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

Extrapolation of Midazolam Disposition in Neonates Using Physiological-Based Pharmacokinetic/Pharmacodynamic Modeling

There is a shortage of data in clinical studies of neonatal populations, which often utilize extrapolation strategies and model simulation techniques to support drug development and clinical applications. This study established an adult physiological-based pharmacokinetic/pharmacodynamic (PBPK/PD) model in the modeling software and extended it to neonates using pediatric extrapolation strategies based on maturation formulas for plasma albumin and CYP3A4/5. The neonatal model was then utilized to simulate midazolam dosage regimens for sedation in newborns. Individualized validation for adults indicated that 95.1% of predicted concentration values and all area under curve (AUC) values fell within a 2-fold range. The extrapolated neonatal model showed 84.4% of predicted concentrations within 2-fold, an absolute average fold error (AAFE) valuen <2, and an average fold error (AFE) value between 0.5 and 1.5, confirming the model's adequacy. The validated neonatal PBPK/PD model indicated that virtual term neonates maintained the target plasma concentration for 25 hours with the recommended dosage (0.06 mg/kg/h, intravenous infusion 12 hours). Premature infants may require a slightly higher dose than the label's recommendation (0.03 mg/kg/h, intravenous infusion 12 hours). Our findings recommend this research strategy based on extrapolation and model simulation for drug dose prediction and optimization in the neonatal population.

Pharmacokinetic pharmacodynamic modeling of analgesics and sedatives in children

Pharmacokinetic pharmacodynamic modeling is an important tool which uses statistical methodology to provide a better understanding of the relationship between concentration and effect of drugs such as analgesics and sedatives. Pharmacokinetic pharmacodynamic models also describe between-subject variability that allows identification of subgroups and dose adjustment for optimal pain management in individual patients. This approach is particularly useful in the pediatric population, where most drugs have received limited evaluation and dosing is extrapolated from adult practice. In children, the covariates of weight and age are used to describe size- and maturation-related changes in pharmacokinetics. It is important to consider both size and maturation in order to develop an accurate model and determine the optimal dose for different age groups. An adequate assessment of analgesic and sedative effect using pain scales or brain activity measures is essential to build reliable pharmacokinetic pharmacodynamic models. This is often challenging in children due to the multidimensional nature of pain and the limited sensitivity and specificity of some measurement tools. This review provides a summary of the pharmacokinetic and pharmacodynamic methodology used to describe the dose-concentration-effect relationship of analgesics and sedation in children, with a focus on the different pharmacodynamic endpoints and the challenges of pharmacodynamic modeling.

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.

Sleep cycle in children with severe acute bronchopneumonia during mechanical ventilation at different depths of sedation

BACKGROUND

To investigate the characteristics of sleep cycle in children with severe acute bronchopneumonia treated with invasive mechanical ventilation at different sedation depths.

METHODS

We included 35 pediatric patients with severe acute bronchopneumonia treated using mechanical ventilation in Pediatric Intensive Care Unit of Shengjing Hospital of China Medical University. They were divided into deep sedation group (n = 21; ramsay score 5-6) and light sedation group (n = 14; ramsay score3-4) based on sedation depth achieved during mechanical ventilation. Long-term video electroencephalography (EEG) monitoring was performed within the first 24 h after starting mechanical ventilation and after weaning from mechanical ventilation and discontinuing sedatives and analgesics. The results were analyzed and compared with those of normal children to analyze changes in sleep cycle characteristics at different sedation depths and mechanical ventilation stages.

RESULTS

There were 29 cases altered sleep architecture. The deep sedation group had a significantly higher incidence of sleep architecture altered, total sleep duration, and non-rapid eye movement sleep-1 (NREM-1) loss incidence than the light sedation group. Moreover, the deep sedation group had a significantly lower awakening number and rapid eye movement sleep (REM) percentage than the light sedation group. The sleep cycle returned to normal in 27 (77%) patients without NREM-1 or REM sleep loss.

CONCLUSIONS

Deep sedation during mechanical ventilation allows longer total sleep duration, fewer awakenings, and an increased deep sleep proportion, but sleep architecture is severely altered. After weaning from mechanical ventilation and sedative discontinuation, lightly sedated children exhibit better sleep 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.

High sedation needs of critically ill COVID-19 ARDS patients-A monocentric observational study

BACKGROUND

Therapy of severely affected coronavirus patient, requiring intubation and sedation is still challenging. Recently, difficulties in sedating these patients have been discussed. This study aims to describe sedation practices in patients with 2019 coronavirus disease (COVID-19)-induced acute respiratory distress syndrome (ARDS).

METHODS

We performed a retrospective monocentric analysis of sedation regimens in critically ill intubated patients with respiratory failure who required sedation in our mixed 32-bed university intensive care unit. All mechanically ventilated adults with COVID-19-induced ARDS requiring continuously infused sedative therapy admitted between April 4, 2020, and June 30, 2020 were included. We recorded demographic data, sedative dosages, prone positioning, sedation levels and duration. Descriptive data analysis was performed; for additional analysis, a logistic regression with mixed effect was used.

