Foreign body aspiration — inhalation of an object into the larynx, trachea or lungs — is a common and potentially life-threatening condition for children. Diagnosis of foreign body aspiration can be challenging as symptoms can mimic many other childhood conditions.
As aspiration cases at Monroe Carell Jr. Children’s Hospital at Vanderbilt grew, a team of physicians sought to ensure that the most appropriate imaging tools were being used in the evaluation and diagnostic process for suspected aspirations.
What started as a quality improvement project years ago turned into a research immersion assignment for a recent Vanderbilt University School of Medicine graduate, Penny Li, MD. Physicians at Monroe Carell had noticed fewer negative bronchoscopies, a minimally invasive procedure to examine the airways and lungs, in children with suspected aspirations who had a CT scan compared to those who were also evaluated with a multiview chest X-ray.
“We wanted to see if that observation bore out in the data,” said Li, who will begin a residency in surgery at Vanderbilt Health on July 1. “Chest X-ray has been the standard imaging modality for decades, but it has obvious limitations, and its sensitivity is highly variable depending on the expertise of the person reading the study.
“We were also mindful of the heightened concern regarding radiation exposure in the pediatric population when evaluating imaging options.”
The team performed a single-center, retrospective chart review of pediatric patients who presented to the emergency department at Monroe Carell with concern for foreign body aspirations. The researchers examined the sensitivity and specificity of the two imaging methods (X-ray and CT) while factoring in cost and radiation dose to provide a complete picture.
They evaluated 330 patient charts over a six-year period and published the findings in the June issue of The Journal of Pediatrics.
“Reduced-dose CT was clearly superior to the chest X-ray for detection,” said Li, first author of the study. “Our findings support the routine use of low-dose CT for diagnosis of foreign body aspiration. We also found that this diagnostic tool can be used without delivering a clinically significant increase in radiation exposure or hospital expenditure.
“We want to emphasize that lowering the radiation dose on the CT does not compromise diagnostic quality when it is obtained for the evaluation of suspected foreign body aspiration,” she said. “All hospitals have the ability to achieve lower CT doses as all modern CT scanners have radiation dose-modulation capabilities. Techniques for dose reduction are commonplace in practice.”
Li said that aspirations are often unwitnessed, and a negative chest X-ray is not always conclusive. For example, if a chest X-ray is negative for a child brought in for suspected aspiration of a toy with plastic and metal parts, there is still uncertainty.
“Is the imaging negative because there is truly nothing in the airway or because the child aspirated a plastic part and not metal?” asked Li. “CT allows physicians to more confidently differentiate between the two possibilities. And from a surgical standpoint, CT provides much more detailed information than a chest X-ray about where the object is and what tools might be needed to retrieve it.”
Traditional, standard-dose CT requires sedation, while many reduced-dose options do not. Li said that information further supports the study findings that will hopefully lead to more routine use of reduced-dose CT scans as a first-line imaging tool.
“In conclusion, reduced-dose CT delivers highly sensitive and specific diagnostics for detection of FBA (foreign body aspiration) above multiview radiographs and without a clinically significant increase in radiation exposure,” the authors stated in the paper. “Integration of this technology into clinical protocols can be a powerful tool in institutional quality improvement, as CT can help to limit the number of missed diagnoses, decrease the negative bronchoscopy rate, and improve hospital resource utilization.”
Monroe Carell is a large referral center for aspiration evaluations and has begun working more rigorously with outside hospitals to streamline the workups and management of patients. Li hopes that the study will serve as a catalyst for institutions to revisit their own practices with respect to pediatric foreign body aspirations.
