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

Effect of Remifentanil on Postoperative Vomiting After Strabismus Surgery in Preschool Children: A Prospective Randomized Controlled Trial

Background

Strabismus surgery and the use of opioid are risk factors of postoperative vomiting. We evaluated whether there is a dose-dependent effect of remifentanil on the incidence of postoperative vomiting.

Methods

Sixty pediatric patients who were scheduled for strabismus surgery were enrolled. Patients were randomly divided into three groups; Group H (high-dose remifentanil group), Group L (low-dose remifentanil group), and Group C (control group). After endotracheal intubation, patients in the Group H and L received an intravenous bolus dose of remifentanil of 1.0 μg/kg and 0.5 μg/kg over 2 min, respectively. Group H and L patients received a continuous infusion of remifentanil (0.1 μg/kg/min) during the surgery. The patients in Group C did not have any dose of remifentanil. Intravenous fentanyl (1 µg/kg) was administered to the patients for postoperative pain control.

Results

The primary outcome was a difference of the incidence of postoperative vomiting within 24 hours after surgery. There was no significant difference in incidence of postoperative vomiting between three groups. The degree of emergence agitation and postoperative pain did not show any significant difference between three groups.

Conclusions

The intraoperative administration of remifentanil did not show dose-dependent effect on postoperative vomiting in pediatric strabismus surgery.

Comparison of topical oxybuprocaine and intravenous fentanyl in pediatric strabismus surgery

PURPOSE

To compare the outcomes such as postoperative nausea/vomiting, analgesic requirements, and hospital stay following the use of topical oxybuprocaine hydrochloride 0.4% or intravenous (IV) fentanyl in children undergoing strabismus surgery.

METHODS

This was a prospective cohort study. Children operated under general anesthesia for strabismus were given topical oxybuprocaine hydrochloride 0.4% (Group T) and IV fentanyl (Group F) before surgery. The episodes of nausea/vomiting, pain score, requirement of additional analgesia during postoperative period, and duration of hospital stay were compared in two groups.

RESULTS

There were 47 children in Group T and 59 children in Group F. The median pain score in two groups were 2.38 (25% quartile; 2.0) and 3.00 (25% quartile; 3.00), respectively. The difference was significant (K W P < 0.03). The episodes of nausea/vomiting in two groups were in 2 and 6 children in Group T and Group F, respectively. The median hospital stay of children of Group T and Group F were 242 and 285 min, respectively. The difference was not statistically significant (P = 0.22).

CONCLUSIONS

Using intraoperative topical oxybuprocaine drops, one can achieve better analgesic outcomes and reduce risk of nausea and vomiting compared to intravenous opioid analgesics and therefore, the hospital stay could also be marginally reduced.

Ketoprofen for add-on pain treatment to paracetamol after strabismus surgery in children

OBJECTIVE

To evaluate whether combining ketoprofen, a nonsteroidal anti-inflammatory analgesic, with paracetamol would provide better postoperative analgesia than paracetamol alone in children undergoing strabismus surgery.

STUDY DESIGN

A prospective, double-blind, randomised clinical trial.

PATIENTS AND METHODS

56 generally healthy children, aged 3-15 years, undergoing strabismus surgery with standardised endotracheal anaesthesia were randomly assigned to receive either ketoprofen 1 mg/kg intravenously or normal saline at induction of anaesthesia and a second dose 3h later. All children received paracetamol 24 mg/kg solution orally 60 min before surgery and fentanyl 2 mug/kg intravenously during surgery. For rescue analgesia during the first 6h children in pain (pain score >3 on an 11-point scale: 0 = no pain, 10 = worst possible pain) received fentanyl 1 mug/kg intravenously. Any episodes of vomiting and all other adverse events were recorded for the first 24h.

RESULTS

21 of 27 children in the ketoprofen-paracetamol group (78%) and 23 of 29 in the paracetamol group (79%) received fentanyl for rescue analgesia. The mean (SD) number of fentanyl doses during the first 6h was 1.2 (0.9) in the ketoprofen-paracetamol group and 1.7 (1.1) doses in the paracetamol group (mean difference 0.5 doses; 95% CI for difference: -0.1, 1.3; p = 0.11). Eight (30%) vomited in the ketoprofen-paracetamol group and 14 in the paracetamol group (48%) [difference 19%; 95% CI -6, 44; p = 0.15). No serious adverse events occurred.

CONCLUSION

Neither paracetamol nor ketoprofen-paracetamol provided sufficient analgesia for children after strabismus surgery because most needed rescue analgesia.

Sub-Tenon's ropivacaine block for pain relief after primary strabismus surgery

PURPOSE

Pain is the main cause of patient distress/dissatisfaction after strabismus surgery. The aim of the study was to evaluate the effect of sub-Tenon's block with ropivacaine at the end of strabismus surgery on post-operative pain.

