Introducción. La bronquiolitis aguda (BA) es una enfermedad inflamatoria de los bronquiolos que supone una gran carga asistencial anual en Pediatría. Las pausas de apnea, la hipercapnia por fatiga y la hipoxemia por la formación de atelectasias son las causas más frecuentes de necesidad de ingreso en UCIP para soporte respiratorio avanzado. La oxigenoterapia de alto flujo (OAF) y la ventilación no invasiva (VNI) mejoran los flujos inspiratorio y espiratorio, consiguiendo disminuir el esfuerzo respiratorio, el colapso dinámico de la vía aérea, y una mejoría del intercambio gaseoso, en muchos casos evitando la ventilación mecánica (VM). La ecografía clínica, llevada a cabo por los profesionales directamente encargados del cuidado de los pacientes, ha supuesto un gran avance en la práctica clínica, que aporta una información anatómica y/o fisiológica que integrar a los datos clínicos y de laboratorio, para la toma de decisiones terapéuticas y la monitorización de la respuesta. La ecografía pulmonar clínica (EP-PC) es una de las modalidades que más posibilidades ofrece. La EP-PC parece tener cierta correlación con la gravedad clínica de las BA, y capacidad predictiva de la necesidad y duración de hospitalización, oxigenoterapia y soporte respiratorio distinto del oxígeno convencional, aunque no hay estudios suficientes que incluyan pacientes graves en UCIP.
Objetivos. No está comprobado que la mejoría de la función respiratoria que experimentan los niños con BA moderadas y graves sometidos a soporte respiratorio no invasivo en la UCIP sea debido a una mejoría de la aireación pulmonar, ni que patrones de mayor pérdida de aireación pulmonar supongan una mayor gravedad clínica. Los objetivos de este estudio son cuantificar la aireación pulmonar mediante ecografía de las BA moderadas y graves, analizar la asociación entre el score ecográfico de aireación pulmonar con la escala de gravedad clínica y con la evolución clínica, valorar la capacidad predictiva del score ecográfico de aireación pulmonar con la necesidad de VM, y estudiar la concordancia inter-observador en cuanto a los hallazgos ecográficos.
Métodos. Estudio prospectivo observacional que incluyó 36 niños < 2 años con diagnóstico de BA, que precisaron soporte respiratorio con OAF o VNI. Se realizó una primera valoración clínica y ecográfica al ingreso en UCIP, y una segunda valoración tras 2-3 horas de haber iniciado el soporte respiratorio no invasivo. Se obtuvo un score de aireación pulmonar cuantitativo que poder comparar.
Resultados y conclusiones. No pudimos demostrar que la aireación pulmonar cuantificada mediante el score ecográfico de aireación pulmonar tuviera correlación alguna con la puntuación de la escala clínica de gravedad, pero si encontramos relación con la evolución clínica posterior en cuanto a duración del ingreso en UCIP y duración de hospitalización total. Tampoco encontramos capacidad predictiva del score ecográfico de aireación pulmonar con la necesidad ni duración de VM. Los hallazgos ecográficos de las BA son múltiples pero inespecíficos, por lo que la EP-PC debe ser considerada como una extensión de la evaluación clínica. La concordancia inter-observador fue buena, mejor para los patrones extremos que para los patrones intermedios de pérdida de aireación.
Acute bronchiolitis is a very common lung infection in young children and infants. It is an acute inflammatory injury of the bronchioles caused by a viral infection, usually the respiratory syncytial virus, and represents a large annual health care burden in both outpatient and inpatient settings. Only a small proportion of children require admission to the Pediatric Intensive Care Unit, particularly young infants and those with risk factors, due to respiratory failure or disease´s complications. Apnea and hypercapnic respiratory failure due to muscular fatigue are the most frequent reasons for admission to PICU, although hypoxemia caused by development of atelectasis may also require advanced respiratory support. Acute bronchiolitis usually presents with a mixed pattern of restrictive disease with areas of loss of aeration and intrapulmonary shunt, and an obstructive pattern of air trapping and overdistention, being a challenge its clinical management. Diagnosis of acute bronchiolitis is based on typical history and results of a physical examination, and its treatment is focused on supportive care. Non-invasive respiratory support (high-flow oxygen therapy and non-invasive ventilation with continuous positive airway pressure or two pressure levels) provides heated and humidified oxygen and improves inspiratory and expiratory flows, reducing respiratory effort, dynamic airway collapse, and improving gas exchange, in many cases avoiding the need for intubation and mechanical ventilation.
