Plasma levels of clonidine following epidural bolus injection in children

Caudal Block versus Wound Infiltration for Inguinal Procedures in Young Children: A Randomized Clinical Study

INTRODUCTION

 Inguinal procedures in children are frequent and typically performed in an outpatient setting. We aimed to analyze whether there is a difference in postoperative pain scores and setup time (start of anesthesia management to incision time) when comparing caudal block (CB) with local wound infiltration.

MATERIALS AND METHODS

 We enrolled pediatric outpatients scheduled for inguinal procedures. Patients were randomized to receive either preincision CBs or end-of-procedure local wound infiltration. Postoperative pain scores until 24 hours postoperatively and setup time were analyzed.

RESULTS

 Fifty-two patients were included in the study. Thirty patients received a CB, and 22 patients received local infiltration (LI). There was no significant difference in postoperative pain scores. Setup time was significantly higher in the CB group: median 22.5 minutes IQR (16-46 minutes) compared with 17 minutes in the LI group IQR (10-35 minutes), p-value of 0.0026.

CONCLUSION

 Both CB and LI result in good postoperative pain control after inguinal procedures in pediatric outpatients. Since LI is less time consuming and has lower risks for complications, we recommend this technique for inguinal procedures in pediatric outpatients. Our findings will need to be confirmed in larger cohorts, but we believe the evidence generated with this study has the potential to positively influence patient care, operating room efficiency, and costs.

Postoperative Analgesia in Neonates and Infants Using Epidural Chloroprocaine and Clonidine

INTRODUCTION

In neonates and infants, epidural analgesia has gained popularity as a means of providing postoperative analgesia, limiting opioid-related adverse effects and improving the postoperative course. In addition to a local anesthetic agent, adjunctive agents may be added to further augment analgesia. Clonidine is an α2-adrenergic agonist that is frequently added to single-shot caudal analgesia, but there are limited data regarding its use in a continuous epidural infusion, especially in patients ≤12 months of age.

METHODS

We retrospectively reviewed the hospital records of neonates and infants who received postoperative epidural infusions with 2-chloroprocaine, and clonidine was identified over a 4-year period.

RESULTS

The study cohort included 52 neonates and infants ranging in age from 0 to 12 months and in weight from 2.1 to 10.1 kilograms. The catheters were dosed with either 1.5% 2-chloroprocaine (n=47) or 3% 2-chloroprocaine (n=5) with clonidine (median concentration 0.2 µg/mL) infused at a median rate of 0.72 mL/kg/hour. Pain scores were uniformly ≤3 at all evaluation points during the first 72 postoperative hours with a limited need for supplemental systemic opioids. No serious adverse effects were noted.

CONCLUSION

With the recognized limitations of a retrospective study, these preliminary data demonstrate the safety of adding clonidine to an epidural infusion of 2-chloroprocaine in neonates and infants less than 12 months of age. Future studies are needed to determine its analgesic efficacy compared to 2-chloroprocaine alone and the optimal clonidine concentration for postoperative epidural infusions.

Pharmacokinetics of an intravenous bolus dose of clonidine in children undergoing surgery

BACKGROUND

Clonidine is used off-label in children but only limited pediatric pharmacokinetic data are available for intravenously administered clonidine.

OBJECTIVES

To determine pharmacokinetic parameter estimates of clonidine in healthy children undergoing surgery and to investigate age-related differences. Furthermore, to investigate possible pharmacokinetic differences of clonidine between this group of children and a cohort with cardiac diseases.

METHODS

In a randomized placebo-controlled trial (The PREVENT AGITATION trial), blood samples for clonidine pharmacokinetic analysis were collected in a proportion of the enrolled patients. Healthy children with ASA score 1-2 in the age-groups 1 to <2 years and 2-5 years were randomized for blood sampling. Clonidine was administered as a single intravenous bolus of 3 µg/kg intraoperatively. Blood samples were drawn at baseline, 5, 10, 15, 30, 60 minutes after dosing and additionally every hour until discharge from the PACU. Clonidine analysis was performed on liquid chromatography-mass spectrometry.

RESULTS

Data form eighteen children were available for pharmacokinetic analysis (ASA I; male/female: 17/1; age: 1-5 years; weight 8.7-24 kg). Population parameter estimates for the 2-compartment model were similar to previous published data for children who underwent cardiac surgery. A pooled analysis including data from 59 children indicated clearance of 14.4 L h^-1  70 kg^-1 and volume of distribution of 192.6 L 70 kg^-1 . No age-related pharmacokinetic differences and no difference in time from administration of study medication to awakening were found. Children 1 to <2 years had a shorter PACU stay than children 2-5 years (mean difference 17% 95% CI:3%-34%, P = .02).

CONCLUSION

Pharmacokinetic parameter estimates were similar for children undergoing general surgery and cardiac surgery given a single dose of intravenous clonidine. These results indicated that no dose reduction is needed in children aged 1 to <2 years compared with those 2-5 years, which was supported by pharmacodynamic observations.

Optimizing clonidine dosage for sedation in mechanically ventilated children: A pharmacokinetic simulation study

BACKGROUND

Clonidine is in widespread off-label use as a sedative in mechanically ventilated children, despite limited evidence of efficacy. A variety of dosage regimens have been utilized in clinical practice and in research studies. Within these studies, clonidine has inconsistently shown useful sedation properties. One of the reasons attributed to the inconsistent signs of efficacy is suboptimal clonidine dosing.

