Feasibility of calculating rocuronium dosage by skeletal muscle weight in patients with obesity

This study aimed to investigate the dose-response relationship of rocuronium administered based on skeletal muscle weight and to assess the feasibility of calculating rocuronium dosage by skeletal muscle weight in short surgeries for patients with obesity. This single-center, randomized controlled clinical trial included 71 patients with obesity aged 28-70 years, with body fat percentages (PBF) >20% in men and > 28% in women, ASA status I-III, scheduled for tracheoscopy. Patients were randomly allocated into two groups: skeletal muscle group (SM group) received rocuronium based on the skeletal muscle content (1.0 mg/kg, n = 31), and the conventional administration group (conventional group) received rocuronium based on total body weight (0.45 mg/kg, n = 30). General anesthesia was administered using the same protocol. Parameters recorded included patients' general condition, muscle relaxant usage, onset time of muscle relaxants, non-response time, clinical effect time, 75% recovery time, and recovery index. Additionally, occurrences of body movement, choking, and incomplete muscle relaxation during surgery were recorded. Compared to the conventional group, the SM group required significantly less rocuronium dosage, resulting in significantly lower non-response time, clinical effect time, 75% recovery time, and recovery index (p < 0.05), and the onset time is slightly longer. Neither group experienced body movement, choking, or incomplete muscle relaxation (p > 0.05). Utilizing skeletal muscle weight to calculate rocuronium dosage in short surgeries for patients with obesity can reduce dosage, shorten recovery time, and prevent residual muscle relaxation while achieving satisfactory muscle relaxation to meet surgical requirements.

Impact of Obesity on Hepatic Drug Clearance: What are the Influential Variables?

Drug clearance in obese subjects varies widely among different drugs and across subjects with different severity of obesity. This study investigates correlations between plasma clearance (CLp) and drug- and patient-related characteristics in obese subjects, and evaluates the systematic accuracy of common weight-based dosing methods. A physiologically-based pharmacokinetic (PBPK) modeling approach that uses recent information on obesity-related changes in physiology was used to simulate CLp for a normal-weight subject (body mass index [BMI] = 20) and subjects with various severities of obesity (BMI 25-60) for hypothetical hepatically cleared drugs with a wide range of properties. Influential variables for CLp change were investigated. For each drug and obese subject, the exponent that yields perfect allometric scaling of CLp from normal-weight subjects was assessed. Among all variables, BMI and relative changes in enzyme activity resulting from obesity proved highly correlated with obesity-related CLp changes. Drugs bound to α1-acid glycoprotein (AAG) had lower CLp changes compared to drugs bound to human serum albumin (HSA). Lower extraction ratios (ER) corresponded to higher CLp changes compared to higher ER. The allometric exponent for perfect scaling ranged from -3.84 to 3.34 illustrating that none of the scaling methods performed well in all situations. While all three dosing methods are generally systematically accurate for drugs with unchanged or up to 50% increased enzyme activity in subjects with a BMI below 30 kg/m2, in any of the other cases, information on the different drug properties and severity of obesity is required to select an appropriate dosing method for individuals with obesity.

Model-Informed Approaches to Support Drug Development for Patients With Obesity: A Regulatory Perspective

Obesity, which is defined as having a body mass index of 30 kg/m2 or greater, has been recognized as a serious health problem that increases the risk of many comorbidities (eg, heart disease, stroke, and diabetes) and mortality. The high prevalence of individuals who are classified as obese calls for additional considerations in clinical trial design. Nevertheless, gaining a comprehensive understanding of how obesity affects the pharmacokinetics (PK), pharmacodynamics (PD), and efficacy of drugs proves challenging, primarily as obese patients are seldom selected for enrollment at the early stages of drug development. Over the past decade, model-informed drug development (MIDD) approaches have been increasingly used in drug development programs for obesity and its related diseases as they use and integrate all available sources and knowledge to inform and facilitate clinical drug development. This review summarizes the impact of obesity on PK, PD, and the efficacy of drugs and, more importantly, provides an overview of the use of MIDD approaches in drug development and regulatory decision making for patients with obesity: estimating PK, PD, and efficacy in specific dosing scenarios, optimizing dose regimen, and providing evidence for seeking new indication(s). Recent review cases using MIDD approaches to support dose selection and provide confirmatory evidence for effectiveness for patients with obesity, including pediatric patients, are discussed. These examples demonstrate the promise of MIDD as a valuable tool in supporting clinical trial design during drug development and facilitating regulatory decision-making processes for the benefit of patients with obesity.

