Diaphragm Atrophy During Pediatric Acute Respiratory Failure Is Associated With Prolonged Noninvasive Ventilation Requirement Following Extubation

What every paediatrician needs to know about mechanical ventilation

Invasive mechanical ventilation (MV) is one of the most practiced interventions in the intensive care unit (ICU) and is unmistakably lifesaving for children with acute respiratory failure (ARF). However, if delivered inappropriately (i.e. ignoring the respiratory system mechanics and not targeted to the need of the individual patient at a specific time point in the disease trajectory), the side effects will outweigh the benefits. Decades of experimental and clinical investigations have resulted in a better understanding of three important detrimental effects of MV. These are ventilation-induced lung injury (VILI), patient self-inflicted lung injury (P-SILI), and ventilation-induced diaphragmatic injury (VIDD). VILI, P-SILI, and VIDD have in common that they occur when there is either too much or too little ventilatory assistance.Conclusion: The purpose of this review is to give the paediatrician an overview of the challenges to prevent these detrimental effects and titrate MV to the individual patient needs.

What's new in pediatric critical care?

Pediatric intensive care medicine is a rapidly evolving field of medicine, with recent publication of landmark papers specific for the pediatric population. Progress has been made in modes of mechanical ventilation, including noninvasive ventilation in pediatric ARDS and after extubation failure, with updated guidelines on ventilator liberation. Improved technology and advancements in hemodynamic support allow for better care of our patients with heart disease. Sepsis burden in children remains high and continued efforts are made to improve survival. A nutritional plan with a tailored approach, focusing on individualized needs, could offer benefits for our patients. Sedation practices and guidelines have been updated, focusing on minimizing delirium and facilitating early mobility. This manuscript highlights some of the most recent advances and updates.

Diaphragm atrophy during invasive mechanical ventilation is related to extubation failure in preterm infants: An ultrasound study

Background

Diaphragm dysfunction is associated with poor outcomes in critically ill patients. Ventilator‐induced diaphragmatic dysfunction (VIDD), including diaphragm atrophy (DA), is poorly studied in newborns. We aimed to assess VIDD and its associations in newborns.

Methods

Single‐center prospective study. Diaphragm thickness was measured at end‐inspiration (TDI) and end‐expiration (TDE) on the right midaxillary line. DA was defined as decrease in TDE ≥ 10%. Daily measurements were recorded in preterm newborns on invasive mechanical ventilation (IMV) for ≥2 days. Clinical characteristics of patients and extubation failure were recorded. Univariate analysis, logistic regression, and mixed models were performed to describe VIDD and associated factors.

Results

We studied 17 patients (median gestational age 270/7 weeks) and 22 IMV cycles (median duration 9 days). Median TDE decreased from 0.118 cm (interquartile range [IQR] 0.094–0.165) on the first IMV day to 0.104 cm (IQR 0.083–0.120) on the last IMV day (p = .092). DA occurred in 11 IMV cycles (50%) from 10 infants early during IMV (median: second IMV day). Mean airway pressure (MAP) and lung ultrasound score (LUS) on the first IMV day were significantly higher in patients who developed DA. DA was more frequent in patients with extubation failure than in those with extubation success within 7 days (83.3 vs. 33.3%, p = .038).

Conclusions

DA, significantly associated with extubation failure, occurred in 58.8% of the study infants on IMV. Higher MAP and LUS at IMV start were associated with DA. Our results suggest a potential role of diaphragm ultrasound to assess DA and predict extubation failure in clinical practice.

POCUS in the PICU: A Narrative Review of Evidence-Based Bedside Ultrasound Techniques Ready for Prime-Time in Pediatric Critical Care

Point-of-care ultrasound (POCUS) is an accessible technology that can identify and treat life-threatening pathology in real time without exposing children to ionizing radiation. We aim to review current evidence supporting the use of POCUS by pediatric intensivists with novice-level experience with bedside ultrasound. Current evidence supports the universal adoption of POCUS-guided internal jugular venous catheter placement and arterial line placement by pediatric critical care physicians. Focused cardiac ultrasound performed by PICU physicians who have completed appropriate training with quality assurance measures in place can identify life-threatening cardiac pathology in most children and important physiological changes in children with septic shock. POCUS of the lungs, pleural space, and diaphragm have great potential to provide valuable information at the bedside after validation of these techniques for use in the PICU with additional research. Based on currently available evidence, a generalizable and attainable POCUS educational platform for pediatric intensivists should include training in vascular access techniques and focused cardiac examination. A POCUS educational program should strive to establish credentialing and quality assurance programs that can be expanded when additional research validates the adoption of additional POCUS techniques by pediatric intensive care physicians.