AIMS

This study aims to propose a target plasma concentration and simulate clonidine pharmacokinetics (PK) in a cohort of mechanically ventilated children to evaluate the adequacy of clonidine dosage regimens used in clinical practice and research studies.

METHODS

A literature search was undertaken to identify a clonidine pharmaockinetic-pharmacodynamics (PKPD) model, from which a target concentration for sedation was defined. Using a previously published PK model, the projected plasma concentrations of 692 mechanically ventilated children (demographics taken from a recent study) were generated. Doses from recently published clinical studies were investigated. Adequacy of each regimen to attain therapeutic clonidine plasma concentrations was assessed.

RESULTS

A target plasma concentration of above 2 µg/L was proposed. Nine dosage regimens (four intravenous boluses, four intravenous infusions, and one nasogastric route boluses) were evaluated ranging from 1 µg/kg eight hourly intravenous boluses to a regimen up to 3 µg/kg/hr continuous intravenous infusion. Regimens with a loading dose of 2 µg/kg followed by variable continuous infusion of up to 2 µg/kg/hr titrated according to sedation score appear most suitable. Doses should be halved in neonates.

CONCLUSION

The variety of dosage regimens in the previous studies of clonidine along with difficulties in the conduct of interventional studies may have contributed to the lack of efficacy data to support its use. Simulations of clonidine plasma concentrations based on known population pharmacokinetic parameters suggest a loading dose followed by higher than current practice maintenance dose infusion is required to achieve adequate steady-state concentrations early in treatment. Further PKPD studies will aid in the determination of the optimal clonidine dosage regimen.

Role of Clonidine in Neonatal Abstinence Syndrome

Objective: To provide a systematic review of the current role of clonidine in neonatal abstinence syndrome (NAS). Data Sources: A MEDLINE literature search inclusive of the dates 1946 to November 2015 was performed using the search terms clonidine and abstinence syndromes, neonatal. Excerpta Medica was searched from 1980 to November 2015 using the search terms clonidine and newborn. Additionally, Web of Science was searched using the terms clonidine and neon* inclusive of 1945 to November 2015. Study Selection and Data Extraction: We utilized the PRISMA guidelines to select English language, human primary literature, review articles, and supporting data assessing the efficacy of clonidine in the treatment of NAS. Data Synthesis: Three clinical trials and 5 observational studies demonstrated evidence of clonidine’s effectiveness in NAS. Clonidine’s therapeutic use as monotherapy and in combination with other agents was shown to reduce the time needed for pharmacotherapy treatment. Adverse reactions associated with clonidine in neonates, when reported, are mild. Conclusion: The American Academy of Pediatrics recommends opioids as first-line agents in the treatment of NAS when pharmacological treatment is indicated. Limited data suggest that clonidine, in combination with other agents or as monotherapy, may be as effective, with minimal adverse effects and reduced treatment time. Prospective clinical trials are necessary to clarify the ultimate role of clonidine in NAS and establish long-term safety.

Adjuncts should always be used in pediatric regional anesthesia

A number of different adjuncts to local anesthetics can be used to prolong and optimize postoperative pain relief following regional anesthesia in children. The present text provides a slightly opinionated but evidence-based argument in favor of this practice.

Individual and population pharmacokinetic compartment analysis: a graphic procedure for quantification of predictive performance

Objectives

Pharmacokinetic studies are important for optimizing of drug dosing, but requires proper validation of the used pharmacokinetic procedures. However, simple and reliable statistical methods suitable for evaluation of the predictive performance of pharmacokinetic analysis are essentially lacking. The aim of the present study was to construct and evaluate a graphic procedure for quantification of predictive performance of individual and population pharmacokinetic compartment analysis.

Methods

Original data from previously published pharmacokinetic compartment analyses after intravenous, oral, and epidural administration, and digitized data, obtained from published scatter plots of observed vs predicted drug concentrations from population pharmacokinetic studies using the NPEM algorithm and NONMEM computer program and Bayesian forecasting procedures, were used for estimating the predictive performance according to the proposed graphical method and by the method of Sheiner and Beal.

Results

The graphical plot proposed in the present paper proved to be a useful tool for evaluation of predictive performance of both individual and population compartment pharmacokinetic analysis.

Conclusion

The proposed method is simple to use and gives valuable information concerning time- and concentration-dependent inaccuracies that might occur in individual and population pharmacokinetic compartment analysis. Predictive performance can be quantified by the fraction of concentration ratios within arbitrarily specified ranges, e.g. within the range 0.8–1.2.