The Importance of Assessing Drug Pharmacokinetics and Pharmacodynamics in the Obese Population During Drug Development

Obesity remains a US national health crisis and a growing concern worldwide. Concerningly, individuals who are obese are at an increased risk for comorbid diseases that include, but are not limited to, hypertension, diabetes, cardiovascular disease, and cancer. Beyond the risk for developing these conditions, obesity may also impact the pharmacological activity of the therapies being used to treat them and other disease states. The pharmacokinetics (PK), pharmacodynamics (PD), safety, and efficacy of therapies, both currently marketed and under clinical development, may be directly impacted by the physiological alterations that occur secondary to the occurrence of chronic excess body weight. The increased prevalence of this disease should not be ignored. Both private and federal institutions involved in drug research and development should consider, as appropriate, a greater inclusion of individuals who are obese in clinical trials throughout the entirety of drug development, and leverage the available PK, PD, safety, and efficacy data to make more informed dosing recommendations.

Is There a Need for a Dedicated Pharmacokinetic Trial for a Drug in Obese Populations? A Drug Prioritization Decision Tree Framework

Obesity is a growing global health concern associated with high comorbidity rates, leading to an increasing number of patients who are obese requiring medication. However, clinical trials often exclude or under-represent individuals who are obese, creating the need for a methodology to adjust labeling to ensure safe and effective dosing for all patients. To address this, we developed a 2-part decision tree framework to prioritize drugs for dedicated pharmacokinetic studies in obese subjects. Leveraging current drug knowledge and modeling techniques, the decision tree system predicts expected exposure changes and recommends labeling strategies, allowing stakeholders to prioritize resources toward the drugs most in need. In a case study evaluating 30 drugs from literature across different therapeutic areas, our first decision tree predicted the expected direction of exposure change accurately in 73% of cases. We conclude that this decision tree system offers a valuable tool to advance research in obesity pharmacology and personalize drug development for patients who are obese, ensuring safe and effective medication.

Effect of inspiratory muscle training on hypoxemia in obese patients undergoing painless gastroscopy: protocol for a single-center, double-blind, randomized controlled trial

Introduction

Obese patients who undergo painless gastroscopy are particularly prone to suffer from upper airway obstruction, respiratory depression, and subsequent hypoxemia. Despite adequate preoxygenation, the incidence of hypoxemia remains high. Recently, inspiratory muscle training (IMT) has been considered to be a promising strategy to increase respiratory muscle strength and endurance with the attendant improvement of pulmonary function. However, it remains unclear whether IMT is associated with a lower rate of hypoxemia in obese patients during this sedative procedure. This study aims to investigate the effectiveness of IMT used in obese patients who are scheduled for selective painless gastroscopy.

Methods and analysis

This prospective, randomized controlled trial (RCT) will enroll 232 obese patients with a body mass index (BMI) of 35-39.9 kg·m-2 who undergo painless gastroscopy at the First Affiliated Hospital of Xiamen University. Subjects will be randomly assigned to two groups with a 1:1 ratio. Participants in both groups will receive IMT for 4 weeks prior to gastroscopy. The intervention group will receive IMT with a load of 30% of the maximal inspiratory pressure (Pi(max)) in the first week, with an increase of 10% per week since the following week, while the counterparts in the control group will not receive any load during the 4-week IMT. The primary outcome is the incidence of hypoxemia during painless gastroscopy. Secondary outcomes include the need for airway maneuvers, blood pressure changes, sleep quality assessment, pro-inflammatory cytokines levels, and monitoring of adverse events.

Discussions

The outcomes of this study will offer invaluable guidance for the clinical implementation of IMT as a potential non-invasive preventive measure. Additionally, it stands to enrich our comprehension of anesthesia management and airway-related challenges in obese patients undergoing procedural sedation, which we anticipate will further contribute to addressing the turnaround concerns within high-volume, swiftly paced ambulatory endoscopy centers.

Ethics and dissemination

This study has been approved by the Ethics Committee of the First Affiliated Hospital of Xiamen University (2022, No.091). The results will be submitted for publication in peer-reviewed journals.

Trial registration number

China Clinical Trial Center (ChiCTR2200067041).

Adherence to Sedation Targets With Weight-Based Propofol and Dexmedetomidine in Patients With Morbid Obesity

BACKGROUND

Propofol and dexmedetomidine are routinely used in intensive care units (ICUs). Both are lipophilic, potentially leading to accumulation in adipose tissue. Limited evidence exists on what body weight to utilize in patients with morbid obesity.