Association of Extubation Failure Rates With High-Flow Nasal Cannula, Continuous Positive Airway Pressure, and Bilevel Positive Airway Pressure vs Conventional Oxygen Therapy in Infants and Young Children: A Systematic Review and Network Meta-Analysis

Importance

Extubation failure (EF) has been associated with worse outcomes in critically ill children. The relative efficacy of different modes of noninvasive respiratory support (NRS) to prevent EF is unknown.

Objective

To study the reported relative efficacy of different modes of NRS (high-flow nasal cannula [HFNC], continuous positive airway pressure [CPAP], and bilevel positive airway pressure [BiPAP]) compared to conventional oxygen therapy (COT).

Data Sources

MEDLINE, Embase, and CINAHL Complete through May 2022.

Study Selection

Randomized clinical trials that enrolled critically ill children receiving invasive mechanical ventilation for more than 24 hours and compared the efficacy of different modes of postextubation NRS.

Data Extraction and Synthesis

Random-effects models were fit using a bayesian network meta-analysis framework. Between-group comparisons were estimated using odds ratios (ORs) or mean differences with 95% credible intervals (CrIs). Treatment rankings were assessed by rank probabilities and the surface under the cumulative rank curve (SUCRA).

Main Outcomes and Measures

The primary outcome was EF (reintubation within 48 to 72 hours). Secondary outcomes were treatment failure (TF, reintubation plus NRS escalation or crossover to another NRS mode), pediatric intensive care unit (PICU) mortality, PICU and hospital length of stay, abdominal distension, and nasal injury.

Results

A total of 11 615 citations were screened, and 9 randomized clinical trials with a total of 1421 participants were included. Both CPAP and HFNC were found to be more effective than COT in reducing EF and TF (CPAP: OR for EF, 0.43; 95% CrI, 0.17-1.0 and OR for TF 0.27, 95% CrI 0.11-0.57 and HFNC: OR for EF, 0.64; 95% CrI, 0.24-1.0 and OR for TF, 0.34; 95% CrI, 0.16- 0.65). CPAP had the highest likelihood of being the best intervention for both EF (SUCRA, 0.83) and TF (SUCRA, 0.91). Although not statistically significant, BiPAP was likely to be better than COT for preventing both EF and TF. Compared to COT, CPAP and BiPAP were reported as showing a modest increase (approximately 3%) in nasal injury and abdominal distension.

Conclusions and Relevance

The studies included in this systematic review and network meta-analysis found that compared with COT, EF and TF rates were lower with modest increases in abdominal distension and nasal injury. Of the modes evaluated, CPAP was associated with the lowest rates of EF and TF.

The Relationship Between Esophageal Pressure and Diaphragm Thickening Fraction in Spontaneously Breathing Sedated Children: A Feasibility Study

OBJECTIVES

Diaphragm ultrasound is a novel alternative to esophageal pressure measurements in the evaluation of diaphragm function and activity, but data about its reliability in a pediatric setting are lacking. We aimed to compare the esophageal pressure swing (∆Pes, gold standard) with the diaphragmatic thickening fraction (DTF) as a measure of inspiratory effort in sedated children. Additionally, we studied the effect of positive end-expiratory pressure (PEEP) on the end-expiratory thickness of the diaphragm (DTee).

DESIGN

Prospective open-label non-randomized interventional physiological cohort study.

SETTING

Operating room in tertiary academic hospital.

PATIENTS

Children 28 days to 13 years old scheduled for elective surgery with general anesthesia, spontaneously breathing through a laryngeal mask airway, were eligible for inclusion. Exclusion criteria were disorders or previous surgery of the diaphragm, anticipated difficult airway or acute cardiopulmonary disease. All measurements were performed prior to surgery.

INTERVENTIONS

Patients were subjected to different levels of respiratory load, PEEP and anesthetic depth in a total of seven respiratory conditions.

