Anesthetizing the obese child

Preoperative preparation and postoperative care in children in thoracic surgery

Anesthesia for pediatric patients undergoing thoracic surgery continues to be distinctive due to differing anatomical and physiological characteristics compared to adults. Adequate preoperative preparation, appropriate tool selection for providing one-lung ventilation, perioperative pain management, and a multidisciplinary approach can ensure higher quality postoperative care. In this review, the perioperative anesthesia management for pediatric patients undergoing thoracic surgery will be discussed, starting from the preoperative preparation phase. Additionally, the issues related to the application and management of one-lung ventilation will also be assessed.

Childhood Obesity: An Updated Review

BACKGROUND

Childhood obesity is an important and serious public health problem worldwide.

OBJECTIVE

This article aims to familiarize physicians with the evaluation, management, and prevention of childhood.

METHODS

A PubMed search was conducted in May, 2021, in Clinical Queries using the key terms "obesity" OR "obese". The search included clinical trials, randomized controlled trials, case-control studies, cohort studies, meta-analyses, observational studies, clinical guidelines, case reports, case series, and reviews. The search was restricted to English literature and children. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Most obese children have exogenous obesity characterized by a growth rate for height above the 50th percentile, normal intelligence, normal genitalia, and lack of historical or physical evidence of an endocrine abnormality or a congenital syndrome. Obese children are at risk for dyslipidemia, hypertension, diabetes mellitus, non-alcoholic fatty liver disease, obstructive sleep apnea, psychosocial disturbances, impaired quality of life, and shorter life expectancy. The multitude of serious comorbidities necessitates effective treatment modalities. Dietary modification, therapeutic exercise, and behavioral modification are the fundamentals of treatment. Pharmacotherapy and/or bariatric surgery should be considered for obese individuals who do not respond to the above measures and suffer from a serious comorbid condition.

CONCLUSION

Childhood obesity, once established, is often refractory to treatment. Most treatment programs lead to a brief period of weight loss, followed by rapid re-accumulation of the lost weight after the termination of therapy. As such, preventive activity is the key to solving the problem of childhood obesity. Childhood obesity can be prevented by promoting a healthy diet, regular physical activity, and lifestyle modification. Parents should be encouraged to get involved in school and community programs that improve their children's nutritional status and physical activity.

Perioperative Acetaminophen Dosing in Obese Children

Acetaminophen is a commonly used perioperative analgesic drug in children. The use of a preoperative loading dose achieves a target concentration of 10 mg/L associated with a target analgesic effect that is 2.6 pain units (visual analogue scale 1–10). Postoperative maintenance dosing is used to keep this effect at a steady-state concentration. The loading dose in children is commonly prescribed per kilogram. That dose is consistent with the linear relationship between the volume of distribution and total body weight. Total body weight is made up of both fat and fat-free mass. The fat mass has little influence on the volume of distribution of acetaminophen but fat mass should be considered for maintenance dosing that is determined by clearance. The relationship between the pharmacokinetic parameter, clearance, and size is not linear. A number of size metrics (e.g., fat-free and normal fat mass, ideal body weight and lean body weight) have been proposed to scale clearance and all consequent dosing schedules recognize curvilinear relationships between clearance and size. This relationship can be described using allometric theory. Fat mass also has an indirect influence on clearance that is independent of its effects due to increased body mass. Normal fat mass, used in conjunction with allometry, has proven a useful size metric for acetaminophen; it is calculated using fat-free mass and a fraction (Ffat) of the additional mass contributing to total body weight. However, the Ffat for acetaminophen is large (Ffat = 0.82), pharmacokinetic and pharmacodynamic parameter variability high, and the concentration–response slope gentle at the target concentration. Consequently, total body weight with allometry is acceptable for the calculation of maintenance dose. The dose of acetaminophen is tempered by concerns about adverse effects, notably hepatotoxicity associated with use after 2–3 days at doses greater than 90 mg/kg/day.