OBJECTIVE

The purpose of this research was to evaluate the safety and efficacy of weight-based sedation with propofol and dexmedetomidine in ICU patients with morbid obesity.

METHODS

Retrospective review of ICU patients admitted from January 2018 to January 2020 who were sedated for ≥48 hours was performed. The primary outcome was the percentage of time within target sedation during the first 48 hours, stratified by body mass index (BMI) <40 or ≥40 kg/m². Additional outcomes included adverse events and the infusion rate to achieve target sedation. Data were evaluated using descriptive statistics.

RESULTS

A total of 80 patients were analyzed. Patients on propofol with a BMI <40 kg/m² were in their target Richmond Agitation-Sedation Scale (RASS) 11.7% versus 16.1% with a BMI ≥40 kg/m² (P = .580). Patients with a BMI <40 kg/m² on dexmedetomidine were in their target RASS 27.6% versus 10.7% with a BMI ≥40 kg/m² (P = .053).

CONCLUSION AND RELEVANCE

Body mass index did not significantly alter propofol target sedation attainment. However, patients with morbid obesity on dexmedetomidine demonstrated significantly less time in target sedation. An actual body weight dosing strategy of these drugs did not achieve desired target sedation for those with a BMI ≥40 versus BMI <40 kg/m². These findings support future research on the optimal sedation dosing strategy in this patient population.

Effects of opioid-free propofol or remimazolam balanced anesthesia on hypoxemia incidence in patients with obesity during gastrointestinal endoscopy: A prospective, randomized clinical trial

There are presently no consensuses on the optimal sedation strategy for obese patients during gastrointestinal endoscopy. This study aim to explore the effects of opioid-free propofol or remimazolam balanced anesthesia on hypoxemia incidence in patients with obesity. A total of 264 patients were randomized to remimazolam + esketamine group (group R) or propofol + esketamine group (group P). Anesthesia in group P was administrated by propofol, esketamine and in group R by remimazolam, esketamine. The primary outcome was incidence of hypoxemia. Secondary outcomes were the time to loss of consciousness (LoC) and to recovery and the incidence of intraoperative and postoperative adverse reactions. We found the incidence of mild hypoxemia in group R was similar to that in group P (14.2% vs. 11.5%, p = 0.396). The incidence of severe hypoxemia in group R was significantly lower than Group P (4.2% vs. 9.2%, p = 0.019). The time to LoC in group R was longer than group P [Median (interquartile range, IQR): 53 s (45 to 61) vs. 50 s (42 to 54), p = 0.001]. The time to recovery from anesthesia in group R was less than group P [Median (IQR): 48 min (41 to 58) vs. 55.5 min (46 to 67), p<0.001]. There was no significant difference in the incidence of adverse events (p > 0.05 for all). We concluded that compared with propofol combined with esketamine, remimazolam combined with esketamine can reduce the incidence of severe hypoxemia during gastrointestinal endoscopy in obese patients. Clinical Trial Registration: www.chictr.org.cn, Identifier: ChiCTR2200065575.

Drug pharmacokinetics in the obese population: challenging common assumptions on predictors of obesity-related parameter changes

INTRODUCTION

Obesity is associated with many physiological changes. We review available evidence regarding five commonly accepted assumptions to a priori predict the impact of obesity on drug pharmacokinetics (PK).

AREAS COVERED

The investigated assumptions are: 1) lean body weight is the preferred descriptor of clearance and dose adjustments; 2) volume of distribution increases for lipophilic, but not for hydrophilic drugs; 3) CYP-3A4 activity is suppressed and UGT activity is increased, implying decreased and increased dose requirements for substrates of these enzyme systems, respectively; 4) glomerular filtration rate is enhanced, necessitating higher doses for drugs cleared through glomerular filtration; 5) drug dosing information from obese adults can be extrapolated to obese adolescents.

EXPERT OPINION

Available literature contradicts, or at least limits the generalizability, of all five assumptions. Clinical studies should focus on quantifying the impact of duration and severity of obesity on drug PK in adults and adolescents, and also include oral bioavailability and pharmacodynamics in these studies. Physiologically-based PK approaches can be used to predict PK changes for individual drugs, but can also be used to define in general terms based on patient characteristics and drug properties, when certain assumptions can or cannot be expected to be systematically accurate.

