting in several high-risk populations. In a prospective, randomized study, we compared the prophylactic use of intravenous ondansetron, 0.15 mg/kg, versus placebo for the prevention of emesis in 60 children, aged 2-18 yr, undergoing craniotomies for resective procedures. Patients with preoperative emesis were excluded from the study. All patients were tracheally extubated at the conclusion of surgery, and each episode of emesis during the first 24 postoperative hours was recorded. For the entire 24-h interval, the incidence of emesis in children who received ondansetron (57%) was not significantly different from that in those who received placebo (66%); however, in the first 8 h, the incidence was 25% (ondansetron) vs 44% (placebo) (P = not significant). In those receiving placebo, there was no difference in emesis between patients undergoing operations above versus below the tentorium. Although our sample size was too small to completely exclude any beneficial effect, ondansetron appears ineffective in preventing postoperative emesis in this patient population.

Preoperative ketorolac increases bleeding after tonsillectomy in children

PURPOSE

To compare the incidence of vomiting following codeine or ketorolac for tonsillectomy in children.

METHODS

We had planned to enrol 240 patients, aged 2-12 yr undergoing elective tonsillectomy into a randomized, single-blind study in University Children's Hospital. The study was terminated, after 64 patients because interim analysis of the data by a blinded non-study scientist concluded that the patients were at undue risk of excessive perioperative bleeding. After induction of anaesthesia by inhalation with N2O/halothane or with propofol 2.5-3.5 mg.kg-1 i.v., the children were administered 150 micrograms.kg-1 ondansetron and 50 micrograms.kg-1 midazolam. Maintenance of anaesthesia was with N2O and halothane in O2. Subjects were administered either 1.5 mg.kg-1 codeine im or 1 mg.kg-1 ketorolac i.v. before the commencement of surgery. Intraoperative blood loss was measured with a Baxter Medi-Vac Universal Critical Measurement Unit. Postoperative management of vomiting and pain was standardized. Vomiting was recorded for 24 hr after anaesthesia. Data were compared with ANOVA, Chi-Square analysis and Fisher Exact Test.

RESULTS

Thirty-five subjects received ketorolac. Demographic data were similar. The incidence of vomiting during the postoperative period was 31% in the codeine-group and 40% in the ketorolac-group. Intraoperative blood losses was 1.3 +/- 0.8 ml.kg-1 after codeine and 2.2 +/- 1.9 ml.kg-1 after ketorolac (mean +/- SD) P < 0.05. Five ketorolac-treated patients had bleeding which led to unscheduled admission to hospital, P < 0.05, Exact Test.

CONCLUSION

Preoperative ketorolac increases perioperative bleeding among children undergoing tonsillectomy without beneficial effects.

Recovery and complications after tonsillectomy in children: a comparison of ketorolac and morphine

Ninety-six children received morphine 0.1 mg/kg (n = 47) or ketorolac 1 mg/kg (n = 49) intravenously (IV) in a prospective, randomized, double-blind fashion, after tonsillectomy. Recovery variables and complications were recorded while subjects were in the hospital and parent(s) were contacted 24 h and 14 days after surgery. There were no differences in demographics, surgical management, awakening time, oxygen requirements, or time to readiness for postanesthesia care unit (PACU) discharge or discharge home between the two groups. Ketorolac subjects had fewer emetic episodes than morphine subjects (median 1 vs 3; P = 0.006) and were less likely to have more than two episodes of emesis after PACU discharge (9/49 vs 22/47; P = 0.007). Ketorolac subjects had more major bleeding (bleeding requiring intervention; 5/49 vs 0/47, one-tailed P = 0.03) and more bleeding episodes (0.22 episodes/subject vs 0.04 episodes/subject, P < 0.05) in the first 24 h after surgery, but no greater overall incidence of bleeding than the morphine subjects. In children having tonsillectomy, ketorolac, compared to morphine, reduced the number of emetic episodes after PACU discharge, but did not hasten awakening, readiness for PACU discharge or discharge home, and increased the likelihood of major bleeding in the first 24 h after surgery.

