Introduction
Lung ultrasound (LUS) has been proposed as an alternative first-line imaging modality to diagnose community acquired pneumonia in children, with promising results. (1) There is evidence that LUS may have greater sensitivity, similar specificity and better inter-operator reliability in the diagnosis of pneumonia when compared with chest radiography (CXR). (2-4) Moreover, LUS is radiation free and is subject to fewer regulatory requirements, has lower cost and easier bedside availability than CXR.
LUS has also been shown to be more sensitive than chest x-ray in identifying sub-centimeter air bronchograms often not evident on CXR. (5)
Consolidations appear at LUS as hypoechoic areas. (6,7) The pleural line in the wall above the consolidation is less echogenic or even disappeared. At the rear, the presence of compact vertical artifacts is frequent expression of wall reinforcements typically produced by areas with fluid content. (8,9) Interstitial pneumonia is represented by B lines isolated or confluent until to configure a white lung pattern based on gravity.
The incidence of pneumonia in cancer patients varies from 17 to 24% and clinical response to specific treatment varies from 60 to 65% with an infection-related mortality of 38%. (10-12) Pneumonia accounts for as much as 50% of septic shock cases in cancer patients.
Febrile neutropenia is one of the most frequent complications in cancer patients and sometimes, if not promptly treated has an unfavourable prognosis with evolution towards serious clinical problems such as septic shock, acute organ dysfunction, disseminated intravascular coagulation and eventually death. The lungs are one of the most frequent sites of infection in oncological patients during neutropenia. (10-13)
Diagnostic exams such as CXR and CT are required in febrile cancer patient. However, CXR, especially during neutropenia, is not very specific. It is unable to make differential diagnosis between bacterial, viral or mycotic pneumonia, and for this reason, in the suspicion of a fungal etiology (Candida or Aspergillus) patients undergo chest CT scan,that has higher specificity. Moreover, CXR has low sensitivity if performed in the initial phase of infection, particularly if performed in single projection: on the first day of fever it is often negative. (14, 15) The literature has also already established the inconsistent role of CXR in the diagnosis of lung infection in the neutropenic patient probably due to the low number of neutrophils involved in the production of the inflammatory response. (13) Chest CT scan is complicated by organizational difficulties and greater exposure to ionizing radiation, especially in these patients already subjected to many radiological examinations. (16) For all these reasons we need new methods for a correct and quick diagnosis of pneumonia.
Despite the large literature in the pediatric field on the role of LUS in the diagnosis of pneumonia, to our knowledge there are no studies concerning its utilization in the diagnosis and follow-up of pulmonary infection in children with cancer.
In our Unit of Pediatric Hematology and Oncology we recently introduced the routinely use of bed-side LUS, as an aid to physical examination, in order to evaluate pulmonary involvement and subsequent clinical management in both febrile in- and out-patients. This technique has recently been included in the diagnostic management of our patients, to optimize diagnostic and therapeutic choices during the Covid-19 pandemic.
The goal of this study is to explore the use of LUS as a tool for the diagnosis of pneumonia in children with cancer, neutropenic and non neutropenic.
In detail the primary objective of our study is to evaluate the diagnostic accuracy of LUS in pediatric cancer patients. We want to evaluate if, during neutropenia, there is a reduction in sensitivity of the ultrasound, similar to the CRX, compared to the non-neutropenic patients or if it allows to obtain a faithful image, such as the chest CT scan. Furthermore, we want to evaluate whether the underlying disease, the therapies administered (chemotherapy and radiotherapy) and the state of neutropenia can be factors influencing the sensitivity and specificity of the ultrasound examination.
The secondary objectives of the study are to evaluate the role of LUS in the follow-up of patients with lung infection and the tolerability of LUS, taking into account child’s age and his psycho-physical health.