An aid to drug dosing safety in obese children: development of a new nomogram and comparison with existing methods for estimation of ideal body weight and lean body mass

Tofacitinib pharmacokinetics in children and adolescents with juvenile idiopathic arthritis

These analyses characterized tofacitinib pharmacokinetics (PKs) in children and adolescents with juvenile idiopathic arthritis (JIA). Data were pooled from phase I (NCT01513902), phase III (NCT02592434), and open-label, long-term extension (NCT01500551) studies of tofacitinib tablet/solution (weight-based doses administered twice daily [b.i.d.]) in patients with JIA aged 2 to less than 18 years. Population PK modeling used a nonlinear mixed-effects approach, with covariates identified using stepwise forward-inclusion backward-deletion procedures. Simulations were performed to derive dosing recommendations for children and adolescents with JIA. Two hundred forty-six pediatric patients were included in the population PK model. A one-compartment model with first-order elimination and absorption with body weight as a covariate for oral clearance and apparent volume of distribution sufficiently described the data. Oral solution was associated with comparable average concentration (Cavg) and slightly higher (113.9%) maximum concentration (Cmax) versus tablet, which was confirmed by a subsequent randomized, open-label, bioavailability study conducted in healthy adult participants (n = 12) by demonstrating adjusted geometric mean ratios (90% confidence interval) between oral solution and tablet of 1.04 (1.00-1.09) and 1.10 (1.00-1.21) for area under the curve extrapolated to infinity and Cmax, respectively (NCT04111614). A dosing regimen of 3.2 mg b.i.d. solution in patients 10 to less than 20 kg, 4 mg b.i.d. solution in patients 20 to less than 40 kg, and 5 mg b.i.d. tablet/solution in patients greater than or equal to 40 kg, irrespective of age, was proposed to achieve constant Cavg across weight groups. In summary, population PK characterization informed a simplified tofacitinib dosing regimen that has been implemented in pediatric patients with JIA.

Plateau Pressure and Driving Pressure in Volume- and Pressure-Controlled Ventilation: Comparison of Frictional and Viscoelastic Resistive Components in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To examine frictional, viscoelastic, and elastic resistive components, as well threshold pressures, during volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) in pediatric patients with acute respiratory distress syndrome (ARDS).

DESIGN

Prospective cohort study.

SETTING

Seven-bed PICU, Hospital El Carmen de Maipú, Chile.

PATIENTS

Eighteen mechanically ventilated patients less than or equal to 15 years old undergoing neuromuscular blockade as part of management for ARDS.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients were in VCV mode during measurement of pulmonary mechanics, including: the first pressure drop (P1) upon reaching zero flow during the inspiratory hold, peak inspiratory pressure (PIP), plateau pressure (P PLAT ), and total positive end-expiratory pressure (tPEEP). We calculated the components of the working pressure, as defined by the following: frictional resistive = PIP-P1; viscoelastic resistive = P1-P PLAT ; purely elastic = driving pressure (ΔP) = P PLAT -tPEEP; and threshold = intrinsic PEEP. The procedures and calculations were repeated on PCV, keeping the same tidal volume and inspiratory time. Measurements in VCV were considered the gold standard. We performed Spearman correlation and Bland-Altman analysis. The median (interquartile range [IQR]) for patient age was 5 months (2-17 mo). Tidal volume was 5.7 mL/kg (5.3-6.1 mL/kg), PIP cm H 2 O 26 (23-27 cm H 2 O), P1 23 cm H 2 O (21-26 cm H 2 O), P PLAT 19 cm H 2 O (17-22 cm H 2 O), tPEEP 9 cm H 2 O (8-9 cm H 2 O), and ΔP 11 cm H 2 O (9-13 cm H 2 O) in VCV mode at baseline. There was a robust correlation (rho > 0.8) and agreement between frictional resistive, elastic, and threshold components of working pressure in both modes but not for the viscoelastic resistive component. The purely frictional resistive component was negligible. Median peak inspiratory flow with decelerating-flow was 21 (IQR, 15-26) and squared-shaped flow was 7 L/min (IQR, 6-10 L/min) ( p < 0.001).

CONCLUSIONS

P PLAT , ΔP, and tPEEP can guide clinical decisions independent of the ventilatory mode. The modest purely frictional resistive component emphasizes the relevance of maintaining the same safety limits, regardless of the selected ventilatory mode. Therefore, peak inspiratory flow should be studied as a mechanism of ventilator-induced lung injury in pediatric ARDS.

