Advances in Point-of-Care Ultrasound in Pediatric Acute Care Medicine.

Pediatric point-of-care ultrasonography (POCUS) has grown in utilization and is now an integral part of pediatric acute care. Applications within the pediatric critical care, neonatology and pediatric emergency were once limited to evaluation of undifferentiated shock states, abdominal free fluid assessments in trauma resuscitation and procedural guidance. The body of pediatric POCUS literature is ever expanding and recently published international consensus guidelines are available to guide implementation into clinical practice. The authors present a review of emerging applications and controversies within thoracic, hemodynamic, neurologic, and ocular POCUS in pediatric acute care medicine.

Ultrasound in Cardiopulmonary Arrest and Resuscitation: Constructing Comprehensive Implementation Frameworks in High-Risk Settings.

OBJECTIVES: Information obtained from point-of-care ultrasound during cardiopulmonary arrest and resuscitation (POCUS-CA) can be used to identify underlying pathophysiology and provide life-sustaining interventions. However, integration of POCUS-CA into resuscitation care is inconsistent. We used expert consensus building methodology to help identify discrete barriers to clinical integration. We subsequently applied implementation science frameworks to generate generalizable strategies to overcome these barriers. MEASURES AND MAIN RESULTS: Two multidisciplinary expert working groups used KJ Reverse-Merlin consensus building method to identify and characterize barriers contributing to failed POCUS-CA utilization in a hypothetical future state. Identified barriers were organized into affinity groups. The Center for Implementation Research (CFIR) framework and Expert Recommendations for Implementing Change (CFIR-ERIC) tool were used to identify strategies to guide POCUS-US implementation. RESULTS: Sixteen multidisciplinary resuscitation content experts participated in the working groups and identified individual barriers, consolidated into 19 unique affinity groups that mapped 12 separate CFIR constructs, representing all 5 CFIR domains. The CFIR-ERIC tool identified the following strategies as most impactful to address barriers described in the affinity groups: identify and prepare champions, conduct local needs assessment, conduct local consensus discussions, and conduct educational meetings. CONCLUSIONS: KJ Reverse-Merlin consensus building identified multiple barriers to implementing POCUS-CA. Implementation science methodologies identified and prioritized strategies to overcome barriers and guide POCUS-CA implementation across diverse clinical settings.

Ultrasound assessment of diaphragm thickness, contractility, and strain in healthy pediatric patients.

BACKGROUND: Ultrasound-based diaphragmatic assessments are becoming more common in pediatric acute care, but baseline pediatric diaphragm thickness and contractility values remain unknown. METHODS: We conducted a prospective, observational study of healthy children aged <18 years undergoing elective surgery. Diaphragm thickness at end-expiration (Tdi-exp), thickening fraction (DTF) and excursion were measured by ultrasound during spontaneous breathing and during mechanical ventilation. Diaphragm strain and peak strain rate were ascertained post hoc. Measurements were compared across a priori specified age groups (<1 year, 1 to <3, 3 to <6, 6 to <12, and 12 to <18 years) and with versus without mechanical ventilation. RESULTS: Fifty subjects were evaluated (n = 10 per age group). Baseline mean Tdi-exp was 0.19 ± 0.04 cm, DTF 0.19 ± 0.09, excursion 1.69 ± 0.97 cm, strain -10.3 ± 4.9, peak strain rate -0.48 ± 0.21 s-1 . No significant difference in Tdi-exp or DTF was observed across age groups (p > .05). Diaphragm excursion increased with age (p < .0001). Diaphragm strain was significantly greater in the 12-17-year age group (-14.3 ± 6.4), p = .048, but there were no age-related differences in peak strain rate (p = .08). During mechanical ventilation, there were significant decreases in DTF 0.12 ± 0.04 (p < .0001), excursion 1.08 ± 0.31 cm (p < .0001), strain -4.60 ± 1.93 (p < .0001), and peak strain rate -0.20 ± 0.10 s-1 (p < .0001) while there was no change in Tdi-exp 0.18 ± 0.03 cm (p = .25) when compared to baseline values. CONCLUSION: Pediatric Tdi-exp, DTF, and diaphragm peak strain rate were similar across age groups. Diaphragm excursion and strain varied across age groups. All measures of diaphragm contractility were diminished during mechanical ventilation.