Influence of body fatness on propofol requirements for loss of consciousness in target-controlled infusion: A STROBE-compliant study

This prospective observational study evaluated the effects of body fat on the pharmacologic effect of propofol. Hundred patients aged 18 to 75 years who were scheduled to undergo orthopedic surgery under regional block were enrolled. All participants underwent bioelectrical impedance analysis and were allocated into 2 groups: the high and normal adiposity group, according to percent body fat. Following successful regional block, propofol was incrementally infused until loss of consciousness (LOC) with a target-controlled infusion pump. The effect-site concentration of propofol at LOC and the total infused dose of propofol per total body weight until LOC were recorded. At the end of the surgery, the infusion of propofol was stopped. The elapsed time to recovery of consciousness (ROC) and the effect-site concentration at ROC were recorded. These pharmacologic data were compared between 2 groups. The effect-site concentration of propofol at LOC (µg/mL) was significantly lower in the high adiposity group than in the normal group in both sexes (3.5 ± 0.4 vs 3.9 ± 0.6; P = .020 in males, and 3.4 [interquartile range: 2.9-3.5] vs 3.8 [interquartile range: 3.3-3.9]; P = .006 in females). Total dose per total body weight until LOC (mg/kg) were also significantly lower in the high adiposity group than in the normal group. There was no significant difference in the data related to ROC. The pharmacologic effects of propofol may be affected by the composition of body components. The concentration of propofol using a target-controlled infusion system may be diminished in patients with a high proportion of body fat.

Sleeve gastrectomy in the surgical management of obesity in Cameroon (a sub-Saharan country): A single-institute retrospective review of 30-day postoperative morbidity and mortality

BACKGROUND

METHODS

RESULTS

CONCLUSION

•

Sleeve gastrectomy is a safe procedure in a sub-Saharan African low setting.

•

Bleeding is the only intraoperative complication encountered in 14.3% of cases.

•

The prevalence of 30-day postoperative morbidity of sleeve gastrectomy is 38.1%.

•

Postoperative 30-day complications after sleeve gastrectomy are minor.

•

The 30-day postoperative mortality after sleeve gastrectomy is nil.

Body mass index and pharmacodynamics of target-controlled infusion of propofol: A prospective non-randomized controlled study

WHAT IS KNOWN AND OBJECTIVE

In our preliminary study, there were large individual variations at sedation levels during propofol target-controlled infusion (TCI). The present study aimed to assess the effects of body mass index (BMI) on the pharmacodynamic index of propofol TCI.

METHODS

This prospective, non-randomized controlled trial evaluated 175 female patients undergoing breast lumpectomy. Anesthesia was induced with propofol using the TCI system embedded Schnider model. The effect compartment concentration was set to 3 μg/ml, and the start time of infusion was recorded. When the target concentration reached 3 μg/ml, the patient could not be awakened (Ramsay sedation score ≥4), and when the Bispectral Index (BIS) was <60, the infusion was discontinued, and the time point was recorded. The observation end-point was set at the Observer's Assessment of Alertness/Sedation (OAA/S) score of <4. The correlation between the BMI and the pharmacodynamic index of propofol was evaluated.

RESULTS AND DISCUSSION

Propofol induction time was significantly correlated with the BMI (p < 0.001). The induction time of the underweight subjects was 10.14 ± 2.19 min, which was remarkably higher than that of normal weight (6.48 ± 3.44 min) and overweight (4.75 ± 2.53 min) individuals (p < 0.001). There were still significant differences after multivariable-adjusted regressions (p < 0.001). There were no significant differences in recovery time and sedative effect indicators, such as Ramsay score, BIS value, and effect compartment concentration, between the three groups (p > 0.05 for all).

WHAT IS NEW AND CONCLUSION

These results suggest that the BMI is one of the critical factors affecting the pharmacodynamic index of propofol TCI, and the induction time decreased progressively with increasing BMI. The Schnider model might underpredict doses of propofol for underweight individuals.

Obesity and anesthetic pharmacology: simulation of target-controlled infusion models of propofol and remifentanil

The prevalence of obesity is increasing, resulting in an increase in the number of surgeries performed to treat obesity and diseases induced by obesity. The associated comorbidities as well as the pharmacokinetic and pharmacodynamic changes that occur in obese patients make it difficult to control the appropriate dose of anesthetic agents. Factors that affect pharmacokinetic changes include the increase in adipose tissue, lean body weight, extracellular fluid, and cardiac output associated with obesity. These physiological and body compositional changes cause changes in the pharmacokinetic and pharmacodynamic parameters. The increased central volume of distribution and alterations in the clearance of drugs affect the plasma concentration of propofol and remifentanil in the obese population. Additionally, obesity can affect pharmacodynamic properties, such as the 50% of maximal effective concentration and the effect-site equilibration rate constant (ke0). Conducting a simulation of target-controlled infusions based on pharmacokinetic and pharmacodynamic models that include patients that are obese can help clinicians better understand the pharmacokinetic and pharmacodynamic changes of anesthetic drugs associated with this population.