Caudal ropivacaine-clonidine: A better post-operative analgesic approach

The aim was to determine qualitative and quantitative aspects of caudal block, haemodynamic effects, and post-operative pain relief of ropivacaine 0.25% versus ropivacaine 0.25% with clonidine for lower abdominal surgeries in paediatric patients. A double-blind study was conducted among 44 paediatric patients in the Department of Anaesthesiology and Intensive Care of our institute. A total of 44 ASA-I paediatric patients between the ages of 1 and 9 years, scheduled for elective hernia surgery, were enrolled in this randomised double-blind study. The caudal block was administered with ropivacaine 0.25% (Group I) and ropivacaine 0.25% and clonidine 2 µg/kg (Group II) after induction with general anaesthesia. Haemodynamic parameters were observed before, during and after the surgical procedure. Post-operative analgesic duration, total dose of rescue analgesia, pain scores and any side effects were looked for and recorded. All the results were tabulated and analysed statistically. The variables in the two groups were compared using the non-parametric tests. For all statistical analyses, the level of significance was P < 0.05. Forty-four patients were enrolled in this study and their data were subjected to statistical analysis: 22 patients in both the groups were comparable with regard to demographic data, haemodynamic parameters and other vitals and were statistically non-significant (P>0.05). The duration of analgesia was significantly prolonged in Group II (P<0.05). The dose requirement for post-operative pain relief was also significantly lesser in Group II. The incidences of side effects were almost comparable and non-significant. A caudal block with 0.25% of isobaric ropivacaine combined with 2 µg/kg of clonidine provides efficient analgesia intra-operatively and prolonged duration of analgesia post-operatively.

Oral bioavailability of clonidine in children

BACKGROUND

Oral clonidine is used as premedication in children. The bioavailability of clonidine given orally in adults is 75-100% but is unknown in children.

METHODS

Children (3-10 years) undergoing adenotonsillectomy were administered oral clonidine 4 mcg·kg(-1) mixed with apple fruit drink as premedication. Intravenous plasma was assayed for clonidine concentration at 5, 15, 30, 45 min and 1, 2, 4, 6, 12, 18 h after administration. Clonidine plasma concentrations were determined by liquid chromatography-mass spectroscopy, and pharmacokinetic parameters were calculated using nonlinear effects mixed-effects models. Current data were pooled with published time-concentration profiles from children (n = 49) administered intravenous clonidine to determine oral bioavailability.

RESULTS

There were eight children studied (age 3-10 years, weight 10.5-36 kg). A two-compartment model with first-order absorption and elimination was used to describe time-concentration profiles. Population parameter estimates (CV%; 95% CI), standardized to a 70-kg person, were absorption half-life (Tabs), 0.45 (85.1; 0.221-0.884) h, absorption lag time (Tlag), 0.148 (91.2; 0.002-0.316) h, Clearance (CL) 17.9 (30.3; 16-20.3) l·h(-1) per 70 kg, between compartment clearance (Q) 121 (44.3; 80.1-165) l·h(-1) per 70 kg, central volume (V1) 81.2 (71.5; 60.7-105) l·70 kg(-1), peripheral volume of distribution (V2) 113 (33.9; 91-131) l·70 kg(-1). The oral bioavailability was 55.4% (CV 6.4%; 95% CI 0.469, 0.654).

CONCLUSIONS

Clonidine administered with an apple fruit drink displays a variable and relatively slow absorption after oral administration (T(max) 1.04 h, C(max) 0.77 mcg·l(-1)). The oral bioavailability was 55.4%, which is less than reported in adults. Consequently, higher oral doses of clonidine (per kg) are required when this formulation is used to achieve concentrations similar to those reported in adults.

Clonidine clearance matures rapidly during the early postnatal period: a population pharmacokinetic analysis in newborns with neonatal abstinence syndrome

The population pharmacokinetic (PK) profile of oral clonidine was characterized in newborns with neonatal abstinence syndrome, and significant covariates affecting its PK parameters were identified. Plasma clonidine concentration data were obtained from a clinical trial in which 36 newborns, aged 1 to 25 days (postnatal age, PNA) and weighing 2.1 to 3.9 kg, were enrolled to take multiple oral doses of clonidine. The population PK model of clonidine was developed by NONMEM, and significant covariates were identified, followed by nonparametric bootstraps (2000 replicates) and simulation experiments. A 1-compartment open linear PK model was chosen to describe plasma concentrations of clonidine, and body weight and PNA were significant covariates for apparent clearance (CL/F) as follows: CL/F (L/h) = 15.2 × [body weight (kg)/70](0.75) × [PNA (day)(0.441)/(4.06(0.441) + PNA (day)(0.441))]. Furthermore, CL/F of clonidine increased rapidly with PNA during the first month of life after body weight was adjusted. Any optimal dosage regimen for clonidine in term neonates should be based on infant's age and body weight, and 1.5 µg/kg every 4 hours is proposed starting the second week of life based on the simulation results.

Absorption pharmacokinetics of clonidine nasal drops in children

BACKGROUND

The alpha2 agonist clonidine has become a popular drug for premedication in children. Effects and pharmacokinetics after oral, rectal, and intravenous administration are well known. The aim of this study was to investigate the absorption pharmacokinetics of clonidine nasal drops in children.

METHODS

Thirteen ASA I pediatric patients received after induction of anesthesia 4 mcg x kg(-1) of clonidine by the nasal route. Blood samples were taken during a 12-h period and plasma levels of clonidine were analyzed by liquid chromatography-mass spectrometry. Data were calculated by a computer-aided curve-fitting program.

RESULTS

Plasma pharmacokinetics following administration of clonidine nasal drops showed a considerable interindividual variability and absorption was delayed and limited. A total of 95% confidence intervals for maximum plasma concentration and time to achieve maximum plasma concentration were 0.4-0.6 ng x ml(-1) and 1.4-3.0 h, respectively.

