A Network Meta-analysis of Dexamethasone for Preventing Postextubation Upper Airway Obstruction in Children

Getting the dose right using physiologically-based pharmacokinetic modeling: dexamethasone to prevent post-extubation stridor in children as proof of concept

Introduction

Critically ill patients show large variability in drug disposition due to e.g., age, size, disease and treatment modalities. Physiologically-based pharmacokinetic (PBPK) models can be used to design individualized dosing regimens taking this into account. Dexamethasone, prescribed for the prevention post-extubation stridor (PES), is metabolized by the drug metabolizing enzyme CYP3A. As CYP3A4 undergoes major changes during childhood, we aimed to develop age-appropriate dosing recommendations for children of dexamethasone for PES, as proof of concept for PBPK modeling to individualize dosing for critically ill patients.

Methods

All simulations were conducted in Simcyp™ v21 (a population-based PBPK modeling platform), using an available dexamethasone compound model and pediatric population model in which CYP3A4 ontogeny is incorporated. Published pharmacokinetic (PK) data was used for model verification. Evidence for the dose to prevent post-extubation stridor was strongest for 2-6 year old children, hence simulated drug concentrations resulting from this dose from this age group were targeted when simulating age-appropriate doses for the whole pediatric age range.

Results

Dexamethasone plasma concentrations upon single and multiple intravenous administration were predicted adequately across the pediatric age range. Exposure-matched predictions of dexamethasone PK indicated that doses (in mg/kg) for the 2-6 years olds can be applied in 3 month-2 year old children, whereas lower doses are needed in children of other age groups (60% lower for 0-2 weeks, 40% lower for 2-4 weeks, 20% lower for 1-3 months, 20% lower for 6-12 year olds, 40% lower for 12-18 years olds).

Discussion

We show that PBPK modeling is a valuable tool that can be used to develop model-informed recommendations using dexamethasone to prevent PES in children. Based on exposure matching, the dose of dexamethasone should be reduced compared to commonly used doses, in infants <3 months and children ≥6 years, reflecting age-related variation in drug disposition. PBPK modeling is an promising tool to optimize dosing of critically ill patients.

Implementing the Pediatric Ventilator Liberation Guidelines Using the Most Current Evidence

Invasive mechanical ventilation is prevalent and associated with considerable morbidity. Pediatric critical care teams must identify the best timing and approach to liberating (extubating) children from this supportive care modality. Unsurprisingly, practice variation varies widely. As a first step to minimizing that variation, the first evidence-based pediatric ventilator liberation guidelines were published in 2023 and included 15 recommendations. Unfortunately, there is often a substantial delay before clinical guidelines reach widespread clinical practice. As such, it is important to consider barriers and facilitators using a systematic approach during implementation planning and design. In this narrative review, we will (1) summarize guideline recommendations, (2) discuss recent evidence and identify practice gaps relating to those recommendations, and (3) hypothesize about potential barriers and facilitators to their implementation in clinical practice.

Framework for Research Gaps in Pediatric Ventilator Liberation

BACKGROUND

The 2023 International Pediatric Ventilator Liberation Clinical Practice Guidelines provided evidence-based recommendations to guide pediatric critical care providers on how to perform daily aspects of ventilator liberation. However, because of the lack of high-quality pediatric studies, most recommendations were conditional based on very low to low certainty of evidence.

RESEARCH QUESTION

What are the research gaps related to pediatric ventilator liberation that can be studied to strengthen the evidence for future updates of the guidelines?

STUDY DESIGN AND METHODS

We conducted systematic reviews of the literature in eight predefined Population, Intervention, Comparator, Outcome (PICO) areas related to pediatric ventilator liberation to generate recommendations. Subgroups responsible for each PICO question subsequently identified major research gaps by synthesizing the literature. These gaps were presented at an international symposium at the Pediatric Acute Lung Injury and Sepsis Investigators meeting in spring 2022 for open discussion. Feedback was incorporated, and final evaluation of research gaps are summarized herein. Although randomized controlled trials (RCTs) represent the highest level of evidence, the panel sought to highlight areas where alternative study designs also may be appropriate, given challenges with conducting large multicenter RCTs in children.

RESULTS

Significant research gaps were identified in six broad areas related to pediatric ventilator liberation. Several of these areas necessitate multicenter RCTs to provide definitive results, whereas other gaps can be addressed with multicenter observational studies or quality improvement initiatives. Furthermore, a need for some physiologic studies in several areas remains, particularly regarding newer diagnostic methods to improve identification of patients at high risk of extubation failure.

INTERPRETATION

Although pediatric ventilator liberation guidelines have been created, the certainty of evidence remains low and multiple research gaps exist that should be bridged through high-quality RCTs, multicenter observational studies, and quality improvement initiatives.

Predictors and outcomes of extubation failures in a pediatric intensive care unit: A retrospective study

Objectives

This study was aimed at determining the extubation failure (EF) rate in a pediatric intensive care unit (PICU), and assessing the etiology, associated risk factors, and outcomes.

Methods

We conducted a retrospective study on 335 pediatric patients admitted to King Abdulaziz University Hospital between 2018 and 2020, ranging in age from 1 month to 14 years, who required invasive mechanical ventilation (MV) for >24 h. Extubation readiness was determined by the attending pediatric intensive care physician, according to the patients' clinical status and extubation readiness criteria.

