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

Short-acting versus long-acting opioids for pediatric postoperative pain management

INTRODUCTION

Opioids are potent analgesics commonly used to manage children's moderate to severe perioperative pain in children. A wide range of short and long-acting opioids are used to treat surgical pain and will be reviewed in this article.

AREAS COVERED

Both short- and long-acting opioids contain unique therapeutic benefits and adverse effects; however, due to the side effect profile and safety concerns, lack of familiarity, and evidence with long-acting opioids to treat surgical pain, shorter-acting opioids have traditionally been used in children. Almost all opioids work by binding to the mu receptor. Methadone, a long-acting opioid, is an exception because it also has beneficial N-methyl-D-aspartate antagonist properties. Clinically methadone's properties could translate to improved analgesic outcomes, reduced risk of adverse events, less risk for acute hyperalgesia, tolerance and abuse potential, faster recovery, and reduced risk for chronic persistent surgical pain. This review article summarizes and compares the evidence of commonly used short and long-acting opioids for perioperative pain control in the pediatric population.

EXPERT OPINION

Individualized methadone therapy using pharmacogenomics has the potential to transform opioid use in pain management by improving patient safety and analgesic outcomes, thereby addressing the gaps in current standardized ERAS protocols.

Analgesic Efficacy of Erector Spinae Plane Block in Pediatric Abdominal Surgery: Guidance with Conventional Method and NOL: Case Series

Background

Erector spinae plane (ESP) block is a regional anesthesia technique that blocks both somatic and visceral nerve fibers. Despite its high analgesic potential, its mechanism of action is not yet fully understood. The ultrasound-guided ESP block, which can be easily performed, makes important contributions to the control of intraoperative pain in pediatric patients undergoing abdominal surgery. The follow-up of pain in the intraoperative period is usually done by evaluating the changes in hemodynamic parameters. Due to physiological differences in pediatric patients, it is more difficult to do this with only hemodynamic changes than in adult patients. Aim: The NOL® (Nociception Level) monitor calculates the nociception/pain score by evaluating many parameters through a proprietary algorithm. Our primary aim was to demonstrate the effectiveness of ESP block with an advanced pain monitor in this patient group; our secondary aim was to investigate the necessity of pain monitors in the pediatric patient group.

Methods

In this case series, we applied intraoperative NOL® monitoring in addition to standard monitoring (ECG, SpO2, heart rate, EtCO₂) in pediatric patients (16 cases) who were scheduled for abdominal surgery and underwent ESP block.

Results

Considering the hemodynamic data, NOL values, postoperative pain scores, side effects, and complications, it was concluded that ESP block can be used safely in this patient group. Although the hemodynamic data and the NOL® index were compatible with each other after a nociceptive stimulus, the NOL index was less affected by other variables and gave the clinician clearer information about pain.

Pharmacokinetics of Fentanyl and Its Derivatives in Children: A Comprehensive Review

Fentanyl and its derivatives sufentanil, alfentanil, and remifentanil are potent opioids. A comprehensive review of the use of fentanyl and its derivatives in the pediatric population was performed using the National Library of Medicine PubMed. Studies were included if they contained original pharmacokinetic parameters or models using established routes of administration in patients younger than 18 years of age. Of 372 retrieved articles, 44 eligible pharmacokinetic studies contained data of 821 patients younger than 18 years of age, including more than 46 preterm infants, 64 full-term neonates, 115 infants/toddlers, 188 children, and 28 adolescents. Underlying diagnoses included congenital heart and pulmonary disease and abdominal disorders. Routes of drug administration were intravenous, epidural, oral-transmucosal, intranasal, and transdermal. Despite extensive use in daily clinical practice, few studies have been performed. Preterm and term infants have lower clearance and protein binding. Pharmacokinetics was not altered by chronic renal or hepatic disease. Analyses of the pooled individual patients' data revealed that clearance maturation relating to body weight could be best described by the Hill function for sufentanil (R ² = 0.71, B _max 876 mL/min, K ₅₀ 16.3 kg) and alfentanil (R ² = 0.70, B _{max (fixed)} 420 mL/min, K ₅₀ 28 kg). The allometric exponent for estimation of clearance of sufentanil was 0.99 and 0.75 for alfentanil clearance. Maturation of remifentanil clearance was described by linear regression to bodyweight (R ² = 0.69). The allometric exponent for estimation of remifentanil clearance was 0.76. For fentanyl, linear regression showed only a weak correlation between clearance and bodyweight in preterm and term neonates (R ² = 0.22) owing to a lack of data in older age groups. A large heterogeneity regarding study design, clinical setting, drug administration, laboratory assays, and pharmacokinetic estimation was observed between studies introducing bias into the analyses performed in this review. A limitation of this review is that pharmacokinetic data, based on different modes of administration, dosing schemes, and parameter estimation methods, were combined.