CONCLUSIONS

Clonidine nasal drops are erratically absorbed from the nasal mucosa and, thus, this mode of drug administration is not recommended for premedication purposes.

Clonidine disposition in children; a population analysis

BACKGROUND

There are few data describing clonidine population pharmacokinetics in children (0-15 years) despite common use. Current pediatric data, described in terms of elimination half-life or C(max) and T(max), poorly explain variability in drug responses among individuals representative of those in whom the drug will be used clinically.

METHODS

Published data from four studies investigating clonidine PK after intravenous (i.v.), rectal and epidural administration (n = 42) were combined with an open-label study undertaken to examine the pharmacokinetics of i.v. clonidine 1-2 microg x kg(-1) bolus in children after cardiac surgery (n = 41). A population pharmacokinetic analysis of clonidine time-concentration profiles (380 observations) was undertaken using nonlinear mixed effects modeling. Estimates were standardized to a 70-kg adult using allometric size models.

RESULTS

Children had a mean age of 4 (sd 3.6 years, range 1 week-14 years) years and weight 17.8 (sd 12.6, range 2.8-60) kg. A two compartment disposition model with first-order elimination was superior to a one compartment model. Population parameter estimates (between subject variability) were clearance (CL) 14.6 (CV 35.1%) l x h(-1 )70 kg(-1), central volume of distribution (V1) 62.5 (71.1%) l 70 kg(-1), intercompartment clearance (Q) 157 (77.3%) l x h(-1) 70 kg(-1) and peripheral volume of distribution (V2) 119 (22.9%) l 70 kg(-1). Clearance at birth was 3.8 l x h(-1) 70 kg(-1) and matured with a half-time of 25.7 weeks to reach 82% adult rate by 1 year of age. The volumes of distribution, but not clearance, were increased after cardiac surgery (V1 123%, V2 126%). There was a lag time of 2.3 (CV 73.2%) min before absorption began in the rectum. The absorption half-life from the epidural space was slower than that from the rectum (0.98 CV 24.5% h vs 0.26 CV 32.3% h). The relative bioavailability of epidural and rectal clonidine was unity (F = 1).

CONCLUSIONS

Clearance in neonates is approximately one-third that described in adults, consistent with immature elimination pathways. Maintenance dosing, which is a function of clearance, should be reduced in neonates and infants when using a target concentration approach.

Sensitive and convenient method for the quantification of clonidine in serum of pediatric patients using liquid chromatography/tandem mass spectrometry

An improved and easy to use liquid chromatography/tandem mass spectrometric (LC/MS/MS) method in human serum was developed for the quantification of clonidine (CLD), an alpha2-/alpha1-adrenoceptor agonist, used for analgo-sedation and the therapy of opioid withdrawal in pediatric patients. Sample preparation consisted of precipitation of serum proteins by adding acetonitrile and centrifugation of the sample subsequently. [(2)H4]Clonidine (CLD4) served as internal standard. Chromatographic separation of the supernatant was achieved using a 100mmx3mm, 5microm Thermo Electron BetaBasic C4 column with isocratic flow and elution consisting of 0.1% formic acid/acetonitrile (85/15, v/v) and a flow-rate of 350microl/min resulting in a column pressure of 280-420kPa. LC/MS/MS detection was performed by using a triple-stage quadrupole mass spectrometer (TSQ Quantum, Thermo Electron) working in selected reaction monitoring mode with positive electrospray ionization. The analyte was quantified in a single run within 5min. Linearity was demonstrated over the expected concentration range 0.15-50microg/l CLD. The lower limit of quantification (LLOQ) and the limit of detection were 0.1microg/l and 0.01microg/l, respectively. None of the drugs used concomitantly during analgesic therapy interfered in the assay in vitro. Intra-day precision expressed as RSD was 9.6% or less for CLD, while inter-day result was 10.0% or less for CLD. Intra-day and inter-day accuracy was within +/-4.9% and +/-1.8%, respectively. The method was validated according to the international guidelines of the International Conference on Harmonisation (ICH) and the US Food and Drugs Administration (FDA). The described method is suitable to analyse serum samples with very small volumes and sets the stage for pharmacokinetic studies in pediatric studies.

Recent developments in the pharmacological management of pain in children

PURPOSE OF REVIEW

This review explores progress in developmental pharmacokinetics, pharmacogenomics and formulations of analgesic agents, and discusses potential implications for pain therapy.

RECENT FINDINGS

Characterization of the developmental pharmacokinetics of morphine, tramadol, paracetamol and nonsteroidal anti-inflammatory drugs has improved dosing in children. Oral sugar solutions have replaced the brandy/sugar pacifier and are effective for single painful events in neonates. Intravenous paracetamol offers increased dosing accuracy, and avoids absorption and bioavailability variability. New nitric-oxide-releasing versions of paracetamol and nonsteroidal anti-inflammatory drugs offer safer alternatives to their parent drugs with enhanced potency. Ketamine has come under a cloud for its possible effects on the neonatal developing brain, but it is being used increasingly in children to supplement opioids for pain after major surgery. Hopes that morphine analgesia may improve neurological outcome in premature babies have not materialized. Reports concerning chronic pain are generally case series and controlled trials are rare and nearly nonexistent in children.