Cardiac Point-of-Care Ultrasound in Pediatric Neurocritical Care: A Case Series.

BACKGROUND: Pediatric brain injury is accompanied by hemodynamic perturbations complicating the optimization of cerebral physiology. Point-of-care ultrasound (POCUS) uses dynamic real-time imaging to complement the physical examination and identify hemodynamic abnormalities in preload, contractility, and afterload conditions, but the contribution of cardiac POCUS in the context of pediatric brain injury is unclear. METHODS: We reviewed cardiac POCUS images integrated in clinical care to examine those with neurological injury and hemodynamic abnormalities. RESULTS: We discuss three children with acute brain injury and myocardial dysfunction identified using cardiac POCUS by bedside clinicians. CONCLUSIONS: Cardiac POCUS may have an important role in caring for children with neurologic injury. These patients received personalized care informed by POCUS data in attempts to stabilize hemodynamics and optimize clinical outcomes.

The association between carotid flow time and fluid responsiveness in children under general anesthesia.

BACKGROUND: Fluid administration in children undergoing surgery requires precision, however, determining fluid responsiveness can be challenging. Ultrasound has been used widely in the emergency department and intensive care units as a noninvasive, bedside manner of determining volume status, but the intraoperative period presents unique challenges as often the chest and abdomen are inaccessible for ultrasound. We investigate whether carotid artery ultrasound, specifically carotid flow time, can be used to determine fluid responsiveness in children under general anesthesia. METHODS: Prospective observational study of 87 children ages 1-12 years who were scheduled for elective noncardiac surgery. Ultrasound of the carotid artery and heart was performed at three time points: (1) after inhalational induction of anesthesia with the subject spontaneously breathing, (2) during positive pressure ventilation through endotracheal tube or supraglottic airway with tidal volume set at 8 ml/kg with PEEP of 10 cmH2 O, and (3) after a 10 ml/kg fluid bolus. Carotid flow time and cardiac output were measured from saved images. RESULTS: Corrected carotid flow time (FTc) increased with initiation of positive pressure ventilation in both fluid responders and nonresponders (352.7 vs. 365.3 msec, p = .005 in fluid responders; 348.3 vs. 365.2 msec, p = .001 in nonresponders). FTc increased after fluid bolus in both responders and nonresponders (365.3 vs. 397.6 msec, p < .001 in fluid responders; 365.2 vs. 397.2 msec, p < .001 in nonresponders). However, baseline FTc during spontaneous ventilation or positive pressure ventilation prior to fluid bolus was not associated with fluid responsiveness. DISCUSSION: Flow time increases with initiation of positive pressure ventilation and after administration of a fluid bolus. FTc may serve as an indicator of fluid status but does not predict fluid responsiveness in children under general anesthesia.

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.

A Call to Action for the Pediatric Critical Care Community.

Healthcare regulatory bodies have escalated concerns regarding the use of point-of-care ultrasound by nonradiology and noncardiology physicians. A recently published PCCMPerspective identified that data do not support many of these concerns and addressed common misconceptions associated with point-of-care ultrasound use in the critical care setting. Indeed, the global point-of-care ultrasound community and specifically the pediatric critical care community have the opportunity to be leaders in demonstrating how to translate new skills and technologies to the bedside in a safe and effective manner. We seek to extend the conversation and propose next steps in supporting integration of point-of-care ultrasound in pediatric critical care practice.

Integrating Focused Cardiac Ultrasound Into Pediatric Septic Shock Assessment.