Considerations for Intravenous Anesthesia Dose in Obese Children: Understanding PKPD

The intravenous induction or loading dose in children is commonly prescribed per kilogram. That dose recognizes the linear relationship between volume of distribution and total body weight. Total body weight comprises both fat and fat-free mass. Fat mass influences the volume of distribution and the use of total body weight fails to recognize the impact of fat mass on pharmacokinetics in children. Size metrics alternative to total body mass (e.g., fat-free and normal fat mass, ideal body weight and lean body weight) have been proposed to scale pharmacokinetic parameters (clearance, volume of distribution) for size. Clearance is the key parameter used to calculate infusion rates or maintenance dosing at steady state. Dosing schedules recognize the curvilinear relationship, described using allometric theory, between clearance and size. Fat mass also has an indirect influence on clearance through both metabolic and renal function that is independent of its effects due to increased body mass. Fat-free mass, lean body mass and ideal body mass are not drug specific and fail to recognize the variable impact of fat mass contributing to body composition in children, both lean and obese. Normal fat mass, used in conjunction with allometry, may prove a useful size metric but computation by clinicians for the individual child is not facile. Dosing is further complicated by the need for multicompartment models to describe intravenous drug pharmacokinetics and the concentration effect relationship, both beneficial and adverse, is often poorly understood. Obesity is also associated with other morbidity that may also influence pharmacokinetics. Dose is best determined using pharmacokinetic-pharmacodynamic (PKPD) models that account for these varied factors. These models, along with covariates (age, weight, body composition), can be incorporated into programmable target-controlled infusion pumps. The use of target-controlled infusion pumps, assuming practitioners have a sound understanding of the PKPD within programs, provide the best available guide to intravenous dose in obese children.

Tonsillectomy for Obstructive Sleep-Disordered Breathing: Should They Stay, or Could They Go?

OBJECTIVES/HYPOTHESIS

Children who do not require oxygen beyond 3 hours after surgery and pass a sleep room air challenge (SRAC) are safe for discharge regardless of polysomnogram (PSG) results or comorbidities.

STUDY DESIGN

Cross-sectional prospective study.

METHODS

All children observed overnight undergoing an adenotonsillectomy for obstructive sleep-disordered breathing were prospectively recruited. Demographic, clinical, and PSG characteristics were stratified by whether the patient had required oxygen beyond 3 hours postoperatively (prolonged oxygen requirement [POR]) and compared using t test, chi-squared test, or Fisher's exact test depending on distribution. Optimal cut points for predicting POR postsurgery were calculated using receiver operating characteristic curves. The primary analysis was performed on the full cohort via logistic regression using POR as the outcome. Significant characteristics were analyzed in a logistic regression model, with significance set at P < .05.

RESULTS

A total of 484 participants met the inclusion criteria. The mean age was 5.65 (standard deviation = 4.02) years. Overall, 365 (75%) did not have a POR or any other adverse respiratory event. In multivariable logistic regression, risk factors for POR were an asthma diagnosis (P < .001) and an awake SpO2  <96% (P = .005). The probability of a POR for those without asthma and a SpO2  ≥ 96% was 18% (95% confidence interval: 14-22). Age, obesity, and obstructive apnea/hypopnea index were not associated with POR.

CONCLUSIONS

In conclusion, all children in our study who are off oxygen within 3 hours of surgery and passed a SRAC were safe for discharge from a respiratory standpoint regardless of age, obesity status, asthma diagnosis, and obstructive apnea/hypopnea index. Additional investigations are necessary to confirm our findings.

LEVEL OF EVIDENCE

3 Laryngoscope, 132:1675-1681, 2022.

Perioperative respiratory adverse events during ambulatory anesthesia in obese children

Obesity is one of the most common clinical conditions in the pediatric population with an increasing prevalence ranging from 20 to 30% worldwide. It is well known that during ambulatory anesthesia, obese children are more prone to develop perioperative respiratory adverse events (PRAEs) associated with obesity. To avoid or at least minimize these adverse effects, a thorough preoperative assessment should be undertaken as well as consideration of specific anesthetic approaches such as preoxygenation before induction of anesthesia and optimizing drug dosing. The use of short-acting opioid and nonopioid analgesics and the frequent implementation of regional anesthesia should also be included. Noninvasive airway management, protective mechanical ventilation, and complete reversion of neuromuscular blockade and awake extubation also proved to be beneficial in preventing PRAEs. During the postoperative period, continuous monitoring of oxygenation and ventilation is mandatory in obese children. In the current review, we sought to provide recommendations that might help to reduce the severity of perioperative respiratory adverse events in obese children, which could be of particular importance for reducing the rate of unplanned hospitalizations and ultimately improving the overall postoperative recovery.

