Spectrum of Chest Radiographic Findings of Influenza A (H1N1) 2009 Virus Infection in Hospitalized Pediatric Patients in Siriraj Hospital

Objective: To evaluate chest radiographic findings of hospitalized pediatric patients with laboratory-confirmed influenza A (H1N1) 2009 virus infection in Siriraj Hospital, during June to August 2009. Methods: A total of 43 hospitalized pediatric patients with pandemic influenza A (H1N1) 2009 virus infection between June and August 2009 were included. Initial and follow up chest radiographs were retrospectively reviewed by two pediatric radiologists. Radiographic abnormalities were evaluated in pattern, distribution, and extension. Associated pleural abnormality, pneumothorax, pneumomediastinum and hilar lymphadenopathy were also reviewed. Results: Of 43 included cases, 22 were males and 21 were females, whose age ranged from 6-168 months (mean 75.58, median 74). Negative chest radiograph were found in 3 of 43 cases (6.98%). Most common radiographic abnormalities were peribronchial opacification (93.02%), patchy opacification (79.07%) and confluent opacification (13.95%). These lesions tended to be multifocal (73.42%), bilateral (74.83%) and centrally located (43.36%). Most of the cases improved clinically after medical treatment although, one of our cases died from superimposed ARDS. Most of the cases had clinical improvement after medical treatment with an average length of stay 10.8 days, although, one of them died from acute respiratory distress syndrome (ARDS). Conclusion: Most of hospitalized pediatric patients with H1N1 influenza virus infection had abnormal chest radiographs. The most common pattern was peribronchial opacification followed by patchy opacification and confluent opacification which trended to be multifocal, bilateral and centrally located.