SUMMARY

Unlicensed drug use in the very young will increase as familiarity increases. Pharmacogenomic studies have the potential to tailor drug therapy to the individual and decrease between-patient variability. Unfortunately, the pharmacodynamic knowledge in children of analgesic agents remains neglected and is usually extrapolated from adult data.

Clonidine in paediatric anaesthesia: review of the literature and comparison with benzodiazepines for premedication

BACKGROUND

Children undergoing anaesthesia and surgery can experience significant anxiety and distress during the peri-operative period, but whether routine premedication is necessary is currently debated. Benzodiazepines are the most frequently used drugs as premedication in paediatric anaesthesia. In the US, 50% of young children undergoing surgery receive premedication and midazolam is the most frequently used drug in this context (1). Nishina and coworkers (2) concluded in a review article in 1999 that clonidine, administered via an oral, rectal, or caudal route, is a promising adjunct to anaesthetics and analgesics to enhance quality of peri-operative management in infants and children. Later publications also support the use of clonidine for premedication (3-6). The aim of this communication is to review the use of clonidine in paediatric anaesthesia and to propose clonidine as a promising alternative to midazolam. Clonidine is associated with a number of beneficial effects in the context ofanaesthesia both in adults and children. Why clonidine is not routinely use in clinical practice despite the massive publication list is to a large extent due to the lack of marketing efforts from the pharmaceutical industry since multiplegeneric preparations are now readily available on most markets. Midazolam is also associated with a number of beneficial effects, but is far from an ideal premedicant in children, especially with regards to the amnesia, confusion and long term behavioural disturbances. Clonidine has contrary to midazolam no effect on respiration. We believe that clonidine is a good alternative to midazolam as premedication in infants and children.

Assessment of Clonidine Orally Disintegrating Tablet for Pre-anesthetic Medication in Pediatric Surgery

The purpose of this study is to assess orally-disintegrating (OD) tablet of clonidine hydrochloride (CL) for a pre-operative sedation in pediatric surgery. Sedation score and plasma CL concentration of OD formulation was compared with original preparation, CL lollipop, in pediatric patients. Fourteen patients (age: 3.9+/-2.3 years, weight: 16.9+/-5.0 kg) for OD group and 9 patients (age: 4.4+/-3.1 years, weight: 17.2+/-7.0 kg) for lollipop group received 4 microg/kg of CL preparation. Pre-operative sedation was evaluated by 5-point scoring systems at entering the operating room. Plasma CL concentrations were determined 120 min after administration of CL preparation. The changes in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were also assessed before and after administration of CL preparation. Every patient in OD group had satisfactory sedation (sedation score: 2 and 3), whereas, 3 (33%) in lollipop group had unsatisfactory sedation (sedation score: 0 and 1). Plasma CL concentration in OD group was significantly higher than those in lollipop group (0.75+/-0.15 vs. 0.42+/-0.21 ng/ml, p<0.01). There was no significant difference in hemodynamic parameters (SBP, DBP and HR) between before and after administration of CL preparation in both OD and lollipop group. We conclude that OD is superior preparation of CL for pre-operative sedation in pediatric surgery.

Clonidine administered as adjuvant for bupivacaine in ilioinguinal-iliohypogastric nerve block does not prolong postoperative analgesia

BACKGROUND

Coadministration of clonidine with local anesthetics is associated with improvement of the quality of peripheral nerve block and significant prolongation of postoperative analgesia. Better analgesia has been reported with clonidine in ilioinguinal nerve block compared with caudal use. The object of this study was to determine whether adding of 1 microg.kg(-1) clonidine to bupivacaine 0.25% in ilioinguinal-iliohypogastric nerve block prolongs postoperative analgesia in children.

METHODS

Ninety-eight children ASA I-II aged between 1 and 12 years, scheduled for elective outpatient herniorrhaphy or orchidopexy were randomly allocated to receive an ilioinguinal-iliohypogastric nerve block either with 0.3 ml.kg(-1) bupivacaine 0.25% plus 1 microg.kg(-1) clonidine or only bupivacaine. Postoperative analgesic needs, time to the first analgesic supplementation and sedation score were assessed in hospital for 6 h postoperatively and at home by telephone call.

RESULTS

Demographic data were similar in both groups. There was no statistical difference in the rate of rescue analgesia between the two groups during the first six postoperative hours (20.4% group clonidine vs 30.6% group no clonidine) (P = 0.17). A slight decrease in systolic blood pressure during surgery was reported in the clonidine group. There was no difference in the scores of sedation between the two groups. At home, 10 patients in the clonidine group and nine patients in the nonclonidine group received analgesic medication. There was no difference between the two groups regarding the number of patients receiving analgesic rescue during the first 24 h (log rank = 0.39). Parental satisfaction was high in both groups.

CONCLUSIONS

Our study failed to demonstrate any advantage in addition of 1 microg.kg(-1) clonidine to 0.25% bupivacaine for ilioinguinal-iliohypogastric nerve block compared with bupivacaine 0.25% alone.