OBJECTIVES: To assess focused cardiac ultrasound impact on clinician hemodynamic characterization of patients with suspected septic shock as well as expert-generated focused cardiac ultrasound algorithm performance. DESIGN: Retrospective, observational study. SETTING: Single-center, noncardiac PICU. PATIENTS: Less than 18 years old receiving focused cardiac ultrasound study within 72 hours of sepsis pathway initiation from January 2014 to December 2016. INTERVENTIONS: Hemodynamics of patients with suspected septic shock were characterized as fluid responsive, myocardial dysfunction, obstructive physiology, and/or reduced systemic vascular resistance by a bedside clinician before and immediately following focused cardiac ultrasound performance. The clinician's post-focused cardiac ultrasound hemodynamic assessments were compared with an expert-derived focused cardiac ultrasound algorithmic hemodynamic interpretation. Subsequent clinical management was assessed for alignment with focused cardiac ultrasound characterization and association with patient outcomes. MEASUREMENTS AND MAIN RESULTS: Seventy-one patients with suspected septic shock (median, 4.7 yr; interquartile range, 1.6-8.1) received clinician performed focused cardiac ultrasound study within 72 hours of sepsis pathway initiation (median, 2.1 hr; interquartile range, -1.5 to 11.8 hr). Two patients did not have pre-focused cardiac ultrasound and 23 patients did not have post-focused cardiac ultrasound hemodynamic characterization by clinicians resulting in exclusion from related analyses. Post-focused cardiac ultrasound clinician hemodynamic characterization differed from pre-focused cardiac ultrasound characterization in 67% of patients (31/46). There was substantial concordance between clinician's post-focused cardiac ultrasound and algorithm hemodynamic characterization (33/48; κ = 0.66; CI, 0.51-0.80). Fluid responsive (κ = 0.62; CI, 0.40-0.84), obstructive physiology (к = 0.87; CI, 0.64-1.00), and myocardial dysfunction (1.00; CI, 1.00-1.00) demonstrated substantial to perfect concordance. Management within 4 hours of focused cardiac ultrasound aligned with algorithm characterization in 53 of 71 patients (75%). Patients with aligned management were less likely to have a complicated course (14/52, 27%) compared with misaligned management (8/19, 42%; p = 0.25). CONCLUSIONS: Incorporation of focused cardiac ultrasound in the evaluation of patients with suspected septic shock frequently changed a clinician's characterization of hemodynamics. An expert-developed algorithm had substantial concordance with a clinician's post-focused cardiac ultrasound hemodynamic characterization. Management aligned with algorithm characterization may improve outcomes in children with suspected septic shock.

Left Ventricular Diastolic Dysfunction in Pediatric Sepsis: Outcomes in a Single-Center Retrospective Cohort Study.

OBJECTIVES: Left ventricular diastolic dysfunction is associated with difficulty in ventilator weaning and increased mortality in septic adults. We evaluated the association of left ventricular diastolic dysfunction with outcomes in a cohort of children with severe sepsis and septic shock. DESIGN: Retrospective cohort study. SETTING: Single-center noncardiac PICU. PATIENTS: Age greater than 1 month to less than 18 years old with severe sepsis or septic shock from January 2011 to June 2017 with echocardiogram within 48 hours of sepsis onset. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Echocardiograms were retrospectively assessed for mitral inflow E (early) and A (atrial) velocity and e' (early mitral annular motion) septal and lateral velocity. Left ventricular diastolic dysfunction was defined as E/e' greater than 10, E/A less than 0.8, or E/A greater than 1.5. Left ventricular diastolic dysfunction was present in 109 of 204 patients (53%). The data did not demonstrate an association between the presence of left ventricular diastolic dysfunction and the proportion of children requiring invasive mechanical ventilation at the time of echocardiogram (difference in proportion, +5% [72% vs 67%; 95% CI, -8% to 17%]; p = 0.52). The duration of mechanical ventilation was median 192.9 hours (interquartile range, 65.0-378.4 hr) in the left ventricular diastolic dysfunction group versus 151.0 hours (interquartile range, 45.7-244.3 hr) in the group without left ventricular diastolic dysfunction. The presence of left ventricular diastolic dysfunction was not significantly associated with ICU length of stay or mortality. Exploratory analyses revealed that an alternative definition of left ventricular diastolic dysfunction, solely defined by E/e' greater than 10, was found to have an association with mechanical ventilation requirement at the time of echocardiogram (difference in proportion, +15%; 95% CI, 3-28%; p = 0.02) and duration of mechanical ventilation (median, 207.3 vs 146.9 hr). CONCLUSIONS: The data failed to show an association between the presence of left ventricular diastolic dysfunction defined by both E/e' and E/A and the primary and secondary outcomes. When an alternative definition of left ventricular diastolic dysfunction with E/e' alone was used, there was a significant association with respiratory outcomes.

Clinical Signs to Categorize Shock and Target Vasoactive Medications in Warm Versus Cold Pediatric Septic Shock.