MEASUREMENTS AND MAIN RESULTS

The esophageal pressure and diaphragm thickening fraction were simultaneously recorded for five breaths at each respiratory condition. The relation between ∆Pes and DTF was studied in a mixed model. We analyzed 407 breaths in 13 patients. Both DTF (p = 0.03) and ∆Pes (p = 0.002) could detect respiratory activity, and ∆Pes and DTF were associated across respiratory conditions (p < 0.001; R2 = 31%). With increasing inspiratory load, ∆Pes increased significantly, while DTF did not (p = 0.08). Additionally, DTee did not differ significantly between 10, 5, and 0 cm H2O PEEP (p = 0.08).

CONCLUSIONS

In spontaneously breathing sedated children and across different respiratory conditions, DTF could differentiate minimal or no inspiratory effort from substantial inspiratory effort and was associated with ∆Pes. Increased efforts resulted in higher ∆Pes but not larger DTF.

Contemporary Use of Ultrasonography in Acute Care Pediatrics

Use of ultrasonography by clinicians at the point of care has expanded widely and rapidly. Pediatric acute care providers now leverage this valuable tool to guide procedures, diagnose pathophysiologic processes, and inform time-sensitive decisions in sick and unstable children. However, the deployment of any new technology must be packaged with training, protocols, and safeguards to optimize safety for patients, providers, and institutions. As ultrasonography is increasingly incorporated into residency, fellowship, and even medical student curricula, it is important that educators and trainees are aware of the diversity of its clinical applications. This article aims to review the current state of point-of-care ultrasonography in acute care pediatrics, with an emphasis on the literature supporting the use of this important clinical tool.

No association between thickening fraction of the diaphragm and extubation success in ventilated children

Introduction

In mechanically ventilated adults, thickening fraction of diaphragm (dTF) measured by ultrasound is used to predict extubation success. Whether dTF can also predict extubation success in children is unclear.

Aim

To investigate the association between dTF and extubation success in children. Second, to assess diaphragm thickness during ventilation and the correlation between dTF, diaphragm thickness (Tdi), age and body surface.

Method

Prospective observational cohort study in children aged 0-18 years old with expected invasive ventilation for >48 h. Ultrasound was performed on day 1 after intubation (baseline), day 4, day 7, day 10, at pre-extubation, and within 24 h after extubation. Primary outcome was the association between dTF pre-extubation and extubation success. Secondary outcome measures were Tdi end-inspiratory and Tdi end-expiratory and atrophy defined as <10% decrease of Tdi end-expiratory versus baseline at pre-extubation. Correlations were calculated with Spearman correlation coefficients. Inter-rater reliability was calculated with intraclass correlation (ICC).

Results

Fifty-three patients, with median age 3.0 months (IQR 0.1-66.0) and median duration of invasive ventilation of 114.0 h (IQR 55.5-193.5), were enrolled. Median dTF before extubation with Pressure Support 10 above 5 cmH₂O was 15.2% (IQR 9.7-19.3). Extubation failure occurred in six children, three of whom were re-intubated and three then received non-invasive ventilation. There was no significant association between dTF and extubation success; OR 0.33 (95% CI; 0.06-1.86). Diaphragmatic atrophy was observed in 17/53 cases, in three of extubation failure occurred. Children in the extubation failure group were younger: 2.0 months (IQR 0.81-183.0) vs. 3.0 months (IQR 0.10-48.0); p = 0.045. At baseline, pre-extubation and post-extubation there was no significant correlation between age and BSA on the one hand and dTF, Tdi- insp and Tdi-exp on the other hand. The ICC representing the level of inter-rater reliability between the two examiners performing the ultrasounds was 0.994 (95% CI 0.970-0.999). The ICC of the inter-rater reliability between the raters in 36 paired assessments was 0.983 (95% CI 0.974-0.990).

Conclusion

There was no significant association between thickening fraction of the diaphragm and extubation success in ventilated children.

Diaphragmatic Thickening Fraction by Ultrasound in Mechanically Ventilated Pediatric Patients: Pilot Observations During Spontaneous Breathing Trials

OBJECTIVES

In critically ill, mechanically ventilated adults, diaphragmatic atrophy and reduced diaphragmatic thickening fraction (DTF) has been associated with poor extubation outcomes. Diaphragmatic ultrasound assessment in critically ill pediatric patients shows similar results, though studies are on-going. We sought to explore the feasibility and utility of using DTF, obtained during a spontaneous breathing trial (SBT) in predicting weaning outcomes.