Use of oral clonidine for sedation in ventilated paediatric intensive care patients

OBJECTIVES

We aimed to document our experience with oral clonidine when used as a sedative in combination with intravenous morphine and lorazepam in a group of mechanically ventilated children with single-organ, respiratory failure. In particular, our objectives were to establish the relationship between oral dose, plasma concentration, and sedative effect, and second, to document the side-effect profile.

DESIGN

Prospective, cohort study over a 72-h period.

SETTING

Regional paediatric intensive care unit.

PATIENTS AND PARTICIPANTS

Twenty-four children were enrolled (median age 3 months) of whom ten were excluded (six due to extubation before 72 h, three sedation failures, one protocol violation).

MEASUREMENTS AND RESULTS

Plasma clonidine was measured using gas chromatography mass spectrometry, and sedation assessed using the COMFORT score. Using a dose of 3-5 microg/kg every 8 h, plasma concentrations appeared to plateau at approximately 41 h giving a mean value of 1.38 ng/ml (95% confidence interval 1.0-1.8). Adequate sedation was achieved during 82% (837/1022 h) of the study period; however, this decreased to 70.3% when analysed on an intention-to-treat basis. There was a concomitant overall decrease in the average hourly requirements for both morphine ( P = 0.02) and lorazepam ( P = 0.003). There were no documented episodes of bradycardia, hypotension or hyperglycaemia.

CONCLUSIONS

Oral clonidine may be a safe and effective sedative in combination with morphine and lorazepam for young children with single-organ, respiratory failure. This agent may also exhibit opioid and benzodiazepine sparing effects in this patient group. A full pharmacokinetic study is warranted.

Epidural infusion of clonidine or clonidine plus ropivacaine for postoperative analgesia in children undergoing major abdominal surgery

STUDY OBJECTIVE

To investigate the analgesic efficacy and safety of epidural infusion of clonidine in children undergoing major abdominal surgery.

DESIGN

Randomized open-label study.

SETTING

Postoperative anesthetic unit and pediatric ward of a metropolitan hospital.

PATIENTS

Forty children aged 0 to 3 years undergoing major abdominal surgery.

INTERVENTIONS

Children were randomly allocated to receive a 24-hour epidural infusion of clonidine 1 microg.mL(-1) at rate of 0.2 mL.kg -1.h -1 preceded by a bolus of 2 microg.kg -1 (CLON group) or a mixture of clonidine 1 microg.mL -1 and ropivacaine 0.1% at rate of 0.2 mL.kg -1.h -1. Both groups received intravenous (IV) ketoprofen 2 mg.kg -1 every 8 hours. Breakthrough pain was treated with IV tramadol 1 mg.kg(-1).

MEASUREMENTS

Tramadol requirement, sedation and respiratory and hemodynamic changes were measured.

MAIN RESULTS

Approximately 77% and 59.3% of the CLON and CLON+ROPIV groups, respectively, required no tramadol or only one dose over a 24-hour period. Except for those patients who exhibited frequent coughing during the night (4 and 5 patients in the CLON and CLON+ROPIV groups, respectively), no study patients required an analgesic and all had good sleep quality during the first night. Sedation and decreased systolic blood pressure were observed after the clonidine bolus was given.

CONCLUSION

For children undergoing major abdominal surgery, the addition of epidural infusion of clonidine or clonidine plus ropivacaine to IV ketoprofen provided good analgesia quality for postoperative rest pain.

Nonopioid additives to local anaesthetics for caudal blockade in children: a systematic review

BACKGROUND

Caudal epidural injection with local anaesthetics is a popular regional technique used in infants and children. A disadvantage of caudal blockade is the relatively short duration of postoperative analgesia. Opioids have traditionally been added to increase the duration of analgesia but have been associated with unacceptable side-effects. A number of nonopioid additives have been suggested to increase the duration of analgesia.

METHODS

A systematic review was conducted to identify randomized control trials comparing the use of local anaesthetic to local anaesthetic with nonopioid additives for caudal blockade in children. The increase in duration of analgesia and side-effects were compared.

RESULTS

The addition of clonidine to the local anaesthetic solution produces an increase in the duration of analgesia following caudal blockade in children (pooled weighted mean difference of 145 min with 95% confidence interval of 132-157 min). Side-effects include sedation and the potential for neonatal respiratory depression. Ketamine and midazolam further increase the duration of analgesia, however, the potential for neurotoxicity remains a concern.

CONCLUSION

The evidence examined shows an increased duration of analgesia with clonidine, ketamine and midazolam. However, we are not convinced that the routine use of these adjuvants in the setting of elective outpatient surgery shows improved patient outcome. It is unclear if the potential for neurotoxicity is outweighed by clinical benefits. Further testing, including large clinical trials, is required before recommending routine use of nonopioid additives for caudal blockade in children.

Side-effects of postoperative epidural analgesia in children: a randomized study comparing morphine and clonidine

BACKGROUND

Morphine is widely used in association with local anaesthetics for postoperative epidural analgesia. There are no data on the prolonged use of clonidine for postoperative analgesia in children. The primary outcome of this randomized, double-blind trial was to compare the incidence of side-effects after epidural infusion of clonidine or morphine, in association with ropivacaine in children.