Pharmacokinetic Pharmacodynamic Modelling Contributions to Improve Paediatric Anaesthesia Practice

The use of pharmacokinetic-pharmacodynamic models has improved anaesthesia practice in children through a better understanding of dose-concentration-response relationships, developmental pharmacokinetic changes, quantification of drug interactions and insights into how covariates (e.g., age, size, organ dysfunction, pharmacogenomics) impact drug prescription. Simulation using information from these models has enabled the prediction and learning of beneficial and adverse effects and decision-making around clinical scenarios. Covariate information, including the use of allometric size scaling, age and consideration of fat mass, has reduced population parameter variability. The target concentration approach has rationalised dose calculation. Paediatric pharmacokinetic-pharmacodynamic insights have led to better drug delivery systems for total intravenous anaesthesia and an expectation about drug offset when delivery is stopped. Understanding concentration-dependent adverse effects have tempered dose regimens. Quantification of drug interactions has improved the understanding of the effects of drug combinations. Repurposed drugs (e.g., antiviral drugs used for COVID-19) within the community can have important effects on drugs used in paediatric anaesthesia, and the use of simulation educates about these drug vagaries.

The physiologically difficult airway: an emerging concept

PURPOSE OF REVIEW

The physiologically difficult airway is one in which physiologic alterations in the patient increase the risk for cardiorespiratory and other complications during tracheal intubation and transition to positive pressure ventilation. This review will summarize the recent literature around the emerging concept of the physiologically difficult airway, describe its relevance and various patient types in which this entity is observed.

RECENT FINDINGS

Physiologic derangements during airway management occur due acute illness, pre-existing disease, effects of anesthetic agents, and positive pressure ventilation. These derangements are especially recognized in critically ill patients, but can also occur in otherwise healthy patients including obese, pregnant and pediatric patients who have certain physiological alterations. Critically ill patients may have a physiologically difficult airway due to the presence of acute respiratory failure, hypoxemia, hypotension, severe metabolic acidosis, right ventricular failure, intracranial hypertension, and risk of aspiration of gastric contents during tracheal intubation.

SUMMARY

Understanding the physiological alterations and the risks involved in patients with a physiologically difficult airway is necessary to optimize the physiology and adopt strategies to avoid complications during tracheal intubation. Further research will help us better understand the optimal strategies to improve outcomes in these patients.

Medication Errors in Overweight and Obese Pediatric Patients: A Narrative Review

BACKGROUND

The childhood obesity epidemic in the United States has increased utilization of health care and prescribing of medications in overweight and obese children, yet it is unclear whether this has led to more medication errors. The objective of this study was to review all available literature on incidence and types of medication errors in overweight and obese children.

METHODS

A search of MEDLINE, Embase, and Scopus databases was conducted for all studies and oral abstracts through December 2020 reporting medication errors in overweight or obese children aged ≤ 18 years. All studies were identified and extracted via a Covidence database. Two reviewers independently reviewed studies and rated the methodologic quality of those included per GRADE (Grading of Recommendations, Assessment, Development and Evaluations) criteria.

RESULTS

The search identified 1,016 abstracts from databases. Following review, full text was obtained for 146 articles, of which 141 were excluded. A total of 5 studies met criteria for inclusion and described dosing errors of antimicrobials, anesthetics, and paracetamol in overweight and obese pediatric patients. Two of the 5 studies compared medication errors in obese to nonobese children, and both found that medication errors (both over- and underdosing) were generally more common among obese children. The identified reasons for medication errors included incorrect dosing weight, incorrect dosing strategy, over- and underdosing with weight-based and flat-fixed dosing, and inapposite use of age-based dosing schemas.

CONCLUSION

There is a paucity of patient safety evidence available evaluating medication use in overweight and obese children and associated medication errors. Overweight and obese children may be at increased risk of medication errors, although the clinical significance of this is unknown.

Pharmacokinetic concepts for dexmedetomidine target-controlled infusion pumps in children

Pharmacokinetic parameter estimates are used in mathematical equations (pharmacokinetic models) to describe concentration changes with time in a population and are specific to that population. Simulation using these models and their parameter estimates can enrich understanding of drug behavior and serve as a basis for study design. Pharmacokinetic concepts are presented pertaining to future designs of dexmedetomidine target-controlled infusion pumps in children. This manuscript provides the pediatric anesthesiologist with an understanding of the nuances that should be considered when using target-controlled infusion pumps; how the central volume may differ between populations, how clearance changes with age, and the impact of adverse effects on dose. In addition, the ideal loading dose and rate of delivery to achieve target concentration without adverse cardiovascular effects are reviewed, and finally, dose considerations for obese children, based on contact-sensitive half-time, are introduced. An understanding of context-sensitive half-time changes with age enables anesthetic practitioners to better estimate duration of effect after cessation of dexmedetomidine infusion. Use of these known pharmacokinetic parameters and covariate information for the pediatric patient could readily be incorporated into commercial target-controlled infusion pumps to allow effective and safe open-loop administration of dexmedetomidine in children.