METHODS

We conducted a prospective, observational study in a single-center tertiary noncardiac pediatric intensive care unit (PICU) in a children's hospital. Mechanically ventilated pediatric patients were included except for those with preexisting conditions of neuromuscular weakness, diaphragm paresis, or chronic respiratory failure requiring non-invasive or invasive mechanical ventilation at baseline. A convenience sample of 38 patients were included in the study.

RESULTS

Weaning failure occurred in 10/38 (26%) instances with 9/38 (24%) occurring due to failed SBT and 1/38 (2%) due to failed extubation requiring reintubation. Median DTF was 24% (IQR: 12-33). DTF was significantly lower in instances of failed SBT, 12% compared to 27% (P < .01). The odds ratio (OR) of SBT failure utilizing: TF < 25% is 12 (CI: 1.33-108.0, Z-score: 2.22, P = .027), TV <5 mL/kg was 10.4 (CI: 1.76-61.67, Z-score: 2.58, P = .01), and combined TV <5 mL/kg and TF < 25% is 17.6 (CI: 1.19-259.61, Z-score: 2.09, P = .04).

CONCLUSIONS

Our preliminary study suggests that ultrasound measurements of diaphragm thickening fraction during spontaneous breaths in mechanically ventilated pediatric patients may be a useful addition in predicting weaning readiness.

Commentary on High-Flow Nasal Cannula and Continuous Positive Airway Pressure Practices After the First-Line Support for Assistance in Breathing in Children Trials

Continuous positive airway pressure (CPAP) and heated humidified high-flow nasal cannula (HFNC) are commonly used to treat children admitted to the PICU who require more respiratory support than simple oxygen therapy. Much has been published on these two treatment modalities over the past decade, both in Pediatric Critical Care Medicine (PCCM ) and elsewhere. The majority of these studies are observational analyses of clinical, administrative, or quality improvement datasets and, therefore, are only able to establish associations between exposure to treatment and outcomes, not causation. None of the initial randomized clinical trials comparing HFNC and CPAP were definitive due to their relatively small sample sizes with insufficient power for meaningful clinical outcomes (e.g., escalation to bilevel noninvasive ventilation or intubation, duration of PICU-level respiratory support, mortality) and often yielded ambiguous findings or conflicting results. The recent publication of the First-Line Support for Assistance in Breathing in Children (FIRST-ABC) trials represented a major step toward understanding the role of CPAP and HFNC use in critically ill children. These large, pragmatic, randomized clinical trials examined the efficacy of CPAP and HFNC either for "step up" (i.e., escalation in respiratory support) during acute respiratory deterioration or for "step down" (i.e., postextubation need for respiratory support) management. This narrative review examines the body of evidence on HFNC published in PCCM , contextualizes the findings of randomized clinical trials of CPAP and HFNC up to and including the FIRST-ABC trials, provides guidance to PICU clinicians on how to implement the literature in current practice, and discusses remaining knowledge gaps and future research priorities.

Diagnostic Utility of Point-of-Care Ultrasound in the Pediatric Cardiac Intensive Care Unit

Purpose of Review

Recent Findings

Summary

Supplementary Information

Factores clínicos asociados a extubación fallida y a estridor laríngeo post-extubación en pacientes adultos con ventilación mecánica invasiva