The effect of percentage of ideal body weight on outcomes in ileo-anal pull through for ulcerative colitis

PURPOSE

Ileo-anal pull through (IAPT) is a commonly performed operation for the surgical management of ulcerative colitis. The effect of body weight on outcomes for patients undergoing this operation has not been extensively studied.

METHODS

This was a prospective cohort study at a single tertiary care inflammatory bowel disease (IBD) center. A total of 457 patients who were operated on at the Mount Sinai Medical Center between 1983 and 2015 were included. Demographic characteristics, the patients' body weight at the time of IAPT, and postoperative outcome data were collected.

RESULTS

For each patient, body weight was calculated as a percentage of the ideal body weight (IBW) for that patient's height. The mean percentage of ideal body weight was 93.9% with a standard deviation of 20%. The range for the population was 53.1 to 175%. Four hundred forty (96%) of the patients had a weight within two standard deviations of the mean, indicating a normal distribution. Seventy-nine patients developed a Clavien-Dindo class III complication necessitating a procedural treatment. The most common of these was a stricture at the anastomotic site (n = 54). Our study identified an association between a percentage of ideal body weight in the lowest quartile of our population and development of an anastomotic stricture. This association was statistically significant on multivariate analysis.

CONCLUSION

Low body weight at the time of ileo-anal pull through for treatment of UC may be a risk factor for development of anastomotic stricture requiring dilation.

Evaluation of age-banded dosing of oral paracetamol in hospitalised children: a retrospective analysis using clinical data in a tertiary paediatric hospital

OBJECTIVE

To evaluate age-banded dosing in paediatric inpatients by determining the proportion of patients whose dose would fall outside the therapeutic range (by weight).

DESIGN

A retrospective observational study. Weight and height measurements and details of hospital admissions were matched from the electronic patient record of a single, tertiary paediatric hospital. Dosage which would be given according to age-banded dosing was then compared with their weight.

PARTICIPANTS

All children admitted to a single tertiary children's hospital aged 3 months to 16 years over a 5-year period. Data were cleaned to remove values likely to be erroneous and filtered to reduce bias due to patients who were admitted on multiple occasions.

OUTCOMES

The main outcome was the proportion of patients who would receive a subtherapeutic or supratherapeutic paracetamol dose if given a dose based on their age. Secondary outcomes were to examine this in children of different ages and to examine the impact of alternative size-based dosing strategies.

RESULTS

100 047 admissions (in 68 310 patients) had a weight documented. If age-banded dosing had been used, a subtherapeutic dose (less than 10 mg/kg) would be given during 19 829 (20%) of the admissions and a supratherapeutic dose (over 18.75 mg/kg, 75 mg/kg/day in four doses) in 4289 (4.3%). The highest risk of a subtherapeutic dose occurred in infants just prior to reaching 6 months of age (83%) and in children just prior to reaching 8 years (66%). The highest risk of a supratherapeutic dose was at 12 years of age (35%).

CONCLUSION

Age-banded dosing is not suitable for an inpatient paediatric population as approximately a quarter of patients receive a dose outside the recommended range of 10.0-18.75 mg/kg.

Comparison of growth response and adverse reaction according to growth hormone dosing strategy for children with short stature: LG Growth Study

OBJECTIVE

Growth hormone (GH) dosage in children is conventionally determined either by body weight (BW) or body surface area (BSA). However, there is no consensus on the calculation method for proper GH treatment dose. We aimed to compare growth response and adverse reactions between BW- and BSA-based GH treatment doses for children with short statures.

DESIGN

Data from 2284 GH-treated children were analyzed. Distributions of BW- and BSA-based GH treatment doses and their association with growth response parameters, including changes in height, height standard deviation score (SDS), body mass index (BMI), and safety parameters, such as changes in insulin-like growth factor (IGF)-I SDS and adverse events, were investigated.

RESULTS

The mean BW-based doses were close to the recommended dose's upper limit in participants with GH deficiency and idiopathic short stature, while they were below the recommended dose in patients with Turner syndrome (TS). As age and BW increased, BW-based dose decreased, whereas BSA-based dose increased. Gain in height SDS was positively associated with BW-based dose in the TS group and negatively associated with BW in all groups. Despite having a lower BW-based dose, the overweight/obese groups had a higher BSA-based dose and higher frequencies of children with high IGF-I and adverse events than those of the normal-BMI group.