RESULTS

In total, 56 patients (mean age 67 (±14) years) were included. The mean observed sedation period was 224 (±139) hours. To achieve the prescribed sedation level, we observed the need for two or three sedatives in 48.7% and 12.8% of the cases, respectively. In cases with a triple sedation regimen, the combination of clonidine, esketamine and midazolam was observed in most cases (75.7%). Analgesia was achieved using sufentanil in 98.6% of the cases. The analysis showed that the majority of COVID-19 patients required an unusually high sedation dose compared to those available in the literature.

CONCLUSION

The global pandemic continues to affect patients severely requiring ventilation and sedation, but optimal sedation strategies are still lacking. The findings of our observation suggest unusual high dosages of sedatives in mechanically ventilated patients with COVID-19. Prescribed sedation levels appear to be achievable only with several combinations of sedatives in most critically ill patients suffering from COVID-19-induced ARDS and a potential association to the often required sophisticated critical care including prone positioning and ECMO treatment seems conceivable.

Development of a Chinese Version of the State Behavioral Scale for Mechanically Ventilated Children

PURPOSE

To develop a Chinese version of the State Behavioral Scale (SBS-C) and to evaluate its reliability and validity for sedation assessment in mechanically ventilated children in China.

DESIGN AND METHODS

Cross-sectional survey design was used in a two-part study of mechanically ventilated children, aged 6 weeks to 6 years. A total 172 children and 145 children were recruited from Jan-Dec 2017 and Jan-Dec 2018, respectively, at a tertiary care pediatric hospital in southeast China. Following translation of the scale, the content validity was established by the content validity index, internal consistency was established using Cronbach's α, and construct validity was confirmed by correlation with a similar well-recognized scale, the COMFORT Scale-Chinese version (CS-C).

RESULTS

The content validity index for the seven scale dimensions ranged from 0.83 to 1.0 and for the full scale was 0.932. In the first study, Cronbach's α for the full SBS-C was 0.986 and for the seven scale dimensions ranged from 0.973 to 0.983; similarly, in the second study, Cronbach's α for the full scale was 0.983 and for the seven dimensions ranged from 0.977 to 0.987. The correlation coefficient between scores of the SBS-C and the CS-C was 0.919 (P < .01).

CONCLUSIONS

The SBS-C is valid, reliable, and responsive and is suitable for assessing sedation in mechanically ventilated children in China.

IMPLICATIONS FOR PRACTICE

The SBS-C can be used for sedation assessment in mechanically ventilated children in China, guiding decision making and the provision of care, and optimizing patient safety.

Safety of clonidine used for long-term sedation in paediatric intensive care: A systematic review

AIM

Although not approved, the α-adrenoceptor agonist clonidine is considered an option for long-term sedation protocols in paediatric intensive care. We reviewed adverse effects of clonidine occurring in this indication.

METHODS

Relevant literature was systematically identified from PubMed and Embase. We included interventional and observational studies on paediatric patients admitted to intensive care units and systemically long-term sedated with clonidine-containing regimes. In duplicates, we conducted standardised and independent full-text assessment and extraction of safety data.

RESULTS

Data from 11 studies with 909 patients were analysed. The studies were heterogeneous regarding patient characteristics (age groups, comorbidity, or comedication) and sedation regimes (dosage, route, duration, or concomitant sedatives). Just four randomised controlled trials (RCTs) and one observational study had comparison groups, using placebo or midazolam. For safety outcomes, our validity evaluation showed low risk of bias only in three studies. All studies focused on haemodynamic problems, particularly bradycardia and hypotension. Observed incidences or subsequent interventions never caused concerns. However, only two RCTs allowed meaningful comparisons with control groups. Odds ratios showed no significant difference between the groups, but small sample sizes (50 and 125 patients) must be considered; pooled analyses were not reasonable.

CONCLUSION

All evaluated studies concluded that the use of clonidine in paediatric intensive care units is safe. However, a valid characterisation of the safety profile remains challenging due to limited, biased and heterogeneous data and missing investigation of long-term effects. This evaluation demonstrates the lack of data, which prevents reliable conclusions on the safety of clonidine for long-term sedation in critically ill children. For an evidence-based use, further studies are needed.

Pharmacokinetic and pharmacodynamic considerations of general anesthesia in pediatric subjects

Introduction: The target concentration strategy uses PKPD information for dose determination. Models have also quantified exposure-response relationships, improved understanding of developmental pharmacokinetics, rationalized dose prescription, provided insight into the importance of covariate information, explained drug interactions and driven decision-making and learning during drug development.Areas covered: The prime PKPD consideration is parameter estimation and quantification of variability. The main sources of variability in children are age (maturation) and weight (size). Model use is mostly confined to pharmacokinetics, partly because anesthesia effect models in the young are imprecise. Exploration of PK and PD covariates and their variability hold potential to better individualize treatment.Expert opinion: The ability to model drugs using computer-based technology is hindered because covariate data required to individualize treatment using these programs remain lacking. Target concentration intervention strategies remain incomplete because covariate information that might better predict individualization of dose is absent. Pharmacogenomics appear a valuable area for investigation for pharmacodynamics and pharmacodynamics. Effect measures in the very young are imprecise. Assessment of the analgesic component of anesthesia is crude. While neuromuscular monitoring is satisfactory, depth of anaesthesia EEG interpretation is inadequate. Closed loop anesthesia is possible with better understanding of EEG changes.