Anesthesia for Patients Who Self-Report Cannabis (Marijuana) Use Before Esophagogastroduodenoscopy: A Retrospective Review

Increasing numbers of patients are using cannabis before procedures that require anesthesia. This study set out to examine the impact of cannabis use on anesthetic agent requirements, associated cardiac and respiratory morbidity, and overall satisfaction levels in patients undergoing esophagogastroduodenoscopy (EGD). This involved a retrospective review of patients undergoing EGD at a single center. Fortyseven, self-reported cannabis users were identified and 23 were successfully cross-matched with control participants for comparison purposes. The Wilcoxon signed rank test was used to evaluate differences in propofol administration between the 2 groups, and the McNemar test was used to test for differences in fentanyl and ketamine administration. No statistically significant differences were observed in propofol, fentanyl, or ketamine administration in the cannabis group compared with the control group. No adverse cardiac or respiratory events were reported within 30 days for either group. This study was specific to EGD procedures of short duration, and larger studies are needed to confirm results of no consequence in cannabis users undergoing anesthesia. Future studies should consider cannabis users who undergo anesthesia for diverse procedure types of various durations.

Pharmacokinetics of Sugammadex Dosed by Actual and Ideal Body Weight in Patients With Morbid Obesity Undergoing Surgery

This analysis of a published study (NCT03346070) evaluated the pharmacokinetics (PKs) of sugammadex dosed by actual body weight (ABW) or ideal body weight (IBW) for reversal of moderate or deep neuromuscular block (M-NMB or D-NMB) in adults with morbid obesity. Adults with body mass index ≥ 40 kg/m² , ABW ≥ 100 kg, and American Society of Anesthesiologists (ASA) Class 3 were stratified by NMB agent (rocuronium or vecuronium) and randomized 1:1:1:1:1 to (i) M-NMB, sugammadex 2 mg/kg ABW; (ii) M-NMB, sugammadex 2 mg/kg IBW; (iii) M-NMB, neostigmine 5 mg + glycopyrrolate 1 mg; (iv) D-NMB, sugammadex 4 mg/kg ABW; and (v) D-NMB, sugammadex 4 mg/kg IBW. Plasma samples for sugammadex quantification were collected predose, 2, 5, 15, 60, and 120 minutes, and 4, 6 hours postdose. Natural log PK parameters were analyzed using linear fixed effect model with treatment, mode (ABW and IBW), and mode by treatment interaction as fixed terms. The sugammadex PK profile showed rapid distribution followed by monophasic decline consistent with a two-compartment model examined by dose and mode. Absolute sugammadex exposures were ~ 50% higher in the ABW vs. IBW group; dose-independent parameters (clearance and volume of distribution) and terminal half-life remained constant. Sugammadex PK parameter values increased in dose-dependent, linear manner following dosing by ABW or IBW, such that PK continues to be predictive across the clinical dose range. In conjunction with previously published results showing faster recovery with ABW vs. IBW dosing across NMB agent and depth of NMB, these PK findings continue to support dosing by ABW in patients with morbid obesity irrespective of depth of NMB.

Investigation on the metabolic characteristics of isobavachin in Psoralea corylifolia L. (Bu-gu-zhi) and its potential inhibition against human cytochrome P450s and UDP-glucuronosyltransferases

OBJECTIVES

Isobavachin is a phenolic with anti-osteoporosis activity. This study aimed to explore its metabolic fates in vivo and in vitro, and to investigate the potential drug-drug interactions involving CYPs and UGTs.

METHODS

Metabolites of isobavachin in mice were first identified and characterized. Oxidation and glucuronidation study were performed using liver and intestine microsomes. Reaction phenotyping, activity correlation analysis and relative activity factor approaches were employed to identify the main CYPs and UGTs involved in isobavachin metabolism. Through kinetic modelling, inhibition mechanisms towards CYPs and UGTs were also explored.

KEY FINDINGS

Two glucuronides (G1 - G2) and three oxidated metabolites (M1 - M3) were identified in mice. Additionally, isobavachin underwent efficient oxidation and glucuronidation by human liver microsomes and HIM with CL_int values from 5.53 to 148.79 μl/min per mg. CYP1A2, 2C19 contributed 11.3% and 17.1% to hepatic metabolism of isobavachin, respectively, with CL_int values from 8.75 to 77.33 μl/min per mg. UGT1As displayed CL_int values from 10.73 to 202.62 μl/min per mg for glucuronidation. Besides, significant correlation analysis also proved that CYP1A2, 2C19 and UGT1A1, 1A9 were main contributors for the metabolism of isobavachin. Furthermore, mice may be the appropriate animal model for predicting its metabolism in human. Moreover, isobavachin exhibited broad inhibition against CYP2B6, 2C9, 2C19, UGT1A1, 1A9, 2B7 with K_i values from 0.05 to 3.05 μm.