CONCLUSIONS

In children of older age or with high BW, BW-based doses can be overdosed in terms of BSA. and BW-based dose positively correlated with height gain only in the TS group. BSA-based doses represent an alternative dosing strategy in children who are overweight/obese.

Dosing Variation at Initiation of Adalimumab and Etanercept and Clinical Outcomes in Juvenile Idiopathic Arthritis: A Childhood Arthritis and Rheumatology Research Alliance Registry Study

OBJECTIVE

To determine the dose-response relationship of tumor necrosis factor (TNF) inhibition in the treatment of juvenile idiopathic arthritis (JIA).

METHODS

Participants of the Childhood Arthritis and Rheumatology Research Alliance Registry were eligible for inclusion in the analyses if they started TNF inhibition treatment for JIA. The primary treatment response was determined 3 to 7 months after the start of treatment, based on the JIA American College of Rheumatology Pediatric criteria for improvement, clinical Juvenile Arthritis Disease Activity Score, and persistence of treatment after 6 months. Subsequently, pooled logistic regression models were performed to include long-term follow-up data. The models were adjusted for risk factors associated with poor treatment response. Dosing was expressed by body weight, body surface area, ideal body weight, fat free mass, and lean body mass.

RESULTS

Participants treated with adalimumab (n = 328) and etanercept (n = 437) were included in the analyses (median dose 0.82 mg/kg body weight [interquartile range (IQR) 0.66-1.04] and 0.83 mg/kg body weight [IQR 0.75-0.95], respectively). The majority of analyses did not show a relationship between dose and outcome. Where associations were found, results were conflicting. Alternative dosing characteristics based on ideal body weight, fat free mass, and lean body mass did not result in stronger or more consistent associations.

CONCLUSION

This study was not able to confirm our hypothesis that increased dosing of TNF inhibitors results in improved treatment outcomes. Although adjustment was performed for risk factors of impaired treatment response, residual confounding by indication likely explains the negative associations found in this study.

Characterizing Pharmacokinetics in Children With Obesity-Physiological, Drug, Patient, and Methodological Considerations

Childhood obesity is an alarming public health problem. The pediatric obesity rate has quadrupled in the past 30 years, and currently nearly 20% of United States children and 9% of children worldwide are classified as obese. Drug distribution and elimination processes, which determine drug exposure (and thus dosing), can vary significantly between patients with and without obesity. Obesity-related physiological changes, such as increased tissue volume and perfusion, altered blood protein concentrations, and tissue composition can greatly affect a drug's volume of distribution, which might necessitate adjustment in loading doses. Obesity-related changes in the drug eliminating organs, such as altered enzyme activity in the liver and glomerular filtration rate, can affect the rate of drug elimination, which may warrant an adjustment in the maintenance dosing rate. Although weight-based dosing (i.e., in mg/kg) is commonly practiced in pediatrics, choice of the right body size metric (e.g., total body weight, lean body weight, body surface area, etc.) for dosing children with obesity still remains a question. To address this gap, the interplay between obesity-related physiological changes (e.g., altered organ size, composition, and function), and drug-specific properties (e.g., lipophilicity and elimination pathway) needs to be characterized in a quantitative framework. Additionally, methodological considerations, such as adequate sample size and optimal sampling scheme, should also be considered to ensure accurate and precise top-down covariate selection, particularly when designing opportunistic studies in pediatric drug development. Further factors affecting dosing, including existing dosing recommendations, target therapeutic ranges, dose capping, and formulations constraints, are also important to consider when undergoing dose selection for children with obesity. Opportunities to bridge the dosing knowledge gap in children with obesity include modeling and simulating techniques (i.e., population pharmacokinetic and physiologically-based pharmacokinetic [PBPK] modeling), opportunistic clinical data, and real world data. In this review, key considerations related to physiology, drug parameters, patient factors, and methodology that need to be accounted for while studying the influence of obesity on pharmacokinetics in children are highlighted and discussed. Future studies will need to leverage these modeling opportunities to better describe drug exposure in children with obesity as the childhood obesity epidemic continues.