Introducción. La intubación orotraqueal es un procedimiento que conlleva riesgos como la extubación fallida y el estridor laríngeo, los cuales aumentan el riesgo de morbilidad. Objetivo. Identificar los factores asociados a extubación fallida temprana (≤24 horas) y al desarrollo de estridor laríngeo post-extubación en pacientes adultos con ventilación mecánica invasiva (VMI). Materiales y métodos. Estudio de casos y controles con recolección prospectiva de información realizado en la unidad de cuidados intensivos (UCI) de un hospital de IV nivel de Bogotá, Colombia, entre abril de 2019 y febrero de 2020. Se incluyeron 180 pacientes con VMI ≥24 horas y al menos ≥1 intento de extubación: 30 casos, definidos como pacientes con extubación fallida temprana (≤24 horas a la extubación) y 150 controles. Las diferencias en las variables consideradas entre casos y controles se determinaron mediante las pruebas t de Student y Chi 2 o exacta de Fisher. Además, se realizó un análisis multivariado (modelo de regresión logística no condicional) para determinar los factores asociados con extubación fallida y estridor laríngeo post-extubación, calculando los Odds ratio (OR) con sus respectivos intervalos de confianza al 95% (IC95%). Se consideró un nivel de significancia de p<0.05. Resultados. La extubación fallida temprana y el estridor laríngeo tuvieron una prevalencia de 16.66% (n=30) y 3.89% (n=7), respectivamente. En el análisis multivariado, el antecedente de intubación (OR=4.27, IC95%=1.44-12.66), la presencia de cáncer activo (OR= 2.92, IC95%=1.08-7.90) y ser diagnosticado con neumonía (OR=2.84, IC95%=1.15-6.99) se asociaron significativamente con extubación fallida, mientras que la duración de la VMI (OR=1.53, IC95%=1.18-1.99) y el antecedente de intubación (OR=37.9, IC95%=2.22-650.8), con estridor laríngeo post-extubación. Conclusiones. Con base en los resultados aquí obtenidos, se sugiere considerar factores como antecedente de intubación previa, comorbilidad con cáncer y diagnóstico de neumonía en la estratificación de estos pacientes críticos para aumentar la probabilidad de una extubación exitosa.

Early Restrictive Fluid Strategy Impairs the Diaphragm Force in Lambs with Acute Respiratory Distress Syndrome

BACKGROUND

The effect of fluid management strategies in critical illness-associated diaphragm weakness are unknown. This study hypothesized that a liberal fluid strategy induces diaphragm muscle fiber edema, leading to reduction in diaphragmatic force generation in the early phase of experimental pediatric acute respiratory distress syndrome in lambs.

METHODS

Nineteen mechanically ventilated female lambs (2 to 6 weeks old) with experimental pediatric acute respiratory distress syndrome were randomized to either a strict restrictive fluid strategy with norepinephrine or a liberal fluid strategy. The fluid strategies were maintained throughout a 6-h period of mechanical ventilation. Transdiaphragmatic pressure was measured under different levels of positive end-expiratory pressure (between 5 and 20 cm H2O). Furthermore, diaphragmatic microcirculation, histology, inflammation, and oxidative stress were studied.

RESULTS

Transdiaphragmatic pressures decreased more in the restrictive group (-9.6 cm H2O [95% CI, -14.4 to -4.8]) compared to the liberal group (-0.8 cm H2O [95% CI, -5.8 to 4.3]) during the application of 5 cm H2O positive end-expiratory pressure (P = 0.016) and during the application of 10 cm H2O positive end-expiratory pressure (-10.3 cm H2O [95% CI, -15.2 to -5.4] vs. -2.8 cm H2O [95% CI, -8.0 to 2.3]; P = 0.041). In addition, diaphragmatic microvessel density was decreased in the restrictive group compared to the liberal group (34.0 crossings [25th to 75th percentile, 22.0 to 42.0] vs. 46.0 [25th to 75th percentile, 43.5 to 54.0]; P = 0.015). The application of positive end-expiratory pressure itself decreased the diaphragmatic force generation in a dose-related way; increasing positive end-expiratory pressure from 5 to 20 cm H2O reduced transdiaphragmatic pressures with 27.3% (17.3 cm H2O [95% CI, 14.0 to 20.5] at positive end-expiratory pressure 5 cm H2O vs. 12.6 cm H2O [95% CI, 9.2 to 15.9] at positive end-expiratory pressure 20 cm H2O; P < 0.0001). The diaphragmatic histology, markers for inflammation, and oxidative stress were similar between the groups.

CONCLUSIONS

Early fluid restriction decreases the force-generating capacity of the diaphragm and diaphragmatic microcirculation in the acute phase of pediatric acute respiratory distress syndrome. In addition, the application of positive end-expiratory pressure decreases the force-generating capacity of the diaphragm in a dose-related way. These observations provide new insights into the mechanisms of critical illness-associated diaphragm weakness.