Recognizing Risks and Optimizing Perioperative Care to Reduce Respiratory Complications in the Pediatric Patient

There have been significant advancements in the safe delivery of anesthesia as well as improvements in surgical technique; however, the perioperative period can still be high risk for the pediatric patient. Perioperative respiratory complications (PRCs) are some of the most common critical events that can occur in pediatric surgical patients and they can lead to increased length of hospitalization, worsened patient outcomes, and higher hospital and postoperative costs. It is important to determine the various factors that put pediatric patients at increased risk of PRCs. This will allow for more detailed and accurate informed consent, optimized perioperative management strategy, improved allocation of clinical resources, and, hopefully, better patient experience. There are only a few risk prediction models/scoring tools developed for and validated in the pediatric patient population, but they have been useful in helping identify the key factors associated with a high likelihood of developing PRCs. Some of these factors are patient factors, while others are procedure-related factors. Some of these factors may be modified such that the patient’s clinical status is optimized preoperatively to decrease the risk of PRCs occurring perioperatively. Fore knowledge of the factors that are not able to be modified can help guide allocation of perioperative clinical resources such that the negative impact of these non-modifiable factors is buffered. Additional training in pediatric anesthesia or focused expertise in pediatric airway management, vascular access and management of massive hemorrhage should be considered for the perioperative management of the less than 3 age group. Intraoperative ventilation strategy plays a key role in determining respiratory outcomes for both adult and pediatric surgical patients. Key components of lung protective mechanical ventilation strategy such as low tidal volume and moderate PEEP used in the management of acute respiratory distress syndrome (ARDS) in pediatric intensive care units have been adopted in pediatric operating rooms. Adequate post-operative analgesia that balances pain control with appropriate mental status and respiratory drive is important in reducing PRCs.

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.

Pediatric Ambulatory Anesthesia Challenges

Ambulatory surgery in the pediatric population can be similar to adult ambulatory with a few different challenges. Success is best determined by appropriate preoperative screening. Issues common in pediatrics are the respiratory infection, asthma, congenital heart disease and syndromes, as well as sleep apnea. Risk factors for adverse respiratory events and patient transfer differ from adults as do data for rapid discharge.

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.

Advances in pharmacokinetic modeling: target controlled infusions in the obese

PURPOSE OF REVIEW

The use of conventional pharmacokinetic parameters sets 'models' derived from nonobese patients has proven inadequate to administer intravenous anesthetics in the obese population and is commonly associated with higher than anticipated plasma propofol concentrations when used with target (plasma or effect site) controlled infusion pumps. In this review we will describe recent modeling strategies to characterize the disposition of intravenous anesthetics in the obese patient and will show clinically relevant aspects of new model's performance in the obese population.

RECENT FINDINGS

Because clearance of a drug increases in a nonlinear manner with weight, nonlinear relationships better scale infusion rates between lean and obese individuals. Allometric concepts have been successfully used to describe size-related nonlinear changes in clearances. Other nonlinear scaling options include the use of descriptors such as body surface area, lean body weight, fat-free mass, and normal fat mass. Newer pharmacokinetic models, determined from obese patient data, have been developed for propofol and remifentanil using allometric concepts and comprehensive size descriptors.

SUMMARY

Pharmacokinetic models to perform target-controlled infusion in the obese population should incorporate descriptors that reflect with greater precision the influence of body composition in volumes and clearances of each drug. It is our hope that commercially available pumps will soon incorporate these new models to improve the performance of this technique in the obese population.

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.