The effects of ketorolac and fentanyl on postoperative vomiting and analgesic requirements in children undergoing strabismus surgery

Fifty-four ASA I and II children 1 to 10 yr of age undergoing strabismus surgery were randomized to receive in a double-blind fashion intravenous ketorolac (0.9 mg/kg), fentanyl (1 microgram/kg), or saline placebo (2 mL) during a standardized general anesthetic. Patients received no analgesic or antiemetics intraoperatively except for the study drug. Patients receiving ketorolac or placebo compared to fentanyl had a significantly lower incidence of postoperative vomiting in the day surgery unit (DSU) (P = 0.03) and overall (DSU plus home) (P = 0.005). The severity (number of episodes) of post-operative vomiting was significantly lower in the DSU, at home (first 24 h after hospital discharge), and overall for patients receiving ketorolac or placebo compared to fentanyl (P < 0.01). Postoperative pain scores and frequency of acetaminophen administration did not differ among the study groups, suggesting that the intraoperative use of ketorolac or fentanyl during pediatric strabismus surgery is unnecessary. No patients required fentanyl postoperatively, indicating that rectal acetaminophen administered in the postanesthesia recovery room provides sufficient analgesia for pediatric strabismus surgery. In conclusion, neither ketorolac nor fentanyl was associated with less postoperative vomiting or analgesic requirements compared to saline placebo administered during pediatric strabismus surgery. Fentanyl should be avoided, as it was associated with a significantly greater incidence of postoperative vomiting compared to ketorolac or placebo.

Regional anaesthesia for hernia repair in children: local vs caudal anaesthesia

The purpose of this study was to compare the effect of local anaesthesia (LA) with that of caudal anaesthesia (CA) on postoperative care of children undergoing inguinal hernia repair. This was a randomized, single-blind investigation of 202 children aged 1-13 yr. Anaesthesia was induced with N2O/O2 and halothane or propofol and maintained with N2O/O2/halothane. Local anaesthesia included ilioinguinal and iliohypogastric nerve block plus subcutaneous injection by the surgeon of up to 0.3 ml.kg-1 bupivacaine 0.25% with 5 micrograms.kg-1 adrenaline. The dose for caudal anaesthesia was 1 ml.kg-1 up to 20 ml bupivacaine 0.2% with 5 micrograms.kg-1 adrenaline. Postoperative pain was assessed with mCHEOPS in the anaesthesia recovery room, with postoperative usage of opioid and acetaminophen in the hospital, and with parental assessment of pain with a VAS. Vomiting, time to first ambulation and first urination were recorded. The postoperative pain scores and opioid usage were similar; however, the LA-group required more acetaminophen in the Day Care Surgical Unit. The incidence of vomiting and the times to first ambulation and first urination were similar. The LA-patients had a shorter recovery room stay (40 +/- 9 vs 45 +/- 15 min, P < 0.02). The postoperative stay was prolonged in the CA group (176 +/- 32 vs 165 +/- 26 min, P = 0.02). We conclude that LA and CA have similar effects on postoperative care with only slight differences.

Prevention of emesis after strabismus repair in children: a prospective, double-blinded, randomized comparison of droperidol versus ondansetron

STUDY OBJECTIVE

To compare the effectiveness of ondansetron with droperidol in preventing postoperative emesis in children after strabismus repair.

DESIGN

Randomized, double-blind study.

PATIENTS AND SETTING

57 ASA physical status I and II children aged 3 to 14 years, undergoing outpatient strabismus repair in two separate study centers.

INTERVENTIONS

Patients were randomized to receive either 0.15 mg/kg intravenous (i.v.) ondansetron or 0.075 mg/kg i.v. droperidol shortly after induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Number of episodes of emesis and times to discharge from the recovery room and ambulatory center were assessed. Twenty-nine (94%) of 31 children who received ondansetron and 21 (81%) of 26 children who received droperidol were emesis-free (p = NS). There were no significant differences in the number of episodes of emesis on the day after surgery or times to discharge.

CONCLUSIONS

Ondansetron is at least as effective as droperidol in reducing the frequency of emesis in children after strabismus repair, and it did not shorten times to discharge home. The low number of patients in our study may have masked a difference in effect between the two groups. The clinician should decide whether the increased cost of ondansetron justifies its use over other antiemetics.