Population Pharmacokinetic Modeling of Remifentanil in Infants with Unrepaired Tetralogy of Fallot

BACKGROUND

Although there is literature suggesting that pathophysiologic changes in children with congenital heart disease alter the pharmacokinetics of anesthetics and may result in dosage adjustment, limited information exists regarding the pharmacokinetics of remifentanil in infants with unrepaired tetralogy of Fallot (TOF). The objectives of the current analysis were to characterize the population pharmacokinetics of remifentanil in infants, and to evaluate the effects of TOF on remifentanil's pharmacokinetics.

METHODS

Twenty-seven infants (16 with TOF and 11 with normal cardiac anatomy; aged 114-360 days) scheduled to undergo elective surgery under general anesthesia were recruited in the study. All children received remifentanil 1 μg/kg/min intravenously for anesthesia induction and early maintenance [until ~ 20 min before cardiopulmonary bypass (CPB) for patients with TOF]. Serial arterial blood samples were drawn and analyzed. Population pharmacokinetics of remifentanil was characterized using NONMEM software. The estimates were standardized to a 70-kg adult using a per-kilogram model.

RESULTS

A two-compartment disposition model adequately described the pharmacokinetics of remifentanil. Besides body weight, the introduction of any other covariates, including TOF status, did not improve the model significantly (P > 0.05). The population parameter estimates for systemic clearance (Cl₁) and inter-compartment clearances (Cl₂) were 6.03 × (WT/70 kg) and 1.23 × (WT/70 kg) L/min, respectively, and central volume of distribution (V₁) and peripheral volumes of distribution (V₂) were 19.6 × (WT/70 kg) and 21.7 × (WT/70 kg) L, respectively.

CONCLUSIONS

Unrepaired TOF does not change the pharmacokinetics of remifentanil, suggesting a similar dosage for infants with TOF compared to normal cardiac anatomy infants.

CLINICAL TRIAL REGISTRATION

The patient enrollment in this study started at 2012, so we do not have clinic trial number, but we still think this is a valuable research and hope it could be considered for publication.

Correction to: Pharmacokinetics of Fentanyl and Its Derivatives in Children: A Comprehensive Review