CONCLUSIONS

CYP1A2, 2C19 and UGT1As play an important role in isobavachin metabolism. Isobavachin demonstrated broad-spectrum inhibition of CYPs and UGTs.

Drug dosing in the critically ill obese patient-a focus on sedation, analgesia, and delirium

Practice guidelines provide clear evidence-based recommendations for the use of drug therapy to manage pain, agitation, and delirium associated with critical illness. Dosing recommendations however are often based on strategies used in patients with normal body habitus. Recommendations specific to critically ill patients with extreme obesity are lacking. Nonetheless, clinicians must craft dosing regimens for this population. This paper is intended to help clinicians design initial dosing regimens for medications commonly used in the management of pain, agitation, and delirium in critically ill patients with extreme obesity. A detailed literature search was conducted with an emphasis on obesity, pharmacokinetics, and dosing. Relevant manuscripts were reviewed and strategies for dosing are provided.

Propofol Sedation for Intragastric Balloon Removal: Looking for the Optimal Body Weight Descriptor

AIM

Sedation is considered as a prerequisite for the safe and effective conclusion of Bioenterics Intragastric Balloon (BIB) removal (our aim was to ascertain the most appropriate body size scalars for propofol dosing and assess the efficacy and safety of a sedative approach involving the infusion of propofol for BIB removal.

METHOD

Retrospective analysis of prospectively collected data of 414 adults scheduled to undergo BIB removal. Our primary end-point was to delineate the relationship between propofol dosing and body size descriptors namely body mass index, total body weight, ideal body weight, lean body weight (LBW) and normalized LBW. Sedative efficacy of this practice, anesthesia or procedural-related adverse events and patients' satisfaction level served as secondary outcome parameters.

RESULTS

Propofol dose (mg/kg/min) was positively related to all body weight descriptors in an important manner (p < 0.001). Among them, LBW was singled out as the body size descriptor to best capture the appropriate needs of propofol (R² = 0.432; p = 0.000). Hypoxemia, hemodynamic compromise, gastroesophageal reflux or moderate movement occurred rarely; all of them were readily reversed. The majority of participants had no recollection of the noxious phase of the procedure or declared at least adequately satisfied from the experience (84% and 95%, respectively).

CONCLUSION

LBW could serve as relatively more accurate dosing scalar compared to actual or ideal body weight descriptors, in obese individuals undergoing BIB removal under propofol sedation. The conscious/deep sedation based on propofol infusion emerges as a feasible and efficacious sedative approach for this procedure.

Choice of Perioperative Anesthetic Medications in Patients Undergoing Bariatric Surgery

The prevalence of obesity is increasing globally. Rational perioperative anesthetic drug selection and administration require knowledge of how obesity interacts with those drugs. In this review, we summarize different aspects of the anesthetic agents, including pharmacokinetics (PK), pharmacodynamics (PD) and clinical application of the most commonly used medications with particular focus on the enhanced recovery of the obese patient.

Pharmacokinetics and Pharmacodynamics of Drugs in Obese Pediatric Patients: How to Map Uncharted Clinical Territories

Clinicians are increasingly faced with challenges regarding the pharmacological treatment of obese pediatric patients. To provide guidance for these treatments, a better understanding of the impact of obesity on pharmacological processes in children is needed. Results on pharmacological studies in adults show however ambiguous patterns regarding the impact of obesity on ADME processes or on drug pharmacodynamics. Additionally, based on the limited research performed in obese pediatric patients, it becomes clear that findings from obese adults cannot be expected to always translate directly to similar findings in obese children. To improve knowledge on drug pharmacology in obese pediatric patients, studies should focus on quantifying the impact of maturation, obesity, and other relevant variables on primary pharmacological parameters and on disentangling systemic (renal and/or hepatic) and presystemic (gut and/or first-pass hepatic) clearance. For this, data is required from well-designed clinical trials that include patients with not only a wide range in age but also a range in excess body weight, upon oral and intravenous dosing. Population modelling approaches are ideally suitable for this purpose and can also be used to link the pharmacokinetics to pharmacodynamics and to derive drug dosing regimens. Generalizability of research findings can be achieved by including mechanistic aspects in the data analysis, for instance, using either extrapolation approaches in population modelling or by applying physiologically based modelling principles. It is imperative that more and smarter studies are performed in obese pediatric patients to provide safe and effective treatment for this special patient population.