Zika Virus: Obstetric and Pediatric Anesthesia Considerations

As of November 2016, the Florida Department of Health (FDH) and the Centers for Disease Control and Prevention have confirmed more than 4000 travel-related Zika virus (ZIKV) infections in the United States with >700 of those in Florida. There have been 139 cases of locally acquired infection, all occurring in Miami, Florida. Within the US territories (eg, Puerto Rico, US Virgin Islands), >30,000 cases of ZIKV infection have been reported. The projected number of individuals at risk for ZIKV infection in the Caribbean and Latin America approximates 5 million. Similar to Dengue and Chikungunya viruses, ZIKV is spread to humans by infected Aedes aegypti mosquitoes, through travel-associated local transmission, via sexual contact, and through blood transfusions. South Florida is an epicenter for ZIKV infection in the United States and the year-round warm climate along with an abundance of mosquito vectors that can harbor the flavivirus raise health care concerns. ZIKV infection is generally mild with clinical manifestations of fever, rash, conjunctivitis, and arthralgia. Of greatest concern, however, is growing evidence for the relationship between ZIKV infection of pregnant women and increased incidence of abnormal pregnancies and congenital abnormalities in the newborn, now medically termed ZIKA Congenital Syndrome. Federal health officials are observing 899 confirmed Zika-positive pregnancies and the FDH is currently monitoring 110 pregnant women with evidence of Zika infection. The University of Miami/Jackson Memorial Hospital is uniquely positioned just north of downtown Miami and within the vicinity of Liberty City, Little Haiti, and Miami Beach, which are currently "hot spots" for Zika virus exposure and transmissions. As the FDH works fervently to prevent a Zika epidemic in the region, health care providers at the University of Miami and Jackson Memorial Hospital prepare for the clinical spectrum of ZIKV effects as well as the safe perioperative care of the parturients and their affected newborns. In an effort to meet anesthetic preparedness for the care of potential Zika-positive patients and perinatal management of babies born with ZIKA Congenital Syndrome, this review highlights the interim guidelines from the Centers for Disease Control and Prevention and also suggest anesthetic implications and recommendations. In addition, this article reviews guidance for the evaluation and anesthetic management of infants with congenital ZIKV infection. To better manage the perioperative care of affected newborns, this article also reviews the comparative anesthetic implications of babies born with related congenital malformations.

Sleep and Breathing the First Night After Adenotonsillectomy in Obese Children With Obstructive Sleep Apnea

STUDY OBJECTIVES

There are few studies measuring postoperative respiratory complications in obese children with obstructive sleep apnea (OSA) undergoing adenotonsillectomy (AT). These complications are further compounded by perioperative medications. Our objective was to study obese children with OSA for their respiratory characteristics and sleep architecture on the night of AT.

METHODS

This was a prospective study at a tertiary pediatric hospital between January 2009-February 2012. Twenty obese children between 8-17 years of age with OSA and adenotonsillar hypertrophy were recruited. Patients underwent baseline polysomnography (PSG) and AT with or without additional debulking procedures, followed by a second PSG on the night of surgery. Demographic and clinical variables, surgical details, perioperative anesthetics and analgesics, and PSG respiratory and sleep architecture parameters were recorded. Statistical tests included Pearson correlation coefficient for correlation between continuous variables and chi-square and Wilcoxon rank-sum tests for differences between groups.

RESULTS

Baseline PSG showed OSA with mean obstructive apnea-hypopnea index (oAHI) 27.1 ± 22.9, SpO₂ nadir 80.1 ± 7.9%, and sleep fragmentation-arousal index 25.5 ± 22.0. Postoperatively, 85% of patients had abnormal sleep studies similar to baseline, with postoperative oAHI 27.0 ± 34.3 (P = .204), SpO₂ nadir, 82.0 ± 8.7% (P = .462), and arousal index, 24.3 ± 24.0 (P = .295). Sleep architecture was abnormal after surgery, showing a significant decrease in REM sleep (P = .003), and a corresponding increase in N2 (P = .017).

CONCLUSIONS

Obese children undergoing AT for OSA are at increased risk for residual OSA on the night of surgery. Special considerations should be taken for postoperative monitoring and treatment of these children.

COMMENTARY

A commentary on this article appears in this issue on page 775.

Desaturation in procedural sedation for children with long bone fractures: Does weight status matter?

INTRODUCTION

Childhood obesity remains a serious problem in the United States. Significant associated adverse incidents have been reported with sedation of children with obesity, namely hypoxemia. The objective of our study was to determine if overweight and obesity were associated with increased desaturations during procedural sedation compared with patients of healthy weight.

METHODS

This was a single-center retrospective chart review of data from a three-year period of patient's age 2-17years. Of the 1700 charts reviewed 823 of these patients received procedural sedation and met the study inclusion criteria. Weight status was classified based on age and gender specific body mass index (BMI) percentiles: underweight, healthy weight, overweight, obese.

RESULTS

Among all weight categories there was no statistical significance, however children with obesity had greater desaturation rates (9.9%) compared with children of underweight, healthy weight, or overweight combined (5.4%), χ²=4.46, p=0.035.