Fentanyl and its derivatives sufentanil, alfentanil, and remifentanil are potent opioids. A comprehensive review of the use of fentanyl and its derivatives in the pediatric population was performed using the National Library of Medicine PubMed. Studies were included if they contained original pharmacokinetic parameters or models using established routes of administration in patients younger than 18 years of age. Of 372 retrieved articles, 44 eligible pharmacokinetic studies contained data of 821 patients younger than 18 years of age, including more than 46 preterm infants, 64 full-term neonates, 115 infants/toddlers, 188 children, and 28 adolescents. Underlying diagnoses included congenital heart and pulmonary disease and abdominal disorders. Routes of drug administration were intravenous, epidural, oral-transmucosal, intranasal, and transdermal. Despite extensive use in daily clinical practice, few studies have been performed. Preterm and term infants have lower clearance and protein binding. Pharmacokinetics was not altered by chronic renal or hepatic disease. Analyses of the pooled individual patients' data revealed that clearance maturation relating to body weight could be best described by the Hill function for sufentanil (R ² = 0.71, B _max 876 mL/min, K ₅₀ 16.3 kg) and alfentanil (R ² = 0.70, B _{max (fixed)} 420 mL/min, K ₅₀ 28 kg). The allometric exponent for estimation of clearance of sufentanil was 0.99 and 0.75 for alfentanil clearance. Maturation of remifentanil clearance was described by linear regression to bodyweight (R ² = 0.69). The allometric exponent for estimation of remifentanil clearance was 0.76. For fentanyl, linear regression showed only a weak correlation between clearance and bodyweight in preterm and term neonates (R ² = 0.22) owing to a lack of data in older age groups. A large heterogeneity regarding study design, clinical setting, drug administration, laboratory assays, and pharmacokinetic estimation was observed between studies introducing bias into the analyses performed in this review. A limitation of this review is that pharmacokinetic data, based on different modes of administration, dosing schemes, and parameter estimation methods, were combined.

Screening of stabilizers for LC–MS/MS analysis of clevidipine and its primary metabolite in dog whole blood

Background: Clevidipine is an ester-containing antihypertensive agent that undergoes rapid hydrolysis in blood. A reliable stabilizer cocktail containing citric acid and ascorbic acid was established and the LC–MS/MS method was validated for simultaneous determination of clevidipine and its major metabolite in beagle dog whole blood. Results: The stabilizer could nearly completely inhibit the esterase activity. Both analytes were extracted from whole blood by toluene and detected by MS/MS in positive ESI mode. The linearity range was 0.1–100.0 ng/ml for clevidipine and 1.0–1000.0 ng/ml for the primary metabolite. Conclusion: The stabilizer cocktail was able to effectively suppress the activity of esterase in blood. The method was successfully applied to a PK study of clevidipine in beagle dogs.

A comparative study of two remifentanil doses for procedural pain in ventilated preterm infants: a randomized, controlled study*

OBJECTIVES

Remifentanil is an ultrashort-acting synthetic opioid, and the metabolism of which is not influenced by hepatic or renal function. This study aims to compare the efficacy of two remifentanil doses during procedures in ventilated preterm infants.

DESIGN

Prospective, randomized, double-blind, noninferiority trial.

SETTING

Neonatal ICU.

PATIENTS

Preterm infants who were supported by a mechanical ventilator with tracheal tube and requiring central venous access.

INTERVENTIONS

Two remifentanil dosages were administered in mechanically ventilated preterm infants during peripherally inserted central catheter insertion. Fourteen preterm infants were randomly assigned to low-dose (0.1 μg/kg/min) or high-dose (0.25 μg/kg/min) remifentanil infusion. The Premature Infant Pain Profile was used to score pain during the procedure, and changes in the Premature Infant Pain Profile score between needle puncture and baseline were analyzed to investigate the noninferiority of low-dose to high-dose remifentanil. Occurrence of cardiorespiratory complications was also recorded.

MEASUREMENTS AND MAIN RESULTS

The median gestational age (minimum, maximum) was 26 weeks (24, 31), and the median birth weight was 825 g (610, 1,280). Changes in Premature Infant Pain Profile in the high-dose and low-dose groups were 1.43 ± 3.10 and -0.60 ± 5.32, respectively. The difference in changes in the Premature Infant Pain Profile score between the high-dose and low-dose groups was -2.03 ± 4.13. The corresponding lower limit of one-tailed 97.5% CI was -7.24, below the noninferiority margin. Apneic events and bradycardia did not occur in the low-dose group; however, there were three episodes of apnea (42.9%) and one of bradycardia (14.3%) in the high-dose group (p = 0.683 and 0.366, respectively).