Drug Dose Selection in Pediatric Obesity: Available Information for the Most Commonly Prescribed Drugs to Children

Obesity rates continue to rise in children, and little guidance exists regarding the need for adjustment away from total body weight-based doses for those prescribing drugs to this population of children. A majority of drugs prescribed to children with obesity result in either sub-therapeutic or supra-therapeutic concentrations, placing these children at risk for treatment failure and drug toxicities. In this review, we highlight available obesity-specific pharmacokinetic and dosing information for the most frequently prescribed drugs to children in the inpatient and outpatient clinical settings. We also comment on available dosing recommendations for drugs prescribed to treat common pediatric obesity-related comorbidities. This review highlights that there is no safe or proven 'rule of thumb,' for dosing drugs for children with obesity, and a striking lack of pharmacokinetic data to support the creation of dosing guidelines for children with obesity for the most commonly prescribed drugs. It is important that those prescribing for children with obesity are aware of these gaps in knowledge and of potential drug treatment failure or adverse events related to drug toxicity as a result of these knowledge gaps. Until more data are available, we recommend close monitoring of drug response and adverse events in children with obesity receiving commonly prescribed drugs.

Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea

The purpose of the Society of Anesthesia and Sleep Medicine Guideline on Intraoperative Management of Adult Patients With Obstructive Sleep Apnea (OSA) is to present recommendations based on current scientific evidence. This guideline seeks to address questions regarding the intraoperative care of patients with OSA, including airway management, anesthetic drug and agent effects, and choice of anesthesia type. Given the paucity of high-quality studies with regard to study design and execution in this perioperative field, recommendations were to a large part developed by subject-matter experts through consensus processes, taking into account the current scientific knowledge base and quality of evidence. This guideline may not be suitable for all clinical settings and patients and is not intended to define standards of care or absolute requirements for patient care; thus, assessment of appropriateness should be made on an individualized basis. Adherence to this guideline cannot guarantee successful outcomes, but recommendations should rather aid health care professionals and institutions to formulate plans and develop protocols for the improvement of the perioperative care of patients with OSA, considering patient-related factors, interventions, and resource availability. Given the groundwork of a comprehensive systematic literature review, these recommendations reflect the current state of knowledge and its interpretation by a group of experts at the time of publication. While periodic reevaluations of literature are needed, novel scientific evidence between updates should be taken into account. Deviations in practice from the guideline may be justifiable and should not be interpreted as a basis for claims of negligence.

Postoperative nausea and vomiting in bariatric surgery in comparison to non-bariatric gastric surgery

Introduction

Postoperative nausea and vomiting (PONV) are complications of general anesthesia. Patient-specific factors, type of surgery and a variety of drugs determine the frequency. Clinical experience shows nausea and vomiting to be very frequent in morbidly obese patients undergoing bariatric surgery.

Aim

To detect the onset and extent of nausea and vomiting in the group of morbidly obese patients undergoing laparoscopic bariatric surgery.

Material and methods

We conducted a retrospective data bank analysis (since 2004) of all patients with body mass index > 35 kg/m² undergoing laparoscopic bariatric surgery in comparison to patients with a body mass index < 35 kg/m² undergoing gastric surgery. Propensity score matching was applied to minimize bias effects. The frequency of postoperative nausea was defined as the primary outcome parameter.

Results

One hundred and thirty-eight patients were included. There was a significant difference between the morbidly obese group and the control group concerning the frequency of postoperative nausea (15.9% vs. 55.1%; p < 0.001). In patients receiving volatile anesthetics a significant difference between groups concerning frequency of PONV was not observed. Intravenous anesthetics were suitable to reduce PONV in the control group but not in the morbidly obese group (12.5% vs. 56.8%, p < 0.001). With given prophylaxis PONV events still occurred in 15.6% vs. 48.8% (p = 0.003).

Conclusions

Morbidly obese patients undergoing laparoscopic bariatric surgery are at higher risk of suffering from PONV than non-morbidly obese patients. To reduce the PONV incidence in morbidly obese patients, further research, especially focusing on more efficient use of antiemetic drugs, seems to be necessary.

