Evaluation of lung ultrasonography in the diagnosis of childhood pneumonia at a tertiary hospital in Lagos, Nigeria

Abstract

Background: Pneumonia, a life-threatening lung disease of mankind and a major contributor to childhood morbidity and mortality in developing countries including Nigeria, is responsible for a quarter of all deaths in children under the age of five. Its more damaging effects in children is attributed to the status of their less matured lungs. The response to early diagnosis and appropriate treatment, has been a great consolation in the management of childhood pneumonia. Its diagnosis is usually based on clinical symptoms, signs and findings on chest radiographs. Advocacy on careful and judicious use of Conventional Radiography, an imaging modality that requires hazardous ionizing radiation for image acquisition, has been on the increase, propounding its avoidance in the growing child. This, coupled with the fact that a clear chest radiograph in pneumonia does not imply the absence of pneumonia, has necessitated the search for a more sensitive and less hazardous diagnostic imaging modality for diagnosis of pneumonia in children. Ultrasonography, a relatively new imaging modality which utilizes ultrasound for image acquisition and which when used in prescribed specifications for imaging has till date, recorded no deleterious effects, is safe for diagnostic and follow-up purposes, requirements in management of pneumonia, in this age group. Other advantages of ultrasonography are its affordability, availability, accessibility with images produced displaying features close to cut-sections', the equipment availability in variable sizes, some, small enough for use at the bedsides of very sick children, obviating the need to wheel them on their cots or beds, along hospital corridors towards Radiology Departments. The major limitation being that it is reliable only in well trained hands, which is not an absolute limitation as the Authors are willing to build capacity in the use of this invaluable imaging modality. Though Ultrasonography has been in clinical use since the early 1950s, it was not considered  appropriate for use in imaging the lungs until recently, the challenge being lung's air-filled nature, air being a very poor sound conductor. This same limitation however is being leveraged  upon for sonographic evaluation of lung diseases, since pneumonic changes involve replacement of air in the lung alveoli with inflammatory collections, thus distinguishing normal from abnormal lung appearances in ultrasonography. This novel and safe diagnostic imaging modality for assured use will need its reliability in diagnosis and follow-up of childhood pneumonia tested, hence the aim of this research, hoping the findings will add significantly to the knowledge of effective and efficient management of pneumonia in these frail children.
Aim and Objective: To determine the usefulness of lung ultrasonography (LUS) in diagnosing pneumonia in paediatric patients.
Methodology: This study was carried out on 150 children with clinical symptoms suggestive of pneumonia (such as fever, cough and respiratory distress), admitted via the Children's Emergency Unit of a tertiary hospital and from whose parents or guardians written Informed Consents had been obtained and codes given, to ensure confidentiality. Following clinical evaluation, diagnostic evaluations were independently carried out on lung ultrasound and chest radiography by the Researcher and Radiology Units on duty, findings from each imaging modality, blinded to each other.
Results: Of the 150 research participants whose chests were evaluated, chest radiography was able to detect pneumonia in 138 patients while lung ultrasonography detected pneumonia in 144 patients, the sensitivity and specificity of lung ultrasound findings being 91.67% and 33.33% respectively; the positive predictive value and negative predictive value are 97.06% and 14.29% respectively. The overall probability that a patient with pneumonia is correctly diagnosed by lung ultrasound is 89.33%.
Conclusion: Both imaging modalities (Chestradiography and Lung ultrasonography) and negative predictability, but higher diagnostic accuracy for the detection of pneumonia in children was observed with lung ultrasonography compared to chest radiography. Its safety, portability and bedside imaging possibility, makes LUS a robust diagnostic imaging modality in childhood pneumonia.

Keywords: Childhood pneumonia, lung ultrasound, chest radiography