CONCLUSION

For mechanically ventilated preterm infants, the use of remifentanil at 0.25 μg/kg/min as an analgesic for short procedures represents a therapeutic option. Our pilot study suggests the need for larger randomized trials.

Sedation of newborn infants for the INSURE procedure, are we sure?

Background. Neonatal intubation is a stressful procedure that requires premedication to improve intubation conditions and reduce stress and adverse physiological responses. Premedication used during the INSURE (INtubation, SURfactant therapy, Extubation) procedure should have a very short duration of action with restoration of spontaneous breathing within a few minutes. Aims. To determine the best sedative for intubation during the INSURE procedure by systematic review of the literature. Methods. We reviewed all relevant studies reporting on premedication, distress, and time to restoration of spontaneous breathing during the INSURE procedure. Results. This review included 12 studies: two relatively small studies explicitly evaluated the effect of premedication (propofol and remifentanil) during the INSURE procedure, both showing good intubation conditions and an average extubation time of about 20 minutes. Ten studies reporting on fentanyl or morphine provided insufficient information about these items. Conclusions. Too little is known in the literature to draw a solid conclusion on which premedication could be best used during the INSURE procedure. Both remifentanil and propofol are suitable candidates but dose-finding studies to detect effective nontoxic doses in newborns with different gestational ages are necessary.

Remifentanil versus fentanyl for esophagogastroduodenoscopy in children

OBJECTIVES

We compared sedation by propofol combined with either fentanyl or remifentanil in pediatric outpatients undergoing diagnostic esophagogastroduodenoscopy.

PATIENTS AND METHODS

Forty-two children scheduled for esophagogastroduodenoscopy in our institution were randomly assigned to receive 2 mg/kg propofol plus either 1 μg/kg bolus of fentanyl (group F; n = 20) or 0.5 μg/kg bolus of remifentanil (group R; n = 22). Cardiorespiratory parameters, sedation level, adverse effects related to the drugs and/or to the procedure, ease of performance for the endoscopist, and time to awakening were analyzed.

RESULTS

There were no clinically significant changes in hemodynamics. Apnea periods >20 seconds and decreases in SaO2 <90% occurred more frequently in group R (31.8% vs 0%, P < 0.01, and 27.3% vs 5.0%, P > 0.05, respectively). Children in group R had significantly shorter average time to awakening: 9.5 ± 5.6 vs 16.5 ± 10.5 minutes (P = 0.01), and received a significantly lower total dose of propofol (P = 0.034). Adverse effects within the first 24 hours postprocedure occurred less frequently in group R (P = 0.03).

CONCLUSIONS

Remifentanil in combination with propofol provides good analgesic and sedative effects, which were shorter lasting compared with fentanyl-based sedation, and caused fewer delayed adverse effects. The use of remifentanil was associated with respiratory depression, emphasizing the need for experienced anesthesiologists.

[Diagnostic and interventional operations in childhood: anesthesiology management]

Diagnostic and interventional procedures in children often need to be performed under sedation. This prevents pain and stress in children and provides optimal examination conditions. For complete immobilization and stress shielding the depth of sedation often corresponds with general anesthesia. Therefore, established safety standards need to be observed and a fundamental precondition is implementation by a skilled anesthesiologist who can handle the anesthesiology procedure and its possible complications. Organization, schedule, medication, equipment, monitoring and post-anesthesiology care should be institutionally defined. A professional anesthesiology management of pediatric patients is an important factor to increase the quality of care, patient safety and patient satisfaction.