EDITOR’S PERSPECTIVE

Point-of-Care Ultrasound in the Pediatric Intensive Care Unit

Ultrasonography has been widely used in medicine for decades but often by specific users such as cardiologists, obstetricians, and radiologists. In the last several years, the use of this imaging modality has moved to the bedside, with clinicians performing and interpreting focused point of care ultrasonography to aid in immediate assessment and management of their patients. The growth of point of care ultrasonography has been facilitated by advancement in ultrasound-related technology and emerging studies and protocols demonstrating its utility in clinical practice. However, considerable challenges remain before this modality can be adopted across the spectrum of disciplines, primarily as it relates to training, competency, and standardization of usage. This review outlines the history, current state, challenges and the future direction of point of care ultrasonography specifically in the field of pediatric critical care medicine.

Characteristics and Risk Factors of Children Requiring Prolonged Mechanical Ventilation vs. Non-prolonged Mechanical Ventilation in the PICU: A Prospective Single-Center Study

BACKGROUND

Prolonged mechanical ventilation (PMV) has become an enormous challenge in intensive care units (ICUs) around the world. Patients treated with PMV are generally in poor health. These patients represent a select cohort with significant morbidity, mortality, and resource utilization. The status of children who have undergone PMV in China is unknown. Our goal is to investigate the prevalence and characteristics of pediatric patients with PMV, as well as the risk factors of PMV in the pediatric intensive care unit (PICU).

METHODS

The subjects were divided into two groups. The PMV group(MV ≥ 14 days) and the non-PMV group(2 days < MV <14 days). The baseline characteristics, treatments, mortality and other results between the two groups were compared. The risk factors associated with PMV were evaluated using univariate and multivariable analyses.

RESULTS

Of the 382 children enrolled, 127 (33.2%) received prolonged mechanical ventilation. The most common cause of MV in the PMV group was acute lung disease (48.0%), followed by acute circulatory system disease (26.0%), acute neurological disease (15.0%), postoperative monitoring (10.2%), and others (0.8%). Comorbidities were more prevalent among the PMV group (P = 0.004). The patients with PMV had a higher rate of premature birth (24.4 vs. 14.1%, P = 0.013) and higher PIM3 score at admission [5.6(3.0-9.9) vs. 4.1(1.7-5.5), P < 0.001]. The use of inotropes/vasopressors (63.8 vs. 43.1%, P < 0.001) was more common in patients with PMV compared with those in the non-PMV group. In the PMV group, the rate of extubation failure (39.4 vs. 6.7%, P < 0.001) was higher than the non-PMV group. The median hospital stay [35(23.0-50.0)d vs. 20(14.0-31.0)d, P < 0.001], PICU stay [22(15.0-33.0)d vs. 9(6.0-12.0)d, P < 0.001], hospitalization costs [¥391,925(263,259-614,471) vs. ¥239,497(158,723-350,620), P < 0.001], and mortality after 1-month discharge (22.0 vs. 1.6%, P < 0.001) were higher in the PMV group. Multivariate analysis revealed that age <1 year old, a higher PIM3 score at admission, prematurity, the use of inotropes or vasopressors, extubation failure, and ventilator mode on the first day of MV were associated with PMV.

CONCLUSIONS

The incidence and mortality of PMV in pediatric patients is surprisingly high. Premature infants or patients with severe disease or extubation failure are at higher risk of PMV. Patients with PMV exhibit a greater burden with regard to medical costs than those on non-PMV. It is important to establish specialized weaning units for mechanically ventilated patients with stable conditions.

A narrative review of diaphragmatic ultrasound in pediatric critical care

The use of point of care ultrasound (POCUS) at the bedside has increased dramatically within emergency medicine and in critical care. Applications of POCUS have spread to include diaphragmatic assessments in both adults and children. Diaphragm POCUS can be used to assess for diaphragm dysfunction (DD) and atrophy or to guide ventilator titration and weaning. Quantitative, semi-quantitative and qualitative measurements of diaphragm thickness, diaphragm excursion, and diaphragm thickening fraction provide objective data related to DD and atrophy. The potential for quick, noninvasive, and repeatable bedside diaphragm assessments has led to a growing amount of literature on diaphragm POCUS. To date, there are no reviews of the current state of diaphragm POCUS in pediatric critical care. The aims of this narrative review are to summarize the current literature regarding techniques, reference values, applications, and future innovations of diaphragm POCUS in critically ill children. A summary of current practice and future directions will be discussed.