OBJECTIVES: Determine level of agreement among clinical signs of shock type, identify which signs clinicians prioritize to determine shock type and select vasoactive medications, and test the association of shock type-vasoactive mismatch with prolonged organ dysfunction or death (complicated course). DESIGN: Retrospective observational study. SETTING: Single large academic PICU. PATIENTS: Patients less than 18 years treated on a critical care sepsis pathway between 2012 and 2016. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Agreement among clinical signs (extremity temperature, capillary refill, pulse strength, pulse pressure, and diastolic blood pressure) was measured using Fleiss and Cohen's κ. Association of clinical signs with shock type and shock type-vasoactive mismatch (e.g., cold shock treated with vasopressor rather than inotrope) with complicated course was determined using multivariable logistic regression. Of 469 patients, clinicians determined 307 (65%) had warm and 162 (35%) had cold shock. Agreement across all clinical signs was low (κ, 0.25; 95% CI, 0.20-0.30), although agreement between extremity temperature, capillary refill, and pulse strength was better than with pulse pressure and diastolic blood pressure. Only extremity temperature (adjusted odds ratio, 26.6; 95% CI, 15.5-45.8), capillary refill (adjusted odds ratio, 15.7; 95% CI, 7.9-31.3), and pulse strength (adjusted odds ratio, 21.3; 95% CI, 8.6-52.7) were associated with clinician-documented shock type. Of the 86 patients initiated on vasoactive medications during the pathway, shock type was discordant from vasoactive medication (κ, 0.14; 95% CI, -0.03 to 0.31) and shock type-vasoactive mismatch was not associated with complicated course (adjusted odds ratio, 0.3; 95% CI, 0.1-1.02). CONCLUSIONS: Agreement was low among common clinical signs used to characterize shock type, with clinicians prioritizing extremity temperature, capillary refill, and pulse strength. Although clinician-assigned shock type was often discordant with vasoactive choice, shock type-vasoactive mismatch was not associated with complicated course. Categorizing shock based on clinical signs should be done cautiously.

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

OBJECTIVES: Diaphragm atrophy is evident during invasive ventilation for pediatric acute respiratory failure, but with unknown significance. We hypothesized that diaphragm atrophy in pediatric acute respiratory failure is associated with prolonged noninvasive positive pressure ventilation following extubation. DESIGN: Prospective observational study. SETTING: Single-center academic PICU. PATIENTS: Invasively ventilated children with acute respiratory failure. INTERVENTIONS: Diaphragm ultrasound was performed within 36 hours after intubation and repeated within 48 hours preceding extubation. Rapid shallow breathing index at 15 and 30 minutes of a spontaneous breathing trial and negative inspiratory force were collected in a subset of patients concurrently with the ultrasound measurements. MEASUREMENTS AND MAIN RESULTS: Diaphragm thickness at end-expiration was measured to assess for diaphragm atrophy during mechanical ventilation. Percentage change in diaphragm thickness at end-expiration was defined as baseline diaphragm thickness at end-expiration minus final, preextubation diaphragm thickness at end-expiration divided by baseline diaphragm thickness at end-expiration. The primary outcome measure was duration of noninvasive positive pressure ventilation following extubation with prolonged use defined as noninvasive positive pressure ventilation use for greater than 24 hours postextubation. Among 56 children, 47 (median age, 15.5 mo; interquartile range, 6-53 mo) had diaphragm thickness at end-expiration measured within 48 hours prior to extubation. Fourteen (30%) had prolonged noninvasive positive pressure ventilation use with median duration 110 hours (interquartile range, 52-130 hr). The median percentage change of diaphragm thickness at end-expiration from baseline among those with and without prolonged noninvasive positive pressure ventilation use was -20% (interquartile range, -32% to -10%) versus -7% (interquartile range, -21% to 0%) (p = 0.04). CONCLUSIONS: Diaphragm atrophy is associated with prolonged postextubation noninvasive positive pressure ventilation in children with acute respiratory failure. Serial bedside diaphragm ultrasound may identify children at risk for prolonged noninvasive positive pressure ventilation use after extubation.

Seeing Is Believing: Ultrasound in Pediatric Procedural Performance.