Point-of-care ultrasound, ultrasound imaging acquired and interpreted by a treating clinician at the bedside of the patient, has emerged as an advance in clinical practice, allowing a dynamic study, which provides anatomical and/or physiological information to be integrated with clinical and laboratory data, for therapeutic decision-making and monitoring response, increasing the diagnostic accuracy of the traditional bedside assessment. Its bedside availability, safety and the possibility of repeating it as many times as necessary, make point of care ultrasound an emerging valuable and essential tool in Intensive Care Units. The concern that children are at a greater risk than adults to develop cancer after being exposed to radiation, has increase the interest of this discipline in the field of Pediatrics in recent years. Clinical lung ultrasound offers a valuable tool for the management of respiratory diseases. The technique and semiology are easy to learn. Lung ultrasound is based on interpretation of artifacts along with true images, depending on the normal aeration of the lung or its partial or complete loss. Since artifacts can be classified according to the air/fluid ratio, it is possible to create scores that inversely reflect the degree of lung aeration. In adults, different quantitative scores have been used to assess the degree of pulmonary aeration, which seems to be only useful in restrictive pulmonary disorders (acute respiratory distress syndrome, pneumonia, etc.). In recent years, some studies have been published on the usefulness of clinical lung ultrasound in acute bronchiolitis. The ultrasound pattern and its correlation with clinical severity, and a certain predictive capacity of ultrasound findings for the need and length of hospitalization, oxygen therapy, and respiratory support other than conventional oxygen have been described, but there are lack of studies including critical patients in PICU.
Therefore, it has not been proven yet that the improvement in the respiratory function experienced by children with moderate and severe acute bronchiolitis undergoing noninvasive respiratory support in PICU is due to an improvement in pulmonary aeration, and neither that patterns of greater loss of pulmonary aeration lead to greater clinical severity. For this reason, we carried out this study, to quantify pulmonary aeration by ultrasound, describe the ultrasound pattern on admission to the PICU of moderate and severe acute bronchiolitis, analyze the association between the ultrasound pulmonary aeration score with the clinical severity score and with the clinical progression, to assess the predictive capacity of the ultrasound lung aeration score with the need for mechanical ventilation, and to study the inter-observer agreement regarding the ultrasound findings. We conducted a prospective observational study in the PICU of Ramón y Cajal University Hospital, in three epidemic seasons of respiratory syncytial virus. The study included a total of 36 children <2 years old with clinical diagnosis of acute bronchiolitis, who needed respiratory support with high flow oxygen therapy or noninvasive ventilation, and in whom it was possible to perform two ultrasound examinations. A first clinical and ultrasound evaluation was performed on admission to the PICU, and a second evaluation 2-3 hours after starting noninvasive respiratory support. A quantitative pulmonary aeration score was obtained. We failed to demonstrate that the pulmonary aeration quantified by the ultrasound pulmonary aeration score had any correlation with the clinical severity, but we did find a correlation with the clinical progression in terms of length of PICU stay and length of hospital admission. Children younger than 3 months showed a greater loss of pulmonary aeration, showing a greater component of restrictive affectation. Respiratory syncytial virus infection, in single infection or in coinfection with other respiratory viruses did not determine different pulmonary aeration patterns. The ultrasound findings of acute bronchiolitis are multiple but non-specific, so clinical lung ultrasound cannot be used as an independent test for diagnosis, and should be considered as an extension of clinical evaluation. Inter-observer agreement was good, better for extreme patterns than for intermediate aeration loss patterns.
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