METHODS

After institutional approval, 26 children, aged 3-12 years, who were scheduled for abdominal surgery, had an epidural catheter placed after induction of general anaesthesia. Patients were then randomized to two different groups. After an initial bolus of 2.5 mg x kg-1 0.25% ropivacaine with either 40 micro g x kg-1 morphine (group M, n = 14) or 1 micro g x kg-1 clonidine (group C, n = 12), an epidural infusion was started at a rate of 0.4 ml x kg-1 x h-1. The patients in the M group received an infusion of 0.08% ropivacaine with 10 micro g.ml-1 morphine, those in the group C an infusion of 0.08% ropivacaine with 0.6 micro g.ml-1 clonidine.

RESULTS

The two groups were similar with respect to age, sex and weight. One patient in the C group was excluded for misplacement of the epidural catheter. The incidence of vomiting and pruritus was significantly higher in the M group compared with the C group (64% and 85% versus 0%, respectively). The incidence of pain was significantly higher in the C group compared with the M group (73% versus 29%) as well as the need for rescue analgesia medications.

CONCLUSIONS

Epidural clonidine is followed by a significantly lower incidence of side-effects. However, its analgesic effects, at least at the doses used in this study, are less potent than those of epidural morphine.

Sedation and plasma concentration of clonidine hydrochloride for pre-anesthetic medication in pediatric surgery

Clonidine hydrochloride has been used for pre-anesthetic medication to provide a pre-operative sedation in pediatric surgery. The purpose of this study is to determine the plasma clonidine concentration, which gives satisfactory sedation in pediatric surgery. Sixteen pediatric patients (age: 1-11 years, weight: 9-33 kg) received either 2 or 4 microg/kg of clonidine lollipop before entering the operating room. Plasma clonidine concentrations were determined 120 min after administration of clonidine lollipop. Pre-operative sedation was evaluated by 5-point scoring systems at entering the operating room. The changes in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were also assessed before and after administration of clonidine lollipop. The patients with satisfactory sedation had higher plasma clonidine concentration than that of the patients with unsatisfactory sedation (0.45+/-0.16 ng/ml vs. 0.26+/-0.16 ng/ml, p<0.05). The clonidine concentrations in the satisfactory group ranged from 0.28 to 0.81 ng/ml. There was no significant difference in hemodynamic parameters (SBP, DBP and HR) before and after administration of clonidine lollipop in both satisfactory and unsatisfactory sedation groups. Plasma clonidine concentration of 0.3-0.8 ng/ml would be sufficient to produce satisfactory sedation without changes in hemodynamic parameters in pediatric surgery.

Spinal versus peripheral effects of adjunct clonidine: comparison of the analgesic effect of a ropivacaine-clonidine mixture when administered as a caudal or ilioinguinal-iliohypogastric nerve blockade for inguinal surgery in children

BACKGROUND

The adjunctive use of clonidine to local anaesthetics has been reported to enhance analgesia both after spinal and peripheral administration. However, no attempt has been made to compare spinal and peripheral application of clonidine in the same surgical context in order to further explore the mechanism for the analgesic action of clonidine when administered together with local anaesthetics.

METHODS

Using a prospective, randomized, observer-blinded study design, 40 patients, aged 1-7 years, who were undergoing elective surgery for inguinal hernia repair or orchidopexy, were randomly allocated to receive either a caudal block (group C: n = 20; ropivacaine 0.2%, 1 ml.kg-1 + clonidine 2 micro g.kg-1) or an ilioinguinal-iliohypogastric nerve block (group I: n = 20; ropivacaine 0.2%, 0.4 ml.kg-1 + clonidine 2 micro g.kg-1) following the induction of a standardized sevoflurane based anaesthetic. Postoperative analgesia [maximum Objective Pain Scale (OPS) score and requirement for supplemental analgesia] and sedation (three-point scale) were assessed at predetermined intervals during the first 24 h postoperatively.

RESULTS

Fourteen children in group I and nine children in group C did not require rescue analgesia (P = 0.17). No difference in maximum OPS scores could be detected between the two study groups. The mean time to full recovery regarding sedation was 149 min and 153 min in groups C and I, respectively.

CONCLUSIONS

This pilot study demonstrates a trend for better postoperative analgesia following peripheral administration of clonidine compared with central application. However, the main mechanism for the adjunct analgesic effect of clonidine when administered together with local anaesthetics requires further study.

New concepts in acute and extended postoperative pain management in children

Increased knowledge of the pathophysiology of pain in children and an improved understanding of the pharmacology and pharmacodynamics of multiple agents have provided the clinician with a wide variety of tools to treat postoperative pain in children. The interest in a multimodal approach is kindled by the realization that the combination of a number of therapies can enhance analgesia with fewer untoward side effects. The expertise of other health care professionals should be tapped to open new avenues of treatment. Many therapies still require critical evidence-based evaluations to assess how well they work in larger patient populations. Dedication to research, compassionate patient care, and a willingness to teach the next generation of clinicians will bring us closer to the goal of safe and pain-free surgery.

Pediatric thoracic anesthesia

The anesthesiologist caring for infants and children undergoing thoracic surgery faces many challenges. An understanding of the primary underlying lesion as well as associated anomalies that may impact perioperative management is paramount. A working knowledge of respiratory physiology and anatomy in infants and children is required for the planning and execution of appropriate intraoperative care. Familiarity with a variety of techniques for SLV suited to the patient's size will allow maximal surgical exposure while minimizing trauma to the lungs and airways. Finally, use of regional anesthetic techniques, including epidural anesthesia and analgesia, facilitates optimal postoperative pain control and pulmonary function.