Characterization of cardiovascular depression effect for propofol during anesthesia induction period on morbidly obese patients

This study aims to determine the pharmacodynamics (PD) effect (measured by cardiovascular depression) of propofol during anesthesia induction period on morbidly obese (MO) patients. Four hemodynamics indexes [i.e., three indexes about blood pressure and cardiac output (CO)] representing cardiovascular function were measured. Pharmacokinetic/pharmacodynamic (PK/PD) modeling was performed by population analysis to obtain PD parameters. Two propofol dosing scalars, namely, dosing based on total body weight (TBW) or lean body weight (LBW), were used for MO subjects. The PD data were well described by a PK/PD model. Blood pressure and CO were rapidly decreased within one minute after intravenous injection of propofol (2 mg/kg). TBW group showed significantly lower blood pressure and CO values at and 1 min after propofol administration compared with the control group, whereas the control and LBW groups had similar PD profiles. In addition, the propofol EC₅₀ value was significantly decreased in MO patients, whereas all other PD parameters were similar between control and MO subjects. This change indicated that propofol potency and/or sensitivity was increased in MO subjects. For MO patients, dosing of propofol based on LBW rather than TBW would be a safer choice due to a less cardiovascular depression effect.

Obesity and drug pharmacology: a review of the influence of obesity on pharmacokinetic and pharmacodynamic parameters

INTRODUCTION

The rising prevalence of obesity confronts clinicians with dosing problems in the (extreme) overweight population. Obesity has a great impact on key organs that play a role in the pharmacokinetics (PK) and pharmacodynamics (PD) of drugs, however the ultimate impact of these changes on how to adapt the dose may not always be known. Areas covered: In this review, physiological changes associated with obesity are discussed. An overview is provided on the alterations in absorption, distribution, drug metabolism and clearance in (morbid) obesity focusing on general principles that can be extracted from pharmacokinetic studies. Also, relevant pharmacodynamic considerations in obesity are discussed. Expert opinion: Over the last two decades, increased knowledge is generated on PK and PD in obesity. Future research should focus on filling in the knowledge gaps that remain, especially in connecting obesity-related physiological changes with changes in PK and/or PD and vice versa. Ultimately, this knowledge can be used to develop physiologically based PK and PD models on the basis of quantitative systems pharmacology principles. Moreover, efforts should focus on thorough prospective evaluation of developed model-based doses with subsequent implementation of these dosing recommendations in clinical practice.

Comparison of Changes in Respiratory Dynamics Immediately After the Start of Propofol Sedation With or Without Midazolam

PURPOSE

The aim of this study was to compare changes in respiratory dynamics starting immediately after administration of propofol alone or a combination of propofol and midazolam.

MATERIALS AND METHODS

Twenty-seven healthy adult volunteers participated in a randomized crossover study of undergoing sedation with propofol alone (P group) or with a combination of propofol and midazolam (PM group). In the P group, continuous infusion of propofol through a target-controlled infusion (TCI) pump was started with the target effect site (ES) concentration set at 1.2 μg/mL. In the PM group, participants received a bolus administration of midazolam 0.02 mg/kg simultaneously with the start of continuous infusion of propofol through a TCI pump with the target ES concentration set at 0.8 μg/mL. The variables measured included the bispectral index (BIS) value, tidal volume (VT), percutaneous arterial oxygen saturation (SpO₂), respiratory rate (RR), end-tidal carbon dioxide tension (ETCO₂), estimated ES propofol concentration, and minute volume.

RESULTS

BIS value, VT, SpO₂, and ETCO₂ decreased after sedative administration in the 2 groups. RR increased in the 2 groups. These changes occurred sooner in the PM group than in the P group. The ratio of change in VT to change in BIS value decreased in the 2 groups and was markedly smaller in the PM group than in the P group. Ratios of changes in SpO₂, RR, and ETCO₂ to change in BIS value increased in the 2 groups and were larger in the PM group than in the P group.

CONCLUSION

Changes in respiratory dynamics occurred sooner in the PM group than in the P group. In the PM group, although VT began to decrease before the change in BIS value, the increase in RR caused the rate of decrease in SpO₂ to be smaller than the rate of decrease in BIS value.

Perioperative Pharmacologic Considerations in Obesity

Obesity has increased in incidence worldwide. Along with the increased number of obese patients, comorbid conditions are also more prevalent in this population. Obesity leads to changes in the physiology of patients along with an altered response to pharmacologic therapy. Vigilant perioperative physicians must be aware of the unique characteristics of administered agents in order to appropriately provide anesthetic care for obese patients. Because of the variability in tissue content in obese patients and changes in pharmacokinetic modeling, a one-size-fits-all approach is not justified and a more sophisticated and prudent approach is indicated.