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.