Remifentanil in neonatal intensive care and anaesthesia practice

Remifentanil is a relatively new ultrashort action synthetic opioid. Studies on the use of remifentanil in neonatology have emerged demonstrating its effectiveness and safety in neonates. The present study describes the use of remifentanil in both full-term and premature newborns, highlighting the theoretical benefits for this population in terms of both neonatal intensive care and anaesthesia. A Medline search was undertaken of all reviews and reports about the use of remifentanil in neonates published between 1996 and 2009 using MeSH search terms 'remifentanil', 'analgesia', 'anaesthesia', 'newborn' and 'neonate'. The review points that remifentanil has been used with advantages in newborns including preterm neonates and even for foetal anaesthesia. It proved to be a good option to attenuate the hemodynamic/endocrine markers of stress related to surgery. Owing to its unique pharmacokinetic profile, shorter extubation times can be achieved what makes the drug also a good option for short duration invasive procedures in NICUs (InSurE). A concern on its use is that the hemodynamic response (hypotension) may become significant when the drug is associated to other drugs like sevoflurane.

CONCLUSION

Remifentanil seems to be an effective and safely used opioid for neonatal intensive care and anaesthesia practice.

Remifentanil infusion as a modality for opioid-based anaesthesia in paediatric practice

This study was designed to compare the intra-operative and post-operative analgesic requirements and side effects of using fentanyl infusion versus remifentanil infusion during short-duration surgical procedures in children. The study comprised of 40 children randomly allocated into two equal groups: fentanyl (F-group) or remifentanil (R-group). Both were administered a continuous intravenous (i.v.) infusion. Anaesthetic recovery was assessed using the Brussels sedation scale every 5 min from the time of entry till discharge from recovery room. Post-operative analgesia was assessed throughout the first three post-operative (PO) hours using observational pain–discomfort scale (OPS) and adverse events were recorded. Haemodynamic variables showed a non-significant difference between both the groups. Patients who received remifentanil showed significantly shorter time to spontaneous respiration, eye opening, extubation and verbalization compared to those who received fentanyl. Discharge time was significantly shorter in R-group, and 18 patients fulfilled criteria for recovery-room discharge at ≤25 min with a significant difference in favour of remifentanil. Fentanyl provided significantly better PO analgesia than remifentanil and children in F-group showed a significantly lower mean cumulative OPS record than those in R-group; however, the number of patients requiring rescue analgesia did not show a significant difference between both the groups. Two cases in F-group and one in R-group had bradycardia, one case in R-group had mild hypotension and PO vomiting had occurred in three patients in the F-group and two patients in the R-group. In conclusion, remifentanil is appropriate for opioid-based anaesthesia for paediatric patients as it provides haemodynamic stability and rapid recovery with minimal post-operative side effects.

Dose of remifentanil for minimizing the cardiovascular changes to tracheal intubation in pediatric patients

Background

The purpose of this study was to investigate a dosage of remifentanil for attenuating cardiovascular changes during anesthetic induction in pediatric anesthesia.

Methods

We examined the effect of remifentanil on the cardiovascular responses to intubation in 90 children ASA 1 patients, aged 4-15 years, randomly allocated to receive 1.0 ug/kg remifentanil as a bolus (R 1), or 1.5 ug/kg remifentanil (R 1.5), or 2.0 ug/kg remifentanil (R 2). Before induction, IV midazolam 0.05 mg/kg was given for sedation. After glycoppylorate 5 ug/kg, thiopental 4.0 mg/kg was injected within 10 seconds and followed by remifentanil. Following check the unconsciousness, patients were received rocuronium 0.6 mg/kg and tracheal intubation were performed 90s later, and anesthesia was maintained with 2% sevoflurane in air/oxygen. Systolic arterial pressure (SAP), mean arterial pressure (MAP) and heart rate (HR) were measured at before induction of anesthesia (B), before, just after and at 1, and 3 minutes after tracheal intubation.

Results

SAP and HR were increased than B values in the three groups just after intubation (P < 0.05). The percentage increases of SAP and HR were 30% and 30% of B values, respectively, in R 1; 19% and 24% in R 1.5; 10% and 22% in R 2. There were significant differences between R 2 group and other two groups in SAP and HR (P < 0.05).

Conclusions

In pediatric anesthesia, a bolus injection of 2 ug/kg remifentanil (R 2) was a dosage to attenuate the cardiovascular responses after intubation in pediatric patients.

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.