Opioids for acute pain management in children

Opioids are integral to multimodal analgesic regimens in children with moderate to severe acute pain. Throughout normal childhood there are marked changes in physiology, and social and psychological development that influence the perception and expression of pain, the pharmacology of opioids, and how they are used. A multidimensional pain assessment is key to guiding appropriate opioid prescribing. Most of the commonly used opioids in adults are used in children, with the increasing exception of codeine (as a result of regulatory change), and are generally well tolerated. Patient groups at increased risk of ventilatory impairment include neonates and those with obstructive sleep apnoea, severe neurodevelopmental conditions, trisomy 21, and severe epilepsy. Slow-release opioids are not recommended for general use, but may be used in select populations, for example, following scoliosis surgery, major trauma or burns. Prescribing and administration errors are a major issue in paediatrics generally; the potential consequences of opioid prescribing or administration errors are serious, particularly following hospital discharge. Opioids prescribed at discharge are frequently in excess of a child's analgesic requirements; three to five days supply appears sufficient for the majority of common paediatric operations. Discharge opioid prescriptions have been linked to long-term opioid use in adolescents with risk factors. Misuse of prescription opioids by adolescents is also concerning, with prevalence estimates ranging from 1.1% to 20%. Caregivers have a tendency to underdose opioids in their children; caregiver education may improve appropriate administration. Caregivers must also be provided with instructions on safe storage and disposal of unused opioids.

A Retrospective Review of Opioid Prescribing Practices for At-Risk Pediatric Populations Undergoing Ambulatory Surgery

OBJECTIVE

Pediatric patients with sleep-disordered breathing (SDB) and obesity are at risk for opioid-induced respiratory depression. Although monitoring in the inpatient setting allows for early recognition of opioid-related adverse events, there is far less vigilance after ambulatory surgery as patients are discharged home. Guidelines for proper opioid dosing in these pediatric subsets have not been established. We sought to determine if at-risk children were more likely to receive doses of opioids outside the recommended range.

METHODS

Baseline opioid prescribing data for all outpatient surgery patients receiving an opioid prescription between January 2019 and June 2020 were retrospectively reviewed. Patients with SDB or obesity were identified. To obtain more information about prescribing practices, we analyzed patient demographics, size descriptors used for calculations, and prescription characteristics (dose, duration, and prescribing surgical service).

RESULTS

A total of 4674 patients received an opioid prescription after outpatient surgery. Of those, 173 patients had SDB and 128 were obese. Surgical subspecialties rendering most of the opioid prescriptions included otolaryngology and orthopedics. Obese patients were more likely (64%) to be prescribed opioids using ideal weight at higher mg/kg doses (>0.05 mg/kg; 83.3%; p < 0.0001). When providers used actual body weight, lower mg/kg doses were more likely to be used (53.7%; p < 0.0001). No prescriptions used lean body mass.

CONCLUSIONS

Overweight/obese children were more likely to receive opioid doses outside the recommended range. Variability in prescribing patterns demonstrates the need for more detailed guidelines to minimize the risk of opioid-induced respiratory complications in vulnerable pediatric populations.

Driving Pressure and Normalized Energy Transmission Calculations in Mechanically Ventilated Children Without Lung Disease and Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

To compare the new tools to evaluate the energy dissipated to the lung parenchyma in mechanically ventilated children with and without lung injury. We compared their discrimination capability between both groups when indexed by ideal body weight and driving pressure.

DESIGN

Post hoc analysis of individual patient data from two previously published studies describing pulmonary mechanics.

SETTING

Two academic hospitals in Latin-America.

PATIENTS

Mechanically ventilated patients younger than 15 years old were included. We analyzed two groups, 30 children under general anesthesia (ANESTH group) and 38 children with pediatric acute respiratory distress syndrome.

INTERVENTIONS

Respiratory mechanics were measured after intubation in all patients.

MEASUREMENTS AND MAIN RESULTS

Mechanical power and derived variables of the equation of motion (dynamic power, driving power, and mechanical energy) were computed and then indexed by ideal body weight. Driving pressure was higher in pediatric acute respiratory distress syndrome group compared with ANESTH group. Receiver operator curve analysis showed that driving pressure had the best discrimination capability compared with all derived variables of the equation of motion indexed by ideal body weight. The same results were observed when the subgroup of patients weighs less than 15 kg. There was no difference in unindexed mechanical power between groups.

CONCLUSIONS

Driving pressure is the variable that better discriminates pediatric acute respiratory distress syndrome from nonpediatric acute respiratory distress syndrome in children than the calculations derived from the equation of motion, even when indexed by ideal body weight. Unindexed mechanical power was useless to differentiate against both groups. Future studies should determine the threshold for variables of the energy dissipated by the lungs and their association with clinical outcomes.