Point-of-care ultrasound is currently widely used across the landscape of pediatric care. Ultrasound machines are now smaller, are easier to use, and have much improved image quality. They have become common in emergency departments, ICUs, inpatient wards, and outpatient clinics. Recent growth of supportive evidence makes a strong case for using point-of-care ultrasound for pediatric interventions such as vascular access (in particular, central-line placement), lumbar puncture, fluid drainage (paracentesis, thoracentesis, pericardiocentesis), suprapubic aspiration, and soft tissue incision and drainage. Our review of this evidence reveals that point-of-care ultrasound has become a powerful tool for improving procedural success and patient safety. Pediatric patients and clinicians performing procedures stand to benefit greatly from point-of-care ultrasound, because seeing is believing.

Getting to know a familiar face: Current and emerging focused ultrasound applications for the perioperative setting.

Ultrasound technology is available in many pediatric perioperative settings. There is an increasing number of ultrasound applications for anesthesiologists which may enhance clinical performance, procedural safety, and patient outcomes. This review highlights the literature and experience supporting focused ultrasound applications in the pediatric perioperative setting across varied disciplines including anesthesiology. The review also suggests strategies for building educational and infrastructural systems to translate this technology into clinical practice.

Characterization of Thoracic Pathophysiologic Conditions in Patients Receiving High-Frequency Oscillatory Ventilation: Pediatric Experience.

High-frequency oscillatory ventilation (HFOV) is a mode of mechanical ventilation used in severe pediatric respiratory failure. Thoracic ultrasound (US) is a powerful tool for diagnosing acute pathophysiologic conditions during spontaneous respiration and conventional noninvasive and invasive mechanical ventilation. High-frequency oscillatory ventilation differs from conventional modes of ventilation in that it does not primarily use bulk flow delivery for gas exchange but, rather, a number of alternative mechanisms as the result of pressure variations oscillating around a constant distending pressure. Thoracic US has not been well described in patients receiving HFOV, and it is unclear whether the US findings for assessing thoracic pathophysiologic conditions during conventional ventilation are applicable to patients receiving HFOV. We discuss the similarities and differences of thoracic US findings in patients who are spontaneously breathing or receiving conventional ventilation compared to those in patients receiving HFOV.

Progressive Diaphragm Atrophy in Pediatric Acute Respiratory Failure.

OBJECTIVES: Diaphragm atrophy is associated with delayed weaning from mechanical ventilation and increased mortality in critically ill adults. We sought to test for the presence of diaphragm atrophy in children with acute respiratory failure. DESIGN: Prospective, observational study. SETTING: Single-center tertiary noncardiac PICU in a children's hospital. PATIENTS: Invasively ventilated children with acute respiratory failure. MEASUREMENTS AND MAIN RESULTS: Diaphragm thickness at end-expiration and end-inspiration were serially measured by ultrasound in 56 patients (median age, 17 mo; interquartile range, 5.5-52), first within 36 hours of intubation and last preceding extubation. The median duration of mechanical ventilation was 140 hours (interquartile range, 83-201). At initial measurement, thickness at end-expiration was 2.0 mm (interquartile range, 1.8-2.5) and thickness at end-inspiration was 2.5 mm (interquartile range, 2-2.8). The change in thickness at end-expiration during mechanical ventilation between first and last measurement was -13.8% (interquartile range, -27.4% to 0%), with a -3.4% daily atrophy rate (interquartile range, -5.6 to 0%). Thickening fraction = ([thickness at end-inspiration - thickness at end-expiration]/thickness at end-inspiration) throughout the course of mechanical ventilation was linearly correlated with spontaneous breathing fraction (beta coefficient, 9.4; 95% CI, 4.2-14.7; p = 0.001). For children with a period of spontaneous breathing fraction less than 0.5 during mechanical ventilation, those with exposure to a continuous neuromuscular blockade infusion (n = 15) had a significantly larger decrease in thickness at end-expiration compared with children with low spontaneous breathing fraction who were not exposed to a neuromuscular blockade infusion (n = 18) (-16.4%, [interquartile range, -28.4% to -7.0%] vs -7.3%; [interquartile range, -10.9% to -0%]; p = 0.036). CONCLUSIONS: Diaphragm atrophy is present in children on mechanical ventilation for acute respiratory failure. Diaphragm contractility, measured as thickening fraction, is strongly correlated with spontaneous breathing fraction. The combination of exposure to neuromuscular blockade infusion with low overall spontaneous breathing fraction is associated with a greater degree of atrophy.