Remifentanil in children

Remifentanil has gained the confidence of anesthesiologists and has given a real opportunity to change the way anesthesia is given. It can be considered the ideal opioid despite many obstacles to pediatric use: the condition of 'off-label', the lack of wide randomized clinical trials, and the fear of adverse events because of its high potency. Experiences in the field with this opioid over the years encouraged its use. Use has been associated with N(2)0 and volatile agents for general anesthesia and with propofol for total intravenous anesthesia (TIVA). It seems very useful for sedation inside and outside the operating room and in intensive care for both short painful procedures and synchronization with mechanical ventilation. However, its unique pharmacokinetic characteristics causing rapid onset and offset of effect appear unchanged in small children and even in premature neonates and need to be really confirmed by further pharmacokinetic studies. Moreover, the real risks of tolerance and hyperalgesia should be evaluated in the pediatric population. In this review, we go through the newer aspects of this versatile drug that has been proposed as 'the pediatric anesthetist's opiate'.

Effect of different anesthetic agents on oculocardiac reflex in pediatric strabismus surgery

PURPOSE

The oculocardiac reflex (OCR) occurs frequently during pediatric strabismus surgery. The aim of this study was to assess the effects of various anesthetic regimens on the incidence of OCR during the surgery.

METHODS

Two hundred and eighty children, 1 to 9 years old, undergoing elective strabismus surgery, were randomly assigned to eight groups; ketamine-sevoflurane (KS), ketamine-desflurane (KD), ketamine-propofol (KP), ketamine-remifentanil (KR), midazolam-sevoflurane (MS), midazolam-desflurane (MD), midazolam-propofol (MP), and midazolam-remifentanil (MR). No premedication was given. Anesthesia was induced using ketamine 1 mg kg(-1) or midazolam 0.15 mg kg(-1) with 66% N(2)O in O(2). Laryngeal mask airways (LMAs) were placed with rocuronium 0.5 mg kg(-1). Anesthesia was maintained with sevoflurane 2-3 vol. %, desflurane 5-6 vol. %, propofol 7-8 mg kg(-1) h(-1), or remifentanil 0.75 microg kg(-1) over 1 min, followed by a continuous infusion of remifentanil 0.5 microg kg(-1) min(-1) with 66% N(2)O in O(2). Heart rate (HR) was recorded during extraocular muscle (EOM) manipulation. OCR was defined as a reduction in HR of more than 20% induced by the traction of an EOM.

RESULTS

In patients given ketamine, OCR occurred more frequently in the KP (65.7%) and KR (62.9%) groups than in the KD (29.4%) and KS (37.1%) groups (P < 0.05). In patients given midazolam, OCR occurred more frequently in the MP (54.3%) and MR (60.6%) groups than in the MD (36.4%) and MS (31.4%) groups (P < 0.05).

CONCLUSION

Propofol or remifentanil anesthesia was associated with a higher incidence of OCR during pediatric strabismus surgery than sevoflurane and desflurane anesthesia, when either ketamine or midazolam was used as an induction agent.

Remifentanil analgosedation in preterm newborns during mechanical ventilation

AIM

To assess efficacy of remifentanil in preterm newborns during mechanical ventilation.

METHODS

Remifentanil was administered by continuous intravenous infusion to provide analgesia and sedation in 48 preterm infants who developed respiratory distress and required mechanical ventilation. We examined the doses needed to provide adequate analgesia, extubation time after the discontinuation of opioid infusion, the presence of side effects and safety of the use.

RESULTS

Remifentanil provided adequate analgesia, with a significant reduction of NIPS and COMFORT score since 1 h after starting the infusion of remifentanil. The drug was initially administered at a dose of 0.075 microg/kg/min, but in 73% of newborns the latter had to be increased; at a dose of 0.094 +/- 0.03 (mean +/- standard deviation) microg/kg/min, 97% of the newborns received adequate analgesia and sedation. The time elapsed between the discontinuation of remifentanil infusion and extubation was 36 +/- 12 min. Treatment was started between the 1st and the 17th day of life. The mean duration of therapy was 5.9 +/- 5.7 days. No side effects on the respiratory or cardiovascular system were observed.