The utility of pediatric age-based weight estimation formulas for emergency drug dose calculations in obese children

OBJECTIVES

In obese children, when drug therapy is required during emergency care, an estimation of ideal body weight is required for certain drug dose calculations. Some experts have previously speculated that age-based weight estimation formulas could be used to predict ideal body weight. The objectives of this study were to evaluate how accurately age-based formulas could predict ideal body weight and total body weight in obese children.

METHODS

Three age-based weight estimation formulas were evaluated in a secondary analysis, using a pooled sample of children from 3 academic emergency departments in South Africa. The estimates produced by the 3 formulas (and the PAWPER XL tape as a control) were compared against measured total body weight and ideal body weight. The percentages of estimates falling within 10% of the standard weight were used as the primary outcome measure (PW10).

RESULTS

This study included 1026 children. For ideal body weight estimations in obese children, the old Advanced Life Support formula, the new Advanced Life Support formula, and the Best Guess formula achieved PW10s (with 95% confidence intervals [CIs]) of 29% (27.2%, 30.8%), 41.4% (38.9%, 43.9%), and 48.3% (45.3%, 51.3%), respectively. For total body weight estimations, the formulas achieved PW10s of 3.6% (3.4%, 3.8%), 5.2% (4.9%, 5.5%), and 19.0% (17.8%, 20.2%). The PAWPER XL tape achieved an accuracy of ideal body weight estimation of 100% (93.9%, 100%) and total body weight estimation of 49.7% (46.7%, 52.7%) in obese children.

CONCLUSIONS

The age-based formulas were substantially less accurate at estimating total body weight and ideal body weight than existing length-based methods such as the PAWPER XL tape, and should not be used for this purpose.

Medication Dosing Safety for Pediatric Patients: Recognizing Gaps, Safety Threats, and Best Practices in the Emergency Medical Services Setting. A Position Statement and Resource Document from NAEMSP

BACKGROUND

Millions of patients receive medications in the Emergency Medical Services (EMS) setting annually, and dosing safety is critically important. The need for weight-based dosing in pediatric patients and variability in medication concentrations available in the EMS setting may require EMS providers to perform complex calculations to derive the appropriate dose to deliver. These factors can significantly increase the risk for harm when dose calculations are inaccurate or incorrect.

METHODS

We conducted a scoping review of the EMS, interfacility transport and emergency medicine literature regarding pediatric medication dosing safety. A priori, the authors identified four research topics: (1) what are the greatest safety threats that result in significant dosing errors that potentially result in harm to patients, (2) what practices or technologies are known to enhance dosing safety, (3) can data from other settings be extrapolated to the EMS environment to inform dosing safety, and (4) what impact could standardization of medication formularies have on enhancing dosing safety. To address these topics, 17 PICO (Patient, Intervention, Comparison, Outcome) questions were developed and a literature search was performed.

RESULTS

After applying exclusion criteria, 70 articles were reviewed. The methods for the investigation, findings from these articles and how they inform EMS medication dosing safety are summarized here. This review yielded 11 recommendations to improve safety of medication delivery in the EMS setting.

CONCLUSION

These recommendations are summarized in the National Association of EMS Physicians® position statement: Medication Dosing Safety for Pediatric Patients in Emergency Medical Services.

Practicalities of Total Intravenous Anesthesia and Target-controlled Infusion in Children

Propofol administered in conjunction with an opioid such as remifentanil is used to provide total intravenous anesthesia for children. Drugs can be given as infusion controlled manually by the physician or as automated target-controlled infusion that targets plasma or effect site. Smart pumps programmed with pharmacokinetic parameter estimates administer drugs to a preset plasma concentration. A linking rate constant parameter (keo) allows estimation of effect site concentration. There are two parameter sets, named after the first author describing them, that are commonly used in pediatric target-controlled infusion for propofol (Absalom and Kataria) and one for remifentanil (Minto). Propofol validation studies suggest that these parameter estimates are satisfactory for the majority of children. Recommended target concentrations for both propofol and remifentanil depend on the type of surgery, the degree of surgical stimulation, the use of local anesthetic blocks, and the ventilatory status of the patient. The use of processed electroencephalographic monitoring is helpful in pediatric total intravenous anesthesia and target-controlled infusion anesthesia, particularly in the presence of neuromuscular blockade.

