Point-of-care lung ultrasound on admission to the PICU to determine the cause of respiratory failure.

A point-of-care lung ultrasound exam will be performed on admission (no later than 14 hours following admission, allowing for participant stabilization and care) to the PICU and within 6 hours of any escalation in mechanical ventilatory support without interrupting clinical care, by study investigators blinded to participant history, physical examination, and diagnostic testing/imaging and who are not involved in the clinical management of the participant. Investigators will use a six-zone standardized scanning protocol with pattern analysis to form a diagnosis for the cause of the participant's respiratory failure. Images will be acquired by pediatric critical care trainees and saved online; accuracy of diagnoses based on the ultrasound exam will be evaluated by a expert sonographer offline.

The sensitivity of the lung ultrasound in identifying the etiology of acute pediatric respiratory failure will be determined by comparison with the final criterion or "gold standard" diagnosis generated by a blinded review of the chart after discharge by a study investigator blinded to the case. The hypothesis is that the lung ultrasound performed on admission to the PICU will have a sensitivity of > 90% in determining the etiology of acute respiratory failure in children (as determined by an independent review of the participant's medical record following hospital discharge).

The specificity of the lung ultrasound in identifying the etiology of acute pediatric respiratory failure will be determined by comparison with the final criterion or "gold standard" diagnosis generated by a blinded review of the chart after discharge by a study investigator blinded to the case. The hypothesis is that the lung ultrasound performed on admission to the PICU will have a specificity of > 90% in determining the etiology of acute respiratory failure in children (as determined by an independent review of the participant's medical record following hospital discharge).

Ultrasound images obtained by a critical care trainee will be saved online for review by an expert sonographer. The expert sonographer will overread the images; findings will be compared at all ultrasound points to determine percent agreement in interpreting ultrasound exam findings between the trainee and expert sonographer. Additionally final ultrasonographic diagnosis will be compared between trainee and expert sonographers. Interpretation of exam findings and determination of exam diagnosis will be compared to determine the inter-observer reliability of point-of-care lung ultrasound exams in acute pediatric respiratory failure. The hypothesis is that the inter-observer reliability between trainee and expert sonographers for point-of-care lung ultrasound findings will be >80%.

Chest x-rays findings (as determine by board certified pediatric radiologists) obtained during the course of routine clinical care will be compared to point-of-care lung ultrasound examinations when completed within 6 hours of each other. The hypothesis is that lung ultrasound will have a higher rate of detection of when compared with a chest radiograph taken less than 6 hours prior to or less than 6 hours after lung ultrasound examination.