How to prolong postoperative analgesia after caudal anaesthesia with ropivacaine in children: S-ketamine versus clonidine

BACKGROUND

The aim of the study was to determine whether caudal S-ketamine or clonidine prolonged analgesia together with ropivacaine.

METHODS

Sixty-three boys, aged 1-5 years, who were undergoing minor surgery, were allocated in order to receive one of three solutions for caudal anaesthesia. Group R received 2 mg x kg(-1) 0.2% ropivacaine; group C, 2 mg x kg(-1) 0.2% ropivacaine + clonidine 2 microg x kg(-1); and group K, 2 mg x kg(-1) 0.2% ropivacaine + S-ketamine 0.5 mg x kg(-1).

RESULTS

Postoperative analgesia assessed by CHEOPS lasted 701 min in group K (P < 0.05) compared with 492 min in group C and 291 min in group R. There were no significant differences between the groups for incidence of haemodynamic and respiratory alterations, motor block or sedation.

CONCLUSIONS

This study demonstrates that S-ketamine 0.5 mg x kg(-1) when added to 0.2% caudal ropivacaine provides better postoperative analgesia than clonidine without any clinically significant side-effect.

The dose-response relationship for clonidine added to a postoperative continuous epidural infusion of ropivacaine in children

Epidurally administered clonidine enhances the quality and duration of postoperative analgesia when it is used as an adjunct to local anesthetics in children. We investigated the dose-response relationship for epidural clonidine when added to a continuous postoperative epidural infusion of ropivacaine. By use of an observer-blinded design, 55 pediatric patients (1-4 yr old) were randomly given a postoperative epidural infusion of plain ropivacaine 0.1% 0.2 mg. kg(-1). h(-1) (Group R), ropivacaine 0.08% 0.16 mg. kg(-1). h(-1) plus clonidine 0.04 microg. kg(-1). h(-1) (Group RC1), ropivacaine 0.08% 0.16 mg. kg(-1). h(-1) plus clonidine 0.08 microg. kg(-1). h(-1) (Group RC2), or ropivacaine 0.08% 0.16 mg. kg(-1). h(-1) plus clonidine 0.12 microg. kg(-1). h(-1) (Group RC3). A clear dose-response relationship could be identified for a continuous infusion of epidural clonidine, with clonidine dosages in the 0.08-0.12 microg. kg(-1). h(-1) range providing improved postoperative analgesia (reduced Children's Hospital of Eastern Ontario pain score, increased time to first supplemental analgesic demand, and a reduced total number of doses of supplemental analgesics during the first 48 h after surgery). Analgesia was improved without any signs of increased sedation or other side effects. The adjunct use of epidural clonidine in the dosage range of 0.08-0.12 microg. kg(-1). h(-1) appears effective and safe for use in children.

IMPLICATIONS

The addition of clonidine (0.08-0.12 microg.kg(-1).h(-1))to a continuous epidural infusion of ropivacaine was found to improve postoperative pain relief in children. No clinically significant signs of sedation or other side effects were observed.

New insights into paediatric regional anaesthesia: new drugs

Over the years paediatric regional anaesthesia has gained a worldwide consensus, and it can now be considered a significant part of perioperative pain control in children. As in many fields, with the use of drugs administered epidurally there is a fundamental need for safety and efficacy. Two new local anaesthetic agents have recently entered the market, ropivacaine and levobupivacaine, which seem to offer a wider safety margin in comparison with the old drugs as well as valid pain control. To prolong their analgesic duration, many adjuvants can be used, and clonidine and ketamine are probably the best solution. This review summarizes the most recent data on these drugs and their use in children.

Ropivacaine-clonidine combination for caudal blockade in children

BACKGROUND

Adding clonidine to weak ropivacaine solutions (<0.2%) could potentially enhance analgesia as well as further reduce the risk for unwanted motor blockade. The aim of the present study was to compare the postoperative pain-relieving quality of a ropivacaine 0.1%-clonidine mixture to that of plain ropivacaine 0.2% following caudal administration in children.

METHODS

In a prospective, observer-blinded fashion, 40 ASA 1 paediatric patients undergoing subumbilical surgery were randomly allocated to receive a caudal injection of either plain ropivacaine 0.2% (1 ml/kg) (R0.2) or a mixture of ropivacaine 0.1% with clonidine 2 microg/kg (1 ml/kg) (R0.1C). Objective pain scale score and need for supplemental analgesia were used to evaluate analgesia during the first 24 h postoperatively. Residual postoperative sedation was also assessed.

RESULTS

A significantly higher number of patients in the R0.1C group (18/20) could be managed without supplemental analgesia during the first 24 h postoperatively compared to the R0.2 group (11/20) (P=0.034). Both the degree and the duration of postoperative sedation was similar in both groups. No signs of postoperative motor blockade were observed.

CONCLUSIONS

The combination of clonidine (2 microg/kg) and ropivacaine 0.1% is associated with an improved quality of postoperative analgesia compared to plain 0.2% ropivacaine. The improved analgesic quality of the clonidine-ropivacaine mixture is achieved without causing any significant degree of postoperative sedation.