DISCUSSION

The results indicate that children with obesity are almost twice as likely to have a desaturation related to procedural sedation compared with children of other weight status. Providers should be aware that children with obesity may be more likely to desaturate than other children, and therefore be skilled at recognizing this.

A clinical trial evaluating the laryngeal mask airway-Supreme in obese children during general anesthesia

INTRODUCTION

The laryngeal mask airway (LMA)-Supreme is a disposable double-lumen laryngeal mask airway that is widely used in clinical practice. However, its use in obese children has not been evaluated. The aim of this study was to determine whether the LMA-Supreme could perform equally as well as endotracheal intubation in obese children having a minor surgical procedure.

MATERIAL AND METHODS

After ethical board approval, 100 obese male children receiving non-emergent appendectomy for chronic appendicitis or surgery to correct concealed penis were randomly divided into an endotracheal intubation group and an LMA-Supreme group. Endotracheal intubation was performed under direct vision laryngoscopy. In the LMA group, a size-3 LMA-Supreme was placed and a stomach tube inserted via the drainage tube of the mask. Cardiovascular and respiratory parameters, time taken for placement, placement attempts, time to removal of the endotracheal tube/LMA, length of stay in the post-anesthesia care unit (PACU), and complications were recorded.

RESULTS

Insertion time was significantly longer (p < 0.001) in the LMA-Supreme group than in the endotracheal intubation group. Peak airway pressure was significantly higher, and pulmonary compliance and PACU stay time lower in the LMA-Supreme group. No significant differences between endotracheal intubation and the LMA-Supreme were seen in other parameters, except for a higher incidence of coughing in the endotracheal intubation group.

CONCLUSIONS

The LMA-Supreme can be easily inserted and effectively used for airway management in obese children undergoing minor surgery.

Pediatric perioperative adverse events requiring rapid response: a retrospective case-control study

BACKGROUND

Perioperative pediatric adverse events have been challenging to study within and across institutions due to varying definitions, low event rates, and incomplete capture.

AIM

The aim of this study was to determine perioperative adverse event prevalence and to evaluate associated case characteristics and potential contributing factors at an academic pediatric quaternary-care center.

METHODS

At the Children's Hospital of Philadelphia (CHOP), perioperative adverse events requiring rapid response assistance are termed Anesthesia Now (AN!) events. They have been accurately captured and entered into a quality improvement database since 2010. Adverse events involving open heart and cardiac catheterization cases are managed separately and not included in this database. We conducted a retrospective case-control study utilizing Compurecord (Phillips Healthcare, Andover, MA, USA), EPIC (EPIC, Verona, WI, USA), and Chartmaxx (MedPlus, Mason, OH, USA) systems matching AN! event cases to noncardiac controls (1 : 2) based on surgical date.

RESULTS

From April 16, 2010 to September 25, 2012, we documented 213 AN! events in the noncardiac perioperative complex and remote sites at our main hospital. AN! prevalence was 0.0043 (1 : 234) with a 95% confidence interval (CI) (0.0037, 0.0049). Respiratory events, primarily laryngospasm, were most common followed by events of cardiovascular etiology. Median age was lower in the AN! group than in controls, 2.86 years (interquartile range 0.94, 10.1) vs 6.20 (2.85, 13.1), P < 0.0001. Odds ratios (with 95% CI) for age, 0.969 (0.941, 0.997); American Society of Anesthesiologists physical status, 1.67 (1.32, 2.12); multiple (≥2) services, 2.27 (1.13, 4.55); nonoperating room vs operating room location, 0.240 (0.133, 0.431); and attending anesthesiologist's experience, 0.976 (0.959, 0.992) were all significant.

CONCLUSIONS

Decreased age, increased comorbidities, multiple (vs single) surgical services, operating room (vs nonoperating room) location, and decreased staff experience were associated with increased risk of AN! events, which were predominantly respiratory in origin.

The impact of obesity on pediatric procedural sedation-related outcomes: results from the Pediatric Sedation Research Consortium

OBJECTIVES

To evaluate the impact of obesity on adverse events and required interventions during pediatric procedural sedation.

METHODS

The Pediatric Sedation Research Consortium database of prospectively collected procedural sedation encounters was queried to identify patients for whom body mass index (BMI) could be calculated. Obesity was defined as BMI ≥95th percentile for age and gender. Sedation-related outcomes, adverse events, and therapeutic interventions were compared between obese and nonobese patients.