The Society for Pediatric Anesthesia recommendations for the use of opioids in children during the perioperative period

Opioids have long held a prominent role in the management of perioperative pain in adults and children. Published reports concerning the appropriate, and inappropriate, use of these medications in pediatric patients have appeared in various publications over the last 50 years. For this document, the Society for Pediatric Anesthesia appointed a taskforce to evaluate the available literature and formulate recommendations with respect to the most salient aspects of perioperative opioid administration in children. The recommendations are graded based on the strength of the available evidence, with consensus of the experts applied for those issues where evidence is not available. The goal of the recommendations was to address the most important issues concerning opioid administration to children after surgery, including appropriate assessment of pain, monitoring of patients on opioid therapy, opioid dosing considerations, side effects of opioid treatment, strategies for opioid delivery, and assessment of analgesic efficacy. Regular updates are planned with a re-release of guidelines every 2 years.

Association Between Tidal Volumes Adjusted for Ideal Body Weight and Outcomes in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

The impact of tidal volume on outcomes in mechanically ventilated children with pediatric acute respiratory distress syndrome remains unclear. To date, observational investigations have failed to calculate tidal volume based on standardized corrections of weight. We investigated the impact of tidal volume on mortality and probability of extubation in pediatric acute respiratory distress syndrome using ideal body weight-adjusted tidal volume.

DESIGN

Retrospective analysis of an ongoing prospective cohort of pediatric acute respiratory distress syndrome patients. Tidal volume was calculated based on actual body weight and two different formulations of ideal body weight.

SETTING

PICU at a large, tertiary care children's hospital.

PATIENTS

Pediatric acute respiratory distress syndrome patients on conventional ventilation with a documented height or length.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 483 patients with a measured height or length at pediatric acute respiratory distress syndrome onset included in the final analysis, with 73 nonsurvivors (15%). At 24 hours, there remained 400 patients on conventional ventilation. When calculating tidal volume based on ideal body weight by either method, volumes were larger both at onset and at 24 hours compared with tidal volume based on actual body weight (all p < 0.001), and the proportion of patients being ventilated with tidal volumes greater than 10 mL/kg based on ideal body weight was larger both at onset (12.4% and 15.5%) and 24 hours (10.3% and 11.5%) compared with actual body weight at onset (3.5%) and 24 hours (4.0%) (all p < 0.001). Tidal volume, based on both actual body weight and ideal body weight, was not associated with either increased mortality or decreased probability of extubation after adjusting for oxygenation index in the whole cohort, whereas associations between higher tidal volume and poor outcomes were seen in subgroup analyses in overweight children and in severe pediatric acute respiratory distress syndrome.

CONCLUSIONS

Our retrospective analysis of a cohort of pediatric acute respiratory distress syndrome patients did not find a consistent association between tidal volume adjusted for ideal body weight and outcomes, although an association may exist in certain subgroups. Although it remains to be shown in a prospective trial whether high volumes or pressures are injurious in pediatric acute respiratory distress syndrome, tidal volume is likely an imprecise parameter for titrating lung-protective ventilation.

Perioperative considerations for airway management and drug dosing in obese children

PURPOSE OF REVIEW

Childhood obesity, a phenomenon that is increasing globally, holds substantial relevance for pediatric anesthesia. In particular, understanding the nuances of airway management and drug dosing in obese children can be daunting.

RECENT FINDINGS

Respiratory adverse events and challenges in managing the airway may be anticipated. In addition, drug-dosing strategies for the obese child are complex and poorly understood although recent advances have clarified the optimal dosing for anesthetics in these children.

SUMMARY

Theoretical knowledge, practical skills, meticulous risk stratification and optimal drug regimens are crucial to ensure the safe conduct of anesthesia for obese children.

Peri-operative management of overweight and obese children and adolescents

Obesity has become endemic, even in children. Systemic complications associated with obesity include metabolic syndrome, cardiovascular disease, and respiratory compromise. These comorbidities require adequate investigation, targeted optimisation, and, if surgery is required, specific management during the peri-operative period. Specific peri-operative strategies should be used for paediatric patients who are overweight or obese to prevent postoperative complications, and optimising the respiratory function during surgery is particularly crucial. This Review aims to provide up-to-date information on peri-operative management for physicians who are caring for children and adolescents (usually younger than 18 years) who are overweight or obese undergoing surgery, including bariatric surgery. We have particularly focussed on the physiological consequences of obesity-namely, obstructive sleep apnoea, respiratory compromise, and pharmacological considerations.

What is the best size predictor for dose in the obese child?