Results

In the cohort of 335 patients, 42 experienced issues during extubation (failure rate, 12.5%). Cardiovascular disease (42.9%) was the main primary admission condition in patients with EF. Younger age (median, interquartile range [IQR]: 4, 1.38-36 months) was strongly associated with EF compared with successful extubation (median, IQR: 12, 2-48; p = 0.036), and with a high predicted mortality rate (10.9%; p < 0.001) and Pediatric Risk of Mortality III (PRISM) score (13; p < 0.001). Furthermore, prolonged ICU stay (25.5 days; p < 0.001) and longer MV requirements (4 days; p < 0.001) before extubation in patients with EF were associated with a high mortality rate (∼12%; p < 0.001). Interestingly, dexamethasone administration before extubation significantly alleviated EF risk (28.3%; p < 0.001).

Conclusion

A higher EF rate in younger patients may potentially be associated with longer ICU stays, prolonged MV requirements before extubation, and the primary diagnostic condition. Dexamethasone effectively alleviated EF incidence. Further research with a rigorous evidence-based study design is necessary to substantiate the factors identified as predictors of EF and to develop strategies to avoid EF.

Pre-Extubation Ultrasound Measurement of In Situ Cuffed Endotracheal Tube Laryngeal Air Column Width Difference: Single-Center Pilot Study of Relationship With Post-Extubation Stridor in Subjects Younger Than 5 Years Old

OBJECTIVES

Post-extubation stridor (PES) is difficult to predict before extubation. We therefore evaluated the potential diagnostic performance of pre-extubation laryngeal air column width difference (LACWD) measurement, as assessed by intensivist-performed point-of-care laryngeal ultrasound, in relation to clinically important PES.

DESIGN

Prospective observational cohort study.

SETTING

Single quaternary care PICU (July 19, 2021, to October 31, 2022).

PATIENTS

Included subjects were younger than 5 years old, intubated with a cuffed endotracheal tube, requiring invasive mechanical ventilation for greater than 24 hours, and nearing extubation. Subjects at high risk for supraglottic airway obstruction were excluded.

INTERVENTIONS

Laryngeal ultrasound with measurement of laryngeal air column width with the endotracheal tube cuff inflated and deflated. Clinically important PES was defined as a high-pitched inspiratory respiratory noise suspected to be from a subglottic focus necessitating received medical intervention or reintubation.

MEASUREMENTS AND MAIN RESULTS

Among 53 enrolled subjects, 18 of 53 (34%) experienced PES and three of 53 (6%) were reintubated because of severe subglottic upper airway obstruction. Median LACWD was significantly lower in the stridor group compared with the nonstridor group (∆ 0.41 mm; 95% CI, 0.37-0.48; p < 0.001). The area under the receiver operating characteristic curve for LACWD as a diagnosis of PES was 0.94 (95% CI, 0.89-1.00; p < 0.001). The LACWD cutoff for PES was less than or equal to 0.47 mm, which yielded a diagnostic sensitivity of 91.4% and specificity of 88.9%. In this population, the pre-to-post-test change in probability of PES for LACWD less than or equal to 0.47 mm is 0.34 to 0.81.

CONCLUSIONS

Pre-extubation LACWD is a novel, noninvasive assessment that can be performed and interpreted by the intensivist at the bedside. There is, however, diagnostic uncertainty in the use of this measurement for identifying those at-risk of PES and larger validation studies are needed.

Pediatric Ventilator Liberation: One-Hour Versus Two-Hour Spontaneous Breathing Trials in a Single Center

BACKGROUND

The optimal spontaneous breathing trial (SBT) duration is not known for children who are critically ill. The study objective was to evaluate extubation outcomes between cohorts exposed to a 1- or 2-h SBT.

METHODS

This was a retrospective cohort study of a quality improvement project database in a 24-bed pediatric ICU. The intervention was a respiratory therapist-driven SBT clinical pathway across 2 improvement cycles by using a 2- or 1-h SBT. The primary outcomes were extubation failure and rescue noninvasive ventilation in the first 48 h. Secondary outcomes included SBT results and process measures.

RESULTS

There were 218 and 305 encounters in the 2- and 1-h cohorts, respectively. Extubation failure (7.3 vs 8.5%; P = .62) and rescue noninvasive ventilation rates (9.3 vs 8.2%; P = .68) were similar. In logistic regression models, SBT duration was not independently associated with either primary outcome. Extubation after 1-h SBT failure was associated with significantly higher odds of rescue noninvasive ventilation exposure (odds ratio 3.94, 95% CI 1.3-11.9; P = .02). SBT results were not associated with odds of extubation failure. There were 1,072 (2 h) and 1,333 (1 h) SBTs performed. The 1-h SBT pass rate was significantly higher versus the 2-h SBT (71.4 vs 51.1%; P < .001). Among all failed SBTs, the top 3 reported failure modes were tidal volume ≤ 5 mL/kg (23.6%), breathing frequency increase > 30% (21%), and oxygen saturation < 92% (17.3%). When considering all failed SBTs, 75.5% of failures occurred before 45 min.

CONCLUSIONS

A 1-h SBT may be a viable alternative to a 2-h version for the average child who is critically ill. Further, a 1-h SBT may better balance extubation outcomes and duration of invasive ventilation for the general pediatric ICU population.