CONCLUSION

Remifentanil is a manageable and effective opioid in the newborn undergoing mechanical ventilation, though randomized controlled trials and information about long-term outcomes are necessary.

Bolus dose remifentanil and sufentanil blunting cardiovascular intubation responses in children: a randomized, double-blind comparison

BACKGROUND AND OBJECTIVE

The present randomized controlled study was designed to compare the efficacy of remifentanil 2 microg kg(-1) and sufentanil 0.2 microg kg(-1) by bolus injection on the cardiovascular response to intubation in healthy children.

METHODS

One hundred and five children, ASA 1-2 and scheduled for elective plastic surgery under general anaesthesia, were randomly divided into one of two study groups to receive the following treatments in a double-blind manner: remifentanil 2 microg kg(-1) (group R) and sufentanil 0.2 microg kg(-1) (group S). Blood pressure and heart rate (HR) were recorded before anaesthesia induction (baseline values), immediately before intubation (postinduction values), at intubation and every minute for 5 min after intubation. The percentage changes in systolic blood pressure (SBP) and HR relative to baseline values were calculated. The incidences of SBP and HR percentage changes of more than 30% of baseline values during the observation were recorded.

RESULTS

As compared with baseline values, blood pressure and HR at intubation and their maximum values during the observation increased significantly in group S, but decreased significantly in group R. Blood pressure and HR at intubation and their maximum values during the observation were significantly different between the groups. There were significant differences between the groups in the percentage changes of SBP and HR relative to baseline values and their maximum percentage changes during the observation. The incidences of SBP and HR percentage increases of more than 30% of baseline values were not significantly different between the groups, but the incidences of SBP and HR percentage decreases of more than 30% of baseline values were significantly higher in group R than in group S.

CONCLUSION

In combination with propofol for anaesthesia induction in children, sufentanil 0.2 microg kg(-1) by bolus injection fails to depress the cardiovascular intubation response. Remifentanil 2 microg kg(-1) by bolus injection can completely abolish the cardiovascular intubation response, but causes more adverse cardiovascular depression.

Different small-dose remifentanil blunting the cardiovascular response to laryngoscopy and intubation in children: a randomized double-blind comparison

BACKGROUND

The available data provide inconsistent results on the efficacy of small-dose remifentanil attenuating the cardiovascular response to intubation in children. Therefore, this randomized double-blind study was designed to assess the ability of different small doses of remifentanil on the cardiovascular intubation response in children, with the aim of determining the optimal dose of remifentanil for this purpose.

METHODS

One hundred and twenty-four children aged 3-9 yr were randomized to one of four groups to receive the following in a double-blind manner: normal saline (Group 1), remifentanil 0.75 microg kg(-1) (Group 2), remifentanil 1 microg kg(-1) (Group 3) and remifentanil 1.25 microg kg(-1) (Group 4). Non-invasive blood pressure and heart rate were recorded before anaesthesia induction (baseline value), immediately before intubation (postinduction values), at intubation and at 1 min intervals for 5 min after intubation.

RESULTS

Tracheal intubation caused significant increases in systolic blood pressure and heart rate in Groups 1-3 compared with the baseline values. The maximum percent increases of systolic blood pressure and heart rate were 10% and 26% of the baseline values, respectively, in Group 2; 5% and 14% in Group 3; and 1% and 8% in Group 4 compared with 27% and 37% in Group 1. Except for the Group 3 vs. Group 4 comparison, there were significant differences among the four groups in the maximum percent increases of systolic blood pressure and heart rate.

CONCLUSIONS

When used as part of anaesthesia induction with propofol and vecuronium in children, bolus administration of remifentanil resulted in a dose-related attenuation of the cardiovascular intubation response.