Lean body mass is commonly proposed for anesthesia maintenance drug dosing calculations. However, total body mass used with allometric scaling has been shown to be better for propofol in obese adults and children. Fat-free mass has also been used instead of lean body mass. Fat-free mass is essentially the same as lean body mass but excludes a small percentage of mass of lipids in cell membranes, CNS, and bone marrow. Normal fat mass is a size descriptor that partitions total body mass into fat-free mass and fat mass calculated from total body mass minus fat-free mass. The relative influence of fat mass compared with fat-free mass is described by the fraction of fat mass that makes fat equivalent to fat-free mass in terms of allometric size. This fraction (Ffat) will differ for each drug and each parameter affected by body size (eg, clearance and volume of distribution). This fraction is based on the concept of theory-based allometric size. The normal fat mass based on allometric theory and partition of body mass into fat and fat-free components provides a principle-based approach explaining size and body composition effects on pharmacokinetics of all drugs in children and in adults.

Growth hormone prescribing and initial BMI SDS: Increased biochemical adverse effects and costs in obese children without additional gain in height

Background

Recombinant human growth hormone (rhGH) treatment in children is usually prescribed using actual body weight. This may result in inappropriately high doses in obese children.

Methods

Retrospective audit of all paediatric patients treated with rhGH 2010–14 at a tertiary paediatric hospital in the UK. Change in height SDS and IGF-I SDS during the first year of treatment was stratified by initial BMI SDS in a mixed cohort, and a subgroup of GH deficient (GHD) patients. Alternative doses for those BMI SDS ≥2.0 (Obese) were calculated using BSA, IBW and LBW.

Results

354 patients (133 female) received rhGH, including 213 (60.2%) with GHD. Obesity was present in 40 patients (11.3%) of the unselected cohort, and 32 (15.0%) of the GHD cohort. For GHD patients, gain in height SDS was directly related to BMI SDS, except in obese patients (p<0.05). For both the entire cohort, and GHD patients only, IGF-1 SDS was significantly higher in obese patients (p<0.0001 for both groups). Cross sectional data identified 265 children receiving rhGH, 81 (30.5%) with a BMI-SDS ≥1.75. Alternate prescribing strategies for rhGH prescribing in obese patients suggest a saving of 27% - 38% annually.

Conclusions

Gain in IGF-I SDS is greater in obese children, and is likely to be related to relatively higher doses of rhGH. Additional gain in height was not achieved at the higher doses administered to obese children. Alternative dosing strategies in the obese patient population should be examined in rigorous clinical trials.

The accuracy of timed maximum local anaesthetic dose calculations with an electronic calculator, nomogram, and pen and paper

Forty anaesthetists calculated maximum permissible doses of eight local anaesthetic formulations for simulated patients three times with three methods: an electronic calculator; nomogram; and pen and paper. Correct dose calculations with the nomogram (85/120) were more frequent than with the calculator (71/120) or pen and paper (57/120), Bayes Factor 4 and 287, p = 0.01 and p = 0.0003, respectively. The rates of calculations at least 120% the recommended dose with each method were different, Bayes Factor 7.9, p = 0.0007: 14/120 with the calculator; 5/120 with the nomogram; 13/120 with pen and paper. The median (IQR [range]) speed of calculation with pen and paper, 38.0 (25.0-56.3 [5-142]) s, was slower than with the calculator, 24.5 (17.8-37.5 [6-204]) s, p = 0.0001, or nomogram, 23.0 (18.0-29.0 [4-100]) s, p = 1 × 10^-7 . Local anaesthetic dose calculations with the nomogram were more accurate than with an electronic calculator or pen and paper and were faster than with pen and paper.

Medication Dosage in Overweight and Obese Children

Approximately 31.8% of U.S. children ages 2 to 19 years are considered overweight or obese. This creates significant challenges to dosing medications that are primarily weight based (mg/kg) and in predicting pharmacokinetics parameters in pediatric patients. Obese individuals generally have a larger volume of distribution for lipophilic medications. Conversely, the Vd of hydrophilic medications may be increased or decreased due to increased lean body mass, blood volume, and decrease percentage of total body water. They may also experience decreased hepatic clearance secondary to fatty infiltrates of the liver. Hence, obesity may affect loading dose, dosage interval, plasma half-life, and time to reach steady-state concentration for various medications. Weight-based dosing is also a cause for potential medication errors. This position statement of the Pediatric Pharmacy Advocacy Group recommends that weight-based dosing should be used in patients ages < 18 years who are < 40 kg; weight-based dosing should be used in patients ≥ 40 kg, unless, unless the recommended adult dose for the specific indication is exceeded; clinicians should use pharmacokinetic analysis for adjusting medications in overweight/obese children; and research efforts continue to evaluate dosing of medications in obese/overweight children.