METHODS

A prospective trial was conducted in 79 patients (age 1.0-65 years) scheduled for outpatient primary strabismus surgery with fixed sutures under general anesthesia (GA) at a major tertiary hospital. Half the patients were randomly allocated to receive sub-Tenon's block with ropivacaine 0.2% at conclusion of the operation. Primary outcome measures were visual analog scale (VAS) scores at arrival to the post-anesthesia care unit (PACU), at discharge 3 hr later, 12-16 hr post-operatively, and 24 hr post-operatively. Supplemental analgesia requirements and patient satisfaction were recorded as well. Data were presented as median (range). Mann-Whitney test, Pearson chi(2)-test or Fisher's exact test was used for statistical analysis; p <or= 0.05 was considered significant.

RESULTS

There were no between-group differences in median VAS scores at arrival to the PACU and at discharge, with a borderline difference at 24 hr post-operatively (p = 0.06). At 12-16 hr post-operatively, the median score was 0.0 (range 0-5) in the study group and 4.0 (range 0-6) in the controls (p < 0.001). The lower VAS score in the study group was associated with a lower rate of supplemental analgesia use (21.9% versus 57.9%, p = 0.001), fewer doses of supplemental analgesia (10 doses versus 35, p = 0.03), and higher patient satisfaction (p < 0.001).

CONCLUSIONS

Sub-Tenon's block with ropivacaine 0.2% at the completion of outpatient primary strabismus surgery with fixed sutures under GA reduces pain 12-16 hr post-operatively and analgesia requirements 4-23 hr post-operatively.

Review of the efficacy and safety of remifentanil for the prevention and treatment of pain during and after procedures and surgery

Remifentanil is an ultrashort-acting synthetic opioid. It is metabolized by nonspecific tissue and plasma esterases. Remifentanil's metabolism is responsible for its unique pharmacokinetic profile and flat, context-sensitive half-time. Since its introduction into clinical practice, remifentanil has been used for a variety of anesthetic and analgesic applications; however, concerns regarding a potential for rapid induction of tolerance and/or induced hyperalgesia, coupled with an ultrarapid offset of effect, make the drug less than optimal for use in the pharmacologic management of pain.

Incidence of postoperative nausea and vomiting after paediatric strabismus surgery with sevoflurane or remifentanil-sevoflurane

BACKGROUND

In this prospective, randomized, double-blind study, we evaluated and compared the incidence of postoperative nausea and vomiting (PONV) after paediatric strabismus surgery with two different anaesthetic methods, sevoflurane or remifentanil-sevoflurane.

METHODS

In total, 78 paediatric patients (aged 6-11 yr) undergoing strabismus surgery were enrolled and randomly assigned to two groups, sevoflurane (Group S) and remifentanil-sevoflurane (Group R). Anaesthesia was maintained with 2-3% sevoflurane in Group S (n=39) or with a continuous infusion of remifentanil combined with 1% sevoflurane in Group R (n=39), both using 50% N(2)O/O(2). Arterial pressure and heart rate before induction, after tracheal intubation, after skin incision, and at the end of surgery were recorded. The incidence of PONV in the post-anaesthesia care unit, the day surgery care unit, and at home 24 h after surgery was recorded.

RESULTS

Arterial pressure and heart rate were stable throughout the surgery, but were significantly lower in Group R than in Group S after tracheal intubation and skin incision. The incidence of PONV and postoperative vomiting was 17.9%/17.9% and 12.8%/10.2% (Group S/Group R) at the respective time points; values were comparable between the groups.

CONCLUSIONS

The incidence of PONV after paediatric strabismus surgery under sevoflurane anaesthesia was relatively low, and combining remifentanil with sevoflurane did not further increase the incidence.

The potential for mu-opioid receptor agonists to be anti-emetic in humans: a review of clinical data

In animal models of vomiting, mu-opioid (MOP, OP(3)) receptors mediate both emesis and anti-emesis. mu-receptors within the blood-brain barrier, mediating anti-emesis, are more rapidly accessible to lipid-soluble mu-opioid receptor agonists such as fentanyl than to morphine, and fentanyl has broad-spectrum anti-emetic effects in a number of species. Whether a similar situation exists in humans is not known. A search was performed for clinical studies comparing the emetic side effects of opioids administered peri-operatively in an attempt to identify differences between morphine and more lipid-soluble mu-receptor-selective agonists such as fentanyl. Overall, the evidence appears to suggest that fentanyl and other phenylpiperidines are associated with less nausea and vomiting than morphine, but not all studies support this, and fentanyl-like drugs are associated with nausea and vomiting per se. Good evidence, however, exists to show that fentanyl and alfentanil do not cause more nausea and vomiting than the ultra fast-acting remifentanil. Because remifentanil is cleared rapidly post-operatively, such trials suggest that the emetic side effects of fentanyl and alfentanil are minimal. The clinical evidence, although limited, is at least consistent with the possibility that central mu-opioid receptors may mediate anti-emesis in humans. It is possible that the role of mu-opioid agonists in anti-emesis may become clearer in the future as a result of the use of peripheral mu-opioid receptor antagonists.

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.