RESULTS

For analysis, 28,792 records were eligible. A total of 5,153 patients (17.9%) were obese; they were predominantly male and older and had a higher median American Society of Anesthesiologists Physical Status classification (P < 0.001). Total adverse events were more common in obese patients (odds ratio [OR] 1.49, 95% confidence interval [1.31, 1.70]). Respiratory events (airway obstruction OR 1.94 [1.54, 2.44], oxygen desaturation OR 1.99 [1.50, 2.63], secretions OR 1.48 [1.01, 2.15], laryngospasm OR 2.30 [1.30, 4.05]), inability to complete the associated procedure (OR 1.96 [1.16, 3.30]), and prolonged recovery (OR 2.66 [1.26, 5.59]) were increased in obese patients. Obese patients more frequently required airway intervention including repositioning, suctioning, jaw thrust, airway adjuncts, and bag-valve-mask ventilation. Multivariate regression analysis demonstrated obesity to be independently associated with minor and moderate but not major adverse events.

CONCLUSIONS

Obesity is an independent risk factor for adverse respiratory events during procedural sedation and is associated with an increased frequency of airway interventions, suggesting that additional vigilance and expertise are required when sedating these patients.

A retrospective description of anesthetic medication dosing in overweight and obese children

INTRODUCTION

Pediatric obesity is a major health concern in the United States and as many as 34% of those who require general anesthesia are overweight or obese (OW). The lack of data and recommendations for dosing medications in obese children leaves significant gaps in the understanding of correct dosing in the clinical setting.

OBJECTIVE

To determine whether OW children were more likely to receive doses of medications outside the recommended range.

METHODS

Following IRB approval, patient medical records were queried to identify children 2 through 17 years who underwent noncardiac surgeries and received at least one medication of interest. Children with hepatic disease, renal disease, neurological impairment, sleep-disordered breathing, or missing height or weight measurements were excluded. Children were stratified into weight categories based on age and gender percentiles as per CDC guidelines. Those ≥85th percentile were classified as overweight/obese. Ideal and lean weight (for age, gender) were calculated. Drug doses were stratified as under-dosed (>10% below minimum recommended dose), overdosed (>10% above maximum recommended dose), or within recommended dose (dose ± 10%). Actual doses were compared to recommended doses as per actual, ideal, or lean weight (as recommended for specific drugs) in the overweight/obese groups vs the control weight (CW) group.

RESULTS

Ten thousand five hundred and nine doses were reviewed. Overweight/obese children were more likely to receive doses outside the recommended dose range than the CW group.

CONCLUSIONS

Overweight/obese children were more likely to receive doses of common anesthetic medications outside the recommended doses potentially adding risk of adverse outcomes in these children.

No association between obesity and post-tonsillectomy haemorrhage

Background:

The prevalence of overweight and obesity is increasing worldwide. The impact of overweight on post-tonsillectomy haemorrhage rates in children and adults is unclear.

Methods:

Body mass index and post-tonsillectomy haemorrhage were evaluated in all patients treated with tonsillectomy within one year in a tertiary referral centre. Bleeding episodes were categorised according to the Austrian Tonsil Study.

Results:

Between June 2011 and June 2012, 300 adults and children underwent tonsillectomy. Post-tonsillectomy haemorrhage occurred in 55 patients. Of those, 29 were type A (history of blood in saliva only, no active bleeding), 15 were type B (active bleeding, treatment under local anaesthesia) and 11 were type C (active bleeding, treatment under general anaesthesia). The return to operating theatre rate was 3.7 per cent. Post-tonsillectomy haemorrhage was more frequent in adolescents and adults than in children. Overweight or obesity was positively correlated with age. Post-tonsillectomy bleeding was recorded in 11.1 per cent of underweight patients, 18.9 per cent of normal weight patients and 18.7 per cent of overweight patients (p = 0.7). Data stratification (according to age and weight) did not alter the post-tonsillectomy bleeding risk (p = 0.8).

Conclusion:

Overweight or obesity did not increase the risk of post-tonsillectomy haemorrhage in either children or adults.

Pediatric airway management

Securing an airway is a vital task for the anesthesiologist. The pediatric patients have significant anatomical and physiological differences compared with adults, which impact on the techniques and tools that the anesthesiologist might choose to provide safe and effective control of the airway. Furthermore, there are a number of pathological processes, typically seen in the pediatric population, which present unique anatomical or functional difficulties in airway management. The presence of one of these syndromes or conditions can predict a "difficult airway." Many instruments and devices are currently available which have been designed to aid in airway management. Some of these have been adapted from adult designs, but in many cases require alterations in technique to account for the anatomical and physiological differences of the pediatric patient. This review focuses on assessment and management of pediatric airway and highlights the unique challenges encountered in children.

