Analysis of clinical & radiological findings in children with acute wheeze

Objective: To analyze the indications for chest (CXR) radiography, radiological abnormalities and the clinical predictors for pneumonia in children who present with acute wheeze to the pediatric emergency department. Methods: This prospective study was conducted in the emergency department of a tertiary care pediatric referral hospital between July and December 2012. Children between 6 months to 18 years of age presenting with acute wheeze were included in the study. Results: Of a total of 126 children included in the study, the most common indication for CXR was temperature > 1000F at presentation (65%). The most common radiological abnormality was prominent bronchovascular markings in 67%. Ten children (8.7%) had radiological evidence of pneumonia, seven of them were <5years of age. Presence of fever during triage (p=0.006), hypoxia (p=0.01) and localised chest findings on auscultation (p=0.001) were statistically significant clinical predictors for pneumonia. Conclusion: The incidence of radiographically confirmed pneumonia among children with wheezing is uncommon. Definite clinical criteria should be defined to avoid unwarranted chest radiography in children with acute wheeze.


Introduction
Wheeze is a common paediatric emergency. Children with viral respiratory infection often present with fever and acute wheeze and a chest radiograph is often performed as it is difficult to identify pneumonia by clinical examination alone.
Identifying clinical parameters which are more likely to be associated with pneumonia in children who present with acute wheeze can possibly prevent unwarranted radiography.

Aim
The aim of our study was to analyse the radiological abnormalities, indications for chest radiography and the clinical predictors for pneumonia in children who present with an acute wheeze to the paediatric emergency department.

Materials and methods
This prospective study at the emergency department of a tertiary care paediatric referral hospital was conducted between July to December 2012. Children who presented with acute wheeze aged between 6 months to 18 years were included. Children with chronic lung disease, history of tracheostomy, complex congenital heart disease, underlying immunodeficiency and malignancy were excluded from study. The decision to obtain a chest x ray (CXR) was left to the discretion of pediatric post graduates, fellows in emergency medicine, registrars and paediatric consultants in the emergency room who was blinded to the ongoing study. Clinical parameters ( Table 1) such as fever, chest retractions, tachypnea, focal lung signs, oxygen saturation (SpO 2 ), age, the need for intensive care unit admission and findings on chest radiography were continually abstracted from medical records throughout the study period. Severity of wheeze was determined by the Pulmonary score index (PSI) [1]. PSI 0 -3 was mild, 4 -6 moderate and > 6 was considered as severe wheeze. The variables included in pulmonary score index are respiratory rate, wheeze and accessory muscle activity. All radiographs were reviewed by a qualified pediatric radiologist for the presence (as evidenced by consolidation) or absence of pneumonia.

Hypoxia
Localised chest finding square test was applied and p value of <0.05 was considered significant. Presence of fever (p=0.006), hypoxia (p=0.01) and localised chest findings (p=0.001) were statistically significant ( Table 2). PSI of more than 6 was not associated with pneu-monia.

Discussion
The criteria for ordering a chest x ray for children with acute wheeze are not well defined. Chest x rays are performed frequently in children who present with acute wheeze, as it is difficult to rule out pneumonia based on history and clinical examination alone. Pneumonia in children with acute wheeze is uncommon and imaging adds to the health care cost and exposure of children to ionizing radiation all of which can be avoided. Analysis of CXR taken for children with acute exacerbation of wheeze in the emergency department suggests that in most instances it does not alter the diagnosis or management. We found a low rate (8.7%) of radiographic pneumonia in our study population which is comparable to 4.9% in a study from Boston [2]. The prevalence of pneumonia in previous investigations varied widely, ranging from 8.6% to 35% [3][4][5].
In our study all children (100%) who had radiological evidence for pneumonia had triage temperature ≥ 101 0 F (p=0.006). A study from Pakistan also concludes that temperature of > 100 0 F was highly specific for poor response to bronchodilator and susequent deterioration. The overall positive predictive value was best for temperature of > 100 0 F [6]. We also observed in our study that in addition to temperature, hypoxia (p=0.01) and localised chest findings (p=0.001) were also statistically significant variables associated with pneumonia. The difference in Pulmonary score index in children without radiological pneumonia was not stastically significant as PSI mainly includes respiratory rate, wheeze and work of breathing. This observation is similar to a prospective study which reported that, among infants < 18 months of age, grunting on examination and oxygen saturation of < 93% were predictors of radiographic pneumonia, whereas fever and tachypnea were not associated with pneumonia risk [7]. In a study from Brazil, absence of pulmonary infiltrates was associated with the complaint of difficulty in breathing (P=0.04) and wheezing (P=0.001) [8]. It is also difficult to distinguish a viral process from bacterial pneumonia on chest radiographs, and radiographic pneumonia does not necessarily indicate a bacterial infection leading to overuse of antibiotics.

Conclusion
Majority of children with acute wheeze are subjected to chest radiography as they are febrile, though the occurrence of radiographic pneumonia is as low as (8.7%). Triage temperature of ≥ 101 0 F, hypoxia and localized chest findings were predictors of pneumonia in children with acute wheeze. Definite criteria have to be defined through larger studies to avoid unnecessary chest radiography.