Less postoperative nausea and vomiting after propofol + remifentanil versus propofol + fentanyl anaesthesia during plastic surgery

BACKGROUND

The effect of different opioids on postoperative nausea and vomiting (PONV) has not been conclusively determined yet, thus the aim of this study was to compare the incidence of PONV in propofol-anaesthetized patients receiving either fentanyl or remifentanil as opioid supplement.

METHODS

Sixty ASA physical status I and II patients scheduled for plastic surgery gave their written informed consent for this prospective, randomized, double-blind study. Anaesthesia was induced with propofol, rocuronium and fentanyl (n = 30; 2 microg kg(-1)) or remifentanil (n = 30; 1 microg kg(-1)). After tracheal intubation, anaesthesia was maintained with propofol, oxygen in air and an infusion of the opioid studied, which was modified according to clinical criteria. Baseline postoperative analgesia was achieved with intravenous propacetamol + metamizol. Intravenous morphine was given if visual analogic scale (VAS) for pain was > or = 4 (scale 0-10) and metoclopramide was administered if a patient presented > or = 2 PONV episodes (nausea or vomiting) in less than 30 min. Postoperatively (2, 12 and 24 h), we registered VAS, rescue morphine consumption, number of patients with episodes of PONV and number of patients requiring metoclopramide. P < 0.05 was considered significant.

RESULTS

There were no significant differences between groups in the demographic parameters, ASA physical status, propofol dose, VAS, and rescue morphine requirements. Fourteen patients in the fentanyl group and four in the remifentanil group presented PONV episodes 2-12 h postoperative hours' interval; (P < 0.05). Ten patients in the fentanyl group and four in the remifentanil group presented vomiting episodes in the same period (P < 0.05); and eight patients in the fentanyl group and one in the remifentanil group required metoclopramide; (P < 0.05). The number of postoperative PONV episodes were low, both in the 0-2-h period (n = 2 vs. n = 1, fentanyl and remifentanil, respectively) and in the 12-24-h period (n = 3 vs. n = 1).

CONCLUSION

Propofol + fentanyl anaesthesia resulted in a higher incidence of PONV and requirements of antiemetic drugs in the period between 2 and 12 postoperative hours compared with propofol + remifentanil, in patients undergoing plastic surgery.

The Use of Ultra-Short-Acting Opioids in Paediatric Anaesthesia

Remifentanil is a synthetic opioid that was developed in the early 1990s and introduced into clinical use in 1996. It is a methyl ester and is metabolised by nonspecific tissue and plasma esterases. Consequently, it is a drug that undergoes rapid elimination and has a reported terminal elimination half-life of between 10 and 35 minutes. Because there is no drug accumulation, the context-sensitive half-time remains constant; thus the pharmacokinetics of the drug do not change regardless of the duration of infusion. The organ-independent elimination of remifentanil, coupled with the fact that its clearance is greater in infants and neonates compared with older age groups, make its pharmacokinetic profile different from any other opioid. In addition, its unique metabolism confers predictability in its clinical use. Like other opioid mu receptor agonists, remifentanil provides dose-dependent analgesia, while the adverse effects of this drug, e.g. respiratory depression, are also thought to be dose related. The incidence of nausea and vomiting appear similar to other opioids. Its rapid and consistent metabolism regardless of duration of infusion has made remifentanil an attractive analgesic/anaesthetic option for paediatric care providers.

Remifentanil: an update

PURPOSE OF REVIEW

Remifentanil has now reached maturity, as reflected by the increasing number of clinical papers relating to its use. Its position among anaesthetic drugs is now better understood, and this review will attempt to place it in the context of current clinical practice.

RECENT FINDINGS AND SUMMARY

Propofol reduces the initial distribution of remifentanil, leading to higher concentrations during induction. Propofol and remifentanil administered together at sedative doses display a major synergistic interaction on the respiratory drive. Remifentanil accelerates the penetration of sevoflurane to its site of effect. The risk of intraoperative awareness seems to be low when remifentanil is associated to very low concentrations of hypnotic drugs, but this field warrants further investigation. Acute tolerance to opioids and its prevention remain controversial.

SUMMARY

Remifentanil is the opioid of choice for tracheal intubation without muscle relaxants. It provides an alternative to regional anaesthesia in labour pain control. Target-controlled infusion may further improve the administration of remifentanil.

Pain management for pediatric ambulatory anesthesia

PURPOSE OF REVIEW

New developments in analgesic drugs and techniques are being applied to the pediatric population. Appropriate pain management for ambulatory surgery patients helps to facilitate early discharge and minimize postoperative morbidity.

RECENT FINDINGS

A variety of opioid-related drugs, as well as novel delivery routes for opioids, have been reported in the pediatric population. New pharmacokinetic information for acetaminophen has resulted in revised dosage recommendations; applications of the nonsteroidal antiinflammatory agents are also discussed. Furthermore, regional anesthesia and adjuncts are useful in the pediatric ambulatory surgery patient.

SUMMARY

Recent data on techniques for pain management after pediatric ambulatory surgery will help the anesthetist develop a comprehensive plan for the postoperative period.