Appendicitis in obese children

During the past two decades, the incidence of childhood obesity has increased at alarming rates throughout the world. Obesity is associated with a variety of physiological changes that may impair a patient's response to surgery. With the rising rates of childhood obesity, pediatric surgeons must appreciate differences in the management and outcomes of these patients. Difficult physical examination, elevated inflammatory blood markers, and negative influence of obesity on the detection rate of the appendix on ultrasound have been reported causing diagnostic challenging of appendicitis in obese children. Moreover, obesity is associated with longer hospital stay and higher morbidity and minimal invasive techniques' superior outcomes over open technique in children undergoing appendectomy.

Preoperative evaluation, premedication, and induction of anesthesia in infants and children

PURPOSE OF REVIEW

Preparation for and induction of anesthesia in children has evolved significantly over the last decade, with particular reference to the reduction of perioperative anxiety reduction by nonpharmacologic and pharmacologic means. Several new large population studies and meta-analyses further scrutinize the current techniques.

RECENT FINDINGS

Many nonpharmacologic methods to reduce anxiety are effective λU similar to sedative premedications, with the exception of parent present induction of anesthesia. Healthcare providers can be taught to increase anxiety-reducing behaviors through an educational intervention. Clonidine and dexmedetomidine have many similar or superior qualities to midazolam.

SUMMARY

Larger studies still need to be conducted before wide-scale application of many nonpharmalogical interventions such as parental acupuncture. Similarly, more investigation should be done on outcomes such as onset, emergence, and discharge times, as well as the postoperative response with reference to emergence delirium and postoperative nausea and vomiting prevention to outline the differences among sedative premedications such as midazolam, clonidine, and dexmedetomidine.

Impact of obesity on drug metabolism and elimination in adults and children

The prevalence of obesity in adults and children is rapidly increasing across the world. Several general (patho)physiological alterations associated with obesity have been described, but the specific impact of these alterations on drug metabolism and elimination and its consequences for drug dosing remains largely unknown. In order to broaden our knowledge of this area, we have reviewed and summarized clinical studies that reported clearance values of drugs in both obese and non-obese patients. Studies were classified according to their most important metabolic or elimination pathway. This resulted in a structured review of the impact of obesity on metabolic and elimination processes, including phase I metabolism, phase II metabolism, liver blood flow, glomerular filtration and tubular processes. This literature study shows that the influence of obesity on drug metabolism and elimination greatly differs per specific metabolic or elimination pathway. Clearance of cytochrome P450 (CYP) 3A4 substrates is lower in obese as compared with non-obese patients. In contrast, clearance of drugs primarily metabolized by uridine diphosphate glucuronosyltransferase (UGT), glomerular filtration and/or tubular-mediated mechanisms, xanthine oxidase, N-acetyltransferase or CYP2E1 appears higher in obese versus non-obese patients. Additionally, in obese patients, trends indicating higher clearance values were seen for drugs metabolized via CYP1A2, CYP2C9, CYP2C19 and CYP2D6, while studies on high-extraction-ratio drugs showed somewhat inconclusive results. Very limited information is available in obese children, which prevents a direct comparison between data obtained in obese children and obese adults. Future clinical studies, especially in children, adolescents and morbidly obese individuals, are needed to extend our knowledge in this clinically important area of adult and paediatric clinical pharmacology.

My child is unique; the pharmacokinetics are universal

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

Perioperative management of the morbidly obese adolescent with heart failure undergoing bariatric surgery

The incidence and prevalence of adolescent obesity and adolescent heart failure are increasing, and anesthesiologists increasingly will encounter patients with both conditions. A greater understanding of the physiologic challenges of adolescent heart failure as they relate to the perioperative stressors of anesthesia and bariatric surgery is necessary to successfully manage the perioperative risks faced by this growing subpopulation. Here, we present a representative case of a morbidly obese adolescent with heart failure who underwent a laparoscopic bariatric operation and review the limited available literature on perioperative management in this age group. Specifically, we review evidence and offer recommendations related to preoperative evaluation, venous thromboembolism prophylaxis, positioning, induction, airway management, monitoring, anesthetic maintenance, ventilator management, and adverse effects of the pneumoperitoneum, rhabdomyolysis, and postoperative care.