Assessment of inpatient admissions and top 25 medications for obese pediatric patients at two academic hospitals

PURPOSE

Inpatient admissions and the top 25 medications for obese pediatric patients at two academic hospitals were assessed.

METHODS

Children age 2-17 years were included if they were obese and admitted to either hospital on or after January 1, 2011, and discharged before December 31, 2011. Obesity was defined as a body mass index of ≥95th percentile for age and sex. The objectives of this study were to determine the percentage of hospital admissions involving obese children and compile a list of medications prescribed to these patients. The top 25 medications prescribed were further evaluated to determine their pharmacokinetic disposition in obese patients.

RESULTS

Obese children accounted for 18.8% of the 15,119 admissions for children age 2-17 years at the two study hospitals. No significant difference was noted in the number of obese pediatric children admitted between institutions. A total of 28,234 medications were ordered for this population, with a median number of 8 medications prescribed per admission. Sixteen of the same medications (64.0%) ranked in the top 25 at each facility. The most commonly prescribed medications for these patients included analgesics, antimicrobials, corticosteroids, bronchodilators, and gastrointestinal agents.

CONCLUSION

Obese children accounted for 18.8% of admissions for patients age 2-17 years at two academic hospitals over a 1-year period. The most commonly prescribed medications for these children included analgesics, antimicrobials, corticosteroids, bronchodilators, and gastrointestinal agents. The literature guiding the dosing of these medications in this population was limited to seven studies, representing just three medications.

Perioperative support reduces mortality of obese BALB/c mice after ovariectomy

The incidence of obesity is on the rise in most western countries and represents major risks to health. Obesity causes complex metabolic dysfunctions and can be associated with a large number of secondary diseases. To investigate causal mechanisms of obesity and develop better options for treatment, researchers study the condition in animal models. In addition to genetically engineered animal models, diet-induced obesity is often used because it occurs similarly in animals as it does in humans. For several types of investigations that use obesity models, investigators must carry out surgical interventions and they frequently encounter severe perioperative complications induced by anesthesia. In an example of this problem, we observed 100% mortality in obese BALB/c mice after ovariectomy, despite no obvious surgical complications. We supposed that a failure to recover from surgery was the primary cause of this increased mortality. Therefore, to support their recovery from surgery we administered atropine to obese mice in order to facilitate blood circulation, and we also increased the oxygen content of the ambient air. With this specific support before and after surgery, we increased the survival rate of obese ovariectomized mice up to 83%. These results confirm the assumption that obesity is a risk factor for the recovery of obese animal models after ovariectomy, and they highlight the need to provide additional interventions for such experimental animals.

Pediatric dental sedation: challenges and opportunities

High levels of dental caries, challenging child behavior, and parent expectations support a need for sedation in pediatric dentistry. This paper reviews modern developments in pediatric sedation with a focus on implementing techniques to enhance success and patient safety. In recent years, sedation for dental procedures has been implicated in a disproportionate number of cases that resulted in death or permanent neurologic damage. The youngest children and those with more complicated medical backgrounds appear to be at greatest risk. To reduce complications, practitioners and regulatory bodies have supported a renewed focus on health care quality and safety. Implementation of high fidelity simulation training and improvements in patient monitoring, including end-tidal carbon dioxide, are becoming recognized as a new standard for sedated patients in dental offices and health care facilities. Safe and appropriate case selection and appropriate dosing for overweight children is also paramount. Oral sedation has been the mainstay of pediatric dental sedation; however, today practitioners are administering modern drugs in new ways with high levels of success. Employing contemporary transmucosal administration devices increases patient acceptance and sedation predictability. While recently there have been many positive developments in sedation technology, it is now thought that medications used in sedation and anesthesia may have adverse effects on the developing brain. The evidence for this is not definitive, but we suggest that practitioners recognize this developing area and counsel patients accordingly. Finally, there is a clear trend of increased use of ambulatory anesthesia services for pediatric dentistry. Today, parents and practitioners have become accustomed to children receiving general anesthesia in the outpatient setting. As a result of these changes, it is possible that dental providers will abandon the practice of personally administering large amounts of sedation to patients, and focus instead on careful case selection for lighter in-office sedation techniques.